View Filing Data

^[1]

976,978

1,116,583

(358,962)

(461,399)

Net property and equipment

618,016

655,184

Construction in progress

74,344

88,918

692,360

744,102

Right-of-Use Asset - Operating Leases

17,313

Investments, at Equity, and Advances to 50% or Less Owned Companies

124,680

121,773

Construction Reserve Funds

12,893

28,061

Other Assets

3,401

3,690

Assets Held for Sale

26,280

Total assets

1,009,193

1,102,938

Current Liabilities:

Current portion of operating lease liabilities

15,099

Current portion of long-term debt

17,802

16,812

Accounts payable and accrued expenses

25,691

18,089

Due to SEACOR Holdings

452

Accrued wages and benefits

1,832

4,122

Accrued interest

731

1,101

Accrued income taxes

1,918

Accrued capital, repair and maintenance expenditures

15,997

18,757

Deferred and Unearned revenues

5,327

1,460

Accrued insurance deductibles and premiums

3,564

3,403

Accrued professional fees

871

918

Derivatives

3,009

1,659

Other current liabilities

4,820

12,400

Liabilities associated with assets held for sale

2,526

Total current liabilities

94,817

83,617

Long-Term Operating Lease Liabilities

9,822

Long-Term Debt

380,251

387,854

Conversion Option Liability on Convertible Senior Notes

5,205

5,276

Deferred Income Taxes

33,905

44,685

Deferred Gains and Other Liabilities

6,269

26,571

Total liabilities

530,269

548,003

SEACOR Marine Holdings Inc. stockholders' equity:

Preferred stock, $.01 par value, 10,000,000 shares authorized; none issued nor outstanding

Common stock, $.01 par value, 60,000,000 shares authorized; 21,928,674 and 20,443,215 shares issued in 2019 and 2018, respectively

219

204

Additional paid-in capital

429,318

415,372

Retained earnings

27,076

126,834

Shares held in treasury of 47,185 and 4,007 in 2019 and 2018, respectively, at cost

(669)

(91)

Accumulated other comprehensive loss, net of tax

1,548

(16,788)

Total stockholders equity

457,492

525,531

Noncontrolling interests in subsidiaries

21,432

29,404

Total equity

478,924

554,935

Total liabilities and equity

$ 1,009,193

$ 1,102,938

[1]	Includes property and equipment acquired in business acquisitions at acquisition date fair value, and net of the impact of recognized impairment charges.

Consolidated Statements of Loss (Parenthetical) $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($)
Income Statement [Abstract]
Loss on disposal of business	$ 9,106

Discontinued Operations (Tables)

12 Months Ended

Dec. 31, 2019

Discontinued Operations And Disposal Groups [Abstract]

Schedule of Assets Held for Sale

Summarized selected operating result of the Company’s assets, previously classified as held for sale were as follows (in thousands):

	December 31,
	2018
Assets from Discontinued Operations:
Current assets	$	15,222
Net property and equipment		26,280
		41,502
Total current liabilities	$	2,526

	For the years ended December 31,
	2019			2018
Operating Revenues:
Time charter	$	41,214		$	49,902
Other revenue		45			140
		41,259			50,042
Costs and Expenses:
Operating		33,836			42,817
Direct Vessel Profit		7,423			7,225

General and Administrative Expenses		4,207			4,524
Lease Expense		60			71
Depreciation		3,504			3,405
(Loss) Gain on Asset Dispositions and Impairments, Net		91			2,521
Operating (Loss) Income		(257	)		1,746
Other Income (Expense)
Interest income		11			12
Interest expense		(210	)		(465	)
Foreign currency translation loss		(75	)		(53	)
		(274	)		(506	)
Operating (Loss) Income Before Equity Earnings of 50% or Less Owned Companies, Net of Tax		(531	)		1,240
Income Tax Expense		(2	)		7
Operating (Loss) Income Before Equity Earnings of 50% or Less Owned Companies		(529	)		1,233
Equity in Earnings (Losses) of 50% or Less Owned Companies, Net of Tax		168			137
Net (Loss) Income from Discontinued Operations	$	(361	)	$	1,370

- Definition

Tabular disclosure of information related to a disposal group. Includes, but is not limited to, a discontinued operation, disposal classified as held-for-sale or disposed of by means other than sale or disposal of an individually significant component.

+ References

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+ Details

Investments, at Equity, and Advances to 50% or Less Owned Companies - Additional Information (Details)									3 Months Ended		12 Months Ended
	Dec. 18, 2019 USD ($)	May 31, 2019 USD ($) Vessel	Dec. 28, 2018 USD ($)	Dec. 20, 2018 USD ($)	Sep. 28, 2018 USD ($) Vessel	Sep. 13, 2018 USD ($)	Jan. 17, 2018 USD ($) Vessel	Apr. 28, 2017 USD ($) Catamaran	Sep. 30, 2018 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2019 USD ($) Vessel Equipment	Dec. 31, 2018 USD ($) Vessel Liftboat	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Feb. 08, 2018
Schedule Of Investments [Line Items]
Consolidated retained earnings											$ 16,100,000	$ 28,500,000
Payments to acquire property, plant, and equipment, total											55,456,000	51,578,000	$ 68,983,000
Contributed capital				$ 10,000,000
Equity method investment, ownership percentage				49.00%
Sale of subsidiary to joint venture												8,017,000
Equity method investment, other than temporary impairment											0	1,200,000	8,800,000
Income (loss) from equity method investments											(14,304,000)	(3,552,000)	3,851,000
Equity method investments											105,221,000	121,773,000
Principal payments on notes due from equity investees											22,000	116,000
Asset impairment charges, total											$ 12,000,000	14,600,000	27,500,000
Maximum
Schedule Of Investments [Line Items]
Equity method investment, ownership percentage											50.00%
Minimum
Schedule Of Investments [Line Items]
Equity method investment, ownership percentage											20.00%
MEXICO
Schedule Of Investments [Line Items]
Number of vessels owned \| Vessel											3
Mexmar Offshore International
Schedule Of Investments [Line Items]
Equity method investment, ownership percentage				49.00%
Noncontrolling interest, ownership percentage by noncontrolling owners				51.00%
Number of vessels owned \| Vessel											13
Mexmar Offshore International \| BRAZIL
Schedule Of Investments [Line Items]
Number of vessels owned \| Vessel											10
Mexmar Offshore International \| MEXICO
Schedule Of Investments [Line Items]
Number of vessels owned \| Vessel											2
Offshore Vessel Holdings
Schedule Of Investments [Line Items]
Contributed capital											$ 10,000,000
Noncontrolling interest, ownership percentage by noncontrolling owners			51.00%
Noncontrolling Interest, ownership percentage by parent			49.00%
Payments to acquire interest in joint venture			$ 4,900,000
Financing agreement											$ 2,400,000
Offshore Support Vessels, Supply
Schedule Of Investments [Line Items]
Number of vessels owned \| Vessel											1
Offshore Support Vessels, Supply \| Offshore Vessel Holdings
Schedule Of Investments [Line Items]
Number of equipment operated \| Equipment											3
Jack up Drillings [Member] \| Offshore Vessel Holdings
Schedule Of Investments [Line Items]
Number of equipment operated \| Equipment											2
F S V Offshore Support Vessels \| Offshore Vessel Holdings
Schedule Of Investments [Line Items]
Number of equipment operated \| Equipment											1
MexMar
Schedule Of Investments [Line Items]
Capital distributions from equity investees						$ 9,800,000					$ 0	9,800,000
Revenue from related parties											$ 300,000	300,000	300,000
Equity method investment, ownership percentage											49.00%
Number of vessels owned \| Vessel											16
Equity method investments											$ 54,249,000	53,840,000
MexMar \| Offshore Support Vessels
Schedule Of Investments [Line Items]
Number of equipment operated \| Vessel											16
SeaCosco Offshore LLC
Schedule Of Investments [Line Items]
Number of equipment operated \| Vessel							8
Payments to acquire property, plant, and equipment, total							$ 163,300,000
Contributed capital											$ 2,000,000	29,600,000
Equity method investment, ownership percentage											50.00%
Number of vessels owned \| Vessel											1
Equity method investments											$ 23,926,000	$ 28,002,000
SeaCosco Offshore LLC \| MOU
Schedule Of Investments [Line Items]
Agreement standstill date		Aug. 31, 2019
Loans receivable, interest rate		15.00%
Shareholder loans in respect of working capital		$ 13,000,000
Interest income recognized on shareholder loans in respect of working capital		600,000
Advanced contributed capital		$ 2,100,000
SeaCosco Offshore LLC \| SEACOR Offshore Asia
Schedule Of Investments [Line Items]
Equity method investment, ownership percentage							50.00%
SeaCosco Offshore LLC \| CSFT and CSIHK
Schedule Of Investments [Line Items]
Equity method investment, ownership percentage							50.00%
SeaCosco Offshore LLC \| CSFT and CSIHK \| MOU
Schedule Of Investments [Line Items]
Equity method investment, ownership percentage		50.00%
SeaCosco Offshore LLC \| Platform Supply Vessels
Schedule Of Investments [Line Items]
Number of vessels delivered to the company \| Vessel											5	2
SeaCosco Offshore LLC \| Platform Supply Vessels \| MOU
Schedule Of Investments [Line Items]
Number of vessels acquired \| Vessel		2
OSV Partners
Schedule Of Investments [Line Items]
Revenue from related parties											$ 0	$ 600,000	600,000
Contributed capital					$ 5,000,000								2,300,000
Equity method investment, ownership percentage											30.40%
Investment in affiliates, amount of preferred equity offering participated					5,000,000
Payments to acquire interest in subsidiaries and affiliates, total	$ 1,100,000				1,100,000
Commitment to invest additional funds if call by general partner					1,100,000
Payments to acquire loans receivable					$ 2,100,000
Equity method investments											$ 10,669,000	11,087,000
OSV Partners \| General Partner
Schedule Of Investments [Line Items]
Contributed capital													6,000,000
Equity method investment, ownership percentage											38.60%
OSV Partners \| Offshore Support Vessels
Schedule Of Investments [Line Items]
Number of equipment operated \| Vessel					5
SEACOR Marlin LLC
Schedule Of Investments [Line Items]
Equity method investment, ownership percentage											49.00%
Equity method investment, ownership, percent sold						51.00%
Sale of subsidiary to joint venture						$ 8,000,000
Gain (loss) on disposition of business						$ 400,000
Equity method investments											$ 7,929,000	7,579,000
Dynamic Offshore
Schedule Of Investments [Line Items]
Equity method investment, ownership percentage											19.00%
Equity method investment, other than temporary impairment													8,300,000
Income (loss) from equity method investments											$ (2,300,000)	(2,000,000)
Equity method investments											$ 0	$ 2,263,000
Nautical Power
Schedule Of Investments [Line Items]
Equity method investment, ownership percentage											50.00%
Sale of subsidiary to joint venture									$ 6,400,000
Falcon Global
Schedule Of Investments [Line Items]
Contributed capital										$ 400,000
Equity method investment, ownership percentage															100.00%
Payments for advance to affiliate										$ 2,000,000
Business acquisition, percentage of voting interests acquired										100.00%
Falcon Global \| Liftboats
Schedule Of Investments [Line Items]
Number of equipment operated \| Liftboat												2
Sea-Cat Crewzer II
Schedule Of Investments [Line Items]
Number of equipment operated \| Catamaran								2
Equity method investment, ownership percentage								50.00%
Business acquisition, percentage of voting interests acquired								100.00%
Payments to acquire businesses, gross								$ 11,300,000
Sea-Cat Crewzer
Schedule Of Investments [Line Items]
Number of equipment operated \| Catamaran								2
Equity method investment, ownership percentage								50.00%
Business acquisition, percentage of voting interests acquired								100.00%
Payments to acquire businesses, gross								$ 4,400,000
Other Offshore Marine Services Joint Ventures
Schedule Of Investments [Line Items]
Number of equipment operated \| Vessel											5
Capital distributions from equity investees											$ 2,100,000		2,600,000
Revenue from related parties													300,000	$ 700,000
Contributed capital													800,000
Equity method investment, other than temporary impairment												$ 1,200,000	500,000
Equity method investments											4,396,000	$ 9,202,000
Return of capital equity method investment											500,000
Principal payments on notes due from equity investees													$ 200,000
Other Offshore Marine Services Joint Ventures \| Maximum
Schedule Of Investments [Line Items]
Revenue from related parties											$ 100,000
Equity method investment, ownership percentage											50.00%
Other Offshore Marine Services Joint Ventures \| Minimum
Schedule Of Investments [Line Items]
Equity method investment, ownership percentage											20.00%

Consolidated Statements of Changes In Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Treasury Stock [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Loss [Member]	Non-Controlling Interests In Subsidiaries [Member]
Balance at Dec. 31, 2016						$ (11,337)
Net Loss	$ (38,540)
Other comprehensive loss	(881)
Balance at Dec. 31, 2017	523,166	$ 177	$ 303,996		$ 216,511	(12,493)	$ 14,975
Balance (in shares) at Dec. 31, 2017		17,675,356
Impact of adoption of accounting principle at Dec. 31, 2017	(12,069)				(12,069)
Balance at Dec. 31, 2017	511,097	$ 177	303,996		204,442	(12,493)	14,975
Issuance of Common Stock	42,996	$ 23	42,973
Issuance of Common Stock (in shares)		2,291,084
Issuance of Warrants	62,809		62,809
Amortization of employee share awards	3,494		3,494
Exercise of options	$ 833	$ 1	832
Exercise of options (in shares)	66,625	66,625
Exercise of Warrants		$ 3		$ (3)
Exercise of Warrants (in shares)		289,442		108
Restricted stock vesting	$ (88)			$ (88)
Restricted stock vesting (in shares)		116,701		3,899
Director share awards	893		893
Acquisition of consolidated joint venture	(12,037)						(12,037)
Issuance of noncontrolling interests	31,385		375				31,010
Net Loss	(82,052)				(77,608)		(4,444)
Other comprehensive loss	(4,395)					(4,295)	(100)
Balance at Dec. 31, 2018	$ 554,935	$ 204	415,372	$ (91)	126,834	(16,788)	29,404
Balance (in shares) at Dec. 31, 2018	20,443,215	20,439,208		4,007
Impact of adoption of accounting principle at Dec. 31, 2018	$ 10,416				10,416
Balance at Dec. 31, 2018	565,351	$ 204	415,372	$ (91)	137,250	(16,788)	29,404
Issuance of Common Stock	6,596	$ 7	6,589
Issuance of Common Stock (in shares)		653,872
Restricted stock grants	2	$ 2
Restricted stock grants (in shares)		245,400
Cancellation of restricted stock grants (in shares)		(2,200)
Amortization of employee share awards	5,046		5,046
Exercise of options	$ 1,421	$ 1	1,420
Exercise of options (in shares)	113,750	113,750
Exercise of Warrants	$ 3	$ 4		(1)
Exercise of Warrants (in shares)		444,391
Restricted stock vesting	(579)		(2)	$ (577)
Restricted stock vesting (in shares)		(43,129)		43,129
Director share awards	894	$ 1	893
Director share awards (in shares)		30,197		49
Acquisition of consolidated joint venture	(2,114)						(2,114)
Sale of Standby Safety Fleet	(17,399)				(17,399)
Dissolution of Entity	62				62
Net Loss	(98,695)				(92,837)		(5,858)
Other comprehensive loss	18,336					18,336
Balance at Dec. 31, 2019	$ 478,924	$ 219	$ 429,318	$ (669)	$ 27,076	$ 1,548	$ 21,432
Balance (in shares) at Dec. 31, 2019	21,928,674	21,881,489		47,185

Business Acquisitions - Additional Information (Details) - USD ($) $ in Millions	Feb. 08, 2018	Dec. 31, 2018
Falcon Global Holdings
Noncontrolling Interest, ownership percentage by parent	72.00%	72.00%
Falcon Global Holdings
Joint venture, total capital	$ 112.5
Joint venture, contribution from previous joint venture	43.3
Joint venture, contribution from noncontrolling interest	$ 18.8

Leases - Summary of Components of Leases Expense (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($)
Leases [Abstract]
Operating lease expense	$ 13,639
Short-term lease expense (lease duration of twelve months or less at lease commencement)	2,519
Total Lease expense	$ 16,158

Related Party Transactions (Tables)

12 Months Ended

Dec. 31, 2019

Schedule of Related Party Transactions

These costs and expenses are included in both operating and administrative and general expenses in the accompanying consolidated statements of loss and are summarized as follows for the year ended December 31, 2017 (in thousands):

	2017
Participation in SEACOR Holdings employee benefit plans	$	899
Participation in SEACOR Holdings share award plans		8,383
Shared services allocation for administrative support		1,932
	$	11,214

Construction Reserve Funds

12 Months Ended

Dec. 31, 2019

Restricted Cash And Investments [Abstract]

Construction Reserve Funds

6.	CONSTRUCTION RESERVE FUNDS

The Company has established, pursuant to Section 511 of the Merchant Marine Act, 1936, as amended, construction reserve fund accounts subject to agreements with the Maritime Administration. In accordance with this statute, the Company is permitted to deposit proceeds from the sale of certain vessels into the construction reserve fund accounts and defer the taxable gains realized from the sale of those vessels. Qualified withdrawals from the construction reserve fund accounts are only permitted for the purpose of acquiring qualified U.S.-flag vessels as defined in the statute and approved by the Maritime Administration. To the extent that sales proceeds are reinvested in replacement vessels, the carryover depreciable tax basis of the vessels originally sold is attributed to the U.S.-flag vessels acquired using such qualified withdrawals. The construction reserve funds must be committed for expenditure within three years of the date of sale of the equipment, subject to two one-year extensions that can be granted at the discretion of the Maritime Administration or be released for the Company’s general use as nonqualified withdrawals. For nonqualified withdrawals, the Company is obligated to pay taxes on the previously deferred gains at the prevailing statutory tax rate plus penalties and interest thereon for the period such taxes were deferred.

As of December 31, 2019, 2018 and 2017, the Company’s construction reserve funds are classified as non-current assets in the accompanying consolidated balance sheets as the Company has the intent and ability to use the funds to acquire equipment. Construction reserve fund transactions for the years ended December 31 were as follows (in thousands):

	2019			2018			2017
Withdrawals	$	(15,168	)	$	(17,300	)	$	(39,163	)
Deposits		—			—			6,315
	$	(15,168	)	$	(17,300	)	$	(32,848	)

Transformation, Facility Restructuring and Severance Charges - Schedule of Severance and Other Restructuring Charges (Details) - Transformation Plan $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($)
Restructuring Cost And Reserve [Line Items]
Restructuring liability	$ 249
Severance Liability
Restructuring Cost And Reserve [Line Items]
Restructuring liability	249
UNITED STATES
Restructuring Cost And Reserve [Line Items]
Restructuring liability	216
UNITED STATES \| Severance Liability
Restructuring Cost And Reserve [Line Items]
Restructuring liability	216
Europe
Restructuring Cost And Reserve [Line Items]
Restructuring liability	33
Europe \| Severance Liability
Restructuring Cost And Reserve [Line Items]
Restructuring liability	$ 33

Income Taxes - Schedule of Income before Income Tax (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Taxes [Line Items]
Income before income tax expense (benefit) and equity in earnings of 50% or less owned companies	$ (82,836)	$ (93,224)	$ (117,790)
United States
Income Taxes [Line Items]
Income before income tax expense (benefit) and equity in earnings of 50% or less owned companies	(71,833)	(72,540)	(90,696)
Foreign
Income Taxes [Line Items]
Income before income tax expense (benefit) and equity in earnings of 50% or less owned companies	(22,025)	(29,466)	(45,879)
Eliminations
Income Taxes [Line Items]
Income before income tax expense (benefit) and equity in earnings of 50% or less owned companies	$ 11,022	$ 8,782	$ 18,785

Derivative Instruments and Hedging Strategies - Additional Information (Details) $ in Thousands, € in Millions	12 Months Ended
	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2019 EUR (€)
Derivative [Line Items]
Other comprehensive income (loss), unrealized gain (loss) on derivatives arising during period, before tax	$ (1,901)	$ (1,939)	$ 214
Derivative, Fair Value, Net, Total	8,200
Interest Rate Swap
Derivative [Line Items]
Other comprehensive income (loss), unrealized gain (loss) on derivatives arising during period, before tax	$ (1,901)	(1,939)	214
Interest Rate Swap \| OSV Partners
Derivative [Line Items]
Derivative, number of instruments held, total	2			2
Derivative, notional amount	$ 22,800
Interest Rate Swap \| OSV Partners \| Minimum
Derivative [Line Items]
Derivative, fixed interest rate	1.89%			1.89%
Interest Rate Swap \| OSV Partners \| Maximum
Derivative [Line Items]
Derivative, fixed interest rate	2.27%			2.27%
Cash Flow Hedging
Derivative [Line Items]
Other comprehensive income (loss), unrealized gain (loss) on derivatives arising during period, before tax	$ (1,300)	$ 1,600	(200)
Cash Flow Hedging \| Interest Rate Swap \| Designated as Hedging Instrument \| Windcat Workboats Holdings Ltd
Derivative [Line Items]
Derivative, number of instruments held, total	2			2
Derivative, fixed interest rate	0.03%			0.03%
Derivative, notional amount	$ 16,800			€ 15.0
Cash Flow Hedging \| Interest Rate Swap \| Designated as Hedging Instrument \| SEACOR 88/888
Derivative [Line Items]
Derivative, fixed interest rate	3.175%			3.175%
Derivative, notional amount	$ 5,500
Cash Flow Hedging \| Interest Rate Swap \| Designated as Hedging Instrument \| MexMar
Derivative [Line Items]
Derivative, number of instruments held, total	5			5
Derivative, notional amount	$ 83,200
Cash Flow Hedging \| Interest Rate Swap \| Designated as Hedging Instrument \| MexMar \| Minimum
Derivative [Line Items]
Derivative, fixed interest rate	1.71%			1.71%
Cash Flow Hedging \| Interest Rate Swap \| Designated as Hedging Instrument \| MexMar \| Maximum
Derivative [Line Items]
Derivative, fixed interest rate	2.10%			2.10%
Cash Flow Hedging \| 3.32% Interest Rate Swap Agreement \| Designated as Hedging Instrument \| SEACOR Marine Foreign Holdings
Derivative [Line Items]
Derivative, fixed interest rate	3.32%			3.32%
Derivative, notional amount	$ 8,800
Cash Flow Hedging \| 3.195% Interest Rate Swap Agreement \| Designated as Hedging Instrument \| SEACOR Marine Foreign Holdings
Derivative [Line Items]
Derivative, fixed interest rate	3.195%			3.195%
Derivative, notional amount	$ 48,600
Construction in Progress \| Fair Value Hedging
Derivative [Line Items]
Change in unrealized gain (loss) on hedged item in fair value hedge			$ 100

Long Term Debt - Schedule of Long-term Debt Maturities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Debt Disclosure [Abstract]
2020	$ 17,802
2021	51,789
2022	26,007
2023	231,674
2024	90,800
Years subsequent to 2024	11,752
Long-term Debt, Gross	$ 429,823	$ 442,972

Major Customers and Segment Information - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
Revenue from contract with customer, including assessed tax	$ 49,070	$ 54,700	$ 52,812	$ 44,910	$ 58,897	$ 58,169	$ 47,871	$ 38,630	$ 201,492	$ 203,567	$ 123,421
Income (loss) from equity method investments									(14,304)	(3,552)	3,851
Customer Concentration Risk \| Sales Revenue, Net \| Seacor Marine Arabia LLC
Segment Reporting Information [Line Items]
Revenue from contract with customer, including assessed tax									$ 30,800	$ 21,400	$ 16,000
Concentration risk, percentage									15.00%	10.00%	13.00%
Customer Concentration Risk \| Sales Revenue, Net \| Ten Largest Customers
Segment Reporting Information [Line Items]
Concentration risk, percentage									44.00%	49.00%	58.00%
Geographic Concentration Risk \| Sales Revenue, Net \| Non-US
Segment Reporting Information [Line Items]
Income (loss) from equity method investments									$ (12,800)	$ (3,000)	$ 2,000
Geographic Concentration Risk \| Sales Revenue, Net \| Zamil Offshore
Segment Reporting Information [Line Items]
Revenue from contract with customer, including assessed tax									$ 20,300	$ 12,200	$ 4,500
Concentration risk, percentage									10.00%	6.00%	4.00%
Geographic Concentration Risk \| Sales Revenue, Net \| Saudi Aramco
Segment Reporting Information [Line Items]
Revenue from contract with customer, including assessed tax									$ 10,500	$ 9,200	$ 11,200
Concentration risk, percentage									5.00%	4.00%	9.00%
Geographic Concentration Risk \| Stockholders' Equity \| Non-US
Segment Reporting Information [Line Items]
Concentration risk, percentage									78.00%	36.00%	82.00%

Subsequent Events - Additional Information (Details) - USD ($) $ in Thousands		12 Months Ended
	Feb. 07, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Feb. 08, 2018
Repayments of long-term debt, total		$ 23,974	$ 49,405	$ 11,926
Omnibus Amendment \| Term and Revolving Loan Facility
Debt agreement maximum borrowing capacity					$ 131,100
Omnibus Amendment \| Subsequent Event
Repayment terms	the extension from March 2020 to March 2021 of the commencement of monthly repayment of the term loan, with payments being the lesser of (a) $0.8 million per month and (b) the amount outstanding under the term loan
Repayments of long-term debt, total	$ 800
Extension term of Guaranty	1 year
Outstanding principal amount	$ 117,300
Omnibus Amendment \| Subsequent Event \| Term Loan Facility
Outstanding principal amount	102,300
Omnibus Amendment \| Subsequent Event \| Revolving Credit Facility
Outstanding principal amount	$ 15,000

Quarterly Financial Information (Unaudited) (Tables)

12 Months Ended

Dec. 31, 2019

Quarterly Financial Information Disclosure [Abstract]

Selected Financial Information for Interim Quarterly Periods

	Three Months Ended
	Dec. 31,			Sept. 30,			June 30,			March 31,
2019
Operating Revenues	$	49,070		$	54,700		$	52,812		$	44,910
Operating Loss		(10,497	)		(3,355	)		(17,640	)		(21,034	)
Net (Loss) Income:
Continuing Operations		(19,176	)		(10,341	)		(31,438	)		(28,273	)
Discontinued Operations		(2,742	)		(7,899	)		1,174			—
	$	(21,918	)	$	(18,240	)	$	(30,264	)	$	(28,273	)
Net Loss attributable to SEACOR Marine Holdings Inc:	$	(20,455	)	$	(18,444	)	$	(28,389	)	$	(25,549	)
Basic and Diluted Loss Per Common Share of SEACOR Marine Holdings Inc.
Continuing Operations	$	(0.74	)	$	(0.49	)	$	(1.31	)	$	(1.16	)
Discontinued Operations	$	(0.12	)	$	(0.29	)	$	0.10		$	0.05
	$	(0.86	)	$	(0.78	)	$	(1.21	)	$	(1.11	)
2018
Operating Revenues	$	58,897		$	58,169		$	47,871		$	38,630
Operating Loss		(11,253	)		(12,207	)		(20,842	)		(24,206	)
Net (Loss) Income:
Continuing Operations		(7,780	)		(17,706	)		(26,505	)		(31,430	)
Discontinued Operations		(189	)		1,940			(124	)		(258	)
	$	(7,969	)	$	(15,766	)	$	(26,629	)	$	(31,688	)
Net Loss attributable to SEACOR Marine Holdings Inc:	$	(7,794	)	$	(15,957	)	$	(25,024	)	$	(28,833	)
Basic and Diluted Loss Per Common Share of SEACOR Marine Holdings Inc.
Continuing Operations	$	(0.39	)	$	(0.85	)	$	(1.18	)	$	(1.63	)
Discontinued Operations	$	0.04		$	0.14		$	(0.01	)	$	(0.01	)
	$	(0.35	)	$	(0.71	)	$	(1.19	)	$	(1.64	)

Equipment Acquisitions and Dispositions - Additional Information (Details)	12 Months Ended
	Dec. 31, 2019 USD ($) Vessel	Dec. 31, 2019 GBP (£) Vessel	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Property Plant And Equipment [Line Items]
Capital expenditures and payments on equipment	$ 55,500,000		$ 51,600,000	$ 69,000,000
Gain (loss) on disposition of property, plant and equipment			5,700,000	3,900,000
Proceeds from sale of business	56,183,000		20,140,000	10,701,000
Net book value	692,360,000		744,102,000
Proceeds from deposits			100,000
Proceeds from sale of property, plant, and equipment, including deposits			17,400,000	10,900,000
Proceeds from sale of property, plant, and equipment, excluding deposits for future vessel sales			17,300,000
Increase (Decrease) in contract with customer, liability			$ 4,400,000	$ 100,000
Vessel Under Construction
Property Plant And Equipment [Line Items]
Gain (loss) on disposition of property, plant and equipment	6,600,000
Proceeds from sale of business	$ 55,100,000
Number of equipment sold \| Vessel	1	1
Proceeds from property, plant, and equipment, including deposits and gain on sale	$ 59,400,000
Proceeds from deposits	$ 4,300,000
Anchor Handling Towing Supply
Property Plant And Equipment [Line Items]
Number of equipment sold \| Vessel	5	5
Specialty Vessel
Property Plant And Equipment [Line Items]
Number of equipment sold \| Vessel	1	1
Fast Support Vessels
Property Plant And Equipment [Line Items]
Number of equipment sold \| Vessel	7	7
Anchor Handling Towing Supply Vessel and Other Equipment
Property Plant And Equipment [Line Items]
Number of equipment sold \| Vessel	1	1
Liftboats
Property Plant And Equipment [Line Items]
Number of equipment sold \| Vessel	3	3
Crew Transfer Vessels
Property Plant And Equipment [Line Items]
Number of equipment sold \| Vessel	1	1
Platform Supply Vessels
Property Plant And Equipment [Line Items]
Number of equipment sold \| Vessel	5	5
ERRV Fleet Business
Property Plant And Equipment [Line Items]
Gain (loss) on disposition of property, plant and equipment	$ (9,100,000)
Proceeds from sale of business	27,390,000
Net book value	23,400,000
Additional consideration	$ 5,200,000	£ 4,000,000
ERRV Fleet Business \| Vessels
Property Plant And Equipment [Line Items]
Number of equipment sold \| Vessel	18	18

Savings and Multi-employer Pension Plans

12 Months Ended

Dec. 31, 2019

Compensation And Retirement Disclosure [Abstract]

Savings and Multi-employer Pension Plans

15.	SAVINGS AND MULTI-EMPLOYER PENSION PLANS

SEACOR Marine Savings Plan. On January 1, 2016, the Company’s eligible U.S. based employees were transferred from the SEACOR Holdings sponsored defined contribution plan to the “SEACOR Marine 401(k) Plan,” a new Company sponsored defined contribution plan (the “Savings Plan”). Effective upon the June 1, 2017 Spin-off, the Company discontinued its contribution to the Savings Plan up until January 1, 2019, at which time the Company’s contribution will be limited to 1.0% of an employee’s wages. The Savings Plan costs for the year ended December 31, 2019 was $0.3 million.

MNOPF and MNRPF. Certain of the Company’s subsidiaries are participating employers in two industry-wide, multi-employer, defined benefit pension funds in the United Kingdom: the U.K Merchant Navy Officers Pension Fund (“MNOPF”) and the U.K. Merchant Navy Ratings Pension Fund (“MNRPF”). The Company’s participation in the MNOPF began with the acquisition of the Stirling group of companies (the “Stirling Group”) in 2001 and relates to certain officers employed between 1978 and 2002 by the Stirling Group and/or its predecessors. The Company’s participation in the MNRPF also began with the acquisition of the Stirling Group in 2001 and relates to ratings employed by the Stirling Group and/or its predecessors through today. Both of these plans are in deficit positions and, depending upon the results of future actuarial valuations, it is possible that the plans could experience funding deficits that will require the Company to recognize payroll related operating expenses in the periods invoices are received.

Under the direction of a court order, any funding deficit of the MNOPF is to be remedied through funding contributions from all participating current and former employers. Prior to 2015, the Company was invoiced and expensed $19.4 million for its allocated share of the then cumulative funding deficits, including portions deemed uncollectible due to the non-existence or liquidation of certain former employers. The invoiced amounts have been re-paid in full, other than with respect to $2.6 million invoiced in 2013, for which the Company has a repayment plan with the trustees of the MNOPF to repay such invoice in full by December 31, 2023. As of December 31, 2019, the remaining current and long-term liability due to the MNOPF were $0.3 million and $0.7 million, respectively.

On November 7, 2018, the Company received notice from MNOPF that a deficit of £9.0 million existed but noted that the trustee did not propose to collect any additional funds in respect of such deficit. Depending on the results of future valuations, it is possible that the MNOPF will experience further funding deficits requiring the Company to recognize payroll related expenses in the periods the notice is received.

The cumulative funding deficits of the MNRPF were being recovered by additional annual contributions from current employers that were subject to adjustment following the results of future tri-annual actuarial valuations. In 2015, the Company was invoiced and expensed $6.9 million for its share of a funding deficit in the MNRPF. The Company had a repayment plan with the trustees of the MNRPF for the amount to be repaid in full by October 30, 2018 and the amounts were settled by that date. On July 20, 2018, the Company was notified of additional contributions due and recognized in the second quarter of 2018 payroll related expenses of $1.19 million (£0.9 million) for its allocated share of the cumulative funding deficit including portions deemed uncollectible due to the non-existence or liquidation of certain former employers. These additional contributions were invoiced in September 2018 and are payable in four annual installments beginning October 2018. As of December 31, 2019, all invoices related to the MNRPF have been settled in full. Depending upon the results of future actuarial valuations it is possible that the plan could experience further funding deficits that will require the Company to recognize payroll related operating expenses for those periods.

