Leases - Supplemental Cash Flow Information (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from finance leases	$ 0.0	$ 0.0	$ 0.0	$ 0.1
Financing cash flows from finance leases	0.1	0.2	0.6	0.7
Operating cash flows from operating leases	8.1	6.8	16.0	13.9
Right-of-use assets obtained in exchange for new lease liabilities
Finance leases	0.0	0.0	0.0	0.1
Operating leases	$ 1.7	$ 3.5	$ 42.9	$ 15.6