Seacor (CKH) 10-Q 2 Nov 17 2017 Q3 Quarterly report Financial data

Document And Entity Information

Document And Entity Information - shares	9 Months Ended
	Sep. 30, 2017	Oct. 27, 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	Sep. 30, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	Q3
Amendment Flag	false
Entity Common Stock, Shares Outstanding		17,859,335
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	Sep. 30, 2017	Dec. 31, 2016
Current Assets:
Cash and cash equivalents	$ 267,156	$ 256,638
Restricted cash	2,436	2,249
Marketable securities	62,606	76,137
Receivables:
Trade, net of allowance for doubtful accounts of $2,400 and $2,989 in 2017 and 2016, respectively	83,287	108,641
Other Receivables	38,176	35,482
Inventories	3,952	2,582
Prepaid expenses and other	6,741	3,707
Discontinued operations	0	277,365
Total current assets	464,354	762,801
Property and Equipment:
Property, Plant and Equipment, Gross	1,483,434	1,178,556
Accumulated depreciation	487,049	444,559
Property, Plant and Equipment, Other, Net in Service	996,385	733,997
Construction in progress	22,769	246,010
Net property and equipment	1,019,154	980,007
Investments, at Equity, and Advances to 50% or Less Owned Companies	175,387	175,461
Construction Reserve Funds	51,846	75,753
Goodwill	32,773	32,758
Intangible Assets, Net	30,655	20,078
Other Assets	8,796	17,189
Discontinued Operations	0	798,274
Total assets	1,782,965	2,862,321
Current Liabilities:
Current portion of long-term debt	119,840	163,202
Accounts payable and accrued expenses	31,518	59,563
Other current liabilities	70,762	62,164
Discontinued operations	0	85,020
Total current liabilities	222,120	369,949
Long-Term Debt	619,712	631,084
Exchange Option Liability on Subsidiary Convertible Senior Notes	0	19,436
Deferred Income Taxes	165,093	157,441
Deferred Gains and Other Liabilities	81,238	98,098
Discontinued Operations	0	390,045
Total liabilities	1,088,163	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; 38,473,585 and 37,939,032 shares issued in 2017 and 2016, respectively	385	379
Additional paid-in capital	1,557,086	1,518,635
Retained earnings	377,700	910,723
Shares held in treasury of 20,614,250 and 20,538,327 in 2017 and 2016, respectively, at cost	1,363,558	1,357,331
Accumulated other comprehensive loss, net of tax	(266)	(11,514)
Stockholders' equity attributable to parent, total	571,347	1,060,892
Noncontrolling interests in subsidiaries	123,455	135,376
Total equity	694,802	1,196,268
Liabilities and stockholders' equity, total	$ 1,782,965	$ 2,862,321

Condensed Consolidated Balance3

Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Trade receivables, allowance for doubtful accounts	$ 2,400	$ 2,989
Common Stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	60,000,000	60,000,000
Common stock, shares issued	38,473,585	37,939,032
Treasury stock, shares held in treasury	20,614,250	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		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Income Statement [Abstract]
Operating Revenues	$ 158,171,000	$ 109,570,000	$ 392,376,000	$ 314,269,000
Costs and Expenses [Abstract]
Operating	107,258,000	66,573,000	252,156,000	193,636,000
Administrative and general	20,531,000	20,931,000	68,949,000	64,968,000
Depreciation and amortization	20,501,000	15,864,000	54,689,000	46,005,000
Total costs and expenses	148,290,000	103,368,000	375,794,000	304,609,000
Gains (Losses) on Asset Dispositions and Impairments, Net	5,209,000	(593,000)	10,918,000	2,590,000
Operating Income	15,090,000	5,609,000	27,500,000	12,250,000
Other Income (Expense):
Interest income	2,367,000	4,492,000	6,651,000	13,100,000
Interest expense	9,121,000	9,955,000	31,101,000	29,892,000
Debt extinguishment gains (losses), net	3,000	557,000	(94,000)	5,395,000
Marketable security losses, net	(12,478,000)	(9,484,000)	(13,316,000)	(52,454,000)
Derivative gains (losses), net	0	(862,000)	19,727,000	(3,527,000)
Foreign currency gains, net	969,000	418,000	898,000	2,812,000
Other, net	64,000	(5,461,000)	68,000	(13,110,000)
Total Other Nonoperating Income (Expense)	(18,196,000)	(20,295,000)	(17,167,000)	(77,676,000)
Income (Loss) from Continuing Operations Before Income Tax Benefit and Equity in Earnings (Losses) of 50% or Less Owned Companies	(3,106,000)	(14,686,000)	10,333,000	(65,426,000)
Income Tax Benefit	(12,795,000)	(7,164,000)	(12,563,000)	(29,921,000)
Income (Loss) from Continuing Operations Before Equity in Earnings (Losses) of 50% or Less Owned Companies	9,689,000	(7,522,000)	22,896,000	(35,505,000)
Equity in Earnings (Losses) of 50% or Less Owned Companies, Net of Tax	488,000	(1,112,000)	2,929,000	(7,169,000)
Income (Loss) from Continuing Operations	10,177,000	(8,634,000)	25,825,000	(42,674,000)
Income (Loss) from Discontinued Operations, Net of Tax	10,927,000	(25,392,000)	(23,150,000)	(62,809,000)
Net Income (Loss)	21,104,000	(34,026,000)	2,675,000	(105,483,000)
Net Income Attributable to Noncontrolling Interests in Subsidiaries	3,543,000	5,777,000	13,839,000	16,665,000
Net Income (Loss) attributable to SEACOR Holdings Inc.	$ 17,561,000	$ (39,803,000)	$ (11,164,000)	$ (122,148,000)
Basic Earnings (Loss) Per Common Share of SEACOR Holdings Inc.:
Continuing operations	$ 0.38	$ (0.82)	$ 0.55	$ (3.45)
Discontinued operations	0.62	(1.53)	(1.20)	(3.78)
Basic Earnings (Loss) Per Common Share of SEACOR Holdings Inc.	1	(2.35)	(0.65)	(7.23)
Diluted Earnings (Loss) Per Common Share of SEACOR Holdings Inc.:
Continuing operations	0.38	(0.82)	0.55	(3.45)
Discontinued operations	0.62	(1.53)	(1.19)	(3.78)
Diluted Earnings (Loss) Per Common Share of SEACOR Holdings Inc.	$ 1	$ (2.35)	$ (0.64)	$ (7.23)
Weighted Average Common Shares Outstanding:
Basic	17,508,770	16,943,647	17,265,140	16,896,751
Diluted	17,637,824	16,943,647	17,510,560	16,896,751

Condensed Consolidated Stateme5

Condensed Consolidated Statements of Comprehensive Income (Loss) Statement - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Net Income (Loss)	$ 21,104	$ (34,026)	$ 2,675	$ (105,483)
Foreign currency translation gains (losses)	425	(305)	2,147	(6,641)
Reclassification of foreign currency translation losses to foreign currency gains, net	0	(74)	0	(74)
Derivative losses on cash flow hedges	0	(187)	(389)	(3,855)
Other	(5)	7	11	16
Other Comprehensive Income (Loss), before Tax	430	369	1,889	(8,318)
Income tax benefit (expense)	(151)	(182)	(605)	2,612
Other Comprehensive Income, Net of Tax	279	187	1,284	(5,706)
Comprehensive Income (Loss)	21,383	(33,839)	3,959	(111,189)
Comprehensive Income attributable to Noncontrolling Interests in Subsidiaries	3,543	5,625	14,000	15,810
Comprehensive Income (Loss) attributable to SEACOR Holdings Inc.	17,840	(39,464)	(10,041)	(126,999)
Interest Expense [Member]
Reclassification of derivative losses on cash flow hedges to equity in earnings (losses) of 50% or less owned companies	0	9	33	9
Equity Method Investments [Member]
Reclassification of derivative losses on cash flow hedges to equity in earnings (losses) of 50% or less owned companies	$ 0	$ (785)	$ (109)	$ (2,111)

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	1,443	0	0	0	1,443	0	0
Exercise of stock options	14,984	4	14,980	0	0	0	0
Director stock awards	63	0	63	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	(927)	0	927	0	0	0	0
Purchases of treasury shares	(7,569)	0	0	0	(7,569)	0	0
Amortization of share awards	22,691	0	22,691	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
Disposition of subsidiary with noncontrolling interests	(14,673)	0	0	0	0	0	(14,673)
Distributions to noncontrolling interests	7,430	0	0	0	0	0	7,430
Comprehensive income:
Net loss attributable to SEACOR Holdings Inc.	(11,164)	0	0		0	0
Net Income Attributable to Noncontrolling Interests in Subsidiaries	13,839
Net Income	2,675
Other comprehensive income	1,284	0	0	0	0	1,123	161
Total equity	$ 694,802	$ 385	$ 1,557,086	$ 377,700	$ (1,363,558)	$ (266)	$ 123,455

Condensed Consolidated Stateme7

Condensed Consolidated Statements Of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Statement of Cash Flows [Abstract]
Net Cash Provided by Operating Activities of Continuing Operations	$ 85,088	$ 60,547
Cash Flows from Investing Activities
Purchases of property and equipment	99,306	207,825
Proceeds from disposition of property and equipment	27,614	142,076
Investments in and advances to 50% or less owned companies	7,636	4,464
Return of investments and advances from 50% or less owned companies	9,676	8,361
Proceeds on the sale of a controlling interest in a subsidiary	5,000	0
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	24,349	(1,824)
Net increase in restricted cash	187	2,244
Decrease in construction reserve funds	37,714	16,827
Increase in construction reserve funds	13,807	0
Business acquisitions, net of cash acquired	(5,250)	0
Net cash used in investing activities of continuing operations	(11,333)	(50,192)
Cash Flows from Financing Activities
Payments on long-term debt and capital lease obligations	133,151	131,196
Proceeds from issuance of long term debt, net of issue costs	38,900	78,380
Purchase of conversion option in convertible debt	1,354	7,096
Common stock acquired for treasury	7,569	2,396
Proceeds and tax benefits from share award plans	16,427	1,618
Distributions to noncontrolling interests	0	(200)
Net cash used in financing activities of continuing operations	(86,747)	(60,890)
Effect of Exchange Rate Changes on Cash and Cash Equivalents	856	(1,937)
Net Decrease in Cash and Cash Equivalents from Continuing Operations	(12,136)	(52,472)
Cash Flows from Discontinued Operations:
Operating Activities	26,875	17,338
Investing Activities	2,720	(14,304)
Financing Activities	(7,149)	7,753
Effects of Exchange Rate Changes on Cash and Cash Equivalents	208	499
Net Increase in Cash and Cash Equivalents from Discontinued Operations	22,654	11,286
Net Increase (Decrease) in Cash and Cash Equivalents	10,518	(41,186)
Cash and Cash Equivalents, Beginning of Period	256,638	357,146
Cash and Cash Equivalents, End of Period	$ 267,156	$ 315,960

