Long-term Debt - Debt Summary (Details) - USD ($)	Sep. 30, 2018	Dec. 31, 2017	Jan. 19, 2017
Long-term Debt
Long-term debt	$ 1,074,555,000	$ 1,280,201,000
Less current maturities of long-term debt	(39,223,000)	(35,612,000)
Less discount on senior secured credit facility Term Loan B	(1,418,000)	(2,558,000)
Less debt issuance costs	(20,167,000)	(27,406,000)
Long-term debt, net of current maturities and debt issuance costs	1,013,747,000	1,214,625,000
Senior Secured Credit Facility
Long-term Debt
Long-term debt	570,000,000	760,000,000
Senior Unsecured Notes 5.625 Percent Due January 15, 2027
Long-term Debt
Long-term debt	400,000,000	400,000,000
Principal amount	$ 400,000,000		$ 400,000,000
Interest rate (as a percent)	5.625%		5.625%
Other long-term obligations
Long-term Debt
Long-term debt	$ 104,525,000	119,310,000
Capital leases
Long-term Debt
Long-term debt	$ 30,000	$ 891,000

Sum of the carrying values as of the balance sheet date of all debt, including all short-term borrowings, long-term debt, and capital lease obligations.

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