v3.26.1
Utility Regulatory Assets and Liabilities and Regulatory Matters - Narrative (Details) - USD ($)
$ in Millions
9 Months Ended 12 Months Ended
Jul. 31, 2026
Jul. 06, 2026
Mar. 27, 2026
Feb. 03, 2026
Jan. 28, 2026
Oct. 28, 2025
Jul. 31, 2025
Jan. 27, 2025
Jul. 31, 2024
Jun. 30, 2026
Jun. 30, 2025
Sep. 30, 2025
Inventory                        
Net gains (losses) on commodity derivative instruments                   $ 55 $ (30)  
2026 Pennsylvania Public Utility Commission For Base Operating Revenues | PAPUC | PA Gas Utility                        
Inventory                        
Net gains (losses) on commodity derivative instruments                   $ (5) $ 1 $ (5)
Pennsylvania Public Utility Commission For Annual Base Distribution Revenues | PAPUC | Electric Utility                        
Inventory                        
Requested rate increase (decrease)     $ 17                  
Pennsylvania Public Utility Commission For Base Operating Revenues | PAPUC | PA Gas Utility                        
Inventory                        
Requested rate increase (decrease)         $ 99     $ 110        
Annual Base Distribution Rate Increase | PAPUC | PA Gas Utility                        
Inventory                        
Approved rate increase (decrease)           $ 70            
Annual Base Distribution Rate Increase | PAPUC | PA Gas Utility | Subsequent event                        
Inventory                        
Requested rate increase (decrease)   $ 65                    
Annual Base Distribution Rate Increase, Effective October 1, 2026 | PAPUC | PA Gas Utility | Subsequent event                        
Inventory                        
Requested rate increase (decrease)   40                    
Annual Base Distribution Rate Increase, Effective October 1, 2027 | PAPUC | PA Gas Utility | Subsequent event                        
Inventory                        
Requested rate increase (decrease)   $ 25                    
Net Revenue Increase | WVPSC | Mountaineer                        
Inventory                        
Requested rate increase (decrease)       $ 27                
Base Rates | WVPSC | Mountaineer                        
Inventory                        
Requested rate increase (decrease)       44                
IREP rate | WVPSC | Mountaineer                        
Inventory                        
Requested rate increase (decrease)       $ (17)                
2026 IREP Expected | WVPSC | Mountaineer | Subsequent event                        
Inventory                        
Requested rate increase (decrease) $ 14                      
Total capital investments 180                      
2026 IREP Expected, Prior Year Under-recovery | WVPSC | Mountaineer | Subsequent event                        
Inventory                        
Requested rate increase (decrease) 9                      
2026 IREP For 2027 | WVPSC | Mountaineer | Subsequent event                        
Inventory                        
Total capital investments 83                      
2026 IREP Recovery | WVPSC | Mountaineer | Subsequent event                        
Inventory                        
Total capital investments $ 475                      
2025 IREP Expected | WVPSC | Mountaineer                        
Inventory                        
Requested rate increase (decrease)             $ 24          
Total capital investments             274          
2025 IREP Expected, Prior Year Under-recovery | WVPSC | Mountaineer                        
Inventory                        
Requested rate increase (decrease)             5          
2025 IREP For 2026 | WVPSC | Mountaineer                        
Inventory                        
Total capital investments             77          
2025 IREP Recovery | WVPSC | Mountaineer                        
Inventory                        
Total capital investments             $ 445          
2024 IREP Expected | WVPSC | Mountaineer                        
Inventory                        
Requested rate increase (decrease)                 $ 19      
Total capital investments                 197      
2024 IREP Expected, Prior Year Under-recovery | WVPSC | Mountaineer                        
Inventory                        
Requested rate increase (decrease)                 3      
2024 IREP For 2025 | WVPSC | Mountaineer                        
Inventory                        
Total capital investments                 74      
2024 IREP Recovery | WVPSC | Mountaineer                        
Inventory                        
Total capital investments                 $ 418