Long-term Debt (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Long-term Debt
Debt and Capital Lease Obligations, Total	$ 1,289,165	$ 1,267,637
Less current maturities of long-term debt	(44,015)	(30,853)
Less discount on senior secured credit facility Term Loan B	(972)	(1,056)
Less debt issuance costs, net of accumulated amortization of $9.7 million and $6.8 million, respectively	(22,228)	(25,151)
Long-term debt, net of current maturities and debt issuance costs	1,221,950	1,210,577
Debt issuance costs, accumulated amortization (in dollars)	9,700	6,800
Other assets	79,358	87,318
Early adoption adjustments for new accounting principle | Accounting Standards Update 2015-03
Long-term Debt
Other assets	(22,200)	(25,200)
Long-term debt	(22,200)	(25,200)
Senior Secured Credit Facility
Long-term Debt
Debt and Capital Lease Obligations, Total	813,750	807,500
Senior unsecured notes 5.875% due November 2021
Long-term Debt
Debt and Capital Lease Obligations, Total	$ 300,000	300,000
Debt instrument interest rate stated percentage	5.875%
Principal amount	$ 300,000
Other long term obligations
Long-term Debt
Debt and Capital Lease Obligations, Total	150,300	135,000
Capital Lease Obligations.
Long-term Debt
Debt and Capital Lease Obligations, Total	$ 25,115	$ 25,137