Nature Of Operations And Accounting Policies (Narrative) (Details)	12 Months Ended
Dec. 31, 2016 USD ($) equipment shares	Dec. 31, 2015 USD ($) equipment	Dec. 31, 2014 USD ($) equipment
Nature of Operations and Accounting Policies [Line Items]
Inventory write-down	$ 2,700,000	$ 3,000,000	$ 400,000
Depreciation	122,500,000	122,900,000	127,600,000
Capitalized interest	18,500,000	18,500,000	17,000,000
Amortization expense	2,477,000	3,100,000	4,300,000
Asset Impairment Charges	(130,800,000)	(7,100,000)	(4,400,000)
Equity Method Investment, Other than Temporary Impairment	14,700,000		$ 3,300,000
Investment Owned, at Cost	$ 4,432,000	$ 16,045,000
Offshore Marine Services [Member]
Nature of Operations and Accounting Policies [Line Items]
Percentage of Operating Revenues	26.00%	35.00%	40.00%
Asset Impairment Charges	$ (119,700,000)
Goodwill, Impairment Loss		$ 13,400,000
Inland River Services [Member]
Nature of Operations and Accounting Policies [Line Items]
Percentage of Operating Revenues	20.00%	22.00%	19.00%
Shipping Services [Member]
Nature of Operations and Accounting Policies [Line Items]
Percentage of Operating Revenues	28.00%	21.00%	16.00%
Illinois Corn Processing Llc [Member]
Nature of Operations and Accounting Policies [Line Items]
Percentage of Operating Revenues	21.00%	16.00%	18.00%
Witt O'Brien's LLC [Member]
Nature of Operations and Accounting Policies [Line Items]
Percentage of Operating Revenues	5.00%	5.00%	2.00%
Goodwill, Impairment Loss	$ 19,600,000
Dorian LPG [Member]
Nature of Operations and Accounting Policies [Line Items]
Investment Owned, Balance, Shares \| shares	9,177,135
Investment Owned, at Fair Value	$ 8.21	$ 11.77
Investment Owned, at Cost	$ 13.66
Offshore Support Vessels Anchor Handling Towing Supply [Member]
Nature of Operations and Accounting Policies [Line Items]
Number of Equipments Removed from Service \| equipment	0	0	1
Offshore Support Vessels Anchor Handling Towing Supply [Member] \| Offshore Marine Services [Member]
Nature of Operations and Accounting Policies [Line Items]
Asset Impairment Charges	$ (62,800,000)
Property, Plant and Equipment, Useful Life	4 years
Liftboats [Member]
Nature of Operations and Accounting Policies [Line Items]
Number of Equipments Removed from Service \| equipment	0	0	1
Liftboats [Member] \| Offshore Marine Services [Member]
Nature of Operations and Accounting Policies [Line Items]
Asset Impairment Charges	$ (19,900,000)
Property, Plant and Equipment, Useful Life	6 years
Offshore Support Vessels Specialty [Member] \| Offshore Marine Services [Member]
Nature of Operations and Accounting Policies [Line Items]
Asset Impairment Charges	$ (12,700,000)
Property, Plant and Equipment, Useful Life	6 years
Offshore Support Vessels [Member]
Nature of Operations and Accounting Policies [Line Items]
Asset Impairment Charges	$ (120,800,000)	$ (6,600,000)
Number of Equipments Removed from Service \| equipment	9	2	14
Offshore Support Vessels [Member] \| Offshore Marine Services [Member]
Nature of Operations and Accounting Policies [Line Items]
Asset Impairment Charges	$ (3,600,000)
Disposal Group, Held-for-sale, Not Discontinued Operations [Member] \| Offshore Support Vessels [Member] \| Offshore Marine Services [Member]
Nature of Operations and Accounting Policies [Line Items]
Asset Impairment Charges	$ (20,700,000)

Nature of operations and accounting policies.

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Number of equipments removed from service.

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Percentage of operating revenues.

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The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

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Amount of write-down of assets recognized in the income statement. Includes, but is not limited to, losses from tangible assets, intangible assets and goodwill.

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The amount of expense recognized in the current period that reflects the allocation of the cost of tangible assets over the assets' useful lives. Includes production and non-production related depreciation.

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This item represents an other than temporary decline in value that has been recognized against an investment accounted for under the equity method of accounting. The excess of the carrying amount over the fair value of the investment represents the amount of the write down which is or was reflected in earnings. The written down value is a new cost basis with the adjusted value of the investment becoming its new carrying value subject to the equity accounting method. Evidence of a loss in value might include, but would not necessarily be limited to, absence of an ability to recover the carrying amount of the investment or inability of the investee to sustain an earnings capacity which would justify the carrying amount of the investment.

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Period the instrument, asset or liability is expected to be outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Amount of loss from the write-down of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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Amount of interest capitalized, including amount of allowance for funds used during construction.

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Charge to cost of goods sold that represents the reduction of the carrying amount of inventory, generally attributable to obsolescence or market conditions.

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Cost of the investment.

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Value of the investment at close of period. For schedules of investments that are categorized, the value would be aggregated by category. For investment in and advances to affiliates, if operations of any controlled companies are different in character from those of the company, group such affiliates within divisions and by type of activities.

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Balance held at close of period in number of shares.

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