Leases (Lease Expense and Cash Outflows from Operating and Finance Leases) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Finance lease expense:
Depreciation and amortization	$ 13.6	$ 16.8	$ 52.6	$ 52.7
Interest expense	5.4	7.7	22.1	23.6
Total finance lease expense	19.0	24.5	74.7	76.3
Operating lease expense	38.5	16.4	164.7	79.6
Short-term lease expense	1.1	0.9	4.0	3.1
Variable lease expense	0.4	0.3	1.6	1.1
Total lease expense	$ 59.0	$ 42.1	245.0	160.1
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash outflows from operating leases			164.1	72.6
Operating cash outflows from finance leases			22.1	23.6
Financing cash outflows from finance leases			52.0	75.2
Total cash outflows from operating and finance leases			$ 238.2	$ 171.4