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