v3.26.1
Pension and Other Postretirement Benefits - Summary of Fair Values of Other Postretirement Benefit Plans by Asset Category (Details) - Other Postretirement Plans - 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 $ 159.2 $ 143.3 $ 136.3
Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets at end of year 3.0 0.6  
Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets at end of year 0.0 0.0  
Net Asset Value      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets at end of year 156.2 142.7  
Commingled trust funds      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets at end of year 156.2 142.7  
Commingled trust funds | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets at end of year 0.0 0.0  
Commingled trust funds | Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets at end of year 0.0 0.0  
Commingled trust funds | Net Asset Value      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets at end of year 156.2 142.7  
Short-term investments      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets at end of year 3.0 0.6  
Short-term investments | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets at end of year 3.0 0.6  
Short-term investments | Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets at end of year 0.0 0.0  
Short-term investments | Net Asset Value      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets at end of year $ 0.0 $ 0.0