Employee Benefit Plans Net Periodic Benefit Cost (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2026	Sep. 30, 2025	Sep. 30, 2026	Sep. 30, 2025
Other Postretirement Benefit Plans
Defined Benefit Plans and Other Postretirement Benefit Plans
Amortization of Prior Service Credit	$ (0.1)	$ (0.1)
U.S. Pension Plan | Pension Plan
Defined Benefit Plans and Other Postretirement Benefit Plans
Service Cost	1.7	2.3	$ 5.5	$ 7.0
Interest Cost	16.4	21.4	49.2	64.2
Expected Return on Plan Assets	(16.6)	(21.8)	(50.0)	(65.4)
Amortization of Net Actuarial (Gain) Loss	2.2	3.8	6.5	11.2
Amortization of Prior Service Credit	0.0	0.0	0.0	0.0
Net Periodic Benefit Cost (Credit)	3.7	5.7	11.2	17.0
U.K. Pension Plan | Pension Plan
Defined Benefit Plans and Other Postretirement Benefit Plans
Service Cost	0.0	0.0	0.0	0.0
Interest Cost	2.2	2.2	6.6	6.5
Expected Return on Plan Assets	(2.5)	(2.2)	(7.5)	(6.6)
Amortization of Net Actuarial (Gain) Loss	0.7	0.7	2.1	2.1
Amortization of Prior Service Credit	0.0	0.0	0.0	0.0
Net Periodic Benefit Cost (Credit)	0.4	0.7	1.2	2.0
Other Postretirement Benefit Plan | Other Postretirement Benefit Plans
Defined Benefit Plans and Other Postretirement Benefit Plans
Service Cost	0.0	0.0	0.0	0.0
Interest Cost	0.9	1.0	2.7	3.0
Expected Return on Plan Assets	(0.1)	(0.1)	(0.3)	(0.3)
Amortization of Net Actuarial (Gain) Loss	(0.2)	(0.3)	(0.7)	(0.9)
Amortization of Prior Service Credit			(0.2)	(0.2)
Net Periodic Benefit Cost (Credit)	$ 0.5	$ 0.5	$ 1.5	$ 1.6