Leases - Components of Lease Cost (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Leases [Abstract]
Operating lease cost	$ 2.8	$ 1.6	$ 7.7	$ 5.2
Short-term lease cost	1.5	0.5	2.5	1.1
Amortization of leased assets	0.5	0.5	1.5	1.2
Interest on lease liabilities			0.2	0.2
Total lease cost	$ 4.8	$ 2.6	$ 11.9	$ 7.7