Derivatives and Hedge Accounting Activities (Volume of Derivative Activity) (Detail) - 3 months ended Mar. 31, 2025		USD ($) MWh Bcf	DKK (kr)	EUR (€)
Fixed Price - Natural Gas - Current Derivative Contract
Derivative [Line Items]
Volume of derivative activity		23
Fixed Price - Natural Gas - Current Derivative Contract | Virginia Electric and Power Company
Derivative [Line Items]
Volume of derivative activity		23
Basis - Natural Gas - Current Derivative Contract
Derivative [Line Items]
Volume of derivative activity	[1]	192
Basis - Natural Gas - Current Derivative Contract | Virginia Electric and Power Company
Derivative [Line Items]
Volume of derivative activity	[1]	151
Fixed Price - Electricity - Current Derivative Contract
Derivative [Line Items]
Volume of electricity | MWh		16
Fixed Price - Electricity - Current Derivative Contract | Virginia Electric and Power Company
Derivative [Line Items]
Volume of electricity | MWh		7
Financial Transmission Rights - Electricity- Current Derivative Contract
Derivative [Line Items]
Volume of electricity | MWh		18
Financial Transmission Rights - Electricity- Current Derivative Contract | Virginia Electric and Power Company
Derivative [Line Items]
Volume of electricity | MWh		18
Interest Rate - Current Derivative Contract
Derivative [Line Items]
Derivative payment | $	[2]	$ 1,137,000,000
Interest Rate - Current Derivative Contract | Virginia Electric and Power Company
Derivative [Line Items]
Derivative payment | $	[2]	$ 112,000,000
Foreign Currency Exchange Rate - Current Derivative Contract
Derivative [Line Items]
Derivative payment	[2]		kr 1,944,000,000	€ 106,000,000
Foreign Currency Exchange Rate - Current Derivative Contract | Virginia Electric and Power Company
Derivative [Line Items]
Derivative payment	[2]		1,944,000,000	106,000,000
Fixed Price - Natural Gas - Non-current Derivative Contract
Derivative [Line Items]
Volume of derivative activity		18
Fixed Price - Natural Gas - Non-current Derivative Contract | Virginia Electric and Power Company
Derivative [Line Items]
Volume of derivative activity		18
Basis - Natural Gas - Non-current Derivative Contract
Derivative [Line Items]
Volume of derivative activity	[1]	352
Basis - Natural Gas - Non-current Derivative Contract | Virginia Electric and Power Company
Derivative [Line Items]
Volume of derivative activity	[1]	321
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]	$ 12,476,000,000
Interest Rate - Non-current Derivative Contract | Virginia Electric and Power Company
Derivative [Line Items]
Derivative payment | $	[2]	$ 3,363,000,000
Foreign Currency Exchange Rate - Non-current Derivative Contract
Derivative [Line Items]
Derivative payment	[2]		419,000,000	832,000,000
Foreign Currency Exchange Rate - Non-current Derivative Contract | Virginia Electric and Power Company
Derivative [Line Items]
Derivative payment	[2]		kr 419,000,000	€ 832,000,000

[1] Includes options.

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