Investments, At Equity, And Advances To 50% Or Less Owned Companies (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Schedule Of Equity Method Investments [Line Items]
Equity in Earnings (Losses) of 50% or Less Owned Companies, Net of Tax	$ (7,162)	$ 1,064	$ (7,211)	$ 4,963
Asset Impairment Charges			21,300	$ 6,600
Guarantor Obligations, Maximum Exposure, Undiscounted	1,800		1,800
Allocable Share of Uncalled Capital	3,000		3,000
Falcon Global [Member]
Schedule Of Equity Method Investments [Line Items]
Partners' Capital Account, Contributions			6,000
Other Offshore Marine Services Joint Ventures [Member]
Schedule Of Equity Method Investments [Line Items]
Partners' Capital Account, Contributions			200
Asset Impairment Charges			300
Guarantor Obligations, Maximum Exposure, Undiscounted	82,600		82,600
SCFCo Holdings [Member]
Schedule Of Equity Method Investments [Line Items]
Partners' Capital Account, Contributions			800
Outstanding Working Capital Advances At End Of Period	26,900		26,900
Sea-Access [Member]
Schedule Of Equity Method Investments [Line Items]
Proceeds from Equity Method Investment, Dividends or Distributions, Return of Capital			2,000
Partners' Capital Account, Return of Capital			7,600
Seajon [Member]
Schedule Of Equity Method Investments [Line Items]
Proceeds from Equity Method Investment, Dividends or Distributions, Return of Capital			600
Avion Pacific Limited [Member]
Schedule Of Equity Method Investments [Line Items]
Outstanding Working Capital Advances At End Of Period	3,000		3,000
Payments for Advance to Affiliate			3,000
VA&E [Member]
Schedule Of Equity Method Investments [Line Items]
Outstanding Working Capital Advances At End Of Period	8,200		8,200
Line of Credit Facility, Maximum Borrowing Capacity	$ 6,000		6,000
Proceeds from Unsecured Lines of Credit			10,000
Repayments of Long-term Lines of Credit			(8,900)
Other Corporate Joint Ventures [Member]
Schedule Of Equity Method Investments [Line Items]
Payments for Advance to Affiliate			400
Offshore Support Vessels [Member] | Other Offshore Marine Services Joint Ventures [Member]
Schedule Of Equity Method Investments [Line Items]
Equity in Earnings (Losses) of 50% or Less Owned Companies, Net of Tax			$ 3,000