Basis of Presentation and Accou

Basis of Presentation and Accounting Policy	9 Months Ended
	Sep. 30, 2017
Accounting Policies [Abstract]
Basis of Presentation and Accounting Policy	he condensed consolidated financial information for the three and nine months ended September 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 September 30, 2017 , its results of operations for the three and nine months ended September 30, 2017 and 2016 , its comprehensive income (loss) for the three and nine months ended September 30, 2017 and 2016 , its changes in equity for the nine months ended September 30, 2017 , and its cash flows for the nine months ended September 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 15). On July 3, 2017, the Company completed 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 a note from the buyer for $32.8 million after working capital adjustments resulting in a third quarter gain of $10.9 million , net of tax. On September 15, 2017, the Company received payment of the outstanding balance of the note, including accrued and unpaid interest. 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 15). 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 September 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 Articulated tug-barge - U.S.-flag 25 Dry-bulk carrier - 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 nine months ended September 30, 2017 , capitalized interest totaled $2.4 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 nine months ended September 30, 2017 and 2016 , the Company recognized impairment charges of $0.4 million and $1.1 million , respectively, 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 nine months ended September 30, 2017 , the Company recognized an impairment charge of $0.9 million , net of tax, related to its 50% or less owned companies. During the nine months ended September 30, 2016 , the Company did not recognize any impairment charges related to its 50% or less owned companies. Income Taxes. During the nine months ended September 30, 2017 , the Company’s effective income tax rate of (121.6)% was primarily due to the reversal of a provision related to potential tax exposures surrounding the spin-off of Era Group Inc. (“Era Group”) by means of a dividend to SEACOR’s shareholders of all the issued and outstanding common stock of Era Group (the “Era Spin-off”) and taxes not provided on income attributable to noncontrolling interests (see Note 6). 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 nine months ended September 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 (11,126 ) (11,219 ) Amortization of deferred gains included in gains (losses) on asset dispositions and impairments, net (1,764 ) (1,816 ) Other — (1,697 ) Balance at end of period $ 77,253 $ 86,881 Accumulated Other Comprehensive Income (Loss). The components of accumulated other comprehensive income (loss) were as follows (in thousands): SEACOR Holdings Inc. Stockholders’ Equity Noncontrolling Interests Foreign Currency Translation Adjustments Derivative Gains 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) 1,994 (260 ) (6 ) 1,728 153 13 (5 ) $ 1,889 Income tax (expense) benefit (698 ) 91 2 (605 ) — — — (605 ) Nine Months Ended September 30, 2017 $ (266 ) $ — $ — $ (266 ) $ (1,460 ) $ (4 ) $ (2 ) $ 1,284 Earnings (Loss) Per Share. Basic earnings (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 earnings (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 earnings (loss) per common share of SEACOR were as follows (in thousands, except share data): Three Months Ended September 30, Nine Months Ended September 30, Net Income (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 $ 17,561 17,508,770 $ 1.00 $ (11,164 ) 17,265,140 $ (0.65 ) Effect of Dilutive Share Awards: Options and Restricted Stock (1) — 129,054 — 245,420 Convertible Notes (2) — — — — Diluted Weighted Average Common Shares Outstanding $ 17,561 17,637,824 $ 1.00 $ (11,164 ) 17,510,560 $ (0.64 ) 2016 Basic Weighted Average Common Shares Outstanding $ (39,803 ) 16,943,647 $ (2.35 ) $ (122,148 ) 16,896,751 $ (7.23 ) Effect of Dilutive Share Awards: Options and Restricted Stock (3) — — — — Convertible Notes (4) — — — — Diluted Weighted Average Common Shares Outstanding $ (39,803 ) 16,943,647 $ (2.35 ) $ (122,148 ) 16,896,751 $ (7.23 ) ______________________ (1) For the three and nine months ended September 30, 2017 , diluted earnings (loss) per common share of SEACOR excluded 1,727,132 and 2,638,753 , 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 nine months ended September 30, 2017 , diluted earnings (loss) per common share of SEACOR excluded 1,889,027 and 2,488,460 , 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 nine months ended September 30, 2016 , diluted loss per common share of SEACOR excluded 2,041,652 and 2,041,652 , respectively, of certain share awards as the effect of their inclusion in the computation would be anti-dilutive. (4) For the three and nine months ended September 30, 2016 , diluted loss per common share of SEACOR excluded 2,382,626 and 2,910,688 , 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 barge pooling arrangements may result in a gross presentation of operating revenues and expenses for pooled third party equipment resulting in a material increase in operating revenues and expenses, however operating income would remain unchanged. On February 25, 2016, the FASB issued a comprehensive new leasing standard, which is meant to improve 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 unit’s 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.

Business Acquisitions (Notes)

Business Acquisitions (Notes)	9 Months Ended
	Sep. 30, 2017
Business Combinations [Abstract]
Mergers, Acquisitions and Dispositions Disclosures [Text Block]	ISH. On July 3, 2017, International Shipholding Corporation (“ISH”) emerged from bankruptcy pursuant to its chapter 11 plan of reorganization (the “Plan”) 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 SEACOR, acquired all of the equity of the reorganized ISH. 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 assumed $28.7 million of debt primarily from 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 5). ISH, through its subsidiaries, operates a diversified fleet of U.S. and foreign-flag vessels including Pure Car/Truck Carriers (“PCTCs”) and U.S.-flag dry-cargo bulk carriers that provide worldwide and domestic maritime transportation services to commercial and governmental customers. In addition, ISH has investments in two 50% or less owned companies that operate two foreign-flag rail ferries and a railcar repair and maintenance facility. The Company has excluded pro forma financial information with respect to the ISH acquisition as financial information for the specific assets acquired under the Plan were not material or reasonably attainable. The Company performed a preliminary fair value analysis and the purchase price was allocated to the acquired assets and liabilities based on their fair value resulting in no goodwill being recorded. Purchase Price Allocation. The allocation of the purchase price for the Company’s acquisition for the nine months ended September 30, 2017 was as follows (in thousands): Marketable securities $ 13 Trade and other receivables 15,420 Other current assets 2,055 Investments, at Equity, and Advances to 50% or Less Owned Companies 10,000 Property and Equipment 15,478 Intangible Assets 12,658 Other Assets (1) (17,863 ) Accounts payable and other accrued liabilities (18,183 ) Long-Term Debt (including current portion) (28,725 ) Deferred Income Taxes 3,939 Other Liabilities (42 ) Purchase price (2) $ (5,250 ) ______________________ (1) Other Assets is net of debtor-in-possession financing converted into equity of $18.1 million . (2) Purchase price is net of cash acquired totaling $15.7 million .
Schedule of Recognized Identified Assets Acquired and Liabilities Assumed [Table Text Block]	Purchase Price Allocation. The allocation of the purchase price for the Company’s acquisition for the nine months ended September 30, 2017 was as follows (in thousands): Marketable securities $ 13 Trade and other receivables 15,420 Other current assets 2,055 Investments, at Equity, and Advances to 50% or Less Owned Companies 10,000 Property and Equipment 15,478 Intangible Assets 12,658 Other Assets (1) (17,863 ) Accounts payable and other accrued liabilities (18,183 ) Long-Term Debt (including current portion) (28,725 ) Deferred Income Taxes 3,939 Other Liabilities (42 ) Purchase price (2) $ (5,250 ) ______________________ (1) Other Assets is net of debtor-in-possession financing converted into equity of $18.1 million . (2) Purchase price is net of cash acquired totaling $15.7 million

Equipment Acquisitions, Disposi

Equipment Acquisitions, Dispositions and Depreciation and Impairment Policies Equipment Acquisitions, Dispositions and Depreciation and Impairment Policies (Notes)	9 Months Ended
	Sep. 30, 2017
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment Disclosure [Text Block]	During the nine months ended September 30, 2017 , capital expenditures were $99.3 million and primarily related to equipment ordered prior to 2017. Equipment deliveries during the nine months ended September 30, 2017 included two inland river liquid tank barges, three inland river towboats, one U.S.-flag articulated tug-barge, one U.S.-flag product tanker, one U.S.-flag harbor tug and two foreign-flag harbor tugs. During the nine months ended September 30, 2017 , the Company sold 50 dry-cargo barges, two inland river towboats and other property and equipment for net proceeds of $27.6 million and gains of $17.6 million , of which $9.9 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 $1.8 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	9 Months Ended
	Sep. 30, 2017
Equity Method Investment, Summarized Financial Information [Abstract]
Investments, At Equity, And Advances To 50% Or Less Owned Companies	CFCo. 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 nine months ended September 30, 2017 , the Company and its partner each contributed capital of $0.4 million and made working capital advances of $0.5 million to SCFCo, received working capital repayments of $1.7 million from SCFCo and converted $4.2 million of loans to capital. As of September 30, 2017 , the Company had outstanding loans and working capital advances to SCFCo of $27.4 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 nine months ended September 30, 2017 , the Company provided advances of $2.0 million to Trailer Bridge and received repayments of $2.1 million from Trailer Bridge on the secured financing. As of September 30, 2017 , the outstanding amount on the secured financing was $3.9 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 nine months ended September 30, 2017 , the Company received dividends of $12.5 million and capital distributions of $3.5 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 nine months ended September 30, 2017 , the Company and its partner each contributed capital of $0.3 million . RF Vessel Holdings. On July 3, 2017, ISH emerged from bankruptcy pursuant to its chapter 11 plan of reorganization and SEACOR Ocean Transport Inc., a wholly-owned subsidiary of SEACOR, acquired all of the equity of the reorganized ISH (see Note 2). As part of the ISH business acquisition, the Company acquired a 100% interest in Rail-Ferry Vessel Holdings LLC (“RF Vessel Holdings”), which owns two foreign-flag rail ferries. On September 1, 2017, the Company sold a 50% interest in RF Vessel Holdings to G&W Agave Holdings (MI) Inc. for $1.9 million and retained a 50% ownership interest in the newly-formed joint venture. Golfo de Mexico. On July 3, 2017, ISH emerged from bankruptcy pursuant to its chapter 11 plan of reorganization and SEACOR Ocean Transport Inc., a wholly-owned subsidiary of SEACOR, acquired all of the equity of the reorganized ISH (see Note 2). As part of the ISH business acquisition, the Company acquired a 100% interest in Golfo de Mexico Rail-Ferry Holdings LLC (“Golfo de Mexico”), which operates the two foreign-flag rail ferries owned by RF Vessel Holdings. On September 1, 2017, the Company sold a 50% interest in Golfo de Mexico to G&W Agave Holdings (MI) Inc. for $3.1 million and retained a 50% ownership interest in the newly-formed joint venture. 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 nine months ended September 30, 2017 , VA&E borrowed $3.5 million on the credit facility. As of September 30, 2017 , the outstanding balance on the credit facility and subordinated loan was $7.5 million , inclusive of accrued and unpaid interest. During the nine months ended September 30, 2017 , the Company identified indicators of impairment for its investment in VA&E based on their recent financial results and recognized an impairment charge of $0.9 million , net of tax, for an other-than-temporary decline in the fair value of its investment in VA&E (see Note 8). Avion. Avion is a distributor of aircraft and aircraft related parts. During the nine months ended September 30, 2017 , the Company made advances of $1.0 million to Avion and received repayments of $2.0 million from Avion. As of September 30, 2017 , the Company had outstanding advances to Avion of $2.0 million .

Long-Term Debt

Long-Term Debt	9 Months Ended
	Sep. 30, 2017
Long-term Debt and Capital Lease Obligations [Abstract]
Long-Term Debt	5. 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 September 30, 2017 , the Company’s remaining repurchase authority for the Securities was $77.4 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 September 30, 2017 . 2.5% Convertible Senior Notes. During the nine months ended September 30, 2017 , the Company repurchased $61.7 million in principal amount of its 2.5% Convertible Senior Notes for total consideration of $61.9 million . Consideration of $60.5 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 income (loss). Consideration of $1.4 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 September 30, 2017 , the remaining principal amount outstanding of $95.5 million is included in current liabilities as the holders may require the Company to repurchase these notes on December 19, 2017. 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 1,758,107 shares as of September 30, 2017 . 7.375% Senior Notes. During the nine months ended September 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 income (loss). The outstanding principal amount of these notes outstanding was $153.1 million as of September 30, 2017 . SEA-Vista Credit Facility. During the nine months ended September 30, 2017 , SEA-Vista borrowed $38.9 million and repaid $45.9 million on the Revolving Loan and made scheduled repayments of $3.6 million on the Term A-1 Loan and $3.0 million on the Term A-2 Loan. As of September 30, 2017 , SEA-Vista had $21.0 million of remaining borrowing capacity under the Revolving Loan. Subsequent to September 30, 2017 , SEA-Vista borrowed $6.0 million on the Revolving Loan. ISH Credit Facility. On July 3, 2017, ISH emerged from bankruptcy pursuant to the Plan (see Note 2). In conjunction with the emergence under the Plan, ISH assumed debt of $25.0 million under a 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”) (collectively the “ISH Credit Facility”). ISH incurred $0.1 million of issuance costs. The proceeds from this facility will be used for general working capital purposes and payments to ISH’s creditors in accordance with the Plan. During the nine months ended September 30, 2017 , ISH repaid $7.2 million on the ISH Term Loan and $5.0 million on the ISH Revolving Loan. Both loans bear interest at a variable rate of either LIBOR multiplied by the Statutory Reserve Rate or Prime Rate plus an applicable margin, as defined in the ISH Credit Facility. A quarterly fee of 0.5% 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 in the credit agreement. The ISH Credit Facility contains various financial and restrictive covenants including indebtedness to EBITDA and adjusted EBITDA to interest expense maintenance, as defined in the ISH Credit Facility. The ISH Credit Facility is non-recourse to SEACOR and its subsidiaries other than ISH. As of September 30, 2017 , the ISH Credit Facility had $5.0 million of remaining borrowing capacity under the ISH Revolving Loan. Other. During the nine months ended September 30, 2017 the Company acquired $3.9 million of debt related to the ISH acquisition (see Note 2). This debt bears interest at 7.0% and is collateralized by certain acquired assets. During the nine months ended September 30, 2017 , the Company made scheduled payments on other long-term debt of $0.3 million . Letters of Credit. As of September 30, 2017 , the Company had outstanding letters of credit totaling $27.2 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 September 30, 2017 , these guarantees on behalf of SEACOR Marine totaled $84.9 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 nine months ended September 30, 2017 , the Company earned fees of $0.1 million and $0.5 million , respectively. For the three and nine months ended September 30, 2016 , the Company earned fees of $0.1 million and $0.6 million , respectively.

Income Taxes (Notes)

Income Taxes (Notes)	9 Months Ended
	Sep. 30, 2017
Income Tax Disclosure [Abstract]
Income Tax Disclosure [Text Block]	The following table reconciles the difference between the statutory federal income tax rate for the Company and the effective income tax rate on continuing operations for the nine months ended September 30, 2017 : Statutory rate 35.0 % Income subject to tonnage tax (3.4 )% Reversal of uncertain tax position (97.9 )% Non-deductible expenses 1.3 % Noncontrolling interests (55.1 )% Losses of foreign subsidiaries not benefited (13.1 )% State taxes 5.3 % Share award plans 6.3 % (121.6 )% During the year ended December 31, 2013, the Company provided for income taxes of $10.1 million relating to potential tax exposures surrounding the Era Spin-off. During the nine months ended September 30, 2017 , the Company reversed this provision as the statute of limitations expired. In addition, the Company reversed accumulated accrued interest of $2.0 million related to this provision, included as a reduction in interest expense in the accompanying condensed consolidated statements of income (loss).

