Leases - Components of Lease Expense (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Leases [Abstract]
Operating lease expense	$ 4.4	$ 3.7	$ 8.7	$ 7.3
Variable lease expense	0.4	0.6	1.0	1.2
Short-term lease expense	1.0	0.7	1.9	1.4
Total lease expense	$ 5.8	$ 5.0	$ 11.6	$ 9.9