Employee Benefit Plans (Narrative) (Detail) - USD ($)	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Accumulated benefit obligation			$ 7,400,000,000	$ 8,100,000,000
Defined contribution plan, employer matching contributions			82,000,000	85,000,000	$ 75,000,000
Defined contribution plan operating expenses within discontinued operations	$ 23,000,000
Defined contribution plan operating expenses within discontinued operations after tax	17,000,000
Defined contribution plan other operations and maintenance expense	13,000,000
Defined contribution plan other operations and maintenance expense after tax	$ 10,000,000
East Ohio and Questar Gas Transactions
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Remeasured pension and other postretirement benefit plans amount			217,000,000
Remeasured pension and other postretirement benefit plans after tax amount			162,000,000
Discontinued Operations
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost			5,000,000	18,000,000	25,000,000
Non-service cost			$ 12,000,000	(46,000,000)	(81,000,000)
U.S. Equity
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%
Virginia Electric and Power Company
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined contribution plan, employer matching contributions			$ 29,000,000	26,000,000	22,000,000
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			738,000,000	1,200,000,000
Expected return on pension and other postretirement plan assets			982,000,000	1,000,000,000
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			503,000,000	882,000,000
Expected return on pension and other postretirement plan assets			811,000,000	864,000,000	886,000,000
Increase to net periodic benefit cost (credit)			(426,000,000)	(22,000,000)	312,000,000
Actuarial gains (losses) from increase decrease in discount rate			404,000,000	322,000,000
Service cost			$ 83,000,000	96,000,000	142,000,000
Pension Benefits | Closure of East Ohio Transaction
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Remeasurement, discount rate			5.62%
Pension Benefits | Questar Gas Transactions
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Remeasurement, discount rate			5.75%
Pension Benefits | Forecast
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Expected contributions to qualified defined benefit pension plans in next fiscal year		$ 22,000,000
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
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)			$ 49,000,000	$ 34,000,000	72,000,000
Pension Benefits | Minimum
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Remeasurement, discount rate			5.84%	5.37%
Pension Benefits | Maximum
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Remeasurement, discount rate			5.87%	5.47%
Other Postretirement Benefits Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Actual return (loss) on pension and other postretirement plan assets			$ 235,000,000	$ 277,000,000
Expected return on pension and other postretirement plan assets			171,000,000	151,000,000	191,000,000
Increase to net periodic benefit cost (credit)			(250,000,000)	(237,000,000)	76,000,000
Actuarial gain (loss) by offset of decrease in discount rate from favorable claims and other				28,000,000
Actuarial gains (losses) from increase decrease in capital claims expense and other expense				1,000,000
Actuarial gains (losses) from increase decrease in discount rate			43,000,000	29,000,000
Contribution to voluntary employees beneficiary association						$ 0
Service cost			$ 11,000,000	14,000,000	22,000,000
Other Postretirement Benefits Plan | Questar Gas Transactions
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Remeasurement, discount rate			5.74%
Other Postretirement Benefits Plan | 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 Plan | 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 Plan | 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)			$ (72,000,000)	$ (60,000,000)	$ (81,000,000)
Other Postretirement Benefits Plan | Minimum
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Remeasurement, discount rate			5.83%	5.40%
Other Postretirement Benefits Plan | Minimum | Closure of East Ohio Transaction
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Remeasurement, discount rate			5.61%
Other Postretirement Benefits Plan | Maximum
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Remeasurement, discount rate			5.86%	5.42%
Other Postretirement Benefits Plan | Maximum | Closure of East Ohio Transaction
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Remeasurement, discount rate			5.62%
Revised Long-term Strategic Target Asset | Public equity
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined benefit plan, actual plan asset allocation percentages			30.00%
Revised Long-term Strategic Target Asset | Fixed Income Funds
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined benefit plan, actual plan asset allocation percentages			27.00%
Revised Long-term Strategic Target Asset | 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			43.00%