Goodwill - Goodwill by Reportable Segment (Detail) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2024	Dec. 31, 2023
Goodwill [Line Items]
Goodwill, gross, Beginning balance	$ 5,585.6	$ 5,599.7
Goodwill, net	3,500.3	3,514.4
Foreign Exchange and Other	(14.1)
Goodwill, gross, Ending balance	5,585.6
Accumulated Impairment Losses	(2,085.3)	(2,085.3)
CCS [Member]
Goodwill [Line Items]
Goodwill, gross, Beginning balance	2,279.4	2,291.0
Goodwill, net	2,128.8	2,140.4
Foreign Exchange and Other	(11.6)
Goodwill, gross, Ending balance	2,279.4
Accumulated Impairment Losses	(150.6)	(150.6)
OWN [Member]
Goodwill [Line Items]
Goodwill, gross, Beginning balance	659.8	662.7
Goodwill, net	500.3	503.2
Foreign Exchange and Other	(2.9)
Goodwill, gross, Ending balance	659.8
Accumulated Impairment Losses	(159.5)	(159.5)
NICS [Member]
Goodwill [Line Items]
Goodwill, gross, Beginning balance	649.0	650.6
Goodwill, net	607.8	609.4
Foreign Exchange and Other	(1.6)
Goodwill, gross, Ending balance	649.0
Accumulated Impairment Losses	(41.2)	(41.2)
ANS [Member]
Goodwill [Line Items]
Goodwill, gross, Beginning balance	1,997.4	1,995.4
Goodwill, net	263.4	261.4
Foreign Exchange and Other	2.0
Goodwill, gross, Ending balance	1,997.4
Accumulated Impairment Losses	$ (1,734.0)	$ (1,734.0)