Segment Information - Schedule of Other Selected Segment Financial Information and Supplemental Geographic and Disaggregated Revenue Information (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Jun. 30, 2024	Mar. 31, 2024	Dec. 31, 2023	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022
Revenues from External Customers and Long-Lived Assets [Line Items]
Depreciation and amortization	$ 144.8	$ 146.7	$ 430.1	$ 437.1
Capital expenditures:	1.7	1.1	3.8	3.7
Additions to computer software and other intangibles:	44.3	34.3	153.7	126.2
Assets:	9,004.9		9,004.9				$ 9,135.9
Goodwill:	3,447.5	3,413.9	3,447.5	3,413.9	$ 3,426.6	$ 3,424.7	3,445.8	$ 3,422.4	$ 3,435.7	$ 3,431.3
Other intangibles:	3,629.4	3,998.4	3,629.4	3,998.4	$ 3,709.6	$ 3,805.2	3,915.9	$ 4,113.3	$ 4,218.6	$ 4,320.1
Other long-lived assets:	1,200.5		1,200.5				1,100.7
Total long-lived assets	8,277.4		8,277.4				8,462.4
Deferred income tax	17.3		17.3				17.2
Operating Segments
Revenues from External Customers and Long-Lived Assets [Line Items]
Depreciation and amortization	35.2	29.4	98.8	82.1
Capital expenditures:	1.6	1.1	3.7	3.2
Additions to computer software and other intangibles:	43.6	22.4	139.5	105.6
Corporate and other
Revenues from External Customers and Long-Lived Assets [Line Items]
Depreciation and amortization	109.6	117.3	331.3	355.0
Capital expenditures:	0.1	0.0	0.1	0.5
Additions to computer software and other intangibles:	0.7	11.9	14.2	20.6
North America
Revenues from External Customers and Long-Lived Assets [Line Items]
Assets:	7,404.9		7,404.9				7,643.3
Goodwill:	2,929.6		2,929.6				2,929.6
Other intangibles:	3,205.3		3,205.3				3,451.5
Other long-lived assets:	970.1		970.1				891.6
North America | Operating Segments
Revenues from External Customers and Long-Lived Assets [Line Items]
Depreciation and amortization	28.4	24.3	80.1	66.8
Capital expenditures:	0.2	0.5	0.9	1.9
Additions to computer software and other intangibles:	36.9	16.4	117.4	85.1
International
Revenues from External Customers and Long-Lived Assets [Line Items]
Assets:	1,600.0		1,600.0				1,492.6
Goodwill:	517.9		517.9				516.2
Other intangibles:	424.1		424.1				464.4
Other long-lived assets:	230.4		230.4				$ 209.1
International | Operating Segments
Revenues from External Customers and Long-Lived Assets [Line Items]
Depreciation and amortization	6.8	5.1	18.7	15.3
Capital expenditures:	1.4	0.6	2.8	1.3
Additions to computer software and other intangibles:	$ 6.7	$ 6.0	$ 22.1	$ 20.5