v3.26.1
Accumulated Other Comprehensive Income (Loss) - Reclassification out of AOCI (Details) - USD ($)
$ in Millions
 12 Months Ended
May 31, 2026
May 31, 2025
May 31, 2024
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]      
Other components of net periodic benefit (cost) $ 1.3 $ 1.1 $ 1.0
Tax (benefit) expense 28.5 0.6 4.1
Pension Plans | Amount reclassified from Accumulated other comprehensive income (loss)      
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]      
Net income (loss) 1.7 1.4 1.3
Postretirement Benefits | Amount reclassified from Accumulated other comprehensive income (loss)      
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]      
Net income (loss) (0.7) (0.7) (0.6)
Amortization of prior service (credit) loss | Pension Plans | Amount reclassified from Accumulated other comprehensive income (loss)      
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]      
Other components of net periodic benefit (cost) 0.0 0.0 0.0
Amortization of prior service (credit) loss | Postretirement Benefits | Amount reclassified from Accumulated other comprehensive income (loss)      
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]      
Other components of net periodic benefit (cost) (0.8) (0.8) (0.8)
Amortization of net actuarial loss (gain) | Pension Plans | Amount reclassified from Accumulated other comprehensive income (loss)      
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]      
Other components of net periodic benefit (cost) 1.7 1.4 1.3
Amortization of net actuarial loss (gain) | Postretirement Benefits | Amount reclassified from Accumulated other comprehensive income (loss)      
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]      
Other components of net periodic benefit (cost) (0.1) (0.1) 0.0
Tax (benefit) expense | Pension Plans | Amount reclassified from Accumulated other comprehensive income (loss)      
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]      
Tax (benefit) expense 0.0 0.0 0.0
Tax (benefit) expense | Postretirement Benefits | Amount reclassified from Accumulated other comprehensive income (loss)      
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]      
Tax (benefit) expense $ 0.2 $ 0.2 $ 0.2