Fair Value Measurements Fair Value Measurements (Non-financial Assets Measured on a Non-recurring Basis) (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Asset Impairment Charges	$ (51,700)	$ (6,900)
Provision for Loan and Lease Losses	6,700
Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Property and Equipment, Fair Value Disclosure	0
Intangible Assets, Net, Fair Value Disclosure	0
Investments at cost, Fair Value Disclosure	0
Notes Receivable, Fair Value Disclosure	0
Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Property and Equipment, Fair Value Disclosure	2,853
Intangible Assets, Net, Fair Value Disclosure	0
Investments at cost, Fair Value Disclosure	3,500
Notes Receivable, Fair Value Disclosure	0
Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Property and Equipment, Fair Value Disclosure	172,230
Intangible Assets, Net, Fair Value Disclosure	0
Investments at cost, Fair Value Disclosure	0
Notes Receivable, Fair Value Disclosure	0
Other Offshore Marine Services Joint Ventures [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Asset Impairment Charges	(300)
Other Offshore Marine Services Joint Ventures [Member] | 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
Other Offshore Marine Services Joint Ventures [Member] | 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	0
Other Offshore Marine Services Joint Ventures [Member] | 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
Cost-method Investments [Member] | Shipping Services Joint Ventures [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Asset Impairment Charges	$ (6,500)