Leases - Aggregate lease maturities (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Finance Leases
First year	$ 11.1	$ 10.9
Second year	7.2	7.7
Third year	2.7	3.8
Fourth year	0.6	0.7
Fifth year	0.1	0.3
Total lease payments, Finance leases	21.7	23.4
Less: Interest	1.1	1.1
Present value of lease liabilities	$ 20.6	$ 22.3
Finance Lease, Liability, Statement of Financial Position	Long-term debt and finance lease obligations, net of debt issuance costs -less current portion, Current portion of long-term debt and finance lease obligations	Long-term debt and finance lease obligations, net of debt issuance costs -less current portion, Current portion of long-term debt and finance lease obligations
Operating Leases
First year	$ 5.7	$ 6.0
Second year	4.8	5.0
Third year	3.4	4.0
Fourth year	2.2	2.7
Fifth year	1.2	1.8
Thereafter	1.3	2.1
Total lease payments, Operating leases	18.6	21.6
Less: Interest	2.1	2.7
Present value of lease liabilities	$ 16.5	$ 18.9
Operating Lease, Liability, Statement of Financial Position	Current portion of long-term lease liability-operating, Long-term lease liability-operating	Current portion of long-term lease liability-operating, Long-term lease liability-operating
Total Finance and Operating Leases
First year	$ 16.8	$ 16.9
Second year	12.0	12.7
Third year	6.1	7.8
Fourth year	2.8	3.4
Fifth year	1.3	2.1
Thereafter	1.3	2.1
Total lease payments	40.3	45.0
Less: Interest	3.2	3.8
Present value of lease liabilities	$ 37.1	$ 41.2