Long-Term Debt and Finance Leases - Term B Loans and Revolving Credit Facility (Details) - USD ($) $ in Thousands				1 Months Ended	12 Months Ended
	Jul. 17, 2017	Jul. 07, 2017	Mar. 20, 2017	May 31, 2017	Dec. 31, 2017	Dec. 31, 2019	Dec. 31, 2018
Long-Term Debt and Capital Leases
Long-term debt						$ 2,275,300	$ 2,300,900
Loss on early extinguishment of debt					$ 32,100
Term B Loans
Long-Term Debt and Capital Leases
Debt issued		$ 230,500
Long-term debt		2,280				2,220,300	2,240,900
Loss on early extinguishment of debt		$ 6,300
Term B Loans | Alternate base rate
Long-Term Debt and Capital Leases
Basis spread on variable rate (as a percent)		2.25%
Term B Loans | Adjusted LIBOR rate
Long-Term Debt and Capital Leases
Basis spread on variable rate (as a percent)		3.25%
Revolving Credit Facility
Long-Term Debt and Capital Leases
Long-term debt						55,000	$ 60,000
Additional borrowing capacity		$ 100,000
Borrowings available				$ 200,000		$ 300,000
Borrowing capacity upon compliance with conditions		$ 300,000		300,000
Loss on early extinguishment of debt				$ 1,000
Revolving Credit Facility | Alternate base rate
Long-Term Debt and Capital Leases
Basis spread on variable rate (as a percent)		2.00%		2.00%
Revolving Credit Facility | Adjusted LIBOR rate
Long-Term Debt and Capital Leases
Basis spread on variable rate (as a percent)		3.00%		3.00%
10.25 % Senior Notes
Long-Term Debt and Capital Leases
Loss on early extinguishment of debt	$ 19,800		$ 5,000
Interest rate (as a percent)			10.25%
Repayments of long-term debt	$ 729,900		$ 95,100