Operating Revenue (Schedule of Operating Revenue) (Parenthetical) (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Public Utilities General Disclosures [Line Items]
Operating revenue from contracts with customers	$ 3,455	$ 3,080	$ 6,979	$ 6,532
Renewable Energy Investment Tax Credits
Public Utilities General Disclosures [Line Items]
Operating revenue from contracts with customers	7	24	12	29
Alternative Revenue Programs
Public Utilities General Disclosures [Line Items]
Other revenues	33	50	61	77
Virginia Electric and Power Company
Public Utilities General Disclosures [Line Items]
Operating revenue from contracts with customers	2,468	2,189	4,885	4,535
Virginia Electric and Power Company | Renewable Energy Investment Tax Credits
Public Utilities General Disclosures [Line Items]
Operating revenue from contracts with customers	$ 3	$ 19	$ 5	$ 22