Investments (Fair Value of Fixed Income Securities by Contractual Maturity) (Detail) $ in Millions	Dec. 31, 2024 USD ($)
Schedule of Held-to-maturity Securities [Line Items]
Due in one year or less	$ 7
Due after one year through five years	565
Due after five years through ten years	441
Due after ten years	1,198
Total	2,211
Virginia Electric and Power Company
Schedule of Held-to-maturity Securities [Line Items]
Due in one year or less	7
Due after one year through five years	294
Due after five years through ten years	251
Due after ten years	766
Total	$ 1,318