Derivative Instruments And Hedg

Derivative Instruments And Hedging Strategies	9 Months Ended
	Sep. 30, 2017
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Instruments And Hedging Strategies	ash 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 nine months ended September 30 as follows (in thousands): 2017 2016 Exchange option liability on subsidiary convertible senior notes $ 19,436 $ (3,328 ) Forward currency exchange, option and future contracts 291 (186 ) Exchange traded commodity swap, option and future contracts — (13 ) $ 19,727 $ (3,527 ) 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 September 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 nine months ended September 30 as follows (in thousands): 2017 2016 Exchange option liability on subsidiary convertible senior notes $ 19,436 $ (3,328 ) Forward currency exchange, option and future contracts 291 (186 ) Exchange traded commodity swap, option and future contracts — (13 ) $ 19,727 $ (3,527 )

Stock Repurchases

Stock Repurchases	9 Months Ended
	Sep. 30, 2017
Common Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Stock Repurchases	EACOR’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 September 30, 2017 , the Company’s repurchase authority for the Securities was $77.4 million . During the nine months ended September 30, 2017 , the Company purchased 110,298 shares of Common Stock for treasury from its employees, to cover their tax withholding obligations related to share award transactions, for an aggregate purchase price of $7.6 million . 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)	9 Months Ended
	Sep. 30, 2017
Noncontrolling Interest [Abstract]
Noncontrolling Interests in Subsidiaries Disclosure [Text Block]	oncontrolling interests in the Company’s consolidated subsidiaries were as follows (in thousands): Noncontrolling Interests September 30, 2017 December 31, 2016 Inland River Services: Other 3.0 % – 51.8% $ 959 $ 980 Shipping Services: SEA-Vista 49% 122,344 106,054 Discontinued Operations 1.8 % – 50.0% — 28,190 Other 5.0 % – 14.6% 152 152 $ 123,455 $ 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 September 30, 2017 , the net assets of SEA-Vista were $249.7 million . During the nine months ended September 30, 2017 , the net income of SEA-Vista was $33.2 million , of which $16.3 million was attributable to noncontrolling interests. During the nine months ended September 30, 2016 , the net income of SEA-Vista was $32.4 million , of which $15.9 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 (see Note 1).

Multiemployer and Defined Benef

Multiemployer and Defined Benefit Pension Plans	9 Months Ended
	Sep. 30, 2017
Compensation and Retirement Disclosure [Abstract]
Multiemployer and Defined Benefit Pension Plans	MOPP. During the nine months ended September 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 September 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. ISH Retirement Plan. ISH sponsored a defined benefit pension plan (the “ISH Plan”) covering non-union employees prior to its acquisition by the Company on July 3, 2017 (see Note 2). The ISH Plan generally provided participants with benefits based on years of service and compensation levels for participants hired prior to September 1, 2006. From that date forward, the benefit was calculated prospectively under a cash balance formula with pay credits based on age plus service years and interest credits based on an as defined U.S. treasury rate. Effective July 3, 2017, in conjunction with the Plan, an amendment was made to the ISH Plan that fully vested all active participants as of January 1, 2017 and froze the retirement benefits effective August 31, 2017. As of August 31, 2017, all retirement benefits earned were fully preserved and will be paid in accordance with the ISH Plan and legal requirements. The following table sets forth the projected benefit obligation, plan assets and funded status associated with the ISH Plan as of September 30, 2017 (in thousands): Fair Value of Assets $ 37,464 Projected Benefit Obligation (37,227 ) Funded Status as of July 3, 2017 237 Net Pension Income July 3, 2017 through August 31, 2017 832 Funded Status as of September 30, 2017 (1) $ 1,069 _____________________ (1) Included in other assets in the accompanying condensed consolidated balance sheets. The significant assumptions used in determining the projected benefit obligation and net pension income were as follows: Discount rate 4.00 % Rate of increase in compensations levels 4.50 % CPI 3.00 % Cash balance interest credits (compounded annually) 4.50 % Expected long-term rate of return on plan assets 6.75 % The future benefit payments expected to be paid in each of the next five fiscal years are as follows (in thousands): 2017 (1) 909 2018 1,711 2019 1,804 2020 1,885 2021 1,982 _____________________ (1) July 3, 2017 through December 31, 2017 The following table sets forth the projected benefit obligation, plan assets and funded status associated with the ISH Plan as of September 30, 2017 (in thousands): Fair Value of Assets $ 37,464 Projected Benefit Obligation (37,227 ) Funded Status as of July 3, 2017 237 Net Pension Income July 3, 2017 through August 31, 2017 832 Funded Status as of September 30, 2017 (1) $ 1,069 _____________________ (1) Included in other assets in the accompanying condensed consolidated balance sheets.

Share Based Compensation

Share Based Compensation	9 Months Ended
	Sep. 30, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Share Based Compensation	ansactions in connection with the Company’s share based compensation plans during the nine months ended September 30, 2017 were as follows: Director stock awards granted 1,250 Employee Stock Purchase Plan (“ESPP”) shares issued 36,552 Restricted stock awards granted 146,850 Restricted stock awards canceled 2,177 Stock Option Activities: Outstanding as of December 31, 2016 1,639,865 Granted (1) 970,069 Exercised (386,417 ) Forfeited (3,374 ) Expired (541,783 ) Outstanding as of September 30, 2017 1,678,360 Shares available for future grants and ESPP purchases as of September 30, 2017 (2) 946,572 ______________________ (1) On June 2, 2017, the Company granted 846,353 stock options to existing option holders under make-whole provisions upon the Spin-off. (2) Shares available for future grants and ESPP purchases were adjusted on June 2, 2017 to reflect the Spin-off in accordance with make-whole provisions of the plans.

Commitments And Contingencies

Commitments And Contingencies	9 Months Ended
	Sep. 30, 2017
Commitments and Contingencies Disclosure [Abstract]
Commitments And Contingencies	e Company's capital commitments as of September 30, 2017 by year of expected payment were as follows (in thousands): Remainder of 2017 2018 2019 Total Shipping Services $ 4,689 $ 2,252 $ — $ 6,941 Inland River Services 1,577 1,137 529 3,243 $ 6,266 $ 3,389 $ 529 $ 10,184 Shipping Services’ capital commitments included two U.S.-flag harbor tugs and one foreign-flag RORO vessel. Inland River Services’ capital commitments included other equipment and various vessel improvements. Subsequent to September 30, 2017 , the Company committed to purchase additional equipment for $2.6 million . 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 asserted 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. The Company has continually taken the position that all of the B3 claims asserted against it, 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”). The deadline to appeal both of these orders has expired. As noted above, various civil actions involving the Company, ORM, and/or NRC and concerning the Deepwater Horizon clean-up were consolidated with the MDL, although the majority of them have since been dismissed or otherwise resolved. The remaining claim is the following: • 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”). Nathan Fitzgerald, the decedent in the Fitzgerald Action, was listed on the exhibit annexed to the Master MDL B3 Dismissal Order and so this claim against the Company remains pending. The Company is unable to estimate the potential exposure, if any, resulting from this matter, to the extent it remains viable, but believes it is without merit and does not expect that it 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 are 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	9 Months Ended
	Sep. 30, 2017
Segment Reporting [Abstract]
Segment Information	counting 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 15). 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 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 September 30, 2017 Operating Revenues: External customers 44,608 103,780 9,667 116 — 158,171 Intersegment — — 14 — (14 ) — 44,608 103,780 9,681 116 (14 ) 158,171 Costs and Expenses: Operating 35,388 65,866 6,068 — (64 ) 107,258 Administrative and general 3,141 9,612 2,960 180 4,638 20,531 Depreciation and amortization 6,329 13,516 206 — 450 20,501 44,858 88,994 9,234 180 5,024 148,290 Gains on Asset Dispositions, Net 5,136 73 — — — 5,209 Operating Income (Loss) 4,886 14,859 447 (64 ) (5,038 ) 15,090 Other Income (Expense): Foreign currency gains (losses), net 992 5 29 (12 ) (45 ) 969 Other, net — 59 — — 5 64 Equity in Earnings (Losses) of 50% or Less Owned Companies, Net of Tax (1,235 ) 1,493 100 130 — 488 Segment Profit 4,643 16,416 576 54 Other Income (Expense) not included in Segment Profit (19,229 ) Less Equity Earnings included in Segment Profit (488 ) Loss Before Taxes, Equity Earnings and Discontinued Operations (3,106 ) Inland River Services $’000 Shipping Services $’000 Witt O’Brien’s $’000 Other $’000 Corporate and Eliminations $’000 Total $’000 For the nine months ended September 30, 2017 Operating Revenues: External customers 124,921 243,442 23,665 348 — 392,376 Intersegment — — 85 — (85 ) — 124,921 243,442 23,750 348 (85 ) 392,376 Costs and Expenses: Operating 99,859 137,070 15,483 — (256 ) 252,156 Administrative and general 11,658 24,728 8,641 559 23,363 68,949 Depreciation and amortization 19,404 32,792 613 — 1,880 54,689 130,921 194,590 24,737 559 24,987 375,794 Gains (Losses) on Asset Dispositions and Impairments, Net 11,260 (342 ) — — — 10,918 Operating Income (Loss) 5,260 48,510 (987 ) (211 ) (25,072 ) 27,500 Other Income (Expense): Derivative gains, net — — — — 19,727 19,727 Foreign currency gains (losses), net 730 8 62 (12 ) 110 898 Other, net — 118 — (300 ) 250 68 Equity in Earnings (Losses) of 50% or Less Owned Companies, Net of Tax (4,877 ) 8,150 237 (581 ) — 2,929 Segment Profit (Loss) 1,113 56,786 (688 ) (1,104 ) Other Income (Expense) not included in Segment Profit (Loss) (37,860 ) Less Equity Earnings included in Segment Profit (Loss) (2,929 ) Income Before Taxes, Equity Earnings and Discontinued Operations 10,333 Capital Expenditures 32,901 66,137 60 — 208 99,306 As of September 30, 2017 Property and Equipment: Historical cost 444,582 1,008,093 1,227 — 29,532 1,483,434 Accumulated depreciation (175,669 ) (290,400 ) (915 ) — (20,065 ) (487,049 ) 268,913 717,693 312 — 9,467 996,385 Construction in progress 2,177 20,592 — — — 22,769 Net property and equipment 271,090 738,285 312 — 9,467 1,019,154 Investments, at Equity, and Advances to 50% or Less Owned Companies 65,738 53,388 782 55,479 — 175,387 Inventories 1,866 2,032 54 — — 3,952 Goodwill 2,415 1,852 28,506 — — 32,773 Intangible Assets 10,860 12,285 7,510 — — 30,655 Other current and long-term assets, excluding cash and near cash assets (1) 54,295 44,845 13,802 1,807 22,251 137,000 Segment Assets 406,264 852,687 50,966 57,286 Cash and near cash assets (1) 384,044 Total Assets 1,782,965 ______________________ (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 September 30, 2016 Operating Revenues: External customers 41,094 57,350 11,010 116 — 109,570 Intersegment — — 20 — (20 ) — 41,094 57,350 11,030 116 (20 ) 109,570 Costs and Expenses: Operating 31,496 28,542 6,618 — (83 ) 66,573 Administrative and general 3,982 6,675 3,423 410 6,441 20,931 Depreciation and amortization 6,308 8,216 432 — 908 15,864 41,786 43,433 10,473 410 7,266 103,368 Gains (Losses) on Asset Dispositions and Impairments, Net (597 ) 3 1 — — (593 ) Operating Income (Loss) (1,289 ) 13,920 558 (294 ) (7,286 ) 5,609 Other Income (Expense): Derivative losses, net — — — — (862 ) (862 ) Foreign currency gains (losses), net 410 (3 ) (24 ) (1 ) 36 418 Other, net (1 ) (5,534 ) — — 74 (5,461 ) Equity in Earnings (Losses) of 50% or Less Owned Companies, Net of Tax (171 ) (551 ) 91 (481 ) — (1,112 ) Segment Profit (Loss) (1,051 ) 7,832 625 (776 ) Other Income (Expense) not included in Segment Profit (Loss) (14,390 ) Less Equity Losses included in Segment Profit (Loss) 1,112 Loss Before Taxes, Equity Losses and Discontinued Operations (14,686 ) Inland River Services $’000 Shipping Services $’000 Witt O’Brien’s $’000 Other $’000 Corporate and Eliminations $’000 Total $’000 For the nine months ended September 30, 2016 Operating Revenues: External customers 114,522 170,025 29,356 366 — 314,269 Intersegment — — 104 — (104 ) — 114,522 170,025 29,460 366 (104 ) 314,269 Costs and Expenses: Operating 89,060 86,045 18,850 — (319 ) 193,636 Administrative and general 11,671 20,930 10,871 834 20,662 64,968 Depreciation and amortization 19,699 22,193 1,335 — 2,778 46,005 120,430 129,168 31,056 834 23,121 304,609 Gains (Losses) on Asset Dispositions and Impairments, Net 2,588 3 (1 ) — — 2,590 Operating Income (Loss) (3,320 ) 40,860 (1,597 ) (468 ) (23,225 ) 12,250 Other Income (Expense): Derivative losses, net — — — — (3,527 ) (3,527 ) Foreign currency gains (losses), net 2,865 (12 ) (124 ) (1 ) 84 2,812 Other, net (5 ) (6,461 ) — (6,723 ) 79 (13,110 ) Equity in Earnings (Losses) of 50% or Less Owned Companies, Net of Tax (4,626 ) (2,116 ) 277 (704 ) — (7,169 ) Segment Profit (Loss) (5,086 ) 32,271 (1,444 ) (7,896 ) Other Income (Expense) not included in Segment Profit (Loss) (63,851 ) Less Equity Losses included in Segment Profit (Loss) 7,169 Loss Before Taxes, Equity Losses and Discontinued Operations (65,426 ) Capital Expenditures 17,629 189,988 — — 208 207,825 As of September 30, 2016 Property and Equipment: Historical cost 392,698 592,132 2,829 — 30,711 1,018,370 Accumulated depreciation (161,023 ) (253,116 ) (2,483 ) — (17,427 ) (434,049 ) 231,675 339,016 346 — 13,284 584,321 Construction in progress 9,948 328,692 — — (1,191 ) 337,449 Net property and equipment 241,623 667,708 346 — 12,093 921,770 Investments, at Equity, and Advances to 50% or Less Owned Companies 80,004 57,366 551 60,131 — 198,052 Inventories 2,033 952 237 — — 3,222 Goodwill 2,427 1,852 48,124 — — 52,403 Intangible Assets 5,295 — 18,201 — — 23,496 Other current and long-term assets, excluding cash and near cash assets (1) 55,710 27,508 13,186 15,522 4,384 116,310 Segment Assets 387,092 755,386 80,645 75,653 Cash and near cash assets (1) 473,993 Discontinued Operations 1,164,887 Total Assets 2,954,133 ______________________ (1) Cash and near cash assets includes cash, cash equivalents, restricted cash, marketable securities and construction reserve funds.

