Leases (Lease Expense and Cash Outflows from Operating and Finance Leases) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Finance lease expense:
Depreciation and amortization	$ 17.0	$ 19.7	$ 53.1	$ 65.0
Interest expense	7.8	8.4	24.0	25.4
Total finance lease expense	24.8	28.1	77.1	90.4
Operating lease expense	34.2	36.5	99.8	103.8
Short-term lease expense	1.6	2.0	4.9	6.0
Variable lease expense	1.1	1.2	3.5	3.5
Total lease expense	$ 61.7	$ 67.8	185.3	203.7
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash outflows from operating leases			94.5	105.7
Operating cash outflows from finance leases			24.0	25.4
Financing cash outflows from finance leases			75.8	53.7
Total cash outflows from operating and finance leases			$ 194.3	$ 184.8