Summary of Significant Accounting Policies (Details) $ in Millions	12 Months Ended
	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Jan. 01, 2019 USD ($)
Operating Lease, Right-of-Use Asset	$ 1,544.4	$ 1,379.3		$ 1,421.1
Operating Lease, Liability	1,841.8			$ 1,544.4
Revenue, remaining performance obligation, amount	$ 605.1
ERP Systems, Useful Life	10
Minimum Remaining Lease Term	1 year
Maximum Remaining Lease Term	15 years
Leasehold Improvements, Useful Life	the shorter of the useful life or the remaining lease term
Number of Reporting Units for Purposes of Annual Goodwill Impairment Test	9
Foreign Currency Transaction pre-tax Gain (Loss)	$ 5.0	$ (1.2)	$ 5.3
Minimum
Furniture and Equipment, Useful Life	3 years
Buildings, Useful Life	10 years
Other Internal Use Software, Useful Life	3
Identifiable Intangible Assets, Useful Life	7 years
Maximum
Furniture and Equipment, Useful Life	7 years
Buildings, Useful Life	35 years
Other Internal Use Software, Useful Life	7
Identifiable Intangible Assets, Useful Life	15 years