Intangible Assets and Goodwill - Summary of Intangible Assets (Detail) - USD ($) $ in Millions	Mar. 31, 2026	Dec. 31, 2025
Schedule Of Intangible Assets Excluding Goodwill [Line Items]
Gross carrying amount	$ 616.8	$ 615.6
Accumulated amortization	(442.1)	(434.2)
Net carrying amount	174.7	181.4
Trade Names [Member]
Schedule Of Intangible Assets Excluding Goodwill [Line Items]
Gross carrying amount	45.7	45.7
Net carrying amount	45.7	45.7
Customer Relationship Intangibles [Member]
Schedule Of Intangible Assets Excluding Goodwill [Line Items]
Gross carrying amount	391.4	391.9
Accumulated amortization	(359.9)	(356.7)
Net carrying amount	31.5	35.2
Trade Names [Member]
Schedule Of Intangible Assets Excluding Goodwill [Line Items]
Gross carrying amount	111.9	112.2
Accumulated amortization	(36.3)	(34.4)
Net carrying amount	75.6	77.8
Acquired Technology [Member]
Schedule Of Intangible Assets Excluding Goodwill [Line Items]
Gross carrying amount	8.4	8.4
Accumulated amortization	(6.8)	(6.6)
Net carrying amount	1.6	1.8
Acquired Content [Member]
Schedule Of Intangible Assets Excluding Goodwill [Line Items]
Gross carrying amount	2.6	2.6
Accumulated amortization	(2.0)	(1.8)
Net carrying amount	0.6	0.8
Computer Software [Member]
Schedule Of Intangible Assets Excluding Goodwill [Line Items]
Gross carrying amount	54.4	52.9
Accumulated amortization	(37.1)	(34.7)
Net carrying amount	17.3	18.2
Capitalized Software in Progress [Member]
Schedule Of Intangible Assets Excluding Goodwill [Line Items]
Gross carrying amount	2.4	1.9
Net carrying amount	$ 2.4	$ 1.9