v3.26.3
Fair Value Measurements (Net Change in the Assets and Liabilities Measured at Fair Value on a Recurring Basis and Included in the Level 3 Fair Value Category) (Detail) - USD ($)
$ in Millions
3 Months Ended 9 Months Ended
Sep. 30, 2026
Sep. 30, 2025
Sep. 30, 2026
Sep. 30, 2025
Virginia Electric and Power Company        
Total realized and unrealized gains (losses):        
Sales     $ (9)  
Commodity        
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]        
Beginning balance $ 930 $ 414 627 $ 384
Total realized and unrealized gains (losses):        
Operating revenue (54) (24) (84) (14)
Purchased electric capacity 0 0 (7) 0
Included in earnings $ (46) $ 115 $ 206 $ 233
Fair Value, Net Derivative Asset (Liability), Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration] Electric fuel and other energy-related purchases Electric fuel and other energy-related purchases Electric fuel and other energy-related purchases Electric fuel and other energy-related purchases
Purchased gas $ (3) $ 0 $ (3) $ 0
Included in regulatory assets/liabilities (210) 33 (47) 76
Settlements 21 (126) (275) (275)
Purchases 0 0 221 8
Sales (9)   (9)  
Transfers out of Level 3 0 (1) 0 (1)
Ending balance 629 411 629 411
Commodity | Virginia Electric and Power Company        
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]        
Beginning balance 315 179 208 68
Total realized and unrealized gains (losses):        
Purchased electric capacity 0 0 (7) 0
Included in earnings (58) 106 186 222
Included in regulatory assets/liabilities (251) (11) (151) 102
Settlements 58 (106) (183) (232)
Purchases 0 0 11 8
Sales (9)      
Ending balance $ 55 $ 168 $ 55 $ 168