Pension and Post-Employment Benefits - Additional Information (Detail) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Sep. 30, 2024	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Defined Benefit Plan Disclosure [Line Items]
Pension scheme settlement charge		$ 0.0	$ 155.6	$ 0.0
Pension asset		0.0	2.4
Annual cash contribution			0.0
Income tax expense		(21.5)	(5.6)	(35.3)
Amount of unrecognized actuarial net losses, net of tax		0.9	(21.3)	(17.5)
Other Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Amount of contributions to defined contribution schemes		15.3	13.9
United Kingdom Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension asset		0.0	2.5	$ 459.2
Asset		0.0	2.4
Funds to cover pension related costs	$ 8.4	(0.9)	(8.4)
Income tax expense			$ (2.1)
Percentage of asset allocation, actual			100.00%	100.00%
United Kingdom Plan [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Projected Benefit Obligation		0.0	$ 0.1	$ 424.1
Europe [Member] | Performance Chemicals [Member]
Defined Benefit Plan Disclosure [Line Items]
Post-employment obligations European businesses		3.8	4.1
France [Member]
Defined Benefit Plan Disclosure [Line Items]
Amount of unrecognized actuarial net losses, net of tax		$ 0.1	$ 0.2