Fair Value Measurements (Financial Instruments' Carrying Amounts and Fair Values) (Detail) - USD ($) $ in Millions		Mar. 31, 2024	Dec. 31, 2023
Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	[1]	$ 36,529	$ 42,526
Supplemental credit facility borrowings		450	450
Securitization bonds	[2]	1,282
Junior subordinated notes	[1]	1,388	1,388
Estimate of Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	[1],[3]	34,197	40,539
Supplemental credit facility borrowings		450	450
Securitization bonds	[2],[3]	1,280
Junior subordinated notes	[1],[3]	1,389	1,374
Virginia Electric and Power Company | Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	[1]	18,032	17,392
Securitization bonds	[2]	1,282
Virginia Electric and Power Company | Estimate of Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	[1],[3]	16,665	$ 16,418
Securitization bonds	[2],[3]	$ 1,280

[1] Carrying amount includes current portions included in securities due within one year and amounts which represent the unamortized debt issuance costs and discount or premium. There were no fair value hedges associated with fixed-rate debt at March 31, 2024 and December 31, 2023. Additionally, Dominion Energy carrying amounts include portions classified as current liabilities held for sale at both March 31, 2024 and December 31, 2023.

[2] Carrying amount includes current portions included in securities due within one year.

[3] Fair value is estimated using market prices, where available, and interest rates currently available for issuance of debt with similar terms and remaining maturities. All fair value measurements are classified as Level 2. The carrying amount of debt issuances with short-term maturities and variable rates refinanced at current market rates is a reasonable estimate of their fair value.