Rate and Other Regulatory Matters (Narrative) (Detail) $ in Millions	1 Months Ended			3 Months Ended
	Mar. 31, 2024 USD ($) mi kV	Feb. 29, 2024 USD ($)	Jan. 31, 2024 USD ($)	Mar. 31, 2024 USD ($)
Rate And Other Regulatory Matters [Line Items]
Miles of Lines | mi	7
Type of Line | kV	230
Estimated electric transmission project cost	$ 40
Regulatory asset recovery assessment end period				2078
Dominion Energy South Carolina, Inc. [Member]
Rate And Other Regulatory Matters [Line Items]
Storm restoration recovery period				10 years
Electric Base Rate Case [Member]
Rate And Other Regulatory Matters [Line Items]
Amount of Increase in proposed non fuel base rate	295
Decrease in storm damage and DSM components	4
Increase in proposed base rate amount	$ 291
Increase in proposed base rate percentage	12.59%
Percentage of current authorized earned ROE	9.50%
Percentage of earned return on equity	4.32%
Percentage of earned return on equity proposed rate	0.60%
Electric - Cost of Fuel [Member]
Rate And Other Regulatory Matters [Line Items]
Proposed South Carolina Commission Order for Decrease of Total Fuel Cost Component of Retail Electric Rates to produce a projected under-recovery		$ 315
South Carolina Commission Order for Increase/Decrease of Total Fuel Cost Component of Retail Electric Rates to produce a projected under-recovery	$ 316			$ 316
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
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
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			3 years
Asset Retirement Obligation Costs [Member]
Rate And Other Regulatory Matters [Line Items]
Recovery period of regulatory asset	105 years			105 years
Environmental Remediation Costs [Member]
Rate And Other Regulatory Matters [Line Items]
Recovery period of regulatory asset	24 years			24 years
Deferred Transmission Operating Costs [Member]
Rate And Other Regulatory Matters [Line Items]
Recovery period of regulatory asset	42 years			42 years
Rider D S M [Member] | Electric - Other [Member]
Rate And Other Regulatory Matters [Line Items]
South Carolina Commission Order, Annual DSM Program Rate Rider Recovery Amount			$ 47
South Carolina Commission [Member] | Electric - Other [Member]
Rate And Other Regulatory Matters [Line Items]
Annual increase (decrease) in pension cost rider		$ 9