Goodwill and Other Identifiable Intangible Assets - Detail of Identifiable Intangible Assets (Detail) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Acquired Intangible Assets By Major Class [Line Items]
Cost	$ 1,197.9	$ 1,195.9
Accumulated amortization	(447.3)	(405.0)
Net	750.6	790.9
Cost	1,450.1	1,447.4
Net	1,002.8	1,042.4
Customer relationships
Acquired Intangible Assets By Major Class [Line Items]
Cost	1,108.1	1,106.2
Accumulated amortization	(399.6)	(361.8)
Net	708.5	744.4
Other
Acquired Intangible Assets By Major Class [Line Items]
Cost	89.8	89.7
Accumulated amortization	(47.7)	(43.2)
Net	42.1	46.5
Trade names intangibles
Acquired Intangible Assets By Major Class [Line Items]
Net, indefinite-life intangibles	$ 252.2	$ 251.5