Commitments and Contingencies (Nuclear Operations) (Narrative) (Detail) - USD ($)	1 Months Ended		12 Months Ended
	Dec. 31, 2023	Sep. 30, 2023	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Loss Contingencies [Line Items]
Minimum financial assurance	$ 3,600,000,000		$ 3,600,000,000
NRC minimum requirement for nuclear power plant licensees	1,060,000,000.00		1,060,000,000.00
Maximum assessment for premiums on insurance policy			33,000,000
Maximum assessment for insurance policy			67,000,000
Receivables for spent nuclear fuel	62,000,000		62,000,000	$ 56,000,000
Maximum
Loss Contingencies [Line Items]
Amount that could be assessed for each licensed reactor	166,000,000		166,000,000
Amount that could be assessed for each licensed reactor per reactor	25,000,000		25,000,000
Nuclear Obligations
Loss Contingencies [Line Items]
Maximum liability protection per nuclear incident amount			16,200,000,000
Nuclear Obligations | Secondary Financial Protection Program
Loss Contingencies [Line Items]
Maximum liability protection per nuclear incident amount	16,200,000,000	$ 13,700,000,000
Virginia Electric and Power Company
Loss Contingencies [Line Items]
Minimum financial assurance	2,100,000,000		2,100,000,000
Maximum assessment for premiums on insurance policy			9,000,000
Maximum assessment for insurance policy			33,000,000
Receivables for spent nuclear fuel	43,000,000		43,000,000	37,000,000
DESC | Non-nuclear Obligation | European Mutual Association
Loss Contingencies [Line Items]
Property insurance coverage	1,000,000		1,000,000
Surry and North Anna
Loss Contingencies [Line Items]
Settlement amount awarded from other party			22,000,000	17,000,000	$ 25,000,000
Millstone
Loss Contingencies [Line Items]
Settlement amount awarded from other party			8,000,000	7,000,000	9,000,000
Summer
Loss Contingencies [Line Items]
Settlement amount awarded from other party			6,000,000	$ 1,000,000	$ 1,000,000
Millstone, Summer, Surry and North Anna
Loss Contingencies [Line Items]
Amount of coverage purchased from commercial insurance pools	450,000,000		450,000,000
Property insurance coverage	$ 1,060,000,000.00		$ 1,060,000,000.00