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, 2015
Jun. 30, 2014
Derivative [Line Items]    
Derivative gains (losses), net $ (1,570) $ (143)
Options on equities and equity indices    
Derivative [Line Items]    
Derivative gains (losses), net (442) 22
Forward Currency Exchange, Option And Future Contracts [Member]    
Derivative [Line Items]    
Derivative gains (losses), net (302) 187
Interest rate swap agreements    
Derivative [Line Items]    
Derivative gains (losses), net (5) (135)
Commodity swap, option and future contracts, exchange traded    
Derivative [Line Items]    
Derivative gains (losses), net (2,271) 950
Commodity swap, option and future contracts, non-exchange traded    
Derivative [Line Items]    
Derivative gains (losses), net 1,450 $ (1,167)
Not Designated as Hedging Instrument [Member] | Forward Currency Exchange, Option And Future Contracts [Member]    
Derivative [Line Items]    
Derivative, Notional Amount $ 2,500  
Not Designated as Hedging Instrument [Member] | Interest rate swap agreements    
Derivative [Line Items]    
Derivative, Fixed Interest Rate 3.00%  
Derivative, Notional Amount $ 8,100  
Not Designated as Hedging Instrument [Member] | OSV Partners [Member] | Interest rate swap agreements    
Derivative [Line Items]    
Derivative, Lower Fixed Interest Rate Range 1.89%  
Derivative, Higher Fixed Interest Rate Range 2.27%  
Derivative, Notional Amount $ 45,600  
Not Designated as Hedging Instrument [Member] | Dynamic Offshore Drilling Ltd [Member] | Interest rate swap agreements    
Derivative [Line Items]    
Derivative, Fixed Interest Rate 1.30%  
Derivative, Notional Amount $ 88,500  
Not Designated as Hedging Instrument [Member] | Dorian LPG [Member] | Interest rate swap agreements    
Derivative [Line Items]    
Derivative, Lower Fixed Interest Rate Range 2.96%  
Derivative, Higher Fixed Interest Rate Range 5.40%  
Derivative, Notional Amount $ 116,500