Investments, at Equity, and Advances to 50% or Less Owned Companies - Schedule of Equity Investments (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2021	Dec. 31, 2020		Dec. 31, 2019	Jul. 23, 2021	Jun. 01, 2021	Dec. 20, 2018
Schedule Of Investments [Line Items]
Ownership percentage						50.00%	50.00%	49.00%
Investments at equity		$ 71,727	$ 75,308
Current assets		108,778	178,696
Current liabilities		84,665	131,804
Operating Revenues		170,941	141,837		$ 174,453
Operating (Loss) Income		33,137	(83,346)		(100,070)
Net Income (Loss)		$ 33,137	$ (82,982)		(98,695)
Minimum [Member]
Schedule Of Investments [Line Items]
Ownership percentage		20.00%
Maximum
Schedule Of Investments [Line Items]
Ownership percentage		50.00%	50.00%
MexMar
Schedule Of Investments [Line Items]
Ownership percentage		49.00%
Investments at equity		$ 59,940	$ 50,037
OSV Partners
Schedule Of Investments [Line Items]
Ownership percentage	[1]	30.40%
Investments at equity		$ 17,280	9,094	[1]
SEACOR Marlin LLC
Schedule Of Investments [Line Items]
Ownership percentage		49.00%
Investments at equity		$ 6,958	7,979
MEXMAR Offshore
Schedule Of Investments [Line Items]
Ownership percentage	[2]	49.00%
Investments at equity	[2]		1,960
Offshore Vessel Holdings
Schedule Of Investments [Line Items]
Ownership percentage		49.00%
Investments at equity		$ 1,847	2,388
Other Offshore Marine Services Joint Ventures
Schedule Of Investments [Line Items]
Investments at equity		$ 2,982	3,850
Other Offshore Marine Services Joint Ventures | Minimum [Member]
Schedule Of Investments [Line Items]
Ownership percentage		20.00%
Other Offshore Marine Services Joint Ventures | Maximum
Schedule Of Investments [Line Items]
Ownership percentage		50.00%
All Other Excluding MexMar, Falcon Global, Sea-Cat Crewzer and Sea-Cat Crewzer II
Schedule Of Investments [Line Items]
Operating and administrative		$ 139,313	142,228		116,517
Depreciation		23,524	27,044		27,412
Costs and expenses		162,837	169,272		143,929
Loss on Asset Dispositions and Impairments, Net					(166)
Operating (Loss) Income		(6,258)	(8,491)		(7,405)
Net Income (Loss)		41,798	(18,229)		(36,816)
All Other Excluding MexMar, Falcon Global, Sea-Cat Crewzer and Sea-Cat Crewzer II | Equity Method Investment, Nonconsolidated Investee or Group of Investees
Schedule Of Investments [Line Items]
Current assets		119,559	109,687
Noncurrent assets		181,712	259,424
Current liabilities		93,304	109,074
Noncurrent liabilities		65,902	115,626
Operating Revenues		$ 156,579	$ 160,781		$ 136,690

[1] ^{The Company owned 66.7% of the General Partner and 29.7% of the limited partnership interest of OSV Partners I. On December 31, 2021, the Company purchased the remaining shares in this joint venture that it did not own and consolidated the net assets of OSV Partners. See details below as well as “Note 3. Business Acquisitions”.}

[2] ^{This joint venture holds the investment in UP Offshore. The Company received a cash distribution in excess of its investment in MEXMOR Offshore during 2021. The distribution exceeded the investment value by $9.4 million and this amount was recognized as gain from return of investments in 50% or less owned companies. On December 9, 2021, the Company sold their ownership in this joint venture to the majority shareholder. See details below.}