Derivative Instruments - Designated as hedging, Financial Position (Details) (Designated as Hedging Instrument [Member], USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Derivatives, Fair Value [Line Items]
Asset Derivatives	$ 0	$ 0
Liability Derivatives	1,610	0
Interest Rate Swap [Member] | Accrued Liabilities [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives	0	0
Liability Derivatives	550	0
Interest Rate Swap [Member] | Other long-term liabilities [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives	0	0
Liability Derivatives	$ 1,060	$ 0