Derivatives and Hedge Accounting Activities (Schedule of Offsetting Liabilities) (Detail) - USD ($) $ in Millions		Sep. 30, 2024	Dec. 31, 2023
Offsetting Liabilities [Line Items]
Gross Liabilities Presented in the Consolidated Balance Sheet	[1]	$ 177	$ 697
Gross Amounts Not Offset in the Consolidated Balance Sheet, Financial Instruments		99	250
Gross Amounts Not Offset in the Consolidated Balance Sheet, Cash Collateral		0	30
Net Amounts		78	417
Virginia Electric and Power Company
Offsetting Liabilities [Line Items]
Gross Liabilities Presented in the Consolidated Balance Sheet	[1]	75	240
Gross Amounts Not Offset in the Consolidated Balance Sheet, Financial Instruments		25	27
Gross Amounts Not Offset in the Consolidated Balance Sheet, Cash Collateral		0	30
Net Amounts		50	183
Commodity Contract | Over-the-counter
Offsetting Liabilities [Line Items]
Gross Liabilities Presented in the Consolidated Balance Sheet	[1]	59	266
Gross Amounts Not Offset in the Consolidated Balance Sheet, Financial Instruments		28	26
Gross Amounts Not Offset in the Consolidated Balance Sheet, Cash Collateral		0	30
Net Amounts		31	210
Commodity Contract | Over-the-counter | Virginia Electric and Power Company
Offsetting Liabilities [Line Items]
Gross Liabilities Presented in the Consolidated Balance Sheet	[1]	21	153
Gross Amounts Not Offset in the Consolidated Balance Sheet, Financial Instruments		15	13
Gross Amounts Not Offset in the Consolidated Balance Sheet, Cash Collateral		0	30
Net Amounts		6	110
Commodity Contract | Exchange
Offsetting Liabilities [Line Items]
Gross Liabilities Presented in the Consolidated Balance Sheet	[1]	46	33
Gross Amounts Not Offset in the Consolidated Balance Sheet, Financial Instruments		46	33
Gross Amounts Not Offset in the Consolidated Balance Sheet, Cash Collateral		0	0
Net Amounts		0	0
Commodity Contract | Exchange | Virginia Electric and Power Company
Offsetting Liabilities [Line Items]
Gross Liabilities Presented in the Consolidated Balance Sheet	[1]	2	3
Gross Amounts Not Offset in the Consolidated Balance Sheet, Financial Instruments		2	3
Gross Amounts Not Offset in the Consolidated Balance Sheet, Cash Collateral		0	0
Net Amounts		0	0
Interest Rate Contract | Over-the-counter
Offsetting Liabilities [Line Items]
Gross Liabilities Presented in the Consolidated Balance Sheet	[1]	20	359
Gross Amounts Not Offset in the Consolidated Balance Sheet, Financial Instruments		17	186
Gross Amounts Not Offset in the Consolidated Balance Sheet, Cash Collateral		0	0
Net Amounts		3	173
Interest Rate Contract | Over-the-counter | Virginia Electric and Power Company
Offsetting Liabilities [Line Items]
Gross Liabilities Presented in the Consolidated Balance Sheet	[1]	0	45
Gross Amounts Not Offset in the Consolidated Balance Sheet, Financial Instruments		0	6
Gross Amounts Not Offset in the Consolidated Balance Sheet, Cash Collateral		0	0
Net Amounts		0	39
Foreign currency exchange rate | Over-the-counter
Offsetting Liabilities [Line Items]
Gross Liabilities Presented in the Consolidated Balance Sheet	[1]	52	39
Gross Amounts Not Offset in the Consolidated Balance Sheet, Financial Instruments		8	5
Gross Amounts Not Offset in the Consolidated Balance Sheet, Cash Collateral		0	0
Net Amounts		44	34
Foreign currency exchange rate | Over-the-counter | Virginia Electric and Power Company
Offsetting Liabilities [Line Items]
Gross Liabilities Presented in the Consolidated Balance Sheet	[1]	52	39
Gross Amounts Not Offset in the Consolidated Balance Sheet, Financial Instruments		8	5
Gross Amounts Not Offset in the Consolidated Balance Sheet, Cash Collateral		0	0
Net Amounts		$ 44	$ 34

[1] Excludes derivative liabilities of $4 million at Dominion Energy at September 30, 2024 and $37 million and $76 million at Virginia Power at September 30, 2024 and December 31, 2023, respectively, which are not subject to master netting or similar arrangements. Dominion Energy did not have any derivative liabilities at December 31, 2023 which were not subject to master netting or similar arrangements.