Seacor (CKH) 10-Q 4 Aug 17 2017 Q2 Quarterly report Financial data

Document And Entity Information

Document And Entity Information - shares	6 Months Ended
	Jun. 30, 2017	Aug. 01, 2017
Document And Entity Information [Abstract]
Entity Registrant Name	SEACOR HOLDINGS INC /NEW/
Entity Central Index Key	859,598
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Document Type	10-Q
Document Period End Date	Jun. 30, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	Q2
Amendment Flag	false
Entity Common Stock, Shares Outstanding		17,730,315
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Current Assets:
Cash and cash equivalents	$ 223,154	$ 256,638
Restricted cash	2,260	2,249
Marketable securities	75,071	76,137
Receivables:
Trade, net of allowance for doubtful accounts of $9,935 and $8,347 in 2017 and 2016, respectively	59,772	108,641
Other Receivables	35,704	35,482
Inventories	2,444	2,582
Prepaid expenses and other	4,814	3,707
Discontinued operations	23,105	277,365
Total current assets	426,324	762,801
Property and Equipment:
Property, Plant and Equipment, Gross	1,340,400	1,178,556
Accumulated depreciation	467,925	444,559
Property, Plant and Equipment, Other, Net in Service	872,475	733,997
Construction in progress	133,537	246,010
Net property and equipment	1,006,012	980,007
Investments, at Equity, and Advances to 50% or Less Owned Companies	174,106	175,461
Construction Reserve Funds	65,429	75,753
Goodwill	32,749	32,758
Intangible Assets, Net	18,931	20,078
Other Assets	17,739	17,189
Discontinued Operations	32,595	798,274
Total assets	1,773,885	2,862,321
Current Liabilities:
Current portion of long-term debt	125,655	163,202
Accounts payable and accrued expenses	32,437	59,563
Other current liabilities	49,602	62,164
Discontinued operations	6,324	85,020
Total current liabilities	214,018	369,949
Long-Term Debt	615,532	631,084
Exchange Option Liability on Subsidiary Convertible Senior Notes	0	19,436
Deferred Income Taxes	161,185	157,441
Deferred Gains and Other Liabilities	97,245	98,098
Discontinued Operations	7,681	390,045
Total liabilities	1,095,661	1,666,053
SEACOR Holdings Inc. stockholders’ equity:
Preferred stock, $.01 par value, 10,000,000 shares authorized; none issued nor outstanding	0	0
Common stock, $.01 par value, 60,000,000 shares authorized; 38,039,909 and 37,939,032 shares issued in 2017 and 2016, respectively	382	379
Additional paid-in capital	1,547,936	1,518,635
Retained earnings	360,139	910,723
Shares held in treasury of 20,634,001 and 20,538,327 in 2017 and 2016, respectively, at cost	1,364,273	1,357,331
Accumulated other comprehensive loss, net of tax	(545)	(11,514)
Stockholders' equity attributable to parent, total	543,639	1,060,892
Noncontrolling interests in subsidiaries	134,585	135,376
Total equity	678,224	1,196,268
Liabilities and stockholders' equity, total	$ 1,773,885	$ 2,862,321

Condensed Consolidated Balance3

Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Trade receivables, allowance for doubtful accounts	$ 2,306	$ 2,989
Common Stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	60,000,000	60,000,000
Common stock, shares issued	38,223,216	37,939,032
Treasury stock, shares held in treasury	20,636,178	20,538,327
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0

Condensed Consolidated Statemen

Condensed Consolidated Statements Of Income (Loss) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Income Statement [Abstract]
Operating Revenues	$ 115,791,000	$ 99,647,000	$ 234,205,000	$ 204,699,000
Costs and Expenses [Abstract]
Operating	69,686,000	64,027,000	144,898,000	127,063,000
Administrative and general	25,540,000	21,361,000	48,418,000	44,037,000
Depreciation and amortization	17,469,000	15,043,000	34,188,000	30,141,000
Total costs and expenses	112,695,000	100,431,000	227,504,000	201,241,000
Gains on Asset Dispositions and Impairments, Net	5,897,000	2,586,000	5,709,000	3,183,000
Operating Loss	8,993,000	1,802,000	12,410,000	6,641,000
Other Income (Expense):
Interest income	2,150,000	4,179,000	4,284,000	8,608,000
Interest expense	11,676,000	10,258,000	21,980,000	19,937,000
Debt extinguishment gains, net	(97,000)	1,615,000	(97,000)	4,838,000
Marketable security gains (losses), net	(21,674,000)	(21,459,000)	(838,000)	(42,970,000)
Derivative gains, net	16,897,000	(2,574,000)	19,727,000	(2,665,000)
Foreign currency gains, net	(1,470,000)	797,000	(71,000)	2,394,000
Other, net	424,000	(7,652,000)	4,000	(7,649,000)
Total Other Nonoperating Income (Expense)	(15,446,000)	(35,352,000)	1,029,000	(57,381,000)
Income (Loss) Before Income Tax Expense (Benefit) and Equity in Earnings (Losses) of 50% or Less Owned Companies	(6,453,000)	(33,550,000)	13,439,000	(50,740,000)
Income Tax Expense (Benefit)	(3,664,000)	(13,633,000)	232,000	(22,757,000)
Income (Loss) Before Equity in Earnings (Losses) of 50% or Less Owned Companies	(2,789,000)	(19,917,000)	13,207,000	(27,983,000)
Equity in Earnings (Losses) of 50% or Less Owned Companies, Net of Tax	2,333,000	(3,847,000)	2,441,000	(6,057,000)
Net Income (Loss)	(456,000)	(23,764,000)	15,648,000	(34,040,000)
Loss from Discontinued Operations, Net of Tax	(28,629,000)	(27,169,000)	(34,077,000)	(37,417,000)
Net Loss	(29,085,000)	(50,933,000)	(18,429,000)	(71,457,000)
Net Income Attributable to Noncontrolling Interests in Subsidiaries	3,723,000	4,226,000	10,296,000	10,888,000
Net Loss attributable to SEACOR Holdings Inc.	$ (32,808,000)	$ (55,159,000)	$ (28,725,000)	$ (82,345,000)
Basic Earnings (Loss) Per Common Share of SEACOR Holdings Inc.:
Continuing operations	$ (0.39)	$ (1.61)	$ 0.17	$ (2.63)
Discontinued operations	(1.52)	(1.65)	(1.85)	(2.25)
Basic Earnings (Loss) Per Common Share of SEACOR Holdings Inc.	(1.91)	(3.26)	(1.68)	(4.88)
Diluted Earnings (Loss) Per Common Share of SEACOR Holdings Inc.:
Continuing operations	(0.39)	(1.61)	0.17	(2.63)
Discontinued operations	(1.52)	(1.65)	(1.82)	(2.25)
Diluted Earnings (Loss) Per Common Share of SEACOR Holdings Inc.	$ (1.91)	$ (3.26)	$ (1.65)	$ (4.88)
Weighted Average Common Shares Outstanding:
Basic	17,207,831	16,928,722	17,141,306	16,873,045
Diluted	17,207,831	16,928,722	17,440,361	16,873,045

Condensed Consolidated Stateme5

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)

Condensed Consolidated Stateme6

Condensed Consolidated Statement Of Changes In Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Retained Earnings [Member]	Shares Held In Treasury [Member]	Accumulated Other Comprehensive Loss [Member]	Non-Controlling Interests In Subsidiaries [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Total equity	$ 1,196,268	$ 379	$ 1,518,635	$ 910,723	$ (1,357,331)	$ (11,514)	$ 135,376
Employee Stock Purchase Plan	728	0	0	0	728	0	0
Exercise of stock options	7,271	1	7,270	0	0	0	0
Director stock awards	43	0	43	0	0	0	0
Restricted stock	0	2	2	0	0	0	0
Exercise of conversion option in convertible debt	3	0	3	0	0	0	0
Distribution of SEACOR Marine stock to shareholders	(527,691)	0	2,656	(521,859)	0	10,125	(18,613)
Purchase of conversion option in convertible debt, net of tax	(793)	0	793	0	0	0	0
Purchases of treasury shares	(7,569)	0	0	0	(7,569)	0	0
Amortization of share awards	21,137	0	21,137	0	0	0	0
cancellation of restricted stock	0	0	101	0	101	0	0
Purchase of subsidiary shares from noncontrolling interests	(3,693)	0	(1,114)	0	0	0	(2,579)
Consolidation of 50% or less owned companies	17,374	0	0	0	0	0	17,374
Distributions to noncontrolling interests	7,430	0	0	0	0	0	7,430
Comprehensive income:
Net income attributable to SEACOR Holdings Inc.	(28,725)	0	0		0	0
Net Income Attributable to Noncontrolling Interests in Subsidiaries	10,296
Net Loss	(18,429)
Other comprehensive income	1,005	0	0	0	0	844	161
Total equity	$ 678,224	$ 382	$ 1,547,936	$ 360,139	$ (1,364,273)	$ (545)	$ 134,585

Condensed Consolidated Stateme7

Condensed Consolidated Statements Of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Statement of Cash Flows [Abstract]
Net Cash Provided by Operating Activities	$ 77,351	$ 46,268
Cash Flows from Investing Activities
Purchases of property and equipment	80,987	155,990
Proceeds from disposition of property and equipment	19,817	142,020
Investments in and advances to 50% or less owned companies	7,284	4,264
Return of investments and advances from 50% or less owned companies	3,940	7,559
Net repayments on revolving credit line to 50% or less owned companies	0	(1,099)
(Issuances of) payments received on third party leases and notes receivable, net	(580)	1,584
Net increase in restricted cash	11	1,742
Decrease in construction reserve funds	20,124	11,810
Increase in construction reserve funds	9,800	0
Net cash used in investing activities	(54,781)	(122)
Cash Flows from Financing Activities
Payments on long-term debt and capital lease obligations	88,049	91,201
Proceeds from issuance of long term debt, net of issue costs	27,900	54,379
Purchase of conversion option in convertible debt	1,220	4,990
Common stock acquired for treasury	7,569	2,396
Proceeds and tax benefits from share award plans	7,999	1,249
Distributions to noncontrolling interests	0	(196)
Net cash used in financing activities	(60,939)	(43,155)
Effect of Exchange Rate Changes on Cash and Cash Equivalents	913	(1,571)
Net Increase (Decrease) in Cash and Cash Equivalents from Continuing Operations	(37,456)	1,420
Cash Flows from Discontinued Operations:
Operating Activities	26,686	(11,752)
Investing Activities	(15,773)	26,075
Financing Activities	(7,149)	(5,680)
Effects of Exchange Rate Changes on Cash and Cash Equivalents	208	483
Net Increase in Cash and Cash Equivalents from Discontinued Operations	3,972	9,126
Net Increase (Decrease) in Cash and Cash Equivalents	(33,484)	10,546
Cash and Cash Equivalents, Beginning of Period	256,638	357,146
Cash and Cash Equivalents, End of Period	$ 223,154	$ 367,692

