Contingencies, Guarantees, Indemnifications and Leases - Leases (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Assets
Operating lease assets	$ 190.0
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	Property, Plant and Equipment, Net
Finance lease assets	$ 31.4
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	Property, Plant and Equipment, Net
Total lease assets	$ 221.4
Liabilities
Operating lease liabilities	$ 197.5
Operating Lease, Liability, Statement of Financial Position [Extensible List]	Other Liabilities
Finance lease liabilities	$ 31.8
Finance Lease, Liability, Statement of Financial Position [Extensible List]	Other Liabilities
Total lease liabilities	$ 229.3
Capital lease assets		$ 32.6
Finance lease cost:
Amortization of right-of-use assets	14.6
Interest on lease liabilities	1.0
Operating lease cost	55.8
Other lease cost	8.0
Sublease income	(1.7)
Total lease cost	77.7
Operating lease rental expense		36.7	$ 44.0
Capital lease depreciation expense		$ 12.9	$ 13.4
Payments for operating leases	56.1
Payments for finance leases	15.1
Operating leases, payments due for the twelve months ending December 31:
2020	53.9
2021	43.7
2022	35.3
2023	25.9
2024	18.3
2025 and thereafter	51.7
Total lease payments	228.8
Less: interest	31.3
Present value of lease liabilities	197.5
Finance leases, payments due for the twelve months ending December 31:
2020	14.8
2021	11.7
2022	3.9
2023	1.9
2024	0.5
2025 and thereafter	0.1
Total lease payments	32.9
Less: interest	1.1
Present value of lease liabilities	31.8
Total leases, payments due for the twelve months ending December 31:
2020	68.7
2021	55.4
2022	39.2
2023	27.8
2024	18.8
2025 and thereafter	51.8
Total lease payments	261.7
Less: interest	32.4
Present value of lease liabilities	$ 229.3
Weighted-average remaining lease term and weighted-average discount rates
Weighted average remaining lease term, Operating leases	6 years 8 months 12 days
Weighted average remaining lease term, Finance leases	2 years 7 months 6 days
Weighted-average discount rate, Operating leases	3.90%
Weighted-average discount rate, Finance leases	2.70%