Discontinued Operations (Notes)

Discontinued Operations (Notes)	9 Months Ended
	Sep. 30, 2017
Discontinued Operations and Disposal Groups [Abstract]
Disposal Groups, Including Discontinued Operations, Disclosure [Text Block]	e Company’s discontinued operations consist of SEACOR Marine and ICP as following the Spin-off and sale, respectively, the Company has no continuing involvement in either of these businesses (see Note 1). Summarized selected operating results of the Company’s discontinued operations were as follows (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 SEACOR Marine Operating Revenues $ — $ 54,125 $ 62,291 $ 171,275 Costs and Expenses: Operating — 41,159 65,888 134,254 Administrative and general — 10,588 29,682 34,915 Depreciation and amortization — 14,213 22,181 44,305 — 65,960 117,751 213,474 Gains (Losses) on Asset Dispositions and Impairments, Net — (29,233 ) 4,219 (49,970 ) Operating Loss — (41,068 ) (51,241 ) (92,169 ) Other Income (Expense), Net — (2,993 ) 1,780 (14,675 ) Income Tax Benefit — (15,263 ) (12,931 ) (35,831 ) Equity in Earnings (Losses) of 50% or Less Owned Companies, Net of Tax — 790 1,663 (364 ) Net Loss $ — $ (28,008 ) $ (34,867 ) $ (71,377 ) Net Loss Attributable to Noncontrolling Interests $ — $ (73 ) $ (1,892 ) $ (904 ) ICP Operating Revenues $ — $ 44,019 $ 78,061 $ 134,204 Costs and Expenses: Operating — 39,879 76,306 122,321 Administrative and general — 750 2,109 2,318 Depreciation and amortization — 1,055 2,354 3,172 — 41,684 80,769 127,811 Operating Income (Loss) — 2,335 (2,708 ) 6,393 Other Income, Net (including gain on sale of business) 18,223 537 20,558 3,014 Income Tax Expense 7,296 921 7,363 2,903 Net Income $ 10,927 $ 1,951 $ 10,487 $ 6,504 Net Income (Loss) Attributable to Noncontrolling Interests $ — $ 569 $ (539 ) $ 1,975 Eliminations Operating Revenues $ — $ (731 ) $ (1,176 ) $ (1,799 ) Costs and Expenses: Operating — (815 ) (1,289 ) (2,065 ) Administrative and general — (24 ) (42 ) (77 ) — (839 ) (1,331 ) (2,142 ) Operating Income — 108 155 343 Other Income, Net — 916 1,738 2,833 Income Tax Expense — 359 663 1,112 Net Income $ — $ 665 $ 1,230 $ 2,064 Loss from Discontinued Operations, Net of Tax $ — $ (25,392 ) $ (23,150 ) $ (62,809 )

Basis of Presentation and Acc22

Basis of Presentation and Accounting Policy (Policy)	9 Months Ended
	Sep. 30, 2017
Accounting Policies [Abstract]
Basis Of Consolidation	The condensed consolidated financial information for the three and nine months ended September 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 September 30, 2017 , its results of operations for the three and nine months ended September 30, 2017 and 2016 , its comprehensive income (loss) for the three and nine months ended September 30, 2017 and 2016 , its changes in equity for the nine months ended September 30, 2017 , and its cash flows for the nine months ended September 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 15). On July 3, 2017, the Company completed 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 a note from the buyer for $32.8 million after working capital adjustments resulting in a third quarter gain of $10.9 million , net of tax. On September 15, 2017, the Company received payment of the outstanding balance of the note, including accrued and unpaid interest. 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 15).
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 September 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 Articulated tug-barge - U.S.-flag 25 Dry-bulk carrier - 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 nine months ended September 30, 2017 , capitalized interest totaled $2.4 million .
Property, Plant and Equipment [Table Text Block]	As of September 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 Articulated tug-barge - U.S.-flag 25 Dry-bulk carrier - 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 nine months ended September 30, 2017 and 2016 , the Company recognized impairment charges of $0.4 million and $1.1 million , respectively, 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 nine months ended September 30, 2017 , the Company recognized an impairment charge of $0.9 million , net of tax, related to its 50% or less owned companies. During the nine months ended September 30, 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 nine months ended September 30, 2017 , the Company’s effective income tax rate of (121.6)% was primarily due to the reversal of a provision related to potential tax exposures surrounding the spin-off of Era Group Inc. (“Era Group”) by means of a dividend to SEACOR’s shareholders of all the issued and outstanding common stock of Era Group (the “Era Spin-off”) and taxes not provided on income attributable to noncontrolling interests (see Note 6).
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 nine months ended September 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 (11,126 ) (11,219 ) Amortization of deferred gains included in gains (losses) on asset dispositions and impairments, net (1,764 ) (1,816 ) Other — (1,697 ) Balance at end of period $ 77,253 $ 86,881
Schedule Of Deferred Gain Activity [Table Text Block]	Deferred gain activity related to these transactions for the nine months ended September 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 (11,126 ) (11,219 ) Amortization of deferred gains included in gains (losses) on asset dispositions and impairments, net (1,764 ) (1,816 ) Other — (1,697 ) Balance at end of period $ 77,253 $ 86,881
Accumulated Other Comprehensive Loss	Accumulated Other Comprehensive Income (Loss). The components of accumulated other comprehensive income (loss) were as follows (in thousands): SEACOR Holdings Inc. Stockholders’ Equity Noncontrolling Interests Foreign Currency Translation Adjustments Derivative Gains 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) 1,994 (260 ) (6 ) 1,728 153 13 (5 ) $ 1,889 Income tax (expense) benefit (698 ) 91 2 (605 ) — — — (605 ) Nine Months Ended September 30, 2017 $ (266 ) $ — $ — $ (266 ) $ (1,460 ) $ (4 ) $ (2 ) $ 1,284
Earnings Per Common Share of SEACOR	Loss) Per Share. Basic earnings (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 earnings (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 earnings (loss) per common share of SEACOR were as follows (in thousands, except share data): Three Months Ended September 30, Nine Months Ended September 30, Net Income (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 $ 17,561 17,508,770 $ 1.00 $ (11,164 ) 17,265,140 $ (0.65 ) Effect of Dilutive Share Awards: Options and Restricted Stock (1) — 129,054 — 245,420 Convertible Notes (2) — — — — Diluted Weighted Average Common Shares Outstanding $ 17,561 17,637,824 $ 1.00 $ (11,164 ) 17,510,560 $ (0.64 ) 2016 Basic Weighted Average Common Shares Outstanding $ (39,803 ) 16,943,647 $ (2.35 ) $ (122,148 ) 16,896,751 $ (7.23 ) Effect of Dilutive Share Awards: Options and Restricted Stock (3) — — — — Convertible Notes (4) — — — — Diluted Weighted Average Common Shares Outstanding $ (39,803 ) 16,943,647 $ (2.35 ) $ (122,148 ) 16,896,751 $ (7.23 ) ______________________ (1) For the three and nine months ended September 30, 2017 , diluted earnings (loss) per common share of SEACOR excluded 1,727,132 and 2,638,753 , 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 nine months ended September 30, 2017 , diluted earnings (loss) per common share of SEACOR excluded 1,889,027 and 2,488,460 , 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 nine months ended September 30, 2016 , diluted loss per common share of SEACOR excluded 2,041,652 and 2,041,652 , respectively, of certain share awards as the effect of their inclusion in the computation would be anti-dilutive. (4) For the three and nine months ended September 30, 2016 , diluted loss per common share of SEACOR excluded 2,382,626 and 2,910,688 , 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 earnings (loss) per common share of SEACOR were as follows (in thousands, except share data): Three Months Ended September 30, Nine Months Ended September 30, Net Income (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 $ 17,561 17,508,770 $ 1.00 $ (11,164 ) 17,265,140 $ (0.65 ) Effect of Dilutive Share Awards: Options and Restricted Stock (1) — 129,054 — 245,420 Convertible Notes (2) — — — — Diluted Weighted Average Common Shares Outstanding $ 17,561 17,637,824 $ 1.00 $ (11,164 ) 17,510,560 $ (0.64 ) 2016 Basic Weighted Average Common Shares Outstanding $ (39,803 ) 16,943,647 $ (2.35 ) $ (122,148 ) 16,896,751 $ (7.23 ) Effect of Dilutive Share Awards: Options and Restricted Stock (3) — — — — Convertible Notes (4) — — — — Diluted Weighted Average Common Shares Outstanding $ (39,803 ) 16,943,647 $ (2.35 ) $ (122,148 ) 16,896,751 $ (7.23 ) ______________________ (1) For the three and nine months ended September 30, 2017 , diluted earnings (loss) per common share of SEACOR excluded 1,727,132 and 2,638,753 , 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 nine months ended September 30, 2017 , diluted earnings (loss) per common share of SEACOR excluded 1,889,027 and 2,488,460 , 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 nine months ended September 30, 2016 , diluted loss per common share of SEACOR excluded 2,041,652 and 2,041,652 , respectively, of certain share awards as the effect of their inclusion in the computation would be anti-dilutive. (4) For the three and nine months ended September 30, 2016 , diluted loss per common share of SEACOR excluded 2,382,626 and 2,910,688 , 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 barge pooling arrangements may result in a gross presentation of operating revenues and expenses for pooled third party equipment resulting in a material increase in operating revenues and expenses, however operating income would remain unchanged. On February 25, 2016, the FASB issued a comprehensive new leasing standard, which is meant to improve 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 unit’s 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.

