Financial Instruments (Details 2) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010
Derivatives Designated as Hedging Instruments
Derivative contracts
Period over which gains and losses are reclassified to earnings, low end of range (in years)	10 years
Period over which gains and losses are reclassified to earnings, high end of range (in years)	15 years
Asset Derivatives	$ 44,910	$ 31,803
Liability Derivatives	1,792	3,860
Derivatives Designated as Hedging Instruments | Foreign currency forward exchange contracts
Derivative contracts
Asset Derivatives	274
Liability Derivatives		29
Derivatives Designated as Hedging Instruments | Cross-currency interest rate swaps
Derivative contracts
Asset Derivatives	44,636	31,803
Liability Derivatives	1,792	3,831
Derivatives Not Designated as Hedging Instruments | Foreign currency forward exchange contracts
Derivative contracts
Asset Derivatives	2,912	2,787
Liability Derivatives	$ 1,207	$ 1,042