Employee Retirement Plans - Other Changes in Plan Assets And Benefit Obligations Recognized in OCI (Detail) - USD ($) $ in Millions	12 Months Ended
	May 31, 2025	May 31, 2024
Pension Benefit
Defined Benefit Plan Disclosure [Line Items]
Net (gain)/loss	$ (1.7)	$ (3.4)
Amortization of net gain/(loss)	0.3	0.3
Settlement gain	2.7	0.0
Total recognized in other comprehensive loss/(income)	1.3	(3.1)
Total recognized in net periodic benefit cost (income) and OCI	(1.9)	(3.8)
Other Benefits
Defined Benefit Plan Disclosure [Line Items]
Net (gain)/loss	(0.1)	(0.2)
Amortization of net gain/(loss)	0.2	0.1
Settlement gain	0.0	0.0
Total recognized in other comprehensive loss/(income)	0.1	(0.1)
Total recognized in net periodic benefit cost (income) and OCI	$ 0.1	$ 0.0