Condensed Consolidated Statements of Comprehensive Income (Loss) Statement - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Net Loss	$ (29,085)	$ (50,933)	$ (18,429)	$ (71,457)
Foreign currency translation gains (losses)	1,058	(4,468)	1,722	(6,336)
Derivative losses on cash flow hedges	(380)	(1,838)	(389)	(3,668)
Other	9	4	16	9
Other Comprehensive Income (Loss), before Tax	609	(5,208)	1,459	(8,687)
Income tax benefit (expense)	(190)	1,640	(454)	2,794
Other Comprehensive Income (Loss), Net of Tax	419	(3,568)	1,005	(5,893)
Comprehensive Loss	(28,666)	(54,501)	(17,424)	(77,350)
Comprehensive Income attributable to Noncontrolling Interests in Subsidiaries	3,788	3,704	10,457	10,185
Comprehensive Loss attributable to SEACOR Holdings Inc.	(32,454)	(58,205)	(27,881)	(87,535)
Interest Expense [Member]
Reclassification of derivative losses on cash flow hedges to equity in earnings (losses) of 50% or less owned companies	21	0	33	0
Equity Method Investments [Member]
Reclassification of derivative losses on cash flow hedges to equity in earnings (losses) of 50% or less owned companies	$ 81	$ (1,102)	$ (109)	$ (1,326)