Other Plans. Certain employees participate in other defined contribution plans in various international regions including the United Kingdom and Singapore. During the years ended December 31, 2019, 2018 and 2017, the Company incurred costs of $0.3 million in 2019 and $0.2 million for 2018 and 2017, primarily from employer matching contributions.

Derivative Instruments and Hedging Strategies (Tables)

12 Months Ended

Dec. 31, 2019

Derivative Instruments And Hedging Activities Disclosure [Abstract]

Schedule of Fair Value of Derivative Assets and Liabilities

Derivative instruments are classified as either assets or liabilities based on their individual fair values. The fair values of the Company’s derivative instruments as of December 31 were as follows (in thousands):

		2019				2018
	Balance Sheet Classification	Derivative Asset		Derivative Liability		Derivative Asset		Derivative Liability
Derivatives designated as hedging instruments:
Interest rate swap agreements (cash flow hedges)	Current	$	—	$	3,009	$	—	$	1,659
			—		3,009		—		1,659
Derivatives not designated as hedging instruments:
Conversion option liability on Convertible Senior Notes	Long-Term		—		5,205		—		5,276
		$	—	$	8,214	$	—	$	6,935

Effect of Derivative Instruments on Other Comprehensive Income (Loss)

The following tables reflect amounts recorded in Other Comprehensive Income (“OCI”) and amounts reclassified from OCI to revenue and expense for the periods indicated:

	Gain (Loss) Recognized in OCI on Derivatives (Effective Portion)
Derivatives in Cash Flow Hedging Relationships	2019			2018			2017
Interest rate swap contracts	$	(1,901	)	$	(1,939	)	$	214
Joint venture interest rate swap contracts		(645	)		(76	)		389

	Gain (Loss) Reclassified from OCI into Income (Effective Portion)
Location of Gain	2019			2018			2017
Interest expense	$	552		$	31			118

Schedule of Gains (Losses) on Derivative Instruments not Designated as Hedging Instruments

The Company recognized gains (losses) on derivative instruments not designated as hedging instruments for the years ended December 31 as follows (in thousands):

	Derivative gains (losses), net
	2019		2018		2017
Conversion option liability on Convertible Senior Notes	$	71	$	1,556	$	20,422
Interest rate swap agreements		—		1,298		46
Forward currency exchange, option and future contracts		—		—		(212	)
	$	71	$	2,854	$	20,256

Transformation, Facility Restructuring and Severance Charges - Schedule of Cumulative Restructuring and Reorganization Cost Incurred to Date, Estimated Remaining and to be Incurred (Details) $ in Thousands	Dec. 31, 2019 USD ($)
Restructuring Cost And Reserve [Line Items]
Total restructuring and reorganization costs incurred	$ 3,718
Total restructuring and reorganization costs to be incurred	2,014
Total restructuring and reorganization costs incurred and to be incurred	5,732
One-time termination benefits
Restructuring Cost And Reserve [Line Items]
Total restructuring and reorganization costs incurred	3,379
Total restructuring and reorganization costs to be incurred	2,014
Total restructuring and reorganization costs incurred and to be incurred	5,393
Professional And Other
Restructuring Cost And Reserve [Line Items]
Total restructuring and reorganization costs incurred	339
Total restructuring and reorganization costs incurred and to be incurred	$ 339

Noncontrolling Interests in Subsidiaries

12 Months Ended

Dec. 31, 2019

Noncontrolling Interest [Abstract]

Noncontrolling Interests in Subsidiaries

14.	NONCONTROLLING INTERESTS IN SUBSIDIARIES

Noncontrolling interests in the Company’s consolidated subsidiaries as of December 31 were as follows (in thousands):

	Noncontrolling Interests				2019		2018
Falcon Global Holdings		28.0	%		$	21,119	$	26,989
Windcat Workboats		—		⁽¹⁾		—		2,115
Other		1.8	%			313		300
					$	21,432	$	29,404

(1)	As of December 31, 2018, noncontrolling interest was 12.5%

Falcon Global Holdings. On February 8, 2018, a wholly-owned subsidiary of SEACOR Marine and MOI formed and capitalized a joint venture named Falcon Global Holdings LLC to operate the Company’s liftboat fleet. In connection therewith and MOI’s plan of reorganization, which was confirmed on January 18, 2018, MOI emerged from its Chapter 11 bankruptcy case. In accordance with the terms of a Joint Venture Contribution and Formation Agreement, the Company and MOI contributed certain liftboat vessels and other related assets to FGH and its designated subsidiaries and FGH and its designated subsidiaries assumed certain operating liabilities and indebtedness associated with the liftboat vessels and related assets. The transaction consolidates the 15 liftboat vessels operated by the Company and six liftboat vessels previously operated by MOI. The total capital contributed to FGH was approximately $112.5 million of which, $43.3 million was transferred from FGI and $18.8 million was contributed by MOI and recorded at fair value, with the remaining capital contributed by the Company. The Company consolidates FGH as the Company holds 72% of the equity interest in FGH and is entitled to appoint a majority of the board of managers of FGH.

During the year ended December 31, 2019, the net loss of FGH was $21.0 million, of which $5.9 million was attributable to noncontrolling interest. As of December 31, 2019, the net assets of FGH were $77.2 million.

Windcat Workboats. Prior to January 25, 2019, Seabulk Overseas, a wholly-owned subsidiary of the Company, owned 87% of Windcat Workboats. On January 25, 2019, Seabulk Overseas acquired 6.25% minority interest in Windcat Workboats that it did not previously own. Seabulk Overseas acquired the remaining 6.25% interest in Windcat Workboats that the Company did not already own on March 15, 2019. As of December 31, 2018, the net assets of Windcat Workboats was $16.9 million. During the year ended December 31, 2018, the net loss of Windcat Workboats was $3.1 million, of which $0.4 million was attributable to noncontrolling interests.

Major Customers and Segment Information (Tables)

12 Months Ended

Dec. 31, 2019

Segment Reporting [Abstract]

Schedule of Segment Reporting Information, by Segment

The following tables summarize (in thousands) the operating results and property and equipment of the Company’s reportable segments. Direct vessel profit is the Company’s measure of segment profitability, a key metric in assessing the performance of its fleet. Direct vessel profit is defined as operating revenues less direct operating expenses excluding leased-in equipment expense. The Company utilizes direct vessel profit as its primary financial measure to analyze and compare the operating performance of its individual vessels, fleet categories, regions and combined fleet.

	United States (primarily Gulf of Mexico)			Africa (primarily West Africa)			Middle East and Asia			Latin America			Europe Continuing Operations			Total
For the year ended December 31, 2019
Operating Revenues:
Time charter	$	38,955		$	44,160		$	54,312		$	11,460		$	33,414		$	182,301
Bareboat charter		1,562			—			—			3,569			—			5,131
Other		3,806			1,461			1,669			1,390			5,734			14,060
		44,323			45,621			55,981			16,419			39,148			201,492
Direct Costs and Expenses:
Operating:
Personnel		17,491			13,833			16,698			4,459			13,031			65,512
Repairs and maintenance		7,583			4,701			7,182			1,348			3,855			24,669
Drydocking		4,594			490			600			161			3			5,848
Insurance and loss reserves		2,370			1,051			1,449			311			857			6,038
Fuel, lubes and supplies		2,936			3,471			2,904			1,056			960			11,327
Other		393			4,354			3,095			1,182			1,307			10,331
		35,367			27,900			31,928			8,517			20,013			123,725
Direct Vessel Profit	$	8,956		$	17,721		$	24,053		$	7,902		$	19,135			77,767
Other Costs and Expenses:
Operating:
Leased-in equipment	$	10,894		$	3,090		$	173		$	10		$	1,991			16,158
Administrative and general																	44,726
Depreciation and amortization	$	21,947		$	10,404		$	16,400		$	6,205		$	9,056			64,012
																	124,896
Losses on Asset Dispositions and Impairments, Net																	(5,397	)
Operating Loss																$	(52,526	)
As of December 31, 2019
Property and Equipment:
Historical cost	$	297,392		$	207,107		$	292,446		$	57,534		$	122,499		$	976,978
Accumulated depreciation		(157,514	)		(57,136	)		(73,039	)		(16,239	)		(55,034	)		(358,962	)
	$	139,878		$	149,971		$	219,407		$	41,295		$	67,465		$	618,016
Total Assets⁽¹⁾	$	224,229		$	161,915		$	250,890		$	116,736		$	109,874		$	863,644

(1)	Total assets exclude $145,232 thousand of corporate assets.

	United States (primarily Gulf of Mexico)			Africa (primarily West Africa)			Middle East and Asia			Latin America			Europe Continuing Operations			Total
For the year ended December 31, 2018
Operating Revenues:
Time charter	$	38,802		$	43,847		$	50,072		$	17,343		$	22,286		$	172,350
Bareboat charter		—			—			—			4,635			—			4,635
Other		14,762			7,661			(887	)		1,554			3,492			26,582
		53,564			51,508			49,185			23,532			25,778			203,567
Direct Costs and Expenses:
Operating:
Personnel		18,708			16,538			16,806			4,399			10,862			67,313
Repairs and maintenance		5,152			6,330			11,172			1,011			3,368			27,033
Drydocking		1,957			2,085			1,362			128			2,261			7,793
Insurance and loss reserves		2,922			1,096			1,371			495			459			6,343
Fuel, lubes and supplies		3,568			3,826			4,027			1,225			863			13,509
Other		393			4,313			3,980			1,130			467			10,283
		32,700			34,188			38,718			8,388			18,280			132,274
Direct Vessel Profit	$	20,864		$	17,320		$	10,467		$	15,144		$	7,498			71,293
Other Costs and Expenses:
Operating:
Leased-in equipment	$	8,240		$	4,281		$	224		$	5		$	489			13,239
Administrative and general																	46,454
Depreciation and amortization	$	23,227		$	10,453		$	18,762		$	7,908		$	8,491			68,841
																	128,534
Losses on Asset Dispositions and Impairments, Net																	(11,268	)
Operating Loss																$	(68,509	)
As of December 31, 2018
Property and Equipment:
Historical cost	$	432,336		$	184,361		$	306,897		$	124,177		$	68,812		$	1,116,583
Accumulated depreciation		(224,737	)		(55,206	)		(81,378	)		(57,002	)		(43,076	)		(461,399	)
	$	207,599		$	129,155		$	225,519		$	67,175		$	25,736		$	655,184
Total Assets⁽¹⁾	$	351,748		$	140,335		$	260,002		$	137,983		$	18,217		$	908,285

(1)	Total assets exclude $153,151 thousand of corporate assets, and $41,502 thousand of assets held-for-sale.

	United States (primarily Gulf of Mexico)			Africa (primarily West Africa)			Middle East and Asia			Latin America			Europe Continuing Operations			Total
For the year ended December 31, 2017
Operating Revenues:
Time charter	$	18,079		$	32,866		$	33,410		$	2,977		$	22,990		$	110,322
Bareboat charter		—			—			—			4,636			—			4,636
Other		4,217			1,080			474			552			2,140			8,463
		22,296			33,946			33,884			8,165			25,130			123,421
Direct Costs and Expenses:
Operating:
Personnel		15,621			13,419			16,883			809			7,881			54,613
Repairs and maintenance		3,594			5,957			9,037			274			2,462			21,324
Drydocking		1,828			2,180			968			—			—			4,976
Insurance and loss reserves		3,286			677			1,444			316			306			6,029
Fuel, lubes and supplies		1,485			2,815			3,727			223			496			8,746
Other		249			3,319			5,240			117			208			9,133
		26,063			28,367			37,299			1,739			11,353			104,821
Direct Vessel Profit (Loss)	$	(3,767	)	$	5,579		$	(3,415	)	$	6,426		$	13,777			18,600
Other Costs and Expenses:
Operating:
Leased-in equipment	$	8,709		$	4,317		$	1,092		$	5		$	326			14,449
Administrative and general																	49,865
Depreciation and amortization	$	22,060		$	9,280		$	17,724		$	3,608		$	7,635			60,307
																	124,621
Losses on Asset Dispositions and Impairments, Net																	(23,623	)
Operating Loss																$	(129,644	)
As of December 31, 2017
Property and Equipment:
Historical cost	$	410,475		$	192,600		$	326,378		$	72,484		$	56,367		$	1,058,304
Accumulated depreciation		(230,636	)		(57,228	)		(100,435	)		(37,281	)		(34,312	)		(459,892	)
	$	179,839		$	135,372		$	225,943		$	35,203		$	22,055		$	598,412
Total Assets⁽¹⁾	$	310,675		$	140,173		$	234,471		$	103,135		$	13,650		$	802,104

(1)	Total assets exclude $169,346 thousand of corporate assets, and $37,054 thousand of assets held-for-sale.

Nature of Operations and Accounting Policies - Additional Information (Details)

12 Months Ended

Dec. 02, 2019

Vessel

Jan. 01, 2019

USD ($)

Jan. 01, 2018

USD ($)

Dec. 31, 2019

USD ($)

Segment

Vessel

Dec. 31, 2018

USD ($)

Dec. 31, 2017

USD ($)

Dec. 20, 2018

Dec. 31, 2016

USD ($)

Nature Of Operations And Accounting Policies [Line Items]

Number of reportable segments | Segment

Contract with customer, liability

49.00%

$ 4,786,000

$ 1,327,000

$ 10,104,000

$ 6,953,000

Prepaid management fees

5,327,000

1,460,000

Inventory reserves

Capitalized interest costs, including allowance for funds used during construction, total

618,016,000

655,184,000

598,412,000

1,500,000

2,400,000

3,600,000

Impairment of long-lived assets held-for-use

12,000,000

14,600,000

27,500,000

Equity method investment, other than temporary impairment

$ 0

$ 1,200,000

$ 8,800,000

Incremental common shares attributable to conversion of debt securities, total | shares

1,826,966

2,183,708

4,070,500

Operating Lease, Right-of-Use Asset

$ 17,313,000

Operating Lease, Liability

24,921,000

Deferred taxes

$ 77,819,000

$ 76,712,000

Change in Accounting Principle for Unamortized Deferred Gains

Nature Of Operations And Accounting Policies [Line Items]

Deferred gain net

$ 11,000

Deferred taxes

2,300

Accounting Standards Update 2016-02

Nature Of Operations And Accounting Policies [Line Items]

Operating Lease, Right-of-Use Asset

33,700,000

Operating Lease, Liability

31,900,000

Accounting Standards Update 2016-02 | Change in Accounting Principle for Equipment, Office and Land Leases

Nature Of Operations And Accounting Policies [Line Items]

Cumulative effect on retained earnings, net of tax

1,700,000

Accounting Standards Update 2016-02 | Change in Accounting Principle for Unamortized Deferred Gains

Nature Of Operations And Accounting Policies [Line Items]

Cumulative effect on retained earnings, net of tax

$ 8,700,000

Accounting Standards Update 2016-16

Nature Of Operations And Accounting Policies [Line Items]

Cumulative effect on retained earnings, net of tax

$ 12,100,000

Performance Share Awards

Nature Of Operations And Accounting Policies [Line Items]

Number of shares issued | shares

109,600

Number of shares outstanding | shares

91,600

Restricted Stock

Nature Of Operations And Accounting Policies [Line Items]

Antidilutive securities excluded from computation of earnings per share, amount | shares

303,609

192,346

Employee Stock Option

Nature Of Operations And Accounting Policies [Line Items]

Antidilutive securities excluded from computation of earnings per share, amount | shares

913,569

805,566

Continuing Operations

Nature Of Operations And Accounting Policies [Line Items]

Depreciation, total

$ 64,000,000

$ 68,800,000

$ 60,300,000

Discontinued Operations

Nature Of Operations And Accounting Policies [Line Items]

Depreciation, total

3,500,000

3,400,000

2,500,000

Prepaid Vessel Management Fees

24,300,000

Nature Of Operations And Accounting Policies [Line Items]

Prepaid management fees

2,000,000

Geographic Distribution, Domestic

Nature Of Operations And Accounting Policies [Line Items]

Contract with customer, liability

4,800,000

Geographic Distribution, Foreign

Nature Of Operations And Accounting Policies [Line Items]

Contract with customer, liability

$ 1,800,000

Minimum

Nature Of Operations And Accounting Policies [Line Items]

Minimum | SEACOR Marine Foreign Holdings

20.00%

Nature Of Operations And Accounting Policies [Line Items]

Nature Of Operations And Accounting Policies [Line Items]

50.00%

Maximum

Nature Of Operations And Accounting Policies [Line Items]

50.00%

CME

Noncontrolling interest, ownership percentage by noncontrolling owners

51.00%

MexMar

Nature Of Operations And Accounting Policies [Line Items]

Nature Of Operations And Accounting Policies [Line Items]

49.00%

SMI

Nature Of Operations And Accounting Policies [Line Items]

49.00%

MEXMAR Offshore

Nature Of Operations And Accounting Policies [Line Items]

^[1]

49.00%

SEACOSCO

Nature Of Operations And Accounting Policies [Line Items]

50.00%

Latin America

Number of vessels | Vessel

Number of vessels joint ventured | Vessel

Nature Of Operations And Accounting Policies [Line Items]

$ 41,295,000

67,175,000

35,203,000

Europe

Number of vessels | Vessel

Number of vessels joint ventured | Vessel

Number of non-wind farm vessels | Vessel

Schedule of Noncontrolling Interests in the Company's Consolidated Subsidiaries

$ 67,465,000

$ 25,736,000

$ 22,055,000

[1]	This joint venture holds the investment in UP Offshore

Fair Value Measurements - Schedule of Estimated Fair Values of Financial Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Reported Value Measurement
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash, cash equivalents and restricted cash	$ 87,047	$ 93,254
Investments, at cost, in 50% or less owned companies (included in other assets)	132	132
Long-term debt, including current portion	398,053	404,666
Estimate of Fair Value Measurement \| Fair Value, Inputs, Level 1
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash, cash equivalents and restricted cash	87,047	93,254
Estimate of Fair Value Measurement \| Fair Value, Inputs, Level 2
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Long-term debt, including current portion	$ 380,815	$ 388,949

Nature of Operations and Accounting Policies - Schedule Of Deferred Revenues (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Nature Of Operation And Accounting Policies [Abstract]
Balance at beginning of year	$ 1,327	$ 10,104	$ 6,953
Revenues deferred during the year	8,164	3,600	4,699
Revenues recognized during the year	(4,705)	(12,377)	(1,548)
Balance at end of year	$ 4,786	$ 1,327	$ 10,104

Noncontrolling Interests in Subsidiaries (Tables)

12 Months Ended

Dec. 31, 2019

Noncontrolling Interest [Abstract]

Noncontrolling interests in the Company’s consolidated subsidiaries as of December 31 were as follows (in thousands):

	Noncontrolling Interests				2019		2018
Falcon Global Holdings		28.0	%		$	21,119	$	26,989
Windcat Workboats		—		⁽¹⁾		—		2,115
Other		1.8	%			313		300
					$	21,432	$	29,404

Nature of Operations and Accounting Policies - Schedule of Accumulated Other Comprehensive Loss (Parenthetical) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2017 USD ($)
Nature Of Operation And Accounting Policies [Abstract]
Effective income tax rate reconciliation, change in enacted tax rate, amount	$ 4.5

Investments, at Equity, and Advances to 50% or Less Owned Companies - Schedule of Equity Investments (Details) - USD ($)
$ in Thousands

12 Months Ended

Dec. 31, 2019

Dec. 31, 2018

Dec. 31, 2017

Dec. 20, 2018

49.00%

$ 105,221

$ 121,773

Minimum

20.00%

Maximum

50.00%

MexMar

49.00%

$ 54,249

53,840

SeaCosco Offshore LLC

50.00%

$ 23,926

28,002

OSV Partners

30.40%

$ 10,669

11,087

SEACOR Marlin LLC

49.00%

$ 7,929

7,579

MEXMAR Offshore

^[1]

49.00%

^[1]

4,900

Offshore Vessel Holdings

49.00%

$ 4,052

4,900

Dynamic Offshore

19.00%

$ 0

2,263

Nautical Power

Other Offshore Marine Services Joint Ventures

50.00%

Other Offshore Marine Services Joint Ventures | Minimum

$ 4,396

9,202

Other Offshore Marine Services Joint Ventures | Maximum

20.00%

All Other Excluding MexMar, Falcon Global, Sea-Cat Crewzer and Sea-Cat Crewzer II

50.00%

Current assets

$ 108,238

99,400

Noncurrent assets

618,745

567,628

Current liabilities

106,742

59,912

Noncurrent liabilities

338,836

325,700

Operating and administrative

142,327

109,636

$ 147,360

119,767

77,952

78,025

Depreciation

28,800

26,443

30,499

Costs and expenses

148,567

104,395

108,524

Loss on Asset Dispositions and Impairments, Net

(166)

(89)

Operating Income

(6,406)

5,152

38,836

Net (Loss) Income

$ (36,341)

$ (13,945)

$ 13,189

[1]	This joint venture holds the investment in UP Offshore

Savings and Multi-employer Pension Plans - Additional Information (Details) $ in Thousands, € in Millions, £ in Millions		3 Months Ended		12 Months Ended
	Jan. 01, 2019	Jun. 30, 2018 USD ($)	Jun. 30, 2018 EUR (€)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2014 USD ($)	Nov. 07, 2018 GBP (£)	Dec. 31, 2015 USD ($)	Dec. 31, 2013 USD ($)
Pension And Other Postretirement Benefits Disclosure [Line Items]
Defined contribution plan, employer matching contribution, percent of employees' gross pay	1.00%
Defined Contribution Plan, Maximum Annual Contributions Per Employee, Amount				$ 300
Other Defined Contribution Plan
Pension And Other Postretirement Benefits Disclosure [Line Items]
Defined contribution plan, cost				300	$ 200	$ 200
United Kingdom Merchant Navy Officers Pension Fund \| Foreign Pension Plan
Pension And Other Postretirement Benefits Disclosure [Line Items]
Pension and other postretirement benefits cost (reversal of cost), total							$ 19,400
Pension and other postretirement benefits invoice										$ 2,600
Pension and other post-retirement benefit plans, total funding deficit \| £								£ 9.0
Liability, defined benefit pension plan, current				300
Liability, defined benefit pension plan, noncurrent				$ 700
Merchant Navy Ratings Pension Fund
Pension And Other Postretirement Benefits Disclosure [Line Items]
Multiemployer plan, contributions by employer		$ 1,190	€ 0.9
Merchant Navy Ratings Pension Fund \| Foreign Pension Plan
Pension And Other Postretirement Benefits Disclosure [Line Items]
Pension and other post-retirement benefit plans, total funding deficit									$ 6,900

Income Taxes

12 Months Ended

Dec. 31, 2019

Income Tax Disclosure [Abstract]

Income Taxes

9.	INCOME TAXES

In late 2017, the U.S. Tax Cuts and Jobs Act (the “Tax Act”) was enacted into law. This law significantly impacted our corporate income taxes commencing in 2018 and will continue to do so in future years. The most significant provisions included reducing the corporate tax rate from 35% to 21%; eliminating U.S. federal tax on dividends from foreign subsidiaries, creating a limitation on deductible interest expense, further restricting the compensation deduction, and changing the utilization of Net Operating Losses (“NOL’s”).

In arriving at the 2019 results the Company took into account the impacts of the Tax Act based on our interpretation of the provisions enacted and the proposed regulations issued as of this date

Loss before income tax benefit and equity in earnings (losses) of 50% or less owned companies derived from U.S. and foreign companies for the years ended December 31 were as follows (in thousands):

	2019			2018			2017
United States	$	(71,833	)	$	(72,540	)	$	(90,696	)
Foreign		(22,025	)		(29,466	)		(45,879	)
Eliminations		11,022			8,782			18,785
	$	(82,836	)	$	(93,224	)	$	(117,790	)

The components of income tax expense (benefit) for the years ended December 31 were as follows (in thousands):

	2019			2018			2017
Current:
Federal	$	(6	)	$	5,987		$	(16,705	)
State		(78	)		3			(42	)
Foreign		5,039			3,393			3,343
		4,955			9,383			(13,404	)
Deferred:
Federal		(12,594	)		(21,466	)		(60,750	)
State		(224	)		(1,404	)		(172	)
Foreign		(49	)		133			(84	)
		(12,867	)		(22,737	)		(61,006	)
	$	(7,912	)	$	(13,354	)	$	(74,410	)

For the year ending December 31, 2019, the Company has recorded a return to provision adjustment related to losses from a consolidated joint venture for the 2018 tax year. The resulting additional liability of $2.3 million was recorded in the Company’s financial statements during the third quarter of 2019.

For 2018, the Company incurred a current tax liability of $1.4 million related to the non-qualified withdrawal of funds from a Capital Construction Fund (“CCF”) by a partnership in which the Company held a 50% interest. The Company had previously recorded a deferred tax liability in connection with this CCF fund.

As of December 31, 2017, the Company’s net operating loss carryforwards excluded potential tax benefits of $3.9 million as a result of uncertainty regarding interpretation of the Tax Act. Subsequent guidelines have confirmed that the Company should recognize the tax benefits of $3.9 million and therefore, for the year ending December 31, 2018, the Company removed the uncertain tax position previously established against the net operating loss carryforwards.

During the preparation of the 2017 federal income tax return, the Company’s management realized that they had overestimated the available foreign taxes that could be credited against the 2017 transition tax. This resulted in an additional tax liability of $3.4 million on its 2017 federal income tax return. This additional liability was recorded as a return-to-provision adjustment to tax expense during the year ended December 31, 2018.

The following table reconciles the difference between the statutory federal income tax rate for the Company and the effective income tax rate for the years ended December 31:

	2019			2018			2017
Statutory rate		(21.0	)%		(21.0	)%		(35.0	)%
U.S. federal income tax law changes		—	%		—	%		(37.3	)%
SEACOR Holdings share awards to Company personnel		—	%		0.2	%		2.3	%
Non-deductible expenses		—	%		—	%		1.8	%
Exclusion of foreign subsidiaries with accumulated losses and withholding tax		7.2	%		9.5	%		3.1	%
Noncontrolling interests		1.8	%		(1.5	)%		1.7	%
State taxes		(0.3	)%		(1.5	)%		(0.2	)%
Return to provision		2.9	%		(0.5	)%		0.4	%
Other		(0.2	)%		0.5	%		—	%
Effective Tax Rate		(9.6	)%		(14.3	)%		(63.2	)%

For the year ending December 31, 2019, the Company’s effective income tax rate of 9.6% was lower than the statutory tax rate of 21% primarily due to foreign subsidiaries with current losses for which there is no current or future federal income tax benefit, reducing the statutory tax rate by 7.2%, and noncontrolling interests reducing the tax rate by 1.8%

For the year ending December 31, 2018, the Company’s effective income tax rate of 14.3% was lower than the Company’s statutory tax rate of 21% primarily due to foreign subsidiaries with current losses for which there is no current or future federal income tax benefit.

For the year ending December 31, 2017, the Company’s effective income tax rate of 63.2% was higher than the Company’s statutory tax rate of 35% primarily due to income tax benefits of $43.7 million recognized as a result of the Tax Act. The majority of the income tax benefits recognized were due to a reduction in U.S. tax rates from 35% to 21% applied to the Company’s domestic basis differences and the elimination of previously accrued deferred taxes on the unremitted earnings of the Company’s foreign subsidiaries.

The components of net deferred income tax liabilities as of December 31 were as follows (in thousands):

	2019			2018
Deferred tax liabilities:
Property and equipment	$	63,827		$	65,880
Investments in 50% or Less Owned Companies		3,039			3,040
Other		10,953			7,792
Total deferred tax liabilities		77,819			76,712
Deferred tax assets:
Federal Net Operating Loss Carryforwards		28,664			20,974
Other		16,561			11,677
		45,225			32,651
Valuation Allowance		(1,311	)		(624	)
Total deferred tax assets		43,914			32,027
Net deferred tax liabilities	$	33,905		$	44,685

The Section 163(j) interest deduction limitations were amended to limit the ability of the Company to deduct net interest expense to thirty percent of adjusted taxable income. For the year ended December 31, 2019, $6.6 million of interest expense was suspended, and for the year ended December 31, 2018, $3.6 million of interest expense was suspended, resulting in a total interest expense amount available for carry forward of $10.2 million. This amount will be available to be deducted in future years subject to the 30% limitation. Future utilization of NOL’s arising in tax years after December 31, 2017 are limited to eighty percent of taxable income and are allowed to be carried forward indefinitely. As of December 31, 2019, the Company has $42.2 million of net operating losses generated prior to December 31, 2017 and $94.5 million of net operating losses generated after 2017. Net operating losses generated in 2017 may carry forward 20 years (expiring in 2037). The 2018 and 2019 NOLs will carry forward indefinitely with no expiration period but its utilization will be subject to an annual 80 percent of taxable income limitation.

As of December 31, 2019, the Company's valuation allowance of $1.3 million related primarily to Louisiana state net operating loss carryforwards.