Basis of Presentation and Accou

Basis of Presentation and Accounting Policy	6 Months Ended
	Jun. 30, 2017
Accounting Policies [Abstract]
Basis of Presentation and Accounting Policy	BASIS OF PRESENTATION AND ACCOUNTING POLICIES The condensed consolidated financial information for the three and six months ended June 30, 2017 and 2016 has been prepared by the Company and has not been audited by its independent registered certified public accounting firm. The condensed consolidated financial statements include the accounts of SEACOR Holdings Inc. and its consolidated subsidiaries. In the opinion of management, all adjustments (consisting of normal recurring adjustments) have been made to fairly present the Company’s financial position as of June 30, 2017 , its results of operations for the three and six months ended June 30, 2017 and 2016 , its comprehensive loss for the three and six months ended June 30, 2017 and 2016 , its changes in equity for the six months ended June 30, 2017 , and its cash flows for the six months ended June 30, 2017 and 2016 . Results of operations for the interim periods presented are not necessarily indicative of operating results for the full year or any future periods. Certain information and footnote disclosures normally included in financial statements prepared in accordance with generally accepted accounting principles in the United States have been condensed or omitted. These condensed consolidated financial statements should be read in conjunction with the financial statements and related notes thereto included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2016 . Unless the context otherwise indicates, any reference in this Quarterly Report on Form 10-Q to the “Company” refers to SEACOR Holdings Inc. and its consolidated subsidiaries and any reference in this Quarterly Report on Form 10-Q to “SEACOR” refers to SEACOR Holdings Inc without its consolidated subsidiaries. Capitalized terms used and not specifically defined herein have the same meaning given those terms in the Company's Annual report on Form 10-K for the year ended December 31, 2016 . Discontinued Operations. On June 1, 2017, the Company completed the spin-off of SEACOR Marine Holdings Inc. (“SEACOR Marine”), the company that operated SEACOR’s Offshore Marine Services business segment (the “Spin-off”), by means of a dividend of all the issued and outstanding common stock of SEACOR Marine to SEACOR’s shareholders. SEACOR Marine is now an independent company whose common stock is listed on the New York Stock Exchange under the symbol “SMHI.” For all periods presented herein, the Company has reported the historical financial position, results of operations and cash flows of SEACOR Marine as discontinued operations (see Note 13). On July 3, 2017, the Company effected the sale of its 70% interest in Illinois Corn Processing LLC (“ICP”), the company that operated SEACOR’s Illinois Corn Processing business segment, through a merger transaction whereby the Company received $21.0 million in cash and issued a note to the buyer for $32.7 million , subject to a working capital adjustment, resulting in a third quarter gain of $11.6 million , net of tax. The principal amount of the promissory note accrues interest at a rate per annum equal to the three-month London Interbank Offered Rate (“LIBOR”) plus an applicable margin of 5% for the first three months, 8% for the next three months and 10% thereafter, and matures on January 3, 2019. The obligations of ICP under the promissory note are secured by the equity and substantially all of the assets of ICP. ICP operates a single-site alcohol manufacturing, storage and distribution facility producing alcohol used in the food, beverage, industrial and petrochemical end-markets. For all periods presented herein, the Company has reported the historical financial position, results of operations and cash flows of ICP as discontinued operations (see Note 13). Subsequent Event. On July 3, 2017, International Shipholding Corporation (“ISH”) emerged from bankruptcy pursuant to its chapter 11 plan of reorganization (the “Plan”) that had been confirmed by the U.S. Bankruptcy Court for the Southern District of New York. Pursuant to the Plan, SEACOR Ocean Transport Inc., a wholly-owned subsidiary of the Company, acquired all of the equity of the reorganized ISH. ISH, through its subsidiaries, operates a diversified fleet of U.S. and foreign-flag vessels that provide worldwide and domestic maritime transportation services to commercial and governmental customers primarily under medium to long-term charters and contracts. Under the terms of the Plan, the Company paid $10.5 million in cash, converted $18.1 million of debtor in possession financing into equity and borrowed $25.0 million under a new credit facility that is secured by the assets and equity of ISH and is non-recourse to SEACOR and its subsidiaries other than ISH (see Note 4). Revenue Recognition. The Company recognizes revenue when it is realized or realizable and earned. Revenue is realized or realizable and earned when persuasive evidence of an arrangement exists, delivery has occurred or services have been rendered, the price to the buyer is fixed or determinable, and collectability is reasonably assured. Revenue that does not meet these criteria is deferred until the criteria are met. Property and Equipment. Equipment, stated at cost, is depreciated using the straight-line method over the estimated useful life of the asset to an estimated salvage value. With respect to each class of asset, the estimated useful life is based upon a newly built asset being placed into service and represents the time period beyond which it is typically not justifiable for the Company to continue to operate the asset in the same or similar manner. From time to time, the Company may acquire older assets that have already exceeded the Company’s useful life policy, in which case the Company depreciates such assets based on its best estimate of remaining useful life, typically the next survey or certification date. As of June 30, 2017 , the estimated useful life (in years) of each of the Company’s major categories of new equipment was as follows: Inland river dry-cargo and deck barges 20 Inland river liquid tank barges 25 Inland river towboats and harbor boats 25 Product tankers - U.S.-flag 25 Short-sea Container/RORO (1) vessels 20 Harbor and offshore tugs 25 Ocean liquid tank barges 25 Terminal facilities 20 ______________________ (1) Roll on/Roll off (“RORO”). Equipment maintenance and repair costs including the costs of routine overhauls, drydockings and inspections performed on vessels and equipment are charged to operating expense as incurred. Expenditures that extend the useful life or improve the marketing and commercial characteristics of equipment as well as major renewals and improvements to other properties are capitalized. Certain interest costs incurred during the construction of equipment are capitalized as part of the assets’ carrying values and are amortized over such assets’ estimated useful lives. During the six months ended June 30, 2017 , capitalized interest totaled $2.1 million . Impairment of Long-Lived Assets. The Company performs an impairment analysis of long-lived assets used in operations, including intangible assets, when indicators of impairment are present. These indicators may include a significant decrease in the market price of a long-lived asset or asset group, a significant adverse change in the extent or manner in which a long-lived asset or asset group is being used or in its physical condition, or a current period operating or cash flow loss combined with a history of operating or cash flow losses or a forecast that demonstrates continuing losses associated with the use of a long-lived asset or asset group. If the carrying values of the assets are not recoverable, as determined by the estimated undiscounted cash flows, the estimated fair value of the assets or asset groups are compared to their current carrying value and impairment charges are recorded if the carrying value exceeds fair value. The Company performs its testing on an asset or asset group basis. The Company’s estimates of undiscounted cash flows are highly subjective and actual results may vary from the Company’s estimates due to the uncertainty regarding projected financial performance. Generally, fair value is determined using valuation techniques, such as expected discounted cash flows or appraisals, as appropriate. During the six months ended June 30, 2017 , the Company recognized impairment charges of $0.4 million related to long-lived assets held for use. During the six months ended June 30, 2016 , the Company recognized no impairment charges related to long-lived assets held for use. Impairment of 50% or Less Owned Companies. Investments in 50% or less owned companies are reviewed periodically to assess whether there is an other-than-temporary decline in the carrying value of the investment. In its evaluation, the Company considers, among other items, recent and expected financial performance and returns, impairments recorded by the investee and the capital structure of the investee. When the Company determines the estimated fair value of an investment is below carrying value and the decline is other-than-temporary, the investment is written down to its estimated fair value. Actual results may vary from the Company’s estimates due to the uncertainty regarding projected financial performance, the severity and expected duration of declines in value, and the available liquidity in the capital markets to support the continuing operations of the investee, among other factors. Although the Company believes its assumptions and estimates are reasonable, the investee’s actual performance compared with the estimates could produce different results and lead to additional impairment charges in future periods. During the six months ended June 30, 2017 and 2016 , the Company did not recognize any impairment charges related to its 50% or less owned companies. Income Taxes. During the six months ended June 30, 2017 , the Company’s effective income tax rate of 1.7% was primarily due to taxes not provided on income attributable to noncontrolling interests (see Note 8). Deferred Gains. The Company has sold certain equipment to its 50% or less owned companies, entered into vessel sale-leaseback transactions with finance companies, and provided seller financing on sales of its equipment to third parties and its 50% or less owned companies. A portion of the gains realized from these transactions were deferred and recorded in deferred gains and other liabilities in the accompanying condensed consolidated balance sheets. Deferred gain activity related to these transactions for the six months ended June 30 was as follows (in thousands): 2017 2016 Balance at beginning of period $ 82,423 $ 92,610 Adjustments to deferred gains arising from asset sales 7,720 9,003 Amortization of deferred gains included in operating expenses as a reduction to rental expense (7,242 ) (7,367 ) Amortization of deferred gains included in gains on asset dispositions and impairments, net (1,210 ) (1,210 ) Other — (1,697 ) Balance at end of period $ 81,691 $ 91,339 Accumulated Other Comprehensive Loss. The components of accumulated other comprehensive loss were as follows (in thousands): SEACOR Holdings Inc. Stockholders’ Equity Noncontrolling Interests Foreign Currency Translation Adjustments Derivative Losses on Cash Flow Hedges, net Other Total Foreign Currency Translation Adjustments Derivative Losses on Cash Flow Hedges, net Other Other Comprehensive Income December 31, 2016 $ (11,593 ) $ 75 $ 4 $ (11,514 ) $ (1,613 ) $ (17 ) $ 3 Distribution of SEACOR Marine stock to shareholders 10,031 94 — 10,125 — — — Other comprehensive income (loss) 1,569 (260 ) (11 ) 1,298 153 13 (5 ) $ 1,459 Income tax (expense) benefit (549 ) 91 4 (454 ) — — — (454 ) Six Months Ended June 30, 2017 $ (542 ) $ — $ (3 ) $ (545 ) $ (1,460 ) $ (4 ) $ (2 ) $ 1,005 Loss Per Share. Basic loss per common share of SEACOR is computed based on the weighted average number of common shares issued and outstanding during the relevant periods. Diluted loss per common share of SEACOR is computed based on the weighted average number of common shares issued and outstanding plus the effect of potentially dilutive securities through the application of the treasury stock and if-converted methods. Dilutive securities for this purpose assumes restricted stock grants have vested, common shares have been issued pursuant to the exercise of outstanding stock options and common shares have been issued pursuant to the conversion of all outstanding convertible notes. Computations of basic and diluted loss per common share of SEACOR were as follows (in thousands, except share data): Three Months Ended June 30, Six Months Ended June 30, Net Loss attributable to SEACOR Average O/S Shares Per Share Net Loss Attributable to SEACOR Average O/S Shares Per Share 2017 Basic Weighted Average Common Shares Outstanding $ (32,808 ) 17,207,831 $ (1.91 ) $ (28,725 ) 17,141,306 $ (1.68 ) Effect of Dilutive Share Awards: Options and Restricted Stock (1) — — — 299,055 Convertible Notes (2) — — — — Diluted Weighted Average Common Shares Outstanding $ (32,808 ) 17,207,831 $ (1.91 ) $ (28,725 ) 17,440,361 $ (1.65 ) 2016 Basic Weighted Average Common Shares Outstanding $ (55,159 ) 16,928,722 $ (3.26 ) $ (82,345 ) 16,873,045 $ (4.88 ) Effect of Dilutive Share Awards: Options and Restricted Stock (3) — — — — Convertible Notes (4) — — — — Diluted Weighted Average Common Shares Outstanding $ (55,159 ) 16,928,722 $ (3.26 ) $ (82,345 ) 16,873,045 $ (4.88 ) ______________________ (1) For the three and six months ended June 30, 2017 , diluted loss per common share of SEACOR excluded 2,644,489 and 1,563,901 , respectively, of certain share awards as the effect of their inclusion in the computation would be anti-dilutive. Diluted weighted average shares outstanding are calculated based on continuing operations. (2) For the three and six months ended June 30, 2017 , diluted loss per common share of SEACOR excluded 2,693,475 and 2,793,144 , respectively, of common shares issuable pursuant to the Company’s 2.5% Convertible Senior Notes and 2,801,147 and 2,801,147 , respectively, of common shares issuable pursuant to the Company’s 3.0% Convertible Senior Notes as the effect of their inclusion in the computation would be anti-dilutive. (3) For the three and six months ended June 30, 2016 , diluted loss per common share of SEACOR excluded 2,024,421 and 2,024,421 , respectively, of certain share awards as the effect of their inclusion in the computation would be anti-dilutive. (4) For the three and six months ended June 30, 2016 , diluted loss per common share of SEACOR excluded 2,975,847 and 3,177,620 , respectively, of common shares issuable pursuant to the Company’s 2.5% Convertible Senior Notes, 1,825,326 and 1,825,326 , respectively, of common shares issuable pursuant to the Company’s 3.0% Convertible Senior Notes and 2,243,500 and 2,243,500 , respectively, of common shares issuable pursuant to the Company’s 3.75% Subsidiary Convertible Senior Notes as the effect of their inclusion in the computation would be anti-dilutive. New Accounting Pronouncements. On May 28, 2014, the Financial Accounting Standards Board (“FASB”) issued a comprehensive new revenue recognition standard that will supersede nearly all existing revenue recognition guidance under generally accepted accounting principles in the United States. The core principal of the new standard is that a company will recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which the company expects to be entitled in exchange for those goods or services. The new standard is effective for annual and interim periods beginning after December 15, 2017 and early adoption is permitted. The Company will adopt the new standard on January 1, 2018 and expects to use the modified retrospective approach upon adoption. The Company is currently determining the impact, if any, the adoption of the new accounting standard will have on its consolidated financial position, results of operations or cash flows. Principal versus agent considerations of the new standard with respect to the Company’s vessel management services and pooling arrangements may result in a gross presentation of operating revenues and expenses compared with its current net presentation for results from managed and pooled third party equipment. On February 25, 2016, the FASB issued a comprehensive new leasing standard, which improves transparency and comparability among companies by requiring lessees to recognize a lease liability and a corresponding lease asset for virtually all lease contracts. It also requires additional disclosures about leasing arrangements. The new standard is effective for interim and annual periods beginning after December 15, 2018 and requires a modified retrospective approach to adoption. Early adoption is permitted. The Company has not yet determined what impact, if any, the adoption of the new standard will have on its consolidated financial position, results of operations or cash flows. On August 26, 2016, the FASB issued an amendment to the accounting standard which amends or clarifies guidance on classification of certain transactions in the statement of cash flows, including classification of proceeds from the settlement of insurance claims, debt prepayments, debt extinguishment costs and contingent consideration payments after a business combination. This new standard is effective for the Company as of January 1, 2018 and early adoption is permitted. The Company has not yet determined what impact, if any, the adoption of the new standard will have on its consolidated financial position, results of operations or cash flows. On October 24, 2016, the FASB issued a new accounting standard, which requires companies to account for the income tax effects of intercompany sales and transfers of assets other than inventory. The new standard is effective for interim and annual periods beginning after December 31, 2017 and requires a modified retrospective approach to adoption. The Company does not expect the adoption of the new standard will have a material impact on its consolidated financial position, results of operations or cash flows. On November 17, 2016, the FASB issued an amendment to the accounting standard which requires that restricted cash and restricted cash equivalents be included with cash and cash equivalents when reconciling the beginning-of-period and end-of-period total cash amounts shown on the statement of cash flows. The new standard is effective for fiscal years beginning after December 15, 2018, and interim periods within fiscal years beginning after December 15, 2019. Early adoption is permitted. The Company has not yet determined what impact, if any, the adoption of the new standard will have on its consolidated financial position, results of operations or cash flows. On January 26, 2017, the FASB issued an amendment to the accounting standard which simplified wording and removes step two of the goodwill impairment test. A goodwill impairment will now be the amount by which a reporting units carrying value exceeds its fair value, not to exceed the carrying amount of goodwill. The FASB also eliminated the requirements for any reporting unit with a zero or negative carrying amount to perform a qualitative assessment and, if it fails that qualitative test, to perform step two of the goodwill test. The new standard is effective for annual or interim goodwill impairment tests in fiscal years beginning after December 15, 2020, with early adoption permitted for interim or annual goodwill impairment tests on testing dates after January 1, 2017. The Company has not yet determined what impact, if any, the adoption of the new standard will have on its consolidated financial position, results of operations or cash flows.

Equipment Acquisitions, Disposi

Equipment Acquisitions, Dispositions and Depreciation and Impairment Policies Equipment Acquisitions, Dispositions and Depreciation and Impairment Policies (Notes)	6 Months Ended
	Jun. 30, 2017
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment Disclosure [Text Block]	EQUIPMENT ACQUISITIONS AND DISPOSITIONS During the six months ended June 30, 2017 , capital expenditures were $81.0 million and primarily relates to equipment ordered prior to 2017. Equipment deliveries during the six months ended June 30, 2017 included one liquid tank barge, one inland river towboat, one U.S.-flag product tanker, one U.S.-flag harbor tug and two foreign-flag harbor tugs. During the six months ended June 30, 2017 , the Company sold 50 dry-cargo barges, one inland river towboat and other property and equipment for net proceeds of $19.8 million and gains of $13.0 million , of which $5.3 million were recognized currently and $7.7 million were deferred (see Note 1). Equipment dispositions included the sale-leaseback of 50 dry cargo barges for $12.5 million with leaseback terms of 84 months. In addition, the Company recognized previously deferred gains of $1.2 million . The Company also recognized a loss of $0.4 million related to the total loss of one inland river specialty barge.

Investments, At Equity, And Adv

Investments, At Equity, And Advances To 50% Or Less Owned Companies	6 Months Ended
	Jun. 30, 2017
Equity Method Investment, Summarized Financial Information [Abstract]
Investments, At Equity, And Advances To 50% Or Less Owned Companies	INVESTMENTS, AT EQUITY, AND ADVANCES TO 50% OR LESS OWNED COMPANIES SCFCo. SCFCo was established to operate inland river towboats and inland river dry-cargo barges on the Parana-Paraguay Rivers in South America and a terminal facility at Port Ibicuy, Argentina. During the six months ended June 30, 2017 , the Company and its partner each made working capital advances of $0.5 million in cash to SCFCo, received working capital repayments of $0.5 million and converted $3.0 million of loans to capital. As of June 30, 2017 , the Company had outstanding loans and working capital advances to SCFCo of $29.0 million . Trailer Bridge. Trailer Bridge is an operator of U.S.-flag deck and RORO barges and provides marine transportation services between Jacksonville, Florida, San Juan, Puerto Rico and Puerto Plata, Dominican Republic. The Company provides secured financing to Trailer Bridge and, during the six months ended June 30, 2017 , the Company provided advances of $2.0 million on the secured financing. As of June 30, 2017 , the outstanding amount on the secured financing was $6.0 million , inclusive of accrued and unpaid interest. SeaJon. SeaJon owned an articulated tug-barge operating in the Great Lakes trade that was sold to a third party in June 2017. During the six months ended June 30, 2017 , the Company received dividends of $12.5 million and capital distributions of $3.4 million from SeaJon. Kotug. On April 1, 2017, the Company and Kotug Caribbean Holdings LLC formed Kotug Seabulk Maritime LLC (“Kotug”) to operate four foreign-flag harbor tugs and one foreign-flag ocean liquid tank barge in Freeport, Grand Bahama. The Company has a 50% ownership interest in Kotug. During the six months ended June 30, 2017 , the Company and its partner each contributed capital of $0.3 million in cash. VA&E. VA&E primarily focuses on the global origination, trading and merchandising of sugar, pairing producers and buyers and arranging for the transportation and logistics of the product. The Company provides an uncommitted credit facility of up to $3.5 million and a subordinated loan of $3.5 million to VA&E. During the six months ended June 30, 2017 , VA&E borrowed $3.5 million on the credit facility. As of June 30, 2017 , the outstanding balance on the credit facility and subordinated loan was $7.3 million including accrued and unpaid interest. Avion. Avion is a distributor of aircraft and aircraft related parts. During the six months ended June 30, 2017 , the Company made advances of $1.0 million to Avion. As of June 30, 2017 , the Company had outstanding advances to Avion of $4.0 million .

Long-Term Debt

Long-Term Debt	6 Months Ended
	Jun. 30, 2017
Long-term Debt and Capital Lease Obligations [Abstract]
Long-Term Debt	LONG-TERM DEBT SEACOR’s Board of Directors previously approved a securities repurchase plan that authorizes the Company to acquire SEACOR common stock, par value $0.01 per share (“Common Stock”), 7.375% Senior Notes, 3.0% Convertible Senior Notes, and 2.5% Convertible Senior Notes (collectively the “Securities”) through open market purchases, privately negotiated transactions or otherwise, depending on market conditions. As of June 30, 2017 , the Company’s remaining repurchase authority for the Securities was $90.7 million . 3.0% Convertible Senior Notes. In connection with the Spin-off, the conversion rate of the 3.0% Convertible Senior Notes was adjusted to 12.1789 . The Company has reserved the maximum number of shares of Common Stock needed for conversion, or 2,801,147 shares as of June 30, 2017 . 2.5% Convertible Senior Notes. During the six months ended June 30, 2017 , the Company repurchased $48.4 million in principal amount of its 2.5% Convertible Senior Notes for total consideration of $48.6 million . Consideration of $47.4 million was allocated to the settlement of the long-term debt resulting in debt extinguishment gains of $0.1 million included in the accompanying condensed consolidated statements of loss. Consideration of $1.2 million was allocated to the purchase of the conversion option embedded in the 2.5% Convertible Senior Notes as included in the accompanying consolidated statements of changes in equity. As of June 30, 2017 , the remaining principal amount outstanding of $108.7 million is included in current liabilities as the holders may require the Company to repurchase these notes on December 19, 2017. Subsequent to June 30, 2017 , the Company repurchased an additional $6.5 million in principal amount of its 2.5% Convertible Senior Notes for total consideration of $6.5 million . In connection with the Spin-off, the conversion rate of the 2.5% Convertible Senior Notes was adjusted to 18.4176 . The Company has reserved the maximum number of shares of Common Stock needed for conversion, or 2,001,993 shares as of June 30, 2017 . 7.375% Senior Notes. During the six months ended June 30, 2017 , the Company repurchased $7.6 million in principal amount of its 7.375% Senior Notes for $7.7 million resulting in debt extinguishment losses of $0.2 million included in the accompanying condensed consolidated statements of loss. The outstanding principal amount of these notes outstanding was $153.1 million as of June 30, 2017 . SEA-Vista Credit Facility. During the six months ended June 30, 2017 , SEA-Vista borrowed $27.9 million and repaid $30.9 million on the Revolving Loan and made scheduled repayments of $1.8 million on the Term A-1 Loan. As of June 30, 2017 , SEA-Vista had $17.0 million of remaining borrowing capacity under the Revolving Loan. Subsequent to June 30, 2017 , SEA-Vista borrowed $11.0 million on the Revolving Loan. ICP Revolving Credit Facility. During June 2017, ICP terminated its credit facility, which had no outstanding balance. For all periods presented herein, the Company has reported the historical financial position, results of operations and cash flows of ICP as discontinued operations (see Notes 1 and 13). ISH Credit Facility. On July 3, 2017, ISH emerged from bankruptcy pursuant to the Plan. In conjunction with the emergence ISH entered into a $25.0 million credit facility that matures in July 2020. The facility consists of two tranches: (i) a $5.0 million revolving credit facility (the “ISH Revolving Loan”) and (ii) a $20.0 million term loan (the “ISH Term Loan”). The proceeds from the facility will be used for general working capital purposes and contributions to ISH’s creditors in accordance with the Plan. During July 2017, ISH drew $20.0 million under ISH Term Loan and $5.0 million under ISH Revolving Loan and repaid $6.5 million on ISH Term Loan and $3.5 million on ISH Revolving Loan. Both loans bear interest at a variable rate either determined by reference to the LIBOR rate multiplied by the Statutory Reserve Rate or Prime Rate plus an applicable rate. A quarterly fee is payable on the unused commitment of the ISH Revolving Loan. Beginning September 30, 2017, ISH is required to make quarterly prepayments on the ISH Term Loan of $0.7 million . Commencing with the calendar year ending December 31, 2018, ISH is required to make annual prepayments on the ISH Term Loan in an amount equal to 50% of excess cash flow as defined. The ISH Credit Facility contains various financial maintenance and restrictive covenants including indebtedness to EBITDA and adjusted EBITDA to interest expense maintenance covenants, as defined. The ISH Credit Facility is non-recourse to SEACOR and its subsidiaries other than ISH. Other. During the six months ended June 30, 2017 , the Company made scheduled payments on other long-term debt of $0.2 million . Letters of Credit. As of June 30, 2017 , the Company had outstanding letters of credit totaling $26.2 million with various expiration dates through 2019 , including $16.7 million that have been issued on behalf of SEACOR Marine. Guarantees. The Company has guaranteed the payments of amounts owed under certain sale-leaseback transactions, equipment financing and multi-employer pension obligations on behalf of SEACOR Marine. As of June 30, 2017 , these guarantees on behalf of SEACOR Marine totaled $90.9 million and decline as payments are made on the outstanding obligations. The Company earns a fee of 50 basis points per annum on these guarantees and outstanding letters of credit. For the three and six months ended June 30, 2017 , the Company earned fees of $0.2 million and $0.4 million , respectively. For the three and six months ended June 30, 2016 , the Company earned fees of $0.2 million and $0.4 million , respectively.

