v3.26.1
Related-Party Transactions (Parenthetical) (Detail) - Virginia Electric and Power Company - USD ($)
$ in Millions
3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Related Party Transaction [Line Items]        
Capital expenditures     $ 4,769 $ 5,103
Services provided by affiliates | Affiliated Entity        
Related Party Transaction [Line Items]        
Capital expenditures $ 87 $ 71 $ 178 $ 146