Long Term Debt - Additional Information (Details)										1 Months Ended	9 Months Ended		12 Months Ended
Long Term Debt - Additional Information (Details)	Dec. 18, 2019 USD ($)	Dec. 20, 2018 USD ($)	Sep. 28, 2018 USD ($) Vessel	Sep. 26, 2018 USD ($)	Jul. 05, 2018 USD ($)	May 02, 2018 USD ($) $ / shares shares	Feb. 08, 2018 USD ($)	Nov. 03, 2017 USD ($)	Apr. 28, 2017 Catamaran	Apr. 30, 2018 USD ($) $ / shares shares	Sep. 30, 2019	Dec. 31, 2017 USD ($)	Dec. 31, 2019 USD ($) EUR (€) Tranche	Dec. 31, 2018 USD ($)	Dec. 31, 2018 EUR (€)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2016 EUR (€)	Oct. 31, 2018 USD ($)	Mar. 31, 2017 USD ($)	May 24, 2016 EUR (€)	Apr. 21, 2016 EUR (€)	Dec. 01, 2015 USD ($) $ / shares	Aug. 03, 2015 USD ($)
Debt Instrument [Line Items]
Debt instrument, increase (decrease), net, total				$ 30,100,000										$ 1,000,000
Loss on extinguishment of debt														638,000
Contributed capital		$ 10,000,000
Debt instrument unamortized discount													$ 26,343,000	32,005,000
Repayments of long-term debt, total													23,974,000	49,405,000		$ 11,926,000
Long-Term Debt														$ 106,640,000
Equity method investment, ownership percentage		49.00%
Long-term Debt Obligation
Debt Instrument [Line Items]
Letters of credit outstanding, amount													$ 500,000
Minimum
Debt Instrument [Line Items]
Equity method investment, ownership percentage													20.00%
Maximum
Debt Instrument [Line Items]
Equity method investment, ownership percentage													50.00%
Falcon Global Holdings
Debt Instrument [Line Items]
Noncontrolling Interest, ownership percentage by parent							72.00%							72.00%
Falcon Global USA LLC
Debt Instrument [Line Items]
Payments for debtor in possession obligations							$ 15,000,000
Carlyle Group
Debt Instrument [Line Items]
Convertible debt, total																							$ 175,000,000
Carlyle Group \| Maximum
Debt Instrument [Line Items]
Convertible debt, total												$ 50,000,000				50,000,000
Convertible Senior Notes Converted to Warrants \| Carlyle Group
Debt Instrument [Line Items]
Debt instrument, convertible, conversion ratio						37.73				37.73
Debt instrument, face amount						$ 1,000				$ 1,000
Class of warrant or right, exercise price of warrants or rights \| $ / shares						$ 0.01				$ 0.01
Debt conversion, original debt, amount						$ 50,000,000				$ 50,000,000
Debt conversion, converted instrument, shares issued \| shares						1,886,792				1,900,000
Debt instrument, convertible, conversion price \| $ / shares						$ 26.50				$ 26.50
Conversion Revolving Credit Facility from Windcat Workboats
Debt Instrument [Line Items]
Debt conversion, original debt, amount \| €															€ 6,000,000
Carlyle Warrants
Debt Instrument [Line Items]
Class of warrant or right, exercise price of warrants or rights \| $ / shares																							$ 0.01
Warrants and rights outstanding, term						25 years
OSV Partners
Debt Instrument [Line Items]
Contributed capital			$ 5,000,000													2,300,000
Investment in affiliates, amount of preferred equity offering participated			5,000,000
Payments to acquire interest in subsidiaries and affiliates, total	$ 1,100,000		1,100,000
Commitment to invest additional funds if call by general partner			1,100,000
Payments to acquire loans receivable			$ 2,100,000
Revenue from related parties													$ 0	$ 600,000		600,000
Equity method investment, ownership percentage													30.40%
OSV Partners \| General Partner
Debt Instrument [Line Items]
Contributed capital																$ 6,000,000
Equity method investment, ownership percentage													38.60%
OSV Partners \| Offshore Support Vessels
Debt Instrument [Line Items]
Number of equipment operated \| Vessel			5
Falcon Global
Debt Instrument [Line Items]
Business acquisition, percentage of voting interests acquired																				100.00%
Sea-Cat Crewzer II
Debt Instrument [Line Items]
Number of equipment operated \| Catamaran									2
Repayments of long-term debt, total			$ 19,100,000											1,800,000
Business acquisition, percentage of voting interests acquired									100.00%
Equity method investment, ownership percentage									50.00%
Sea-Cat Crewzer
Debt Instrument [Line Items]
Debt instrument, interest rate												1.52%				1.52%
Debt instrument, interest rate, effective percentage												5.64%				5.64%
Number of equipment operated \| Catamaran									2
Repayments of long-term debt, total			16,900,000											$ 1,600,000		$ 1,100,000
Payments of debt issuance costs																100,000
Business acquisition, percentage of voting interests acquired									100.00%
Equity method investment, ownership percentage									50.00%
Debt instrument, final baloon payment												$ 15,300,000				$ 15,300,000
Sea-Cat Crewzer \| Minimum
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate																2.10%
Sea-Cat Crewzer \| Maximum
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate																2.75%
SEACOR Alps
Debt Instrument [Line Items]
Debt instrument, interest rate											5.00%
Percentage of amount of loan financed											70.00%
Debt instrument, maturity period											2023
Loan Facility With DNB Bank ASA
Debt Instrument [Line Items]
Debt instrument, maturity period				2023
Line of credit facility, maximum borrowing capacity				$ 130,000
Debt instrument, interest rate, effective percentage				5.875%
Debt instrument, periodic payment, principal				$ 3,300,000
Loan Facility With DNB Bank ASA \| Interest Rate Swap
Debt Instrument [Line Items]
Derivative, notional amount																			$ 65,000,000
Other DNB Credit Facilities
Debt Instrument [Line Items]
Repayments of lines of credit				101,300,000
Long-term debt, total				99,900,000
Interest payable				1,400,000
Loss on extinguishment of debt				$ 600,000
Convertible Senior Notes 3.75%
Debt Instrument [Line Items]
Debt instrument, interest rate						4.25%				4.25%													3.75%
Convertible debt, total						$ 125,000,000				$ 125,000,000													$ 175,000,000
Debt instrument, convertible, conversion ratio														23.26	23.26
Debt instrument, face amount														$ 1,000
Three Point Seven Five Percentage Convertible Notes
Debt Instrument [Line Items]
Debt instrument, interest rate, effective percentage														7.95%
Embedded derivative, fair value of embedded derivative liability																							$ 27,300,000
FGUSA Credit Facility
Debt Instrument [Line Items]
Debt agreement maximum borrowing capacity							131,100,000
Debt instrument unamortized discount							10,000,000
FGUSA Credit Facility \| Revolving Credit Facility
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity							15,000,000
Debt instrument, interest rate, effective percentage													6.3125%
Debt instrument unamortized discount							500,000
Proceeds from lines of credit, total														$ 15,000,000
FGUSA Credit Facility \| Term Loan
Debt Instrument [Line Items]
Long-term debt, total							116,100,000
Debt instrument, periodic payment, principal														7,000,000
Debt instrument unamortized discount							$ 9,500,000
Sea-Cat Crewzer III
Debt Instrument [Line Items]
Debt instrument, interest rate, effective percentage												2.76%				2.76%
Debt instrument, face amount \| €																						€ 27,600,000
Proceeds from issuance of debt																$ 7,100,000	$ 22,800,000
Debt issuance costs, gross																	2,700,000
Repayments of long-term debt, total														$ 3,100,000		600,000
Windcat Workboats Facilities
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity \| €																					€ 25,000,000
Proceeds from lines of credit, total																	23,500,000	€ 21,000,000
Debt issuance costs, gross																	600,000
Repayments of long-term debt, total																	$ 22,900,000
Line of credit facility, collateral description														Windcat Workboats entered into a €25.0 million revolving credit facility secured by 38 of the Company’s CTV fleet.	Windcat Workboats entered into a €25.0 million revolving credit facility secured by 38 of the Company’s CTV fleet.
Debt instrument, maturity year														2021	2021
Windcat Workboats Facilities \| Minimum
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate																	3.00%	3.00%
Line of credit facility, unused capacity, commitment fee percentage																	1.20%	1.20%
Windcat Workboats Facilities \| Maximum
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate																	3.30%	3.30%
Line of credit facility, unused capacity, commitment fee percentage																	1.32%	1.32%
Euro Debt
Debt Instrument [Line Items]
Repayments of long-term debt, total														$ 7,500,000
Pound Sterling Debt
Debt Instrument [Line Items]
Proceeds from issuance of long-term debt, total														8,500,000
Term Loan to Acquire Two Vessels
Debt Instrument [Line Items]
Debt instrument, interest rate, effective percentage					5.5625%
Debt instrument, face amount					$ 11,000,000
Debt instrument, maturity year													2023
Claims recoverable amount under borrowings					$ 5,500,000
Claims recoverable under borrowings percentage of obligations outstanding					50.00%
Term Loan to Acquire Two Vessels \| Interest Rate Swap
Debt Instrument [Line Items]
Derivative, notional amount																			$ 5,500,000
BNDES Equipment Construction Finance Notes
Debt Instrument [Line Items]
Debt instrument, interest rate, effective percentage													4.00%
Repayments of long-term debt, total													$ 2,000,000	2,000,000		$ 2,000,000
Debt instrument maturity date description													July through October 2021
Falcon Global
Debt Instrument [Line Items]
Debt issuance costs, gross																				$ 1,000,000
Repayments of long-term debt, total			$ 51,900,000									$ 4,400,000		$ 3,000,000
Number of foreign-flag liftboats to be constructed under term loan \| €													2
Number of tranches \| Tranche													2
Debt instrument repayment term													5 years
Debt instrument, maturity date													Jun. 30, 2022
Payments of debt issuance costs								$ 200,000
Long-Term Debt																				$ 58,300,000
Tranche A \| Falcon Global
Debt Instrument [Line Items]
Debt instrument, face amount																								$ 62,500,000
Tranche B \| Falcon Global
Debt Instrument [Line Items]
Debt instrument, face amount																								$ 18,000,000
Sea-Cat Crewzer II
Debt Instrument [Line Items]
Debt instrument, interest rate												1.52%				1.52%
Debt instrument, interest rate, effective percentage												5.64%				5.64%
Repayments of long-term debt, total																$ 1,200,000
Payments of debt issuance costs																100,000
Debt instrument, final baloon payment												$ 17,300,000				$ 17,300,000
Sea-Cat Crewzer II \| Minimum
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate																2.10%
Sea-Cat Crewzer II \| Maximum
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate																2.75%

Major Customers and Segment Information - Schedule of Segment Reporting Information, by Segment (Details) - USD ($)
$ in Thousands

3 Months Ended

12 Months Ended

Dec. 31, 2019

Sep. 30, 2019

Jun. 30, 2019

Mar. 31, 2019

Dec. 31, 2018

Sep. 30, 2018

Jun. 30, 2018

Mar. 31, 2018

Dec. 31, 2019

Dec. 31, 2018

Dec. 31, 2017

$ 49,070

$ 54,700

$ 52,812

$ 44,910

$ 58,897

$ 58,169

$ 47,871

$ 38,630

$ 201,492

$ 203,567

$ 123,421

123,725

132,274

104,821

Administrative and general

77,767

71,293

18,600

44,726

46,454

49,865

Losses on Asset Dispositions and Impairments, Net

64,012

68,841

60,307

Other Costs and Expenses

124,896

128,534

124,621

(5,397)

(11,268)

(23,623)

Operating Loss

(10,497)

$ (3,355)

$ (17,640)

$ (21,034)

(11,253)

$ (12,207)

$ (20,842)

$ (24,206)

(52,526)

(68,509)

(129,644)

976,978

^[1]

1,116,583

^[1]

976,978

^[1]

1,116,583

^[1]

1,058,304

(358,962)

(461,399)

(358,962)

(461,399)

(459,892)

618,016

655,184

618,016

655,184

598,412

863,644

^[2]

908,285

^[3]

863,644

^[2]

908,285

^[3]

802,104

^[4]

Leased In Equipment

16,158

13,239

14,449

Time Charter

182,301

172,350

110,322

Bareboat Charter

5,131

4,635

4,636

Other Marine Services

14,060

26,582

8,463

Personnel

65,512

67,313

54,613

Repairs and Maintenance

24,669

27,033

21,324

Drydocking

Insurance and Loss Reserves

5,848

7,793

4,976

6,038

6,343

6,029

Fuel, Lubes and Supplies

Other Direct Costs and Expenses

11,327

13,509

8,746

10,331

10,283

9,133

UNITED STATES

44,323

53,564

22,296

35,367

32,700

26,063

8,956

20,864

(3,767)

21,947

23,227

22,060

297,392

432,336

297,392

432,336

410,475

(157,514)

(224,737)

(157,514)

(224,737)

(230,636)

139,878

207,599

139,878

207,599

179,839

UNITED STATES | Leased In Equipment

224,229

^[2]

351,748

^[3]

224,229

^[2]

351,748

^[3]

310,675

^[4]

UNITED STATES | Time Charter

10,894

8,240

8,709

UNITED STATES | Bareboat Charter

38,955

38,802

18,079

UNITED STATES | Other Marine Services

1,562

UNITED STATES | Personnel

3,806

14,762

4,217

UNITED STATES | Repairs and Maintenance

17,491

18,708

15,621

UNITED STATES | Drydocking

7,583

5,152

3,594

UNITED STATES | Insurance and Loss Reserves

4,594

1,957

1,828

UNITED STATES | Fuel, Lubes and Supplies

2,370

2,922

3,286

UNITED STATES | Other Direct Costs and Expenses

2,936

3,568

1,485

393

249

Africa

45,621

51,508

33,946

27,900

34,188

28,367

17,721

17,320

5,579

10,404

10,453

9,280

207,107

184,361

207,107

184,361

192,600

(57,136)

(55,206)

(57,136)

(55,206)

(57,228)

149,971

129,155

149,971

129,155

135,372

Africa | Leased In Equipment

161,915

^[2]

140,335

^[3]

161,915

^[2]

140,335

^[3]

140,173

^[4]

3,090

4,281

4,317

Africa | Time Charter

Africa | Other Marine Services

44,160

43,847

32,866

1,461

7,661

1,080

Africa | Personnel

Africa | Repairs and Maintenance

13,833

16,538

13,419

4,701

6,330

5,957

Africa | Drydocking

Africa | Insurance and Loss Reserves

490

2,085

2,180

Africa | Fuel, Lubes and Supplies

1,051

1,096

677

Africa | Other Direct Costs and Expenses

3,471

3,826

2,815

4,354

4,313

3,319

Middle East and Asia

55,981

49,185

33,884

31,928

38,718

37,299

24,053

10,467

(3,415)

16,400

18,762

17,724

292,446

306,897

292,446

306,897

326,378

(73,039)

(81,378)

(73,039)

(81,378)

(100,435)

219,407

225,519

219,407

225,519

225,943

Middle East and Asia | Leased In Equipment

250,890

^[2]

260,002

^[3]

250,890

^[2]

260,002

^[3]

234,471

^[4]

Middle East and Asia | Time Charter

173

224

1,092

Middle East and Asia | Other Marine Services

54,312

50,072

33,410

Middle East and Asia | Personnel

1,669

(887)

474

Middle East and Asia | Repairs and Maintenance

16,698

16,806

16,883

Middle East and Asia | Drydocking

7,182

11,172

9,037

Middle East and Asia | Insurance and Loss Reserves

600

1,362

968

Middle East and Asia | Fuel, Lubes and Supplies

1,449

1,371

1,444

Middle East and Asia | Other Direct Costs and Expenses

2,904

4,027

3,727

3,095

3,980

5,240

Latin America

16,419

23,532

8,165

8,517

8,388

1,739

7,902

15,144

6,426

6,205

7,908

3,608

57,534

124,177

57,534

124,177

72,484

(16,239)

(57,002)

(16,239)

(57,002)

(37,281)

41,295

67,175

41,295

67,175

35,203

Latin America | Leased In Equipment

116,736

^[2]

137,983

^[3]

116,736

^[2]

137,983

^[3]

103,135

^[4]

Latin America | Time Charter

Latin America | Bareboat Charter

11,460

17,343

2,977

Latin America | Other Marine Services

3,569

4,635

4,636

Latin America | Personnel

1,390

1,554

552

Latin America | Repairs and Maintenance

4,459

4,399

809

Latin America | Drydocking

1,348

1,011

274

Latin America | Insurance and Loss Reserves

161

128

Latin America | Fuel, Lubes and Supplies

311

495

316

Latin America | Other Direct Costs and Expenses

1,056

1,225

223

Europe Continuing Operations

1,182

1,130

117

39,148

25,778

25,130

20,013

18,280

11,353

19,135

7,498

13,777

9,056

8,491

7,635

122,499

68,812

122,499

68,812

56,367

(55,034)

(43,076)

(55,034)

(43,076)

(34,312)

67,465

25,736

67,465

25,736

22,055

Europe Continuing Operations | Leased In Equipment

$ 109,874

^[2]

$ 18,217

^[3]

109,874

^[2]

18,217

^[3]

13,650

^[4]

Europe Continuing Operations | Time Charter

1,991

489

326

Europe Continuing Operations | Other Marine Services

33,414

22,286

22,990

Europe Continuing Operations | Personnel

5,734

3,492

2,140

Europe Continuing Operations | Repairs and Maintenance

13,031

10,862

7,881

Europe Continuing Operations | Drydocking

3,855

3,368

2,462

Europe Continuing Operations | Insurance and Loss Reserves

2,261

Europe Continuing Operations | Fuel, Lubes and Supplies

857

459

306

Europe Continuing Operations | Other Direct Costs and Expenses

960

863

496

Share Based Compensation Arrangement By Share Based Payment Award [Line Items]

$ 1,307

$ 467

$ 208

[1]	Includes property and equipment acquired in business acquisitions at acquisition date fair value, and net of the impact of recognized impairment charges.
[2]	Total assets exclude $145,232 thousand of corporate assets.
[3]	Total assets exclude $153,151 thousand of corporate assets, and $41,502 thousand of assets held-for-sale.
[4]	Total assets exclude $169,346 thousand of corporate assets, and $37,054 thousand of assets held-for-sale.

Share Based Compensation - Schedule of Restricted Stock Transactions (Details) - Restricted Stock - $ / shares

12 Months Ended

Dec. 31, 2019

Dec. 31, 2018

Outstanding as of the beginning of year (in shares)

192,346

121,693

Non-Vested, weight average grant price (in dollars per share)

$ 22.32

Granted (in shares)

245,400

^[1]

120,600

Granted, weight average grant price (in dollars per share)

$ 13.28

Vested, shares (in shares)

131,937

49,947

Vested, weight average grant price (in dollars per share)

$ 13.45

Forfeited (in shares)

2,200

Forfeited, weight average grant price (in dollars per share)

$ 17.26

Outstanding as of the end of year (in shares)

303,609

192,346

Non-Vested, weight average grant price (in dollars per share)

$ 20.46

$ 22.32

[1]	Excludes 91,600 grants of performance-based stock units that are not considered outstanding until such time that they become probable to vest.

Share Based Compensation (Tables)

12 Months Ended

Dec. 31, 2019

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Schedule of Equity Incentive Plan Transactions

The following transactions have occurred in connection with the Company’s share-based compensation under the 2017 Plan during the years ended December 31:

	2019			2018
Director Stock Awards Granted		30,197			19,285

Restricted Stock Activity:
Outstanding as of the beginning of year		192,346			121,693
Granted - 2017 Plan		245,400	⁽¹⁾		120,600
Vested		131,937			49,947
Forfeited		2,200			—
Outstanding as of the end of year		303,609			192,346

Stock Option Activity:
Outstanding as of the beginning of year		805,566			613,700
Granted - 2017 Plan		230,503			258,491
Exercised		113,750			66,625
Forfeited		8,750			—
Outstanding as of the end of year		913,569			805,566

(1)	Excludes 91,600 grants of performance-based stock units that are not considered outstanding until such time that they become probable to vest.

Schedule of Restricted Stock Transactions

During the year ended December 31, 2019, the number of shares and the weighted average grant price of restricted stock transactions were as follows:

	Restricted Stock
	Number of Shares		Weight Average Grant Price
Non-Vested as of December 31, 2018		192,346	$	22.32
Granted		245,400		13.28
Vested		131,937		13.45
Forfeited		2,200		17.26
Non-Vested as of December 31, 2019		303,609		20.46

Schedule of Stock Option Transactions

During the year ended December 31, 2019, the number of shares and the weighted average exercise price on stock option transactions were as follows:

	Stock Options
	Number of Shares		Weight Average Grant Price
Non-Vested as of December 31, 2018		805,566	$	14.81
Granted		230,503		8.73
Exercised		113,750		13.98
Forfeited		8,750		20.93
Non-Vested as of December 31, 2019		913,569		14.85
Exercisable as of December 31, 2019⁽¹⁾		408,075		14.69

(1)	The weighted average remaining contractual term is 8.23 years.

Income Taxes - Schedule of Effective Income Tax Rate Reconciliation (Details)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Effective Income Tax Rate Reconciliation, Percent [Abstract]
Statutory rate	(21.00%)	(21.00%)	(35.00%)
U.S. federal income tax law changes			(37.30%)
SEACOR Holdings share awards to Company personnel		0.20%	2.30%
Non-deductible expenses			1.80%
Exclusion of foreign subsidiaries with accumulated losses and withholding tax	7.20%	9.50%	3.10%
Noncontrolling interests	1.80%	(1.50%)	1.70%
State taxes	(0.30%)	(1.50%)	(0.20%)
Return to provision	2.90%	(0.50%)	0.40%
Other	(0.20%)	0.50%
Effective Tax Rate	(9.60%)	(14.30%)	(63.20%)

Fair Value Measurements - Schedule of Fair Value of Assets and Liabilities Measured on Recurring Basis (Details) (Parenthetical) $ in Millions	12 Months Ended
	Dec. 31, 2019 USD ($)
Fair Value Disclosures [Abstract]
Derivative, gain (loss) on derivative, net, total	$ 0.1

Equipment Acquisitions and Dispositions

12 Months Ended

Dec. 31, 2019

Property Plant And Equipment [Abstract]

Equipment Acquisitions and Dispositions

4.	EQUIPMENT ACQUISITIONS AND DISPOSITIONS

Equipment Additions. The Company’s capital expenditures and payments on equipment were $55.5 million, $51.6 million, and $69.0 million in 2019, 2018 and 2017, respectively. Deliveries of offshore support vessels for the years ended December 31 were as follows:

	2019 ⁽¹⁾		2018		2017
FSV		2		—		6
Supply		2		—		5
Liftboat		—		6		—
CTV		2		2		—
		6		8		11

(1)	Excludes three FSVs purchased from managed entities, one crew transfer vessel sold upon completion and one ERRV purchased from a joint venture.

Equipment Dispositions.

For the year ended December 31, 2019, the Company completed the sale of its ERRV fleet business, which consisted of 18 vessels with a net book value of $23.4 million. The net proceeds from the sale of the ERRV fleet, including property and equipment, were approximately $27.4 million resulting in a net loss on dispositions of $9.1 million. Additional consideration of up to £4 million (equivalent to approximately $5.2 million based on the exchange rate at the time of the sale) may be payable to the Company based on revenue targets being achieved in 2020 and 2021.

In addition to the sale of the North Sea ERRV fleet, for the year ended December 31, 2019, the Company sold five AHTS vessels, one specialty vessel previously retired and removed from service, seven FSVs, five PSVs, three liftboats, one CTV, one AHTS vessel, and other equipment and one vessel under construction for $59.4 million ($55.1 million cash and $4.3 million in cash deposits previously received) and gains of $6.6 million.

During the year ended December 31, 2018, the Company sold property and equipment for net proceeds of $17.4 million $17.3 million in cash and $0.1 million in cash deposits previously received) and recorded gains of $5.7 million, all of which were recognized at the time of sale. In addition, the Company received $4.4 million in deposits on future property and equipment sales.

During the year ended December 31, 2017, the Company sold property and equipment for net proceeds of $10.9 million and gains of $3.9 million, all of which were recognized at the time of sale. In addition, the Company received $0.1 million in deposits on future property and equipment sales.

Major equipment dispositions for the years ended December 31 were as follows:

	2019 ⁽¹⁾		2018 ⁽²⁾		2017 ⁽³⁾
AHTS		1		1		—
FSV		5		9		—
Supply		5		—		1
Crew transfer		—		1		—
Liftboats		3		2		2
		14		13		3

(1)

Excludes the sale of (i) 18 ERRV vessels from the sale of the Company North Sea Standby Safety business, (ii) one crew transfer vessel to the joint venture FRS Windcat Offshore Logistics, (iii) one FSV to the joint venture OVH, (iv) one FSV to a third party with the Company continuing to manage the vessel, (v) one ERRV from discontinued operations and (vi) six vessels that were previously removed from service (five AHTS vessels and one specialty vessel).

(2)	Excludes three ERRVs from discontinued operations

(3)	Excludes one ERRV from discontinued operations.

Income Taxes - Schedule of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Deferred tax liabilities:
Property and equipment	$ 63,827	$ 65,880
Investments in 50% or Less Owned Companies	3,039	3,040
Other	10,953	7,792
Total deferred tax liabilities	77,819	76,712
Deferred tax assets:
Federal Net Operating Loss Carryforwards	28,664	20,974
Other	16,561	11,677
Total deferred tax assets	45,225	32,651
Valuation Allowance	(1,311)	(624)
Total deferred tax assets	43,914	32,027
Net deferred tax liabilities	$ 33,905	$ 44,685

Long Term Debt - Schedule of Long-term Debt Obligations (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Long-term Debt, Gross	$ 429,823	$ 442,972
Portion due within one year	(17,802)	(16,812)
Debt discount	(26,343)	(32,005)
Issue costs	(5,427)	(6,301)
Long-term debt	380,251	387,854
Convertible Senior Notes
Debt Instrument [Line Items]
Long-term Debt, Gross	125,000	125,000
SEACOR Marine Foreign Holdings Loan Facility
Debt Instrument [Line Items]
Long-term Debt, Gross	113,750	126,750
Falcon Global USA Term Loan Facility
Debt Instrument [Line Items]
Long-term Debt, Gross	102,349	109,099
Sea-Cat Crewzer III Term Loan Facility
Debt Instrument [Line Items]
Long-term Debt, Gross	24,128	25,989
Windcat Workboats Facilities
Debt Instrument [Line Items]
Long-term Debt, Gross	24,730	24,850
Falcon Global USA Revolver
Debt Instrument [Line Items]
Long-term Debt, Gross	15,000	15,000
SEACOR 88/888 Term Loan
Debt Instrument [Line Items]
Long-term Debt, Gross	11,000	11,000
SEACOR Alps
Debt Instrument [Line Items]
Long-term Debt, Gross	10,534
BNDES Equipment Construction Finance Notes
Debt Instrument [Line Items]
Long-term Debt, Gross	$ 3,332	$ 5,284

Warrants

12 Months Ended

Dec. 31, 2019

Warrants And Rights Note Disclosure [Abstract]

Warrants

12.

WARRANTS

On April 26, 2018, the Company closed a private placement of its Common Stock and Warrants to purchase its Common Stock (which were issued to certain investors in place of Common Stock to facilitate compliance with Jones Act restrictions) for aggregate gross proceeds of $56,855,000 (the “PIPE Private Placement”) with certain qualified institutional buyers and other accredited investors. The PIPE Private Placement included the issuance of 2,168,586 shares of Common Stock (the “PIPE Shares”) and Warrants to purchase 674,164 shares of the Common Stock at an exercise price of $0.01 per share (the “PIPE Warrants”). The PIPE Warrants were issued to CME on April 26, 2018, have a 25-year term and an exercise price of $0.01 per share.

On May 2, 2018 the Company and Carlyle entered into an amendment and exchange agreement pursuant to which Carlyle exchanged $50.0 million in principal amount of the Convertible Senior Notes for warrants in order to purchase 1,886,292 shares of common stock at an exercise price of $0.01 per shares (the “Exchange Warrants” and, together with the PIPE Warrants, the “Warrants”). The Exchange Warrants have a 25-year term, which commenced May 2, 2018.

On May 31, 2018 and June 8, 2018, the 250,693 and 38,857 Warrants were exercised, respectively for a penny per share which left 2,271,406 Warrants outstanding as of December 31, 2018.

On May 28, 2019 and June 14, 2019, 380,000 and 64,440 Warrants were exercised, respectively for a penny per share which left 1,826,966 Warrants outstanding as of December 31, 2019. In connection with the exercise of Warrants on June 14, 2019, 49 shares of Common Stock were withheld as payment for the exercise price of the exercised Warrants.

Derivative Instruments and Hedging Strategies - Effect of Derivative Instruments on Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Other comprehensive income (loss), unrealized gain (loss) on derivatives arising during period, before tax	$ (1,901)	$ (1,939)	$ 214
Interest Rate Swap
Other comprehensive income (loss), unrealized gain (loss) on derivatives arising during period, before tax	(1,901)	(1,939)	214
Joint Venture Interest Rate Swap
Other comprehensive income (loss), unrealized gain (loss) on derivatives arising during period, before tax	(645)	(76)	389
Interest Expense
Reclassification of derivative gains (losses) on cash flow hedges	$ 552	$ 31	$ 118

Investments, at Equity, and Advances to 50% or Less Owned Companies

12 Months Ended

Dec. 31, 2019

Schedule Of Investments [Abstract]

Investments, at Equity, and Advances to 50% or Less Owned Companies

5.	INVESTMENTS, AT EQUITY, AND ADVANCES TO 50% OR LESS OWNED COMPANIES

Investments, at equity, and advances to 50% or less owned companies as of December 31 were as follows (in thousands):

	Ownership			2019		2018
MexMar		49.0	%	$	54,249	$	53,840
SEACOSCO		50.0	%		23,926		28,002
OSV Partners		30.4	%		10,669		11,087
SEACOR Marlin		49.0	%		7,929		7,579
MEXMAR Offshore⁽¹⁾		49.0	%		—		4,900
Offshore Vessel Holdings		49.0	%		4,052		4,900
Dynamic Offshore Drilling		19.0	%		—		2,263
Nautical Power		50.0	%		—		—
Other	20.0% — 50.0%				4,396		9,202
				$	105,221	$	121,773

(1)

^{This joint venture holds the investment in UP}^Offshore

Combined Condensed Financial Information of Other Investees. Summarized financial information of the Company’s other investees, at equity, as of and for the years ended December 31 was as follows (in thousands):

	2019		2018
Current assets	$	108,238	$	99,400
Noncurrent assets		618,745		567,628
Current liabilities		106,742		59,912
Noncurrent liabilities		338,836		325,700

	2019			2018			2017
Operating Revenues	$	142,327		$	109,636		$	147,360
Costs and Expenses:
Operating and administrative		119,767			77,952			78,025
Depreciation		28,800			26,443			30,499
		148,567			104,395			108,524
Loss on Asset Dispositions and Impairments, Net		(166	)		(89	)		—
Operating Income	$	(6,406	)	$	5,152		$	38,836
Net (Loss) Income(1)	$	(36,341	)	$	(13,945	)	$	13,189

As of December 31, 2019 and 2018, cumulative undistributed net earnings of all 50% or less owned companies included in the Company’s consolidated retained earnings were $16.1 million and $28.5 million, respectively.

MexMar. MexMar owns and operates 16 offshore support vessels in Mexico and manages 3 PSV’s and one FSV on behalf of OVH in Mexico. During the year ended December 31, 2019, there were no returns of capital advances or distributions to shareholders. During the year ended December 31, 2018, MexMar returned previously provided capital advances of $9.8 million. During the years ended December 31, 2019, 2018 and 2017 the Company charged $0.3 million of vessel management fees to MexMar.

SEACOSCO. On January 17, 2018, the Company announced the formation of SEACOSCO Offshore LLC (“SEACOSCO”), a Marshall Islands entity jointly owned by the Company and China Shipping Fan Tai Limited (“CSFT”) and China Shipping Industry (Hong Kong) Co., Limited (“CSIHK”) each affiliates of COSCO SHIPPING GROUP (“COSCO SHIPPING”). The Company, through SEACOR Offshore Asia LLC, a wholly-owned subsidiary of the Company (“SEACOR Offshore Asia”), owns an unconsolidated 50% interest in SEACOSCO, and CSFT and CSIHK own the other 50% interest in SEACOSCO. SEACOSCO entered into contracts for the purchase of eight Rolls-Royce designed, new construction platform supply vessels (“PSVs”) from COSCO SHIPPING HEAVY INDUSTRY (GUANGDONG) CO., LTD (the “Shipyard”), an affiliate of COSCO SHIPPING for approximately $163.3 million, of which 70% will be financed by the Shipyard, and secured by the PSVs on a non-recourse basis to the Company. SEACOSCO took delivery of two vessels in 2018, five vessels in 2019 and expects to take delivery of the final vessel in the first half of 2020. For the year ended December 31, 2019, and year ended December 31, 2018, the Company contributed capital to SEACOSCO of $2.0 million and $29.6 million, respectively. As the ship manager, the Company is responsible for full commercial, operational, and technical management of the vessels on a worldwide basis.

Effective May 31, 2019, SEACOR Offshore Asia, CSFT, CSIHK and the Shipyard, the shipbuilder and lender under deferred payment agreements (“DPAs”) that are secured by the PSVs acquired by SEACOSCO, entered into a Memorandum of Understanding (“MOU”) pursuant to which (i) the Shipyard agreed to not take any action with respect to any existing defaults under the DPAs until August 31, 2019, (ii) SEACOR Offshore Asia was authorized to provide, in its sole discretion, shareholder loans to SEACOSCO and/or its subsidiaries, in an aggregate amount of $13.0 million, in respect of working capital or other payment obligations at an interest rate of 15% per annum and, subject to the priority of the indebtedness under the DPAs, the shareholder loans will have senior priority to any and all other debts of SEACOSCO and/or its subsidiaries, (“SEACOR Shareholder Loans”), (iii) the parties set out the non-binding principal terms and conditions for SEACOR Offshore Asia’s potential acquisition of the 50% interest in SEACOSCO owned by CSFT and CSIHK and (iv) in connection with such acquisition, SEACOR Offshore Asia or its nominee may acquire from the Shipyard two additional PSVs that had been under options held by SEACOSCO. As of December 31, 2019, the balance on the SEACOR Shareholder Loans is $13.0 million, which is the aggregate amount of Shareholder Loans provided, plus capitalized interest of $0.6 million. The Company, as ship manager, has also advanced $2.1 million to SEACOSCO in respect of receivables. As of December 31, 2019, SEACOSCO is in compliance with all debt covenants and is current in all payments. Management remains in discussions with the Shipyard, CSFT and CSIHK with respect to the other transactions contemplated by the MOU.

OSV Partners. SEACOR OSV Partners GP LLC and SEACOR OSV Partners I LP (collectively “OSV Partners”) own and operate five offshore support vessels. On September 28, 2018, OSV Partners amended its term loan facility to, among other things, extend its maturity to September 28, 2021, and in connection therewith, the Company participated in a $5.0 million preferred equity offering by OSV Partners and subordinated loan in the amount of $5.0 million issued by OSV Partners, investing $1.1 million in such preferred equity (and committing to invest an additional $1.1 million in such preferred equity if called by the general partner of OSV Partners prior to September 30, 2020) and providing $2.1 million of such loan. On December 18, 2019, the general partner of OSV Partners called the remaining commitments of the Company and other limited partners and the Company satisfied its commitment with an additional $1.1 million investment in such preferred equity. The Company has no further commitments to OSV Partners. On December 23, 2019, OSV Partners further amended its term loan facility to, among other things, provide for interest-only payments during 2020 with the next principal payment due March 31, 2021. The lenders to OSV Partners have no recourse to the Company for outstanding amounts under the facility, and the Company is not obligated to participate in any future investment in or loan any money to OSV Partners. During the year ended December 31, 2017, the Company participated in a $6.0 million preferred equity offering of OSV Partners and invested $2.3 million in support of the venture. For the year ended December 31, 2019, vessel management fees were abated and not charged. For the years ended December 31, 2018 and 2017, the Company received $0.6 million, of vessel management fees from OSV Partners for each year.

SEACOR Marlin. SEACOR Marlin LLC (“SMLLC”) own and operate Seacor Marlin supply vessel. On September 13, 2018, the Company sold 51% of SMLLC to MOMI, a wholly-owned subsidiary of MexMar, for $8.0 million in cash, which generated a gain of $0.4 million. The Seacor Marlin supply vessel was pledged as collateral under the MexMar credit facility, for which the Company receives an annual collateral fee.

MEXMAR Offshore. On December 20, 2018, UP Offshore (Bahamas) Ltds (“UP Offshore”), a provider of offshore support vessel services to the energy industry in Brazil, was acquired by MEXMAR Offshore, a new joint venture company that is 49% owned by the Company, and 51% owned by a subsidiary of CME. MEXMAR Offshore acquired UP Offshore for nominal consideration, re-financed its existing debt to fund capital expenditures on two vessels and a $10.0 million loan to fund new working capital requirements. As of December 31, 2019, UP Offshore’s 13 vessel fleet, 10 vessels were located and registered in Brazil and two were located and registered in Mexico. During the year ended December 31, 2019, UP Offshore sold one PSV to a third party and repositioned three PSV’s to Mexico.

Offshore Vessel Holdings. On December 28, 2018, the Company invested $4.9 million for a 49% interest in Offshore Vessel Holdings SAPI de CV (“OVH”), the remaining 51% is owned by a subsidiary of CME. OVH invests in offshore assets and charters marine equipment. During the year ended December 31, 2019 OVH loaned $10.0 million to Operadora Productura Mexsicana, a drilling company in Mexico which owns and operates two jackup drilling rigs (“OPM”), chartered in three PSV’s from UP Offshore and purchased one FSV from the Company for $2.4 million through a seller’s finance agreement.

Dynamic Offshore Drilling. Dynamic Offshore Drilling Ltd. (“Dynamic Offshore Drilling”) was established to construct and operate a jack-up drilling rig that was delivered in the first quarter of 2013. During the year ended December 31, 2017, the Company recognized an impairment charge of $8.3 million, net of tax, for an-other-than-temporary decline in the fair value of its equity investment upon Dynamic Offshore Drilling’s unsuccessful bid on a charter renewal with a customer. During the year ended December 31, 2018, the Company recognized equity losses in Dynamic Offshore Drilling of $2.0 million. During 2019, the Company recorded additional losses of $2.3 million which lowered the investment value to zero.

Nautical Power. During the quarter ended September 30, 2018, the joint venture repaid the Company’s $6.4 million investment in Nautical Power, LLC (“Nautical Power”) in cash.