Derivative Instruments And Hedg

Derivative Instruments And Hedging Strategies	6 Months Ended
	Jun. 30, 2017
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Instruments And Hedging Strategies	DERIVATIVE INSTRUMENTS AND HEDGING STRATEGIES Cash Flow Hedges. SeaJon, one of the Company’s 50% or less owned companies, had an interest rate swap agreement designated as a cash flow hedge that matured in April 2017. This interest rate swap called for SeaJon to pay a fixed interest rate of 2.79% on the amortized notional value and receive a variable interest rate based on LIBOR on the amortized notional value. By entering into this interest rate swap agreement, SeaJon converted the variable LIBOR component of certain of its outstanding borrowings to a fixed interest rate. Other Derivative Instruments. The Company recognized gains (losses) on derivative instruments not designated as hedging instruments for the six months ended June 30 as follows (in thousands): 2017 2016 Exchange option liability on subsidiary convertible senior notes $ 19,436 $ (2,560 ) Forward currency exchange, option and future contracts 291 (107 ) Exchange traded commodity swap, option and future contracts — 2 $ 19,727 $ (2,665 ) The exchange option liability on subsidiary convertible senior notes terminated as a consequence of the Spin-off. The Company enters and settles forward currency exchange, option and future contracts with respect to various foreign currencies. These contracts enable the Company to buy currencies in the future at fixed exchange rates, which could offset possible consequences of changes in currency exchange rates with respect to the Company’s business conducted outside of the United States. As of June 30, 2017 , there were no outstanding forward currency exchange contracts.
Recognized Gains (Losses) On Derivative Instruments Not Designated As Hedging Instruments	The Company recognized gains (losses) on derivative instruments not designated as hedging instruments for the six months ended June 30 as follows (in thousands): 2017 2016 Exchange option liability on subsidiary convertible senior notes $ 19,436 $ (2,560 ) Forward currency exchange, option and future contracts 291 (107 ) Exchange traded commodity swap, option and future contracts — 2 $ 19,727 $ (2,665 )

Stock Repurchases

Stock Repurchases	6 Months Ended
	Jun. 30, 2017
Common Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Stock Repurchases	STOCK REPURCHASES SEACOR’s Board of Directors previously approved a securities repurchase plan that authorizes the Company to acquire its Securities through open market purchases, privately negotiated transactions or otherwise, depending on market conditions. As of June 30, 2017 , the Company’s repurchase authority for the Securities was $90.7 million . During the six months ended June 30, 2017 , the Company purchased 110,298 shares of Common Stock for treasury for an aggregate purchase price of $7.6 million from its employees to cover their tax withholding obligations related to share award transactions. These shares were purchased in accordance with the terms of the Company’s Share Incentive Plans and not pursuant to the repurchase authorization granted by SEACOR’s Board of Directors.

Noncontrolling Interests in Sub

Noncontrolling Interests in Subsidiaries (Notes)	6 Months Ended
	Jun. 30, 2017
Noncontrolling Interest [Abstract]
Noncontrolling Interests in Subsidiaries Disclosure [Text Block]	NONCONTROLLING INTERESTS IN SUBSIDIARIES Noncontrolling interests in the Company’s consolidated subsidiaries were as follows (in thousands): Noncontrolling Interests June 30, 2017 December 31, 2016 Inland River Services: Other 3.0 % – 51.8% $ 963 $ 980 Shipping Services: SEA-Vista 49% 118,798 106,054 Discontinued Operations 1.8 % – 50.0% 14,673 28,190 Other 5.0 % – 14.6% 151 152 $ 134,585 $ 135,376 SEA-Vista. SEA-Vista owns and operates the Company’s fleet of U.S.-flag product tankers used in the U.S. coastwise trade of crude oil, petroleum and specialty chemical products. As of June 30, 2017 , the net assets of SEA-Vista were $242.4 million . During the six months ended June 30, 2017 , the net income of SEA-Vista was $26.0 million , of which $12.7 million was attributable to noncontrolling interests. During the six months ended June 30, 2016 , the net income of SEA-Vista was $21.7 million , of which $10.6 million was attributable to noncontrolling interests. Discontinued Operations. As of December 31, 2016, discontinued operations primarily consisted of noncontrolling interests in Windcat Workboats, a subsidiary of SEACOR Marine, and noncontrolling interests in ICP. As of June 30, 2017 , discontinued operations consisted of noncontrolling interests in ICP (see Notes 1 and 13).

Multiemployer Pension Plans

Multiemployer Pension Plans	6 Months Ended
	Jun. 30, 2017
Compensation and Retirement Disclosure [Abstract]
Multiemployer Pension Plans	MULTI-EMPLOYER PENSION PLANS AMOPP. During the six months ended June 30, 2017 , the Company received notification from the AMOPP that the Company’s withdrawal liability as of September 30, 2016 would have been $28.6 million based on an actuarial valuation performed as of that date. That liability may change in future years based on various factors, primarily employee census. As of June 30, 2017 , the Company has no intention to withdraw from the AMOPP and no deficit amounts have been invoiced. Depending upon the results of the future actuarial valuations and the ten-year rehabilitation plan, it is possible that the AMOPP will experience further funding deficits, requiring the Company to recognize additional payroll related operating expenses in the periods invoices are received or contribution levels are increased.

Share Based Compensation

Share Based Compensation	6 Months Ended
	Jun. 30, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Share Based Compensation	SHARE BASED COMPENSATION Transactions in connection with the Company’s share based compensation plans during the six months ended June 30, 2017 were as follows: Director stock awards granted 750 Employee Stock Purchase Plan (“ESPP”) shares issued 14,624 Restricted stock awards granted 144,750 Restricted stock awards canceled 2,117 Stock Option Activities: Outstanding as of December 31, 2016 1,639,865 Granted (1) 916,258 Exercised (138,648 ) Forfeited (3,374 ) Expired (21,442 ) Outstanding as of June 30, 2017 2,392,659 Shares available for future grants and ESPP purchases as of June 30, 2017 (2) 504,570 ______________________ (1) On June 2, 2017, the Company granted 846,353 stock options to existing option holders under make-whole provisions upon the Spin-off of SEACOR Marine. (2) Shares available for future grants and ESPP purchases were adjusted on June 2, 2017 to reflect the Spin-off of SEACOR Marine in accordance with make-whole provisions of the plans.

Commitments And Contingencies

Commitments And Contingencies	6 Months Ended
	Jun. 30, 2017
Commitments and Contingencies Disclosure [Abstract]
Commitments And Contingencies	COMMITMENTS AND CONTINGENCIES The Company's capital commitments as of June 30, 2017 by year of expected payment were as follows (in thousands): Remainder of 2017 2018 2019 Total Shipping Services $ 8,356 $ 2,259 $ — $ 10,615 Inland River Services 11,780 926 463 13,169 $ 20,136 $ 3,185 $ 463 $ 23,784 Shipping Services’ capital commitments included one U.S.-flag chemical and petroleum articulated tug-barge and two U.S.-flag harbor tugs. Inland River Services’ capital commitments included two inland river towboats and other equipment and improvements. On December 15, 2010, ORM and NRC were named as defendants in one of the several “master complaints” filed in the overall multi-district litigation relating to the Deepwater Horizon oil spill response and clean-up in the Gulf of Mexico, which is currently pending in the U.S. District Court for the Eastern District of Louisiana (the “MDL”). The “B3” master complaint naming ORM and NRC asserts various claims on behalf of a putative class against multiple defendants concerning the clean-up activities generally and the use of dispersants specifically. Both prior to and following the filing of the aforementioned master complaint, individual civil actions naming the Company, ORM, and/or NRC alleging B3 exposure-based injuries and/or damages were consolidated with the MDL and stayed pursuant to court order, discussed in turn below. The Company has continually taken the position that all of the B3 claims asserted against ORM and NRC have no merit. On February 16, 2016, all but eleven B3 claims against ORM and NRC were dismissed with prejudice, whether by joinder in the master complaint, individual complaint, or otherwise (the “B3 Dismissal Order”). On August 2, 2016, the Court granted an omnibus motion for summary judgment as it concerns ORM and NRC in its entirety, dismissing the remaining eleven plaintiffs’ against ORM and NRC with prejudice (the “Remaining Eleven Plaintiffs’ Dismissal Order”). As noted above, various civil actions concerning the Deepwater Horizon clean-up have been consolidated with the MDL, although a number of them have been dismissed or otherwise resolved. A summary of the remaining claims is as follows: • On October 3, 2012, ORM and NRC were served with a Rule 14(c) Third-Party Complaint by Jambon Supplier II, L.L.C. and Jambon Marine Holdings L.L.C. in their Limitation of Liability action, in the Matter of Jambon Supplier II, L.L.C., et al. , No. 2:12-CV-00426 (E.D. La.) (the “ Jambon Action”). This Third-Party Complaint alleges that if claimant David Dinwiddie, who served as a clean-up crewmember aboard the M/V JAMBON SUPPLIER II vessel during the clean-up efforts, was injured as a result of his exposure to dispersants and chemicals during the course and scope of his employment, then said injuries were caused by the third-party defendants. The Jambon Action remains stayed. • On April 8, 2013, the Company, ORM, and NRC were named as defendants in William and Dianna Fitzgerald v. BP Exploration et al. , No. 2:13-CV-00650 (E.D. La.) (the “ Fitzgerald Action”), which is a suit by a husband and wife whose son allegedly participated in the clean-up effort and became ill as a result of his exposure to oil and dispersants. While the decedent in the Fitzgerald Action’s claims against ORM and NRC were dismissed by virtue of the Remaining Eleven Plaintiffs’ Dismissal Order, the claim as against the Company remains stayed. Following a status conference with the Court on February 17, 2017, the Court issued several new pretrial orders in connection with the remaining claims in the MDL. On July 18, 2017, the Court issued an order dismissing all remaining “B3” claims in the MDL with prejudice, with the exception of certain claims specifically listed on an exhibit annexed to the order (the “Master MDL B3 Dismissal Order”). Mr. Dinwiddie, the claimant at issue in the Jambon Action, was not listed in this exhibit to the Master MDL B3 Dismissal Order, and so this claim against ORM and NRC has been dismissed with prejudice. Nathan Fitzgerald, the decedent in the Fitzgerald Action, was listed, and so this claim against the Company remains pending. The Company is unable to estimate the potential exposure, if any, resulting from these matters, to the extent they remain viable, but believes they are without merit and does not expect that they will have a material effect on its consolidated financial position, results of operations or cash flows. On February 18, 2011, Triton Asset Leasing GmbH, Transocean Holdings LLC, Transocean Offshore Deepwater Drilling Inc., and Transocean Deepwater Inc. (collectively “Transocean”) named ORM and NRC as third-party defendants in a Rule 14(c) Third-Party Complaint in Transocean’s own Limitation of Liability Act action, which is part of the overall MDL, tendering to ORM and NRC the claims in the referenced master complaint that have already been asserted against ORM and NRC. Transocean, Cameron International Corporation (“Cameron”), Halliburton Energy Services, Inc., and M-I L.L.C. (“M-I”) also filed cross-claims against ORM and NRC for contribution and tort indemnity should they be found liable for any damages in Transocean's Limitation of Liability Act action and ORM and NRC asserted counterclaims against those same parties for identical relief. The remainder of the aforementioned cross-claims in Transocean’s limitation action remain pending, although the Company believes that the potential exposure, if any, resulting from these matters has been reduced as a result of the various developments in the MDL, including the B3 Dismissal Order and Remaining Eleven Plaintiffs’ Dismissal Order, and does not expect that these matters will have a material effect on its consolidated financial position, results of operations or cash flows. On November 16, 2012, 668 individuals who served as beach clean-up workers in Escambia County, Florida during the Deepwater Horizon oil spill response commenced a civil action in the Circuit Court for the First Judicial Circuit of Florida, in and for Escambia County, Abney et al. v. Plant Performance Services, LLC et al. , No. 2012-CA-002947, in which they allege, among other things, that ORM and other defendants engaged in the contamination of Florida waters and beaches in violation of Florida Statutes Chapter 376 and injured the Plaintiffs by exposing them to dispersants during the course and scope of their employment. This case was removed to federal court and ultimately consolidated with the MDL on April 2, 2013. On April 22, 2013, a companion case to this matter was filed in the U.S. District Court for the Northern District of Florida, Abood et al. v. Plant Performance Services, LLC et al. , No. 3:13-CV-00284 (N.D. Fla.), which alleges identical allegations against the same parties but names an additional 174 Plaintiffs, all of whom served as clean-up workers in various Florida counties during the Deepwater Horizon oil spill response. This case was consolidated with the MDL on May 10, 2013. By court order, both of these matters were then stayed since they were consolidated with the MDL. The names of only a very small percentage of the claimants in these two matters appear to be listed on the exhibit to the Master MDL B3 Dismissal Order. The Company continues to evaluate the impact of the developments in the MDL, including the settlements discussed below, on these cases, but believes that the potential exposure, if any, resulting from these matters has been reduced as a result of these developments and does not expect that these matters will have a material effect on its consolidated financial position, results of operations or cash flows. Separately, on March 2, 2012, the Court announced that BP Exploration and BP America Production Company (“BP America”) (collectively “BP”) and the Plaintiffs had reached an agreement on the terms of two proposed class action settlements that will resolve, among other things, Plaintiffs’ economic loss claims and clean-up related claims against BP. Both settlements were granted final approval by the Court, all appeals have concluded, and the deadline for submitting claims with respect to both settlements has passed. Although neither the Company, ORM, nor NRC are parties to the settlement agreements, the Company, ORM, and NRC are listed as released parties on the releases accompanying both settlement agreements. Consequently, class members who did not file timely requests for exclusion will be barred from pursuing economic loss, property damage, personal injury, medical monitoring, and/or other released claims against the Company, ORM, and NRC. The Company believes these settlements have reduced the potential exposure, if any, in connection with the various cases relating to the Deepwater Horizon oil spill response and clean-up and continues to evaluate the settlements’ impacts on these cases. In the course of the Company’s business, it may agree to indemnify the counterparty to an agreement. If the indemnified party makes a successful claim for indemnification, the Company would be required to reimburse that party in accordance with the terms of the indemnification agreement. Indemnification agreements generally are subject to threshold amounts, specified claim periods and other restrictions and limitations. In connection with the SES Business Transaction, the Company remains contingently liable for certain obligations, including potential liabilities relating to work performed in connection with the Deepwater Horizon oil spill response. Pursuant to the agreement governing the sale, the Company’s potential liability to the purchaser may not exceed the consideration received by the Company for the SES Business Transaction. The Company is currently indemnified under contractual agreements with BP for the potential liabilities relating to work performed in connection with the Deepwater Horizon oil spill response. In the normal course of its business, the Company becomes involved in various other litigation matters including, among other things, claims by third parties for alleged property damages and personal injuries. Management has used estimates in determining the Company’s potential exposure to these matters and has recorded reserves in its financial statements related thereto where appropriate. It is possible that a change in the Company’s estimates of that exposure could occur, but the Company does not expect such changes in estimated costs would have a material effect on the Company’s consolidated financial position, results of operations or cash flows.

