Unaudited Condensed Consolidated Statements of Income (Loss) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Income Statement [Abstract]
Operating Revenues	$ 45,591	$ 36,512
Costs and Expenses:
Operating	39,496	26,307
Administrative and general	9,924	8,611
Lease expense	1,060	1,078
Depreciation and amortization	14,371	14,798
Costs and expenses	64,851	50,794
Gains (Losses) on Asset Dispositions and Impairments, Net	2,139	(2,273)
Operating Loss	(17,121)	(16,555)
Other Income (Expense):
Interest income	29	986
Interest expense	(6,627)	(8,018)
SEACOR Holdings guarantee fees		(7)
Derivative (losses) gains, net	(34)	355
Foreign currency gains (losses), net	821	(466)
Nonoperating income expense	(5,811)	(7,150)
Loss from Continuing Operations Before Income Tax Benefit and Equity in Earnings of 50% or Less Owned Companies	(22,932)	(23,705)
Income Tax Benefit	(2,421)	(2,688)
Loss from Continuing Operations Before Equity in Earnings of 50% or Less Owned Companies	(20,511)	(21,017)
Equity in Earnings Gains of 50% or Less Owned Companies	5,674	4,103
Loss from Continuing Operations	(14,837)	(16,914)
Income on Discontinued Operations, Net of Tax (see Note 12)		22,925
Net (Loss) Income	(14,837)	6,011
Net (Loss) Income Attributable to SEACOR Marine Holdings Inc.	$ (14,837)	$ 6,011
Net Loss Per Common Share from Continuing Operations:
Basic	$ (0.56)	$ (0.67)
Diluted	(0.56)	(0.67)
Net Earnings Per Share from Discontinued Operations:
Basic		0.91
Diluted		0.91
Net (Loss) Earnings per Share:
Basic	(0.56)	0.24
Diluted	$ (0.56)	$ 0.24
Weighted Average Common Stock and Warrants Outstanding:
Basic	26,379,293	25,304,661
Diluted	26,379,293	25,304,661