Commitments and Contingencies (Claims and Litigation) (Narrative) (Detail) - USD ($)	1 Months Ended														3 Months Ended	12 Months Ended
	Jul. 31, 2023	Jun. 30, 2023	Sep. 30, 2022	Jun. 30, 2022	May 31, 2022	Dec. 31, 2021	Aug. 31, 2021	Jul. 31, 2021	Jun. 30, 2021	Dec. 31, 2020	Sep. 30, 2020	Aug. 31, 2020	Jul. 31, 2019	Jun. 30, 2018	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2018
Loss Contingencies [Line Items]
Reserves for litigation and regulatory proceedings																$ 3,000,000	$ 94,000,000
Insurance receivables																	68,000,000
Impairment of assets and other charges																3,000,000	4,000,000	$ 311,000,000
Settlement payable by company								$ 99,000,000
Proportionate ownership share in project														100.00%
Proposed assessment amount from SCDOR audit														$ 410,000,000
Litigation settlement expense awarded										$ 165,000,000
Real estate transfer to satisfy obligation under settlement				$ 51,000,000
SCDOR
Loss Contingencies [Line Items]
Value of certain utility and non-utility properties to be conveyed																	3,000,000
Non utility property fair value			$ 28,000,000
Fair value of certain utility property transferred															$ 10,000,000
Fair value of certain remaining utility property transferred		$ 11,000,000
DESC Ratepayer Case
Loss Contingencies [Line Items]
Property with net value transferred						$ 8,000,000						$ 22,000,000
Conveyance of property with net recorded value											$ 3,000,000
Property with net value transferred, cash contribution											$ 38,500,000
Cash payment													$ 117,000,000						$ 115,000,000
Escrow account																			2,000,000,000
Credit in future electric rate relief																			2,000,000,000
Common Stock | Dominion Energy
Loss Contingencies [Line Items]
Litigation settlement through cash									$ 43,000,000
Litigation settlement through stock issuance					900,000		600,000	1,400,000
Impairment of Assets and Other Charges | Dominion Energy South Carolina, Inc.
Loss Contingencies [Line Items]
Impairment of assets and other charges																		70,000,000
Impairment of assets and other charges, after-tax																		$ 53,000,000
Other Income (Expense), Net | SCDOR
Loss Contingencies [Line Items]
Gain from transferred utility property																9,000,000
Gain from transferred utility property after-tax																7,000,000
Gain from transferred non utility property																	19,000,000
Gain from transferred non utility property, after tax																	14,000,000
Gain from transferred remaining utility property																11,000,000
Gain from transferred remaining utility property, after tax																$ 8,000,000
Personal Injury or Wrongful Death Cases
Loss Contingencies [Line Items]
Reserves for litigation and regulatory proceedings																	$ 68,000,000
Minimum [Member] | DESC Ratepayer Case
Loss Contingencies [Line Items]
Proceeds from sale of property																			60,000,000
Maximum [Member] | SCDOR
Loss Contingencies [Line Items]
Cash payment	$ 1,000,000
Maximum [Member] | DESC Ratepayer Case
Loss Contingencies [Line Items]
Proceeds from sale of property																			$ 85,000,000