Long-term Debt (Details) (USD $)	6 Months Ended	12 Months Ended
	Jun. 30, 2013	Dec. 31, 2012
Long-term debt
Total long- term debt	$ 811,935,000	$ 762,368,000
Less current portion	(12,907,000)	(11,065,000)
Long- term debt, non-current	799,028,000	751,303,000
Revolving credit facility due through October 2016
Long-term debt
Face amount	140,000,000	140,000,000
Credit facility interest rate basis	LIBOR
Total long- term debt	50,000,000	7,500,000
8 7/8% Senior Secured Second Lien Notes due January 15, 2017
Long-term debt
Face amount	350,000,000	350,000,000
Total long- term debt	348,752,000	348,577,000
Fixed interest rate (as a percent)	8.875%	8.875%
9 7/8% Senior Subordinated Notes due April 15, 2017
Long-term debt
Face amount	376,300,000	376,300,000
Total long- term debt	374,667,000	374,461,000
Fixed interest rate (as a percent)	9.875%	9.875%
Other notes payable due through August 2019
Long-term debt
Total long- term debt	4,044,000	3,753,000
Average interest rate (as a percent)	15.70%	15.70%
Seller financing promissory notes due through December 2013
Long-term debt
Total long- term debt	1,031,000	2,093,000
Average interest rate (as a percent)	6.21%	6.21%
Seller financing promissory notes with average interest rate of 6.0% due through May 2018
Long-term debt
Total long- term debt	2,107,000
Average interest rate (as a percent)	6.00%
Capital leases payable
Long-term debt
Total long- term debt	$ 31,334,000	$ 25,984,000
Interest rate, minimum (as a percent)	1.00%	1.00%
Interest rate, maximum (as a percent)	8.50%	8.50%