Rate and Other Regulatory Matters (Narrative) (Detail) - USD ($) $ in Millions	1 Months Ended					9 Months Ended
	Oct. 31, 2022	Jun. 30, 2022	Apr. 30, 2022	Jan. 31, 2022	Nov. 30, 2021	Sep. 30, 2022	Aug. 31, 2022
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				$ 399
Annual increase (decrease) in pension cost rider			(12)
South Carolina Commission order, revenue requirement under RSA		$ 553
South Carolina Commission order, increase in natural gas rates under RSA		129
South Carolina Commission order, increase in natural gas rates under RSA effective first billing cycle		$ 16
Percentage of current authorized earned ROE		8.14%			9.90%
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. [Member]
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
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
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						26 years
Subsequent Event [Member]
Rate And Other Regulatory Matters [Line Items]
South Carolina Commission order, revenue requirement under RSA	$ 549
South Carolina Commission order, increase in natural gas rates under RSA	125
South Carolina Commission order, increase in natural gas rates under RSA effective first billing cycle	$ 12
Rider D S M
Rate And Other Regulatory Matters [Line Items]
South Carolina Commission Order, Annual DSM Program Rate Rider Recovery Amount				$ 60
Toshiba [Member]
Rate And Other Regulatory Matters [Line Items]
Bankruptcy Claims, Amount of Claims Filed			$ 66