Leases - Financing leases (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Property, Plant and Equipment, Net
Property, plant and equipment, net	$ 1,100.3	$ 1,073.7
Finance lease obligations, Current	$ 14.3
Finance Lease, Liability, Current, Statement of Financial Position [Extensible List]	Long-term Debt and Capital Lease Obligations, Current
Finance lease obligations, Noncurrent	$ 18.6
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	Long-term Debt and Capital Lease Obligations.
Finance leased assets
Property, Plant and Equipment, Net
Property, plant and equipment, net	$ 32.5