v3.26.1
Employee Benefit Plans - Schedule of net periodic costs (Details) - USD ($)
$ in Millions
 12 Months Ended
May 31, 2026
May 31, 2025
May 31, 2024
Components of net periodic (benefit) cost:      
Amortization of net actuarial (gain) loss $ 0.8 $ 0.5 $ 0.4
UNITED KINGDOM | Pension Plans      
Components of net periodic (benefit) cost:      
Interest cost 1.3 1.3 1.3
Expected return on assets (1.1) (1.0) (1.1)
Prior service credit (cost) 0.0 0.0 0.0
Amortization of net actuarial (gain) loss 1.7 1.4 1.3
Net periodic (benefit) cost 1.9 1.7 1.5
United States | Other Postretirement Benefits      
Components of net periodic (benefit) cost:      
Interest cost 0.3 0.3 0.3
Expected return on assets 0.0 0.0 0.0
Prior service credit (cost) (0.8) (0.8) (0.8)
Amortization of net actuarial (gain) loss (0.1) (0.1) 0.0
Net periodic (benefit) cost $ (0.6) $ (0.6) $ (0.5)