v3.26.1
Pension and Other Postretirement Benefits - Summary of Fair Values of Pension Plan by Assets Category (Details) - Pension Benefits - USD ($)
$ in Millions
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2024
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets at end of year $ 547.1 $ 528.4 $ 471.8
Short-term investments      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets at end of year 5.9 23.2  
Commingled trust funds      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets at end of year 540.8 504.3  
Mortgage/asset backed securities and other      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets at end of year 0.4 0.9  
Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets at end of year 5.9 23.2  
Level 1 | Short-term investments      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets at end of year 5.9 23.2  
Level 1 | Commingled trust funds      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets at end of year 0.0 0.0  
Level 1 | Mortgage/asset backed securities and other      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets at end of year 0.0 0.0  
Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets at end of year 0.4 0.9  
Level 2 | Short-term investments      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets at end of year 0.0 0.0  
Level 2 | Commingled trust funds      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets at end of year 0.0 0.0  
Level 2 | Mortgage/asset backed securities and other      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets at end of year 0.4 0.9  
Net Asset Value      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets at end of year 540.8 504.3  
Net Asset Value | Short-term investments      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets at end of year 0.0 0.0  
Net Asset Value | Commingled trust funds      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets at end of year 540.8 504.3  
Net Asset Value | Mortgage/asset backed securities and other      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets at end of year $ 0.0 $ 0.0