v3.25.2
Investments (Portion of Unrealized Gains and Losses Relates to Equity Securities) (Detail) - USD ($)
$ in Millions
 3 Months Ended 6 Months Ended
Jun. 30, 2025
Jun. 30, 2024
Jun. 30, 2025
Jun. 30, 2024
Debt Securities, Available-for-Sale [Line Items]        
Net gains (losses) recognized during the period $ 535 $ 178 $ 296 $ 637
Less: Net (gains) losses recognized during the period on securities sold during the period 10 6 16 (4)
Unrealized gains (losses) recognized during the period on securities still held at period end [1] 545 184 312 633
Virginia Electric and Power Company        
Debt Securities, Available-for-Sale [Line Items]        
Net gains (losses) recognized during the period 274 86 153 328
Less: Net (gains) losses recognized during the period on securities sold during the period 7 4 11 (5)
Unrealized gains (losses) recognized during the period on securities still held at period end [2] $ 281 $ 90 $ 164 $ 323
[1] Included in other income (expense) and the nuclear decommissioning trust regulatory liabilities.
[2] Included in other income (expense) and the nuclear decommissioning trust regulatory liabilities.