Business Acquisitions (Tables)

Business Acquisitions (Tables) $ in Thousands	9 Months Ended
	Sep. 30, 2017USD ($)
Business Combinations [Abstract]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Marketable Securities	$ 13
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Receivables	15,420
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Other	2,055
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Assets	10,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment	15,478
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles	12,658
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Other Noncurrent Assets	(17,863)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Other	(18,183)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Long-term Debt	(28,725)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Liabilities Noncurrent	3,939
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Other	(42)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net	(5,250)
Cash Acquired from Acquisition	$ 15,700

Income Taxes (Tables)

Income Taxes (Tables)	9 Months Ended
	Sep. 30, 2017
Income Tax Disclosure [Abstract]
Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]	The following table reconciles the difference between the statutory federal income tax rate for the Company and the effective income tax rate on continuing operations for the nine months ended September 30, 2017 : Statutory rate 35.0 % Income subject to tonnage tax (3.4 )% Reversal of uncertain tax position (97.9 )% Non-deductible expenses 1.3 % Noncontrolling interests (55.1 )% Losses of foreign subsidiaries not benefited (13.1 )% State taxes 5.3 % Share award plans 6.3 % (121.6 )%

Fair Value Measurements Fair Va

Fair Value Measurements Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2017
Fair Value Disclosures [Abstract]
Fair Value Measurements	he 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 September 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) $ 62,606 $ — $ — Construction reserve funds 51,846 — — ______________________ (1) Marketable security losses, net include unrealized losses of $12.5 million and $9.6 million for the three months ended September 30, 2017 and 2016 , respectively, related to marketable security positions held by the Company as of September 30, 2017 . Marketable security losses, net include unrealized losses of $12.8 million and $53.0 million for the nine months ended September 30, 2017 and 2016 , respectively, related to marketable security positions held by the Company as of September 30, 2017 . The estimated fair values of the Company’s other financial assets and liabilities as of September 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 $ 269,592 $ 269,592 $ — $ — 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) 2,773 950 1,741 — LIABILITIES Long-term debt, including current portion (1) $ 739,552 $ — $ 749,775 $ — ______________________ (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. The Company’s other assets and liabilities that were measured at fair value during the nine months ended September 30, 2017 were as follows (in thousands): Level 1 Level 2 Level 3 ASSETS Investments, at equity, and advances in 50% or less owned companies $ — $ 6,000 $ — Investments, at equity and advances in 50% or less owned companies. During the nine months ended September 30, 2017 , the Company identified indicators of impairment for its investment in VA&E based on their recent financial results. The Company evaluated the fair value of VA&E and determined that its assets and liabilities were carried at fair value except for property, plant and equipment and certain deferred tax assets. Based on this evaluation, the Company concluded its carrying value was in excess of fair value and the impairment was other than temporary resulting in an impairment charge of $0.9 million , net of tax, of its equity investment.
Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis	The Company’s financial assets and liabilities as of September 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) $ 62,606 $ — $ — Construction reserve funds 51,846 — — ______________________ (1) Marketable security losses, net include unrealized losses of $12.5 million and $9.6 million for the three months ended September 30, 2017 and 2016 , respectively, related to marketable security positions held by the Company as of September 30, 2017 . Marketable security losses, net include unrealized losses of $12.8 million and $53.0 million for the nine months ended September 30, 2017 and 2016 , respectively, related to marketable security positions held by the Company as of September 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 September 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 $ 269,592 $ 269,592 $ — $ — 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) 2,773 950 1,741 — LIABILITIES Long-term debt, including current portion (1) $ 739,552 $ — $ 749,775 $ — ______________________ (1) The estimated fair value includes the embedded conversion options on the Company’s 2.5% and 3.0% Convertible Senior Notes.
Fair Value Measurements, Nonrecurring [Table Text Block]	The Company’s other assets and liabilities that were measured at fair value during the nine months ended September 30, 2017 were as follows (in thousands): Level 1 Level 2 Level 3 ASSETS Investments, at equity, and advances in 50% or less owned companies $ — $ 6,000 $ —

Noncontrolling Interests in S26

Noncontrolling Interests in Subsidiaries (Tables)	9 Months Ended
	Sep. 30, 2017
Noncontrolling Interest [Abstract]
Noncontrolling Interests in Subsidiaries [Table Text Block]	Noncontrolling interests in the Company’s consolidated subsidiaries were as follows (in thousands): Noncontrolling Interests September 30, 2017 December 31, 2016 Inland River Services: Other 3.0 % – 51.8% $ 959 $ 980 Shipping Services: SEA-Vista 49% 122,344 106,054 Discontinued Operations 1.8 % – 50.0% — 28,190 Other 5.0 % – 14.6% 152 152 $ 123,455 $ 135,376

Multiemployer and Defined Ben27

Multiemployer and Defined Benefit Pension Plans Multiemployer and Defined Benefit Pension Plans (Tables)	9 Months Ended
	Sep. 30, 2017
Defined Benefit Pension Plans and Defined Benefit Postretirement Plans Disclosure [Abstract]
Schedule of Defined Benefit Plans Disclosures [Table Text Block]	The following table sets forth the projected benefit obligation, plan assets and funded status associated with the ISH Plan as of September 30, 2017 (in thousands): Fair Value of Assets $ 37,464 Projected Benefit Obligation (37,227 ) Funded Status as of July 3, 2017 237 Net Pension Income July 3, 2017 through August 31, 2017 832 Funded Status as of September 30, 2017 (1) $ 1,069 _____________________ (1) Included in other assets in the accompanying condensed consolidated balance sheets. The significant assumptions used in determining the projected benefit obligation and net pension income were as follows: Discount rate 4.00 % Rate of increase in compensations levels 4.50 % CPI 3.00 % Cash balance interest credits (compounded annually) 4.50 % Expected long-term rate of return on plan assets 6.75 % The future benefit payments expected to be paid in each of the next five fiscal years are as follows (in thousands): 2017 (1) 909 2018 1,711 2019 1,804 2020 1,885 2021 1,982 _____________________ (1) July 3, 2017 through December 31, 2017

Share Based Compensation (Table

Share Based Compensation (Tables)	9 Months Ended
	Sep. 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 nine months ended September 30, 2017 were as follows: Director stock awards granted 1,250 Employee Stock Purchase Plan (“ESPP”) shares issued 36,552 Restricted stock awards granted 146,850 Restricted stock awards canceled 2,177 Stock Option Activities: Outstanding as of December 31, 2016 1,639,865 Granted (1) 970,069 Exercised (386,417 ) Forfeited (3,374 ) Expired (541,783 ) Outstanding as of September 30, 2017 1,678,360 Shares available for future grants and ESPP purchases as of September 30, 2017 (2) 946,572 ______________________ (1) On June 2, 2017, the Company granted 846,353 stock options to existing option holders under make-whole provisions upon the Spin-off. (2) Shares available for future grants and ESPP purchases were adjusted on June 2, 2017 to reflect the Spin-off in accordance with make-whole provisions of the plans.

Commitments And Contingencies C

Commitments And Contingencies Capital Commitments (Tables)	9 Months Ended
	Sep. 30, 2017
Commitments and Contingencies Disclosure [Abstract]
Unrecorded Unconditional Purchase Obligations Disclosure [Table Text Block]	The Company's capital commitments as of September 30, 2017 by year of expected payment were as follows (in thousands): Remainder of 2017 2018 2019 Total Shipping Services $ 4,689 $ 2,252 $ — $ 6,941 Inland River Services 1,577 1,137 529 3,243 $ 6,266 $ 3,389 $ 529 $ 10,184

Segment Information Segment Inf

Segment Information Segment Information (Tables)	9 Months Ended
	Sep. 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 September 30, 2017 Operating Revenues: External customers 44,608 103,780 9,667 116 — 158,171 Intersegment — — 14 — (14 ) — 44,608 103,780 9,681 116 (14 ) 158,171 Costs and Expenses: Operating 35,388 65,866 6,068 — (64 ) 107,258 Administrative and general 3,141 9,612 2,960 180 4,638 20,531 Depreciation and amortization 6,329 13,516 206 — 450 20,501 44,858 88,994 9,234 180 5,024 148,290 Gains on Asset Dispositions, Net 5,136 73 — — — 5,209 Operating Income (Loss) 4,886 14,859 447 (64 ) (5,038 ) 15,090 Other Income (Expense): Foreign currency gains (losses), net 992 5 29 (12 ) (45 ) 969 Other, net — 59 — — 5 64 Equity in Earnings (Losses) of 50% or Less Owned Companies, Net of Tax (1,235 ) 1,493 100 130 — 488 Segment Profit 4,643 16,416 576 54 Other Income (Expense) not included in Segment Profit (19,229 ) Less Equity Earnings included in Segment Profit (488 ) Loss Before Taxes, Equity Earnings and Discontinued Operations (3,106 ) Inland River Services $’000 Shipping Services $’000 Witt O’Brien’s $’000 Other $’000 Corporate and Eliminations $’000 Total $’000 For the nine months ended September 30, 2017 Operating Revenues: External customers 124,921 243,442 23,665 348 — 392,376 Intersegment — — 85 — (85 ) — 124,921 243,442 23,750 348 (85 ) 392,376 Costs and Expenses: Operating 99,859 137,070 15,483 — (256 ) 252,156 Administrative and general 11,658 24,728 8,641 559 23,363 68,949 Depreciation and amortization 19,404 32,792 613 — 1,880 54,689 130,921 194,590 24,737 559 24,987 375,794 Gains (Losses) on Asset Dispositions and Impairments, Net 11,260 (342 ) — — — 10,918 Operating Income (Loss) 5,260 48,510 (987 ) (211 ) (25,072 ) 27,500 Other Income (Expense): Derivative gains, net — — — — 19,727 19,727 Foreign currency gains (losses), net 730 8 62 (12 ) 110 898 Other, net — 118 — (300 ) 250 68 Equity in Earnings (Losses) of 50% or Less Owned Companies, Net of Tax (4,877 ) 8,150 237 (581 ) — 2,929 Segment Profit (Loss) 1,113 56,786 (688 ) (1,104 ) Other Income (Expense) not included in Segment Profit (Loss) (37,860 ) Less Equity Earnings included in Segment Profit (Loss) (2,929 ) Income Before Taxes, Equity Earnings and Discontinued Operations 10,333 Capital Expenditures 32,901 66,137 60 — 208 99,306 As of September 30, 2017 Property and Equipment: Historical cost 444,582 1,008,093 1,227 — 29,532 1,483,434 Accumulated depreciation (175,669 ) (290,400 ) (915 ) — (20,065 ) (487,049 ) 268,913 717,693 312 — 9,467 996,385 Construction in progress 2,177 20,592 — — — 22,769 Net property and equipment 271,090 738,285 312 — 9,467 1,019,154 Investments, at Equity, and Advances to 50% or Less Owned Companies 65,738 53,388 782 55,479 — 175,387 Inventories 1,866 2,032 54 — — 3,952 Goodwill 2,415 1,852 28,506 — — 32,773 Intangible Assets 10,860 12,285 7,510 — — 30,655 Other current and long-term assets, excluding cash and near cash assets (1) 54,295 44,845 13,802 1,807 22,251 137,000 Segment Assets 406,264 852,687 50,966 57,286 Cash and near cash assets (1) 384,044 Total Assets 1,782,965 ______________________ (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 September 30, 2016 Operating Revenues: External customers 41,094 57,350 11,010 116 — 109,570 Intersegment — — 20 — (20 ) — 41,094 57,350 11,030 116 (20 ) 109,570 Costs and Expenses: Operating 31,496 28,542 6,618 — (83 ) 66,573 Administrative and general 3,982 6,675 3,423 410 6,441 20,931 Depreciation and amortization 6,308 8,216 432 — 908 15,864 41,786 43,433 10,473 410 7,266 103,368 Gains (Losses) on Asset Dispositions and Impairments, Net (597 ) 3 1 — — (593 ) Operating Income (Loss) (1,289 ) 13,920 558 (294 ) (7,286 ) 5,609 Other Income (Expense): Derivative losses, net — — — — (862 ) (862 ) Foreign currency gains (losses), net 410 (3 ) (24 ) (1 ) 36 418 Other, net (1 ) (5,534 ) — — 74 (5,461 ) Equity in Earnings (Losses) of 50% or Less Owned Companies, Net of Tax (171 ) (551 ) 91 (481 ) — (1,112 ) Segment Profit (Loss) (1,051 ) 7,832 625 (776 ) Other Income (Expense) not included in Segment Profit (Loss) (14,390 ) Less Equity Losses included in Segment Profit (Loss) 1,112 Loss Before Taxes, Equity Losses and Discontinued Operations (14,686 ) Inland River Services $’000 Shipping Services $’000 Witt O’Brien’s $’000 Other $’000 Corporate and Eliminations $’000 Total $’000 For the nine months ended September 30, 2016 Operating Revenues: External customers 114,522 170,025 29,356 366 — 314,269 Intersegment — — 104 — (104 ) — 114,522 170,025 29,460 366 (104 ) 314,269 Costs and Expenses: Operating 89,060 86,045 18,850 — (319 ) 193,636 Administrative and general 11,671 20,930 10,871 834 20,662 64,968 Depreciation and amortization 19,699 22,193 1,335 — 2,778 46,005 120,430 129,168 31,056 834 23,121 304,609 Gains (Losses) on Asset Dispositions and Impairments, Net 2,588 3 (1 ) — — 2,590 Operating Income (Loss) (3,320 ) 40,860 (1,597 ) (468 ) (23,225 ) 12,250 Other Income (Expense): Derivative losses, net — — — — (3,527 ) (3,527 ) Foreign currency gains (losses), net 2,865 (12 ) (124 ) (1 ) 84 2,812 Other, net (5 ) (6,461 ) — (6,723 ) 79 (13,110 ) Equity in Earnings (Losses) of 50% or Less Owned Companies, Net of Tax (4,626 ) (2,116 ) 277 (704 ) — (7,169 ) Segment Profit (Loss) (5,086 ) 32,271 (1,444 ) (7,896 ) Other Income (Expense) not included in Segment Profit (Loss) (63,851 ) Less Equity Losses included in Segment Profit (Loss) 7,169 Loss Before Taxes, Equity Losses and Discontinued Operations (65,426 ) Capital Expenditures 17,629 189,988 — — 208 207,825 As of September 30, 2016 Property and Equipment: Historical cost 392,698 592,132 2,829 — 30,711 1,018,370 Accumulated depreciation (161,023 ) (253,116 ) (2,483 ) — (17,427 ) (434,049 ) 231,675 339,016 346 — 13,284 584,321 Construction in progress 9,948 328,692 — — (1,191 ) 337,449 Net property and equipment 241,623 667,708 346 — 12,093 921,770 Investments, at Equity, and Advances to 50% or Less Owned Companies 80,004 57,366 551 60,131 — 198,052 Inventories 2,033 952 237 — — 3,222 Goodwill 2,427 1,852 48,124 — — 52,403 Intangible Assets 5,295 — 18,201 — — 23,496 Other current and long-term assets, excluding cash and near cash assets (1) 55,710 27,508 13,186 15,522 4,384 116,310 Segment Assets 387,092 755,386 80,645 75,653 Cash and near cash assets (1) 473,993 Discontinued Operations 1,164,887 Total Assets 2,954,133 ______________________ (1) Cash and near cash assets includes cash, cash equivalents, restricted cash, marketable securities and construction reserve funds.

