Leases - Lease Costs (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2019
Operating Lease Cost
Fixed lease cost	$ 9.2	$ 18.5
Short-term lease cost	10.6	20.7
Variable lease cost	4.7	8.9
Lease, Cost [Abstract]
Amortization of leased assets	1.4	2.7
Interest on leased liabilities	1.8	3.7
Variable lease cost	1.3	2.7
Total lease cost	$ 29.0	$ 57.2