Leases - Lease Cost (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Leases [Abstract]
Operating lease cost	$ 3.1	$ 3.4	$ 9.3	$ 9.7
Short-term lease cost	0.3	0.1	0.6	0.5
Variable lease cost	1.2	0.8	2.8	2.3
Total lease cost	$ 4.6	$ 4.3	$ 12.7	$ 12.5