Derivatives and Hedge Accounting Activities (Schedule of Offsetting Liabilities) (Detail) - USD ($) $ in Millions		Mar. 31, 2025	Dec. 31, 2024
Offsetting Liabilities [Line Items]
Gross Liabilities Presented in the Consolidated Balance Sheet	[1]	$ 465	$ 505
Gross Amounts Not Offset in the Consolidated Balance Sheet, Financial Instruments		277	301
Gross Amounts Not Offset in the Consolidated Balance Sheet, Cash Collateral		14	20
Net Amounts		174	184
Virginia Electric and Power Company
Offsetting Liabilities [Line Items]
Gross Liabilities Presented in the Consolidated Balance Sheet	[1]	180	208
Gross Amounts Not Offset in the Consolidated Balance Sheet, Financial Instruments		18	45
Gross Amounts Not Offset in the Consolidated Balance Sheet, Cash Collateral		1	0
Net Amounts		161	163
Commodity Contract | Over-the-counter
Offsetting Liabilities [Line Items]
Gross Liabilities Presented in the Consolidated Balance Sheet	[1]	44	42
Gross Amounts Not Offset in the Consolidated Balance Sheet, Financial Instruments		8	20
Gross Amounts Not Offset in the Consolidated Balance Sheet, Cash Collateral		0	0
Net Amounts		36	22
Commodity Contract | Over-the-counter | Virginia Electric and Power Company
Offsetting Liabilities [Line Items]
Gross Liabilities Presented in the Consolidated Balance Sheet	[1]	40	15
Gross Amounts Not Offset in the Consolidated Balance Sheet, Financial Instruments		7	14
Gross Amounts Not Offset in the Consolidated Balance Sheet, Cash Collateral		0	0
Net Amounts		33	1
Commodity Contract | Exchange
Offsetting Liabilities [Line Items]
Gross Liabilities Presented in the Consolidated Balance Sheet	[1]	96	74
Gross Amounts Not Offset in the Consolidated Balance Sheet, Financial Instruments		82	54
Gross Amounts Not Offset in the Consolidated Balance Sheet, Cash Collateral		14	20
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	1
Gross Amounts Not Offset in the Consolidated Balance Sheet, Financial Instruments		1	1
Gross Amounts Not Offset in the Consolidated Balance Sheet, Cash Collateral		1	0
Net Amounts		0	0
Interest Rate Contract | Over-the-counter
Offsetting Liabilities [Line Items]
Gross Liabilities Presented in the Consolidated Balance Sheet	[1]	204	197
Gross Amounts Not Offset in the Consolidated Balance Sheet, Financial Instruments		178	197
Gross Amounts Not Offset in the Consolidated Balance Sheet, Cash Collateral		0	0
Net Amounts		26	0
Interest Rate Contract | Over-the-counter | Virginia Electric and Power Company
Offsetting Liabilities [Line Items]
Gross Liabilities Presented in the Consolidated Balance Sheet	[1]	17	0
Gross Amounts Not Offset in the Consolidated Balance Sheet, Financial Instruments		1	0
Gross Amounts Not Offset in the Consolidated Balance Sheet, Cash Collateral		0	0
Net Amounts		16	0
Foreign Currency Exchange Rate Contract | Over-the-counter
Offsetting Liabilities [Line Items]
Gross Liabilities Presented in the Consolidated Balance Sheet	[1]	121	192
Gross Amounts Not Offset in the Consolidated Balance Sheet, Financial Instruments		9	30
Gross Amounts Not Offset in the Consolidated Balance Sheet, Cash Collateral		0	0
Net Amounts		112	162
Foreign Currency Exchange Rate Contract | Over-the-counter | Virginia Electric and Power Company
Offsetting Liabilities [Line Items]
Gross Liabilities Presented in the Consolidated Balance Sheet	[1]	121	192
Gross Amounts Not Offset in the Consolidated Balance Sheet, Financial Instruments		9	30
Gross Amounts Not Offset in the Consolidated Balance Sheet, Cash Collateral		0	0
Net Amounts		$ 112	$ 162

[1] Excludes derivative liabilities of $10 million and $7 million at Dominion Energy and $3 million and $17 million at Virginia Power at March 31, 2025 and December 31, 2024, respectively, which are not subject to master netting or similar arrangements.