Equity (Narrative) (Detail) - USD ($)	1 Months Ended										3 Months Ended	12 Months Ended
	Jul. 31, 2023	Apr. 30, 2023	Dec. 31, 2022	Jun. 30, 2022	May 31, 2022	Dec. 31, 2021	Nov. 30, 2021	Aug. 31, 2021	Jul. 31, 2021	Aug. 31, 2020	Dec. 31, 2023	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Nov. 30, 2020
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Issuance of common stock												$ 94,000,000	$ 1,866,000,000	$ 192,000,000
Issuance of stock to Dominion Energy												94,000,000	1,969,000,000	1,332,000,000
Compensation cost related to stock-based compensation												44,000,000	36,000,000	42,000,000
Tax benefit from stock awards and stock options exercised												$ 10,000,000	7,000,000	9,000,000
Vesting period												3 years
Cash Based Performance Grant | Officer
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Cash-based performance grants minimum percentage												0.00%
Cash-based performance grants maximum percentage												200.00%
February 2020 Cash Based Performance Grant | Officer | Grant Date Three
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Targeted amount of the grant			$ 4,000,000								$ 4,000,000	$ 4,000,000	4,000,000
February 2022 Cash Based Performance Grant | Officer | Grant Date Three
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Targeted amount of the grant											16,000,000	16,000,000
Liability accrued for award											5,000,000	5,000,000
February 2023 Cash Based Performance Grant | Officer | Grant Date Three
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Targeted amount of the grant											16,000,000	16,000,000
Liability accrued for award											$ 3,000,000	$ 3,000,000
Stock Based Awards
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares were available for future grants											15,000,000	15,000,000
Restricted Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized compensation cost related to nonvested awards											$ 70,000,000	$ 70,000,000
Fair value of restricted stock awards that vested												$ 20,000,000	$ 31,000,000	$ 37,000,000
S B L Holdco L L C | Nonregulated Solar Projects
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Controlling interest sold						67.00%
Four Brothers And Three Cedars
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Controlling interest sold						50.00%
Maximum | Stock Based Awards
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Maximum term of stock based awards												8 years
Weighted Average | Restricted Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected weighted-average period recognized for the unrecognized compensation cost												2 years 2 months 12 days
Common Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Issuance of stock (in shares)				400,000	900,000			600,000	1,400,000			2,000,000	25,000,000	4,000,000
Issuance of stock to Dominion Energy				$ 30,000,000	$ 72,000,000			$ 45,000,000	$ 104,000,000			$ 94,000,000	$ 1,969,000,000	$ 340,000,000
Stock repurchased, shares												0	0	0
Stock repurchase program, authorized amount											900,000,000	$ 900,000,000			$ 1,000,000,000
2019 Series A Corporate Units | Common Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Issuance of common stock				$ 1,600,000,000
Issuance of stock (in shares)				19,400,000
Dominion Energy Direct
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Issuance of common stock												$ 94,000,000	$ 179,000,000	$ 192,000,000
Issuance of stock (in shares)												1,700,000	2,400,000	2,600,000
Virginia Electric and Power Company
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Issuance of common stock											$ 3,250,000,000	$ 3,250,000,000
Issuance of stock (in shares)												0	0	0
Issuance of stock to Dominion Energy												$ 3,250,000,000
Virginia Electric and Power Company | Virginia Regulation
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Capitalization ratio	52.10%	52.10%									52.10%
Virginia Electric and Power Company | Common Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Issuance of stock (in shares)											49,522	49,000
Issuance of stock to Dominion Energy												$ 3,250,000,000
Various Programs
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Issuance of common stock												$ 94,000,000	$ 2,000,000,000	$ 340,000,000
Issuance of stock (in shares)												2,000,000	25,000,000	4,000,000
Sales Agency Agreements to Effect Sales Under At-the-market Program | Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Sale of stock authorized amount										$ 1,000,000,000
Forward Sale Agreements
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Issuance of common stock			$ 78,000,000
Forward sale agreements, number of shares of common stock to be settled							1,100,000
Initial forward price of share							$ 74.66