Employee Retirement Plans - Other Changes in Plan Assets And Benefit Obligations Recognized in OCI (Detail) - USD ($) $ in Millions	12 Months Ended
	May 31, 2024	May 31, 2023
Pension Benefit
Defined Benefit Plan Disclosure [Line Items]
Net (gain) loss	$ (3.4)	$ 1.3
Amortization of net (gain) loss	0.3	0.2
Total recognized in other comprehensive income	(3.1)	1.5
Total recognized in net periodic benefit cost (income) and OCI	(3.8)	0.8
Other Benefits
Defined Benefit Plan Disclosure [Line Items]
Net (gain) loss	(0.2)	(0.3)
Amortization of net (gain) loss	0.1	(0.4)
Total recognized in other comprehensive income	(0.1)	(0.7)
Total recognized in net periodic benefit cost (income) and OCI	$ 0.0	$ (0.5)