Quarterly report pursuant to Section 13 or 15(d)

Fair Value Measurements Fair Value Measurements (Non-financial Assets Measured on a Non-recurring Basis) (Details)

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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)