Segment Information

Segment Information	6 Months Ended
	Jun. 30, 2017
Segment Reporting [Abstract]
Segment Information	SEGMENT INFORMATION Accounting standards require public business enterprises to report information about each of their operating business segments that exceed certain quantitative thresholds or meet certain other reporting requirements. Operating business segments have been defined as components of an enterprise about which separate financial information is available and is evaluated regularly by the chief operating decision maker in deciding how to allocate resources and in assessing performance. Certain reclassifications of prior period information have been made to conform the current period’s reportable segment presentation as a result of the Company’s presentation of discontinued operations (see Notes 1 and 13). The Company’s basis of measurement of segment profit or loss is as previously defined in the Company’s Annual report on Form 10-K for the year ended December 31, 2016 . The Company’s segment presentation and basis of measurement of segment profit or loss are as previously described in the Company’s Annual Report on Form 10-K for the year ended December 31, 2016 . The following tables summarize the operating results, capital expenditures and assets of the Company’s reportable segments. Inland River Services $’000 Shipping Services $’000 Witt O’Brien’s $’000 Other $’000 Corporate and Eliminations $’000 Total $’000 For the three months ended June 30, 2017 Operating Revenues: External customers 37,644 72,023 6,008 116 — 115,791 Intersegment — — 53 — (53 ) — 37,644 72,023 6,061 116 (53 ) 115,791 Costs and Expenses: Operating 31,902 33,850 4,043 — (109 ) 69,686 Administrative and general 4,725 8,028 2,462 225 10,100 25,540 Depreciation and amortization 6,483 10,115 205 — 666 17,469 43,110 51,993 6,710 225 10,657 112,695 Gains on Asset Dispositions, Net 5,891 6 — — — 5,897 Operating Income (Loss) 425 20,036 (649 ) (109 ) (10,710 ) 8,993 Other Income (Expense): Derivative gains, net — — — — 16,897 16,897 Foreign currency gains (losses), net (1,630 ) 8 23 — 129 (1,470 ) Other, net — 421 — — 3 424 Equity in Earnings (Losses) of 50% or Less Owned Companies, Net of Tax (1,264 ) 5,621 (20 ) (2,004 ) — 2,333 Segment Profit (Loss) (2,469 ) 26,086 (646 ) (2,113 ) Other Income (Expense) not included in Segment Profit (Loss) (31,297 ) Less Equity Earnings included in Segment Profit (Loss) (2,333 ) Loss Before Taxes, Equity Earnings and Discontinued Operations (6,453 ) Inland River Services $’000 Shipping Services $’000 Witt O’Brien’s $’000 Other $’000 Corporate and Eliminations $’000 Total $’000 For the six months ended June 30, 2017 Operating Revenues: External customers 80,313 139,662 13,998 232 — 234,205 Intersegment — — 71 — (71 ) — 80,313 139,662 14,069 232 (71 ) 234,205 Costs and Expenses: Operating 64,471 71,204 9,415 — (192 ) 144,898 Administrative and general 8,517 15,116 5,681 379 18,725 48,418 Depreciation and amortization 13,075 19,276 407 — 1,430 34,188 86,063 105,596 15,503 379 19,963 227,504 Gains (Losses) on Asset Dispositions and Impairments, Net 6,124 (415 ) — — — 5,709 Operating Income (Loss) 374 33,651 (1,434 ) (147 ) (20,034 ) 12,410 Other Income (Expense): Derivative gains, net — — — — 19,727 19,727 Foreign currency gains (losses), net (262 ) 3 33 — 155 (71 ) Other, net — 59 — (300 ) 245 4 Equity in Earnings (Losses) of 50% or Less Owned Companies, Net of Tax (3,642 ) 6,657 137 (711 ) — 2,441 Segment Profit (Loss) (3,530 ) 40,370 (1,264 ) (1,158 ) Other Income (Expense) not included in Segment Profit (Loss) (18,631 ) Less Equity Earnings included in Segment Profit (Loss) (2,441 ) Income Before Taxes, Equity Earnings and Discontinued Operations 13,439 Capital Expenditures 22,754 58,018 60 — 155 80,987 As of June 30, 2017 Property and Equipment: Historical cost 421,117 888,563 1,227 — 29,493 1,340,400 Accumulated depreciation (170,162 ) (277,257 ) (892 ) — (19,614 ) (467,925 ) 250,955 611,306 335 — 9,879 872,475 Construction in progress 17,598 115,939 — — — 133,537 Net property and equipment 268,553 727,245 335 — 9,879 1,006,012 Investments, at Equity, and Advances to 50% or Less Owned Companies 66,956 48,486 663 58,001 — 174,106 Inventories 1,517 744 183 — — 2,444 Goodwill 2,391 1,852 28,506 — — 32,749 Intangible Assets 11,238 — 7,693 — — 18,931 Other current and long-term assets, excluding cash and near cash assets (1) 42,253 24,367 13,190 11,427 26,792 118,029 Segment Assets 392,908 802,694 50,570 69,428 Cash and near cash assets (1) 365,914 Discontinued Operations 55,700 Total Assets 1,773,885 ______________________ (1) Cash and near cash assets includes cash, cash equivalents, restricted cash, marketable securities and construction reserve funds. Inland River Services $’000 Shipping Services $’000 Witt O’Brien’s $’000 Other $’000 Corporate and Eliminations $’000 Total $’000 For the three months ended June 30, 2016 Operating Revenues: External customers 33,814 55,620 10,098 115 — 99,647 Intersegment — — 48 — (48 ) — 33,814 55,620 10,146 115 (48 ) 99,647 Costs and Expenses: Operating 27,446 30,269 6,427 — (115 ) 64,027 Administrative and general 3,777 7,337 3,475 174 6,598 21,361 Depreciation and amortization 6,254 7,415 448 — 926 15,043 37,477 45,021 10,350 174 7,409 100,431 Gains on Asset Dispositions, Net 2,580 6 — — — 2,586 Operating Income (Loss) (1,083 ) 10,605 (204 ) (59 ) (7,457 ) 1,802 Other Income (Expense): Derivative losses, net — — — — (2,574 ) (2,574 ) Foreign currency gains (losses), net 1,018 (6 ) (74 ) 1 (142 ) 797 Other, net (4 ) (928 ) — (6,723 ) 3 (7,652 ) Equity in Earnings (Losses) of 50% or Less Owned Companies, Net of Tax (1,677 ) (1,591 ) 100 (679 ) — (3,847 ) Segment Profit (Loss) (1,746 ) 8,080 (178 ) (7,460 ) Other Income (Expense) not included in Segment Profit (Loss) (25,923 ) Less Equity Losses included in Segment Profit (Loss) 3,847 Loss Before Taxes, Equity Losses and Discontinued Operations (33,550 ) Inland River Services $’000 Shipping Services $’000 Witt O’Brien’s $’000 Other $’000 Corporate and Eliminations $’000 Total $’000 For the six months ended June 30, 2016 Operating Revenues: External customers 73,428 112,675 18,346 250 — 204,699 Intersegment — — 84 — (84 ) — 73,428 112,675 18,430 250 (84 ) 204,699 Costs and Expenses: Operating 57,564 57,503 12,232 — (236 ) 127,063 Administrative and general 7,689 14,255 7,448 424 14,221 44,037 Depreciation and amortization 13,391 13,977 903 — 1,870 30,141 78,644 85,735 20,583 424 15,855 201,241 Gains (Losses) on Asset Dispositions, Net 3,185 — (2 ) — — 3,183 Operating Income (Loss) (2,031 ) 26,940 (2,155 ) (174 ) (15,939 ) 6,641 Other Income (Expense): Derivative losses, net — — — — (2,665 ) (2,665 ) Foreign currency gains (losses), net 2,455 (9 ) (100 ) — 48 2,394 Other, net (4 ) (927 ) — (6,723 ) 5 (7,649 ) Equity in Earnings (Losses) of 50% or Less Owned Companies, Net of Tax (4,455 ) (1,565 ) 186 (223 ) — (6,057 ) Segment Profit (Loss) (4,035 ) 24,439 (2,069 ) (7,120 ) Other Income (Expense) not included in Segment Profit (Loss) (49,461 ) Less Equity Losses included in Segment Profit (Loss) 6,057 Loss Before Taxes, Equity Losses and Discontinued Operations (50,740 ) Capital Expenditures 7,705 148,410 — — (125 ) 155,990 As of June 30, 2016 Property and Equipment: Historical cost 386,216 588,649 2,861 — 30,711 1,008,437 Accumulated depreciation (154,893 ) (244,910 ) (2,476 ) — (16,519 ) (418,798 ) 231,323 343,739 385 — 14,192 589,639 Construction in progress 7,663 290,582 — — (1,524 ) 296,721 Net property and equipment 238,986 634,321 385 — 12,668 886,360 Investments, at Equity, and Advances to 50% or Less Owned Companies 79,154 56,385 611 59,202 — 195,352 Inventories 1,824 799 99 — — 2,722 Goodwill 2,418 1,852 48,124 — — 52,394 Intangible Assets 5,521 — 18,595 — — 24,116 Other current and long-term assets, excluding cash and near cash assets (1) 45,428 27,477 14,983 7,961 3,803 99,652 Segment Assets 373,331 720,834 82,797 67,163 Cash and near cash assets (1) 539,897 Discontinued Operations 1,200,824 Total Assets 3,001,317 ______________________ (1) Cash and near cash assets includes cash, cash equivalents, restricted cash, marketable securities and construction reserve funds.

Discontinued Operations (Notes)

Discontinued Operations (Notes)	6 Months Ended
	Jun. 30, 2017
Discontinued Operations and Disposal Groups [Abstract]
Disposal Groups, Including Discontinued Operations, Disclosure [Text Block]	DISCONTINUED OPERATIONS The Company’s discontinued operations consist of SEACOR Marine and ICP and following the Spin-off and sale the Company has no continuing involvement in either of these business (see Note 1). As of June 30, 2017, the balances for discontinued operations included in the accompanying condensed consolidated balance sheets relate to ICP and consist primarily of working capital items including accounts receivable, inventories and accrued expenses, and property and equipment. Summarized selected operating results of the Company’s discontinued operations were as follows (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2017 2016 2017 2016 SEACOR Marine Operating Revenues $ 27,987 $ 57,271 $ 62,291 $ 117,150 Costs and Expenses: Operating 32,509 44,245 65,888 93,095 Administrative and general 17,856 11,929 29,682 24,327 Depreciation and amortization 9,678 15,254 22,181 30,092 60,043 71,428 117,751 147,514 Gains (Losses) on Asset Dispositions and Impairments, Net (600 ) (20,357 ) 4,219 (20,737 ) Operating Loss (32,656 ) (34,514 ) (51,241 ) (51,101 ) Other Income (Expense), Net (5,346 ) (6,702 ) 1,780 (11,682 ) Income Tax Benefit (9,509 ) (13,742 ) (12,931 ) (20,568 ) Equity in Earnings (Losses) of 50% or Less Owned Companies, Net of Tax 1,225 (3,315 ) 1,663 (1,154 ) Net Loss $ (27,268 ) $ (30,789 ) $ (34,867 ) $ (43,369 ) Net Loss Attributable to Noncontrolling Interests $ (1,688 ) $ (209 ) $ (1,892 ) $ (831 ) ICP Operating Revenues $ 39,676 $ 40,576 $ 78,061 $ 90,185 Costs and Expenses: Operating 40,205 36,153 76,306 82,442 Administrative and general 1,363 912 2,109 1,568 Depreciation and amortization 1,179 1,064 2,354 2,117 42,747 38,129 80,769 86,127 Operating Income (Loss) (3,071 ) 2,447 (2,708 ) 4,058 Other Income, Net 487 1,791 2,335 2,477 Income Tax Expense (Benefit) (668 ) 1,267 67 1,982 Net Income (Loss) $ (1,916 ) $ 2,971 $ (440 ) $ 4,553 Net Income (Loss) Attributable to Noncontrolling Interests $ (915 ) $ 984 $ (539 ) $ 1,406 Eliminations Operating Revenues $ (520 ) $ (456 ) $ (1,176 ) $ (1,068 ) Costs and Expenses: Operating (561 ) (543 ) (1,289 ) (1,250 ) Administrative and general (19 ) (27 ) (42 ) (53 ) (580 ) (570 ) (1,331 ) (1,303 ) Operating Income 60 114 155 235 Other Income, Net 795 884 1,738 1,917 Income Tax Expense 300 349 663 753 Net Income $ 555 $ 649 $ 1,230 $ 1,399 Loss from Discontinued Operations, Net of Tax $ (28,629 ) $ (27,169 ) $ (34,077 ) $ (37,417 )

