Long-Term Debt and Finance Leases - Summary (Details) - USD ($) $ in Millions	Jun. 30, 2024	Dec. 31, 2023	Dec. 20, 2021
Long-Term Debt and Capital Leases
Available borrowing capacity	$ 0.4
Long-term debt	953.0	$ 912.3
Other Financing	1.2	1.4
Finance lease obligations	$ 23.6	$ 24.6
Finance Lease, Liability, Statement of Financial Position	Long-term portion, Less current portion	Long-term portion, Less current portion
Total long-term debt, finance lease obligations and other	$ 977.8	$ 938.3
Debt issuance costs, net	(3.3)	(3.8)
Sub-total	974.5	934.5
Less current portion	(17.9)	(18.8)
Long-term portion	$ 956.6	915.7
Term B Loans
Long-Term Debt and Capital Leases
Effective interest rate (as a percent)	8.33%
Long-term debt	$ 708.0	711.3
Debt issuance costs, net	(2.6)	(3.0)
Net discount	3.7	4.1
Revolving Credit Facility
Long-Term Debt and Capital Leases
Available borrowing capacity	$ 0.4
Effective interest rate (as a percent)	8.08%
Long-term debt	$ 245.0	201.0
Debt issuance costs, net	(0.7)	$ (0.8)
Maximum borrowing capacity	250.0		$ 250.0
Outstanding letters of credit	$ 4.6