Leases - Components of Lease Cost (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Leases [Abstract]
Operating lease cost	$ 2.9	$ 1.8	$ 4.9	$ 3.6
Short-term lease cost	0.8	0.3	1.0	0.6
Amortization of leased assets	0.5	0.3	1.0	0.7
Interest on lease liabilities	0.1	0.1	0.2	0.2
Total lease cost	$ 4.3	$ 2.5	$ 7.1	$ 5.1