Derivatives and Hedge Accounting Activities (Volume of Derivative Activity) (Detail) - 9 months ended Sep. 30, 2022 € 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]	47
Fixed Price - Natural Gas - Current Derivative Contract | Virginia Electric and Power Company
Derivative [Line Items]
Volume of derivative activity | Bcf		34
Basis - Natural Gas - Current Derivative Contract
Derivative [Line Items]
Volume of derivative activity | Bcf	[1]	159
Basis - Natural Gas - Current Derivative Contract | Virginia Electric and Power Company
Derivative [Line Items]
Volume of derivative activity | Bcf	[1]	145
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		8
Financial Transmission Rights - Electricity- Current Derivative Contract
Derivative [Line Items]
Volume of electricity | MWh		72
Financial Transmission Rights - Electricity- Current Derivative Contract | Virginia Electric and Power Company
Derivative [Line Items]
Volume of electricity | MWh		72
Oil - Current Derivative Contract
Derivative [Line Items]
Derivative payment | $		$ 6
Oil - Current Derivative Contract | Virginia Electric and Power Company
Derivative [Line Items]
Derivative payment | $		6
Interest Rate - Current Derivative Contract
Derivative [Line Items]
Derivative payment | $	[2]	358
Interest Rate - Current Derivative Contract | Virginia Electric and Power Company
Derivative [Line Items]
Derivative payment | $	[2]	$ 250
Foreign Currency Exchange Rate - Current Derivative Contract
Derivative [Line Items]
Derivative payment	[2]		kr 468	€ 351
Foreign Currency Exchange Rate - Current Derivative Contract | Virginia Electric and Power Company
Derivative [Line Items]
Derivative payment	[2]		468	351
Fixed Price - Natural Gas - Non-current Derivative Contract
Derivative [Line Items]
Volume of derivative activity | Bcf	[1]	7
Fixed Price - Natural Gas - Non-current Derivative Contract | Virginia Electric and Power Company
Derivative [Line Items]
Volume of derivative activity | Bcf		7
Basis - Natural Gas - Non-current Derivative Contract
Derivative [Line Items]
Volume of derivative activity | Bcf	[1]	439
Basis - Natural Gas - Non-current Derivative Contract | Virginia Electric and Power Company
Derivative [Line Items]
Volume of derivative activity | Bcf	[1]	428
Fixed Price - Electricity - Non-current Derivative Contract
Derivative [Line Items]
Volume of electricity | MWh		31
Fixed Price - Electricity - Non-current Derivative Contract | Virginia Electric and Power Company
Derivative [Line Items]
Volume of electricity | MWh		5
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
Oil - Non-current Derivative Contract
Derivative [Line Items]
Derivative payment | $		$ 0
Oil - Non-current Derivative Contract | Virginia Electric and Power Company
Derivative [Line Items]
Derivative payment | $		0
Interest Rate - Non-current Derivative Contract
Derivative [Line Items]
Derivative payment | $	[2]	12,581
Interest Rate - Non-current Derivative Contract | Virginia Electric and Power Company
Derivative [Line Items]
Derivative payment | $	[2]	$ 3,050
Foreign Currency Exchange Rate - Non-current Derivative Contract
Derivative [Line Items]
Derivative payment	[2]		4,167	2,651
Foreign Currency Exchange Rate - Non-current Derivative Contract | Virginia Electric and Power Company
Derivative [Line Items]
Derivative payment	[2]		kr 4,167	€ 2,651

[1] Includes options.

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