v3.26.3
Investments (Portion of Unrealized Gains and Losses Relates to Equity Securities) (Detail) - USD ($)
$ in Millions
 3 Months Ended 9 Months Ended
Sep. 30, 2026
Sep. 30, 2025
Sep. 30, 2026
Sep. 30, 2025
Debt Securities, Available-for-Sale [Line Items]        
Net gains (losses) recognized during the period $ 186 $ 458 $ 812 $ 754
Less: Net (gains) losses recognized during the period on securities sold during the period (9) (1) (4) 15
Unrealized gains (losses) recognized during the period on securities still held at period end [1] 177 457 808 769
Virginia Electric and Power Company        
Debt Securities, Available-for-Sale [Line Items]        
Net gains (losses) recognized during the period 84 236 430 389
Less: Net (gains) losses recognized during the period on securities sold during the period (4) 0 (3) 11
Unrealized gains (losses) recognized during the period on securities still held at period end [2] $ 80 $ 236 $ 427 $ 400
[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.