Falcon Global. Falcon Global was formed to construct and operate two foreign-flag liftboats. During the three months ended March 31, 2017, the Company and its partner each contributed additional capital of $0.4 million, and the Company made working capital advances of $2.0 million to Falcon Global. In March 2017, the Company’s partner declined to participate in a capital call from Falcon Global and, as a consequence, the Company obtained 100% voting control of Falcon Global in accordance with the terms of the operating agreement. On February 8, 2018, 100% of the equity interests of Falcon Global were contributed to FGH and its designated subsidiaries as part of the formation of the FGH joint venture.

Sea-Cat Crewzer II. Sea-Cat Crewzer II owns and operates two high-speed offshore catamarans. On April 28, 2017, the Company acquired a 100% controlling interest in Sea-Cat Crewzer II through the acquisition of its partners’ 50% ownership interest for $11.3 million in cash.

Sea-Cat Crewzer. Sea-Cat Crewzer owns and operates two high-speed offshore catamarans. On April 28, 2017, the Company acquired a 100% controlling interest in Sea-Cat Crewzer through the acquisition of its partners’ 50% ownership interest for $4.4 million in cash.

Other. The Company’s other 50% or less owned companies own and operate five vessels. During the year ended December 31, 2019, the Company received dividends of $2.1 million and $0.5 million of return capital from these 50% or less owned companies. During the year ended December 31, 2018, the Company recognized impairment charges of $1.2 million, net of tax, to reduce its investment carrying value in a certain 50% or less owned company to zero. During the year ended December 31, 2017, the Company received dividends of $2.6 million, made capital contributions and advances of $0.8 million and received repayments on advances of $0.2 million with these 50% or less owned companies. In addition, during the year ended December 31, 2017, the Company recognized impairment charges of $0.5 million, net of tax, for an other-than-temporary decline in the fair value of its investment in a certain 50% or less owned company. During the years ended December 31, 2019, the Company received less than $0.1 million of vessel management fees from these 50% or less owned companies. In the years ended December 31, 2018 and 2017, the Company received $0.3 million, and $0.7 million, respectively.

Leases - Additional Information (Details) $ in Thousands		12 Months Ended
Leases - Additional Information (Details) $ in Thousands	Jan. 01, 2019 USD ($)	Dec. 31, 2019 USD ($) Vessel	Dec. 31, 2018 USD ($)
Lessee Lease Description [Line Items]
Operating Lease, Right-of-Use Asset		$ 17,313
Operating Lease, Liability		24,921
Operating Lease, Impairment Loss		$ 5,300	$ 6,800
Number of Operating Leases Impaired		1	3
Anchor Handling Towing Supply
Lessee Lease Description [Line Items]
Number of operating leases on equipment \| Vessel		3
Liftboats
Lessee Lease Description [Line Items]
Number of operating leases on equipment \| Vessel		2
Fast Support Vessels
Lessee Lease Description [Line Items]
Number of operating leases on equipment \| Vessel		1
Vessels \| Minimum
Lessee Lease Description [Line Items]
Operating lease, lease terms (in duration)		11 years
Vessels \| Maximum
Lessee Lease Description [Line Items]
Operating lease, lease terms (in duration)		23 months
Other Equipment \| Minimum
Lessee Lease Description [Line Items]
Operating lease, lease terms (in duration)		1 month
Other Equipment \| Maximum
Lessee Lease Description [Line Items]
Operating lease, lease terms (in duration)		324 months
Accounting Standards Update 2016-02
Lessee Lease Description [Line Items]
Operating Lease, Right-of-Use Asset	$ 33,700
Operating Lease, Liability	31,900
Accounting Standards Update 2016-02 \| Change in Accounting Principle for Equipment, Office and Land Leases
Lessee Lease Description [Line Items]
Cumulative Effect on Retained Earnings, Net of Tax, Total	1,700
Accounting Standards Update 2016-02 \| Change in Accounting Principle for Unamortized Deferred Gains
Lessee Lease Description [Line Items]
Cumulative Effect on Retained Earnings, Net of Tax, Total	8,700
Cumulative effect on retained earnings, Before tax	11,000
Cumulative effect on retained earnings, Tax	$ 2,300

Share Based Compensation - Schedule of Stock Option Transactions (Details) (Parenthetical)	12 Months Ended
	Dec. 31, 2019
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Share-based compensation arrangement by share-based payment award, options, exercisable, weighted average remaining contractual term	8 years 2 months 23 days

Schedule II - Valuation and Qualifying Accounts (Tables)

12 Months Ended

Dec. 31, 2019

Valuation And Qualifying Accounts [Abstract]

Schedule of Valuation and Qualifying Accounts

Description	Balance Beginning of Year		Charges (Recoveries) to Cost and Expenses			Deductions⁽¹⁾			Balance End of Year
Year Ended December 31, 2019
Allowance for doubtful accounts (deducted from trade and notes receivable)	$	860	$	(405	)	$	—		$	455
Year Ended December 31, 2018
Allowance for doubtful accounts (deducted from trade and notes receivable)	$	4,039	$	(928	)	$	(2,251	)	$	860
Year Ended December 31, 2017
Allowance for doubtful accounts (deducted from trade and notes receivable)	$	5,359	$	(1,283	)	$	(37	)	$	4,039

(1)	Trade receivable amounts deemed uncollectible that were removed from accounts receivable and allowance for doubtful accounts.

Investments, at Equity, and Advances to 50% or Less Owned Companies (Tables)

12 Months Ended

Dec. 31, 2019

Schedule Of Investments [Abstract]

Equity Method Investments

Investments, at equity, and advances to 50% or less owned companies as of December 31 were as follows (in thousands):

	Ownership			2019		2018
MexMar		49.0	%	$	54,249	$	53,840
SEACOSCO		50.0	%		23,926		28,002
OSV Partners		30.4	%		10,669		11,087
SEACOR Marlin		49.0	%		7,929		7,579
MEXMAR Offshore⁽¹⁾		49.0	%		—		4,900
Offshore Vessel Holdings		49.0	%		4,052		4,900
Dynamic Offshore Drilling		19.0	%		—		2,263
Nautical Power		50.0	%		—		—
Other	20.0% — 50.0%				4,396		9,202
				$	105,221	$	121,773

(1)

^{This joint venture holds the investment in UP}^Offshore

	2019		2018
Current assets	$	108,238	$	99,400
Noncurrent assets		618,745		567,628
Current liabilities		106,742		59,912
Noncurrent liabilities		338,836		325,700

	2019			2018			2017
Operating Revenues	$	142,327		$	109,636		$	147,360
Costs and Expenses:
Operating and administrative		119,767			77,952			78,025
Depreciation		28,800			26,443			30,499
		148,567			104,395			108,524
Loss on Asset Dispositions and Impairments, Net		(166	)		(89	)		—
Operating Income	$	(6,406	)	$	5,152		$	38,836
Net (Loss) Income(1)	$	(36,341	)	$	(13,945	)	$	13,189

Noncontrolling Interests in Subsidiaries - Additional Information (Details) - USD ($) $ in Thousands		3 Months Ended								12 Months Ended
	Feb. 08, 2018	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Mar. 15, 2019	Jan. 25, 2019
Minority Interest [Line Items]
Net income (loss), including portion attributable to noncontrolling interest, total		$ (21,918)	$ (18,240)	$ (30,264)	$ (28,273)	$ (7,969)	$ (15,766)	$ (26,629)	$ (31,688)	$ (98,695)	$ (82,052)	$ (38,540)
Net income (loss) attributable to noncontrolling interest, total										(5,858)	$ (4,444)	$ (5,639)
Falcon Global Holdings
Minority Interest [Line Items]
Joint venture total capital	$ 112,500
Joint venture contribution from previous joint venture	43,300
Joint venture contribution from noncontrolling interest	$ 18,800
Falcon Global Holdings
Minority Interest [Line Items]
Noncontrolling interest, ownership percentage by parent	72.00%
Net income (loss), including portion attributable to noncontrolling interest, total										21,000
Net income (loss) attributable to noncontrolling interest, total										5,900
Net assets, ending balance		$ 77,200								$ 77,200
Windcat Workboats
Minority Interest [Line Items]
Noncontrolling interest, ownership percentage by parent						12.50%					12.50%
Net income (loss), including portion attributable to noncontrolling interest, total											$ (3,100)
Net income (loss) attributable to noncontrolling interest, total											(400)
Net assets, ending balance						$ 16,900					$ 16,900
Windcat Workboats \| Seabulk Overseas
Minority Interest [Line Items]
Noncontrolling interest, ownership percentage by parent														87.00%
Business acquisition, percentage of voting interests acquired													6.25%	6.25%

Nature of Operations and Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2019

Accounting Policies [Abstract]

Nature of Operations and Segmentation

Nature of Operations and Segmentation. The consolidated financial statements include the accounts of SEACOR Marine and its consolidated subsidiaries (collectively referred to as the “Company”). The Company provides global marine and support transportation services to offshore oil, natural gas and windfarm facilities worldwide. The Company and its joint ventures operate a diverse fleet of offshore support and specialty vessels that (i) deliver cargo and personnel to offshore installations, (ii) handle anchors and mooring equipment required to tether rigs to the seabed, (iii) tow rigs and assist in placing them on location and moving them between regions, (iv) provide construction, well work-over and decommissioning support and (v) carry and launch equipment used underwater in drilling and well installation, maintenance, inspection and repair. Additionally, the Company’s vessels provide accommodations for technicians and specialists, safety support and emergency response services. The Company’s fleet also features crew transfer vessels (“CTVs”) used primarily in windfarm operations.

Accounting standards require public business enterprises to report information about each of their operating business segments that exceed certain quantitative thresholds or meet certain other reporting requirements. Operating business segments have been defined as a component of an enterprise about which separate financial information is available and is evaluated regularly by the chief operating decision maker in assessing performance. On December 2, 2019, the Company completed the sale of its North Sea standby safety business. Unless the context indicates otherwise, the footnotes to these financial statements reflect continuing operations after the disposition. The Company has identified the following five principal geographic regions as its reporting segments:

United States, primarily Gulf of Mexico. The Company’s vessels in this market support deepwater anchor handling, fast cargo transport, general cargo transport, well intervention, work-over, decommissioning, and diving support operations.

Africa, primarily West Africa. The Company’s vessels in this area generally support projects for major oil companies, primarily in Angola and Nigeria.

Middle East and Asia. The Company’s vessels in this area generally support exploration, personnel transport and seasonal construction activities in Egypt, Israel, Malaysia and countries along the Arabian Gulf and Arabian Sea, such as Saudi Arabia, the United Arab Emirates and Qatar.

Latin America. As of December 31, 2019, 34 vessels were located in this region, including four owned and 30 joint-ventured. Of these joint-ventured vessels, (i) 16 are owned by Mantenimiento Express Maritimo, S.A.P.I. de C.V. (“MexMar”), a joint venture company that is 49% owned by SEACOR Marine International LLC (“SMI”), a wholly owned subsidiary of SEACOR Marine, and 51% owned by subsidiaries of Proyectos Globales de Energía y Servicios CME, S.A. de C.V. (“CME”), (ii) 13 of such vessels are owned by MEXMAR Offshore International LLC (“MEXMAR Offshore”), a joint venture company that is 49% owned by SMI and 51% owned by a subsidiary of CME and (iii) one is owned by SEACOSCO. These vessels, consisting of a fleet of FSVs, supply, specialty and liftboat vessels, provide support for exploration and production activities in Mexico, Brazil and Guyana. From time to time, the Company’s vessels also work in Trinidad and Tobago, and Colombia.

Europe, primarily North Sea. As of December 31, 2019, 43 vessels were located in this region supporting the construction and maintenance of offshore wind turbines, including 37 owned and six joint ventured. On December 2, 2019, the Company completed the sale of its North Sea standby safety business, comprised of 18 emergency response and rescue vessels (“ERRVs”) related vessels located in the North Sea providing standby safety and supply services.

The Spin-off. SEACOR Marine was previously a subsidiary of SEACOR Holdings Inc. (along with its consolidated subsidiaries, other than SEACOR Marine, collectively referred to as “SEACOR Holdings”). On June 1, 2017, SEACOR Holdings completed a spin-off of SEACOR Marine by way of a pro rata dividend of SEACOR Marine’s Common Stock, all of which was then held by SEACOR Holdings, to SEACOR Holdings’ shareholders of record as of May 22, 2017 (the “Spin-off”). SEACOR Marine entered into certain agreements with SEACOR Holdings to govern SEACOR Marine’s relationship with SEACOR Holdings following the Spin-off, including a Distribution Agreement, two Transition Services Agreements, an Employee Matters Agreement and a Tax Matters Agreement. Immediately following the Spin-off, SEACOR Marine began to operate as an independent, publicly traded company.

Basis of Consolidation

Basis of Consolidation. The consolidated financial statements include the accounts of SEACOR Marine and its controlled subsidiaries. Control is generally deemed to exist if the Company has greater than 50% of the voting rights of a subsidiary. All significant intercompany accounts and transactions are eliminated in the combination and consolidation.

Noncontrolling interests in consolidated subsidiaries are included in the consolidated balance sheets as a separate component of equity. The Company reports consolidated net income (loss) inclusive of both the Company’s and the noncontrolling interests' share, as well as the amounts of consolidated net income (loss) attributable to each of the Company and the noncontrolling interests. If a subsidiary is deconsolidated upon a change in control, any retained noncontrolled equity investment in the former controlled subsidiary is measured at fair value and a gain or loss is recognized in net income (loss) based on such fair value. If a subsidiary is consolidated upon a change in control, any previous noncontrolled equity investment in the subsidiary is measured at fair value and a gain or loss is recognized in net income (loss) based on such fair value.

The Company employs the equity method of accounting for investments in 50% or less owned companies that it does not control but has the ability to exercise significant influence over the operating and financial policies of the business venture. Significant influence is generally deemed to exist if the Company has between 20% and 50% of the voting rights of a business venture, but may exist when the Company’s ownership percentage is less than 20%. In certain circumstances, the Company may have an economic interest in excess of 50% but may not control and consolidate the business venture. Conversely, the Company may have an economic interest less than 50% but may control and consolidate the business venture. The Company reports its investments in and advances to these business ventures in the accompanying consolidated balance sheets as investments, at equity, and advances to 50% or less owned companies. The Company reports its share of earnings from investments in 50% or less owned companies in the accompanying consolidated statements of loss as equity in earnings (losses) of 50% or less owned companies, net of tax.

The Company employs the cost method of accounting for investments in 50% or less owned companies it does not control or exercise significant influence. These investments in private companies are carried at cost and are adjusted only for capital distributions and other-than-temporary declines in fair value.

Certain reclassifications were made to previously reported amounts in the consolidated financial statements and notes thereto to make them consistent with the current period presentation.

Use of Estimates

Use of Estimates. The preparation of financial statements in conformity with accounting principles generally accepted in the U.S. requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Such estimates include those related to deferred revenues, allowance for doubtful accounts, useful lives of property and equipment, impairments, income tax provisions and certain accrued liabilities. Actual results could differ from estimates and those differences may be material.

Revenue Recognition

Revenue Recognition. The Company contracts with various customers to carry out management services for vessels as agents for and on behalf of ship owners. These services include crew management, technical management, commercial management, insurance arrangements, sale and purchase of vessels, provisions and bunkering. As the manager of the vessels, the Company undertakes to use its best endeavors to provide the agreed management services as agents for and on behalf of the owners in accordance with sound ship management practice and to protect and promote the interest of the owners in all matters relating to the provision of services hereunder. The Company also contracts with various customers to carry out management services regarding engineering for vessel construction and vessel conversions. The vast majority of the ship management agreements span over the length of one to three years and are typically billed on a monthly basis. The Company transfers control of the service to the customer and satisfies its performance obligation over the term of the contract, and therefore recognized revenue over the term of the contract while related costs are expensed as incurred.

	2019			2018			2017
Balance at beginning of year	$	1,327		$	10,104		$	6,953
Revenues deferred during the year		8,164			3,600			4,699
Revenues recognized during the year		(4,705	)		(12,377	)		(1,548	)
Balance at end of year	$	4,786		$	1,327		$	10,104

As of December 31, 2019, the Company deferred revenues of $4.8 million primarily related to $2.0 million of prepaid vessel management fees, and $1.8 million related to the time charter of offshore support vessels to customers from which collections were not reasonably assured.

The Company earns revenue primarily from the time charter and bareboat charter of vessels to customers. Since the Company charges customers based upon daily rates of hire, vessel revenues are recognized on a daily basis throughout the contract period. Under a time charter, the Company provides a vessel to a customer and is responsible for all operating expenses, typically excluding fuel. Under a bareboat charter, the Company provides a vessel to a customer and the customer assumes responsibility for all operating expenses and assumes all risks of operation. In the U.S. Gulf of Mexico, time charter durations and rates are typically established in the context of master service agreements that govern the terms and conditions of the charter. From time to time, the Company may also participate in pooling arrangements. In a pooling arrangement, the time charter revenues of certain of the Company’s vessels are shared with the time charter revenues of certain vessels of similar type owned by non-affiliated vessel owners based upon an agreed formula. On January 9, 2019, the only active pooling arrangement was terminated, and three FSV’s were purchased by the Company.

Contract or charter durations may range from several days to several years. Charters vary in length from short-term to multi-year periods, many with cancellation clauses and without early termination penalties. As a result of options and frequent renewals, the stated duration of charters may have little correlation with the length of time the vessel is contracted to provide services to a particular customer.

Cash Equivalents

Cash Equivalents. The Company considers all highly liquid investments with an original maturity of three months or less, when purchased, to be cash equivalents. Cash equivalents consist of U.S. treasury securities, money market instruments, time deposits and overnight investments.

Restricted Cash

Restricted Cash. Restricted cash primarily relates to banking facility requirements.

For the year ended December 31, cash, cash equivalents and restricted cash consists of:

	2019		2018
Cash	$	83,943	$	91,597
Cash equivalents		—		—
Restricted cash		3,104		1,657
Total	$	87,047	$	93,254

Marketable Securities

Marketable Securities. Marketable equity securities with readily determinable fair values and debt securities are reported in the accompanying consolidated balance sheets as marketable securities. These investments are stated at fair value, as determined by their market observable prices, with both realized and unrealized gains and losses reported in the accompanying consolidated statements of loss as marketable security losses, net. Short sales of marketable securities are stated at fair value in the accompanying consolidated balance sheets with both realized and unrealized losses reported in the accompanying consolidated statements of loss as marketable security gains (losses), net. Marketable securities are classified as trading securities for financial reporting purposes with gains and losses reported as operating activities in the accompanying consolidated statements of cash flows.

Trade and Other Receivables

Trade and Other Receivables. Customers are primarily major integrated national and international oil companies, large independent oil and natural gas exploration and production companies, and offshore windfarm operations. Customers are granted credit on a short-term basis and the related credit risks are minimal. Other receivables consist primarily of operating expenses the Company incurs in relation to vessels it manages for other entities, as well as insurance and income tax receivables. The Company routinely reviews its receivables and makes provisions for probable doubtful accounts; however, those provisions are estimates and actual results may materially differ from those estimates. Trade receivables are deemed uncollectible and are removed from accounts receivable and the allowance for doubtful accounts when collection efforts have been exhausted.

Derivative Instruments

Derivative Instruments. The Company accounts for derivatives through the use of a fair value concept whereby all of the Company’s derivative positions are stated at fair value in the accompanying consolidated balance sheets. Realized and unrealized gains and losses on derivatives not designated as hedges are reported in the accompanying consolidated statements of loss as Derivative gains (losses), net. Realized and unrealized gains and losses on derivatives designated as fair value hedges are recognized as corresponding increases or decreases in the fair value of the underlying hedged item to the extent they are effective, with any ineffective portion reported in the accompanying consolidated statements of loss as Derivative gains (losses), net. Realized and unrealized gains and losses on derivatives designated as cash flow hedges are reported as a component of other comprehensive loss in the accompanying consolidated statements of comprehensive loss to the extent they are effective and reclassified into earnings on the same line item associated with the hedged transaction and in the same period the hedged transaction affects earnings. Any ineffective portions of cash flow hedges are reported in the accompanying consolidated statements of loss as Derivative gains (losses), net. Realized and unrealized gains and losses on derivatives designated as cash flow hedges that are entered into by the Company’s 50% or less owned companies are also reported as a component of the Company’s other comprehensive loss in proportion to the Company’s ownership percentage, with reclassifications and ineffective portions being included in Equity in earnings (losses) of 50% or less owned companies, net of tax, in the accompanying consolidated statements of loss.

Concentrations of Credit Risk

Concentrations of Credit Risk. The Company is exposed to concentrations of credit risk associated with its cash and cash equivalents, restricted cash, construction reserve funds and derivative instruments. The Company minimizes its credit risk relating to these positions by monitoring the financial condition of the financial institutions and counterparties involved and by primarily conducting business with large, well-established financial institutions and diversifying its counterparties. The Company does not currently anticipate nonperformance by any of its significant counterparties. The Company is also exposed to concentrations of credit risk relating to its receivables due from customers described above. The Company does not generally require collateral or other security to support its outstanding receivables. The Company minimizes its credit risk relating to receivables by performing ongoing credit evaluations and, to date, credit losses have not been material.

Inventories

Inventories. Inventories, which consist of fuel and supplies, are stated at the lower of cost (using the first-in, first-out method) or market. The Company records write-downs, as needed, to adjust the carrying amount of inventories to the lower of cost or market. In the year ended December 31, 2019, 2018 and 2017, there were no inventory reserves.

Property and Equipment

Property and Equipment. Equipment, stated at cost, is depreciated using the straight-line method over the estimated useful life of the asset to an estimated salvage value. With respect to offshore support vessels, the estimated useful life is typically based upon a newly built vessel being placed into service and represents the point at which it is typically not justifiable for the Company to continue to operate the vessel in the same or similar manner. From time to time, the Company may acquire older vessels that have already exceeded the Company’s useful life policy, in which case the Company depreciates such vessels based on its best estimate of remaining useful life, typically the next regulatory survey or certification date.

As of December 31, 2019, the estimated useful life (in years) of each of the Company’s major categories of new offshore support vessels was as follows:

Offshore Support Vessels:
Crew transfer vessels		10
All other offshore support vessels (excluding crew transfer)		20

The Company’s property and equipment as of December 31 was as follows (in thousands):

	Historical Cost ⁽¹⁾		Accumulated Depreciation			Net Book Value
2019
Offshore support vessels:
AHTS⁽²⁾	$	94,078	$	(73,095	)	$	20,983
FSV⁽³⁾		388,460		(101,295	)		287,165
Supply		44,958		(8,471	)		36,487
Specialty		14,805		(10,466	)		4,339
Liftboats		327,028		(93,166	)		233,862
Crew transfer		82,645		(54,358	)		28,287
General machinery and spares		7,650		(7,648	)		2
Other ⁽⁴⁾		17,354		(10,463	)		6,891
	$	976,978	$	(358,962	)	$	618,016
2018
Offshore support vessels:
AHTS⁽²⁾	$	197,344	$	(168,731	)	$	28,613
FSV⁽³⁾		404,310		(98,580	)		305,730
Supply		64,284		(37,202	)		27,082
Specialty		25,683		(20,433	)		5,250
Liftboats		329,473		(71,887	)		257,586
Crew transfer		73,589		(46,614	)		26,975
General machinery and spares		8,457		(8,390	)		67
Other ⁽⁴⁾		13,443		(9,562	)		3,881
	$	1,116,583	$	(461,399	)	$	655,184

(1)	Includes property and equipment acquired in business acquisitions at acquisition date fair value, and net of the impact of recognized impairment charges.

(2)	Anchor Handling Towing Supply (“AHTS”)

(3)	Fast support vessels (“FSVs”).

(4)	Includes land, buildings, leasehold improvements, vehicles and other property and equipment.

Depreciation and amortization expense from continuing operations totaled $64.0 million, $68.8 million and $60.3 million in 2019, 2018 and 2017, respectively.

On December 2, 2019, the Company completed the sale of its North Sea standby business, comprised of 18 ERRVs with a net book value of $24.3 million. Depreciation and amortization expense totaled $3.5 million, $3.4 million and $2.5 million in 2019, 2018 and 2017, respectively.

Equipment maintenance and repair costs and the costs of routine overhauls, drydockings and inspections performed on vessels and equipment are charged to operating expense as incurred. Expenditures that extend the useful life or improve the marketing and commercial characteristics of vessels, as well as major renewals and improvements to other properties, are capitalized.

Certain interest costs incurred during the construction of vessels are capitalized as part of the vessels’ carrying values and are amortized over such vessels’ estimated useful lives. Capitalized interest totaled $1.5 million, $2.4 million and $3.6 million in 2019, 2018 and 2017, respectively.

Impairment of Long-Lived Assets and Impairment of 50% or Less Owned Companies

Impairment of Long-Lived Assets. The Company performs an impairment analysis of long-lived assets used in operations, including intangible assets, when indicators of impairment are present. These indicators may include a significant decrease in the market price of a long-lived asset or asset group, a significant adverse change in the extent or manner in which a long-lived asset or asset group is being used or in its physical condition, or a current period operating or cash flow loss combined with a history of operating or cash flow losses or a forecast that demonstrates continuing losses associated with the use of a long-lived asset or asset group. If the carrying values of the assets are not recoverable, as determined by their estimated future undiscounted cash flows, the estimated fair value of the assets or asset groups are compared to their current carrying values and impairment charges are recorded if the carrying value exceeds fair value.

As a result of the difficult conditions experienced in the offshore oil and natural gas markets beginning in the second half of 2014 and the corresponding reductions in utilization and rates per day worked of its fleet, the Company identified indicators of impairment and recognized impairment charges primarily associated with its AHTS fleet, its liftboat fleet, certain specialty vessels, vessels removed from service and goodwill. When reviewing its fleet for impairment, the Company groups vessels with similar operating and marketing characteristics, including cold-stacked vessels expected to return to active service, into vessel classes. All other vessels, including vessels retired and removed from service, are evaluated for impairment on a vessel by vessel basis.

During the year ended December 31, 2019, the Company recorded non-cash impairment charges of $12.0 million primarily related to four anchor-handling towing supply (“AHTS”) vessels previously removed from service and adjusted to scrap value, and four fast support vessels (“FSV”) each of which has been adjusted to indicative sales price, and two leased-in vessels (one AHTS and one platform supply vessel “PSV”), adjusted for indicative future cash flows. During the year ended December 31, 2018, the Company recorded non-cash impairment charges of $14.6 million primarily associated with its AHTS fleet (four owned vessels and three leased-in vessels) and one specialty vessel. During the year ended December 31, 2017, the Company recorded non-cash impairment charges of $27.5 million primarily associated with its AHTS vessels, one leased-in supply vessel removed from service as it is not expected to be marketed prior to the expiration of its lease, one owned FSV removed from service and two owned in-service specialty vessels. Estimated fair values for the Company’s owned vessels were established by independent appraisers and other market data such as recent sales of similar vessels (see Note 11). If market conditions further decline from the depressed utilization and rates per day worked experience over the last three years, fair values based on future appraisals could decline significantly.

The Company’s other vessel classes and other individual vessels in active service and cold-stacked status, for which no impairment was deemed necessary, have generally experienced a less severe decline in utilization and rates per day worked based on specific market factors. The market factors include vessels with more general utility to a broad range of customers (e.g., FSVs), vessels required for customers to meet regulatory mandates and operating under multiple year contracts or vessels that service customers outside of the offshore oil and natural gas market (e.g., CTVs).

For vessel classes and individual vessels with indicators of impairment but not recently impaired as of December 31, 2019, the Company has estimated that their future undiscounted cash flows exceed their current carrying values. The Company’s estimates of future undiscounted cash flows are highly subjective as utilization and rates per day worked are uncertain, including the timing of an estimated market recovery in the offshore oil and natural gas markets and the timing and cost of reactivating cold-stacked vessels. If market conditions decline further, changes in the Company’s expectations on future cash flows may result in recognizing additional impairment charges related to its long-lived assets in future periods.

Impairment of 50% or Less Owned Companies. Investments in 50% or less owned companies are reviewed periodically to assess whether there is an other-than-temporary decline in the carrying value of the investment. In its evaluation, the Company considers, among other items, recent and expected financial performance and returns, impairments recorded by the investee and the capital structure of the investee. When the Company determines the estimated fair value of an investment is below carrying value and the decline is other-than-temporary, the investment is written down to its estimated fair value. Actual results may vary from the Company’s estimates due to the uncertainty regarding projected financial performance, the severity and expected duration of declines in value, and the available liquidity in the capital markets to support the continuing operations of the investee, among other factors. Although the Company believes its assumptions and estimates are reasonable, the investee’s actual performance compared with the estimates could produce different results and lead to additional impairment charges in future periods. No impairment charges of investments in 50% or less owned companies were incurred for the year ended December 31, 2019. During the years ended 2018 and 2017, the Company recognized impairment charges of $1.2 million and $8.8 million, respectively, net of tax, related to its 50% or less owned companies (see Note 5).

Business Combinations

Business Combinations. The Company recognizes 100% of the fair value of assets acquired, liabilities assumed, and noncontrolling interests when the acquisition constitutes a change in control of the acquired entity. Shares issued in consideration for a business combination, contingent consideration arrangements and pre-acquisition loss and gain contingencies are all measured and recorded at their acquisition-date fair value. Subsequent changes to fair value of contingent consideration arrangements are generally reflected in earnings. Acquisition-related transaction costs are expensed as incurred and any changes in an acquirer’s existing income tax valuation allowances and tax uncertainty accruals are recorded as an adjustment to income tax expense. The operating results of entities acquired are included in the accompanying consolidated statements of loss from the date of acquisition (see Note 3).

Debt Discount and Issue Costs

Debt Discount and Issue Costs. Debt discounts and costs incurred in connection with the issuance of debt are amortized over the life of the related debt using the effective interest rate method for term loans and straight-line method for revolving credit facilities and are included in interest expense in the accompanying consolidated statements of loss.

Self-insurance Liabilities

Self-insurance Liabilities. The Company maintains marine hull, liability and war risk, general liability, workers compensation and other insurance customary in the industry in which it operates. Both the marine hull and liability policies have annual aggregate deductibles. Marine hull annual aggregate deductibles are accrued as claims are incurred while marine liability annual aggregate deductibles are accrued based on historical loss experience. Exposure to the health benefit plans are limited by maintaining stop-loss and aggregate liability coverage. To the extent that estimated self-insurance losses, including the accrual of annual aggregate deductibles, differ from actual losses realized, the Company’s insurance reserves could differ significantly and may result in either higher or lower insurance expense in future periods.

Income Taxes

Income Taxes. Deferred income tax assets and liabilities have been provided in recognition of the income tax effect attributable to the book and tax basis differences of assets and liabilities reported in the accompanying consolidated financial statements. Deferred tax assets or liabilities are provided using the enacted tax rates expected to apply to taxable income in the periods in which they are expected to be settled or realized. Interest and penalties relating to uncertain tax positions are recognized in interest expense and administrative and general, respectively, in the accompanying consolidated statements of loss. The Company records a valuation allowance to reduce its deferred tax assets if it is more likely than not that some portion or all of the deferred tax assets will not be realized.

The Global Intangible Low Taxed Income (“GILTI”) regime effectively imposes a minimum tax on worldwide foreign earnings and subjects U.S. shareholders of controlled foreign corporations (“CFCs”) to current taxation on certain income earned through a CFC. The Company has made the policy election to record any liability, associated with GILTI in the period in which it is incurred.

Prior to the Spin-off, SEACOR Marine was included in the consolidated U.S. federal income tax return of SEACOR Holdings. SEACOR Holdings’ policy for allocation of U.S. federal income taxes required its domestic subsidiaries included in the consolidated U.S. federal income tax return to compute their provision for U.S. federal income taxes on a separate company basis and settle with SEACOR Holdings.

In the normal course of business, the Company or SEACOR Holdings may be subject to challenges from tax authorities regarding the amount of taxes due for the Company. These challenges may alter the timing or amount of taxable income or deductions. As part of the calculation of income tax expense, the Company determines whether the benefits of its tax positions are at least more likely than not of being sustained based on the technical merits of the tax position. For tax positions that are more likely than not of being sustained, the Company accrues the largest amount of the tax benefit that is more likely than not of being sustained. Such accruals require management to make estimates and judgments with respect to the ultimate outcome of its tax benefits and actual results could vary materially from these estimates.

