Leases - Components of Lease Cost (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 cost	$ 1.8	$ 1.8	$ 3.6	$ 3.8
Short-term lease cost	0.3	0.2	0.6	0.5
Amortization of leased assets	0.3	0.3	0.7	0.7
Interest on lease liabilities	0.1	0.1	0.2	0.2
Total lease cost	$ 2.5	$ 2.4	$ 5.1	$ 5.2