Derivative Instruments and Hedging Activities (Details 2) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Fair value of derivative instruments
Asset Derivative	$ 118,305	$ 174,803
Liability Derivative	55,331	126,242
Designated as hedging instruments | Foreign currency forward contracts | Other current assets
Fair value of derivative instruments
Asset Derivative	36,811	68,889
Liability Derivative	16,331	32,430
Designated as hedging instruments | Foreign currency forward contracts | Other current liabilities
Fair value of derivative instruments
Asset Derivative	606	129
Liability Derivative	1,663	3,940
Designated as hedging instruments | Foreign currency forward contracts | Other non-current assets
Fair value of derivative instruments
Asset Derivative	5,837
Liability Derivative	2,757
Designated as hedging instruments | Foreign currency forward contracts | Other non-current liabilities
Fair value of derivative instruments
Asset Derivative	83
Liability Derivative	2,934	24,832
Not designated as hedging instruments | Foreign currency forward contracts | Other current assets
Fair value of derivative instruments
Asset Derivative	55,574	66,639
Liability Derivative	8,411	10,395
Not designated as hedging instruments | Foreign currency forward contracts | Other current liabilities
Fair value of derivative instruments
Asset Derivative	349	2,462
Liability Derivative	7,478	22,289
Not designated as hedging instruments | Foreign currency forward contracts | Other non-current assets
Fair value of derivative instruments
Asset Derivative	19,045	36,684
Liability Derivative	$ 15,757	$ 32,356