Deferred Gains - Vessel Sale-Leaseback Transactions and Financed Vessel Sales

Deferred Gains - Vessel Sale-Leaseback Transactions and Financed Vessel Sales. Prior to the implementation of ASC 842, the Company entered into vessel sale-leaseback transactions with finance companies or provided seller financing on sales of its vessels to third-parties or to 50% or less owned companies. A portion of the gains realized from these transactions was not immediately recognized in income but rather was recorded in the accompanying consolidated balance sheets in deferred gains and other liabilities. In sale-leaseback transactions, gains were deferred to the extent of the present value of future minimum lease payments and were amortized as reductions to rental expense over the applicable lease terms (see Note 7). When the Company determines that future cash inflows do not support future lease cash obligations, the Company records an impairment expense for the amount of the cash flow shortage of all future lease costs, costs to maintain the vessel to the end of the lease term, and costs to return the vessel to its owner, less the amount of any unamortized deferred gains. In financed vessel sales, gains were deferred to the extent that the repayment of purchase notes were dependent on the future operations of the sold vessels and were amortized based on cash received from the buyers. Unamortized deferred gains for four vessels under sale-leaseback agreements were fully recognized as an adjustment to Retained Earnings with the implementation of the new leasing standard (see Note 7). Deferred gain activity related to these transactions for the years ended December 31 was as follows (in thousands):

	2019			2018			2017
Balance at beginning of year	$	11,026		$	23,553		$	32,035
Amortization of deferred gains included in operating expenses as reduction to rental expense		—			(8,037	)		(8,118	)
Reclass of gain to Retained Earnings		(11,026	)		—			—
Recognition of deferred gains included in losses on asset dispositions and impairments, net		—			(4,490	)		—
Other		—			—			(364	)
Balance at end of year	$	—		$	11,026		$	23,553

Deferred Gains - Vessel Sales to the Company’s 50% or Less Owned Companies. A portion of the gains realized from non-financed sales of the Company’s vessels to its 50% or less owned companies has been deferred and recorded in the accompanying consolidated balance sheets in deferred gains and other liabilities. In most instances, the sale of a Company vessel to a 50% or less owned company is considered a sale of a business in which the Company relinquishes control to its 50% or less owned company resulting in gain recognition; however, the Company defers gains to the extent of any uncalled capital commitment it has with the 50% or less owned company. Deferred gain activity related to these transactions for the years ended December 31 was as follows (in thousands):

	2019			2018			2017
Balance at beginning of year	$	793		$	1,453		$	1,875
Amortization of deferred gains included in losses on asset dispositions and impairments, net		—			(25	)		—
Other		(793	)		(635	)		(422	)
Balance at end of year	$	—		$	793		$	1,453

Foreign Currency Translation

Foreign Currency Translation. The assets, liabilities and results of operations of certain consolidated subsidiaries are measured using their functional currency, which is the currency of the primary foreign economic environment in which they operate. Upon consolidating these subsidiaries with the Company, their assets and liabilities are translated to U.S. dollars at currency exchange rates as of the consolidated balance sheet dates and their revenues and expenses are translated at the weighted average currency exchange rates during the applicable reporting periods. Translation adjustments resulting from the process of translating these subsidiaries’ financial statements are reported in other comprehensive loss in the accompanying consolidated statements of comprehensive loss.

Foreign Currency Transactions. Certain consolidated subsidiaries enter into transactions denominated in currencies other than their functional currency. Gains and losses resulting from changes in currency exchange rates between the functional currency and the currency in which a transaction is denominated are included in foreign currency losses, net in the accompanying consolidated statements of loss in the period in which the currency exchange rates change.

Accumulated Other Comprehensive Loss

Accumulated Other Comprehensive Loss. The components of accumulated other comprehensive loss were as follows (in thousands):

	SEACOR Marine Holdings Inc. Stockholders' Equity									Noncontrolling Interests
	Foreign Currency Translation Adjustments			Derivative Gains (Losses) on Cash Flow Hedges, net			Total			Foreign Currency Translation Adjustments			Derivative Gains (Losses) on Cash Flow Hedges, net			Other Comprehensive Loss
Year Ended December 31, 2016	$	(11,413	)	$	76		$	(11,337	)	$	(1,614	)	$	(17	)	$	(6,344	)
Other comprehensive (loss) income		4,397			703			5,100			257			18			5,375
Income tax (expense)⁽¹⁾		(6,179	)		(77	)		(6,256	)		—			—			(6,256	)
Year Ended December 31, 2017		(13,195	)		702			(12,493	)		(1,357	)		1		$	(7,225	)
Other comprehensive income		(2,277	)		(1,972	)		(4,249	)		(88	)		(12	)	$	(4,349	)
Income tax benefit (expense)		—			(46	)		(46	)		—			—			(46	)
Year Ended December 31, 2018		(15,472	)		(1,316	)		(16,788	)		(1,445	)		(11	)	$	(11,620	)
Other comprehensive loss		20,157			(1,994	)		18,163			—			—		$	18,163
Income tax benefit (expense)		—			173			173			—			—			173
Year Ended December 31, 2019	$	4,685		$	(3,137	)	$	1,548		$	(1,445	)	$	(11	)	$	6,716

(1)	For the year ended December 31, 2017, income tax expense included income tax provisions of $4.5 million recognized as a result of new U.S. tax legislation signed into law on December 22, 2017.

Loss Per Share

Loss Per Share. Basic loss per common share of the Company is computed based on the weighted average number of common shares issued and outstanding during the relevant periods. Diluted loss per common share of the Company is computed based on the weighted average number of common shares issued and outstanding plus the effect of potentially dilutive securities through the application of the treasury stock and if-converted methods. Dilutive securities for this purpose assumes restricted stock grants have vested, common shares have been issued pursuant to the exercise of outstanding stock options and common shares have been issued pursuant to the conversion of the Convertible Senior Notes. For the years ended December 31, 2019, 2018 and 2017, diluted loss per common share of the Company excluded 1,826,966 shares, 2,183,708 shares and 4,070,500 shares, respectively, issuable upon the conversion of the Convertible Senior Notes as the effect of their inclusion in the computation would be anti-dilutive. In addition, for the years ended December 31, 2019 and 2018, diluted loss per common share of the Company excluded 303,609 shares and 192,346 shares, respectively, of restricted stock and 913,569 and 805,566 outstanding stock options as the effect of their inclusion in the computation would be anti-dilutive. In 2019, the Company issued 109,600 performance share awards, of which 91,600 were still outstanding as of December 31, 2019. These performance share awards are not considered outstanding until such time as they would be probable of being exercised, therefore they were not included in the computation of earnings (loss) per share.

Recently Adopted Accounting Standards

Recently Adopted Accounting Standards. On May 28, 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2014-09, “Revenue from Contracts with Customers (Topic 606)” to clarify the principles for recognizing revenue and to develop a common revenue standard and disclosure requirements. The standard supersedes previous revenue recognition requirements and industry-specific guidance. Under the standard, revenue is recognized when a customer obtains control of promised goods or services in an amount that reflects the consideration the entity expects to receive in exchange for those goods or services. The Company adopted this standard on January 1, 2018 using the modified retrospective approach by recognizing the cumulative effect of initially applying the standard as an adjustment to the opening balance of retained earnings. The Company implemented the necessary changes to its business processes, systems and controls to support recognition and disclosure of this ASU upon adoption. The Company’s revenues are primarily based on leases or rental agreements with customers which are not addressed in the standard. As a result, the adoption of the accounting standard did not have a material effect on the Company’s consolidated financial position, results of operations or cash flows, but did result in increased disclosures related to revenue recognition policies.

On February 25, 2016, the FASB issued a comprehensive new leasing standard meant to improve transparency and comparability among companies by requiring lessees to recognize a lease liability and a corresponding lease asset for virtually all lease contracts. It also requires additional disclosures about leasing arrangements. The Company adopted the new standard on January 1, 2019 and applied the transition provisions of the new standard at its adoption date with recognition of a cumulative-effect adjustment to the opening balance of retained earnings. The adoption of the new standard had a material impact on the Company’s consolidated financial position, results of operations and cash flows. The adjustment to the Company’s balance sheet on January 1, 2019 included the addition of $33.7 million of right-of-use assets, $31.9 million in lease liability, and a cumulative-effect adjustment to the opening balance of retained earnings of $1.7 million for certain of its equipment, office and land leases. In addition, unamortized deferred gains for four vessels leased under sale-leaseback arrangements were fully recognized as an adjustment to the opening balance of retained earnings of $8.7 million, net of tax, ($11.0 million deferred gains net of $2.3 million deferred taxes).

On October 24, 2016, the FASB issued a new accounting standard, which requires companies to account for the income tax effects of intercompany sales and transfers of assets other than inventory. The Company adopted the new standard on January 1, 2018, resulting in a reduction of $12.1 million to the Company’s opening retained earnings.

New Accounting Pronouncements

New Accounting Pronouncements. On August 28, 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement (Topic 820). This new guidance modifies the disclosure requirements related to fair value measurement. The new guidance is effective for fiscal years beginning after December 15, 2019. The effects of this standard on our financial position or reporting will not be material.

On August 29, 2018, the FASB issued ASU No. 2018-15, Intangibles-Goodwill and Other-Internal-Use Software (Subtopic 350-40). The new guidance reduces complexity for the accounting for costs of implementing a cloud computing service arrangement and aligns the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software (and hosting arrangements that include an internal use software license). For public companies, the amendments in this ASU are effective for fiscal years, and interim periods within those fiscal years beginning after December 15, 2019. The effects of this standard on our financial position, results of operations or cash flows will not be material.

On June 30, 2016, the FASB issued ASU No. 2016-13, Financial Instruments-Credit Losses (Topic 326). This ASU represents a significant change in the Accounting for Credit Losses model by requiring The ASU introduced a new accounting model, the Current Expected Credit Losses model (CECL), which requires earlier recognition of credit losses and additional disclosures related to credit risk. The CECL model utilizes a lifetime expected credit loss measurement objective for the recognition of credit losses for loans and other receivables at the time the financial asset is originated or acquired. The expected credit losses are adjusted each period for changes in expected lifetime credit losses. This model replaces the multiple existing impairment models in current U.S. GAAP, which generally require that a loss be incurred before it is recognized. The new standard will also apply to financial assets arising from revenue transactions such as contract assets and accounts receivables and is effective for fiscal years beginning after December 15, 2019. Management has performed analysis and the new standard will not have a material impact on consolidated financial statements.

Share Based Compensation - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Payments for distribution of restricted stock, spin-off			$ 2,700
Employee service share-based compensation, nonvested awards, compensation cost not yet recognized, total	$ 6,500	$ 6,800	$ 5,200
Share-based compensation arrangement by share-based payment award, options, outstanding, exercise price, ending balance	$ 14.85
Share-based compensation arrangement by share-based payment award, options, outstanding, number, ending balance	913,569	805,566	613,700
Share-based compensation arrangement by share-based payment award, options, outstanding, weighted average remaining contractual term	8 years 5 months 19 days
Share-based compensation arrangement by share-based payment award, options, outstanding, intrinsic value	$ 0
Restricted Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Distribution of restricted stock in connection with spin-off			120,693
Share-based compensation arrangement by share-based payment award, equity instruments other than options, grants in period, weighted average grant date fair value	$ 13.28
Restricted Stock, Spin-off
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Allocated share-based compensation expense, total			$ 600
2017 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation arrangement by share-based payment award, number of shares authorized	2,174,000
Share-based compensation arrangement by share-based payment award, number of shares available for grant	567,424
Percentage of number of common stock shares outstanding	10.00%
Allocated share-based compensation expense, total	$ 5,300	$ 4,400	$ 800
Share-based compensation arrangement by share-based payment award, options, outstanding, exercise price, ending balance	$ 8.73	$ 9.99
Share-based compensation arrangement by share-based payment award, fair value assumptions, expected dividend rate	0.00%	0.00%
Share-based compensation arrangement by share-based payment award, fair value assumptions, expected volatility rate	51.10%	50.40%
Share-based compensation arrangement by share-based payment award, fair value assumptions, discount for postvesting restrictions	2.10%	2.79%
Share-based compensation arrangement by share-based payment award, fair value assumptions, expected term	9 years 9 months	6 years
Share-based compensation arrangement by share-based payment award, options, exercises in period, intrinsic value	$ 1,600
2017 Equity Incentive Plan \| Restricted Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Employee service share-based compensation, nonvested awards, compensation cost not yet recognized, period for recognition	1 year 3 months 29 days
Share-based compensation arrangement by share-based payment award, equity instruments other than options, grants in period, weighted average grant date fair value	$ 13.28	$ 21.63
2017 Equity Incentive Plan \| Restricted Stock \| Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation arrangement by share-based payment award, award vesting period	1 year
2017 Equity Incentive Plan \| Restricted Stock \| Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation arrangement by share-based payment award, award vesting period	4 years
2017 Equity Incentive Plan \| Employee Stock Option
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Employee service share-based compensation, nonvested awards, compensation cost not yet recognized, period for recognition	1 year 3 months
2017 Equity Incentive Plan \| Employee Stock Option \| Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation arrangement by share-based payment award, award vesting period	1 year
2017 Equity Incentive Plan \| Employee Stock Option \| Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation arrangement by share-based payment award, award vesting period	4 years
Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation arrangement by share-based payment award, number of shares authorized	300,000
Share-based compensation arrangement by share-based payment award, discount from market price, purchase date			85.00%
Period of common stock reserved for issuance	10 years

Income Taxes - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Taxes [Line Items]
Effective income tax rate reconciliation, at federal statutory Income tax rate, percent	21.00%	21.00%	35.00%
Income tax benefit and equity in earnings (losses)	(50.00%)
Increase (decrease) in transition tax liability	$ 2,300		$ 3,400,000
Current income tax expense (benefit), nonqualified withdrawal of funds from capital construction fund		$ 1,400,000
Income tax expense (benefit), continuing operations, adjustment of deferred tax (asset) liability			$ (3,900,000)
Effective income tax rate reconciliation, percent, total	9.60%	14.30%	63.20%
Exclusion of foreign subsidiaries with accumulated losses and withholding tax	7.20%	9.50%	3.10%
Noncontrolling interests	1.80%	(1.50%)	1.70%
Tax Cuts and Jobs Act of 2017, income tax expense (benefit)			$ 43,700,000
Interest expense suspended	$ 6,600,000	$ 3,600,000
Interest expense carryforward		10,200,000
Interest expense suspended, limitation percentage	30.00%
Operating loss carryforwards, percentage of taxable income, utilization limitation	80.00%
Operating loss carryforwards, total	$ 42,200,000	$ 94,500,000
Operating loss carryforwards, expiration period		20 years
State and Local Jurisdiction [Member]
Income Taxes [Line Items]
Operating loss carryforwards, valuation allowance, total	$ 1,300,000

Noncontrolling Interests in Subsidiaries - Schedule of Noncontrolling Interests in the Company's Consolidated Subsidiaries (Parenthetical) (Details)	Dec. 31, 2018
Windcat Workboats
Minority Interest [Line Items]
Noncontrolling interest, ownership percentage by noncontrolling owners	12.50%

Stockholders' Equity - Additional Information (Details)
€ in Millions, £ in Millions

1 Months Ended

12 Months Ended

Mar. 15, 2019

USD ($)

Mar. 15, 2019

GBP (£)

Mar. 15, 2019

EUR (€)

Jan. 25, 2019

USD ($)

Jan. 25, 2019

GBP (£)

Jan. 09, 2019

USD ($)

Vessel

Jun. 08, 2018

May 31, 2018

May 02, 2018

USD ($)

Apr. 26, 2018

Mar. 26, 2018

USD ($)

Feb. 08, 2018

USD ($)

Vessel

Apr. 30, 2018

USD ($)

Dec. 31, 2019

USD ($)

Dec. 31, 2018

USD ($)

Dec. 31, 2017

USD ($)

Jan. 01, 2019

USD ($)

Jan. 01, 2018

USD ($)

Cumulative Effect of New Accounting Principle in Period of Adoption

$ 10,416,000

$ (12,069,000)

Stock Issued During Period, Shares, New Issues | shares

103,213

Number of liftboat vessels operated | Vessel

^[1]

Common stock value

$ 219,000

$ 204,000

Adjustment to stockholders equity due to unamortized debt discount

$ 26,343,000

32,005,000

$ 400,000

Proceeds from issuance of private placement

$ 1,800,000

Class of warrant or right, exercised during period | shares

38,857

250,693

Common stock held in treasury in exchange for payment of warrants converted | shares

108

Carlyle Group | Convertible Senior Notes Converted to Warrants

Debt conversion, original debt, amount

$ 50,000,000

FGUSA Credit Facility

Debt agreement maximum borrowing capacity

131,100,000

FGUSA Credit Facility | Revolving Credit Facility

10,000,000

FGUSA Credit Facility | Term Loan

500,000

$ 9,500,000

Montco Offshore, LLC

Number of liftboat vessels operated | Vessel

Falcon Global USA LLC

Payments for debtor in possession obligations

$ 15,000,000

Windcat Workboats Facilities | Seabulk Overseas

Business acquisition, percentage of voting interests acquired

6.25%

100.00%

Business combination, consideration transferred, total

$ 1,400,000

£ 1.2

€ 1.2

$ 2,000,000

£ 1.6

Business acquisition, exchange for consideration | shares

50,000

Private Placement

Stock Issued During Period, Shares, New Issues | shares

603,872

56,900,000

750,000

Acquired | Vessel

Common stock value

$ 7,800

Retained Earnings

Cumulative Effect of New Accounting Principle in Period of Adoption

$ 10,416,000

$ (12,069,000)

Retained Earnings | Accounting Standards Update 2016-02

Cumulative Effect of New Accounting Principle in Period of Adoption

$ 10,400,000

$ (12,100)

[1]	Excludes three FSVs purchased from managed entities, one crew transfer vessel sold upon completion and one ERRV purchased from a joint venture.

Leases (Tables)

12 Months Ended

Dec. 31, 2019

Leases [Abstract]

Summary of Future Minimum Payments For Operating Leases

As of December 31, 2019, future minimum payments for operating leases for the years ended December 31 were as follows (in thousands):

2020	$	15,355
2021		7,128
2022		668
2023		621
2024		696
Years subsequent to 2024		4,437
		28,905
Interest component		(3,984	)
		24,921
Current portion of long-term operating lease liabilities		15,099
Long-term operating lease liabilities	$	9,822

Summary of Components of Leases Expense

For the year ended December 31, 2019, the components of lease expense were as follows (in thousands):

	2019
Operating lease expense	$	13,639
Short-term lease expense (lease duration of twelve months or less at lease commencement)		2,519
	$	16,158

Summary of Other Information Related to Operating Leases

For the year ended December 31, 2019, other information related to operating leases were as follows (in thousands except weighted average data):

	2019
Operating cash flows from operating leases	$	19,339
Right-of-use assets obtained for operating lease liabilities	$	35,246
Weighted average remaining lease term, in years		4.7
Weighted average discount rate		4.1	%

Document And Entity Information - USD ($) $ in Millions	12 Months Ended
Document And Entity Information - USD ($) $ in Millions	Dec. 31, 2019	Feb. 28, 2020	Jun. 28, 2019
Cover [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY
Trading Symbol	SMHI
Entity Registrant Name	SEACOR Marine Holdings Inc.
Entity Central Index Key	0001690334
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	true
Entity Ex Transition Period	true
Entity Shell Company	false
Title of 12(b) Security	Common stock
Security Exchange Name	NYSE
Entity File Number	1-37966
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	47-2564547
Entity Address, Address Line One	12121 Wickchester Lane
Entity Address, Address Line Two	Suite 500
Entity Address, City or Town	Houston
Entity Address, State or Province	TX
Entity Address, Postal Zip Code	77079
City Area Code	346
Local Phone Number	980-1700
Document Annual Report	true
Document Transition Report	false
Entity Common Stock, Shares Outstanding		21,881,489
Entity Public Float			$ 325.6
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Documents Incorporated by Reference	Portions of the Registrant’s definitive proxy statement for its 2020 Annual Meeting of Stockholders to be filed with the Securities and Exchange Commission (the "SEC") pursuant to Regulation 14A within 120 days after the end of the Registrant’s last fiscal year is incorporated by reference into Part III of this Annual Report on Form 10-K.

Subsequent Events

12 Months Ended

Dec. 31, 2019

Subsequent Events [Abstract]

Subsequent Events

22.	SUBSEQUENT EVENTS

On February 7, 2020, SEACOR Marine Holdings Inc. (“SEACOR Marine”), Falcon Global USA LLC (“FGUSA”), an indirect subsidiary of SEACOR Marine, and certain subsidiaries of FGUSA, entered into a Consent, Agreement and Omnibus Amendments agreement (the “Omnibus Amendment”) to that certain (i) $131.1 million term and revolving loan facility, dated as of February 8, 2018, with a syndicate of lenders administered by JP Morgan Chase Bank, N.A. (the “Credit Facility”) and (ii) obligation guaranty issued by SEACOR Marine, dated February 8, 2018, pursuant to which SEACOR Marine provides a guarantee of certain limited obligations of FGUSA under the Credit Facility (the “Guaranty”). The Omnibus Amendment provides for, among other things, (i) the extension from March 2020 to March 2021 of the commencement of monthly repayment of the term loan, with payments being the lesser of (a) $0.8 million per month and (b) the amount outstanding under the term loan and (ii) the extension of the term of the Guaranty for an additional one year from February 8, 2020 to February 8, 2021. As of February 7, 2020, there was $117.3 million of principal outstanding under the Credit Facility, comprised of $102.3 million of principal outstanding under the term loan facility and $15.0 million outstanding under the revolving loan facility.

Fair Value Measurements

12 Months Ended

Dec. 31, 2019

Fair Value Disclosures [Abstract]

Fair Value Measurements

11.	FAIR VALUE MEASUREMENTS

The fair value of an asset or liability is the price that would be received to sell an asset or transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. The Company utilizes a fair value hierarchy that maximizes the use of observable inputs and minimizes the use of unobservable inputs when measuring fair value and defines three levels of inputs that may be used to measure fair value. Level 1 inputs are quoted prices in active markets for identical assets or liabilities. Level 2 inputs are observable inputs other than quoted prices included in Level 1 that are observable for the asset or liability, either directly or indirectly, including quoted prices for similar assets or liabilities in active markets, quoted prices in markets that are not active, inputs other than quoted prices that are observable for the asset or liability, or inputs derived from observable market data. Level 3 inputs are unobservable inputs that are supported by little or no market activity and are significant to the fair value of the assets or liabilities.

The Company’s financial assets and liabilities as of December 31 that are measured at fair value on a recurring basis were as follows (in thousands):

	Level 1		Level 2		Level 3⁽¹⁾
2019
ASSETS
Construction reserve funds	$	12,893	$	—	$	—
LIABILITIES
Derivative instruments (included in other current liabilities)		—		3,009		—
Conversion Option Liability on Convertible Senior Notes		—		—		5,205
2018
ASSETS
Derivative instruments (included in other receivables)	$	—	$	419	$	—
Construction reserve funds		28,221		—		—
LIABILITIES
Derivative instruments (included in other current liabilities)		—		1,659		—
Conversion Option Liability on Convertible Senior Notes		—		—		5,276

(1)	For the year ended December 31, 2019, the Company recognized a $0.1 million gain in the fair market valuation of the Convertible Senior Notes, as valued by an independent third-party.

Level 3 Measurement. The fair value of the conversion option liability on the Convertible Senior Notes is estimated with significant inputs that are both observable and unobservable in the market and therefore is considered a Level 3 fair value measurement. The Company used a binomial lattice model that assumes the holders will maximize their value by finding the optimal decision between redeeming at the redemption price or converting into shares of Common Stock. This model estimates the fair value of the conversion option as the differential in the fair value of the notes including the conversion option compared with the fair value of the notes excluding the conversion option. The significant observable inputs used in the fair value measurement include the price of Common Stock and the risk-free interest rate. The significant unobservable inputs are the estimated Company credit spread and Common Stock volatility, which were based on comparable companies in the marine transportation and energy industries.

The estimated fair value of the Company’s other financial assets and liabilities as of December 31 were as follows (in thousands):

			Estimated Fair Value
	Carrying Amount		Level 1		Level 2		Level 3
2019
ASSETS
Cash, cash equivalents and restricted cash	$	87,047	$	87,047	$	—	$	—
Investments, at cost, in 50% or less owned companies (included in other assets)		132	see below
LIABILITIES
Long-term debt, including current portion		398,053		—		380,815		—
2018
ASSETS
Cash, cash equivalents and restricted cash	$	93,254	$	93,254	$	—	$	—
Investments, at cost, in 50% or less owned companies (included in other assets)		132	see below
LIABILITIES
Long-term debt, including current portion		404,666		—		388,949		—

The carrying value of cash, cash equivalents and restricted cash approximates fair value. The fair value of the Company’s long-term debt was estimated by using discounted cash flow analysis based on estimated current rates for similar types of arrangements. It was not practicable to estimate the fair value of the Company’s investments, at cost, in 50% or less owned companies because of the lack of a quoted market price and the inability to estimate fair value without incurring excessive costs. Considerable judgment was required in developing certain of the estimates of fair value and, accordingly, the estimates presented herein are not necessarily indicative of the amounts that the Company could realize in a current market exchange.

The Company’s non-financial assets and liabilities that were measured at fair value during the years ended December 31 were as follows (in thousands):

	Level 1		Level 2		Level 3
2019
ASSETS
Property and equipment:
AHTS	$	—	$	520	$	—
FSV		—		1,858		—
2018
ASSETS
Property and equipment:
AHTS	$	—	$	2,000	$	—
Liftboats		—		—		134,775
Specialty		—		4,500		—

Property and equipment. During the years ended December 31, 2019, 2018 and 2017 the Company recognized impairment charges of $12.0 million, $14.6 million, and $27.5 million, respectively, associated with certain offshore support vessels. The Level 2 fair values were determined based on the contracted sales prices of the property and equipment, sales prices of similar property and equipment or scrap value, as applicable. The Level 3 fair values were determined based on third-party valuations using significant inputs that are unobservable in the market. Due to limited market transactions, the primary valuation methodology applied by the appraisers was an estimated cost approach less estimated economic depreciation for comparably aged and conditioned assets less estimated economic obsolescence based on market data or utilization and rates per day worked trending of the vessels since 2014.

The significant unobservable inputs used in the fair value measurement for the AHTS fleet during 2018 listed above were contributed by MOI to wholly-owned subsidiaries of FGH and recorded at fair value. The Level 3 fair values were determined based on two separate third-party valuations using significant inputs that are unobservable in the market. Due to limited market transactions, the primary valuation methodology applied by both appraisers was an estimated cost approach less economic depreciation for comparable aged vessels. The Level 3 fair value of the vessels was based on a simple average between the two appraisals.

Investments, at equity, in 50% or less owned companies. During the year ended December 31, 2019, the Company marked its investments to zero in certain of its 50% of less owned companies. December 31, 2017, the Company marked its investments to fair value in certain of its 50% or less owned companies. The Level 2 fair values were determined based on the purchase price of acquired interests or sales prices of similar equipment held in the venture. The Level 3 fair values were determined based on third-party valuations using significant inputs that are unobservable in the market. The Company’s partner declined to participate in a capital call from Falcon Global during 2017 and, as a consequence, the Company obtained 100% voting control of Falcon Global in accordance with the terms of the operating agreement (see Note 5). Upon the change in control, the Company’s investment in Falcon Global was deemed to approximate fair value.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Schedule II - Valuation and Qualifying Accounts - Schedule of Valuation and Qualifying Accounts (Details) - USD ($)
$ in Thousands

12 Months Ended

Dec. 31, 2019

Dec. 31, 2018

Dec. 31, 2017

Valuation And Qualifying Accounts [Abstract]

Allowance for doubtful accounts (deducted from trade and notes receivable)

$ 860

$ 4,039

$ 5,359

Allowance for doubtful accounts (deducted from trade and notes receivable)

(405)

(928)

(1,283)

Allowance for doubtful accounts (deducted from trade and notes receivable)

^[1]

(2,251)

(37)

Allowance for doubtful accounts (deducted from trade and notes receivable)

$ 455

$ 860

$ 4,039

[1]	Trade receivable amounts deemed uncollectible that were removed from accounts receivable and allowance for doubtful accounts.

Leases - Summary of Future Minimum Payments For Operating Leases (Details) $ in Thousands	Dec. 31, 2019 USD ($)
Leases [Abstract]
2020	$ 15,355
2021	7,128
2022	668
2023	621
2024	696
Years subsequent to 2024	4,437
Operating lease payments due	28,905
Interest component	(3,984)
Total operating leases	24,921
Current portion of operating lease liabilities	15,099
Long-Term Operating Lease Liabilities	$ 9,822

Noncontrolling Interests in Subsidiaries - Schedule of Noncontrolling Interests in the Company's Consolidated Subsidiaries (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Minority Interest [Line Items]
Noncontrolling interest	$ 21,432	$ 29,404
Falcon Global
Minority Interest [Line Items]
Noncontrolling interest, ownership percentage by noncontrolling owners	28.00%
Noncontrolling interest	$ 21,119	$ 26,989
Windcat Workboats
Minority Interest [Line Items]
Noncontrolling interest, ownership percentage by noncontrolling owners		12.50%
Noncontrolling interest		$ 2,115
Other Noncontrolling Interests
Minority Interest [Line Items]
Noncontrolling interest, ownership percentage by noncontrolling owners	1.80%
Noncontrolling interest	$ 313	$ 300

Supplemental Information for Statements of Cash Flows - Schedule of Supplemental Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Supplemental Cash Flow Information [Abstract]
Income taxes (paid) refunded, net	$ 1,999	$ (316)	$ 33,773
Interest paid, excluding capitalized interest	$ 22,452	$ 21,031	$ 9,216

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Statement Of Financial Position [Abstract]
Trade receivables, allowance for doubtful accounts	$ 455	$ 860
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized (in shares)	10,000,000	10,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	60,000,000	60,000,000
Common stock, shares issued (in shares)	21,928,674	20,443,215
Shares held in treasury (in shares)	47,185	4,007

Quarterly Financial Information (Unaudited) - Selected Financial Information for Interim Quarterly Periods (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Operating Revenues	$ 49,070	$ 54,700	$ 52,812	$ 44,910	$ 58,897	$ 58,169	$ 47,871	$ 38,630	$ 201,492	$ 203,567	$ 123,421
Operating Loss	(10,497)	(3,355)	(17,640)	(21,034)	(11,253)	(12,207)	(20,842)	(24,206)	(52,526)	(68,509)	(129,644)
Net (Loss) Income:
Continuing Operations	(19,176)	(10,341)	(31,438)	(28,273)	(7,780)	(17,706)	(26,505)	(31,430)	(89,228)	(83,422)	(39,529)
Discontinued Operations	(2,742)	(7,899)	1,174		(189)	1,940	(124)	(258)
Net Loss	(21,918)	(18,240)	(30,264)	(28,273)	(7,969)	(15,766)	(26,629)	(31,688)	(98,695)	(82,052)	(38,540)
Net Loss attributable to SEACOR Marine Holdings Inc:	$ (20,455)	$ (18,444)	$ (28,389)	$ (25,549)	$ (7,794)	$ (15,957)	$ (25,024)	$ (28,833)	$ (92,837)	$ (77,608)	$ (32,901)
Basic and Diluted Income (Loss) Per Common Share and Warrants of SEACOR Marine Holdings Inc.
Continuing operations	$ (0.74)	$ (0.49)	$ (1.31)	$ (1.16)	$ (0.39)	$ (0.85)	$ (1.18)	$ (1.63)	$ (3.55)	$ (3.77)	$ (1.93)
Discontinued operations	(0.12)	(0.29)	0.10	0.05	0.04	0.14	(0.01)	(0.01)	(0.40)	0.07	0.06
Basic and Diluted Income (Loss) Per Common Share and Warrants	$ (0.86)	$ (0.78)	$ (1.21)	$ (1.11)	$ (0.35)	$ (0.71)	$ (1.19)	$ (1.64)	$ (3.95)	$ (3.70)	$ (1.87)

Consolidated Statements of Comprehensive Loss (Parenthetical)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement Of Income And Comprehensive Income [Abstract]
Reclassification of derivative losses on cash flow hedges to equity in earnings	50.00%	50.00%	50.00%

Equipment Acquisitions and Dispositions (Tables)

12 Months Ended

Dec. 31, 2019

Property Plant And Equipment [Abstract]

Schedule of Vessel Acquired and Disposed

	2019 ⁽¹⁾		2018		2017
FSV		2		—		6
Supply		2		—		5
Liftboat		—		6		—
CTV		2		2		—
		6		8		11

(1)	Excludes three FSVs purchased from managed entities, one crew transfer vessel sold upon completion and one ERRV purchased from a joint venture.

	2019 ⁽¹⁾		2018 ⁽²⁾		2017 ⁽³⁾
AHTS		1		1		—
FSV		5		9		—
Supply		5		—		1
Crew transfer		—		1		—
Liftboats		3		2		2
		14		13		3

(1)

(2)	Excludes three ERRVs from discontinued operations

(3)	Excludes one ERRV from discontinued operations.

Share Based Compensation

12 Months Ended

Dec. 31, 2019

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Share Based Compensation

16.	SHARE BASED COMPENSATION

Equity Incentive Plan. During 2017, the Company adopted the SEACOR Marine Holdings Inc. 2017 Equity Incentive Plan (the “2017 Plan”). The 2017 Plan authorizes the Compensation Committee, or another committee designated by the Board and made up of two or more non-employee directors and outside directors, to provide equity-based or other incentive-based compensation for the purpose of attracting and retaining the Company and its affiliates’ directors, employees and certain consultants, and providing those directors, employees and consultants incentive opportunities and rewards for superior performance. The Board has authorized the issuance of 2,174,000 shares of Common Stock in connection with awards pursuant to the 2017 Plan, which was equal to 10% of the total number shares of SEACOR Marine Common Stock outstanding at the time of authorization. The types of awards under the 2017 Plan may include stock options, stock appreciation rights, restricted stock and restricted stock units, performance awards and other stock-based awards. As of December 31, 2019, a total of 567,424 shares remained available for issuance under the 2017 Plan.

Restricted stock typically vests from one to four years after the date of grant and options to purchase shares of Common Stock typically vest and become exercisable from one to four years after date of grant. Options to purchase shares of Common Stock granted under the 2017 Plan expire no later than the tenth anniversary of the date of grant. In the event of a participant’s death, retirement, termination by the Company without cause or a change in control of the Company, as defined in the 2017 Plan, restricted stock vests immediately and in the event of participant’s death or retirement, options to purchase shares of Common Stock vest and become immediately exercisable.

Distribution of SEACOR Marine Restricted Stock by SEACOR Holdings. Certain officers and employees of the Company previously received compensation through participation in SEACOR Holdings share award plans. Pursuant to the Employee Matters Agreement with SEACOR Holdings, participating Company personnel vested in all outstanding SEACOR Holdings share awards upon the Spin-off in 2017 and received SEACOR Marine restricted stock from the Spin-off distribution in connection with outstanding SEACOR Holdings restricted stock held. Therefore, the Company paid SEACOR Holdings $2.7 million upon completion of the Spin-off for the distribution of 120,693 shares of SEACOR Marine restricted stock, which is being amortized over the participants’ remaining original vesting periods.

