Quarterly report pursuant to Section 13 or 15(d)

Derivative Instruments And Hedging Strategies (Recognized Gains (Losses) On Derivative Instruments Not Designated As Hedging Instruments) (Details)

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Derivative Instruments And Hedging Strategies (Recognized Gains (Losses) On Derivative Instruments Not Designated As Hedging Instruments) (Details) - USD ($)
$ in Thousands
6 Months Ended
Jun. 30, 2017
Jun. 30, 2016
Not Designated as Hedging Instrument [Member]    
Derivative [Line Items]    
Derivative gains (losses), net $ (302) $ 3,061
Not Designated as Hedging Instrument [Member] | Options On Equities And Equity Indices [Member]    
Derivative [Line Items]    
Derivative gains (losses), net 0 3,079
Not Designated as Hedging Instrument [Member] | Forward Currency Exchange, Option And Future Contracts [Member]    
Derivative [Line Items]    
Derivative gains (losses), net (56) 0
Not Designated as Hedging Instrument [Member] | Foreign currency exchange, option and future contracts    
Derivative [Line Items]    
Derivative, Notional Amount 100  
Not Designated as Hedging Instrument [Member] | Interest rate swap agreements    
Derivative [Line Items]    
Derivative gains (losses), net (391) (18)
Derivative, Notional Amount $ 59,400  
Fixed interest rate 2.06%  
Not Designated as Hedging Instrument [Member] | OSV Partners [Member] | Interest rate swap agreements    
Derivative [Line Items]    
Derivative, Notional Amount $ 35,500  
Not Designated as Hedging Instrument [Member] | Dynamic Offshore Drilling Ltd [Member] | Interest rate swap agreements    
Derivative [Line Items]    
Derivative, Notional Amount $ 69,100  
Fixed interest rate 1.30%  
Three Point Seven Five Percentage Convertible Notes [Member]    
Derivative [Line Items]    
Debt Instrument, Interest Rate, Stated Percentage 3.75%  
Three Point Seven Five Percentage Convertible Notes [Member] | Not Designated as Hedging Instrument [Member]    
Derivative [Line Items]    
Embedded Derivative, Loss on Embedded Derivative $ 145 $ 0
Minimum [Member] | Not Designated as Hedging Instrument [Member] | OSV Partners [Member] | Interest rate swap agreements    
Derivative [Line Items]    
Fixed interest rate 1.89%  
Maximum [Member] | Not Designated as Hedging Instrument [Member] | OSV Partners [Member] | Interest rate swap agreements    
Derivative [Line Items]    
Fixed interest rate 2.27%