Other Financial Information - Property and Equipment, Net (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Property and Equipment [Line Items]
Property and equipment, gross	$ 1,983.0	$ 1,922.5
Accumulated depreciation	(1,293.1)	(1,255.7)
Property and equipment, net	689.9	666.8
Depreciation expense	123.5	137.7	$ 151.0
Computers and equipment
Property and Equipment [Line Items]
Property and equipment, gross	990.0	940.0
Software
Property and Equipment [Line Items]
Property and equipment, gross	221.3	220.3
Leasehold improvements
Property and Equipment [Line Items]
Property and equipment, gross	185.9	189.2
Furniture and fixtures
Property and Equipment [Line Items]
Property and equipment, gross	45.3	45.4
Building and building improvements
Property and Equipment [Line Items]
Property and equipment, gross	292.8	271.9
Land and land improvements
Property and Equipment [Line Items]
Property and equipment, gross	243.6	243.6
Construction-in-process
Property and Equipment [Line Items]
Property and equipment, gross	$ 4.1	$ 12.1