Rate and Other Regulatory Matters (Narrative) (Detail) $ in Millions	1 Months Ended							6 Months Ended	12 Months Ended
	Feb. 29, 2024 USD ($)	Jan. 31, 2024 USD ($)	Sep. 30, 2023 USD ($)	Apr. 30, 2023 USD ($)	Mar. 31, 2023 USD ($) mi	Jan. 31, 2023 USD ($)	Jul. 31, 2021 USD ($)	Jun. 30, 2021 USD ($)	Dec. 31, 2023 kV	Dec. 31, 2021 USD ($)	Feb. 28, 2023 USD ($)
Rate And Other Regulatory Matters [Line Items]
Regulatory asset recovery assessment end period									2078
Monetization Of Guaranty Settlement [Member]
Rate And Other Regulatory Matters [Line Items]
Electric service customers recovery period									20 years
End period for recovery									Dec. 31, 2039
Income Taxes Refundable Through Future Rates [Member]
Rate And Other Regulatory Matters [Line Items]
Remaining lives of related property period									85 years
Reserve For Refunds To Electric Utility Customers [Member]
Rate And Other Regulatory Matters [Line Items]
Electric service customers recovery period									11 years
Deferred Losses or Gains On Interest Rate Derivatives [Member]
Rate And Other Regulatory Matters [Line Items]
Changes in fair value and payments of interest rate derivatives designated as cash flow hedge, amortized to interest expense, year									2065
Dominion Energy South Carolina, Inc. [Member]
Rate And Other Regulatory Matters [Line Items]
Storm restoration recovery period									10 years
NND Project Costs [Member]
Rate And Other Regulatory Matters [Line Items]
Electric service customers recovery period									20 years
End period for recovery									Dec. 31, 2039
Deferred Employee Benefit Plan Costs [Member]
Rate And Other Regulatory Matters [Line Items]
Regulatory asset recovery assessment end period									2044
Average service period expected to recover other deferred benefit costs									11 years
Other Unrecovered Plant [Member]
Rate And Other Regulatory Matters [Line Items]
Amortization of carrying value of coal-fired generating unit									2025
New expected amortization of carrying value of coal-fired generating unit									2033
Advanced Metering Infrastructure Project [Member]
Rate And Other Regulatory Matters [Line Items]
New expected amortization of carrying value of coal-fired generating unit									2028
Demand Side Management Programs [Member]
Rate And Other Regulatory Matters [Line Items]
Recovery period of regulatory asset									3 years
Asset Retirement Obligation Costs [Member]
Rate And Other Regulatory Matters [Line Items]
Recovery period of regulatory asset									105 years
Environmental Remediation Costs [Member]
Rate And Other Regulatory Matters [Line Items]
Recovery period of regulatory asset									25 years
Deferred Transmission Operating Costs [Member]
Rate And Other Regulatory Matters [Line Items]
Recovery period of regulatory asset									42 years
Electric Base Rate Case [Member]
Rate And Other Regulatory Matters [Line Items]
Amount of Increase in proposed non fuel base rate							$ 62
Percentage of current authorized earned ROE							9.50%
Non fuel base rate increase after amortization							$ 36
Retail electric customer balance							15
Welfare charges for customers							$ 15
Other asset impairment charges								$ 249
Other asset impairment charges after tax								187
Purchase of first mortgage bond								$ 237
Recovery under settlement agreement										$ 18
Recovery under settlement agreement after tax										$ 14
Electric - Cost of Fuel [Member]
Rate And Other Regulatory Matters [Line Items]
Miles of Lines | mi					19
Type of Line | kV									230
Estimated electric transmission cost					$ 55
South Carolina Commission Order for Increase/Decrease of Total Fuel Cost Component of Retail Electric Rates to produce a projected under-recovery											$ 176
Natural Gas Rates [Member]
Rate And Other Regulatory Matters [Line Items]
Amount of increase in proposed base rate			$ 9		$ 19
Percentage of proposed ROE					10.38%
Percentage of currently authorized ROE			9.49%		10.25%
Rider DSM [Member] | Subsequent Event [Member]
Rate And Other Regulatory Matters [Line Items]
South Carolina Commission Order, Annual DSM Program Rate Rider Recovery Amount		$ 47
Rider DSM [Member] | Electric - Other [Member]
Rate And Other Regulatory Matters [Line Items]
South Carolina Commission Order, Annual DSM Program Rate Rider Recovery Amount						$ 46
South Carolina Commission [Member] | Electric - Cost of Fuel [Member]
Rate And Other Regulatory Matters [Line Items]
South Carolina Commission Order for Increase/Decrease of Total Fuel Cost Component of Retail Electric Rates to produce a projected under-recovery				$ 121
South Carolina Commission [Member] | Electric - Cost of Fuel [Member] | Subsequent Event [Member]
Rate And Other Regulatory Matters [Line Items]
South Carolina Commission Order for Increase/Decrease of Total Fuel Cost Component of Retail Electric Rates to produce a projected under-recovery	$ (315)
South Carolina Commission [Member] | Electric - Other [Member]
Rate And Other Regulatory Matters [Line Items]
Annual increase (decrease) in pension cost rider				$ 24
South Carolina Commission [Member] | Electric - Other [Member] | Subsequent Event [Member]
Rate And Other Regulatory Matters [Line Items]
Annual increase (decrease) in pension cost rider	$ 9