Employee Benefit Plans (Narrative) (Detail) - USD ($)		1 Months Ended		3 Months Ended	12 Months Ended
		Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2021	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Accumulated benefit obligation		$ 10,200,000,000		$ 10,200,000,000		$ 7,700,000,000	$ 10,200,000,000
Defined contribution plan, employer matching contributions						$ 75,000,000	65,000,000	$ 67,000,000
Discontinued Operations
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost							1,000,000	13,000,000
Common and Preferred Stocks
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined benefit plan, actual plan asset allocation percentages						26.00%
Non-U.S. Equity
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined benefit plan, actual plan asset allocation percentages						19.00%
Fixed Income Funds
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined benefit plan, actual plan asset allocation percentages						32.00%
Real Assets
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined benefit plan, actual plan asset allocation percentages						3.00%
Other than Securities Investment
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined benefit plan, actual plan asset allocation percentages						20.00%
Series C Preferred Stock
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Issued to qualified defined benefit pension plans, shares		250,000
Virginia Electric and Power Company
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Amounts due to Dominion		$ 121,000,000		121,000,000		$ 255,000,000	121,000,000
Defined contribution plan, employer matching contributions						22,000,000	20,000,000	19,000,000
Pension Plans and Post Retirement Benefit Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Actual return (loss) on pension and other postretirement plan assets						3,000,000,000.0	1,500,000,000
Expected return on pension and other postretirement plan assets						1,100,000,000	1,000,000,000.0
Curtailment resulted in a decrease in the pension benefit obligation				26,000,000
Increase to net periodic benefit cost (credit)				$ 2,000,000
Pension Benefits
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Actual return (loss) on pension and other postretirement plan assets						(2,556,000,000)	1,202,000,000
Expected return on pension and other postretirement plan assets						886,000,000	834,000,000	777,000,000
Increase to net periodic benefit cost (credit)						(252,000,000)	(144,000,000)	(32,000,000)
Actuarial gains (losses) from increase decrease in discount rate						2,700,000,000	413,000,000
Contributions to qualified defined benefit pension plans			$ 250,000,000			9,000,000	284,000,000
Service cost						142,000,000	170,000,000	173,000,000
Pension Benefits | Series C Preferred Stock
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Contributions to qualified defined benefit pension plans		$ 250,000,000
Pension Benefits | Virginia Electric and Power Company | Amounts Associated With Dominion Pension Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Payment made to Dominion						172,000,000	151,000,000	313,000,000
Pension Benefits | Virginia Electric and Power Company | Other Operations and Maintenance
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Increase to net periodic benefit cost (credit)						72,000,000	86,000,000	118,000,000
Other Postretirement Benefits
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Actual return (loss) on pension and other postretirement plan assets						(416,000,000)	294,000,000
Expected return on pension and other postretirement plan assets						191,000,000	173,000,000	156,000,000
Increase to net periodic benefit cost (credit)						$ (172,000,000)	$ (140,000,000)	$ (172,000,000)
Health care cost trend decreased rate	[1]	5.00%	5.00%	5.00%		5.00%	5.00%	5.00%
Actuarial gains (losses) from increase decrease in discount rate						$ 360,000,000	$ 161,000,000
Contribution to voluntary employees beneficiary association							0
Service cost						22,000,000	25,000,000	$ 28,000,000
Other Postretirement Benefits | Virginia Electric and Power Company
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Contribution to voluntary employees beneficiary association						0	0	0
Other Postretirement Benefits | Virginia Electric and Power Company | Forecast
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Contribution to voluntary employees beneficiary association					$ 0
Other Postretirement Benefits | Virginia Electric and Power Company | Other Operations and Maintenance | Dominion Energy Retiree Health And Welfare Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Increase to net periodic benefit cost (credit)						$ (81,000,000)	$ (72,000,000)	$ (58,000,000)

[1] Assumptions used to determine net periodic cost for the following year.