Consolidated Statements Of Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Statement [Abstract]
Operating Revenues	$ 830,985	$ 1,054,736	$ 1,319,394
Costs and Expenses:
Operating	597,813	748,605	909,372
Administrative and general	138,581	156,611	164,938
Depreciation and amortization	124,933	125,987	131,819
Total costs and expenses	861,327	1,031,203	1,206,129
Gains (Losses) on Asset Dispositions and Impairments, Net	(142,205)	(2,408)	51,978
Operating Income (Loss)	(172,547)	21,125	165,243
Other Income (Expense):
Interest income	19,339	20,020	19,662
Interest expense	(49,726)	(43,297)	(43,632)
Debt extinguishment gains (losses), net	5,184	(28,497)	0
Marketable security gains (losses), net	(32,199)	(74)	28,760
Derivative losses, net	(10,225)	(2,096)	(3,902)
Foreign currency losses, net	(1,868)	(4,752)	(6,335)
Other, net	(20,206)	6,773	3,439
Nonoperating Income (Expense)	(89,701)	(51,923)	(2,008)
Income (Loss) Before Income Tax Expense (Benefit) and Equity in Earnings (Losses) of 50% or Less Owned Companies	(262,248)	(30,798)	163,235
Income Tax Expense (Benefit):
Current	1,894	26,568	72,261
Deferred	(95,724)	(37,930)	(17,064)
Income Tax Expense (Benefit)	(93,830)	(11,362)	55,197
Income (Loss) Before Equity in Earnings (Losses) of 50% or Less Owned Companies	(168,418)	(19,436)	108,038
Equity in Earnings (Losses) of 50% or Less Owned Companies	(27,354)	(40,414)	16,309
Net Income (Loss)	(195,772)	(59,850)	124,347
Net Income Attributable to Noncontrolling Interests in Subsidiaries	20,125	8,932	24,215
Net Income (Loss) attributable to SEACOR Holdings Inc.	$ (215,897)	$ (68,782)	$ 100,132
Basic Earnings (Loss) Per Common Share of SEACOR Holdings Inc.	$ (12.76)	$ (3.94)	$ 5.18
Diluted Earnings (Loss) Per Common Share of SEACOR Holdings Inc.	$ (12.76)	$ (3.94)	$ 4.71
Weighted Average Common Shares Outstanding:
Basic Weighted Average Common Shares Outstanding	16,914,928	17,446,137	19,336,280
Diluted Weighted Average Common Shares Outstanding	16,914,928	17,446,137	25,765,325