Leases (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Jan. 01, 2019
Lease Cost [Abstract]
Operating lease cost	$ 317.8
Variable lease cost	38.2
Short-term lease cost	4.9
Sublease income	(5.1)
Finance leases, Amortization of ROU assets	43.2
Finance leases, Interest	5.1
Lease, Cost, Total, Finance Leases	48.3
Total lease cost	404.1
Rent Expense [Abstract]
Operating leases, third-party sublease rent		$ (7.2)	$ (6.3)
Operating leases, Total rent cost		304.4	350.5
Balance Sheet Classification and Weighted Average Remaining Lease Term and Weighted Average Discount Rate for Operating and Finance Leases under ASC 840 [Abstract]
Operating Lease Right-Of-Use Assets	1,398.3	0.0		$ 1,306.5
Operating lease liability, current	290.3
Long-Term Liability - Operating Leases	1,274.7	0.0		$ 1,258.5
Operating lease liability, total	$ 1,565.0
Operating leases, weighted average remaining lease term	8 years 2 months 12 days
Operating leases, weighted average discount rate	3.80%
Finance lease right-of-use assets	$ 138.7
Finance lease liability, current	46.6
Finance lease liability, long-term	92.1
Finance Lease, Liability, Total	$ 138.7
Finance leases, weighted average remaining lease term	3 years 4 months 24 days
Finance leases, weighted average discount rate	4.30%
Maturity of Undiscounted Cash Flows for Operating and Finance Leases [Abstract]
Operating Leases Payments, 2020	$ 344.4
Operating Leases Payments, 2021	289.9
Operating Leases Payments, 2022	233.6
Operating Leases Payments, 2023	178.7
Operating Leases Payments, 2024	155.0
Operating Leases Payments, Thereafter	642.5
Operating Leases, Total lease payments	1,844.1
Operating Leases, Less: Imputed interest	279.1
Operating Leases, Present value of lease liability	1,565.0
Finance Leases Payments, 2020	49.7
Finance Leases Payments, 2021	40.2
Finance Leases Payments, 2022	28.8
Finance Leases Payments, 2023	16.2
Finance Leases Payments, 2024	6.8
Finance Leases Payments, Thereafter	3.9
Finance Leases, Total lease payments	145.6
Finance Leases, Less: Imputed interest	6.9
Finance Leases, Present value of lease liability	$ 138.7
Assets Under Capital Lease and Capital Lease Obligations under ASC 840 [Abstract]
Assets under capital lease, Cost		258.2
Assets under capital lease, Accumulated depreciation		(133.8)
Assets under capital lease		124.4
Capital lease obligations, Current		38.6
Capital lease obligations, Long-term		88.9
Capital lease obligations		127.5
Assets under capital lease, Depreciation expense		36.7	31.1
Office [Member]
Rent Expense [Abstract]
Operating leases, rent		295.0	336.7
Equipment [Member]
Rent Expense [Abstract]
Operating leases, rent		$ 16.6	$ 20.1