Condensed Consolidated Statements Of Income - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Income Statement [Abstract]
Operating Revenues	$ 197,038,000	$ 281,609,000	$ 410,966,000	$ 542,253,000
Costs and Expenses [Abstract]
Operating	143,882,000	207,743,000	301,350,000	406,891,000
Administrative and general	34,175,000	38,674,000	69,879,000	77,561,000
Depreciation and amortization	31,361,000	32,079,000	62,350,000	63,509,000
Total costs and expenses	209,418,000	278,496,000	433,579,000	547,961,000
Gains (Losses) on Asset Dispositions and Impairments, Net	(17,771,000)	4,386,000	(17,554,000)	(460,000)
Operating Income (Loss)	(30,151,000)	7,499,000	(40,167,000)	(6,168,000)
Other Income (Expense):
Interest income	5,020,000	4,474,000	10,613,000	9,053,000
Interest expense	12,834,000	10,391,000	24,769,000	20,903,000
Debt extinguishment gains (losses), net	1,615,000	(29,536,000)	4,838,000	(29,536,000)
Marketable security gains (losses), net	(23,951,000)	10,249,000	(49,047,000)	1,128,000
Derivative gains (losses), net	(1,555,000)	1,426,000	1,065,000	(1,570,000)
Foreign currency gains (losses), net	(22,000)	2,436,000	15,000	443,000
Other, net	(7,652,000)	4,433,000	(7,384,000)	4,389,000
Total Other Nonoperating Income (Expense)	(39,379,000)	(16,909,000)	(64,669,000)	(36,996,000)
Loss Before Income Tax Expense (Benefit) and Equity in Earnings (Losses) of 50% or Less Owned Companies	(69,530,000)	(9,410,000)	(104,836,000)	(43,164,000)
Income Tax Expense (Benefit)	(25,759,000)	155,000	(40,590,000)	(11,799,000)
Loss Before Equity in Earnings (Losses) of 50% or Less Owned Companies	(43,771,000)	(9,565,000)	(64,246,000)	(31,365,000)
Equity in Earnings (Losses) of 50% or Less Owned Companies, Net of Tax	(7,162,000)	1,064,000	(7,211,000)	4,963,000
Net Loss	(50,933,000)	(8,501,000)	(71,457,000)	(26,402,000)
Net Income Attributable to Noncontrolling Interests in Subsidiaries	4,226,000	(9,188,000)	10,888,000	(7,520,000)
Net Income (Loss) attributable to SEACOR Holdings Inc.	$ (55,159,000)	$ 687,000	$ (82,345,000)	$ (18,882,000)
Basic Earnings (Loss) Per Common Share of SEACOR Holdings Inc.	$ (3.26)	$ 0.04	$ (4.88)	$ (1.06)
Diluted Earnings (Loss) Per Common Share of SEACOR Holdings Inc.	$ (3.26)	$ 0.04	$ (4.88)	$ (1.06)
Weighted Average Common Shares Outstanding:
Basic	16,928,722	17,780,759	16,873,045	17,779,250
Diluted	16,928,722	18,082,464	16,873,045	17,779,250