Employee Stock Purchase Plan. During 2017, the Company adopted the SEACOR Marine Holdings Inc. 2017 Employee Stock Purchase Plan (the “Marine ESPP”). The Marine ESPP, if implemented by the Company’s board of directors, will permit the Company to offer shares of its Common Stock for purchase by eligible employees at a price equal to 85% of the lesser of (i) the fair market value of a share of its Common Stock on the first day of the offering period or (ii) the fair market value of a share of its Common Stock on the last day of the offering period. There are 300,000 shares of the Company’s Common Stock reserved for issuance under the Marine ESPP during the ten years following its adoption.

Share Award Transactions. The following transactions have occurred in connection with the Company’s share-based compensation under the 2017 Plan during the years ended December 31:

	2019			2018
Director Stock Awards Granted		30,197			19,285

Restricted Stock Activity:
Outstanding as of the beginning of year		192,346			121,693
Granted - 2017 Plan		245,400	⁽¹⁾		120,600
Vested		131,937			49,947
Forfeited		2,200			—
Outstanding as of the end of year		303,609			192,346

Stock Option Activity:
Outstanding as of the beginning of year		805,566			613,700
Granted - 2017 Plan		230,503			258,491
Exercised		113,750			66,625
Forfeited		8,750			—
Outstanding as of the end of year		913,569			805,566

(1)	Excludes 91,600 grants of performance-based stock units that are not considered outstanding until such time that they become probable to vest.

During the year ended December 31, 2019, the Company recognized $5.3 million of compensation expense related to stock awards, restricted stock and stock options granted to employees and directors under the 2017 Plan. As of December 31, 2019, the Company had approximately $6.5 million in total unrecognized compensation costs. The weighted average period over which the compensation cost of non-vested awards will be recognized is approximately 1.25 and 1.33 years for stock options and restricted stock, respectively.

During the year ended December 31, 2018, the Company recognized $4.4 million of compensation expense related to stock awards, restricted stock and stock options granted to employees and directors under the 2017 Plan. As of December 31, 2018, the Company had approximately $6.8 million in total unrecognized compensation costs.

During the year ended December 31, 2017, the Company recognized $0.8 million of compensation expense related to stock awards, restricted stock and stock options granted to employees and directors under the 2017 Plan and $0.6 million of compensation expense related to SEACOR Marine restricted stock distributed to employees by SEACOR Holdings in connection with the Spin-off (collectively referred to as “share awards”). As of December 31, 2017, the Company had approximately $5.2 million in total unrecognized compensation costs.

The weighted average fair value of restricted stock granted under the 2017 Plan was $13.28 and $21.63 for the year ended December 31, 2019 and 2018, respectively. The fair value was based the closing price of the Company’s stock on the day of the grant. The weighted average fair value of stock options granted under the 2017 Plan was $8.73 and $9.99 for the year ended December 31, 2019 and 2018, respectively. The fair value of each option granted during the years ended December 31, 2019 and 2018, was estimated on the date of grant using the Black-Scholes option pricing model with the following assumptions: (a) no dividend yield; (b) weighted average expected volatility of 51.1 and 50.4, respectively; (c) weighted average discount rate of 2.1% and 2.79%, respectively and (d) expected life of 9.75 and 6.00 years, respectively. The intrinsic value of stock options exercised during 2019 was $1.6 million.

During the year ended December 31, 2019, the number of shares and the weighted average grant price of restricted stock transactions were as follows:

	Restricted Stock
	Number of Shares		Weight Average Grant Price
Non-Vested as of December 31, 2018		192,346	$	22.32
Granted		245,400		13.28
Vested		131,937		13.45
Forfeited		2,200		17.26
Non-Vested as of December 31, 2019		303,609		20.46

During the year ended December 31, 2019, the number of shares and the weighted average exercise price on stock option transactions were as follows:

	Stock Options
	Number of Shares		Weight Average Grant Price
Non-Vested as of December 31, 2018		805,566	$	14.81
Granted		230,503		8.73
Exercised		113,750		13.98
Forfeited		8,750		20.93
Non-Vested as of December 31, 2019		913,569		14.85
Exercisable as of December 31, 2019⁽¹⁾		408,075		14.69

(1)	The weighted average remaining contractual term is 8.23 years.

As of December 31, 2019, there were 913,569 stock options outstanding with a weighted average exercise price of $14.85 and a weighted average remaining contractual term of 8.47 years. As of December 31, 2019, there was no aggregate intrinsic value for options outstanding.

Schedule II - Valuation and Qualifying Accounts

12 Months Ended

Dec. 31, 2019

Valuation And Qualifying Accounts [Abstract]

Schedule II - Valuation and Qualifying Accounts

SEACOR MARINE HOLDINGS INC.

SCHEDULE II - VALUATION AND QUALIFYING ACCOUNTS

For the Years Ended December 31, 2019, 2018 and 2017

(in thousands)

Description	Balance Beginning of Year		Charges (Recoveries) to Cost and Expenses			Deductions⁽¹⁾			Balance End of Year
Year Ended December 31, 2019
Allowance for doubtful accounts (deducted from trade and notes receivable)	$	860	$	(405	)	$	—		$	455
Year Ended December 31, 2018
Allowance for doubtful accounts (deducted from trade and notes receivable)	$	4,039	$	(928	)	$	(2,251	)	$	860
Year Ended December 31, 2017
Allowance for doubtful accounts (deducted from trade and notes receivable)	$	5,359	$	(1,283	)	$	(37	)	$	4,039

(1)	Trade receivable amounts deemed uncollectible that were removed from accounts receivable and allowance for doubtful accounts.

Long Term Debt

12 Months Ended

Dec. 31, 2019

Debt Disclosure [Abstract]

Long Term Debt

8.	LONG-TERM DEBT

The Company’s long-term debt obligations as of December 31 were as follows (in thousands):

	2019			2018
Convertible Senior Notes	$	125,000		$	125,000
SEACOR Marine Foreign Holdings Loan Facility		113,750			126,750
Falcon Global USA Term Loan Facility		102,349			109,099
Sea-Cat Crewzer III Term Loan Facility		24,128			25,989
Windcat Workboats Facilities		24,730			24,850
Falcon Global USA Revolver		15,000			15,000
SEACOR 88/888 Term Loan		11,000			11,000
SEACOR Alps		10,534			—
BNDES Equipment Construction Finance Notes		3,332			5,284
		429,823			442,972
Portion due within one year		(17,802	)		(16,812	)
Debt discount		(26,343	)		(32,005	)
Issue costs		(5,427	)		(6,301	)
	$	380,251		$	387,854

The Company’s contractual long-term debt maturities for the years ended December 31 were as follows (in thousands):

2020	$	17,802
2021		51,789
2022		26,007
2023		231,674
2024		90,800
Years subsequent to 2024		11,752
	$	429,823

As of December 31, 2019, the Company is in compliance with all debt covenants and lender requirements.

SEACOR ALPS On September 30, 2019, the Company took possession of the SEACOR Alps, a Rolls Royce UT771CDL designed diesel electric powered PSV of 3,800 tons deadweight capacity with dynamic position class 2 and firefighting class 1 notations. As part of this transaction, the shipbuilder financed 70% of the total purchase price pursuant to a deferred payment agreement. This loan bears interest at 5% and is due and payable in 2023.

SEACOR Marine Foreign Holdings.

On September 26, 2018, SEACOR Marine Foreign Holdings Inc. (“SMFH”), a wholly-owned subsidiary of the Company, entered into a $130.0 million loan facility with a syndicate of lenders administered by DNB Bank ASA (the “SMFH Loan Facility”). Subject to Amendment No. 1 and Amendment No. 2 described below, SMFH’s obligations pursuant to the SMFH Loan Facility were initially secured by mortgages on 20 vessels owned by the Company’s vessel owning subsidiaries as well as an assignment of earnings from those subsidiaries. The loan matures in 2023 and bears interest at a variable rate based on LIBOR (currently 5.875%). The obligations of SMFH under the SMFH Loan Facility are guaranteed by SEACOR Marine (the “SMFH Loan Facility Guaranty”). The proceeds from the SMFH Loan Facility were used to pay off all obligations under other credit facilities of subsidiaries of the Company (Falcon Global International Term Loan Facility, Sea-Cat Crewzer II Term Loan Facility, Sea-Cat Crewzer Term Loan Facility and C-Lift Acquisition Notes totaling $101.3 million, consisting of $99.9 million principal and $1.4 million accrued interest), resulting in a net increase in term debt of $30.1 million. Principal payments of $3.3 million per quarter under the SMFH Loan Facility began in December 2018. As a result of this transaction, the Company recognized a loss of $0.6 million upon the extinguishment of debt. In October 2018, the Company entered into an interest rate swap agreement on the notional value at inception of $65.0 million related to this debt. The SMFH Loan Facility provides for customary events of default and has customary affirmative and negative covenants for transactions of this type that are applicable to SEACOR Marine, SMFH and its subsidiaries.

On August 6, 2019, SEACOR Marine, SMFH, and certain vessel-owning subsidiaries of SEACOR Marine, entered into Amendment No. 1 to the SMFH Loan Facility and SMFH Loan Facility Guaranty (the “Amendment No. 1”), which provided for, among other things, (i) the release of one vessel from a mortgage securing the SMFH Loan Facility and the substitution of mortgages over two other vessels owned by vessel-owning subsidiaries of SEACOR Marine, and (ii) the modification of certain financial maintenance and restrictive covenants contained in the SMFH Loan Facility or the SMFH Loan Facility Guaranty, including with respect to asset maintenance, vessel collateral releases, EBTIDA coverage ratios and the payment of dividends and distributions. On November 26, 2019, SEACOR Marine, SMFH, and certain vessel-owning subsidiaries of SEACOR Marine, entered into Amendment No. 2 to the SMFH Loan Facility, as amended by Amendment No. 1 (the “Amendment No. 2”), which provided for, among other things, (i) the release of six vessels from mortgages securing the Credit Facility and the substitution of mortgages over three other vessels owned by vessel-owning subsidiaries of SEACOR Marine and (ii) the bareboat registration in Nigeria of a vessel subject to a mortgage securing the Credit Facility.

No management fees were charged to OSV Partners for the year ended December 31, 2019, as management fees were abated. For the years ended December 31, 2018 and 2017, the Company received $0.6 million, of vessel management fees from OSV Partners for each year.

Convertible Senior Notes. On December 1, 2015, the Company issued $175.0 million in aggregate principal amount of its Convertible Senior Notes (the “Convertible Senior Notes”), at an interest rate of 3.75%, initially due December 1, 2022, (subsequently amended to December 2, 2023 as described below) to investment funds managed and controlled by the Carlyle Group (collectively “Carlyle”). The Convertible Senior Notes are convertible into shares of Common Stock at a conversion rate of 23.26 shares per $1,000 in principal amount of such notes, subject to certain conditions, or, into Warrants to purchase an equal number of shares of Common Stock at an exercise price of $0.01 per share in order to facilitate the Company’s compliance with the provisions of the Jones Act. The indenture governing the Convertible Senior Notes contains customary events of default with respect to the Convertible Senior Notes.

Upon completion of the Spin-off, the Company bifurcated the embedded conversion option liability of $27.3 million from the Convertible Senior Notes and recorded an additional debt discount (see Notes 10 and 11). The adjusted unamortized debt discount and issue costs are being amortized as additional non-cash interest expense over the remaining maturity of the debt for an overall effective interest rate of 7.95% and the changes in the fair value of the bifurcated derivative are recorded as derivative income or loss.

On May 2, 2018, the Company and Carlyle entered into an exchange transaction (the “Exchange”) pursuant to which Carlyle exchanged $50 million in principal amount of the Convertible Senior Notes for Warrants to purchase 1,886,792 shares of Common Stock (to facilitate compliance with the provisions of the Jones Act) at an exercise price of $0.01 per share, subject to adjustments (the “Carlyle Warrants”), representing an implied exchange rate of approximately 37.73 shares per $1,000 in principal amount of the Convertible Senior Notes (equivalent to an exchange price of $26.50 per share). The Carlyle Warrants have a 25-year term, which commenced May 2, 2018. The Company and Carlyle also amended the $125.0 million in principal amount of Convertible Senior Notes that remained outstanding following the Exchange to (i) increase the interest rate from 3.75% per annum to 4.25% per annum and (ii) extend the maturity date of the Convertible Senior Notes by 12 months to December 1, 2023. Interest on the Convertible Senior Notes is payable semi-annually on June 15 and December 15 of each year.

Falcon Global USA. On February 8, 2018, a wholly-owned subsidiary of SEACOR Marine and MOI formed and capitalized a joint venture named Falcon Global Holdings LLC. In connection therewith and MOI’s plan of reorganization, which was confirmed on January 18, 2018, MOI emerged from its Chapter 11 bankruptcy case. In accordance with the terms of a Joint Venture Contribution and Formation Agreement, the Company and MOI contributed certain liftboat vessels and other related assets to FGH and its designated subsidiaries and FGH and its designated subsidiaries assumed certain operating liabilities and indebtedness associated with the liftboat vessels and related assets. On February 8, 2018, Falcon Global USA LLC (“FGUSA”), a wholly-owned subsidiary of FGH, paid $15.0 million of MOI’s debtor-in-possession obligations and entered into a $131.1 million credit agreement comprised of a $116.1 million term loan (the “FGUSA Term Loan”) and a $15.0 million revolving loan facility (the “FGUSA Revolving Loan Facility”) bearing interest at a variable rate (currently 6.3125%), maturing in 2024 and secured by 15 vessels owned by wholly-owned subsidiaries of FGUSA (collectively, the “FGUSA Credit Facility”). The full amount of the FGUSA Term Loan and other amounts paid by affiliates of MOI satisfied in full the amounts outstanding under MOI’s pre-bankruptcy petition credit facilities. In connection with the FGUSA Credit Facility, SEACOR Marine issued a limited obligation guaranty, dated February 8, 2018, pursuant to which SEACOR Marine guaranteed certain interest payments and participation fees under the FGUSA Credit Facility until February 8, 2020 (the “Guaranty”). Except as provided in the Guaranty, the FGUSA Credit Facility, is non-recourse to SEACOR Marine and its subsidiaries other than FGUSA. The Company performed a fair market valuation of the debt reflecting a debt discount of $10.0 million, which will be amortized over the life of the FGUSA Credit Facility. During the year ending December 31, 2018, the Company borrowed $15.0 million under the FGUSA Revolving Loan Facility for working capital purposes and made principal payments of $7.0 million under the term loan facility after sale of two collateralized vessels. The Company consolidates FGH as the Company holds 72% of the equity interest in FGH and is entitled to appoint a majority of the board of managers of FGH.

Sea-Cat Crewzer III Term Loan Facility. On April 21, 2016, Sea-Cat Crewzer III LLC (“Sea-Cat Crewzer III”) entered into a €27.6 million term loan facility (payable in U.S. dollars) secured by the vessel owned by Sea-Cat Crewzer III and fully guaranteed by SEACOR Marine (the “Sea-Cat Crewzer III Loan Facility”). Borrowings under the facility bear interest at a Commercial Interest Reference Rate, currently 2.76%. During the years ended December 31, 2017 and 2016, Sea-Cat Crewzer III drew $7.1 million and $22.8 million, respectively, under the facility and incurred issue costs of $2.7 million in 2016 related to this facility. During the years ended December 31, 2018 and 2017, Sea-Cat Crewzer III made scheduled payments of $3.1 million and $0.6 million, respectively, related to this facility. On December 26, 2019, Sea-Cat Crewzer III, SEACOR Marine, Banco Santander S.A. (as mandated lead arranger and agent), and Santander Bank, N.A. (as lender) entered into Amendment No. 1 to the Sea-Cat Crewzer III Loan Facility, which provided for, among other things, an increase to the maximum debt to capitalization ratio required to be maintained thereunder.

Windcat Workboats Facilities. On May 24, 2016, Windcat Workboats entered into a €25.0 million revolving credit facility secured by 38 of the Company’s CTV fleet. Borrowings under the facility bear interest at variable rates based on EURIBOR plus a margin ranging from 3.00% to 3.30% per annum plus mandatory lender costs and mature in 2021. The Company is currently in negotiations to extend the maturity to 2022. A quarterly commitment fee is payable based on the unfunded portion of the commitment amount at rates ranging from 1.20% to 1.32% per annum. During the year ended December 31, 2016, Windcat Workboats drew $23.5 million (€21.0 million) under the facility to repay all of its then outstanding debt totaling $22.9 million and incurred issuance costs of $0.6 million related to this facility.

During the year ended December 31, 2018, the Company converted €6.0 million denominated debt to pound sterling denominated debt, paying off approximately $7.5 million in euro denominated debt and borrowing approximately $8.5 million in pound sterling denominated debt, resulting in a net increase in USD borrowings of $1.0 million to be used for future capital commitments.

SEACOR 88/888. On July 5, 2018, a wholly-owned subsidiary of SEACOR Marine entered into a new term loan of $11.0 million and used the funds to acquire two vessels that were previously managed (but not owned) by the Company. The term loan matures in 2023, bears interest at a variable rate (currently 5.5625%) and is secured by the two vessels. SEACOR Marine provided a limited guaranty of such loan under which claims recoverable from SEACOR Marine shall not exceed the lesser of (x) $5.5 million and (y) 50% of the obligations outstanding at the time a claim is made thereunder. In October 2018, the Company entered into an interest rate swap agreement on the notional value at inception of $5.5 million related to this loan.

BNDES Equipment Construction Finance Notes. The Company financed the construction of two offshore support vessels in Brazil with Banco Nacional de Desenvolvimento Economico e Social (“BNDES”), a Brazilian government-owned entity. The notes are secured by a first mortgage on these vessels and guaranteed by SEACOR Holdings. The notes bear interest at 4.00% per annum, require monthly principal and interest payments, and mature in July through October 2021. During the years ended December 31, 2019, 2018 and 2017, the Company made scheduled payments of $2.0 million, $2.0 million and $2.0 million, respectively.

Falcon Global International Term Loan Facility. On August 3, 2015, Falcon Global International entered into a term loan facility to finance the construction of two foreign-flag liftboats. The facility consisted of two tranches: (i) a $62.5 million facility to fund the construction costs of the liftboats (“Tranche A”) and (ii) a $18.0 million facility for certain project costs (“Tranche B”). The facility was secured by the liftboats and is repayable over a five-year period that began after the completion of the construction of the liftboats and matures June 30, 2022. On November 3, 2017, Falcon Global International executed an amendment to its term loan facility, at a cost of $0.2 million, that required Falcon Global to maintain a debt service coverage ratio and a minimum cash balance on hand in excess of defined thresholds. In addition, the amendment required SEACOR Marine, as guarantor, to maintain a debt to capital ratio below a defined threshold and a minimum cash balance on hand in excess of a defined threshold.

In March 2017, the Company’s partner declined to participate in a capital call from Falcon Global International and, as a consequence, the Company obtained 100% voting control of Falcon Global International in accordance with the terms of the operating agreement. The Company consolidated into its financial statements Falcon Global International’s then outstanding debt under this facility of $58.3 million, net of issue costs of $1.0 million, effective March 31, 2017 (see Note 5). During April 2017, the Tranche B facility was canceled prior to any funding. During the nine months ended December 31, 2017, Falcon Global made scheduled payments of $4.4 million under Tranche A.

During the year ended December 31, 2018, Falcon Global International made scheduled payments of $3.0 million. The remaining principal balance of $51.9 million was paid off with the proceeds of SEACOR Marine Foreign Holdings Syndicated Facility on September 28, 2018.

Sea-Cat Crewzer II Term Loan Facility. On April 28, 2017, the Company acquired a 100% controlling interest in Sea-Cat Crewzer II through the acquisition of its partners’ 50% ownership interest (see Notes 3 and 5). Sea-Cat Crewzer II had a term loan facility that matured in 2019 which was secured by a first preferred mortgage on its vessels. On December 19, 2017, Sea-Cat Crewzer II executed an amendment, at a cost of $0.1 million, that replaced SEACOR Holdings with SEACOR Marine as guarantor and required SEACOR Marine to maintain a debt to capital ratio below a defined threshold and a minimum cash balance on hand in excess of a defined threshold. The facility called for quarterly payments of principal and interest with a balloon payment of $17.3 million due at maturity. The interest rate was fixed at 1.52%, inclusive of an interest rate swap, plus a margin ranging from 2.10% to 2.75% subject to the level of funded debt (overall rate of 5.64% as of December 31, 2017). In the year ended December 31, 2017, the Company made scheduled payments of $1.2 million.

During the year ended December 31, 2018, Sea-Cat Crewzer II made scheduled payments of $1.8 million. The remaining principal balance of $19.1 million was paid off by the SEACOR Marine Foreign Holdings Syndicated Facility on September 28, 2018.

Sea-Cat Crewzer Term Loan Facility. On April 28, 2017, the Company acquired a 100% controlling interest in Sea-Cat Crewzer through the acquisition of its partners’ 50% ownership interest (see Notes 3 and 5). Sea-Cat Crewzer had a term loan facility that matures in 2019 which was secured by a first preferred mortgage on its vessels. On December 19, 2017, Sea-Cat Crewzer executed an amendment, at a cost of $0.1 million, that replaced SEACOR Holdings with SEACOR Marine as guarantor and required SEACOR Marine to maintain a debt to capital ratio below a defined threshold and a minimum cash balance on hand in excess of a defined threshold. The facility called for quarterly payments of principal and interest with a balloon payment of $15.3 million due at maturity. The interest rate was fixed at 1.52%, inclusive of an interest rate swap, plus a margin ranging from 2.10% to 2.75% subject to the level of funded debt (overall rate of 5.64% as of December 31, 2017). In the year ended December 31, 2017, the Company made scheduled payments of $1.1 million.

During the year ended December 31, 2018, Sea-Cat Crewzer made scheduled payments of $1.6 million. The remaining principal balance of $16.9 million was paid off by the SEACOR Marine Foreign Holdings Syndicated Facility on September 28, 2018.

Letters of Credit. As of December 31, 2019, the Company had outstanding letters of credit totaling $0.5 million for one lease obligation and labor and performance guarantees.

Related Party Transactions

12 Months Ended

Dec. 31, 2019

Related Party Transactions

17.	RELATED PARTY TRANSACTIONS

Transactions with SEACOR Holdings. The Company provided services of $0.1 million to SEACOR Holdings during the year ended December 31, 2017.

In connection with the Spin-off, SEACOR Marine entered into certain agreements with SEACOR Holdings that govern SEACOR Marine’s relationship with SEACOR Holdings following the Spin-off, including a Distribution Agreement, two Transition Services Agreements, an Employee Matters Agreement and a Tax Matters Agreement.

As of December 31, 2019, SEACOR Holdings had guaranteed $22.8 million for various obligations of the Company, including performance obligations under sale-leaseback arrangements (see Note 7) and invoiced amounts for funding deficits under the MNOPF (see Note 15). As of December 31, 2018, SEACOR Holdings had guaranteed $40.6 million for various obligations of the Company, including: BNDES Equipment Construction Finance Notes (see Note 8); letters of credit issued on behalf of the Company; performance obligations under sale-leaseback arrangements (see Note 7); and invoiced amounts for funding deficits under the MNOPF (see Note 15). Pursuant to the Transition Services Agreement with SEACOR Holdings, SEACOR Holdings charges the Company a fee of 0.5% on outstanding guaranteed amounts, which declines as the guaranteed obligations are settled by the Company. The Company recognized guarantee fees in connection with sale-leaseback arrangements of $0.2 million, $0.3 million and $0.3 million during 2019, 2018 and 2017, respectively, as additional leased-in equipment operating expenses in the accompanying consolidated statements of loss. Guarantee fees paid to SEACOR Holdings for all other obligations are recognized as SEACOR Holdings guarantee fees in the accompanying consolidated statements of loss.

Pursuant to one of the Transitions Services Agreements with SEACOR Holdings, the Company is obligated to reimburse SEACOR Holdings up to 50% of the severance and restructuring costs actually incurred by SEACOR Holdings as a result of the Spin-off up to, but not in excess of, $6.0 million (such that the Company shall not be obligated to pay more than $3.0 million). As of December 31, 2017, the Company had reimbursed SEACOR Holdings severance and restructuring costs of $0.7 million, which were recognized as additional administrative and general expenses in the accompanying consolidated statements of loss. There was no such reimbursement for the years ended December 31, 2019 and 2018.

Following the completion of the Spin-off, the Company is no longer charged for management fees or shared services allocation (see below) for administrative support by SEACOR Holdings; however, the Company continues to be supported by SEACOR Holdings for corporate services pursuant to the Transition Services Agreements with SEACOR Holdings under which it was initially charged $6.3 million annually for these services. The fees incurred have declined as the services and functions provided by SEACOR Holdings are terminated and replicated within the Company. For the year ended December 31, 2019, 2018, and 2017, the Company incurred fees of $0.6 million, $4.5 million and $3.3 million, respectively, for these services that were recognized as additional administrative and general expenses in the accompanying consolidated statements of loss.

Prior to the Spin-off, certain costs and expenses of the Company were borne by SEACOR Holdings and charged to the Company. These costs and expenses are included in both operating and administrative and general expenses in the accompanying consolidated statements of loss and are summarized as follows for the year ended December 31, 2017 (in thousands):

	2017
Participation in SEACOR Holdings employee benefit plans	$	899
Participation in SEACOR Holdings share award plans		8,383
Shared services allocation for administrative support		1,932
	$	11,214

•

SEACOR Holdings maintained self-insured health benefit plans for participating employees, including those of the Company, and charged the Company for its share of total plan costs incurred based on the percentage of its participating employees. Following the Spin-off, the Company no longer participates in SEACOR Holdings’ self-insured health benefit plans;

•

certain officers and employees of the Company received compensation through participation in SEACOR Holdings’ share award plans. The Company paid SEACOR Holdings for the fair value of its employees’ share awards. Pursuant to the Employee Matters Agreement with SEACOR Holdings, participating Company personnel vested in all outstanding SEACOR Holdings share awards upon the Spin-off and received SEACOR Marine restricted stock from the Spin-off distribution in connection with outstanding SEACOR Holdings restricted stock held. As a consequence, the Company paid SEACOR Holdings $9.4 million upon completion of the Spin-off, including $2.7 million for the distribution of 120,693 shares of SEACOR Marine restricted stock (see Note 16), which is being amortized over the participants’ remaining original vesting periods, and $6.7 million on the accelerated vesting of SEACOR Holdings share awards, which was immediately recognized. In addition, the Company recognized and paid share award expense of $1.7 million through the date of the Spin-off; and

•

prior to the Spin-off, SEACOR Holdings provided certain administrative support services to the Company under a shared services arrangement, including but not limited to payroll processing, information systems support, benefit plan management, cash disbursement support and treasury management. The Company was charged for its share of actual costs incurred generally based on volume processed or units supported.

Transactions regarding OSV Partners. Charles Fabrikant (Non-Executive Chairman of SEACOR Marine), John Gellert (President, Chief Executive Officer and Director of SEACOR Marine), Jesús Llorca (Executive Vice President and Chief Financial Officer of SEACOR Marine), other members of the Company’s management and board of directors and other unaffiliated individuals indirectly invested in OSV Partners by purchasing interests from three unaffiliated limited partners of OSV Partners who wished to dispose of their interests. During 2018, OSV Partners (i) raised $7.5 million of cash: $5 million in the form of second lien debt and $2.5 million in the form of class A preferred interests and (ii) obtained commitments from the limited partners of OSV Partners for an additional $2.5 million in the form of class a preferred interest. On December 18, 2019, the general partner of OSV Partners called these remaining commitments. As of December 31, 2019, limited liability companies controlled by management and directors of the Company had invested $1.5 million, or 3.9%, in the limited partner interests; $0.3 million, or 5.0%, in preferred interests; $0.2 million, or 3.9%, in the form of second lien debt; and $0.2 million, or 3.9%, in the class A preferred interests of OSV Partners. As of December 31, 2019, the investments of Messrs. Fabrikant, Gellert and Llorca in such limited liability companies were $0.3 million, $0.4 million and $0.2 million, respectively, representing 39.6% of such limited liability companies’ membership interests. The general partner of OSV Partners is a joint venture managed by the Company and an unaffiliated third-party. The Company owns 30.4% in the limited partner interests, 38.6% in the preferred interests, 43.0% of the second lien debt, and 43.0% in the class A preferred interest of OSV Partners. The Company agreed to abate to zero the management fees it charges to OSV Partners through December 31, 2020.

Transactions regarding Windcat Workboats. On January 25, 2019, Seabulk Overseas, a wholly-owned subsidiary of SEACOR Marine, acquired a 6.25% minority interest in Windcat Workboats that it did not previously own upon the exercise of a put option by one of the two minority owners, each of whom is a member (or an affiliate of a member) of management of Windcat Workboats, pursuant to the terms of a certain Subscription and Shareholders Agreement, as amended, for consideration of £1.6 ($2.0 million). On March 15, 2019, Seabulk Overseas acquired the other 6.25% minority interest in Windcat Workboats that it did not previously own for consideration of 50,000 shares of Common Stock and €1.2 million (approximately $1.4 million) in cash. The two acquisitions resulted in Seabulk Overseas owning 100% of Windcat Workboats, a consolidated subsidiary which owns and operates the Company’s CTV that are primarily used to move personnel and supplies in Europe’s offshore wind markets.

Transactions with Carlyle. On December 1, 2015, the Company issued $175.0 million aggregate principal amount of its Convertible Notes to investment funds managed and controlled by Carlyle. Interest on the Convertible Notes is payable semi-annually on June 15 and December 15 of each year, commencing June 15, 2016 (see Note 8).

Pursuant to the note purchase agreement for the Convertible Notes and the Investment Agreement, the Company must use reasonable best efforts, subject to its directors’ fiduciary duties, to cause a person designated by Carlyle to be appointed as a director on the Board, if Carlyle, solely as a result of the conversion of the Convertible Notes, collectively owns, continues to own, or would (upon conversion) own 10.0% or more of the Company’s outstanding shares of Common Stock. During 2017, Ferris Hussein served on the Board as the director designated by Carlyle until his resignation on April 17, 2018. Carlyle has not exercised this right subsequent to Mr. Hussein’s resignation but retains the right to appoint a Board member. Mr. Hussein has been designated by Carlyle to observe meetings of the Board pursuant to Carlyle’s observer rights under the Convertible Notes. This observation right will terminate at the time Carlyle owns less than $50.0 million in aggregate principal amount of the Convertible Notes or a combination of the Convertible Notes and our Common Stock representing less than 5.0% of the Company’s Common Stock outstanding on a fully diluted basis, assuming the conversion of all of the Convertible Notes and Warrants to purchase Common Stock held by Carlyle.

In April 2018, the Company entered into the following Exchange and other transactions with Carlyle pursuant to which:

•

the Company exchanged $50.0 million in principal amount of the Convertible Notes for Common Stock (or warrants to purchase an equivalent number of shares of Common Stock at an exercise price of $0.01 per share) at an exchange rate of 37.73 per $1,000 principal amount of the Notes (equivalent to an exchange price of $26.50) for a total of approximately 1.9 million shares of Common Stock including Common Stock issuable upon exercise of the Exchange Warrants (the “Exchange”);

•

the Company and Carlyle amended the $125.0 million in principal amount of Convertible Notes that remains outstanding after the Exchange to (i) increase the interest rate from 3.75% per annum to 4.25% per annum and (ii) extend the maturity of the Convertible Notes by 12 months to December 1, 2023; and

•

Carlyle purchased 750,000 shares of Common Stock in a private placement whereby the Company issued an aggregate of 2,168,586 shares of Common Stock and warrants to purchase 674,164 shares of Common Stock at an exercise price of $0.01 per share in a private placement exempt from registration under the Securities Act (the “PIPE Issuance”) for aggregate consideration of $15.0 million.

Transactions with CME. Mr. Alfredo Miguel Bejos, who was elected as a director at the Company’s 2019 annual meeting, currently serves as President and Chief Executive Officer of CME. The Company entered into the following transactions with CME in 2018:

•

On April 26, 2018, CME purchased 325,836 shares of Common Stock and 674,164 warrants to purchase the Company’s Common Stock in the PIPE Issuance for aggregate consideration of $20.0 million.

•

On December 20, 2018, MEXMAR Offshore, a joint venture that is 49.0% owned by a subsidiary of the Company and 51.0% owned by a subsidiary of CME, acquired UP Offshore. UP Offshore was acquired for nominal consideration. In connection with the acquisition, UP Offshore’s existing debt was refinanced with $95.0 million of new indebtedness composed of (i) a $70.0 million six-year debt facility provided by UP Offshore’s existing lenders that is non-recourse to the Company, CME or any of their respective subsidiaries, (ii) a $15.0 million loan from MexMar, a joint venture between CME and the Company, to fund capital expenditures on two vessels and (iii) a $10.0 million loan from MEXMAR Offshore to fund working capital requirements funded by an approximate $5.0 million capital contribution to MEXMAR Offshore by each of the Company and CME.

The Company also participates in a variety of other joint ventures with CME, including MexMar, SMLLC and OVH. During 2018, the Company earned charter revenue of $16.5 million and management fees of $300,000 from MexMar. These agreements with MexMar were negotiated at arms-length in the ordinary course of business. In addition, in 2018:

•

The Company created a new subsidiary, SMLLC and contributed the Seacor Marlin supply vessel into SMLLC. On September 13, 2018, the Company sold 51.0% of SMLLC to MEXMAR Offshore, a wholly-owned subsidiary of MexMar, for $8.0 million in cash. The Seacor Marlin supply vessel was pledged as collateral under the MexMar credit facility, for which the Company receives an annual collateral fee.

•

The Company received a return of a capital advance from MexMar of $9.8 million.

In 2019, the Company sold an FSV to OVH for $2.4 million through a seller’s finance agreement.

