Leases - Lease Obligations (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Leases [Abstract]
Finance leases - ROU assets	$ 56.2	$ 58.2
Finance leases - Accumulated depreciation	(22.3)	(22.6)
Operating leases - ROU assets	129.1	127.4
Operating leases - Accumulated depreciation	(58.9)	(51.3)
Total lease assets	104.1	111.7
Finance leases	(10.3)	(10.5)
Operating leases	(23.8)	(24.3)
Finance leases	(22.4)	(23.9)
Operating leases	(48.3)	(53.2)
Total lease liabilities	$ (104.8)	$ (111.9)
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	Other non-current assets	Other non-current assets
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	us-gaap:LongTermDebtNoncurrent	us-gaap:LongTermDebtNoncurrent
Finance Lease, Liability, Current, Statement of Financial Position [Extensible List]	us-gaap:LongTermDebtCurrent	us-gaap:LongTermDebtCurrent