Long-Term Obligations (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Debt Instrument [Line Items]
Senior Notes	$ 592,422,000	$ 573,984,000
Derivative, Cost of Hedge Net of Cash Received	0	0	382
Summary of long-term obligations
Secured seller notes	266,000	346,000
Total debt obligations	592,688,000	574,330,000
Capital lease obligations	37,955,000	44,523,000
Long term debt including capital lease obligation	630,643,000	618,853,000
Less - current portion	(39,002,000)	(32,571,000)
Long term debt and capital lease obligations	591,641,000	586,282,000
Line of Credit Facility, Amount Outstanding	$ 0	$ 0