Fair Value Measurements (Details) (Fair Value, Measurements, Recurring [Member], Interest rate swaps [Member], USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Balances of assets and liabilities measured at fair value on a recurring basis
Other long-term liabilities Interest rate swaps	$ (10,687)	$ (8,478)
Level 1 [Member]
Balances of assets and liabilities measured at fair value on a recurring basis
Other long-term liabilities Interest rate swaps
Level 2 [Member]
Balances of assets and liabilities measured at fair value on a recurring basis
Other long-term liabilities Interest rate swaps	(10,687)	(8,478)
Level 3 [Member]
Balances of assets and liabilities measured at fair value on a recurring basis
Other long-term liabilities Interest rate swaps