Employee Benefit Plans (Narrative) (Detail) - USD ($) shares in Millions		1 Months Ended		3 Months Ended				12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2020	Sep. 30, 2020	Sep. 30, 2019	Jun. 30, 2019	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Accumulated benefit obligation		$ 10,600,000,000	$ 9,700,000,000	$ 10,600,000,000					$ 10,600,000,000	$ 9,700,000,000
Contributions to qualified defined benefit pension plans										$ 499,000,000
Contributions to qualified defined benefit pension plans, shares										6.1
Contributions to qualified defined benefit pension plans in 2021		$ 17,000,000		$ 17,000,000					17,000,000
Defined contribution plan, employer matching contributions									67,000,000	$ 69,000,000	$ 46,000,000
Discontinued Operations
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost									$ 13,000,000	16,000,000	18,000,000
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		28.00%		28.00%					28.00%
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		18.00%		18.00%					18.00%
Fixed Income Funds
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined benefit plan, actual plan asset allocation percentages		35.00%		35.00%					35.00%
Real Estate Funds
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined benefit plan, actual plan asset allocation percentages		3.00%		3.00%					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		16.00%		16.00%					16.00%
Common Stock
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Contributions to qualified defined benefit pension plans										499,000,000
Virginia Electric and Power Company
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Amounts due to Dominion		$ 266,000,000	210,000,000	$ 266,000,000					$ 266,000,000	210,000,000
Defined contribution plan, employer matching contributions									19,000,000	20,000,000	20,000,000
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									1,900,000,000	2,100,000,000
Expected return on pension and other postretirement plan assets									933,000,000	848,000,000
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									1,602,000,000	1,747,000,000
Expected return on pension and other postretirement plan assets									777,000,000	708,000,000	663,000,000
Increase (decrease) in fair value of plan assets						$ 51,000,000	$ 671,000,000
Net periodic benefit cost (credit)									(32,000,000)	93,000,000	25,000,000
Actuarial losses from decrease in discount rate									(1,000,000,000.0)	(1,100,000,000)
Contributions to qualified defined benefit pension plans		250,000,000	$ 520,000,000						278,000,000	557,000,000
Service cost									173,000,000	162,000,000	157,000,000
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									313,000,000
Amounts due to Dominion		$ 151,000,000		$ 151,000,000					151,000,000
Pension Benefits | Virginia Electric and Power Company | Other Operations and Maintenance
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Net periodic benefit cost (credit)									$ 118,000,000	$ 152,000,000	126,000,000
Pension Benefits | Minimum
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Discount rate percentage		2.73%	3.47%	2.73%			4.07%		2.73%	3.47%
Pension Benefits | Maximum
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Discount rate percentage		2.95%	3.63%	2.95%			4.10%		2.95%	3.63%
Pension Benefits | BHE
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Remeasurement resulted in increase in pension benefit obligation					$ 497,000,000
Increase (decrease) in fair value of plan assets					$ (87,000,000)
Net periodic benefit cost (credit)									$ (4,000,000)
Pension Benefits | BHE | Minimum
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Discount rate percentage		3.11%		3.11%					3.11%
Pension Benefits | BHE | Maximum
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Discount rate percentage		3.16%		3.16%					3.16%
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									$ 300,000,000	$ 349,000,000
Expected return on pension and other postretirement plan assets									156,000,000	140,000,000	143,000,000
Increase (decrease) in fair value of plan assets							$ 156,000,000
Net periodic benefit cost (credit)									$ (172,000,000)	$ (46,000,000)	$ (101,000,000)
Health care cost trend rate	[1]	6.25%		6.25%					6.25%		7.00%
Health care cost trend decreased rate	[1]	5.00%	5.00%	5.00%					5.00%	5.00%	5.00%
Actuarial losses from decrease in discount rate									$ (149,000,000)	$ (168,000,000)
Actuarial gain from completed experience study and update to healthcare claim assumptions									85,000,000	55,000,000
Contributions to qualified defined benefit pension plans									13,000,000	12,000,000
Contribution to voluntary employees beneficiary association									0
Service cost									28,000,000	26,000,000	$ 27,000,000
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
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]
Net periodic benefit cost (credit)									$ (58,000,000)	$ (27,000,000)	$ (51,000,000)
Other Postretirement Benefits | Minimum
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Discount rate percentage		2.69%	3.44%	2.69%			4.05%		2.69%	3.44%
Health care cost trend rate	[1]		6.50%							6.50%
Other Postretirement Benefits | Maximum
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Discount rate percentage		2.80%	3.52%	2.80%			4.08%		2.80%	3.52%
Health care cost trend rate	[1]		6.60%							6.60%
Other Postretirement Benefits | BHE
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Increase (decrease) in fair value of plan assets				$ (25,000,000)
Increase in accumulated postretirement benefit obligation				$ 16,000,000
Health care cost trend rate		6.25%		6.25%					6.25%
Health care cost trend decreased rate		5.00%		5.00%					5.00%
Other Postretirement Benefits | BHE | Minimum
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Discount rate percentage		3.07%		3.07%					3.07%
Other Postretirement Benefits | BHE | Maximum
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Discount rate percentage		3.11%		3.11%					3.11%
Voluntary Retirement Program
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Remeasurement resulted in increase in pension benefit obligation						$ 37,000,000	$ 484,000,000
Discount rate percentage						3.57%
Increase in accumulated postretirement benefit obligation							$ 101,000,000
Voluntary retirement program related charges										$ 427,000,000
Voluntary retirement program related charges net of tax										319,000,000
Voluntary Retirement Program | Other Operations and Maintenance
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Voluntary retirement program related charges										251,000,000
Voluntary Retirement Program | Other Taxes
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Voluntary retirement program related charges										21,000,000
Voluntary Retirement Program | Other Income
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Voluntary retirement program related charges										111,000,000
Voluntary Retirement Program | Net Income Including Noncontrolling Interest From Discontinued Operations
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Voluntary retirement program related charges										44,000,000
Voluntary Retirement Program | Virginia Electric and Power Company
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Voluntary retirement program related charges										198,000,000
Voluntary retirement program related charges net of tax										146,000,000
Voluntary Retirement Program | Virginia Electric and Power Company | Other Operations and Maintenance
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Voluntary retirement program related charges										190,000,000
Voluntary Retirement Program | Virginia Electric and Power Company | Other Taxes
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Voluntary retirement program related charges										$ 8,000,000

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