Leases (Lease Expense and Cash Outflows from Operating and Finance Leases) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Finance lease expense:
Depreciation and amortization	$ 21.7	$ 22.7
Interest expense	8.1	8.1
Total finance lease expense	29.8	30.8
Operating lease expense	35.8	33.2
Short-term lease expense	1.8	1.9
Variable lease expense	1.3	1.1
Total lease expense	68.7	67.0
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash outflows from operating leases	38.9	35.7
Operating cash outflows from finance leases	8.1	8.1
Financing cash outflows from finance leases	39.2	18.1
Total cash outflows from operating and finance leases	$ 86.2	$ 61.9