Basis of Presentation and Acc20

Basis of Presentation and Accounting Policy (Policy)	6 Months Ended
	Jun. 30, 2017
Accounting Policies [Abstract]
Basis Of Consolidation	The condensed consolidated financial information for the three and six months ended June 30, 2017 and 2016 has been prepared by the Company and has not been audited by its independent registered certified public accounting firm. The condensed consolidated financial statements include the accounts of SEACOR Holdings Inc. and its consolidated subsidiaries. In the opinion of management, all adjustments (consisting of normal recurring adjustments) have been made to fairly present the Company’s financial position as of June 30, 2017 , its results of operations for the three and six months ended June 30, 2017 and 2016 , its comprehensive loss for the three and six months ended June 30, 2017 and 2016 , its changes in equity for the six months ended June 30, 2017 , and its cash flows for the six months ended June 30, 2017 and 2016 . Results of operations for the interim periods presented are not necessarily indicative of operating results for the full year or any future periods. Certain information and footnote disclosures normally included in financial statements prepared in accordance with generally accepted accounting principles in the United States have been condensed or omitted. These condensed consolidated financial statements should be read in conjunction with the financial statements and related notes thereto included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2016 . Unless the context otherwise indicates, any reference in this Quarterly Report on Form 10-Q to the “Company” refers to SEACOR Holdings Inc. and its consolidated subsidiaries and any reference in this Quarterly Report on Form 10-Q to “SEACOR” refers to SEACOR Holdings Inc without its consolidated subsidiaries. Capitalized terms used and not specifically defined herein have the same meaning given those terms in the Company's Annual report on Form 10-K for the year ended December 31, 2016 .
Discontinued Operations, Policy [Policy Text Block]	Discontinued Operations. On June 1, 2017, the Company completed the spin-off of SEACOR Marine Holdings Inc. (“SEACOR Marine”), the company that operated SEACOR’s Offshore Marine Services business segment (the “Spin-off”), by means of a dividend of all the issued and outstanding common stock of SEACOR Marine to SEACOR’s shareholders. SEACOR Marine is now an independent company whose common stock is listed on the New York Stock Exchange under the symbol “SMHI.” For all periods presented herein, the Company has reported the historical financial position, results of operations and cash flows of SEACOR Marine as discontinued operations (see Note 13). On July 3, 2017, the Company effected the sale of its 70% interest in Illinois Corn Processing LLC (“ICP”), the company that operated SEACOR’s Illinois Corn Processing business segment, through a merger transaction whereby the Company received $21.0 million in cash and issued a note to the buyer for $32.7 million , subject to a working capital adjustment, resulting in a third quarter gain of $11.6 million , net of tax. The principal amount of the promissory note accrues interest at a rate per annum equal to the three-month London Interbank Offered Rate (“LIBOR”) plus an applicable margin of 5% for the first three months, 8% for the next three months and 10% thereafter, and matures on January 3, 2019. The obligations of ICP under the promissory note are secured by the equity and substantially all of the assets of ICP. ICP operates a single-site alcohol manufacturing, storage and distribution facility producing alcohol used in the food, beverage, industrial and petrochemical end-markets. For all periods presented herein, the Company has reported the historical financial position, results of operations and cash flows of ICP as discontinued operations (see Note 13).
Subsequent Events [Text Block]	Subsequent Event. On July 3, 2017, International Shipholding Corporation (“ISH”) emerged from bankruptcy pursuant to its chapter 11 plan of reorganization (the “Plan”) that had been confirmed by the U.S. Bankruptcy Court for the Southern District of New York. Pursuant to the Plan, SEACOR Ocean Transport Inc., a wholly-owned subsidiary of the Company, acquired all of the equity of the reorganized ISH. ISH, through its subsidiaries, operates a diversified fleet of U.S. and foreign-flag vessels that provide worldwide and domestic maritime transportation services to commercial and governmental customers primarily under medium to long-term charters and contracts. Under the terms of the Plan, the Company paid $10.5 million in cash, converted $18.1 million of debtor in possession financing into equity and borrowed $25.0 million under a new credit facility that is secured by the assets and equity of ISH and is non-recourse to SEACOR and its subsidiaries other than ISH (see Note 4).
Revenue Recognition	Revenue Recognition. The Company recognizes revenue when it is realized or realizable and earned. Revenue is realized or realizable and earned when persuasive evidence of an arrangement exists, delivery has occurred or services have been rendered, the price to the buyer is fixed or determinable, and collectability is reasonably assured. Revenue that does not meet these criteria is deferred until the criteria are met.
Property, Plant and Equipment, Policy [Policy Text Block]	Property and Equipment. Equipment, stated at cost, is depreciated using the straight-line method over the estimated useful life of the asset to an estimated salvage value. With respect to each class of asset, the estimated useful life is based upon a newly built asset being placed into service and represents the time period beyond which it is typically not justifiable for the Company to continue to operate the asset in the same or similar manner. From time to time, the Company may acquire older assets that have already exceeded the Company’s useful life policy, in which case the Company depreciates such assets based on its best estimate of remaining useful life, typically the next survey or certification date. As of June 30, 2017 , the estimated useful life (in years) of each of the Company’s major categories of new equipment was as follows: Inland river dry-cargo and deck barges 20 Inland river liquid tank barges 25 Inland river towboats and harbor boats 25 Product tankers - U.S.-flag 25 Short-sea Container/RORO (1) vessels 20 Harbor and offshore tugs 25 Ocean liquid tank barges 25 Terminal facilities 20 ______________________ (1) Roll on/Roll off (“RORO”). Equipment maintenance and repair costs including the costs of routine overhauls, drydockings and inspections performed on vessels and equipment are charged to operating expense as incurred. Expenditures that extend the useful life or improve the marketing and commercial characteristics of equipment as well as major renewals and improvements to other properties are capitalized. Certain interest costs incurred during the construction of equipment are capitalized as part of the assets’ carrying values and are amortized over such assets’ estimated useful lives. During the six months ended June 30, 2017 , capitalized interest totaled $2.1 million .
Property, Plant and Equipment [Table Text Block]	As of June 30, 2017 , the estimated useful life (in years) of each of the Company’s major categories of new equipment was as follows: Inland river dry-cargo and deck barges 20 Inland river liquid tank barges 25 Inland river towboats and harbor boats 25 Product tankers - U.S.-flag 25 Short-sea Container/RORO (1) vessels 20 Harbor and offshore tugs 25 Ocean liquid tank barges 25 Terminal facilities 20 ______________________ (1) Roll on/Roll off (“RORO”).
Impairment or Disposal of Long-Lived Assets, Policy [Policy Text Block]	Impairment of Long-Lived Assets. The Company performs an impairment analysis of long-lived assets used in operations, including intangible assets, when indicators of impairment are present. These indicators may include a significant decrease in the market price of a long-lived asset or asset group, a significant adverse change in the extent or manner in which a long-lived asset or asset group is being used or in its physical condition, or a current period operating or cash flow loss combined with a history of operating or cash flow losses or a forecast that demonstrates continuing losses associated with the use of a long-lived asset or asset group. If the carrying values of the assets are not recoverable, as determined by the estimated undiscounted cash flows, the estimated fair value of the assets or asset groups are compared to their current carrying value and impairment charges are recorded if the carrying value exceeds fair value. The Company performs its testing on an asset or asset group basis. The Company’s estimates of undiscounted cash flows are highly subjective and actual results may vary from the Company’s estimates due to the uncertainty regarding projected financial performance. Generally, fair value is determined using valuation techniques, such as expected discounted cash flows or appraisals, as appropriate. During the six months ended June 30, 2017 , the Company recognized impairment charges of $0.4 million related to long-lived assets held for use. During the six months ended June 30, 2016 , the Company recognized no impairment charges related to long-lived assets held for use. Impairment of 50% or Less Owned Companies. Investments in 50% or less owned companies are reviewed periodically to assess whether there is an other-than-temporary decline in the carrying value of the investment. In its evaluation, the Company considers, among other items, recent and expected financial performance and returns, impairments recorded by the investee and the capital structure of the investee. When the Company determines the estimated fair value of an investment is below carrying value and the decline is other-than-temporary, the investment is written down to its estimated fair value. Actual results may vary from the Company’s estimates due to the uncertainty regarding projected financial performance, the severity and expected duration of declines in value, and the available liquidity in the capital markets to support the continuing operations of the investee, among other factors. Although the Company believes its assumptions and estimates are reasonable, the investee’s actual performance compared with the estimates could produce different results and lead to additional impairment charges in future periods. During the six months ended June 30, 2017 and 2016 , the Company did not recognize any impairment charges related to its 50% or less owned companies.
Income Tax, Policy [Policy Text Block]	Income Taxes. During the six months ended June 30, 2017 , the Company’s effective income tax rate of 1.7% was primarily due to taxes not provided on income attributable to noncontrolling interests (see Note 8).
Deferred Gains [Policy Text Block]	Deferred Gains. The Company has sold certain equipment to its 50% or less owned companies, entered into vessel sale-leaseback transactions with finance companies, and provided seller financing on sales of its equipment to third parties and its 50% or less owned companies. A portion of the gains realized from these transactions were deferred and recorded in deferred gains and other liabilities in the accompanying condensed consolidated balance sheets. Deferred gain activity related to these transactions for the six months ended June 30 was as follows (in thousands): 2017 2016 Balance at beginning of period $ 82,423 $ 92,610 Adjustments to deferred gains arising from asset sales 7,720 9,003 Amortization of deferred gains included in operating expenses as a reduction to rental expense (7,242 ) (7,367 ) Amortization of deferred gains included in gains on asset dispositions and impairments, net (1,210 ) (1,210 ) Other — (1,697 ) Balance at end of period $ 81,691 $ 91,339
Schedule Of Deferred Gain Activity [Table Text Block]	Deferred gain activity related to these transactions for the six months ended June 30 was as follows (in thousands): 2017 2016 Balance at beginning of period $ 82,423 $ 92,610 Adjustments to deferred gains arising from asset sales 7,720 9,003 Amortization of deferred gains included in operating expenses as a reduction to rental expense (7,242 ) (7,367 ) Amortization of deferred gains included in gains on asset dispositions and impairments, net (1,210 ) (1,210 ) Other — (1,697 ) Balance at end of period $ 81,691 $ 91,339
Accumulated Other Comprehensive Loss	Accumulated Other Comprehensive Loss. The components of accumulated other comprehensive loss were as follows (in thousands): SEACOR Holdings Inc. Stockholders’ Equity Noncontrolling Interests Foreign Currency Translation Adjustments Derivative Losses on Cash Flow Hedges, net Other Total Foreign Currency Translation Adjustments Derivative Losses on Cash Flow Hedges, net Other Other Comprehensive Income December 31, 2016 $ (11,593 ) $ 75 $ 4 $ (11,514 ) $ (1,613 ) $ (17 ) $ 3 Distribution of SEACOR Marine stock to shareholders 10,031 94 — 10,125 — — — Other comprehensive income (loss) 1,569 (260 ) (11 ) 1,298 153 13 (5 ) $ 1,459 Income tax (expense) benefit (549 ) 91 4 (454 ) — — — (454 ) Six Months Ended June 30, 2017 $ (542 ) $ — $ (3 ) $ (545 ) $ (1,460 ) $ (4 ) $ (2 ) $ 1,005
Earnings Per Common Share of SEACOR	Loss Per Share. Basic loss per common share of SEACOR is computed based on the weighted average number of common shares issued and outstanding during the relevant periods. Diluted loss per common share of SEACOR is computed based on the weighted average number of common shares issued and outstanding plus the effect of potentially dilutive securities through the application of the treasury stock and if-converted methods. Dilutive securities for this purpose assumes restricted stock grants have vested, common shares have been issued pursuant to the exercise of outstanding stock options and common shares have been issued pursuant to the conversion of all outstanding convertible notes. Computations of basic and diluted loss per common share of SEACOR were as follows (in thousands, except share data): Three Months Ended June 30, Six Months Ended June 30, Net Loss attributable to SEACOR Average O/S Shares Per Share Net Loss Attributable to SEACOR Average O/S Shares Per Share 2017 Basic Weighted Average Common Shares Outstanding $ (32,808 ) 17,207,831 $ (1.91 ) $ (28,725 ) 17,141,306 $ (1.68 ) Effect of Dilutive Share Awards: Options and Restricted Stock (1) — — — 299,055 Convertible Notes (2) — — — — Diluted Weighted Average Common Shares Outstanding $ (32,808 ) 17,207,831 $ (1.91 ) $ (28,725 ) 17,440,361 $ (1.65 ) 2016 Basic Weighted Average Common Shares Outstanding $ (55,159 ) 16,928,722 $ (3.26 ) $ (82,345 ) 16,873,045 $ (4.88 ) Effect of Dilutive Share Awards: Options and Restricted Stock (3) — — — — Convertible Notes (4) — — — — Diluted Weighted Average Common Shares Outstanding $ (55,159 ) 16,928,722 $ (3.26 ) $ (82,345 ) 16,873,045 $ (4.88 ) ______________________ (1) For the three and six months ended June 30, 2017 , diluted loss per common share of SEACOR excluded 2,644,489 and 1,563,901 , respectively, of certain share awards as the effect of their inclusion in the computation would be anti-dilutive. Diluted weighted average shares outstanding are calculated based on continuing operations. (2) For the three and six months ended June 30, 2017 , diluted loss per common share of SEACOR excluded 2,693,475 and 2,793,144 , respectively, of common shares issuable pursuant to the Company’s 2.5% Convertible Senior Notes and 2,801,147 and 2,801,147 , respectively, of common shares issuable pursuant to the Company’s 3.0% Convertible Senior Notes as the effect of their inclusion in the computation would be anti-dilutive. (3) For the three and six months ended June 30, 2016 , diluted loss per common share of SEACOR excluded 2,024,421 and 2,024,421 , respectively, of certain share awards as the effect of their inclusion in the computation would be anti-dilutive. (4) For the three and six months ended June 30, 2016 , diluted loss per common share of SEACOR excluded 2,975,847 and 3,177,620 , respectively, of common shares issuable pursuant to the Company’s 2.5% Convertible Senior Notes, 1,825,326 and 1,825,326 , respectively, of common shares issuable pursuant to the Company’s 3.0% Convertible Senior Notes and 2,243,500 and 2,243,500 , respectively, of common shares issuable pursuant to the Company’s 3.75% Subsidiary Convertible Senior Notes as the effect of their inclusion in the computation would be anti-dilutive.
Schedule of Weighted Average Number of Shares [Table Text Block]	Computations of basic and diluted loss per common share of SEACOR were as follows (in thousands, except share data): Three Months Ended June 30, Six Months Ended June 30, Net Loss attributable to SEACOR Average O/S Shares Per Share Net Loss Attributable to SEACOR Average O/S Shares Per Share 2017 Basic Weighted Average Common Shares Outstanding $ (32,808 ) 17,207,831 $ (1.91 ) $ (28,725 ) 17,141,306 $ (1.68 ) Effect of Dilutive Share Awards: Options and Restricted Stock (1) — — — 299,055 Convertible Notes (2) — — — — Diluted Weighted Average Common Shares Outstanding $ (32,808 ) 17,207,831 $ (1.91 ) $ (28,725 ) 17,440,361 $ (1.65 ) 2016 Basic Weighted Average Common Shares Outstanding $ (55,159 ) 16,928,722 $ (3.26 ) $ (82,345 ) 16,873,045 $ (4.88 ) Effect of Dilutive Share Awards: Options and Restricted Stock (3) — — — — Convertible Notes (4) — — — — Diluted Weighted Average Common Shares Outstanding $ (55,159 ) 16,928,722 $ (3.26 ) $ (82,345 ) 16,873,045 $ (4.88 ) ______________________ (1) For the three and six months ended June 30, 2017 , diluted loss per common share of SEACOR excluded 2,644,489 and 1,563,901 , respectively, of certain share awards as the effect of their inclusion in the computation would be anti-dilutive. Diluted weighted average shares outstanding are calculated based on continuing operations. (2) For the three and six months ended June 30, 2017 , diluted loss per common share of SEACOR excluded 2,693,475 and 2,793,144 , respectively, of common shares issuable pursuant to the Company’s 2.5% Convertible Senior Notes and 2,801,147 and 2,801,147 , respectively, of common shares issuable pursuant to the Company’s 3.0% Convertible Senior Notes as the effect of their inclusion in the computation would be anti-dilutive. (3) For the three and six months ended June 30, 2016 , diluted loss per common share of SEACOR excluded 2,024,421 and 2,024,421 , respectively, of certain share awards as the effect of their inclusion in the computation would be anti-dilutive. (4) For the three and six months ended June 30, 2016 , diluted loss per common share of SEACOR excluded 2,975,847 and 3,177,620 , respectively, of common shares issuable pursuant to the Company’s 2.5% Convertible Senior Notes, 1,825,326 and 1,825,326 , respectively, of common shares issuable pursuant to the Company’s 3.0% Convertible Senior Notes and 2,243,500 and 2,243,500 , respectively, of common shares issuable pursuant to the Company’s 3.75% Subsidiary Convertible Senior Notes as the effect of their inclusion in the computation would be anti-dilutive.
New Accounting Pronouncements	New Accounting Pronouncements. On May 28, 2014, the Financial Accounting Standards Board (“FASB”) issued a comprehensive new revenue recognition standard that will supersede nearly all existing revenue recognition guidance under generally accepted accounting principles in the United States. The core principal of the new standard is that a company will recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which the company expects to be entitled in exchange for those goods or services. The new standard is effective for annual and interim periods beginning after December 15, 2017 and early adoption is permitted. The Company will adopt the new standard on January 1, 2018 and expects to use the modified retrospective approach upon adoption. The Company is currently determining the impact, if any, the adoption of the new accounting standard will have on its consolidated financial position, results of operations or cash flows. Principal versus agent considerations of the new standard with respect to the Company’s vessel management services and pooling arrangements may result in a gross presentation of operating revenues and expenses compared with its current net presentation for results from managed and pooled third party equipment. On February 25, 2016, the FASB issued a comprehensive new leasing standard, which improves transparency and comparability among companies by requiring lessees to recognize a lease liability and a corresponding lease asset for virtually all lease contracts. It also requires additional disclosures about leasing arrangements. The new standard is effective for interim and annual periods beginning after December 15, 2018 and requires a modified retrospective approach to adoption. Early adoption is permitted. The Company has not yet determined what impact, if any, the adoption of the new standard will have on its consolidated financial position, results of operations or cash flows. On August 26, 2016, the FASB issued an amendment to the accounting standard which amends or clarifies guidance on classification of certain transactions in the statement of cash flows, including classification of proceeds from the settlement of insurance claims, debt prepayments, debt extinguishment costs and contingent consideration payments after a business combination. This new standard is effective for the Company as of January 1, 2018 and early adoption is permitted. The Company has not yet determined what impact, if any, the adoption of the new standard will have on its consolidated financial position, results of operations or cash flows. On October 24, 2016, the FASB issued a new accounting standard, which requires companies to account for the income tax effects of intercompany sales and transfers of assets other than inventory. The new standard is effective for interim and annual periods beginning after December 31, 2017 and requires a modified retrospective approach to adoption. The Company does not expect the adoption of the new standard will have a material impact on its consolidated financial position, results of operations or cash flows. On November 17, 2016, the FASB issued an amendment to the accounting standard which requires that restricted cash and restricted cash equivalents be included with cash and cash equivalents when reconciling the beginning-of-period and end-of-period total cash amounts shown on the statement of cash flows. The new standard is effective for fiscal years beginning after December 15, 2018, and interim periods within fiscal years beginning after December 15, 2019. Early adoption is permitted. The Company has not yet determined what impact, if any, the adoption of the new standard will have on its consolidated financial position, results of operations or cash flows. On January 26, 2017, the FASB issued an amendment to the accounting standard which simplified wording and removes step two of the goodwill impairment test. A goodwill impairment will now be the amount by which a reporting units carrying value exceeds its fair value, not to exceed the carrying amount of goodwill. The FASB also eliminated the requirements for any reporting unit with a zero or negative carrying amount to perform a qualitative assessment and, if it fails that qualitative test, to perform step two of the goodwill test. The new standard is effective for annual or interim goodwill impairment tests in fiscal years beginning after December 15, 2020, with early adoption permitted for interim or annual goodwill impairment tests on testing dates after January 1, 2017. The Company has not yet determined what impact, if any, the adoption of the new standard will have on its consolidated financial position, results of operations or cash flows.

Fair Value Measurements Fair Va

Fair Value Measurements Fair Value Measurements (Tables)	6 Months Ended
	Jun. 30, 2017
Fair Value Disclosures [Abstract]
Fair Value Measurements	FAIR VALUE MEASUREMENTS The fair value of an asset or liability is the price that would be received to sell an asset or transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. The Company utilizes a fair value hierarchy that maximizes the use of observable inputs and minimizes the use of unobservable inputs when measuring fair value and defines three levels of inputs that may be used to measure fair value. Level 1 inputs are quoted prices in active markets for identical assets or liabilities. Level 2 inputs are observable inputs other than quoted prices included in Level 1 that are observable for the asset or liability, either directly or indirectly, including quoted prices for similar assets or liabilities in active markets, quoted prices in markets that are not active, inputs other than quoted prices that are observable for the asset or liability, or inputs derived from observable market data. Level 3 inputs are unobservable inputs that are supported by little or no market activity and are significant to the fair value of the assets or liabilities. The Company’s financial assets and liabilities as of June 30, 2017 that are measured at fair value on a recurring basis were as follows (in thousands): Level 1 Level 2 Level 3 ASSETS Marketable securities (1) $ 75,071 $ — $ — Construction reserve funds 65,429 — — ______________________ (1) Marketable security losses, net include unrealized losses of $21.6 million and $21.6 million for the three months ended June 30, 2017 and 2016 , respectively, related to marketable security positions held by the Company as of June 30, 2017 . Marketable security losses, net include unrealized losses of $0.3 million and $43.3 million for the six months ended June 30, 2017 and 2016 , respectively, related to marketable security positions held by the Company as of June 30, 2017 . The estimated fair values of the Company’s other financial assets and liabilities as of June 30, 2017 were as follows (in thousands): Estimated Fair Value Carrying Amount Level 1 Level 2 Level 3 ASSETS Cash, cash equivalents and restricted cash $ 225,414 $ 225,414 $ — $ — Investments, at cost, in 50% or less owned companies (included in other assets) 4,300 see below Notes receivable from third parties (included in other receivables and other assets) 12,823 10,881 1,844 — LIABILITIES Long-term debt, including current portion (1) $ 741,187 $ — $ 746,682 $ — ______________________ (1) The estimated fair value includes the embedded conversion options on the Company’s 2.5% and 3.0% Convertible Senior Notes. The carrying value of cash, cash equivalents and restricted cash approximates fair value. The fair value of the Company’s long-term debt and notes receivable from third parties was estimated based upon quoted market prices or by using discounted cash flow analyses based on estimated current rates for similar types of arrangements. It was not practicable to estimate the fair value of certain of the Company’s investments, at cost, in 50% or less owned companies because of the lack of quoted market prices and the inability to estimate fair value without incurring excessive costs. Considerable judgment was required in developing certain of the estimates of fair value and, accordingly, the estimates presented herein are not necessarily indicative of the amounts that the Company could realize in a current market exchange.
Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis	The Company’s financial assets and liabilities as of June 30, 2017 that are measured at fair value on a recurring basis were as follows (in thousands): Level 1 Level 2 Level 3 ASSETS Marketable securities (1) $ 75,071 $ — $ — Construction reserve funds 65,429 — — ______________________ (1) Marketable security losses, net include unrealized losses of $21.6 million and $21.6 million for the three months ended June 30, 2017 and 2016 , respectively, related to marketable security positions held by the Company as of June 30, 2017 . Marketable security losses, net include unrealized losses of $0.3 million and $43.3 million for the six months ended June 30, 2017 and 2016 , respectively, related to marketable security positions held by the Company as of June 30, 2017 .
Estimated Fair Value Of Other Financial Assets And Liabilities	The estimated fair values of the Company’s other financial assets and liabilities as of June 30, 2017 were as follows (in thousands): Estimated Fair Value Carrying Amount Level 1 Level 2 Level 3 ASSETS Cash, cash equivalents and restricted cash $ 225,414 $ 225,414 $ — $ — Investments, at cost, in 50% or less owned companies (included in other assets) 4,300 see below Notes receivable from third parties (included in other receivables and other assets) 12,823 10,881 1,844 — LIABILITIES Long-term debt, including current portion (1) $ 741,187 $ — $ 746,682 $ — ______________________ (1) The estimated fair value includes the embedded conversion options on the Company’s 2.5% and 3.0% Convertible Senior Notes.

Noncontrolling Interests in S22

Noncontrolling Interests in Subsidiaries (Tables)	6 Months Ended
	Jun. 30, 2017
Noncontrolling Interest [Abstract]
Noncontrolling Interests in Subsidiaries [Table Text Block]	oncontrolling interests in the Company’s consolidated subsidiaries were as follows (in thousands): Noncontrolling Interests June 30, 2017 December 31, 2016 Inland River Services: Other 3.0 % – 51.8% $ 963 $ 980 Shipping Services: SEA-Vista 49% 118,798 106,054 Discontinued Operations 1.8 % – 50.0% 14,673 28,190 Other 5.0 % – 14.6% 151 152 $ 134,585 $ 135,376

Share Based Compensation (Table

Share Based Compensation (Tables)	6 Months Ended
	Jun. 30, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Share Based Compensation Plans	Transactions in connection with the Company’s share based compensation plans during the six months ended June 30, 2017 were as follows: Director stock awards granted 750 Employee Stock Purchase Plan (“ESPP”) shares issued 14,624 Restricted stock awards granted 144,750 Restricted stock awards canceled 2,117 Stock Option Activities: Outstanding as of December 31, 2016 1,639,865 Granted (1) 916,258 Exercised (138,648 ) Forfeited (3,374 ) Expired (21,442 ) Outstanding as of June 30, 2017 2,392,659 Shares available for future grants and ESPP purchases as of June 30, 2017 (2) 504,570 ______________________ (1) On June 2, 2017, the Company granted 846,353 stock options to existing option holders under make-whole provisions upon the Spin-off of SEACOR Marine. (2) Shares available for future grants and ESPP purchases were adjusted on June 2, 2017 to reflect the Spin-off of SEACOR Marine in accordance with make-whole provisions of the plans.

Commitments And Contingencies C

Commitments And Contingencies Capital Commitments (Tables)	6 Months Ended
	Jun. 30, 2017
Commitments and Contingencies Disclosure [Abstract]
Unrecorded Unconditional Purchase Obligations Disclosure [Table Text Block]	The Company's capital commitments as of June 30, 2017 by year of expected payment were as follows (in thousands): Remainder of 2017 2018 2019 Total Shipping Services $ 8,356 $ 2,259 $ — $ 10,615 Inland River Services 11,780 926 463 13,169 $ 20,136 $ 3,185 $ 463 $ 23,784 Shipping Services’ capital commitments included one U.S.-flag chemical and petroleum articulated tug-barge and two U.S.-flag harbor tugs. Inland River Services’ capital commitments included two inland river towboats and other equipment and improvements.

