v3.26.1
Investments (Portion of Unrealized Gains and Losses Relates to Equity Securities) (Detail) - USD ($)
$ in Millions
 3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Debt Securities, Available-for-Sale [Line Items]        
Net gains (losses) recognized during the period $ 885 $ 535 $ 626 $ 296
Less: Net (gains) losses recognized during the period on securities sold during the period (2) 10 5 16
Unrealized gains (losses) recognized during the period on securities still held at period end [1] 883 545 631 312
Virginia Electric and Power Company        
Debt Securities, Available-for-Sale [Line Items]        
Net gains (losses) recognized during the period 472 274 346 153
Less: Net (gains) losses recognized during the period on securities sold during the period (2) 7 1 11
Unrealized gains (losses) recognized during the period on securities still held at period end [2] $ 470 $ 281 $ 347 $ 164
[1] Included in other income (expense) and the nuclear decommissioning trust regulatory liability.
[2] Included in other income (expense) and the nuclear decommissioning trust regulatory liability.