Financial Instruments (Details 5) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011
Cross-Currency Interest Rate Swaps Maturing 2018
Derivatives Designated as Hedging Instruments
Contractual Amount	$ 250,000
Cross-Currency Interest Rate Swaps Maturing 2020
Derivatives Designated as Hedging Instruments
Contractual Amount	220,000
Cross-Currency Interest Rate Swaps Maturing 2013
Derivatives Designated as Hedging Instruments
Contractual Amount	$ 1,800