Derivatives and Hedge Accounting Activities (Volume of Derivative Activity) (Detail) - 12 months ended Dec. 31, 2023 € in Millions, kr in Millions, $ in Millions		USD ($) MWh Bcf	DKK (kr)	EUR (€)
Fixed Price - Natural Gas - Current Derivative Contract
Derivative [Line Items]
Volume of derivative activity | Bcf	[1]	38
Fixed Price - Natural Gas - Current Derivative Contract | Virginia Electric and Power Company
Derivative [Line Items]
Volume of derivative activity | Bcf	[1]	32
Basis - Natural Gas - Current Derivative Contract
Derivative [Line Items]
Volume of derivative activity | Bcf	[1]	179
Basis - Natural Gas - Current Derivative Contract | Virginia Electric and Power Company
Derivative [Line Items]
Volume of derivative activity | Bcf	[1]	141
Fixed Price - Electricity - Current Derivative Contract
Derivative [Line Items]
Volume of electricity | MWh		17
Fixed Price - Electricity - Current Derivative Contract | Virginia Electric and Power Company
Derivative [Line Items]
Volume of electricity | MWh		8
Financial Transmission Rights - Electricity- Current Derivative Contract
Derivative [Line Items]
Volume of electricity | MWh		39
Financial Transmission Rights - Electricity- Current Derivative Contract | Virginia Electric and Power Company
Derivative [Line Items]
Volume of electricity | MWh		39
Interest Rate - Current Derivative Contract
Derivative [Line Items]
Derivative payment | $	[2]	$ 6,145
Interest Rate - Current Derivative Contract | Virginia Electric and Power Company
Derivative [Line Items]
Derivative payment | $	[2]	$ 2,200
Foreign Currency Exchange Rate - Current Derivative Contract
Derivative [Line Items]
Derivative payment	[2]		kr 1,463	€ 548
Foreign Currency Exchange Rate - Current Derivative Contract | Virginia Electric and Power Company
Derivative [Line Items]
Derivative payment	[2]		1,463	548
Fixed Price - Natural Gas - Non-current Derivative Contract
Derivative [Line Items]
Volume of derivative activity | Bcf	[1]	14
Fixed Price - Natural Gas - Non-current Derivative Contract | Virginia Electric and Power Company
Derivative [Line Items]
Volume of derivative activity | Bcf	[1]	14
Basis - Natural Gas - Non-current Derivative Contract
Derivative [Line Items]
Volume of derivative activity | Bcf	[1]	346
Basis - Natural Gas - Non-current Derivative Contract | Virginia Electric and Power Company
Derivative [Line Items]
Volume of derivative activity | Bcf	[1]	346
Fixed Price - Electricity - Non-current Derivative Contract
Derivative [Line Items]
Volume of electricity | MWh		40
Fixed Price - Electricity - Non-current Derivative Contract | Virginia Electric and Power Company
Derivative [Line Items]
Volume of electricity | MWh		9
Financial Transmission Rights - Electricity- Non-current Derivative Contract
Derivative [Line Items]
Volume of electricity | MWh		0
Financial Transmission Rights - Electricity- Non-current Derivative Contract | Virginia Electric and Power Company
Derivative [Line Items]
Volume of electricity | MWh		0
Interest Rate - Non-current Derivative Contract
Derivative [Line Items]
Derivative payment | $	[2]	$ 10,112
Interest Rate - Non-current Derivative Contract | Virginia Electric and Power Company
Derivative [Line Items]
Derivative payment | $	[2]	$ 1,050
Foreign Currency Exchange Rate - Non-current Derivative Contract
Derivative [Line Items]
Derivative payment	[2]		2,707	1,557
Foreign Currency Exchange Rate - Non-current Derivative Contract | Virginia Electric and Power Company
Derivative [Line Items]
Derivative payment	[2]		kr 2,707	€ 1,557

[1] Includes options.

[2] Maturity is determined based on final settlement period.