Leases - Supplemental Cash Flow (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2019
Leases [Abstract]
Operating cash flows from operating leases (a)	$ 38.9	$ 75.2
Operating cash flows from finance leases	0.1	0.2
Financing cash flows from finance leases	0.1	0.2
Leased assets obtained in exchange for new operating lease liabilities	$ 34.7	$ 53.8