Derivatives and Hedge Accounting Activities (Schedule of Offsetting Assets) (Detail) - USD ($) $ in Millions		Sep. 30, 2023	Dec. 31, 2022
Offsetting Assets [Line Items]
Gross Assets Presented in the Consolidated Balance Sheet	[1]	$ 1,509	$ 1,975
Gross Amounts Not Offset in the Consolidated Balance Sheet, Financial Instruments		437	435
Gross Amounts Not Offset in the Consolidated Balance Sheet, Cash Collateral Received		0	0
Net Amounts		1,072	1,540
Virginia Electric and Power Company
Offsetting Assets [Line Items]
Gross Assets Presented in the Consolidated Balance Sheet	[1]	472	852
Gross Amounts Not Offset in the Consolidated Balance Sheet, Financial Instruments		103	45
Gross Amounts Not Offset in the Consolidated Balance Sheet, Cash Collateral Received		0	0
Net Amounts		369	807
Commodity Contract | Over-the-counter
Offsetting Assets [Line Items]
Gross Assets Presented in the Consolidated Balance Sheet	[1]	152	408
Gross Amounts Not Offset in the Consolidated Balance Sheet, Financial Instruments		60	28
Gross Amounts Not Offset in the Consolidated Balance Sheet, Cash Collateral Received		0	0
Net Amounts		92	380
Commodity Contract | Over-the-counter | Virginia Electric and Power Company
Offsetting Assets [Line Items]
Gross Assets Presented in the Consolidated Balance Sheet	[1]	71	238
Gross Amounts Not Offset in the Consolidated Balance Sheet, Financial Instruments		37	7
Gross Amounts Not Offset in the Consolidated Balance Sheet, Cash Collateral Received		0	0
Net Amounts		34	231
Commodity Contract | Exchange
Offsetting Assets [Line Items]
Gross Assets Presented in the Consolidated Balance Sheet	[1]	47	160
Gross Amounts Not Offset in the Consolidated Balance Sheet, Financial Instruments		46	159
Gross Amounts Not Offset in the Consolidated Balance Sheet, Cash Collateral Received		0	0
Net Amounts		1	1
Commodity Contract | Exchange | Virginia Electric and Power Company
Offsetting Assets [Line Items]
Gross Assets Presented in the Consolidated Balance Sheet	[1]	3	0
Gross Amounts Not Offset in the Consolidated Balance Sheet, Financial Instruments		3	0
Gross Amounts Not Offset in the Consolidated Balance Sheet, Cash Collateral Received		0	0
Net Amounts		0	0
Interest Rate Contract | Over-the-counter
Offsetting Assets [Line Items]
Gross Assets Presented in the Consolidated Balance Sheet	[1]	1,301	1,407
Gross Amounts Not Offset in the Consolidated Balance Sheet, Financial Instruments		322	248
Gross Amounts Not Offset in the Consolidated Balance Sheet, Cash Collateral Received		0	0
Net Amounts		979	1,159
Interest Rate Contract | Over-the-counter | Virginia Electric and Power Company
Offsetting Assets [Line Items]
Gross Assets Presented in the Consolidated Balance Sheet	[1]	389	614
Gross Amounts Not Offset in the Consolidated Balance Sheet, Financial Instruments		54	38
Gross Amounts Not Offset in the Consolidated Balance Sheet, Cash Collateral Received		0	0
Net Amounts		335	$ 576
Foreign currency exchange rate | Over-the-counter
Offsetting Assets [Line Items]
Gross Assets Presented in the Consolidated Balance Sheet	[1]	9
Gross Amounts Not Offset in the Consolidated Balance Sheet, Financial Instruments		9
Gross Amounts Not Offset in the Consolidated Balance Sheet, Cash Collateral Received		0
Net Amounts		0
Foreign currency exchange rate | Over-the-counter | Virginia Electric and Power Company
Offsetting Assets [Line Items]
Gross Assets Presented in the Consolidated Balance Sheet	[1]	9
Gross Amounts Not Offset in the Consolidated Balance Sheet, Financial Instruments		9
Gross Amounts Not Offset in the Consolidated Balance Sheet, Cash Collateral Received		0
Net Amounts		$ 0

[1] Excludes derivative assets of $137 million and $201 million at Dominion Energy and $2 million and $30 million at Virginia Power at September 30, 2023 and December 31, 2022, respectively, which are not subject to master netting or other similar arrangements.