Rate and Other Regulatory Matters (Narrative) (Detail) $ in Millions	1 Months Ended					6 Months Ended
	Jun. 30, 2025 USD ($)	Feb. 28, 2025 USD ($)	Jan. 31, 2025 USD ($)	Dec. 31, 2024 USD ($) mi kV	Sep. 30, 2024 USD ($)	Jun. 30, 2025	Feb. 27, 2025 USD ($)
Rate And Other Regulatory Matters [Line Items]
Miles of Lines | mi				17
Type of Line | kV				230
Estimated electric transmission project cost				$ 55
Regulatory asset recovery assessment end period						2078
Dominion Energy South Carolina, Inc. [Member]
Rate And Other Regulatory Matters [Line Items]
Storm restoration expected recovery period						2034
Storm restoration expected recovery					$ 2
Electric - Cost of Fuel [Member]
Rate And Other Regulatory Matters [Line Items]
Proposed South Carolina Commission Order for Increase of Total Fuel Cost Component of Retail Electric Rates to produce a projected under-recovery							$ 154
Natural Gas Rates [Member]
Rate And Other Regulatory Matters [Line Items]
Public utilities, total revenue requirement amount	$ 596
Amount of increase in base rate	$ 17
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						2039
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]
Deferred transmission operating costs expected recovery period						2062
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			$ 46
South Carolina Commission [Member] | Electric - Other [Member]
Rate And Other Regulatory Matters [Line Items]
Annual increase (decrease) in pension cost rider		$ 13