Operating Revenue (Schedule of Operating Revenue) (Parenthetical) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Public Utilities General Disclosures [Line Items]
Operating revenue from contracts with customers	$ 14,182	$ 13,487	$ 14,552
Renewable Energy Investment Tax Credits
Public Utilities General Disclosures [Line Items]
Operating revenue from contracts with customers	31	44	42
Transition services agreements
Public Utilities General Disclosures [Line Items]
Other revenues	61	18	28
Alternative Revenue Programs
Public Utilities General Disclosures [Line Items]
Other revenues	129	162	72
Virginia Electric and Power Company
Public Utilities General Disclosures [Line Items]
Operating revenue from contracts with customers	9,959	9,372	9,868
Virginia Electric and Power Company | Renewable Energy Investment Tax Credits
Public Utilities General Disclosures [Line Items]
Operating revenue from contracts with customers	12	29	18
Virginia Electric and Power Company | Alternative Revenue Programs
Public Utilities General Disclosures [Line Items]
Other revenues	$ 129	$ 162	$ 72