v3.25.2
Derivatives and Hedge Accounting Activities (Volume of Derivative Activity) (Detail) - 6 months ended Jun. 30, 2025
USD ($)
MWh
Bcf
DKK (kr)
EUR (€)
Fixed Price - Natural Gas - Current Derivative Contract      
Derivative [Line Items]      
Volume of derivative activity 35    
Fixed Price - Natural Gas - Current Derivative Contract | Virginia Electric and Power Company      
Derivative [Line Items]      
Volume of derivative activity 32    
Basis - Natural Gas - Current Derivative Contract      
Derivative [Line Items]      
Volume of derivative activity [1] 181    
Basis - Natural Gas - Current Derivative Contract | Virginia Electric and Power Company      
Derivative [Line Items]      
Volume of derivative activity [1] 145    
Fixed Price - Electricity - Current Derivative Contract      
Derivative [Line Items]      
Volume of electricity | MWh 14    
Fixed Price - Electricity - Current Derivative Contract | Virginia Electric and Power Company      
Derivative [Line Items]      
Volume of electricity | MWh 4    
Financial Transmission Rights - Electricity- Current Derivative Contract      
Derivative [Line Items]      
Volume of electricity | MWh 90    
Financial Transmission Rights - Electricity- Current Derivative Contract | Virginia Electric and Power Company      
Derivative [Line Items]      
Volume of electricity | MWh 90    
Interest Rate - Current Derivative Contract      
Derivative [Line Items]      
Derivative payment | $ [2] $ 473,000,000    
Interest Rate - Current Derivative Contract | Virginia Electric and Power Company      
Derivative [Line Items]      
Derivative payment | $ [2] $ 190,000,000    
Foreign Currency Exchange Rate - Current Derivative Contract      
Derivative [Line Items]      
Derivative payment [2]   kr 1,690,000,000 € 683,000,000
Foreign Currency Exchange Rate - Current Derivative Contract | Virginia Electric and Power Company      
Derivative [Line Items]      
Derivative payment [2]   1,690,000,000 683,000,000
Fixed Price - Natural Gas - Non-current Derivative Contract      
Derivative [Line Items]      
Volume of derivative activity 17    
Fixed Price - Natural Gas - Non-current Derivative Contract | Virginia Electric and Power Company      
Derivative [Line Items]      
Volume of derivative activity 17    
Basis - Natural Gas - Non-current Derivative Contract      
Derivative [Line Items]      
Volume of derivative activity [1] 322    
Basis - Natural Gas - Non-current Derivative Contract | Virginia Electric and Power Company      
Derivative [Line Items]      
Volume of derivative activity [1] 296    
Fixed Price - Electricity - Non-current Derivative Contract      
Derivative [Line Items]      
Volume of electricity | MWh 32    
Interest Rate - Non-current Derivative Contract      
Derivative [Line Items]      
Derivative payment | $ [2] $ 9,649,000,000    
Interest Rate - Non-current Derivative Contract | Virginia Electric and Power Company      
Derivative [Line Items]      
Derivative payment | $ [2] $ 5,285,000,000    
Foreign Currency Exchange Rate - Non-current Derivative Contract      
Derivative [Line Items]      
Derivative payment [2]   292,000,000 128,000,000
Foreign Currency Exchange Rate - Non-current Derivative Contract | Virginia Electric and Power Company      
Derivative [Line Items]      
Derivative payment [2]   kr 292,000,000 € 128,000,000
[1] Includes options.
[2] Maturity is determined based on final settlement period.