Income Taxes (Schedule of Deductible Loss and Credit Carryforwards) (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2023 USD ($)
Deductible loss and credit carryforwards [Line Items]
Deductible amount	$ 3,254
Losses, Deferred tax asset	1,059
Losses, Valuation allowance	(130)
Virginia Electric and Power Company
Deductible loss and credit carryforwards [Line Items]
Deductible amount	3
Losses, Deferred tax asset	308
Losses, Valuation allowance	(8)
Federal
Deductible loss and credit carryforwards [Line Items]
Deductible amount	576
Losses, Deferred tax asset	$ 121
Losses, Expiration Period	2037
Federal | Investment Credits
Deductible loss and credit carryforwards [Line Items]
Tax credits, Deferred tax asset	$ 264
Federal | Investment Credits | Virginia Electric and Power Company
Deductible loss and credit carryforwards [Line Items]
Tax credits, Deferred tax asset	$ 241
Federal | Investment Credits | Earliest Tax Year
Deductible loss and credit carryforwards [Line Items]
Tax Credits, Expiration Period	2041
Federal | Investment Credits | Earliest Tax Year | Virginia Electric and Power Company
Deductible loss and credit carryforwards [Line Items]
Tax Credits, Expiration Period	2041
Federal | Investment Credits | Latest Tax Year
Deductible loss and credit carryforwards [Line Items]
Tax Credits, Expiration Period	2043
Federal | Investment Credits | Latest Tax Year | Virginia Electric and Power Company
Deductible loss and credit carryforwards [Line Items]
Tax Credits, Expiration Period	2043
Federal | Federal Production and Other Credits
Deductible loss and credit carryforwards [Line Items]
Tax credits, Deferred tax asset	$ 91
Federal | Federal Production and Other Credits | Virginia Electric and Power Company
Deductible loss and credit carryforwards [Line Items]
Tax credits, Deferred tax asset	$ 58
Federal | Federal Production and Other Credits | Earliest Tax Year
Deductible loss and credit carryforwards [Line Items]
Tax Credits, Expiration Period	2041
Federal | Federal Production and Other Credits | Earliest Tax Year | Virginia Electric and Power Company
Deductible loss and credit carryforwards [Line Items]
Tax Credits, Expiration Period	2041
Federal | Federal Production and Other Credits | Latest Tax Year
Deductible loss and credit carryforwards [Line Items]
Tax Credits, Expiration Period	2043
Federal | Federal Production and Other Credits | Latest Tax Year | Virginia Electric and Power Company
Deductible loss and credit carryforwards [Line Items]
Tax Credits, Expiration Period	2043
State
Deductible loss and credit carryforwards [Line Items]
Deductible amount	$ 2,678
Losses, Deferred tax asset	131
Losses, Valuation allowance	(51)
State minimum tax credits	327
State | Virginia Electric and Power Company
Deductible loss and credit carryforwards [Line Items]
Deductible amount	$ 3
Losses, Expiration Period	2042
State | Earliest Tax Year
Deductible loss and credit carryforwards [Line Items]
Losses, Expiration Period	2024
State | Latest Tax Year
Deductible loss and credit carryforwards [Line Items]
Losses, Expiration Period	2043
State | Investment and Other Credits
Deductible loss and credit carryforwards [Line Items]
Losses, Valuation allowance	$ (79)
Tax credits, Deferred tax asset	125
State | Investment and Other Credits | Virginia Electric and Power Company
Deductible loss and credit carryforwards [Line Items]
Losses, Valuation allowance	(8)
Tax credits, Deferred tax asset	$ 9
Tax Credits, Expiration Period	2024
State | Investment and Other Credits | Earliest Tax Year
Deductible loss and credit carryforwards [Line Items]
Tax Credits, Expiration Period	2024
State | Investment and Other Credits | Latest Tax Year
Deductible loss and credit carryforwards [Line Items]
Tax Credits, Expiration Period	2033