Property (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Property, Plant and Equipment [Line Items]
Property, gross	$ 1,410.5	$ 1,342.6
Less accumulated depreciation and amortization	(1,024.3)	(933.1)
Property, net	386.2	409.5
Software and software development costs
Property, Plant and Equipment [Line Items]
Property, gross	700.1	654.9
Furniture, fixtures and equipment
Property, Plant and Equipment [Line Items]
Property, gross	432.6	413.3
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property, gross	147.1	143.7
Building and building improvements
Property, Plant and Equipment [Line Items]
Property, gross	$ 130.7	$ 130.7
Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life, minimum	2 years
Minimum [Member] \| Software and software development costs
Property, Plant and Equipment [Line Items]
Estimated useful life, minimum	2 years
Minimum [Member] \| Furniture, fixtures and equipment
Property, Plant and Equipment [Line Items]
Estimated useful life, minimum	2 years
Minimum [Member] \| Leasehold improvements
Property, Plant and Equipment [Line Items]
Estimated useful life, minimum	3 years
Minimum [Member] \| Building and building improvements
Property, Plant and Equipment [Line Items]
Estimated useful life, minimum	1 year
Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life, minimum	20 years
Maximum [Member] \| Software and software development costs
Property, Plant and Equipment [Line Items]
Estimated useful life, minimum	4 years
Maximum [Member] \| Furniture, fixtures and equipment
Property, Plant and Equipment [Line Items]
Estimated useful life, minimum	7 years
Maximum [Member] \| Leasehold improvements
Property, Plant and Equipment [Line Items]
Estimated useful life, minimum	19 years
Maximum [Member] \| Building and building improvements
Property, Plant and Equipment [Line Items]
Estimated useful life, minimum	10 years

Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services.

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