Segment Information Segment Inf

Segment Information Segment Information (Tables)	6 Months Ended
	Jun. 30, 2017
Segment Reporting [Abstract]
Operating Results, Capital Expenditures And Assets By Reporting Segment	The following tables summarize the operating results, capital expenditures and assets of the Company’s reportable segments. Inland River Services $’000 Shipping Services $’000 Witt O’Brien’s $’000 Other $’000 Corporate and Eliminations $’000 Total $’000 For the three months ended June 30, 2017 Operating Revenues: External customers 37,644 72,023 6,008 116 — 115,791 Intersegment — — 53 — (53 ) — 37,644 72,023 6,061 116 (53 ) 115,791 Costs and Expenses: Operating 31,902 33,850 4,043 — (109 ) 69,686 Administrative and general 4,725 8,028 2,462 225 10,100 25,540 Depreciation and amortization 6,483 10,115 205 — 666 17,469 43,110 51,993 6,710 225 10,657 112,695 Gains on Asset Dispositions, Net 5,891 6 — — — 5,897 Operating Income (Loss) 425 20,036 (649 ) (109 ) (10,710 ) 8,993 Other Income (Expense): Derivative gains, net — — — — 16,897 16,897 Foreign currency gains (losses), net (1,630 ) 8 23 — 129 (1,470 ) Other, net — 421 — — 3 424 Equity in Earnings (Losses) of 50% or Less Owned Companies, Net of Tax (1,264 ) 5,621 (20 ) (2,004 ) — 2,333 Segment Profit (Loss) (2,469 ) 26,086 (646 ) (2,113 ) Other Income (Expense) not included in Segment Profit (Loss) (31,297 ) Less Equity Earnings included in Segment Profit (Loss) (2,333 ) Loss Before Taxes, Equity Earnings and Discontinued Operations (6,453 ) Inland River Services $’000 Shipping Services $’000 Witt O’Brien’s $’000 Other $’000 Corporate and Eliminations $’000 Total $’000 For the six months ended June 30, 2017 Operating Revenues: External customers 80,313 139,662 13,998 232 — 234,205 Intersegment — — 71 — (71 ) — 80,313 139,662 14,069 232 (71 ) 234,205 Costs and Expenses: Operating 64,471 71,204 9,415 — (192 ) 144,898 Administrative and general 8,517 15,116 5,681 379 18,725 48,418 Depreciation and amortization 13,075 19,276 407 — 1,430 34,188 86,063 105,596 15,503 379 19,963 227,504 Gains (Losses) on Asset Dispositions and Impairments, Net 6,124 (415 ) — — — 5,709 Operating Income (Loss) 374 33,651 (1,434 ) (147 ) (20,034 ) 12,410 Other Income (Expense): Derivative gains, net — — — — 19,727 19,727 Foreign currency gains (losses), net (262 ) 3 33 — 155 (71 ) Other, net — 59 — (300 ) 245 4 Equity in Earnings (Losses) of 50% or Less Owned Companies, Net of Tax (3,642 ) 6,657 137 (711 ) — 2,441 Segment Profit (Loss) (3,530 ) 40,370 (1,264 ) (1,158 ) Other Income (Expense) not included in Segment Profit (Loss) (18,631 ) Less Equity Earnings included in Segment Profit (Loss) (2,441 ) Income Before Taxes, Equity Earnings and Discontinued Operations 13,439 Capital Expenditures 22,754 58,018 60 — 155 80,987 As of June 30, 2017 Property and Equipment: Historical cost 421,117 888,563 1,227 — 29,493 1,340,400 Accumulated depreciation (170,162 ) (277,257 ) (892 ) — (19,614 ) (467,925 ) 250,955 611,306 335 — 9,879 872,475 Construction in progress 17,598 115,939 — — — 133,537 Net property and equipment 268,553 727,245 335 — 9,879 1,006,012 Investments, at Equity, and Advances to 50% or Less Owned Companies 66,956 48,486 663 58,001 — 174,106 Inventories 1,517 744 183 — — 2,444 Goodwill 2,391 1,852 28,506 — — 32,749 Intangible Assets 11,238 — 7,693 — — 18,931 Other current and long-term assets, excluding cash and near cash assets (1) 42,253 24,367 13,190 11,427 26,792 118,029 Segment Assets 392,908 802,694 50,570 69,428 Cash and near cash assets (1) 365,914 Discontinued Operations 55,700 Total Assets 1,773,885 ______________________ (1) Cash and near cash assets includes cash, cash equivalents, restricted cash, marketable securities and construction reserve funds. Inland River Services $’000 Shipping Services $’000 Witt O’Brien’s $’000 Other $’000 Corporate and Eliminations $’000 Total $’000 For the three months ended June 30, 2016 Operating Revenues: External customers 33,814 55,620 10,098 115 — 99,647 Intersegment — — 48 — (48 ) — 33,814 55,620 10,146 115 (48 ) 99,647 Costs and Expenses: Operating 27,446 30,269 6,427 — (115 ) 64,027 Administrative and general 3,777 7,337 3,475 174 6,598 21,361 Depreciation and amortization 6,254 7,415 448 — 926 15,043 37,477 45,021 10,350 174 7,409 100,431 Gains on Asset Dispositions, Net 2,580 6 — — — 2,586 Operating Income (Loss) (1,083 ) 10,605 (204 ) (59 ) (7,457 ) 1,802 Other Income (Expense): Derivative losses, net — — — — (2,574 ) (2,574 ) Foreign currency gains (losses), net 1,018 (6 ) (74 ) 1 (142 ) 797 Other, net (4 ) (928 ) — (6,723 ) 3 (7,652 ) Equity in Earnings (Losses) of 50% or Less Owned Companies, Net of Tax (1,677 ) (1,591 ) 100 (679 ) — (3,847 ) Segment Profit (Loss) (1,746 ) 8,080 (178 ) (7,460 ) Other Income (Expense) not included in Segment Profit (Loss) (25,923 ) Less Equity Losses included in Segment Profit (Loss) 3,847 Loss Before Taxes, Equity Losses and Discontinued Operations (33,550 ) Inland River Services $’000 Shipping Services $’000 Witt O’Brien’s $’000 Other $’000 Corporate and Eliminations $’000 Total $’000 For the six months ended June 30, 2016 Operating Revenues: External customers 73,428 112,675 18,346 250 — 204,699 Intersegment — — 84 — (84 ) — 73,428 112,675 18,430 250 (84 ) 204,699 Costs and Expenses: Operating 57,564 57,503 12,232 — (236 ) 127,063 Administrative and general 7,689 14,255 7,448 424 14,221 44,037 Depreciation and amortization 13,391 13,977 903 — 1,870 30,141 78,644 85,735 20,583 424 15,855 201,241 Gains (Losses) on Asset Dispositions, Net 3,185 — (2 ) — — 3,183 Operating Income (Loss) (2,031 ) 26,940 (2,155 ) (174 ) (15,939 ) 6,641 Other Income (Expense): Derivative losses, net — — — — (2,665 ) (2,665 ) Foreign currency gains (losses), net 2,455 (9 ) (100 ) — 48 2,394 Other, net (4 ) (927 ) — (6,723 ) 5 (7,649 ) Equity in Earnings (Losses) of 50% or Less Owned Companies, Net of Tax (4,455 ) (1,565 ) 186 (223 ) — (6,057 ) Segment Profit (Loss) (4,035 ) 24,439 (2,069 ) (7,120 ) Other Income (Expense) not included in Segment Profit (Loss) (49,461 ) Less Equity Losses included in Segment Profit (Loss) 6,057 Loss Before Taxes, Equity Losses and Discontinued Operations (50,740 ) Capital Expenditures 7,705 148,410 — — (125 ) 155,990 As of June 30, 2016 Property and Equipment: Historical cost 386,216 588,649 2,861 — 30,711 1,008,437 Accumulated depreciation (154,893 ) (244,910 ) (2,476 ) — (16,519 ) (418,798 ) 231,323 343,739 385 — 14,192 589,639 Construction in progress 7,663 290,582 — — (1,524 ) 296,721 Net property and equipment 238,986 634,321 385 — 12,668 886,360 Investments, at Equity, and Advances to 50% or Less Owned Companies 79,154 56,385 611 59,202 — 195,352 Inventories 1,824 799 99 — — 2,722 Goodwill 2,418 1,852 48,124 — — 52,394 Intangible Assets 5,521 — 18,595 — — 24,116 Other current and long-term assets, excluding cash and near cash assets (1) 45,428 27,477 14,983 7,961 3,803 99,652 Segment Assets 373,331 720,834 82,797 67,163 Cash and near cash assets (1) 539,897 Discontinued Operations 1,200,824 Total Assets 3,001,317 ______________________ (1) Cash and near cash assets includes cash, cash equivalents, restricted cash, marketable securities and construction reserve funds.

Discontinued Operations (Tables

Discontinued Operations (Tables)	6 Months Ended
	Jun. 30, 2017
Discontinued Operations and Disposal Groups [Abstract]
Disposal Groups, Including Discontinued Operations [Table Text Block]	Summarized selected operating results of the Company’s discontinued operations were as follows (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2017 2016 2017 2016 SEACOR Marine Operating Revenues $ 27,987 $ 57,271 $ 62,291 $ 117,150 Costs and Expenses: Operating 32,509 44,245 65,888 93,095 Administrative and general 17,856 11,929 29,682 24,327 Depreciation and amortization 9,678 15,254 22,181 30,092 60,043 71,428 117,751 147,514 Gains (Losses) on Asset Dispositions and Impairments, Net (600 ) (20,357 ) 4,219 (20,737 ) Operating Loss (32,656 ) (34,514 ) (51,241 ) (51,101 ) Other Income (Expense), Net (5,346 ) (6,702 ) 1,780 (11,682 ) Income Tax Benefit (9,509 ) (13,742 ) (12,931 ) (20,568 ) Equity in Earnings (Losses) of 50% or Less Owned Companies, Net of Tax 1,225 (3,315 ) 1,663 (1,154 ) Net Loss $ (27,268 ) $ (30,789 ) $ (34,867 ) $ (43,369 ) Net Loss Attributable to Noncontrolling Interests $ (1,688 ) $ (209 ) $ (1,892 ) $ (831 ) ICP Operating Revenues $ 39,676 $ 40,576 $ 78,061 $ 90,185 Costs and Expenses: Operating 40,205 36,153 76,306 82,442 Administrative and general 1,363 912 2,109 1,568 Depreciation and amortization 1,179 1,064 2,354 2,117 42,747 38,129 80,769 86,127 Operating Income (Loss) (3,071 ) 2,447 (2,708 ) 4,058 Other Income, Net 487 1,791 2,335 2,477 Income Tax Expense (Benefit) (668 ) 1,267 67 1,982 Net Income (Loss) $ (1,916 ) $ 2,971 $ (440 ) $ 4,553 Net Income (Loss) Attributable to Noncontrolling Interests $ (915 ) $ 984 $ (539 ) $ 1,406 Eliminations Operating Revenues $ (520 ) $ (456 ) $ (1,176 ) $ (1,068 ) Costs and Expenses: Operating (561 ) (543 ) (1,289 ) (1,250 ) Administrative and general (19 ) (27 ) (42 ) (53 ) (580 ) (570 ) (1,331 ) (1,303 ) Operating Income 60 114 155 235 Other Income, Net 795 884 1,738 1,917 Income Tax Expense 300 349 663 753 Net Income $ 555 $ 649 $ 1,230 $ 1,399 Loss from Discontinued Operations, Net of Tax $ (28,629 ) $ (27,169 ) $ (34,077 ) $ (37,417 )

Basis of Presentation and Acc27

Basis of Presentation and Accounting Policies Discontinued Operations (Details) - Subsequent Event [Member] - Illinois Corn Processing LLC [Member] - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Dec. 31, 2018	Jul. 03, 2017
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Discontinued Operation, Gain (Loss) on Disposal of Discontinued Operation, Net of Tax		$ 11.6
Noncontrolling Interest, Ownership Percentage by Parent				70.00%
Proceeds from Divestiture of Businesses		21
Proceeds from Issuance of Secured Debt		$ 32.7
London Interbank Offered Rate (LIBOR) [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Debt Instrument, Basis Spread on Variable Rate	8.00%	5.00%	10.00%

Basis of Presentation and Acc28

Basis of Presentation and Accounting Policies Subsequent Event (Details) - ISH [Member] - Subsequent Event [Member] - USD ($) $ in Millions	3 Months Ended
	Sep. 30, 2017	Jul. 03, 2017
Subsequent Event [Line Items]
Payments to Acquire Businesses, Gross	$ 10.5
Debt Conversion, Converted Instrument, Amount	$ 18.1
Line of Credit Facility, Maximum Borrowing Capacity		$ 25

Basis of Presentation and Acc29

Basis of Presentation and Accounting Policies Property and Equipment (Details) $ in Millions	6 Months Ended
	Jun. 30, 2017USD ($)
Property, Plant and Equipment [Line Items]
Capitalized Interest Costs, Including Allowance for Funds Used During Construction	$ 2.1
Inland River Dry Cargo and Deck Barges [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	20 years
Inland River Liquid Tank Barges [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	25 years
Inland River Towboats [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	25 years
U.S.-flag Product Tankers [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	25 years
Short-sea Container/RORO Vessels [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	20 years
Harbor and Offshore Tugs [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	25 years
Ocean Liquid Tank Barge [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	25 years
Terminal And Manufacturing Facilities [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	20 years

Basis of Presentation and Acc30

Basis of Presentation and Accounting Policies Impairments of Long-Lived Assets (Details) $ in Millions	6 Months Ended
	Jun. 30, 2017USD ($)
Property, Plant and Equipment [Abstract]
Asset Impairment Charges	$ 0.4

Basis of Presentation and Acc31

Basis of Presentation and Accounting Policies Income Taxes (Details)	6 Months Ended
	Jun. 30, 2017
Income Tax Disclosure [Abstract]
Effective Income Tax Rate Reconciliation, Percent	1.70%

Basis of Presentation and Acc32

Basis of Presentation and Accounting Policies Deferred Gains (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016	Dec. 31, 2015
Deferred Gains	$ 81,691	$ 91,339	$ 82,423	$ 92,610
Amortization of Deferred Gains	0	1,697
Operating Expense [Member]
Amortization of Deferred Gains	7,242	7,367
Gain (Loss) on Asset Dispositions and Impairments, Net [Member]
Amortization of Deferred Gains	$ 1,210	$ 1,210

Basis of Presentation and Acc33

Basis of Presentation and Accounting Policies Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Accumulated Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Net of Tax	$ (542)		$ (542)		$ (11,593)
Accumulated Other Comprehensive Income (Loss), Cumulative Changes in Net Gain (Loss) from Cash Flow Hedges, Effect Net of Tax	0		0		75
Accumulated Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net of Tax	(3)		(3)		4
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, before Tax, Portion Attributable to Parent			1,569
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, before Tax, Portion Attributable to Parent			(260)
Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Adjustment, before Tax, Portion Attributable to Parent			(11)
Other Comprehensive Income (Loss), before Tax, Portion Attributable to Parent			1,298
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax, Portion Attributable to Noncontrolling Interest			153
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, before Tax, Portion Attributable to Noncontrolling Interest			13
Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax, Portion Attributable to Noncontrolling Interest			(5)
Other Comprehensive Income (Loss), before Tax	609	$ (5,208)	1,459	$ (8,687)
Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Tax, Portion Attributable to Parent			(549)
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Tax, Portion Attributable to Parent			91
Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Tax, Portion Attributable to Parent			4
Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent			(454)
Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Tax, Portion Attributable to Noncontrolling Interest			0
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Tax, Portion Attributable to Noncontrolling Interest			0
Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Tax, Portion Attributable to Noncontrolling Interest			0
Other Comprehensive Income (Loss), Tax	190	(1,640)	454	(2,794)
Accumulated other comprehensive loss, net of tax	(545)		(545)		(11,514)
Other Comprehensive Income (Loss), Net of Tax	419	$ (3,568)	1,005	$ (5,893)
Non-Controlling Interests In Subsidiaries [Member]
Accumulated Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Net of Tax	(1,460)		(1,460)		(1,613)
Accumulated Other Comprehensive Income (Loss), Cumulative Changes in Net Gain (Loss) from Cash Flow Hedges, Effect Net of Tax	(4)		(4)		(17)
Accumulated Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net of Tax	$ (2)		(2)		$ 3
Other Comprehensive Income (Loss), Net of Tax			$ 161

Basis of Presentation and Acc34

Basis of Presentation and Accounting Policies Earning Per Common Share (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Mar. 31, 2017
Net income attributable to SEACOR Holdings Inc.	$ (32,808,000)	$ (55,159,000)	$ (28,725,000)	$ (82,345,000)
Dilutive Securities, Effect on Basic Earnings Per Share, Options and Restrictive Stock Units	0	0	0	0
Dilutive Securities, Effect on Basic Earnings Per Share, Dilutive Convertible Securities	0	0	0	0
Net Income (Loss) Available to Common Stockholders, Diluted	$ (32,808,000)	$ (55,159,000)	$ (28,725,000)	$ (82,345,000)
Weighted Average Number of Shares Outstanding, Basic	17,207,831	16,928,722	17,141,306	16,873,045
Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements	0	0	299,055	0
Incremental Common Shares Attributable to Dilutive Effect of Conversion of Debt Securities	0	0	0	0
Weighted Average Number of Shares Outstanding, Diluted	17,207,831	16,928,722	17,440,361	16,873,045
Basic Earnings (Loss) Per Common Share of SEACOR Holdings Inc.	$ (1.91)	$ (3.26)	$ (1.68)	$ (4.88)
Diluted Earnings (Loss) Per Common Share of SEACOR Holdings Inc.	$ (1.91)	$ (3.26)	$ (1.65)	$ (4.88)
Stock Compensation Plan [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	2,644,489	2,024,421	1,563,901	2,024,421
Three Point Seven Five Percentage Convertible Notes [Member]
Debt Instrument, Interest Rate, Stated Percentage	3.75%		3.75%
Three Point Seven Five Percentage Convertible Notes [Member] | Convertible Debt Securities [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount		2,243,500		2,243,500
Three Point Zero Percentage Convertible Notes [Member]
Incremental Common Shares Attributable to Dilutive Effect of Conversion of Debt Securities			2,801,147
Debt Instrument, Interest Rate, Stated Percentage	3.00%		3.00%		3.00%
Three Point Zero Percentage Convertible Notes [Member] | Convertible Debt Securities [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	2,801,147	1,825,326	2,801,147	1,825,326
Two Point Five Percentage Convertible Notes [Member]
Incremental Common Shares Attributable to Dilutive Effect of Conversion of Debt Securities			2,001,993
Debt Instrument, Interest Rate, Stated Percentage	2.50%		2.50%		2.50%
Two Point Five Percentage Convertible Notes [Member] | Convertible Debt Securities [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	2,693,475	2,975,847	2,793,144	3,177,620