Other Transactions. JMG GST LLC, an entity managed by Mr. John Gellert, President, Chief Executive Officer and director of SEACOR Marine, purchased $1,000,000, or 50,000 shares, of Common Stock in the PIPE Issuance.

Leases

12 Months Ended

Dec. 31, 2019

Leases [Abstract]

Leases

LEASES

On February 25, 2016, the FASB issued a comprehensive new leasing standard, ASC 842, Leases, meant to improve transparency and comparability among companies by requiring lessees to recognize a lease liability and a corresponding lease asset for virtually all lease contracts. It also requires additional disclosures about leasing arrangements. The Company adopted the standard on January 1, 2019 and applied the transition provisions of the standard with recognition of a cumulative-effect adjustment to the opening balance of retained earnings. The adoption of the standard had a material impact on the Company’s consolidated financial position, results of operations and cash flows. The adjustment to the Company’s balance sheet on January 1, 2019 included the addition of $33.7 million of right-of-use assets, $31.9 million in lease liability, and a cumulative-effect adjustment to the opening balance of retained earnings of $1.7 million for certain of its equipment, office and land leases. In addition, unamortized deferred gains for four vessels previously accounted for under sale-leaseback arrangements of $8.7 million, ($11.0 million deferred gains net of $2.3 million deferred taxes), were fully recognized as an adjustment to the opening balance of retained earnings

As of December 31, 2019, the Company leases in three AHTS vessels, two liftboats, one FSV and certain facilities and other equipment. The leases typically contain purchase and renewal options or rights of first refusal with respect to the sale or lease of the equipment. As of December 31, 2019, the remaining lease terms of the vessels have remaining durations from 11 to 23 months. The lease terms of the other equipment range in duration from one to 324 months.

As of December 31, 2019, future minimum payments for operating leases for the years ended December 31 were as follows (in thousands):

2020	$	15,355
2021		7,128
2022		668
2023		621
2024		696
Years subsequent to 2024		4,437
		28,905
Interest component		(3,984	)
		24,921
Current portion of long-term operating lease liabilities		15,099
Long-term operating lease liabilities	$	9,822

For the year ended December 31, 2019, the components of lease expense were as follows (in thousands):

	2019
Operating lease expense	$	13,639
Short-term lease expense (lease duration of twelve months or less at lease commencement)		2,519
	$	16,158

For the year ended December 31, 2019, other information related to operating leases were as follows (in thousands except weighted average data):

	2019
Operating cash flows from operating leases	$	19,339
Right-of-use assets obtained for operating lease liabilities	$	35,246
Weighted average remaining lease term, in years		4.7
Weighted average discount rate		4.1	%

The Company performed an impairment analysis and determined that some of the leased offshore support vessels are impaired due to an operating or cash flow loss currently and in the forecasted future. The Company recorded impairment losses of $5.3 million for one such lease for the year ended December 31, 2019 and $6.8 million for three such leases for the year ended December 31, 2018. A liability was recorded to reflect the amount of future lease payments, expenses required to maintain the vessels, and expenses required to return the vessels to their owners at the end of the lease term, offset by unamortized deferred gain on the sale-leaseback of the vessels.

Stockholders' Equity

12 Months Ended

Dec. 31, 2019

Equity [Abstract]

Stockholders' Equity

13.	STOCKHOLDERS' EQUITY

On January 1, 2019, the Company adopted ASC 842 regarding the recording of lease on the balance sheet. This adoption resulted in an increase of $10.4 million, net of tax, to the Company’s opening retained earnings for the current period.

On January 9, 2019, certain indirect wholly owned subsidiaries of SEACOR Marine acquired three FSVs in exchange for the private placement of 603,872 shares of its Common Stock to domestic U.S. holders affiliated with the McCall family of Louisiana. The value of the vessels and the Common Stock was $7.8 million based on the closing price of a share of Common Stock on the NYSE on the day of the exchange. The Common Stock was issued in reliance upon the exemption from registration provided by Section 4(a)(2) of the Securities Act. The Company has operated the acquired vessels for the past ten years under a revenue sharing pooling agreement that included four of its owned FSVs of similar specification. In accordance with its terms, this pooling agreement was terminated.

On January 25, 2019, Seabulk Overseas Transport, Inc., a wholly owned subsidiary of SEACOR Marine (“Seabulk Overseas”), acquired a 6.25% minority interest in Windcat Workboats that it did not previously own upon the exercise of certain put options by one of the two minority owners pursuant to the terms of a subscription and shareholders agreement, as amended (the “Subscription and Shareholders Agreement”), in exchange for consideration of £1.6 million (approximately $2.0 million) in cash. The Company acquired the other 6.25% minority interest in Windcat Workboats that the Company did not already own on March 15, 2019 in exchange for consideration of 50,000 shares of Common Stock and €1.2 million (approximately $1.4 million) in cash. The Common Stock was issued in a private placement in reliance upon the exemption from registration provided by Section 4(a)(2) of the Securities Act. The two acquisitions resulted in Seabulk Overseas owning (and SEACOR Marine indirectly owning) 100% of Windcat Workboats.

On January 1, 2018, the Company adopted a new accounting standard issued by the FASB on October 24, 2016, which requires companies to account for the income tax effects of intercompany sales and transfers of assets other than inventory. The impact of the adoption of the new standard resulted in a reduction of $12.1 million to the Company’s opening retained earnings.

On February 8, 2018, the Company formed FGH, a joint venture between the Company and MOI. In accordance with the terms of the Joint Venture Contribution and Formation Agreement, the Company and MOI contributed certain liftboat vessels and other related assets to the joint venture and assumed certain operating liabilities and indebtedness associated with the liftboat vessels and related assets. The transaction consolidated 15 liftboat vessels operated by the Company and six liftboat vessels previously operated by MOI. FGUSA, a wholly-owned subsidiary of FGH, paid $15.0 million of MOI’s debtor-in-possession obligations and entered into a $131.1 million credit agreement comprised of the FGUSA Term Loan and the FGUSA Revolving Loan Facility. The Company performed a fair market valuation of the debt resulting in a debt discount of $9.5 million on the FGUSA Term Loan and $0.5 million debt discount on the FGUSA Revolving Loan Facility, which will be amortized over the life of the FGUSA Credit Facility. The debt discount on the FGUSA Revolving Loan Facility resulted in an adjustment of $0.4 million to stockholder’s equity.

On March 26, 2018, the Company issued 103,213 shares of Common Stock to an accredited investor for a total of $1.8 million in gross proceeds pursuant to a private placement in reliance on the exemption from registration set forth in Section 4(a)(2) of the Securities Act.

On April 26, 2018, the Company closed the PIPE Private Placement resulting in aggregate gross proceeds of $56.9 million. The PIPE Private Placement included the issuance of the PIPE Shares and the PIPE Warrants. The PIPE Shares and PIPE Warrants were issued in reliance upon the exemption from registration provided by Section 4(a)(2) of the Securities Act.

On May 2, 2018, the Company and Carlyle entered into the Exchange pursuant to which Carlyle exchanged $50.0 million in principal amount of the Convertible Senior Notes for the Carlyle Warrants. The Carlyle Warrants were issued in reliance upon the exemption from registration provided by Section 4(a)(2) of the Securities Act.

On May 31, 2018 and June 8, 2018, there were 250,693 and 38,857 warrants exercised, respectively for a penny per share. There were 108 shares of Common Stock held in treasury in exchange for the payment of the penny per warrant on certain of the warrants converted.

Consolidated Statements of Loss - USD ($) $ in Thousands	12 Months Ended
Consolidated Statements of Loss - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Statement [Abstract]
Operating Revenues	$ 201,492	$ 203,567	$ 123,421
Costs and Expenses:
Operating	123,725	132,274	104,821
Administrative and general	44,726	46,454	49,865
Lease expense	16,158	13,239	14,449
Depreciation and amortization	64,012	68,841	60,307
Costs and expenses	248,621	260,808	229,442
Losses on Asset Dispositions and Impairments, Net	(5,397)	(11,268)	(23,623)
Operating Loss	(52,526)	(68,509)	(129,644)
Other Income (Expense):
Interest income	1,445	1,222	1,797
Interest expense	(30,056)	(27,404)	(16,044)
SEACOR Holdings management fees			(3,208)
SEACOR Holdings guarantee fees	(108)	(29)	(201)
Loss on Debt Extinguishment		(638)
Marketable security gains (losses), net			10,931
Derivative gains, net	71	2,854	20,256
Foreign currency losses, net	(1,661)	(1,397)	(1,671)
Other, net	(1)	677	(6)
Nonoperating income expense	(30,310)	(24,715)	11,854
Loss from Continuing Operations Before Tax Benefit and Equity in Earnings (Losses) of 50% or Less Owned Companies	(82,836)	(93,224)	(117,790)
Income Tax Expense (Benefit):
Current	4,955	9,383	(13,404)
Deferred	(12,867)	(22,737)	(61,006)
Income Tax Expense (Benefit)	(7,912)	(13,354)	(74,410)
Loss Before Equity in (Losses) Earnings of 50% or Less Owned Companies	(74,924)	(79,870)	(43,380)
Equity in (Losses) Earnings of 50% or Less Owned Companies, Net of Tax	(14,304)	(3,552)	3,851
Loss from Continuing Operations	(89,228)	(83,422)	(39,529)
(Loss) Income on Discontinued Operations, Net of Tax (including loss on disposal of $9,106)	(9,467)	1,370	989
Net Loss	(98,695)	(82,052)	(38,540)
Net Loss attributable to Noncontrolling Interests in Subsidiaries	(5,858)	(4,444)	(5,639)
Net Loss attributable to SEACOR Marine Holdings Inc.	$ (92,837)	$ (77,608)	$ (32,901)
Basic and Diluted Income (Loss) Per Common Share and Warrants of SEACOR Marine Holdings Inc.
Continuing operations	$ (3.55)	$ (3.77)	$ (1.93)
Discontinued operations	(0.40)	0.07	0.06
Basic and Diluted Income (Loss) Per Common Share and Warrants	$ (3.95)	$ (3.70)	$ (1.87)
Weighted Average Common Shares and Warrants Outstanding:
Basic and diluted shares	23,513,925	20,926,307	17,601,244

Nature of Operations and Accounting Policies - Schedule of Property and Equipment Useful Life (Details)	12 Months Ended
	Dec. 31, 2019
Crew Transfer Vessels
Property Plant And Equipment [Line Items]
Estimated useful life (Year)	10 years
All Other Offshore Support Vessels
Property Plant And Equipment [Line Items]
Estimated useful life (Year)	20 years

Major Customers and Segment Information - Schedule of Segment Reporting Information, by Segment (Parenthetical) (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
Assets, Total	$ 1,009,193	$ 1,102,938
Assets held for sale		41,502	$ 37,054
Corporate, Non-Segment
Segment Reporting Information [Line Items]
Assets, Total	$ 145,232	$ 153,151	$ 169,346

Construction Reserve Funds - Schedule of Construction Reserve Fund Transactions (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Restricted Cash And Investments [Abstract]
Withdrawals	$ (15,168)	$ (17,300)	$ (39,163)
Deposits			6,315
Construction reserve fund, net	$ (15,168)	$ (17,300)	$ (32,848)

Equipment Acquisitions and Dispositions - Schedule of Vessel Acquired and Disposed (Details)

12 Months Ended

Dec. 31, 2019

Dec. 31, 2018

Dec. 31, 2017

^[1]

^[2]

^[3]

^[4]

Fast Support Vessels

^[1]

Offshore Support Vessels, Supply

^[2]

^[3]

^[1]

Offshore Support Vessels, Liftboats

^[2]

^[4]

^[2]

^[3]

^[4]

Crew Transfer Vessels

^[1]

Anchor Handling Towing Supply

^[3]

Derivative Instruments And Hedging Activities Disclosure [Abstract]

^[2]

^[3]

[1]	Excludes three FSVs purchased from managed entities, one crew transfer vessel sold upon completion and one ERRV purchased from a joint venture.
[2]	Excludes the sale of (i) 18 ERRV vessels from the sale of the Company North Sea Standby Safety business, (ii) one crew transfer vessel to the joint venture FRS Windcat Offshore Logistics, (iii) one FSV to the joint venture OVH, (iv) one FSV to a third party with the Company continuing to manage the vessel, (v) one ERRV from discontinued operations and (vi) six vessels that were previously removed from service (five AHTS vessels and one specialty vessel).
[3]	Excludes three ERRVs from discontinued operations
[4]	Excludes one ERRV from discontinued operations.

Derivative Instruments and Hedging Strategies

12 Months Ended

Dec. 31, 2019

Derivative Instruments and Hedging Strategies

10.	DERIVATIVE INSTRUMENTS AND HEDGING STRATEGIES

		2019				2018
	Balance Sheet Classification	Derivative Asset		Derivative Liability		Derivative Asset		Derivative Liability
Derivatives designated as hedging instruments:
Interest rate swap agreements (cash flow hedges)	Current	$	—	$	3,009	$	—	$	1,659
			—		3,009		—		1,659
Derivatives not designated as hedging instruments:
Conversion option liability on Convertible Senior Notes	Long-Term		—		5,205		—		5,276
		$	—	$	8,214	$	—	$	6,935

Fair Value Hedges. From time to time, the Company may designate certain of its foreign currency exchange contracts as fair value hedges in respect of capital commitments denominated in foreign currencies. By entering into these foreign currency exchange contracts, the Company may fix a portion of its capital commitments denominated in foreign currencies in U.S. dollars to protect against currency fluctuations. During the year ended December 31, 2017, the Company recognized gains of $0.1 million on these contracts which were recognized to the corresponding hedged equipment included in construction in progress in the accompanying consolidated balance sheets.

Cash Flow Hedges. The Company and certain of its 50% or less owned companies have interest rate swap agreements designated as cash flow hedges at their inception. By entering into these interest rate swap agreements, the Company and its 50% or less owned companies have converted the variable LIBOR or EURIBOR component of certain of their outstanding borrowings to a fixed interest rate. The Company recognized losses on derivative instruments designated as cash flow hedges of $1.3 million for the year ended December 31, 2019, gains of $1.6 million for the year ended December 31, 2018 and losses of $0.2 million for the year ended December 31, 2017 as a component of other comprehensive loss. As of December 31, 2019, the interest rate swaps held by the Company and certain of the Company’s 50% or less owned companies were as follows:

•

Windcat Workboats had two interest rate swap agreements maturing in 2021 that call for the Company to pay a fixed rate of interest of (0.03%) plus margin on the aggregate notional value of €15.0 million ($16.8 million) and receive a variable interest rate based on EURIBOR on the aggregate notional value;

•

SEACOR Marine Foreign Holdings had an interest rate swap agreement maturing in 2023 that calls for SMFH to pay a fixed rate of interest of 3.32% plus margin on the amortized notional value of $8.8 million and receive a variable interest rate based on LIBOR on the amortized notional value;

•

SEACOR Marine Foreign Holdings had an interest rate swap agreement maturing in 2023 that calls for SMFH to pay a fixed rate of interest of 3.195% plus margin on the amortized notional value of $48.6 million and receive a variable interest rate based on LIBOR on the amortized notional value; and

•

SEACOR 88/888 had an interest rate swap agreement maturing in 2023 that calls for Seacor 88/888 to pay a fixed rate of interest of 3.175% plus margin on the amortized notional value of $5.5 million and receive a variable interest rate based on LIBOR on the amortized notional value.

Derivative Instruments. The Company utilizes derivative instruments to manage the volatility of cash flows due to fluctuating interest rates. All derivative instruments not qualifying for the normal purchase and normal sale exception are recorded on the balance sheets at fair value. The treatment of the periodic changes in fair value will depend on whether the derivative is designated and effective as a hedge for accounting purposes.

If a derivative qualifies for hedge accounting and is designated as a cash flow hedge, the effective portion of the change in fair value of the derivative is deferred in Accumulated Other Comprehensive Income (“AOCI”), a component of owners’ equity, and reclassified to earnings when the forecasted transaction occurs. Cash flows from a derivative instrument designated as a hedge are classified in the same category as the cash flows from the item being hedged. As such, we include the cash flows from interest rate derivative instruments in interest expense.

If a derivative does not qualify as a hedge or is not designated as a hedge, the gain or loss resulting from the change in fair value on the derivative is recognized currently in earnings as a component of other income (expense).

We formally document all relationships between hedging instruments and hedged items, as well as its risk management objectives and strategy for undertaking the hedge. This documentation includes the specific identification of the hedging instrument and the hedged item, the nature of the risk being hedged and the manner in which the hedging instrument’s effectiveness will be assessed. At the inception of the hedge, and on an ongoing basis, we assess whether the derivatives used in hedging transactions are highly effective in offsetting changes in cash flows of hedged items.

The relationship between the hedging instrument and the hedged item must be highly effective in achieving the offset of changes in cash flows attributable to the hedged risk both at the inception of the contract and on an ongoing basis. We measure hedge ineffectiveness on a quarterly basis and reclassify any ineffective portion of the gain or loss related to the change in fair value to earnings in the current period.

We will discontinue hedge accounting on a prospective basis when a hedge instrument is terminated or ceases to be highly effective. Gains and losses deferred in AOCI related to cash flow hedges for which hedge accounting has been discontinued remain deferred until the forecasted transaction occurs. If it is no longer probable that a hedged forecasted transaction will occur, deferred gains or losses on the hedging instrument are reclassified to earnings immediately.

For balance sheet classification purposes, we analyze the fair values of the derivative instruments on a contract by contract basis and report the related fair values and any related collateral by counterparty on a gross basis. Realized and unrealized gains and losses on derivatives designated as cash flow hedges that are entered into by the Company’s 50% or less owned companies are also reported as a component of the Company’s other comprehensive loss in proportion to the Company’s ownership percentage, with reclassifications and ineffective portions being included in equity in earnings (losses) of 50% or less owned companies, net of tax, in the accompanying consolidated statements of loss.

The fair value of our derivative instruments, depending on the type of instrument, was determined by the use of present value methods or standard option valuation models with assumptions about commodity prices based on those observed in underlying markets. The estimated fair value of our derivative instruments was a net liability of $8.2 million as of December 31, 2019. The estimated fair value is net of an adjustment for credit risk based on the default probabilities by year as indicated by market quotes for the counterparties’ credit default swap rates. The credit risk adjustment was immaterial for all periods presented.

The following tables reflect amounts recorded in Other Comprehensive Income (“OCI”) and amounts reclassified from OCI to revenue and expense for the periods indicated:

	Gain (Loss) Recognized in OCI on Derivatives (Effective Portion)
Derivatives in Cash Flow Hedging Relationships	2019			2018			2017
Interest rate swap contracts	$	(1,901	)	$	(1,939	)	$	214
Joint venture interest rate swap contracts		(645	)		(76	)		389

	Gain (Loss) Reclassified from OCI into Income (Effective Portion)
Location of Gain	2019			2018			2017
Interest expense	$	552		$	31			118

Our consolidated earnings are also affected by the use of the mark-to-market method of accounting for derivative instruments that do not qualify for hedge accounting or that have not been designated as hedges. The changes in fair value of these instruments are recorded on the balance sheet and through earnings rather than being deferred until the anticipated transaction settles. The use of mark-to-market accounting for financial instruments can cause non-cash earnings volatility due to changes in the underlying commodity price indices.

Other Derivative Instruments. The Company recognized gains (losses) on derivative instruments not designated as hedging instruments for the years ended December 31 as follows (in thousands):

	Derivative gains (losses), net
	2019		2018		2017
Conversion option liability on Convertible Senior Notes	$	71	$	1,556	$	20,422
Interest rate swap agreements		—		1,298		46
Forward currency exchange, option and future contracts		—		—		(212	)
	$	71	$	2,854	$	20,256

The conversion option liability relates to the bifurcated embedded conversion option in the Convertible Senior Notes (See Note 8).

The Company and certain of the Company’s 50% or less owned companies have entered into interest rate swap agreements for the general purpose of providing protection against increases in interest rates, which might lead to higher interest costs. As of December 31, 2019, the interest rate swaps held by the Company or its 50% or less owned companies were as follows:

•

OSV Partners had two interest rate swap agreements with maturities in 2020 that call for OSV Partners to pay a fixed rate of interest ranging from 1.89% to 2.27% plus margin on the aggregate amortized notional value of $22.8 million and receive a variable interest rate based on LIBOR on the aggregate amortized notional value.

•

MexMar had five interest rate swap agreements with maturities in 2023 that call for MexMar to pay a fixed rate of interest ranging from 1.71% to 2.10% plus margin on the aggregate amortized notional value of $83.2 million and receive a variable interest rate based on LIBOR on the aggregate amortized notional value.

Prior to 2017, the Company held positions in publicly traded equity options that convey the right or obligation to engage in a future transaction on the underlying equity security or index. The Company’s investment in equity options primarily included positions in energy related businesses. These contracts were typically entered into to mitigate the risk of changes in market value of marketable security positions that the Company was either about to acquire, had acquired or was about to dispose.

The Company enters and settles forward currency exchange, option and future contracts with respect to various foreign currencies. These contracts enable the Company to buy currencies in the future at fixed exchange rates, which could offset possible consequences of changes in currency exchange rates with respect to the Company’s business conducted outside of the U.S. The Company generally does not enter into contracts with forward settlement dates beyond twelve to eighteen months. There are no outstanding contracts at December 31, 2019.

Nature of Operations and Accounting Policies - Schedule of Deferred Gain Activity (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Sale-leaseback and Financed Equipment Sales
Balance at beginning of year	$ 11,026	$ 23,553	$ 32,035
Amortization of deferred gains		(8,037)	(8,118)
Reclass of gain to Retained Earnings	(11,026)
Recognition of deferred gains included in losses on asset dispositions and impairments, net		(4,490)
Other			(364)
Balance at end of year		11,026	23,553
Vessel Sales to Fifty Percent or Less Owned Subsidiaries
Balance at beginning of year	793	1,453	1,875
Amortization of deferred gains		(25)
Other	$ (793)	(635)	(422)
Balance at end of year		$ 793	$ 1,453

Major Customers and Segment Information

12 Months Ended

Dec. 31, 2019

Notes To Financial Statements [Abstract]

Major Customers and Segment Information

19.	MAJOR CUSTOMERS AND SEGMENT INFORMATION

During the year ended December 31, 2019, Seacor Marine Arabia LLC was responsible for $30.8 million or 15% ($20.3 million or 10% from Zamil Offshore and $10.5 million or 5% from Saudi Aramco) of the Company’s total consolidated operating revenues from continuing operations. During the year ended December 31, 2018, Seacor Marine Arabia LLC was responsible for $21.4 million or 10% ($12.2 million or 6% from Zamil Offshore and $9.2 million or 4% from Saudi Aramco) of the Company’s total consolidated operating revenues from continuing operations. During the year ended December 31, 2017, Seacor Marine Arabia LLC was responsible for $16.0 million or 13% ($4.5 million or 4% from Zamil Offshore and $11.2 million or 9% from Saudi Aramco) of the Company’s total consolidated operating revenues from continuing operations.

During the years ended December 31, 2019, 2018 and 2017, the ten largest customers of the Company accounted for approximately 44%, 49%, and 58%, respectively, of the Company’s operating revenues from continuing operations. The loss of one or more of these customers could have a material adverse effect on the Company’s results of operations and cash flows.

For the years ended December 31, 2019, 2018 and 2017, approximately 78%, 36%, and 82%, respectively, of the Company’s operating revenues and $(12.8) million, $(3.0) million, and $2.0 million, respectively, of equity in (losses) earnings from 50% or less owned companies, net of tax, were derived from its continuing foreign operations.

The Company’s offshore support vessels are highly mobile and regularly and routinely move between countries within a geographic region of the world. In addition, these vessels may be redeployed among the geographic regions, subject to flag restrictions, as changes in market conditions dictate. Because of this asset mobility, operating revenues and long-lived assets in any one country and capital expenditures for long-lived assets and gains or losses on asset dispositions and impairments in any one geographic region are not considered meaningful.

	United States (primarily Gulf of Mexico)			Africa (primarily West Africa)			Middle East and Asia			Latin America			Europe Continuing Operations			Total
For the year ended December 31, 2019
Operating Revenues:
Time charter	$	38,955		$	44,160		$	54,312		$	11,460		$	33,414		$	182,301
Bareboat charter		1,562			—			—			3,569			—			5,131
Other		3,806			1,461			1,669			1,390			5,734			14,060
		44,323			45,621			55,981			16,419			39,148			201,492
Direct Costs and Expenses:
Operating:
Personnel		17,491			13,833			16,698			4,459			13,031			65,512
Repairs and maintenance		7,583			4,701			7,182			1,348			3,855			24,669
Drydocking		4,594			490			600			161			3			5,848
Insurance and loss reserves		2,370			1,051			1,449			311			857			6,038
Fuel, lubes and supplies		2,936			3,471			2,904			1,056			960			11,327
Other		393			4,354			3,095			1,182			1,307			10,331
		35,367			27,900			31,928			8,517			20,013			123,725
Direct Vessel Profit	$	8,956		$	17,721		$	24,053		$	7,902		$	19,135			77,767
Other Costs and Expenses:
Operating:
Leased-in equipment	$	10,894		$	3,090		$	173		$	10		$	1,991			16,158
Administrative and general																	44,726
Depreciation and amortization	$	21,947		$	10,404		$	16,400		$	6,205		$	9,056			64,012
																	124,896
Losses on Asset Dispositions and Impairments, Net																	(5,397	)
Operating Loss																$	(52,526	)
As of December 31, 2019
Property and Equipment:
Historical cost	$	297,392		$	207,107		$	292,446		$	57,534		$	122,499		$	976,978
Accumulated depreciation		(157,514	)		(57,136	)		(73,039	)		(16,239	)		(55,034	)		(358,962	)
	$	139,878		$	149,971		$	219,407		$	41,295		$	67,465		$	618,016
Total Assets⁽¹⁾	$	224,229		$	161,915		$	250,890		$	116,736		$	109,874		$	863,644

(1)	Total assets exclude $145,232 thousand of corporate assets.

	United States (primarily Gulf of Mexico)			Africa (primarily West Africa)			Middle East and Asia			Latin America			Europe Continuing Operations			Total
For the year ended December 31, 2018
Operating Revenues:
Time charter	$	38,802		$	43,847		$	50,072		$	17,343		$	22,286		$	172,350
Bareboat charter		—			—			—			4,635			—			4,635
Other		14,762			7,661			(887	)		1,554			3,492			26,582
		53,564			51,508			49,185			23,532			25,778			203,567
Direct Costs and Expenses:
Operating:
Personnel		18,708			16,538			16,806			4,399			10,862			67,313
Repairs and maintenance		5,152			6,330			11,172			1,011			3,368			27,033
Drydocking		1,957			2,085			1,362			128			2,261			7,793
Insurance and loss reserves		2,922			1,096			1,371			495			459			6,343
Fuel, lubes and supplies		3,568			3,826			4,027			1,225			863			13,509
Other		393			4,313			3,980			1,130			467			10,283
		32,700			34,188			38,718			8,388			18,280			132,274
Direct Vessel Profit	$	20,864		$	17,320		$	10,467		$	15,144		$	7,498			71,293
Other Costs and Expenses:
Operating:
Leased-in equipment	$	8,240		$	4,281		$	224		$	5		$	489			13,239
Administrative and general																	46,454
Depreciation and amortization	$	23,227		$	10,453		$	18,762		$	7,908		$	8,491			68,841
																	128,534
Losses on Asset Dispositions and Impairments, Net																	(11,268	)
Operating Loss																$	(68,509	)
As of December 31, 2018
Property and Equipment:
Historical cost	$	432,336		$	184,361		$	306,897		$	124,177		$	68,812		$	1,116,583
Accumulated depreciation		(224,737	)		(55,206	)		(81,378	)		(57,002	)		(43,076	)		(461,399	)
	$	207,599		$	129,155		$	225,519		$	67,175		$	25,736		$	655,184
Total Assets⁽¹⁾	$	351,748		$	140,335		$	260,002		$	137,983		$	18,217		$	908,285

(1)	Total assets exclude $153,151 thousand of corporate assets, and $41,502 thousand of assets held-for-sale.

	United States (primarily Gulf of Mexico)			Africa (primarily West Africa)			Middle East and Asia			Latin America			Europe Continuing Operations			Total
For the year ended December 31, 2017
Operating Revenues:
Time charter	$	18,079		$	32,866		$	33,410		$	2,977		$	22,990		$	110,322
Bareboat charter		—			—			—			4,636			—			4,636
Other		4,217			1,080			474			552			2,140			8,463
		22,296			33,946			33,884			8,165			25,130			123,421
Direct Costs and Expenses:
Operating:
Personnel		15,621			13,419			16,883			809			7,881			54,613
Repairs and maintenance		3,594			5,957			9,037			274			2,462			21,324
Drydocking		1,828			2,180			968			—			—			4,976
Insurance and loss reserves		3,286			677			1,444			316			306			6,029
Fuel, lubes and supplies		1,485			2,815			3,727			223			496			8,746
Other		249			3,319			5,240			117			208			9,133
		26,063			28,367			37,299			1,739			11,353			104,821
Direct Vessel Profit (Loss)	$	(3,767	)	$	5,579		$	(3,415	)	$	6,426		$	13,777			18,600
Other Costs and Expenses:
Operating:
Leased-in equipment	$	8,709		$	4,317		$	1,092		$	5		$	326			14,449
Administrative and general																	49,865
Depreciation and amortization	$	22,060		$	9,280		$	17,724		$	3,608		$	7,635			60,307
																	124,621
Losses on Asset Dispositions and Impairments, Net																	(23,623	)
Operating Loss																$	(129,644	)
As of December 31, 2017
Property and Equipment:
Historical cost	$	410,475		$	192,600		$	326,378		$	72,484		$	56,367		$	1,058,304
Accumulated depreciation		(230,636	)		(57,228	)		(100,435	)		(37,281	)		(34,312	)		(459,892	)
	$	179,839		$	135,372		$	225,943		$	35,203		$	22,055		$	598,412
Total Assets⁽¹⁾	$	310,675		$	140,173		$	234,471		$	103,135		$	13,650		$	802,104

(1)	Total assets exclude $169,346 thousand of corporate assets, and $37,054 thousand of assets held-for-sale.

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash Flows from Continuing Operating Activities:
Net Loss	$ (98,334)	$ (83,422)	$ (39,529)
Adjustments to reconcile net loss to net cash (used in) provided by operating activities:
Depreciation and amortization	64,012	68,841	60,307
Deferred financing cost amortization	1,182	2,018	2,344
Amortization of deferred gains against charter expense		(8,037)	(8,118)
Debt discount and issue cost amortization, net	5,662	5,348	4,448
Director share awards	894	893	681
Restricted stock amortization	5,046	3,494	638
Restricted stock vesting	(577)	(88)	88
Bad debt (recoveries) expense	(404)	(880)	(1,283)
Losses on asset dispositions and impairments, net	5,397	11,268	23,623
Loss on sale of Emergency Response Rescue Vessels ("ERRV")	9,106
Gain from other sales		(428)
Marketable security (gains) losses, net			(10,931)
Proceeds from sale of marketable securities			51,877
Derivative gains, net	(71)	(2,854)	(20,256)
Cash settlements on derivative transactions, net	(536)	1,372	(512)
Foreign currency losses, net	1,661	1,397	1,671
Deferred	(12,867)	(22,737)	(61,006)
Equity in (earnings) losses of 50% or less owned companies, net of tax	14,304	3,552	(3,851)
Dividends received from 50% or less owned companies	2,073	1,724	2,642
Changes in operating assets and liabilities:
Decrease (increase) in receivables	8,487	(18,621)	31,263
Decrease in prepaid expenses and other assets	103	1,054	6,243
Decrease (Increase) in accounts payable, accrued expenses and other liabilities	4,309	(23,239)	(2,703)
Net cash provided by (used in) operating activities	9,447	(59,345)	37,636
Cash Flows from Investing Activities:
Purchases of property and equipment	(55,456)	(51,578)	(68,983)
Cash settlements on derivative transactions, net			(369)
Proceeds from disposition of property and equipment	56,183	20,140	10,701
Cash impact of sale of ERRV fleet	(5,140)
Sale of subsidiary to joint venture		8,017
Investments in and advances to 50% or less owned companies	(17,417)	(43,725)	(5,469)
Return of investments and advances from 50% or less owned companies	461	16,263	7,553
Net decrease in construction reserve funds	15,168	17,300	32,848
Principal payments on notes due from equity investees	22	116
Cash assumed on consolidation of 50% or less owned companies			1,943
Business acquisitions, net of cash acquired			(9,751)
Net cash provided by (used in) investing activities	21,211	(33,467)	(31,527)
Cash Flows from Financing Activities:
Payments on long-term debt	(23,974)	(49,405)	(11,926)
Proceeds from issuance of long-term debt, net of issue costs		62,017	6,545
Proceeds from exercise of stock options and warrants	1,424	833
Distribution of SEACOR Marine restricted stock to Company personnel by SEACOR Holdings			(2,656)
Issuance of stock		42,996
Issuance of warrants		12,809
Purchase of subsidiary shares from noncontrolling interests	(3,392)		(3,693)
Net cash provided by (used in) financing activities	(25,942)	69,250	(11,730)
Effects of Exchange Rate Changes on Cash, Cash Equivalents and Restricted Cash	(17,642)	(699)	(1,236)
Net (Decrease) in Cash, Cash Equivalents and Restricted Cash, Continuing Operations	(12,926)	(24,261)	(6,857)
Cash Flows from Discontinued Operations:
Operating Activities	5,992	6,320	(2,897)
Investing Activities	(5,569)	2,318	104
Effects of Exchange Rate Changes on Cash, Restricted Cash and Cash Equivalents	2,698	(75)	3,430
Net Decrease in Cash, Restricted Cash and Cash Equivalents on Discontinued Operations	3,121	8,563	637
Net Decrease in Cash, Cash Equivalents and Restricted Cash	(9,805)	(15,699)	(6,220)
Cash, Cash Equivalents and Restricted Cash, Beginning of Year	96,852	112,551	118,771
Cash, Cash Equivalents and Restricted Cash, End of Year	87,047	$ 96,852	$ 112,551
ERRV Fleet Business
Cash Flows from Investing Activities:
Proceeds from disposition of property and equipment	$ 27,390

Share Based Compensation - Schedule of Stock Option Transactions (Details) - $ / shares

12 Months Ended

Dec. 31, 2019

Dec. 31, 2018

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Non-Vested, shares (in shares)

805,566

Non-Vested, weight average grant price (in dollars per share)

$ 14.81

Granted, shares (in shares)

230,503

258,491

Granted, weight average grant price (in dollars per share)

$ 8.73

Exercise of options (in shares)

113,750

66,625

Exercised (in dollars per share)

$ 13.98

Forfeited, shares (in shares)

8,750

Forfeited, weight average grant price (in dollars per share)

$ 20.93

Non-Vested, shares (in shares)

913,569

805,566

Non-Vested, weight average grant price (in dollars per share)

$ 14.85

$ 14.81

Exercisable, shares (in shares)

^[1]

408,075

Exercisable, weight average grant price (in dollars per share)

$ 14.69

[1]	The weighted average remaining contractual term is 8.23 years.

