Quarterly report pursuant to Section 13 or 15(d)

Derivative Financial Instruments (Schedule Of Contracts Designated As Hedged Instruments) (Details)

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Derivative Financial Instruments (Schedule Of Contracts Designated As Hedged Instruments) (Details) (USD $)
In Thousands, unless otherwise specified
9 Months Ended 12 Months Ended
Sep. 30, 2012
Dec. 31, 2011
Norwegian Kroners [Member]
   
Foreign Exchange Contracts [Line Items]    
Foreign exchange contracts, Notional Amount   $ 3,633
Derivative, Maturity Date   Sep. 01, 2012
British Pounds [Member]
   
Foreign Exchange Contracts [Line Items]    
Foreign exchange contracts, Notional Amount 1,157 1,632
Derivative, Maturity Date Aug. 01, 2013 Feb. 01, 2013
Euros [Member]
   
Foreign Exchange Contracts [Line Items]    
Foreign exchange contracts, Notional Amount 18,628 14,937
Derivative, Maturity Date Feb. 01, 2014 Feb. 01, 2013
Swiss Francs [Member]
   
Foreign Exchange Contracts [Line Items]    
Foreign exchange contracts, Notional Amount 23,988 24,225
Derivative, Maturity Date Feb. 01, 2014 Feb. 01, 2013
Canadian Dollars [Member]
   
Foreign Exchange Contracts [Line Items]    
Foreign exchange contracts, Notional Amount $ 9,007 $ 9,141
Derivative, Maturity Date Sep. 01, 2013 Mar. 01, 2013