Investments (Fair Value of Fixed Income Securities by Contractual Maturity) (Detail) $ in Millions	Jun. 30, 2024 USD ($)
Schedule of Held-to-maturity Securities [Line Items]
Due in one year or less	$ 167
Due after one year through five years	561
Due after five years through ten years	427
Due after ten years	1,015
Total	2,170
Virginia Electric and Power Company
Schedule of Held-to-maturity Securities [Line Items]
Due in one year or less	109
Due after one year through five years	298
Due after five years through ten years	264
Due after ten years	620
Total	$ 1,291