Discontinued Operations (Tables

Discontinued Operations (Tables)	9 Months Ended
	Sep. 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 September 30, Nine Months Ended September 30, 2017 2016 2017 2016 SEACOR Marine Operating Revenues $ — $ 54,125 $ 62,291 $ 171,275 Costs and Expenses: Operating — 41,159 65,888 134,254 Administrative and general — 10,588 29,682 34,915 Depreciation and amortization — 14,213 22,181 44,305 — 65,960 117,751 213,474 Gains (Losses) on Asset Dispositions and Impairments, Net — (29,233 ) 4,219 (49,970 ) Operating Loss — (41,068 ) (51,241 ) (92,169 ) Other Income (Expense), Net — (2,993 ) 1,780 (14,675 ) Income Tax Benefit — (15,263 ) (12,931 ) (35,831 ) Equity in Earnings (Losses) of 50% or Less Owned Companies, Net of Tax — 790 1,663 (364 ) Net Loss $ — $ (28,008 ) $ (34,867 ) $ (71,377 ) Net Loss Attributable to Noncontrolling Interests $ — $ (73 ) $ (1,892 ) $ (904 ) ICP Operating Revenues $ — $ 44,019 $ 78,061 $ 134,204 Costs and Expenses: Operating — 39,879 76,306 122,321 Administrative and general — 750 2,109 2,318 Depreciation and amortization — 1,055 2,354 3,172 — 41,684 80,769 127,811 Operating Income (Loss) — 2,335 (2,708 ) 6,393 Other Income, Net (including gain on sale of business) 18,223 537 20,558 3,014 Income Tax Expense 7,296 921 7,363 2,903 Net Income $ 10,927 $ 1,951 $ 10,487 $ 6,504 Net Income (Loss) Attributable to Noncontrolling Interests $ — $ 569 $ (539 ) $ 1,975 Eliminations Operating Revenues $ — $ (731 ) $ (1,176 ) $ (1,799 ) Costs and Expenses: Operating — (815 ) (1,289 ) (2,065 ) Administrative and general — (24 ) (42 ) (77 ) — (839 ) (1,331 ) (2,142 ) Operating Income — 108 155 343 Other Income, Net — 916 1,738 2,833 Income Tax Expense — 359 663 1,112 Net Income $ — $ 665 $ 1,230 $ 2,064 Loss from Discontinued Operations, Net of Tax $ — $ (25,392 ) $ (23,150 ) $ (62,809 )

Basis of Presentation and Acc32

Basis of Presentation and Accounting Policies Discontinued Operations (Details) - Illinois Corn Processing LLC [Member] - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2017	Jul. 03, 2017
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Noncontrolling Interest, Ownership Percentage by Parent		70.00%
Proceeds from Divestiture of Businesses	$ 21
Proceeds from Issuance of Secured Debt	32.8
Discontinued Operation, Gain (Loss) on Disposal of Discontinued Operation, Net of Tax	$ 10.9

Basis of Presentation and Acc33

Basis of Presentation and Accounting Policies Property and Equipment (Details) $ in Millions	9 Months Ended
	Sep. 30, 2017USD ($)
Property, Plant and Equipment [Line Items]
Capitalized Interest Costs, Including Allowance for Funds Used During Construction	$ 2.4
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
U.S.-flag Articulated tug-barge [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	25 years
U.S.-flag dry-bulk carrier [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 Acc34

Basis of Presentation and Accounting Policies Impairments of Long-Lived Assets (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Property, Plant and Equipment [Abstract]
Asset Impairment Charges	$ 0.4	$ (1.1)

Basis of Presentation and Acc35

Basis of Presentation and Accounting Policies Income Taxes (Details)	9 Months Ended
	Sep. 30, 2017
Income Tax Disclosure [Abstract]
Effective Income Tax Rate Reconciliation, Percent	(121.60%)

Basis of Presentation and Acc36

Basis of Presentation and Accounting Policies Deferred Gains (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016	Dec. 31, 2015
Deferred Gains	$ 77,253	$ 86,881	$ 82,423	$ 92,610
Increase (Decrease) in Deferred Charges	7,720	9,003
Amortization of Deferred Gains	0	1,697
Operating Expense [Member]
Amortization of Deferred Gains	11,126	11,219
Gain (Loss) on Asset Dispositions and Impairments, Net [Member]
Amortization of Deferred Gains	$ 1,764	$ 1,816

Basis of Presentation and Acc37

Basis of Presentation and Accounting Policies Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Accumulated Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Net of Tax	$ (266)		$ (266)		$ (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	0		0		4
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, before Tax, Portion Attributable to Parent			1,994
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			(6)
Other Comprehensive Income (Loss), before Tax, Portion Attributable to Parent			1,728
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	430	$ 369	1,889	$ (8,318)
Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Tax, Portion Attributable to Parent			(698)
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			2
Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent			(605)
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	151	182	605	(2,612)
Accumulated other comprehensive loss, net of tax	(266)		(266)		(11,514)
Other Comprehensive Income (Loss), Net of Tax	279	$ 187	1,284	$ (5,706)
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
SEACOR Marine Holdings Inc. [Member]
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, before Tax, Portion Attributable to Parent			10,031
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, before Tax, Portion Attributable to Parent			94
Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Adjustment, before Tax, Portion Attributable to Parent			0
Other Comprehensive Income (Loss), before Tax, Portion Attributable to Parent			$ 10,125

Basis of Presentation and Acc38

Basis of Presentation and Accounting Policies Earning Per Common Share (Details) - USD ($)	3 Months Ended			6 Months Ended	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Jun. 30, 2016	Jun. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Net income (loss) attributable to SEACOR Holdings Inc.	$ 17,561,000	$ (39,803,000)			$ (11,164,000)	$ (122,148,000)
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	$ 17,561,000	$ (39,803,000)			$ (11,164,000)	$ (122,148,000)
Weighted Average Number of Shares Outstanding, Basic	17,508,770	16,943,647			17,265,140	16,896,751
Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements	129,054	0			245,420	0
Incremental Common Shares Attributable to Dilutive Effect of Conversion of Debt Securities	0	0			0	0
Weighted Average Number of Shares Outstanding, Diluted	17,637,824	16,943,647			17,510,560	16,896,751
Basic Earnings (Loss) Per Common Share of SEACOR Holdings Inc.	$ 1	$ (2.35)			$ (0.65)	$ (7.23)
Diluted Earnings (Loss) Per Common Share of SEACOR Holdings Inc.	$ 1	$ (2.35)			$ (0.64)	$ (7.23)
Stock Compensation Plan [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	1,727,132	2,041,652			2,638,753	2,041,652
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%
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		1,825,326	2,801,147
Two Point Five Percentage Convertible Notes [Member]
Incremental Common Shares Attributable to Dilutive Effect of Conversion of Debt Securities					1,758,107
Debt Instrument, Interest Rate, Stated Percentage	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	1,889,027		2,382,626	2,910,688	2,488,460

Business Acquisitions (Details)

Business Acquisitions (Details) $ in Thousands	3 Months Ended
	Sep. 30, 2017USD ($)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Marketable Securities	$ 13
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Long-term Debt	28,725
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Receivables	15,420
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Other	2,055
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Assets	10,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment	15,478
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles	12,658
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Other Noncurrent Assets	(17,863)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Other	18,183
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Liabilities Noncurrent	(3,939)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Other	42
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net	(5,250)
ISH [Member]
Payments to Acquire Businesses, Gross	10,500
Debt Conversion, Converted Instrument, Amount	18,100
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Long-term Debt	$ (28,700)

Equipment Acquisitions, Dispo40

Equipment Acquisitions, Dispositions and Depreciation and Impairment Policies (Narrative) (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2017USD ($)equipment	Sep. 30, 2016USD ($)
Property, Plant and Equipment [Line Items]
Payments to Acquire Property, Plant, and Equipment | $	$ 99,306	$ 207,825
Sales Price Of Equipment | $	27,600
Gain (Loss) on Disposition of Property Plant Equipment | $	17,600
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	2
Inland River Towboat [Member]
Property, Plant and Equipment [Line Items]
Number of Equipment Acquired | equipment	3
Number Of Equipments Sold | equipment	2
U.S. Flag Articulated Tug-Barge [Member]
Property, Plant and Equipment [Line Items]
Number of Equipment Acquired | 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 | $	$ 9,900
Amortization Of Deferred Gains Included In Gains On Asset Dispositions And Impairments, Net | $	1,764	$ 1,816
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 A41

Investments, At Equity, And Advances To 50% Or Less Owned Companies (Narrative) (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Jun. 30, 2017
Schedule Of Equity Method Investments [Line Items]
Proceeds from Divestiture of Interest in Consolidated Subsidiaries	$ 5,000	$ 0
Return of investments and advances from 50% or less owned companies	9,676	$ 8,361
SCFCo Holdings [Member]
Schedule Of Equity Method Investments [Line Items]
Partners' Capital Account, Contributions	400
Payments for Advance to Affiliate	500
Proceeds from Collection of Advance to Affiliate	(1,700)
Partners' Capital, Other	4,200
Outstanding Working Capital Advances At End Of Period	27,400
Trailer Bridge Inc [Member]
Schedule Of Equity Method Investments [Line Items]
Payments for Advance to Affiliate	2,000
Proceeds from Collection of Advance to Affiliate	2,100
Outstanding Working Capital Advances At End Of Period	3,900
Seajon [Member]
Schedule Of Equity Method Investments [Line Items]
Proceeds from Equity Method Investment, Dividends or Distributions, Return of Capital	3,500
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
RF Vessel Holdings [Member]
Schedule Of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage			50.00%
Proceeds from Divestiture of Interest in Consolidated Subsidiaries	1,900
Golfo de Mexico [Member]
Schedule Of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage			50.00%
Proceeds from Divestiture of Interest in Consolidated Subsidiaries	3,100
VA&E [Member]
Schedule Of Equity Method Investments [Line Items]
Outstanding Working Capital Advances At End Of Period	7,500
Equity Method Investment, Other than Temporary Impairment	900
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
Proceeds from Collection of Advance to Affiliate	2,000
Outstanding Working Capital Advances At End Of Period	2,000
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			9 Months Ended
	Dec. 31, 2017USD ($)	Sep. 30, 2017USD ($)$ / sharesshares	Sep. 30, 2016USD ($)shares	Sep. 30, 2017USD ($)$ / sharesshares	Sep. 30, 2016USD ($)shares	Jul. 03, 2017USD ($)	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		$ 77,400		$ 77,400
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Long-term Debt		28,725		28,725
Letters of Credit Outstanding, Amount		$ 27,200		$ 27,200
Incremental Common Shares Attributable to Dilutive Effect of Conversion of Debt Securities | shares		0	0	0	0
Gain (Loss) on Extinguishment of Debt		$ 3	$ 557	$ (94)	$ 5,395
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%
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%
Debt Instrument, Repurchased Face Amount		$ 61,700		$ 61,700
Convertible Debt		95,500		$ 95,500
Debt Instrument, Convertible, Conversion Ratio				18.4176
Incremental Common Shares Attributable to Dilutive Effect of Conversion of Debt Securities | shares				1,758,107
Debt Instrument, Repurchase Amount		61,900		$ 61,900
Gain (Loss) on Extinguishment of Debt				100
Other Debt Obligations [Member]
Debt Instrument [Line Items]
Repayments of long-term debt				300
SEACOR Marine Holdings Inc. [Member]
Debt Instrument [Line Items]
Letters of Credit Outstanding, Amount		16,700		16,700
Guarantor Obligations, Maximum Exposure, Undiscounted		84,900		84,900
Guaranty Fee Income		100	$ 100	500	$ 600
Sea-Vista [Member] | Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Proceeds from Lines of Credit				38,900
Repayments of Lines of Credit				45,900
Line of Credit Facility, Current Borrowing Capacity		$ 21,000		21,000
Sea-Vista [Member] | Term A-1 Loan [Member]
Debt Instrument [Line Items]
Repayments of long-term debt				3,600
Sea-Vista [Member] | Term A-2 Loan [Member]
Debt Instrument [Line Items]
Repayments of long-term debt				3,000
ISH [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity						$ 25,000
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage		0.50%
Debt Issuance Costs, Gross						100
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Long-term Debt		$ (28,700)		(28,700)
ISH [Member] | Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Debt Instrument, Unused Borrowing Capacity, Amount						5,000
Repayments of long-term debt				5,000
Line of Credit Facility, Current Borrowing Capacity		$ 5,000		5,000
ISH [Member] | ISH Term Loan [Member]
Debt Instrument [Line Items]
Debt Instrument, Unused Borrowing Capacity, Amount						$ 20,000
Repayments of long-term debt				$ 7,200
ISH [Member] | Other Debt Obligations [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		7.00%		7.00%
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Long-term Debt		$ 3,900		$ 3,900
Subsequent Event [Member] | Sea-Vista [Member] | Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Proceeds from Lines of Credit	$ 6,000
Minimum [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		60,500		60,500
Additional Paid-In Capital [Member] | Two Point Five Percentage Convertible Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Repurchase Amount		$ 1,400		$ 1,400

