Employee Retirement Plans - Components of Net Periodic Pension Income for Defined Benefit Pension Plans (Detail) - USD ($) $ in Millions	12 Months Ended
	May 31, 2025	May 31, 2024	May 31, 2023
Retirement Benefits [Abstract]
Interest cost	$ 2.9	$ 3.6	$ 3.4
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Interest Cost, Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)
Expected return on plan assets	$ (3.0)	$ (4.0)	$ (3.9)
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit, Expected Return (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)
Net amortization and deferral costs	$ (0.3)	$ (0.3)	$ (0.1)
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit, Amortization of Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)
Settlement gain	$ (2.7)	$ 0.0	$ 0.0
Net periodic benefit income	$ (3.1)	$ (0.7)	$ (0.6)