Operating Revenue (Schedule of Operating Revenue) (Parenthetical) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Public Utilities General Disclosures [Line Items]
Operating revenue from contracts with customers	$ 13,487	$ 14,552	$ 11,661
Renewable Energy Investment Tax Credits
Public Utilities General Disclosures [Line Items]
Operating revenue from contracts with customers	44	42	33
Alternative Revenue Programs
Public Utilities General Disclosures [Line Items]
Other revenues	162	72	44
Virginia Electric and Power Company
Public Utilities General Disclosures [Line Items]
Operating revenue from contracts with customers	9,372	9,868	7,470
Virginia Electric and Power Company | Renewable Energy Investment Tax Credits
Public Utilities General Disclosures [Line Items]
Operating revenue from contracts with customers	29	18	21
Virginia Electric and Power Company | Alternative Revenue Programs
Public Utilities General Disclosures [Line Items]
Other revenues	$ 162	$ 72	$ 44