Fair Value of Financial Instruments - Level 3 (Details) (Fair Value, Inputs, Level 3 [Member], USD $) In Thousands, unless otherwise specified			6 Months Ended
	Jun. 30, 2012	Dec. 31, 2011	Jun. 30, 2012 Change in estimate	Jun. 30, 2012 Accretion [Member]	Jun. 30, 2012 Fair Value, Measurements, Recurring [Member]	Dec. 31, 2011 Fair Value, Measurements, Recurring [Member]	Jun. 30, 2012 Other accrued liabilities [Member] Fair Value, Measurements, Recurring [Member]	Jun. 30, 2012 Other long-term liabilities [Member] Fair Value, Measurements, Recurring [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Obligations, Fair Value Disclosure					$ 6,556	$ 7,594	$ (600)	$ (6,000)
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at December 31, 2011	6,556	7,594
Fair value level 3 activity			(1,562)	524
Balance at June 30, 2012	$ 6,556	$ 7,594