Equipment Acquisitions, Dispo35

Equipment Acquisitions, Dispositions and Depreciation and Impairment Policies (Narrative) (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2017USD ($)equipment	Jun. 30, 2016USD ($)
Property, Plant and Equipment [Line Items]
Payments to Acquire Property, Plant, and Equipment	$ 80,987	$ 155,990
Sales Price Of Equipment	19,800
Gain (Loss) on Disposition of Property Plant Equipment	13,000
Increase (Decrease) in Deferred Charges	7,720	9,003
Sale Leaseback Transaction, Net Proceeds, Investing Activities	12,500
Amortization Of Deferred Gains Included In Gains On Asset Dispositions And Impairments, Net	$ 0	1,697
Inland River Liquid Tank Barges [Member]
Property, Plant and Equipment [Line Items]
Number of Equipment Acquired | equipment	1
Inland River Towboat [Member]
Property, Plant and Equipment [Line Items]
Number of Equipment Acquired | equipment	1
Number Of Equipments Sold | equipment	1
U.S.-flag Product Tankers [Member]
Property, Plant and Equipment [Line Items]
Number of Equipment Acquired | equipment	1
U.S.-flag Harbor Tugs [Member]
Property, Plant and Equipment [Line Items]
Number of Equipment Acquired | equipment	1
Foreign-flag Harbor Tugs [Member]
Property, Plant and Equipment [Line Items]
Number of Equipment Acquired | equipment	2
Inland River Dry Cargo Barges [Member]
Property, Plant and Equipment [Line Items]
Number Of Equipments Sold | equipment	50
Sale Leaseback Transaction, Description of Asset(s)	50
Sale Leaseback Transaction, Lease Terms	84
Inland River Specialty Barges [Member]
Property, Plant and Equipment [Line Items]
Number of Equipments Removed from Service | equipment	(1)
Gain (Loss) on Asset Dispositions and Impairments, Net [Member]
Property, Plant and Equipment [Line Items]
Gain (Loss) on Disposition of Property Plant Equipment	$ 5,300
Amortization Of Deferred Gains Included In Gains On Asset Dispositions And Impairments, Net	1,210	$ 1,210
Gain (Loss) on Asset Dispositions and Impairments, Net [Member] | Inland River Specialty Barges [Member]
Property, Plant and Equipment [Line Items]
Gain (Loss) on Disposition of Property Plant Equipment	$ (400)

Investments, At Equity, And A36

Investments, At Equity, And Advances To 50% Or Less Owned Companies (Narrative) (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Schedule Of Equity Method Investments [Line Items]
Return of investments and advances from 50% or less owned companies	$ 3,940	$ 7,559
SCFCo Holdings [Member]
Schedule Of Equity Method Investments [Line Items]
Partners' Capital Account, Contributions	3,000
Payments for Advance to Affiliate	500
Proceeds from Collection of Advance to Affiliate	(500)
Outstanding Working Capital Advances At End Of Period	29,000
Trailer Bridge Inc [Member]
Schedule Of Equity Method Investments [Line Items]
Payments for Advance to Affiliate	2,000
Outstanding Working Capital Advances At End Of Period	6,000
Seajon [Member]
Schedule Of Equity Method Investments [Line Items]
Proceeds from Equity Method Investment, Dividends or Distributions, Return of Capital	3,400
Return of investments and advances from 50% or less owned companies	$ 12,500
Kotug [Member]
Schedule Of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	50.00%
Partners' Capital Account, Contributions	$ 300
VA&E [Member]
Schedule Of Equity Method Investments [Line Items]
Outstanding Working Capital Advances At End Of Period	7,300
Line of Credit Facility, Maximum Borrowing Capacity	3,500
Proceeds from Unsecured Lines of Credit	3,500
Avion Pacific Limited [Member]
Schedule Of Equity Method Investments [Line Items]
Payments for Advance to Affiliate	1,000
Outstanding Working Capital Advances At End Of Period	4,000
Subordinated Debt [Member] | VA&E [Member]
Schedule Of Equity Method Investments [Line Items]
Outstanding Working Capital Advances At End Of Period	$ 3,500

Long-Term Debt (Details)

Long-Term Debt (Details) $ / shares in Units, $ in Thousands	3 Months Ended			6 Months Ended
	Sep. 30, 2017USD ($)	Jun. 30, 2017USD ($)$ / sharesshares	Jun. 30, 2016USD ($)shares	Jun. 30, 2017USD ($)$ / sharesshares	Jun. 30, 2016USD ($)shares	Jul. 03, 2017USD ($)	Mar. 31, 2017	Dec. 31, 2016$ / shares
Debt Instrument [Line Items]
Common Stock, par value | $ / shares		$ 0.01		$ 0.01				$ 0.01
Stock Repurchase Program, Remaining Authorized Repurchase Amount		$ 90,700		$ 90,700
Letters of Credit Outstanding, Amount		$ 26,200		$ 26,200
Incremental Common Shares Attributable to Dilutive Effect of Conversion of Debt Securities | shares		0	0	0	0
Gain (Loss) on Extinguishment of Debt		$ (97)	$ 1,615	$ (97)	$ 4,838
Seven Point Three Seven Five Percentage Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		7.375%		7.375%
Debt Instrument, Repurchased Face Amount		$ 7,600		$ 7,600
Debt Instrument, Repurchase Amount		7,700		7,700
Gain (Loss) on Extinguishment of Debt				(200)
Senior Notes, Noncurrent		$ 153,100		$ 153,100
Three Point Zero Percentage Convertible Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		3.00%		3.00%			3.00%
Debt Instrument, Convertible, Conversion Ratio				12.1789
Incremental Common Shares Attributable to Dilutive Effect of Conversion of Debt Securities | shares				2,801,147
Two Point Five Percentage Convertible Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		2.50%		2.50%			2.50%
Debt Instrument, Repurchased Face Amount		$ 48,400		$ 48,400
Convertible Debt		108,700		$ 108,700
Debt Instrument, Convertible, Conversion Ratio				18.4176
Incremental Common Shares Attributable to Dilutive Effect of Conversion of Debt Securities | shares				2,001,993
Debt Instrument, Repurchase Amount		48,600		$ 48,600
Gain (Loss) on Extinguishment of Debt				100
Other Debt Obligations [Member]
Debt Instrument [Line Items]
Repayments of long-term debt				200
SEACOR Marine Holdings Inc. [Member]
Debt Instrument [Line Items]
Letters of Credit Outstanding, Amount		16,700		16,700
Guarantor Obligations, Maximum Exposure, Undiscounted		90,900		90,900
Guaranty Fee Income		200	$ 200	400	$ 400
Sea-Vista [Member] | Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Proceeds from Lines of Credit				27,900
Repayments of Lines of Credit				30,900
Line of Credit Facility, Current Borrowing Capacity		17,000		17,000
Sea-Vista [Member] | Term A-1 Loan [Member]
Debt Instrument [Line Items]
Repayments of long-term debt				1,800
Subsequent Event [Member] | Two Point Five Percentage Convertible Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Repurchased Face Amount	$ 6,500
Debt Instrument, Repurchase Amount	6,500
Subsequent Event [Member] | Sea-Vista [Member] | Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Proceeds from Lines of Credit	11,000
Subsequent Event [Member] | ISH [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity						$ 25,000
Subsequent Event [Member] | ISH [Member] | Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Debt Instrument, Unused Borrowing Capacity, Amount						5,000
Proceeds from Lines of Credit	5,000
Repayments of Lines of Credit	3,500
Subsequent Event [Member] | ISH [Member] | ISH Term Loan [Member]
Debt Instrument [Line Items]
Debt Instrument, Unused Borrowing Capacity, Amount						$ 20,000
Repayments of long-term debt	6,500
Proceeds from Issuance of Debt	20,000
Minimum [Member] | Subsequent Event [Member] | ISH [Member]
Debt Instrument [Line Items]
Debt Instrument, Mandatory Prepayment Balance	$ 700
Long-term Debt [Member] | Two Point Five Percentage Convertible Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Repurchase Amount		47,400		47,400
Additional Paid-In Capital [Member] | Two Point Five Percentage Convertible Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Repurchase Amount		$ 1,200		$ 1,200

Derivative Instruments And He38

Derivative Instruments And Hedging Strategies (Recognized Gains (Losses) On Derivative Instruments Not Designated As Hedging Instruments) (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Derivative [Line Items]
Derivative gains (losses), net	$ 19,727	$ (2,665)
Forward Currency Exchange, Option And Future Contracts [Member]
Derivative [Line Items]
Derivative gains (losses), net	291	(107)
Commodity swap, option and future contracts, exchange traded
Derivative [Line Items]
Derivative gains (losses), net	0	2
Three Point Seven Five Percentage Convertible Notes [Member]
Derivative [Line Items]
Embedded Derivative, Gain on Embedded Derivative	$ 19,436	$ (2,560)
Seajon [Member] | Cash Flow Hedging [Member]
Derivative [Line Items]
Fixed interest rate	2.79%

Fair Value Measurements (Financ

Fair Value Measurements (Financial Assets And Liabilities Measured At Fair Value On Recurring Basis) (Details) - USD ($) $ in Thousands	3 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Construction Reserve Funds	$ 65,429		$ 75,753
Marketable security gains (losses), net	(21,600)	$ (21,600)
Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	75,071
Construction Reserve Funds	65,429
Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	0
Construction Reserve Funds	0
Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	0
Construction Reserve Funds	$ 0

Fair Value Measurements (Estima

Fair Value Measurements (Estimated Fair Value Of Other Financial Assets And Liabilities) (Details) - USD ($)	Jun. 30, 2017	Mar. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash, cash equivalents and restricted cash	$ 225,414,000
Investments, at cost, in 50% or less owned companies (included in other assets), Carrying Amount	4,300,000
Notes receivable from third parties (included in other receivables and other assets), Carrying Amount	12,823,000
Long-term debt, including current portion, Carrying Amount	741,187,000
Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	225,414,000
Notes receivable from third parties (included in other receivables and other assets), Fair Value Disclosure	10,881,000
Debt Instrument, Fair Value Disclosure	0
Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	0
Notes receivable from third parties (included in other receivables and other assets), Fair Value Disclosure	1,844,000
Debt Instrument, Fair Value Disclosure	746,682,000
Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	0
Notes receivable from third parties (included in other receivables and other assets), Fair Value Disclosure	0
Debt Instrument, Fair Value Disclosure	$ 0
Two Point Five Percentage Convertible Notes [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	2.50%	2.50%
Three Point Zero Percentage Convertible Notes [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	3.00%	3.00%

Stock Repurchases (Details)

Stock Repurchases (Details) $ in Millions	6 Months Ended
	Jun. 30, 2017USD ($)shares
Stock Repurchase Program, Remaining Authorized Repurchase Amount	$ 90.7
Restricted Stock [Member]
Treasury Stock, Shares, Acquired | shares	110,298
Treasury Stock, Value, Acquired, Cost Method	$ 7.6

Noncontrolling Interests in S42

Noncontrolling Interests in Subsidiaries (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Noncontrolling Interests in Subsidiaries [Line Items]
Noncontrolling interests in subsidiaries	$ 134,585		$ 134,585		$ 135,376
Net Income (Loss)	(29,085)	$ (50,933)	(18,429)	$ (71,457)
Net Income (Loss) Attributable to Noncontrolling Interest	3,723	$ 4,226	10,296	10,888
Inland River Services [Member] | Other Inland River Services Noncontrolling Interests [Member]
Noncontrolling Interests in Subsidiaries [Line Items]
Noncontrolling interests in subsidiaries	$ 963		$ 963		980
Shipping Services [Member] | Sea-Vista [Member]
Noncontrolling Interests in Subsidiaries [Line Items]
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners	49.00%		49.00%
Noncontrolling interests in subsidiaries	$ 118,798		$ 118,798		106,054
Assets, Net	$ 242,400		242,400
Net Income (Loss)			26,000	21,700
Net Income (Loss) Attributable to Noncontrolling Interest			$ 12,700	$ 10,600
Discontinued Operations [Member]
Noncontrolling Interests in Subsidiaries [Line Items]
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners	1.80%		1.80%
Noncontrolling interests in subsidiaries	$ 14,673		$ 14,673		28,190
Other Segments [Member] | Other Noncontrolling Interests [Member]
Noncontrolling Interests in Subsidiaries [Line Items]
Noncontrolling interests in subsidiaries	$ 151		$ 151		$ 152
Minimum [Member] | Inland River Services [Member] | Other Inland River Services Noncontrolling Interests [Member]
Noncontrolling Interests in Subsidiaries [Line Items]
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners	3.00%		3.00%
Minimum [Member] | Other Segments [Member] | Other Noncontrolling Interests [Member]
Noncontrolling Interests in Subsidiaries [Line Items]
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners	5.00%		5.00%
Maximum [Member] | Inland River Services [Member] | Other Inland River Services Noncontrolling Interests [Member]
Noncontrolling Interests in Subsidiaries [Line Items]
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners	51.80%		51.80%
Maximum [Member] | Discontinued Operations [Member]
Noncontrolling Interests in Subsidiaries [Line Items]
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners	50.00%		50.00%
Maximum [Member] | Other Segments [Member] | Other Noncontrolling Interests [Member]
Noncontrolling Interests in Subsidiaries [Line Items]
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners	14.60%		14.60%

Multiemployer Pension Plans (De

Multiemployer Pension Plans (Details) $ in Millions	Sep. 30, 2016USD ($)
American Maritime Officers Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and other postretirement benefit plans, withdrawal liability	$ 28.6

Share Based Compensation (Share

Share Based Compensation (Share Based Compensation Plans) (Details)	6 Months Ended
	Jun. 30, 2017shares
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Director stock awards granted	750,000
Employee Stock Purchase Plan shares issued	14,624,000
Restricted stock awards granted	144,750,000
Restricted stock awards forfeited	2,117,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Stock Options, Outstanding as of December 31, 2016	1,639,865,000
Stock Option, Granted	916,258,000
Stock Option, Exercised	(138,648,000)
Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures in Period	3,374,000
Stock Option, Expired	(21,442,000)
Stock Options, Outstanding as of June 30, 2017	2,392,659,000
Shares available for future grants and ESPP purchases as of June 30, 2017	504,570,000
Stock options granted under make-whole provisions	846,353

Commitments And Contingencies (

Commitments And Contingencies (Narrative) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2013claim	Dec. 31, 2012claim	Dec. 31, 2010claim	Jun. 30, 2017USD ($)equipment
Loss Contingencies [Line Items]
Unrecorded Unconditional Purchase Obligation, Due in Remainder of Fiscal Year					$ 20,136
Unrecorded Unconditional Purchase Obligation, Due in Second Years					3,185
Unrecorded Unconditional Purchase Obligation, Due in Third Year					463
Unrecorded Unconditional Purchase Obligation					$ 23,784
Multi-district Litigation [Member]
Loss Contingencies [Line Items]
Claims Filed | claim				1
Loss Contingency, Number of Plaintiffs	11
Abney Litigation [Member]
Loss Contingencies [Line Items]
Claims Filed | claim			668
Abood Litigation [Member]
Loss Contingencies [Line Items]
Claims Filed | claim		174
U.S. Flag Articulated Tug-Barge [Member]
Loss Contingencies [Line Items]
Unrecorded Unconditional Purchase Obligation, Maximum Quantity | equipment					1
U.S.-flag Harbor Tugs [Member]
Loss Contingencies [Line Items]
Unrecorded Unconditional Purchase Obligation, Maximum Quantity | equipment					2
Inland River Towboats [Member]
Loss Contingencies [Line Items]
Unrecorded Unconditional Purchase Obligation, Maximum Quantity | equipment					2
Shipping Services [Member]
Loss Contingencies [Line Items]
Unrecorded Unconditional Purchase Obligation, Due in Remainder of Fiscal Year					$ 8,356
Unrecorded Unconditional Purchase Obligation, Due in Second Years					2,259
Unrecorded Unconditional Purchase Obligation, Due in Third Year					0
Unrecorded Unconditional Purchase Obligation					10,615
Inland River Services [Member]
Loss Contingencies [Line Items]
Unrecorded Unconditional Purchase Obligation, Due in Remainder of Fiscal Year					11,780
Unrecorded Unconditional Purchase Obligation, Due in Second Years					926
Unrecorded Unconditional Purchase Obligation, Due in Third Year					463
Unrecorded Unconditional Purchase Obligation					$ 13,169

