Leases - Lease Costs (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Finance lease cost
Amortization of right-of-use assets	$ 0.9		$ 1.8
Interest on lease liabilities	0.1		0.3
Operating lease cost	4.4		9.1
Other lease cost	1.1		2.1
Total lease cost	$ 6.5	$ 6.6	$ 13.3	$ 13.0