Goodwill - Goodwill by Reportable Segment (Detail) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2024	Dec. 31, 2023
Goodwill [Line Items]
Goodwill, gross, Beginning balance	$ 4,832.7	$ 4,823.5
Goodwill, net	2,906.9	2,897.7
Foreign Exchange and Other	9.2
Goodwill, gross, Ending balance	4,832.7
Accumulated Impairment Losses	(1,925.8)	(1,925.8)
CCS [Member]
Goodwill [Line Items]
Goodwill, gross, Beginning balance	2,295.2	2,291.0
Goodwill, net	2,144.6	2,140.4
Foreign Exchange and Other	4.2
Goodwill, gross, Ending balance	2,295.2
Accumulated Impairment Losses	(150.6)	(150.6)
NICS [Member]
Goodwill [Line Items]
Goodwill, gross, Beginning balance	537.7	537.1
Goodwill, net	496.5	495.9
Foreign Exchange and Other	0.6
Goodwill, gross, Ending balance	537.7
Accumulated Impairment Losses	(41.2)	(41.2)
ANS [Member]
Goodwill [Line Items]
Goodwill, gross, Beginning balance	1,999.8	1,995.4
Goodwill, net	265.8	261.4
Foreign Exchange and Other	4.4
Goodwill, gross, Ending balance	1,999.8
Accumulated Impairment Losses	$ (1,734.0)	$ (1,734.0)