Segment Information (Operating

Segment Information (Operating Results, Capital Expenditures And Assets By Reportable Segments) (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Segment Reporting Information [Line Items]
Operating Revenues	$ 115,791,000	$ 99,647,000	$ 234,205,000	$ 204,699,000
Costs and Expenses [Abstract]
Administrative and general	25,540,000	21,361,000	48,418,000	44,037,000
Depreciation and amortization	17,469,000	15,043,000	34,188,000	30,141,000
Total costs and expenses	112,695,000	100,431,000	227,504,000	201,241,000
Gains (Losses) on Asset Dispositions and Impairments, Net	5,897,000	2,586,000	5,709,000	3,183,000
Operating Income (Loss)	8,993,000	1,802,000	12,410,000	6,641,000
Other Income and Expenses [Abstract]
Derivative gains (losses), net	16,897,000	(2,574,000)	19,727,000	(2,665,000)
Foreign currency gains (losses), net	(1,470,000)	797,000	(71,000)	2,394,000
Other, net	424,000	(7,652,000)	4,000	(7,649,000)
Equity in Earnings (Losses) of 50% or Less Owned Companies, Net of Tax	2,333,000	(3,847,000)	2,441,000	(6,057,000)
Loss Before Taxes and Equity Earnings	(6,453,000)	(33,550,000)	13,439,000	(50,740,000)
Capital Expenditures			80,987,000	155,990,000
Property, Plant and Equipment, Gross	1,340,400,000		1,340,400,000		$ 1,178,556,000
Accumulated depreciation	467,925,000		467,925,000		444,559,000
Construction in progress	133,537,000		133,537,000		246,010,000
Net property and equipment	1,006,012,000		1,006,012,000		980,007,000
Inventories	2,444,000		2,444,000		2,582,000
Goodwill	32,749,000		32,749,000		32,758,000
Intangible Assets, Net	18,931,000		18,931,000		20,078,000
Disposal Group, Including Discontinued Operation, Assets	55,700,000	1,200,824,000	55,700,000	1,200,824,000
Total assets	1,773,885,000	3,001,317,000	1,773,885,000	3,001,317,000	$ 2,862,321,000
Inland River Services [Member]
Segment Reporting Information [Line Items]
Operating Revenues	37,644,000	33,814,000	80,313,000	73,428,000
Shipping Services [Member]
Segment Reporting Information [Line Items]
Operating Revenues	72,023,000	55,620,000	139,662,000	112,675,000
Witt O'Brien's LLC [Member]
Segment Reporting Information [Line Items]
Operating Revenues	6,008,000	10,098,000	13,998,000	18,346,000
Other Segments [Member]
Segment Reporting Information [Line Items]
Operating Revenues	116,000	115,000	232,000	250,000
Corporate And Eliminations [Member]
Segment Reporting Information [Line Items]
Operating Revenues	0	0	0	0
Operating Segments [Member]
Segment Reporting Information [Line Items]
Operating Revenues	115,791,000	99,647,000	234,205,000	204,699,000
Costs and Expenses [Abstract]
Operating Expenses	69,686,000	64,027,000	144,898,000	127,063,000
Administrative and general	25,540,000	21,361,000	48,418,000	44,037,000
Depreciation and amortization	17,469,000	15,043,000	34,188,000	30,141,000
Total costs and expenses	112,695,000	100,431,000	227,504,000	201,241,000
Gains (Losses) on Asset Dispositions and Impairments, Net	5,897,000	2,586,000	5,709,000	3,183,000
Operating Income (Loss)	8,993,000	1,802,000	12,410,000	6,641,000
Other Income and Expenses [Abstract]
Derivative gains (losses), net	16,897,000	(2,574,000)	19,727,000	(2,665,000)
Foreign currency gains (losses), net	(1,470,000)	797,000	(71,000)	2,394,000
Other, net	424,000	(7,652,000)	4,000	(7,649,000)
Equity in Earnings (Losses) of 50% or Less Owned Companies, Net of Tax	2,333,000	(3,847,000)	2,441,000	(6,057,000)
Capital Expenditures			80,987,000	155,990,000
Property, Plant and Equipment, Gross	1,340,400,000	1,008,437,000	1,340,400,000	1,008,437,000
Accumulated depreciation	467,925,000	418,798,000	467,925,000	418,798,000
Property, Plant and Equipment, Net In Service	872,475,000	589,639,000	872,475,000	589,639,000
Construction in progress	133,537,000	296,721,000	133,537,000	296,721,000
Net property and equipment	1,006,012,000	886,360,000	1,006,012,000	886,360,000
Investments, at Equity, and Advances to 50% or Less Owned Companies	174,106,000	195,352,000	174,106,000	195,352,000
Inventories	2,444,000	2,722,000	2,444,000	2,722,000
Goodwill	32,749,000	52,394,000	32,749,000	52,394,000
Intangible Assets, Net	18,931,000	24,116,000	18,931,000	24,116,000
Other Current And Long-Term Assets, Excluding Cash And Near Cash Assets	118,029,000	99,652,000	118,029,000	99,652,000
Operating Segments [Member] | Inland River Services [Member]
Segment Reporting Information [Line Items]
Operating Revenues	37,644,000	33,814,000	80,313,000	73,428,000
Costs and Expenses [Abstract]
Operating Expenses	31,902,000	27,446,000	64,471,000	57,564,000
Administrative and general	4,725,000	3,777,000	8,517,000	7,689,000
Depreciation and amortization	6,483,000	6,254,000	13,075,000	13,391,000
Total costs and expenses	43,110,000	37,477,000	86,063,000	78,644,000
Gains (Losses) on Asset Dispositions and Impairments, Net	5,891,000	2,580,000	6,124,000	3,185,000
Operating Income (Loss)	425,000	(1,083,000)	374,000	(2,031,000)
Other Income and Expenses [Abstract]
Derivative gains (losses), net	0	0	0	0
Foreign currency gains (losses), net	(1,630,000)	1,018,000	(262,000)	2,455,000
Other, net	0	(4,000)	0	(4,000)
Equity in Earnings (Losses) of 50% or Less Owned Companies, Net of Tax	(1,264,000)	(1,677,000)	(3,642,000)	(4,455,000)
Segment Profit (Loss)	(2,469,000)	(1,746,000)	(3,530,000)	(4,035,000)
Capital Expenditures			22,754,000	7,705,000
Property, Plant and Equipment, Gross	421,117,000	386,216,000	421,117,000	386,216,000
Accumulated depreciation	170,162,000	154,893,000	170,162,000	154,893,000
Property, Plant and Equipment, Net In Service	250,955,000	231,323,000	250,955,000	231,323,000
Construction in progress	17,598,000	7,663,000	17,598,000	7,663,000
Net property and equipment	268,553,000	238,986,000	268,553,000	238,986,000
Investments, at Equity, and Advances to 50% or Less Owned Companies	66,956,000	79,154,000	66,956,000	79,154,000
Inventories	1,517,000	1,824,000	1,517,000	1,824,000
Goodwill	2,391,000	2,418,000	2,391,000	2,418,000
Intangible Assets, Net	11,238,000	5,521,000	11,238,000	5,521,000
Other Current And Long-Term Assets, Excluding Cash And Near Cash Assets	42,253,000	45,428,000	42,253,000	45,428,000
Total assets	392,908,000	373,331,000	392,908,000	373,331,000
Operating Segments [Member] | Shipping Services [Member]
Segment Reporting Information [Line Items]
Operating Revenues	72,023,000	55,620,000	139,662,000	112,675,000
Costs and Expenses [Abstract]
Operating Expenses	33,850,000	30,269,000	71,204,000	57,503,000
Administrative and general	8,028,000	7,337,000	15,116,000	14,255,000
Depreciation and amortization	10,115,000	7,415,000	19,276,000	13,977,000
Total costs and expenses	51,993,000	45,021,000	105,596,000	85,735,000
Gains (Losses) on Asset Dispositions and Impairments, Net	6,000	6,000	(415,000)	0
Operating Income (Loss)	20,036,000	10,605,000	33,651,000	26,940,000
Other Income and Expenses [Abstract]
Derivative gains (losses), net	0	0	0	0
Foreign currency gains (losses), net	8,000	(6,000)	3,000	(9,000)
Other, net	421,000	(928,000)	59,000	(927,000)
Equity in Earnings (Losses) of 50% or Less Owned Companies, Net of Tax	5,621,000	(1,591,000)	6,657,000	(1,565,000)
Segment Profit (Loss)	26,086,000	8,080,000	40,370,000	24,439,000
Capital Expenditures			58,018,000	148,410,000
Property, Plant and Equipment, Gross	888,563,000	588,649,000	888,563,000	588,649,000
Accumulated depreciation	277,257,000	244,910,000	277,257,000	244,910,000
Property, Plant and Equipment, Net In Service	611,306,000	343,739,000	611,306,000	343,739,000
Construction in progress	115,939,000	290,582,000	115,939,000	290,582,000
Net property and equipment	727,245,000	634,321,000	727,245,000	634,321,000
Investments, at Equity, and Advances to 50% or Less Owned Companies	48,486,000	56,385,000	48,486,000	56,385,000
Inventories	744,000	799,000	744,000	799,000
Goodwill	1,852,000	1,852,000	1,852,000	1,852,000
Intangible Assets, Net	0	0	0	0
Other Current And Long-Term Assets, Excluding Cash And Near Cash Assets	24,367,000	27,477,000	24,367,000	27,477,000
Total assets	802,694,000	720,834,000	802,694,000	720,834,000
Operating Segments [Member] | Witt O'Brien's LLC [Member]
Segment Reporting Information [Line Items]
Operating Revenues	6,061,000	10,146,000	14,069,000	18,430,000
Costs and Expenses [Abstract]
Operating Expenses	4,043,000	6,427,000	9,415,000	12,232,000
Administrative and general	2,462,000	3,475,000	5,681,000	7,448,000
Depreciation and amortization	205,000	448,000	407,000	903,000
Total costs and expenses	6,710,000	10,350,000	15,503,000	20,583,000
Gains (Losses) on Asset Dispositions and Impairments, Net	0	0	0	(2,000)
Operating Income (Loss)	(649,000)	(204,000)	(1,434,000)	(2,155,000)
Other Income and Expenses [Abstract]
Derivative gains (losses), net	0	0	0	0
Foreign currency gains (losses), net	23,000	(74,000)	33,000	(100,000)
Other, net	0	0	0	0
Equity in Earnings (Losses) of 50% or Less Owned Companies, Net of Tax	(20,000)	100,000	137,000	186,000
Segment Profit (Loss)	(646,000)	(178,000)	(1,264,000)	(2,069,000)
Capital Expenditures			60,000	0
Property, Plant and Equipment, Gross	1,227,000	2,861,000	1,227,000	2,861,000
Accumulated depreciation	892,000	2,476,000	892,000	2,476,000
Property, Plant and Equipment, Net In Service	335,000	385,000	335,000	385,000
Construction in progress	0	0	0	0
Net property and equipment	335,000	385,000	335,000	385,000
Investments, at Equity, and Advances to 50% or Less Owned Companies	663,000	611,000	663,000	611,000
Inventories	183,000	99,000	183,000	99,000
Goodwill	28,506,000	48,124,000	28,506,000	48,124,000
Intangible Assets, Net	7,693,000	18,595,000	7,693,000	18,595,000
Other Current And Long-Term Assets, Excluding Cash And Near Cash Assets	13,190,000	14,983,000	13,190,000	14,983,000
Total assets	50,570,000	82,797,000	50,570,000	82,797,000
Operating Segments [Member] | Other Segments [Member]
Segment Reporting Information [Line Items]
Operating Revenues	116,000	115,000	232,000	250,000
Costs and Expenses [Abstract]
Operating Expenses	0	0	0	0
Administrative and general	225,000	174,000	379,000	424,000
Depreciation and amortization	0	0	0	0
Total costs and expenses	225,000	174,000	379,000	424,000
Gains (Losses) on Asset Dispositions and Impairments, Net	0	0	0	0
Operating Income (Loss)	(109,000)	(59,000)	(147,000)	(174,000)
Other Income and Expenses [Abstract]
Derivative gains (losses), net	0	0	0	0
Foreign currency gains (losses), net	0	1,000	0	0
Other, net	0	(6,723,000)	(300,000)	(6,723,000)
Equity in Earnings (Losses) of 50% or Less Owned Companies, Net of Tax	(2,004,000)	(679,000)	(711,000)	(223,000)
Segment Profit (Loss)	(2,113,000)	(7,460,000)	(1,158,000)	(7,120,000)
Capital Expenditures			0	0
Property, Plant and Equipment, Gross	0	0	0	0
Accumulated depreciation	0	0	0	0
Property, Plant and Equipment, Net In Service	0	0	0	0
Construction in progress	0	0	0	0
Net property and equipment	0	0	0	0
Investments, at Equity, and Advances to 50% or Less Owned Companies	58,001,000	59,202,000	58,001,000	59,202,000
Inventories	0	0	0	0
Goodwill	0	0	0	0
Intangible Assets, Net	0	0	0	0
Other Current And Long-Term Assets, Excluding Cash And Near Cash Assets	11,427,000	7,961,000	11,427,000	7,961,000
Total assets	69,428,000	67,163,000	69,428,000	67,163,000
Operating Segments [Member] | Corporate And Eliminations [Member]
Segment Reporting Information [Line Items]
Operating Revenues	(53,000)	(48,000)	(71,000)	(84,000)
Costs and Expenses [Abstract]
Operating Expenses	(109,000)	(115,000)	(192,000)	(236,000)
Administrative and general	10,100,000	6,598,000	18,725,000	14,221,000
Depreciation and amortization	666,000	926,000	1,430,000	1,870,000
Total costs and expenses	10,657,000	7,409,000	19,963,000	15,855,000
Gains (Losses) on Asset Dispositions and Impairments, Net	0	0	0	0
Operating Income (Loss)	(10,710,000)	(7,457,000)	(20,034,000)	(15,939,000)
Other Income and Expenses [Abstract]
Derivative gains (losses), net	16,897,000	(2,574,000)	19,727,000	(2,665,000)
Foreign currency gains (losses), net	129,000	(142,000)	155,000	48,000
Other, net	3,000	3,000	245,000	5,000
Equity in Earnings (Losses) of 50% or Less Owned Companies, Net of Tax	0	0	0	0
Capital Expenditures			155,000	(125,000)
Property, Plant and Equipment, Gross	29,493,000	30,711,000	29,493,000	30,711,000
Accumulated depreciation	19,614,000	16,519,000	19,614,000	16,519,000
Property, Plant and Equipment, Net In Service	9,879,000	14,192,000	9,879,000	14,192,000
Construction in progress	0	(1,524,000)	0	(1,524,000)
Net property and equipment	9,879,000	12,668,000	9,879,000	12,668,000
Investments, at Equity, and Advances to 50% or Less Owned Companies	0	0	0	0
Inventories	0	0	0	0
Goodwill	0	0	0	0
Intangible Assets, Net	0	0	0	0
Other Current And Long-Term Assets, Excluding Cash And Near Cash Assets	26,792,000	3,803,000	26,792,000	3,803,000
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Operating Revenues	0	0	0	0
Intersegment Eliminations [Member] | Inland River Services [Member]
Segment Reporting Information [Line Items]
Operating Revenues	0	0	0	0
Intersegment Eliminations [Member] | Shipping Services [Member]
Segment Reporting Information [Line Items]
Operating Revenues	0	0	0	0
Intersegment Eliminations [Member] | Witt O'Brien's LLC [Member]
Segment Reporting Information [Line Items]
Operating Revenues	(53,000)	(48,000)	(71,000)	84,000
Intersegment Eliminations [Member] | Other Segments [Member]
Segment Reporting Information [Line Items]
Operating Revenues	0	0	0	0
Intersegment Eliminations [Member] | Corporate And Eliminations [Member]
Segment Reporting Information [Line Items]
Operating Revenues	53,000	48,000	71,000	(84,000)
Segment Reconciling Items [Member]
Other Income and Expenses [Abstract]
Other Income (Expense) not included in Segment Profit (Loss)	31,297,000	25,923,000	18,631,000	49,461,000
Less Equity Earnings included in Segment Profit (Loss)	(2,333,000)	3,847,000	(2,441,000)	6,057,000
Cash And Near Cash Assets	$ 365,914,000	$ 539,897,000	$ 365,914,000	$ 539,897,000

Discontinued Operations (Detail

Discontinued Operations (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Costs and Expenses [Abstract]
Total costs and expenses	$ 112,695	$ 100,431	$ 227,504	$ 201,241
Gains (Losses) on Asset Dispositions and Impairments, Net	5,897	2,586	5,709	3,183
Net Income (Loss)	(28,629)	(27,169)	(34,077)	(37,417)
Offshore Marine Services [Member]
Operating Revenues	27,987	57,271	62,291	117,150
Costs and Expenses [Abstract]
Operating	32,509	44,245	65,888	93,095
Administrative and general	17,856	11,929	29,682	24,327
Depreciation and amortization	9,678	15,254	22,181	30,092
Total costs and expenses	60,043	71,428	117,751	147,514
Operating Income (Loss)	(32,656)	(34,514)	(51,241)	(51,101)
Other Income (Expense), Net	(5,346)	(6,702)	1,780	(11,682)
Income Tax Expense (Benefit)	(9,509)	(13,742)	(12,931)	(20,568)
Equity in Earnings (Losses) of 50% or Less Owned Companies	1,225	(3,315)	1,663	(1,154)
Net Income (Loss)	(27,268)	(30,789)	(34,867)	(43,369)
Net Income (Loss) Attributable to Noncontrolling Interests	(1,688)	(209)	(1,892)	(831)
Illinois Corn Processing LLC [Member]
Operating Revenues	39,676	40,576	78,061	90,185
Costs and Expenses [Abstract]
Operating	40,205	36,153	76,306	82,442
Administrative and general	1,363	912	2,109	1,568
Depreciation and amortization	1,179	1,064	2,354	2,117
Total costs and expenses	42,747	38,129	80,769	86,127
Operating Income (Loss)	(3,071)	2,447	(2,708)	4,058
Other Income (Expense), Net	487	1,791	2,335	2,477
Income Tax Expense (Benefit)	(668)	1,267	67	1,982
Net Income (Loss)	(1,916)	2,971	(440)	4,553
Net Income (Loss) Attributable to Noncontrolling Interests	(915)	984	(539)	1,406
Intersegment Eliminations [Member]
Operating Revenues	(520)	(456)	(1,176)	(1,068)
Costs and Expenses [Abstract]
Operating	(561)	(543)	(1,289)	(1,250)
Administrative and general	(19)	(27)	(42)	(53)
Total costs and expenses	(580)	(570)	(1,331)	(1,303)
Operating Income (Loss)	60	114	155	235
Other Income (Expense), Net	795	884	1,738	1,917
Income Tax Expense (Benefit)	300	349	663	753
Net Income (Loss)	555	649	1,230	1,399
Offshore Marine Services [Member] | Offshore Marine Services [Member]
Costs and Expenses [Abstract]
Gains (Losses) on Asset Dispositions and Impairments, Net	$ (600)	$ (20,357)	$ 4,219	$ (20,737)