Goodwill and Intangible Assets - Schedule of Computer Software and Goodwill (Details) - USD ($) $ in Millions	3 Months Ended
	Jun. 30, 2024	Mar. 31, 2024	Jun. 30, 2023	Mar. 31, 2023
Computer software
Balance at beginning of period	$ 671.4	$ 666.3	$ 642.8	$ 631.8
Additions at cost	54.9	52.5	52.2	44.0
Amortization	(41.4)	(40.7)	(37.4)	(34.9)
Impairment / Write-off	(0.2)		(0.9)	(0.3)
Other	0.0	(6.7)	0.0	2.2
Balance at end of period	684.7	671.4	656.7	642.8
Goodwill
Balance at beginning of period	3,424.7	3,445.8	3,435.7	3,431.3
Other	1.9	(21.1)	(13.3)	4.4
Balance at end of period	$ 3,426.6	$ 3,424.7	$ 3,422.4	$ 3,435.7