Long-Term Debt and Finance Leases - Summary (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Long-Term Debt and Capital Leases
Available borrowing capacity	$ 256.6
Long-term debt	2,237.9	$ 2,275.3
Other Financing	0.8
Finance lease obligations	32.9	23.1
Total long-term debt, finance lease obligations and other	2,271.6	2,298.4
Debt issuance costs, net	(5.6)	(8.0)
Sub-total	2,266.0	2,290.4
Less current portion	(37.5)	(30.9)
Long-term portion	$ 2,228.5	2,259.5
Term B Loans
Long-Term Debt and Capital Leases
Effective interest rate (as a percent)	5.28%
Long-term debt	$ 2,199.9	2,220.3
Debt issuance costs, net	(4.4)	(6.0)
Net discount	6.1	8.4
Revolving Credit Facility
Long-Term Debt and Capital Leases
Available borrowing capacity	$ 256.6
Effective interest rate (as a percent)	3.15%
Long-term debt	$ 38.0	55.0
Debt issuance costs, net	(1.2)	$ (2.0)
Sub-total	38.0
Maximum borrowing capacity	300.0
Outstanding letters of credit	5.4
Revolving Credit Facility | Letters of credit
Long-Term Debt and Capital Leases
Maximum borrowing capacity	$ 40.0