Operating Revenue (Schedule of Operating Revenue) (Parenthetical) (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Public Utilities General Disclosures [Line Items]
Operating revenue from contracts with customers	$ 4,085	$ 3,524
Renewable Energy Investment Tax Credits
Public Utilities General Disclosures [Line Items]
Operating revenue from contracts with customers	10	5
Transition services agreements
Public Utilities General Disclosures [Line Items]
Other revenues	27	4
Alternative Revenue Programs
Public Utilities General Disclosures [Line Items]
Other revenues	22	28
Virginia Electric and Power Company
Public Utilities General Disclosures [Line Items]
Operating revenue from contracts with customers	2,751	2,417
Virginia Electric and Power Company | Renewable Energy Investment Tax Credits
Public Utilities General Disclosures [Line Items]
Operating revenue from contracts with customers	4	2
Virginia Electric and Power Company | Alternative Revenue Programs
Public Utilities General Disclosures [Line Items]
Other revenues	$ 22	$ 28