Leases - 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	$ 3.3	$ 3.1	$ 9.5	$ 9.3
Short-term lease cost	0.4	0.3	0.9	0.6
Variable lease cost	1.1	1.2	3.3	2.8
Total lease cost	$ 4.8	$ 4.6	$ 13.7	$ 12.7