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2017	Dec. 31, 2013
Income Tax Disclosure [Abstract]
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	35.00%
Effective Income Tax Rate Reconciliation,Other Reconciling Items, Percent	(3.40%)
Effective Income Tax Rate Reconciliation, Tax Contingency, Domestic, Percent	(97.90%)
Effective Income Tax Rate Reconciliation, Nondeductible Expense, Percent	1.30%
Effective Income Tax Rate Reconciliation, Noncontrolling Interest Income (Loss), Percent	(55.10%)
Effective Income Tax Rate Reconciliation, Deduction, Other, Percent	(13.10%)
Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Percent	5.30%
Effective Income Tax Rate Reconciliation, Deduction, Employee Stock Ownership Plan Dividend, Percent	6.30%
Effective Income Tax Rate Reconciliation, Percent	(121.60%)
Liability for Uncertainty in Income Taxes, Noncurrent		$ 10.1
Unrecognized Tax Benefits, Income Tax Penalties and Interest Expense	$ 2

Derivative Instruments And He44

Derivative Instruments And Hedging Strategies (Recognized Gains (Losses) On Derivative Instruments Not Designated As Hedging Instruments) (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Derivative [Line Items]
Derivative gains (losses), net	$ 19,727	$ (3,527)
Forward Currency Exchange, Option And Future Contracts [Member]
Derivative [Line Items]
Derivative gains (losses), net	291	(186)
Commodity swap, option and future contracts, exchange traded
Derivative [Line Items]
Derivative gains (losses), net	0	(13)
Three Point Seven Five Percentage Convertible Notes [Member]
Derivative [Line Items]
Embedded Derivative, Gain on Embedded Derivative	$ 19,436	$ (3,328)
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		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Construction Reserve Funds	$ 51,846		$ 51,846		$ 75,753
Marketable security gains (losses), net	(12,500)	$ (9,600)
Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	62,606		62,606
Construction Reserve Funds	51,846		51,846
Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	0		0
Construction Reserve Funds	0		0
Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	0		0
Construction Reserve Funds	$ 0		0
Marketable Security Positions Held By The Company As Of September 30, 2017 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable security gains (losses), net			$ (12,800)	$ (53,000)

Fair Value Measurements (Estima

Fair Value Measurements (Estimated Fair Value Of Other Financial Assets And Liabilities) (Details)	Sep. 30, 2017USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash, cash equivalents and restricted cash	$ 269,592,000
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	2,773,000
Long-term debt, including current portion, Carrying Amount	739,552,000
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	269,592,000
Notes receivable from third parties (included in other receivables and other assets), Fair Value Disclosure	950,000
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	1,741,000
Debt Instrument, Fair Value Disclosure	749,775,000
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%
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%

Fair Value Measurements Fair 47

Fair Value Measurements Fair Value Measurements (Assets and Liabilities Measured on a Non-recurring Basis) (Details) $ in Thousands	Sep. 30, 2017USD ($)
Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Method Investments, Fair Value Disclosure	$ 0
Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Method Investments, Fair Value Disclosure	6,000
Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Method Investments, Fair Value Disclosure	$ 0

Stock Repurchases (Details)

Stock Repurchases (Details) $ in Millions	9 Months Ended
	Sep. 30, 2017USD ($)shares
Stock Repurchase Program, Remaining Authorized Repurchase Amount	$ 77.4
Restricted Stock [Member]
Treasury Stock, Shares, Acquired | shares	110,298
Treasury Stock, Value, Acquired, Cost Method	$ 7.6

Noncontrolling Interests in S49

Noncontrolling Interests in Subsidiaries (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Noncontrolling Interests in Subsidiaries [Line Items]
Noncontrolling interests in subsidiaries	$ 123,455		$ 123,455		$ 135,376
Net Income (Loss)	21,104	$ (34,026)	2,675	$ (105,483)
Net Income (Loss) Attributable to Noncontrolling Interest	3,543	$ 5,777	13,839	16,665
Inland River Services [Member] | Other Inland River Services Noncontrolling Interests [Member]
Noncontrolling Interests in Subsidiaries [Line Items]
Noncontrolling interests in subsidiaries	$ 959		$ 959		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	$ 122,344		$ 122,344		106,054
Assets, Net	249,700		249,700
Net Income (Loss)			33,200	32,400
Net Income (Loss) Attributable to Noncontrolling Interest			16,300	$ 15,900
Discontinued Operations [Member]
Noncontrolling Interests in Subsidiaries [Line Items]
Noncontrolling interests in subsidiaries	0		0		28,190
Other Segments [Member] | Other Noncontrolling Interests [Member]
Noncontrolling Interests in Subsidiaries [Line Items]
Noncontrolling interests in subsidiaries	$ 152		$ 152		$ 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] | Discontinued Operations [Member]
Noncontrolling Interests in Subsidiaries [Line Items]
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners	1.80%		1.80%
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 and Defined Ben50

Multiemployer and Defined Benefit 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

Multiemployer and Defined Ben51

Multiemployer and Defined Benefit Pension Plans Defined Benefit Pension Plan (Details) - USD ($)	3 Months Ended
	Sep. 30, 2017	Jul. 03, 2017
Compensation and Retirement Disclosure [Abstract]
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate		4.00%
Defined Benefit Plan, Fair Value of Plan Assets		$ 37,464,000
Defined Benefit Plan, Benefit Obligation		(37,227,000)
Defined Benefit Plan, Funded Status of Plan	$ 1,069,000	$ 237,000
Defined Benefit Plan, Net Periodic Benefit Cost	832,000
Defined Benefit Plan, Expected Future Benefit Payments, Remainder of Fiscal Year	909
Defined Benefit Plan, Expected Future Benefit Payments, Year Two	1,711
Defined Benefit Plan, Expected Future Benefit Payments, Year Three	1,804
Defined Benefit Plan, Expected Future Benefit Payments, Year Four	1,885
Defined Benefit Plan, Expected Future Benefit Payments, Year Five	$ 1,982
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Rate of Compensation Increase		4.50%
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Consumer Price Index		3.00%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Return on Assets	6.75%

Share Based Compensation (Share

Share Based Compensation (Share Based Compensation Plans) (Details)	9 Months Ended
	Sep. 30, 2017shares
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Director stock awards granted	1,250,000
Employee Stock Purchase Plan shares issued	36,552,000
Restricted stock awards granted	146,850,000
Restricted stock awards forfeited	2,177,000
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	970,069,000
Stock Option, Exercised	(386,417,000)
Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures in Period	3,374,000
Stock Option, Expired	(541,783,000)
Stock Options, Outstanding as of September 30, 2017	1,678,360,000
Shares available for future grants and ESPP purchases as of September 30, 2017	946,572,000
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	Dec. 31, 2017USD ($)	Sep. 30, 2017USD ($)equipment
Loss Contingencies [Line Items]
Unrecorded Unconditional Purchase Obligation, Due in Remainder of Fiscal Year						$ 6,266
Unrecorded Unconditional Purchase Obligation, Due in Second Years						3,389
Unrecorded Unconditional Purchase Obligation, Due in Third Year						529
Unrecorded Unconditional Purchase Obligation						$ 10,184
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 Harbor Tugs [Member]
Loss Contingencies [Line Items]
Unrecorded Unconditional Purchase Obligation, Maximum Quantity | equipment						2
Short-sea Container/RORO Vessels [Member]
Loss Contingencies [Line Items]
Unrecorded Unconditional Purchase Obligation, Maximum Quantity | equipment						1
Shipping Services [Member]
Loss Contingencies [Line Items]
Unrecorded Unconditional Purchase Obligation, Due in Remainder of Fiscal Year						$ 4,689
Unrecorded Unconditional Purchase Obligation, Due in Second Years						2,252
Unrecorded Unconditional Purchase Obligation, Due in Third Year						0
Unrecorded Unconditional Purchase Obligation						6,941
Inland River Services [Member]
Loss Contingencies [Line Items]
Unrecorded Unconditional Purchase Obligation, Due in Remainder of Fiscal Year						1,577
Unrecorded Unconditional Purchase Obligation, Due in Second Years						1,137
Unrecorded Unconditional Purchase Obligation, Due in Third Year						529
Unrecorded Unconditional Purchase Obligation						$ 3,243
Subsequent Event [Member]
Loss Contingencies [Line Items]
Unrecorded Unconditional Purchase Obligation					$ 2,600

