Long-term Debt (Details) (USD $)	Jun. 30, 2014	Dec. 31, 2013
Long-term Debt
Debt	$ 1,056,939,000	$ 1,052,015,000
Less current maturities of long-term debt	(27,823,000)	(27,598,000)
Less discount on debt	(1,140,000)	(1,223,000)
Long-term debt, net of current maturities	1,027,976,000	1,023,194,000
Senior Secured Credit Facility [Member]
Long-term Debt
Debt	736,250,000	750,000,000
Senior Unsecured Notes5.875 Percent Due November2012 [Member]
Long-term Debt
Debt	300,000,000	300,000,000
Debt instrument interest rate stated percentage	5.875%
Principal amount	300,000,000
Other Long Term Obligation [Member]
Long-term Debt
Debt	18,500,000
Capital Lease Obligations [Member]
Long-term Debt
Debt	$ 2,189,000	$ 2,015,000