Investments (Fair Value of Fixed Income Securities by Contractual Maturity) (Detail) $ in Millions	Jun. 30, 2022 USD ($)
Schedule of Held-to-maturity Securities [Line Items]
Due in one year or less	$ 119
Due after one year through five years	526
Due after five years through ten years	489
Due after ten years	750
Total	1,884
Virginia Electric and Power Company
Schedule of Held-to-maturity Securities [Line Items]
Due in one year or less	69
Due after one year through five years	283
Due after five years through ten years	328
Due after ten years	374
Total	$ 1,054