Rate and Other Regulatory Matters (Narrative) (Detail) - USD ($) $ in Millions	1 Months Ended		3 Months Ended
	Apr. 30, 2022	Jan. 31, 2022	Mar. 31, 2022
Rate And Other Regulatory Matters [Line Items]
Regulatory asset recovery assessment end period			2047
Reserve For Refunds To Electric Utility Customers [Member]
Rate And Other Regulatory Matters [Line Items]
Electric service customers recovery period			11 years
Dominion Energy South Carolina, Inc.
Rate And Other Regulatory Matters [Line Items]
Storm restoration recovery period			10 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			2043
Changes in fair value and payments of interest rate derivatives not designed, amortized to interest, 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			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			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			2029
Increase in abandonment of certain peaking gas generation facilities			$ 7
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
Cost of Fuel and Purchased Gas Under-Collections [Member] | Cost of Fuel and Purchased Gas Over-Collections [Member]
Rate And Other Regulatory Matters [Line Items]
Decrease in fuel costs			$ 66
Environmental Remediation Costs [Member]
Rate And Other Regulatory Matters [Line Items]
Recovery period of regulatory asset			27 years
Rider D S M
Rate And Other Regulatory Matters [Line Items]
South Carolina Commission Order, Annual DSM Program Rate Rider Recovery Amount		$ 60
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	$ 143
Annual increase (decrease) in pension cost rider	(12)
Toshiba [Member] | Subsequent Event [Member]
Rate And Other Regulatory Matters [Line Items]
Bankruptcy Claims, Amount of Claims Filed	$ 66