Segment Information (Operating

Segment Information (Operating Results, Capital Expenditures And Assets By Reportable Segments) (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Segment Reporting Information [Line Items]
Operating Revenues	$ 158,171,000	$ 109,570,000	$ 392,376,000	$ 314,269,000
Costs and Expenses [Abstract]
Administrative and general	20,531,000	20,931,000	68,949,000	64,968,000
Depreciation and amortization	20,501,000	15,864,000	54,689,000	46,005,000
Total costs and expenses	148,290,000	103,368,000	375,794,000	304,609,000
Gains (Losses) on Asset Dispositions and Impairments, Net	5,209,000	(593,000)	10,918,000	2,590,000
Operating Income (Loss)	15,090,000	5,609,000	27,500,000	12,250,000
Other Income and Expenses [Abstract]
Derivative gains (losses), net	0	(862,000)	19,727,000	(3,527,000)
Foreign currency gains (losses), net	969,000	418,000	898,000	2,812,000
Other, net	64,000	(5,461,000)	68,000	(13,110,000)
Equity in Earnings (Losses) of 50% or Less Owned Companies, Net of Tax	488,000	(1,112,000)	2,929,000	(7,169,000)
Loss Before Taxes and Equity Earnings	(3,106,000)	(14,686,000)	10,333,000	(65,426,000)
Capital Expenditures			99,306,000	207,825,000
Property, Plant and Equipment, Gross	1,483,434,000		1,483,434,000		$ 1,178,556,000
Accumulated depreciation	487,049,000		487,049,000		444,559,000
Construction in progress	22,769,000		22,769,000		246,010,000
Net property and equipment	1,019,154,000		1,019,154,000		980,007,000
Inventories	3,952,000		3,952,000		2,582,000
Goodwill	32,773,000		32,773,000		32,758,000
Intangible Assets, Net	30,655,000		30,655,000		20,078,000
Disposal Group, Including Discontinued Operation, Assets		1,164,887,000		1,164,887,000
Total assets	1,782,965,000	2,954,133,000	1,782,965,000	2,954,133,000	$ 2,862,321,000
Inland River Services [Member]
Segment Reporting Information [Line Items]
Operating Revenues	44,608,000	41,094,000	124,921,000	114,522,000
Shipping Services [Member]
Segment Reporting Information [Line Items]
Operating Revenues	103,780,000	57,350,000	243,442,000	170,025,000
Witt O'Brien's LLC [Member]
Segment Reporting Information [Line Items]
Operating Revenues	9,667,000	11,010,000	23,665,000	29,356,000
Other Segments [Member]
Segment Reporting Information [Line Items]
Operating Revenues	116,000	116,000	348,000	366,000
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	158,171,000	109,570,000	392,376,000	314,269,000
Costs and Expenses [Abstract]
Operating Expenses	107,258,000	66,573,000	252,156,000	193,636,000
Administrative and general	20,531,000	20,931,000	68,949,000	64,968,000
Depreciation and amortization	20,501,000	15,864,000	54,689,000	46,005,000
Total costs and expenses	148,290,000	103,368,000	375,794,000	304,609,000
Gains (Losses) on Asset Dispositions and Impairments, Net	5,209,000	(593,000)	10,918,000	2,590,000
Operating Income (Loss)	15,090,000	5,609,000	27,500,000	12,250,000
Other Income and Expenses [Abstract]
Derivative gains (losses), net		(862,000)	19,727,000	(3,527,000)
Foreign currency gains (losses), net	969,000	418,000	898,000	2,812,000
Other, net	64,000	(5,461,000)	68,000	(13,110,000)
Equity in Earnings (Losses) of 50% or Less Owned Companies, Net of Tax	488,000	(1,112,000)	2,929,000	(7,169,000)
Capital Expenditures			99,306,000	207,825,000
Property, Plant and Equipment, Gross	1,483,434,000	1,018,370,000	1,483,434,000	1,018,370,000
Accumulated depreciation	487,049,000	434,049,000	487,049,000	434,049,000
Property, Plant and Equipment, Net In Service	996,385,000	584,321,000	996,385,000	584,321,000
Construction in progress	22,769,000	337,449,000	22,769,000	337,449,000
Net property and equipment	1,019,154,000	921,770,000	1,019,154,000	921,770,000
Investments, at Equity, and Advances to 50% or Less Owned Companies	175,387,000	198,052,000	175,387,000	198,052,000
Inventories	3,952,000	3,222,000	3,952,000	3,222,000
Goodwill	32,773,000	52,403,000	32,773,000	52,403,000
Intangible Assets, Net	30,655,000	23,496,000	30,655,000	23,496,000
Other Current And Long-Term Assets, Excluding Cash And Near Cash Assets	137,000,000	116,310,000	137,000,000	116,310,000
Operating Segments [Member] | Inland River Services [Member]
Segment Reporting Information [Line Items]
Operating Revenues	44,608,000	41,094,000	124,921,000	114,522,000
Costs and Expenses [Abstract]
Operating Expenses	35,388,000	31,496,000	99,859,000	89,060,000
Administrative and general	3,141,000	3,982,000	11,658,000	11,671,000
Depreciation and amortization	6,329,000	6,308,000	19,404,000	19,699,000
Total costs and expenses	44,858,000	41,786,000	130,921,000	120,430,000
Gains (Losses) on Asset Dispositions and Impairments, Net	5,136,000	(597,000)	11,260,000	2,588,000
Operating Income (Loss)	4,886,000	(1,289,000)	5,260,000	(3,320,000)
Other Income and Expenses [Abstract]
Derivative gains (losses), net		0	0	0
Foreign currency gains (losses), net	992,000	410,000	730,000	2,865,000
Other, net	0	(1,000)	0	(5,000)
Equity in Earnings (Losses) of 50% or Less Owned Companies, Net of Tax	(1,235,000)	(171,000)	(4,877,000)	(4,626,000)
Segment Profit (Loss)	4,643,000	(1,051,000)	1,113,000	(5,086,000)
Capital Expenditures			32,901,000	17,629,000
Property, Plant and Equipment, Gross	444,582,000	392,698,000	444,582,000	392,698,000
Accumulated depreciation	175,669,000	161,023,000	175,669,000	161,023,000
Property, Plant and Equipment, Net In Service	268,913,000	231,675,000	268,913,000	231,675,000
Construction in progress	2,177,000	9,948,000	2,177,000	9,948,000
Net property and equipment	271,090,000	241,623,000	271,090,000	241,623,000
Investments, at Equity, and Advances to 50% or Less Owned Companies	65,738,000	80,004,000	65,738,000	80,004,000
Inventories	1,866,000	2,033,000	1,866,000	2,033,000
Goodwill	2,415,000	2,427,000	2,415,000	2,427,000
Intangible Assets, Net	10,860,000	5,295,000	10,860,000	5,295,000
Other Current And Long-Term Assets, Excluding Cash And Near Cash Assets	54,295,000	55,710,000	54,295,000	55,710,000
Total assets	406,264,000	387,092,000	406,264,000	387,092,000
Operating Segments [Member] | Shipping Services [Member]
Segment Reporting Information [Line Items]
Operating Revenues	103,780,000	57,350,000	243,442,000	170,025,000
Costs and Expenses [Abstract]
Operating Expenses	65,866,000	28,542,000	137,070,000	86,045,000
Administrative and general	9,612,000	6,675,000	24,728,000	20,930,000
Depreciation and amortization	13,516,000	8,216,000	32,792,000	22,193,000
Total costs and expenses	88,994,000	43,433,000	194,590,000	129,168,000
Gains (Losses) on Asset Dispositions and Impairments, Net	73,000	3,000	(342,000)	3,000
Operating Income (Loss)	14,859,000	13,920,000	48,510,000	40,860,000
Other Income and Expenses [Abstract]
Derivative gains (losses), net		0	0	0
Foreign currency gains (losses), net	5,000	(3,000)	8,000	(12,000)
Other, net	59,000	(5,534,000)	118,000	(6,461,000)
Equity in Earnings (Losses) of 50% or Less Owned Companies, Net of Tax	1,493,000	(551,000)	8,150,000	(2,116,000)
Segment Profit (Loss)	16,416,000	7,832,000	56,786,000	32,271,000
Capital Expenditures			66,137,000	189,988,000
Property, Plant and Equipment, Gross	1,008,093,000	592,132,000	1,008,093,000	592,132,000
Accumulated depreciation	290,400,000	253,116,000	290,400,000	253,116,000
Property, Plant and Equipment, Net In Service	717,693,000	339,016,000	717,693,000	339,016,000
Construction in progress	20,592,000	328,692,000	20,592,000	328,692,000
Net property and equipment	738,285,000	667,708,000	738,285,000	667,708,000
Investments, at Equity, and Advances to 50% or Less Owned Companies	53,388,000	57,366,000	53,388,000	57,366,000
Inventories	2,032,000	952,000	2,032,000	952,000
Goodwill	1,852,000	1,852,000	1,852,000	1,852,000
Intangible Assets, Net	12,285,000	0	12,285,000	0
Other Current And Long-Term Assets, Excluding Cash And Near Cash Assets	44,845,000	27,508,000	44,845,000	27,508,000
Total assets	852,687,000	755,386,000	852,687,000	755,386,000
Operating Segments [Member] | Witt O'Brien's LLC [Member]
Segment Reporting Information [Line Items]
Operating Revenues	9,681,000	11,030,000	23,750,000	29,460,000
Costs and Expenses [Abstract]
Operating Expenses	6,068,000	6,618,000	15,483,000	18,850,000
Administrative and general	2,960,000	3,423,000	8,641,000	10,871,000
Depreciation and amortization	206,000	432,000	613,000	1,335,000
Total costs and expenses	9,234,000	10,473,000	24,737,000	31,056,000
Gains (Losses) on Asset Dispositions and Impairments, Net	0	1,000	0	(1,000)
Operating Income (Loss)	447,000	558,000	(987,000)	(1,597,000)
Other Income and Expenses [Abstract]
Derivative gains (losses), net		0	0	0
Foreign currency gains (losses), net	29,000	(24,000)	62,000	(124,000)
Other, net	0	0	0	0
Equity in Earnings (Losses) of 50% or Less Owned Companies, Net of Tax	100,000	91,000	237,000	277,000
Segment Profit (Loss)	576,000	625,000	(688,000)	(1,444,000)
Capital Expenditures			60,000	0
Property, Plant and Equipment, Gross	1,227,000	2,829,000	1,227,000	2,829,000
Accumulated depreciation	915,000	2,483,000	915,000	2,483,000
Property, Plant and Equipment, Net In Service	312,000	346,000	312,000	346,000
Construction in progress	0	0	0	0
Net property and equipment	312,000	346,000	312,000	346,000
Investments, at Equity, and Advances to 50% or Less Owned Companies	782,000	551,000	782,000	551,000
Inventories	54,000	237,000	54,000	237,000
Goodwill	28,506,000	48,124,000	28,506,000	48,124,000
Intangible Assets, Net	7,510,000	18,201,000	7,510,000	18,201,000
Other Current And Long-Term Assets, Excluding Cash And Near Cash Assets	13,802,000	13,186,000	13,802,000	13,186,000
Total assets	50,966,000	80,645,000	50,966,000	80,645,000
Operating Segments [Member] | Other Segments [Member]
Segment Reporting Information [Line Items]
Operating Revenues	116,000	116,000	348,000	366,000
Costs and Expenses [Abstract]
Operating Expenses	0	0	0	0
Administrative and general	180,000	410,000	559,000	834,000
Depreciation and amortization	0	0	0	0
Total costs and expenses	180,000	410,000	559,000	834,000
Gains (Losses) on Asset Dispositions and Impairments, Net	0	0	0	0
Operating Income (Loss)	(64,000)	(294,000)	(211,000)	(468,000)
Other Income and Expenses [Abstract]
Derivative gains (losses), net		0	0	0
Foreign currency gains (losses), net	(12,000)	(1,000)	(12,000)	(1,000)
Other, net	0	0	(300,000)	(6,723,000)
Equity in Earnings (Losses) of 50% or Less Owned Companies, Net of Tax	130,000	(481,000)	(581,000)	(704,000)
Segment Profit (Loss)	54,000	(776,000)	(1,104,000)	(7,896,000)
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	55,479,000	60,131,000	55,479,000	60,131,000
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	1,807,000	15,522,000	1,807,000	15,522,000
Total assets	57,286,000	75,653,000	57,286,000	75,653,000
Operating Segments [Member] | Corporate And Eliminations [Member]
Segment Reporting Information [Line Items]
Operating Revenues	(14,000)	(20,000)	(85,000)	(104,000)
Costs and Expenses [Abstract]
Operating Expenses	(64,000)	(83,000)	(256,000)	(319,000)
Administrative and general	4,638,000	6,441,000	23,363,000	20,662,000
Depreciation and amortization	450,000	908,000	1,880,000	2,778,000
Total costs and expenses	5,024,000	7,266,000	24,987,000	23,121,000
Gains (Losses) on Asset Dispositions and Impairments, Net	0	0	0	0
Operating Income (Loss)	(5,038,000)	(7,286,000)	(25,072,000)	(23,225,000)
Other Income and Expenses [Abstract]
Derivative gains (losses), net		(862,000)	19,727,000	(3,527,000)
Foreign currency gains (losses), net	(45,000)	36,000	110,000	84,000
Other, net	5,000	74,000	250,000	79,000
Equity in Earnings (Losses) of 50% or Less Owned Companies, Net of Tax	0	0	0	0
Capital Expenditures			208,000	208,000
Property, Plant and Equipment, Gross	29,532,000	30,711,000	29,532,000	30,711,000
Accumulated depreciation	20,065,000	17,427,000	20,065,000	17,427,000
Property, Plant and Equipment, Net In Service	9,467,000	13,284,000	9,467,000	13,284,000
Construction in progress	0	(1,191,000)	0	(1,191,000)
Net property and equipment	9,467,000	12,093,000	9,467,000	12,093,000
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	22,251,000	4,384,000	22,251,000	4,384,000
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	(14,000)	(20,000)	(85,000)	104,000
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	14,000	20,000	85,000	(104,000)
Segment Reconciling Items [Member]
Other Income and Expenses [Abstract]
Other Income (Expense) not included in Segment Profit (Loss)	19,229,000	14,390,000	37,860,000	63,851,000
Less Equity Earnings included in Segment Profit (Loss)	(488,000)	1,112,000	(2,929,000)	7,169,000
Cash And Near Cash Assets	$ 384,044,000	$ 473,993,000	$ 384,044,000	$ 473,993,000

Discontinued Operations (Detail

Discontinued Operations (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Costs and Expenses [Abstract]
Total costs and expenses	$ 148,290	$ 103,368	$ 375,794	$ 304,609
Gains (Losses) on Asset Dispositions and Impairments, Net	5,209	(593)	10,918	2,590
Net Income (Loss)	0	(25,392)	(23,150)	(62,809)
Offshore Marine Services [Member]
Operating Revenues	0	54,125	62,291	171,275
Costs and Expenses [Abstract]
Operating	0	41,159	65,888	134,254
Administrative and general	0	10,588	29,682	34,915
Depreciation and amortization	0	14,213	22,181	44,305
Total costs and expenses	0	65,960	117,751	213,474
Operating Income (Loss)	0	(41,068)	(51,241)	(92,169)
Other Income (Expense), Net	0	(2,993)	1,780	(14,675)
Income Tax Expense (Benefit)	0	(15,263)	(12,931)	(35,831)
Equity in Earnings (Losses) of 50% or Less Owned Companies	0	790	1,663	(364)
Net Income (Loss)	0	(28,008)	(34,867)	(71,377)
Net Income (Loss) Attributable to Noncontrolling Interests	0	(73)	(1,892)	(904)
Illinois Corn Processing LLC [Member]
Operating Revenues	0	44,019	78,061	134,204
Costs and Expenses [Abstract]
Operating	0	39,879	76,306	122,321
Administrative and general	0	750	2,109	2,318
Depreciation and amortization	0	1,055	2,354	3,172
Total costs and expenses	0	41,684	80,769	127,811
Operating Income (Loss)	0	2,335	(2,708)	6,393
Other Income (Expense), Net	18,223	537	20,558	3,014
Income Tax Expense (Benefit)	7,296	921	7,363	2,903
Net Income (Loss)	10,927	1,951	10,487	6,504
Net Income (Loss) Attributable to Noncontrolling Interests	0	569	(539)	1,975
Intersegment Eliminations [Member]
Operating Revenues	0	(731)	(1,176)	(1,799)
Costs and Expenses [Abstract]
Operating	0	(815)	(1,289)	(2,065)
Administrative and general	0	(24)	(42)	(77)
Total costs and expenses	0	(839)	(1,331)	(2,142)
Operating Income (Loss)	0	108	155	343
Other Income (Expense), Net	0	916	1,738	2,833
Income Tax Expense (Benefit)	0	359	663	1,112
Net Income (Loss)	0	665	1,230	2,064
Offshore Marine Services [Member] | Offshore Marine Services [Member]
Costs and Expenses [Abstract]
Gains (Losses) on Asset Dispositions and Impairments, Net	$ 0	$ (29,233)	$ 4,219	$ (49,970)