Leases (Lease Expense and Cash Outflows from Operating and Finance Leases) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Finance lease expense:
Depreciation and amortization	$ 19.5	$ 14.4	$ 39.3	$ 36.1
Interest expense	8.3	8.1	16.9	16.2
Total finance lease expense	27.8	22.5	56.2	52.3
Operating lease expense	63.8	29.8	128.4	65.6
Short-term lease expense	1.5	1.5	3.7	3.3
Variable lease expense	1.1	1.1	2.6	2.4
Total lease expense	$ 94.2	$ 54.9	190.9	123.6
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash outflows from operating leases			134.3	60.0
Operating cash outflows from finance leases			16.9	16.2
Financing cash outflows from finance leases			38.1	56.9
Total cash outflows from operating and finance leases			$ 189.3	$ 133.1