Long-Term Debt and Finance Leases - Summary (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Jul. 07, 2017	May 31, 2017
Long-Term Debt and Capital Leases
Available borrowing capacity	$ 239,500
Long-term debt	2,275,300	$ 2,300,900
Finance lease liability	23,100
Capital lease obligations		5,100
Total long-term debt and finance lease obligations	2,298,400	2,306,000
Debt issuance costs, net	(8,000)	(10,500)
Sub-total	2,290,400	2,295,500
Less current portion	(30,900)	(24,100)
Long-term portion	$ 2,259,500	2,271,400
Term B Loans
Long-Term Debt and Capital Leases
Effective interest rate (as a percent)	5.59%
Long-term debt	$ 2,220,300	2,240,900	$ 2,280
Debt issuance costs, net	(6,000)	(7,700)
Net discount	8,400	10,600
Revolving Credit Facility
Long-Term Debt and Capital Leases
Available borrowing capacity	$ 239,500
Effective interest rate (as a percent)	4.73%
Long-term debt	$ 55,000	60,000
Debt issuance costs, net	(2,000)	$ (2,800)
Sub-total	55,000
Maximum borrowing capacity	300,000			$ 200,000
Outstanding letters of credit	$ 5,500