v3.26.3
Derivatives and Hedge Accounting Activities (Schedule of Derivatives not Designated as Hedging Instruments) (Detail) - Derivatives Not Designated as Hedging Instruments - USD ($)
$ in Millions
 3 Months Ended 9 Months Ended
Sep. 30, 2026
Sep. 30, 2025
Sep. 30, 2026
Sep. 30, 2025
Derivative Instruments Gain Loss [Line Items]        
Amount of Gain (Loss) Recognized in Income on Derivatives [1],[2] $ (41) $ 71 $ 74 $ 150
Virginia Electric and Power Company        
Derivative Instruments Gain Loss [Line Items]        
Amount of Gain (Loss) Recognized in Income on Derivatives [1],[2] (74) 87 180 169
Commodity | Location, Statement of Income, Balance [Axis]: us-gaap:Revenues        
Derivative Instruments Gain Loss [Line Items]        
Amount of Gain (Loss) Recognized in Income on Derivatives [1],[2] (23) (31) (226) (47)
Commodity | Location, Statement of Income, Balance [Axis]: us-gaap:Revenues | Virginia Electric and Power Company        
Derivative Instruments Gain Loss [Line Items]        
Amount of Gain (Loss) Recognized in Income on Derivatives [1],[2] 0 (8) 0 (27)
Commodity | Location, Statement of Income, Balance [Axis]: d:ElectricFuelAndOtherEnergyRelatedPurchases        
Derivative Instruments Gain Loss [Line Items]        
Amount of Gain (Loss) Recognized in Income on Derivatives [1],[2] (60) 102 215 207
Commodity | Location, Statement of Income, Balance [Axis]: d:ElectricFuelAndOtherEnergyRelatedPurchases | Virginia Electric and Power Company        
Derivative Instruments Gain Loss [Line Items]        
Amount of Gain (Loss) Recognized in Income on Derivatives [1],[2] (74) 95 187 196
Commodity | Location, Statement of Income, Balance [Axis]: d:PurchasedExcessElectricCapacity        
Derivative Instruments Gain Loss [Line Items]        
Amount of Gain (Loss) Recognized in Income on Derivatives [1],[2] 0 0 (7) 0
Commodity | Location, Statement of Income, Balance [Axis]: d:PurchasedExcessElectricCapacity | Virginia Electric and Power Company        
Derivative Instruments Gain Loss [Line Items]        
Amount of Gain (Loss) Recognized in Income on Derivatives [1],[2] 0 0 (7) 0
Commodity | Location, Statement of Income, Balance [Axis]: d:PurchasedExcessGas        
Derivative Instruments Gain Loss [Line Items]        
Amount of Gain (Loss) Recognized in Income on Derivatives [1],[2] (1) (1) 1 (1)
Interest Rate Contract | Location, Statement of Income, Balance [Axis]: us-gaap:InterestAndDebtExpense        
Derivative Instruments Gain Loss [Line Items]        
Amount of Gain (Loss) Recognized in Income on Derivatives [1],[2] $ 43 $ 1 $ 91 $ (9)
[1] Excludes amounts related to foreign currency exchange rate derivatives that are deferred to regulatory assets/liabilities that will begin to amortize as
the CVOW Commercial Project is placed in service.
[2] Includes derivative activity amortized out of regulatory assets/liabilities. Amounts deferred into regulatory assets/liabilities have no associated effect in the Companies’ Consolidated Statements of Income.