Fixed Assets - Schedule of Fixed Assets (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 524.6	$ 476.9
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	(254.3)	(237.0)
Property, Plant and Equipment, Net	270.3	239.9
Furniture Fixtures Equipment and Software
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	345.3	307.2
Leasehold Improvements
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	62.2	61.3
Land, Buildings and Improvements
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 117.1	$ 108.4