Transformation, Facility Restructuring and Severance Charges

12 Months Ended

Dec. 31, 2019

Restructuring And Related Activities [Abstract]

Transformation, Facility Restructuring and Severance Charges

2.	TRANSFORMATION, FACILITY RESTRUCTURING AND SEVERANCE CHARGES

Due to the highly competitive nature of the Company’s business and the continuing losses incurred over the last few years, the Company continues to reduce its overall cost structure and workforce to better align the Company with current activity levels. The ongoing transformation plan, which began in the third quarter of 2019 and is expected to extend through the second quarter of 2020 (the “Transformation Plan”), includes a workforce reduction, organization restructuring, facility consolidations and other cost reduction measures and efficiency initiatives across the Company’s geographic regions. The Transformation Plan was initiated to reduce the Company’s overall cost structure and workforce to better align with current activity levels of oil and gas exploration and production.

In connection with the Transformation Plan, the Company recognized one-time restructuring charges of $3.3 million and $0.4 million during the third and fourth quarter of 2019. Year-to-date restructuring charges recorded were $3.7 million, which included severance charges of $3.4 million and other restructuring charges of $0.3 million. Other restructuring charges included contract termination costs, relocation and other associated costs.

The components of restructuring charges year ended December 31, 2019, were as follows (in thousands):

	United States (primarily Gulf of Mexico)		Africa (primarily West Africa)		Middle East and Asia		Latin America		Europe (primarily North Sea)		Total
Transformation Plan Charges
Severance	$	2,995	$	—	$	184	$	—	$	200	$	3,379
Other		307		—		31		1		—		339
Total	$	3,302	$	—	$	215	$	1	$	200	$	3,718

The severance and other restructuring charges gave rise to certain liabilities, the components of which are summarized in the following table (in thousands), and largely relate to liabilities accrued as part of the 2019 Transformation Plan that will be paid pursuant to the respective arrangements and statutory requirements.

	United States (primarily Gulf of Mexico)		Africa (primarily West Africa)		Middle East and Asia		Latin America		Europe (primarily North Sea)		Total
Transformation Plan
Severance Liability	$	216	$	—	$	—	$	—	$	33	$	249
Other Liability		—		—		—		—		—		—
Total Liability	$	216	$	—	$	—	$	—	$	33	$	249

The following table is a summary of the cumulative restructuring and reorganization cost incurred in operating charges and the estimated remaining restructuring and reorganization costs to be incurred as of December 31, 2019 (in thousands).

	2019		2020		Total
One-time termination benefits	$	3,379	$	2,014	$	5,393
Professional and other		339		—		339
Total restructuring and reorganization costs incurred and to be incurred	$	3,718	$	2,014	$	5,732

Nature of Operations and Accounting Policies - Summary of Property and Equipment (Details) - USD ($)
$ in Thousands

Dec. 31, 2019

Dec. 31, 2018

Dec. 31, 2017

$ 976,978

^[1]

$ 1,116,583

^[1]

$ 1,058,304

(358,962)

(461,399)

(459,892)

Offshore Support Vessels, Anchor Handling Towing Supply

618,016

655,184

$ 598,412

^[1],[2]

94,078

197,344

^[2]

(73,095)

(168,731)

^[2]

20,983

28,613

Fast Support Vessels

^[1],[3]

388,460

404,310

^[3]

(101,295)

(98,580)

Offshore Support Vessels, Supply

^[3]

287,165

305,730

^[1]

44,958

64,284

(8,471)

(37,202)

Offshore Support Vessels, Specialty

36,487

27,082

^[1]

14,805

25,683

(10,466)

(20,433)

Offshore Support Vessels, Liftboats

4,339

5,250

^[1]

327,028

329,473

(93,166)

(71,887)

233,862

257,586

Crew Transfer Vessels

^[1]

82,645

73,589

(54,358)

(46,614)

General Machinery and Spares

28,287

26,975

^[1]

7,650

8,457

(7,648)

(8,390)

Property, Plant and Equipment, Other Types

^[1],[4]

17,354

13,443

^[4]

(10,463)

(9,562)

Fair Value, Inputs, Level 1

^[4]

$ 6,891

$ 3,881

[1]	Includes property and equipment acquired in business acquisitions at acquisition date fair value, and net of the impact of recognized impairment charges.
[2]	Anchor Handling Towing Supply (“AHTS”)
[3]	Fast support vessels (“FSVs”)
[4]	Includes land, buildings, leasehold improvements, vehicles and other property and equipment.

Fair Value Measurements - Schedule of Fair Value of Assets and Liabilities Measured on Recurring Basis (Details) - Fair Value, Measurements, Recurring - USD ($)
$ in Thousands

Dec. 31, 2019

Dec. 31, 2018

Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]

Construction reserve funds

$ 12,893

$ 28,221

Fair Value, Inputs, Level 2

Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]

Derivative instruments (included in other receivables)

419

Derivative Liability

3,009

1,659

Fair Value, Inputs, Level 3

Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]

Conversion Option Liability on Convertible Senior Notes

^[1]

$ 5,205

$ 5,276

[1]	For the year ended December 31, 2019, the Company recognized a $0.1 million gain in the fair market valuation of the Convertible Senior Notes, as valued by an independent third-party

Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2019

Fair Value Disclosures [Abstract]

Schedule of Fair Value of Assets and Liabilities Measured on Recurring Basis

The Company’s financial assets and liabilities as of December 31 that are measured at fair value on a recurring basis were as follows (in thousands):

	Level 1		Level 2		Level 3⁽¹⁾
2019
ASSETS
Construction reserve funds	$	12,893	$	—	$	—
LIABILITIES
Derivative instruments (included in other current liabilities)		—		3,009		—
Conversion Option Liability on Convertible Senior Notes		—		—		5,205
2018
ASSETS
Derivative instruments (included in other receivables)	$	—	$	419	$	—
Construction reserve funds		28,221		—		—
LIABILITIES
Derivative instruments (included in other current liabilities)		—		1,659		—
Conversion Option Liability on Convertible Senior Notes		—		—		5,276

(1)	For the year ended December 31, 2019, the Company recognized a $0.1 million gain in the fair market valuation of the Convertible Senior Notes, as valued by an independent third-party.

Schedule of Estimated Fair Values of Financial Assets and Liabilities

The estimated fair value of the Company’s other financial assets and liabilities as of December 31 were as follows (in thousands):

			Estimated Fair Value
	Carrying Amount		Level 1		Level 2		Level 3
2019
ASSETS
Cash, cash equivalents and restricted cash	$	87,047	$	87,047	$	—	$	—
Investments, at cost, in 50% or less owned companies (included in other assets)		132	see below
LIABILITIES
Long-term debt, including current portion		398,053		—		380,815		—
2018
ASSETS
Cash, cash equivalents and restricted cash	$	93,254	$	93,254	$	—	$	—
Investments, at cost, in 50% or less owned companies (included in other assets)		132	see below
LIABILITIES
Long-term debt, including current portion		404,666		—		388,949		—

Schedule of Other Assets and Liabilities Measured at Fair Value

The Company’s non-financial assets and liabilities that were measured at fair value during the years ended December 31 were as follows (in thousands):

	Level 1		Level 2		Level 3
2019
ASSETS
Property and equipment:
AHTS	$	—	$	520	$	—
FSV		—		1,858		—
2018
ASSETS
Property and equipment:
AHTS	$	—	$	2,000	$	—
Liftboats		—		—		134,775
Specialty		—		4,500		—

Supplemental Information for Statements of Cash Flows

12 Months Ended

Dec. 31, 2019

Supplemental Cash Flow Elements [Abstract]

Supplemental Information for Statements of Cash Flows

20.	SUPPLEMENTAL INFORMATION FOR STATEMENTS OF CASH FLOWS

Supplemental information for the years ended December 31 was as follows (in thousands):

	2019		2018			2017
Income taxes (paid) refunded, net	$	1,999	$	(316	)	$	33,773
Interest paid, excluding capitalized interest		22,452		21,031			9,216

Share Based Compensation - Schedule of Equity Incentive Plan Transactions (Details) (Parenthetical)	Dec. 31, 2019 shares
Performance Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares outstanding	91,600

Nature of Operations and Accounting Policies - Schedule Of Cash, Cash Equivalents And Restricted Cash (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Nature Of Operation And Accounting Policies [Abstract]
Cash	$ 83,943	$ 91,597
Restricted cash	3,104	1,657
Total	$ 87,047	$ 93,254

Commitment and Contingencies

12 Months Ended

Dec. 31, 2019

Commitments And Contingencies Disclosure [Abstract]

Commitments and Contingencies

18.	COMMITMENTS AND CONTINGENCIES

As of December 31, 2019, the Company had capital commitments of $35.9 million for four PSVs, one CTV and other equipment, to be delivered in 2020. The Company has indefinitely deferred an additional $30.2 million of orders with respect to three FSVs.

In 2015, the Brazilian Federal Revenue Office issued a tax-deficiency notice to Seabulk Offshore do Brasil Ltda (“Seabulk Offshore do Brasil”), an indirectly wholly owned subsidiary of SEACOR Marine, with respect to certain profit participation contribution (“PIS”) and social security financing contribution (“COFINS”) requirements alleged to be due from Seabulk Offshore do Brasil (“Deficiency Notice”). In February 2015, Company deposited with the relevant Brazilian court an amount equal to USD $1.2 million and appealed the Deficiency Notice on the basis that such contributions were not applicable in the circumstances of a 70%/30% cost allocation structure. The case was remitted to the second instance and is currently awaiting trial. Recently, a local Brazilian law was enacted that supports the Company’s position that such contribution requirements are not applicable, but it is uncertain whether such law will be taken into consideration with respect to administrative proceedings commenced prior to the enactment of the law. Accordingly, the success of Seabulk Offshore do Brasil in the administrative proceedings cannot be assured. The potential range of levies arising from the Deficiency Notice is R$12.8 million - R$17.5 million (USD $3.2 million – USD $4.3 million based on the exchange rate as of December 31, 2019).

In the normal course of its business, the Company becomes involved in various other litigation matters including, among other things, claims by third-parties for alleged property damages and personal injuries. Management has used estimates in determining the Company’s potential exposure to these matters and has recorded reserves in its financial statements related thereto where appropriate. It is possible that a change in the Company’s estimates of that exposure could occur, but the Company does not expect such changes in estimated costs could have a material adverse effect on the Company’s business, financial position, results of operations, cash flows and growth prospects.

The Company has $2.0 million available under its Windcat Workboats credit facilities.

Fair Value Measurements - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Impairment charges	$ 12.0	$ 14.6	$ 27.5

Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Net Loss	$ (98,695)	$ (82,052)	$ (38,540)
Other Comprehensive Loss:
Foreign currency translation (losses) gains, net	20,157	(2,365)	4,654
Reclassification of foreign currency translation losses to foreign currency losses, net			0
Derivative (losses) gains on cash flow hedges	(1,901)	(1,939)	214
Other comprehensive income	18,163	(4,349)	5,375
Income tax (expense) benefit	173	(46)	(6,256)
Other comprehensive income, net	18,336	(4,395)	(881)
Comprehensive Loss	(80,359)	(86,447)	(39,421)
Comprehensive Loss attributable to Noncontrolling Interests in Subsidiaries	(5,858)	(4,544)	(5,364)
Comprehensive Loss attributable to SEACOR Marine Holdings Inc.	(74,501)	(81,903)	(34,057)
Interest Expense
Other Comprehensive Loss:
Reclassification of derivative gains (losses) on cash flow hedges	552	31	118
Equity Method Investments
Other Comprehensive Loss:
Reclassification of derivative gains (losses) on cash flow hedges	$ (645)	$ (76)	$ 389

Construction Reserve Funds (Tables)

12 Months Ended

Dec. 31, 2019

Restricted Cash And Investments [Abstract]

Schedule of Construction Reserve Fund Transactions

Construction reserve fund transactions for the years ended December 31 were as follows (in thousands):

	2019			2018			2017
Withdrawals	$	(15,168	)	$	(17,300	)	$	(39,163	)
Deposits		—			—			6,315
	$	(15,168	)	$	(17,300	)	$	(32,848	)

Related Party Transactions - Additional Information (Details)
$ / shares in Units, € in Millions, £ in Millions

1 Months Ended

3 Months Ended

12 Months Ended

Mar. 15, 2019

USD ($)

Mar. 15, 2019

GBP (£)

Mar. 15, 2019

EUR (€)

Jan. 25, 2019

USD ($)

Jan. 25, 2019

GBP (£)

Jan. 09, 2019

Dec. 20, 2018

USD ($)

Sep. 28, 2018

USD ($)

Sep. 13, 2018

USD ($)

May 02, 2018

USD ($)

$ / shares

Apr. 26, 2018

USD ($)

$ / shares

Mar. 26, 2018

Dec. 01, 2015

USD ($)

Apr. 30, 2018

USD ($)

$ / shares

Dec. 31, 2019

USD ($)

Sep. 30, 2019

USD ($)

Jun. 30, 2019

USD ($)

Mar. 31, 2019

USD ($)

Dec. 31, 2018

USD ($)

Sep. 30, 2018

USD ($)

Jun. 30, 2018

USD ($)

Mar. 31, 2018

USD ($)

Dec. 31, 2019

USD ($)

Dec. 31, 2018

USD ($)

Dec. 31, 2017

USD ($)

Dec. 28, 2018

Related Party Transaction, Rate

0.50%

Interest Expense, Related Party

$ 200,000

$ 300,000

11,214,000

Percentage of reimbursement of severance and restructuring cost

50.00%

49.00%

103,213

$ 6,596,000

42,996,000

$ 95,000,000

$ 10,000,000

Sale of subsidiary to joint venture

$ 49,070,000

$ 54,700,000

$ 52,812,000

$ 44,910,000

$ 58,897,000

$ 58,169,000

$ 47,871,000

$ 38,630,000

201,492,000

203,567,000

123,421,000

$ 8,017,000

Mexmar Offshore International

Noncontrolling interest, ownership percentage by noncontrolling owners

49.00%

51.00%

Offshore Vessel Holdings

Noncontrolling interest, ownership percentage by noncontrolling owners

51.00%

10,000,000

Financing agreement

$ 2,400,000

Private Placement

603,872

56,900,000

750,000

Warrants Issued in Private Placement

$ 56,855,000

$ 15,000,000

Class of warrant or right, exercise price of warrants or rights | $ / shares

$ 0.01

Class of warrant or right, outstanding | shares

2,168,586

Class of warrant or right, number of securities called by warrants or rights | shares

674,164

Convertible Senior Notes 3.75%

Convertible debt, total

$ 125,000,000

$ 175,000,000

$ 125,000,000

Debt instrument, convertible, conversion ratio

23.26

Debt instrument, face amount

1,000

$ 1,000

Debt instrument, interest rate

4.25%

3.75%

4.25%

Lender Non Recourse

Debt instrument, convertible, terms of conversion feature

$ 70,000,000

Carlyle Group

Convertible debt, total

$ 175,000,000

Interest rate term

Interest on the Convertible Notes is payable semi-annually on June 15 and December 15 of each year, commencing June 15, 2016

Carlyle has not exercised this right subsequent to Mr. Hussein’s resignation but retains the right to appoint a Board member. Mr. Hussein has been designated by Carlyle to observe meetings of the Board pursuant to Carlyle’s observer rights under the Convertible Notes. This observation right will terminate at the time Carlyle owns less than $50.0 million in aggregate principal amount of the Convertible Notes or a combination of the Convertible Notes and our Common Stock representing less than 5.0% of the Company’s Common Stock outstanding on a fully diluted basis, assuming the conversion of all of the Convertible Notes and Warrants to purchase Common Stock held by Carlyle.

Carlyle Group | Convertible Senior Notes Converted to Warrants

Debt conversion, original debt, amount

$ 50,000,000

Class of warrant or right, exercise price of warrants or rights | $ / shares

$ 0.01

Debt instrument, convertible, conversion ratio

37.73

Debt instrument, face amount

$ 1,000

Debt instrument, convertible, conversion price | $ / shares

$ 26.50

Debt conversion, converted instrument, shares issued | shares

1,886,792

1,900,000

Windcat Workboats Facilities | Seabulk Overseas

Business acquisition, percentage of voting interests acquired

6.25%

100.00%

Ownership Percentage

100.00%

Business combination, consideration transferred, total

$ 1,400,000

£ 1.2

€ 1.2

$ 2,000,000

£ 1.6

Business acquisition, exchange for consideration | shares

50,000

OSV Partners

Revenue from related parties

$ 0

600,000

Proceeds from Sale of Interest in Partnership Unit

7,500,000

30.40%

OSV Partners | Limited Partner | Llorca

$ 5,000,000

2,300,000

OSV Partners | General Partner

$ 400,000

38.60%

OSV Partners | Second Lien Debt

6,000,000

Proceeds from issuance of debt

5,000,000

OSV Partners | Series A Preferred Stock

43.00%

Proceeds from Issuance of Redeemable Preferred Stock

2,500,000

Proceeds From issuance of additional redeemable preferred stock

2,500,000

43.00%

CME

5,000,000

CME | Private Placement

325,836

CME | Warrants Issued in Private Placement

$ 20,000,000

Class of warrant or right, number of securities called by warrants or rights | shares

674,164

MexMar

Revenue from related parties

$ 300,000

300,000

49.00%

15,000,000

Capital distributions from equity investees

16,500,000

$ 9,800,000

$ 0

9,800,000

MEXMAR Offshore

^[1]

49.00%

10,000,000

$ 5,000,000

SEACOR Marlin LLC

Equity method investment, ownership, percent sold

49.00%

51.00%

Sale of subsidiary to joint venture

$ 8,000,000

JMG GST LLC

50,000

Adjustments to Additional Paid in Capital, Other

$ 1,000,000

Restricted Stock

$ 2,700,000

Stock issued during period, shares, restricted stock award, gross | shares

120,693

Share Distribution

$ 6,700,000

Transition Services Agreement

$ 600,000

4,500,000

3,300,000

Maximum

Percentage of convertible notes converted into common stock

50.00%

Maximum | Carlyle Group

Convertible debt, total

$ 50,000,000

5.0

Maximum | Transition Services Agreement

$ 6,300,000

Minimum

Percentage of convertible notes converted into common stock

20.00%

Minimum | Carlyle Group

10.0

Restructuring Charges

$ 6,000,000

Restructuring Charges | Maximum

3,000,000

Severance Liability

$ 700,000

SEACOR Holdings

Revenue from related parties

$ 100,000

Guarantor Obligations, Maximum Exposure, Undiscounted

$ 22,800,000

$ 40,600,000

22,800,000

$ 40,600,000

9,400,000

Allocated share-based compensation expense, total

1,700,000

Officer | OSV Partners | Limited Partner | Fabrikant

Officer | OSV Partners | Limited Partner | Gellert

300,000

Officer | OSV Partners | Limited Partner | Fabrikant And Gellert

$ 200,000

Officer | OSV Partners | Second Lien Debt | General Partner

39.60%

General Partners' Capital Account, Total

3.90%

$ 200,000

Officer | OSV Partners | Series A Preferred Stock | General Partner

General Partners' Capital Account, Total

3.90%

$ 200,000

Officer | Maximum | OSV Partners

Officer | Maximum | OSV Partners | Limited Partner

$ 1,500,000

Officer | Maximum | OSV Partners | General Partner

3.90%

General Partners' Capital Account, Total

5.00%

$ 300,000

[1]	This joint venture holds the investment in UP Offshore

Quarterly Financial Information (Unaudited)

12 Months Ended

Dec. 31, 2019

Quarterly Financial Information Disclosure [Abstract]

Quarterly Financial Information

23.	QUARTERLY FINANCIAL INFORMATION (UNAUDITED)

Selected financial information for interim quarterly periods is presented below (in thousands, except share data). Earnings (loss) per common share of SEACOR Marine Holdings Inc. are computed independently for each of the quarters presented and the sum of the quarterly earnings per share may not necessarily equal the total for the year.

	Three Months Ended
	Dec. 31,			Sept. 30,			June 30,			March 31,
2019
Operating Revenues	$	49,070		$	54,700		$	52,812		$	44,910
Operating Loss		(10,497	)		(3,355	)		(17,640	)		(21,034	)
Net (Loss) Income:
Continuing Operations		(19,176	)		(10,341	)		(31,438	)		(28,273	)
Discontinued Operations		(2,742	)		(7,899	)		1,174			—
	$	(21,918	)	$	(18,240	)	$	(30,264	)	$	(28,273	)
Net Loss attributable to SEACOR Marine Holdings Inc:	$	(20,455	)	$	(18,444	)	$	(28,389	)	$	(25,549	)
Basic and Diluted Loss Per Common Share of SEACOR Marine Holdings Inc.
Continuing Operations	$	(0.74	)	$	(0.49	)	$	(1.31	)	$	(1.16	)
Discontinued Operations	$	(0.12	)	$	(0.29	)	$	0.10		$	0.05
	$	(0.86	)	$	(0.78	)	$	(1.21	)	$	(1.11	)
2018
Operating Revenues	$	58,897		$	58,169		$	47,871		$	38,630
Operating Loss		(11,253	)		(12,207	)		(20,842	)		(24,206	)
Net (Loss) Income:
Continuing Operations		(7,780	)		(17,706	)		(26,505	)		(31,430	)
Discontinued Operations		(189	)		1,940			(124	)		(258	)
	$	(7,969	)	$	(15,766	)	$	(26,629	)	$	(31,688	)
Net Loss attributable to SEACOR Marine Holdings Inc:	$	(7,794	)	$	(15,957	)	$	(25,024	)	$	(28,833	)
Basic and Diluted Loss Per Common Share of SEACOR Marine Holdings Inc.
Continuing Operations	$	(0.39	)	$	(0.85	)	$	(1.18	)	$	(1.63	)
Discontinued Operations	$	0.04		$	0.14		$	(0.01	)	$	(0.01	)
	$	(0.35	)	$	(0.71	)	$	(1.19	)	$	(1.64	)

Share Based Compensation - Schedule of Equity Incentive Plan Transactions (Details) - shares

12 Months Ended

Dec. 31, 2019

Dec. 31, 2018

Share Based Compensation Arrangement By Share Based Payment Award [Line Items]

Outstanding as of the beginning of year (in shares)

805,566

613,700

Granted - 2017 Plan (in shares)

230,503

258,491

Exercised (in shares)

113,750

66,625

Forfeited (in shares)

8,750

Outstanding as of the end of year (in shares)

913,569

805,566

Director Stock Awards

Share Based Compensation Arrangement By Share Based Payment Award [Line Items]

Granted (in shares)

30,197

19,285

Restricted Stock

Share Based Compensation Arrangement By Share Based Payment Award [Line Items]

Outstanding as of the beginning of year (in shares)

192,346

121,693

Granted (in shares)

245,400

^[1]

120,600

Vested (in shares)

131,937

49,947

Forfeited (in shares)

2,200

Outstanding as of the end of year (in shares)

303,609

192,346

[1]	Excludes 91,600 grants of performance-based stock units that are not considered outstanding until such time that they become probable to vest.

Income Taxes - Components of Income Tax Expense (Benefit) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Federal, current	$ (6)	$ 5,987	$ (16,705)
State, current	(78)	3	(42)
Foreign, current	5,039	3,393	3,343
Current income tax expense	4,955	9,383	(13,404)
Federal, deferred	(12,594)	(21,466)	(60,750)
State, deferred	(224)	(1,404)	(172)
Foreign, deferred	(49)	133	(84)
Deferred income tax benefit	(12,867)	(22,737)	(61,006)
Income Tax Expense (Benefit)	$ (7,912)	$ (13,354)	$ (74,410)

Long-term Debt (Tables)

12 Months Ended

Dec. 31, 2019

Debt Disclosure [Abstract]

Schedule of Long-term Debt Obligations

The Company’s long-term debt obligations as of December 31 were as follows (in thousands):

	2019			2018
Convertible Senior Notes	$	125,000		$	125,000
SEACOR Marine Foreign Holdings Loan Facility		113,750			126,750
Falcon Global USA Term Loan Facility		102,349			109,099
Sea-Cat Crewzer III Term Loan Facility		24,128			25,989
Windcat Workboats Facilities		24,730			24,850
Falcon Global USA Revolver		15,000			15,000
SEACOR 88/888 Term Loan		11,000			11,000
SEACOR Alps		10,534			—
BNDES Equipment Construction Finance Notes		3,332			5,284
		429,823			442,972
Portion due within one year		(17,802	)		(16,812	)
Debt discount		(26,343	)		(32,005	)
Issue costs		(5,427	)		(6,301	)
	$	380,251		$	387,854

Schedule of Long-term Debt Maturities

The Company’s contractual long-term debt maturities for the years ended December 31 were as follows (in thousands):

2020	$	17,802
2021		51,789
2022		26,007
2023		231,674
2024		90,800
Years subsequent to 2024		11,752
	$	429,823

- Definition

Tabular disclosure of long-debt instruments or arrangements, including identification, terms, features, collateral requirements and other information necessary to a fair presentation. These are debt arrangements that originally required repayment more than twelve months after issuance or greater than the normal operating cycle of the entity, if longer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28541-108399

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21506-112644

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(e),(f))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28551-108399

Reference 6: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
-Section 50
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-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21521-112644

Reference 7: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
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-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21538-112644

Reference 8: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
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-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=75038535&loc=d3e64711-112823

Reference 9: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

Reference 10: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21475-112644

+ Details

Leases - Summary of Other Information Related to Operating Leases (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($)
Leases [Abstract]
Operating cash flows from operating leases	$ 19,339
Right-of-use assets obtained for operating lease liabilities	$ 35,246
Weighted average remaining lease term, in years	4 years 8 months 12 days
Weighted average discount rate	4.10%

Fair Value Measurements - Schedule of Other Assets and Liabilities Measured at Fair Value (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Fair Value, Inputs, Level 2 \| Anchor Handling Towing Supply
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Property and equipment	$ 520	$ 2,000
Fair Value, Inputs, Level 2 \| Fast Support Vessels
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Property and equipment	$ 1,858
Fair Value, Inputs, Level 2 \| Offshore Support Vessels, Specialty
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Property and equipment		4,500
Fair Value, Inputs, Level 3 \| Liftboats
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Property and equipment		$ 134,775

Transformation, Facility Restructuring and Severance Charges - Schedule of Components of Restructuring Charges (Details) - Transformation Plan - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Dec. 31, 2019
Restructuring Cost And Reserve [Line Items]
Severance			$ 3,379
Other			339
Total	$ 400	$ 3,300	3,718
UNITED STATES
Restructuring Cost And Reserve [Line Items]
Severance			2,995
Other			307
Total			3,302
Middle East and Asia
Restructuring Cost And Reserve [Line Items]
Severance			184
Other			31
Total			215
Latin America
Restructuring Cost And Reserve [Line Items]
Other			1
Total			1
Europe
Restructuring Cost And Reserve [Line Items]
Severance			200
Total			$ 200

Warrants - Additional Information (Details) - USD ($)							1 Months Ended	12 Months Ended
Warrants - Additional Information (Details) - USD ($)	Jun. 14, 2019	May 28, 2019	Jun. 08, 2018	May 31, 2018	May 02, 2018	Apr. 26, 2018	Apr. 30, 2018	Dec. 31, 2019	Dec. 31, 2018
Class Of Warrant Or Right [Line Items]
Stock issued during period, value, new issues								$ 6,596,000	$ 42,996,000
Class of warrant or right, exercised during period			38,857	250,693
Carlyle Group \| Convertible Senior Notes Converted to Warrants
Class Of Warrant Or Right [Line Items]
Class of warrant or right, exercise price of warrants or rights					$ 0.01		$ 0.01
Debt conversion, original debt, amount					$ 50,000,000		$ 50,000,000
Warrants Issued in Private Placement
Class Of Warrant Or Right [Line Items]
Class of warrant or right, outstanding						2,168,586	2,168,586
Class of warrant or right, number of securities called by warrants or rights						674,164	674,164
Class of warrant or right, exercise price of warrants or rights						$ 0.01	$ 0.01
PIPE Warrants
Class Of Warrant Or Right [Line Items]
Class of warrant or right, exercise price of warrants or rights						$ 0.01
Warrants and rights outstanding, term						25 years
Exchange Warrants
Class Of Warrant Or Right [Line Items]
Class of warrant or right, outstanding								1,826,966	2,271,406
Class of warrant or right, exercise price of warrants or rights					$ 0.01
Warrants and rights outstanding, term					25 years
Class of warrant or right, exercised during period	64,440	380,000	38,857	250,693
Number of shares withheld in an exercise to purchase warrants as payment for the exercise	49
Exchange Warrants \| Carlyle Group
Class Of Warrant Or Right [Line Items]
Class of warrant or right, number of securities called by warrants or rights					1,886,292
Private Placement
Class Of Warrant Or Right [Line Items]
Stock issued during period, value, new issues						$ 56,855,000	$ 15,000,000

Transformation, Facility Restructuring and Severance Charges (Tables)

12 Months Ended

Dec. 31, 2019

Restructuring And Related Activities [Abstract]

Schedule of Components of Restructuring Charges

The components of restructuring charges year ended December 31, 2019, were as follows (in thousands):

	United States (primarily Gulf of Mexico)		Africa (primarily West Africa)		Middle East and Asia		Latin America		Europe (primarily North Sea)		Total
Transformation Plan Charges
Severance	$	2,995	$	—	$	184	$	—	$	200	$	3,379
Other		307		—		31		1		—		339
Total	$	3,302	$	—	$	215	$	1	$	200	$	3,718

Schedule of Severance and Other Restructuring Charges

	United States (primarily Gulf of Mexico)		Africa (primarily West Africa)		Middle East and Asia		Latin America		Europe (primarily North Sea)		Total
Transformation Plan
Severance Liability	$	216	$	—	$	—	$	—	$	33	$	249
Other Liability		—		—		—		—		—		—
Total Liability	$	216	$	—	$	—	$	—	$	33	$	249

Schedule of Cumulative Restructuring and Reorganization Cost Incurred to Date, Estimated Remaining and to be Incurred

	2019		2020		Total
One-time termination benefits	$	3,379	$	2,014	$	5,393
Professional and other		339		—		339
Total restructuring and reorganization costs incurred and to be incurred	$	3,718	$	2,014	$	5,732

Supplemental Information for Statements of Cash Flows (Tables)

12 Months Ended

Dec. 31, 2019

Supplemental Cash Flow Elements [Abstract]

Schedule of Supplemental Information

Supplemental information for the years ended December 31 was as follows (in thousands):

	2019		2018			2017
Income taxes (paid) refunded, net	$	1,999	$	(316	)	$	33,773
Interest paid, excluding capitalized interest		22,452		21,031			9,216

Nature of Operations and Accounting Policies - Schedule of Accumulated Other Comprehensive Loss (Details) - USD ($)
$ in Thousands

12 Months Ended

Dec. 31, 2019

Dec. 31, 2018

Dec. 31, 2017

Accumulated Other Comprehensive Income Loss [Line Items]

$ 554,935

$ 523,166

18,163

(4,349)

$ 5,375

(173)

6,256

Accumulated Foreign Currency Adjustment Attributable to Parent

478,924

554,935

523,166

Accumulated Other Comprehensive Income Loss [Line Items]

(15,472)

(13,195)

(11,413)

20,157

(2,277)

4,397

^[1]

(6,179)

Accumulated Loss, Net, Cash Flow Hedge, Parent

4,685

(15,472)

(13,195)

Accumulated Other Comprehensive Income Loss [Line Items]

(1,316)

702

(1,994)

(1,972)

703

173

(46)

(77)

^[1]

AOCI Attributable to Parent

(3,137)

(1,316)

702

Accumulated Other Comprehensive Income Loss [Line Items]

(16,788)

(12,493)

(11,337)

18,163

(4,249)

5,100

173

(46)

(6,256)

^[1]

Accumulated Foreign Currency Adjustment Attributable to Noncontrolling Interest

1,548

(16,788)

(12,493)

Accumulated Other Comprehensive Income Loss [Line Items]

(1,445)

(1,357)

(1,614)

(88)

257

Accumulated Gain (Loss), Net, Cash Flow Hedge, Noncontrolling Interest

(1,445)

(1,357)

Accumulated Other Comprehensive Income Loss [Line Items]

(11)

(17)

(12)

AOCI Attributable to Noncontrolling Interest

(11)

Accumulated Other Comprehensive Income Loss [Line Items]

(11,620)

(7,225)

(6,344)

18,163

(4,349)

5,375

173

(46)

(6,256)

^[1]