Employee Benefit Plans and Equity Compensation Plan (Narrative) (Detail) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Voluntary retirement program related charges						$ 63
Voluntary retirement program related charges net of taxes						47
Increase in pension benefit obligation	$ 25	$ 16
Increase in accumulated postretirement benefit obligation		10
Increase in fair value of pension plan assets	$ 35	$ 27
Defined benefit plan, accumulated benefit obligation				$ 697	$ 732
Gain (loss) from change in discount rate				$ (8)	(19)
Defined benefit plan, annual rate of increase in the per capita cost of covered health care benefits				6.25%
Defined benefit plan, ultimate health care cost trend rate				5.00%
Defined benefit plan, assumptions used calculating net periodic benefit cost, expected long-term rate of return on plan assets				7.00%
Defined benefit plan, contributions by employer				$ 0	0	0
Pension and other postretirement benefits				164	172
Defined contribution plan, employer matching contributions				$ 11	14	$ 14
Global Equities
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage				45.00%
Fixed Income
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage				53.00%
Cash
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage				2.00%
U.S Fixed Income
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage				60.00%
Non-U.S Fixed Income
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage				40.00%
Summer
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, shared costs deferred with joint ownership				$ 14	$ 19
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Discount rate percentage	3.57%	4.07%		3.06%	2.73%
Recognized actuarial gain (loss)				$ (29)	$ (43)
Defined benefit plan, assumptions used calculating net periodic benefit cost, expected long-term rate of return on plan assets				7.00%	7.00%	7.00%
Defined benefit plan, net periodic benefit (credit) cost				$ (13)	$ 4	$ 36
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Discount rate percentage		4.08%		3.11%	2.80%
Recognized actuarial gain (loss)					$ (51)
Defined benefit plan, ultimate health care cost trend rate				5.00%	5.00%	5.00%
Defined benefit plan, net periodic benefit (credit) cost				$ 7	$ 11	$ 15
Other Postretirement Benefits | Summer
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, shared costs deferred with joint ownership				12	$ 12
Dominion Energy Defined Benefit Plans
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, contributions by employer				0
Defined benefit plan, net periodic benefit (credit) cost				3
Pension and other postretirement benefits				$ 3
Dominion Energy Defined Benefit Plans | Maximum [Member] | Forecast
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, contributions by employer			$ 1
Other Operations and Maintenance Expense
Defined Benefit Plan Disclosure [Line Items]
Voluntary retirement program related charges						51
Other Taxes
Defined Benefit Plan Disclosure [Line Items]
Voluntary retirement program related charges						3
Other Income (Expense), Net
Defined Benefit Plan Disclosure [Line Items]
Voluntary retirement program related charges						9
Settlement losses as a result of voluntary retirement program						$ 16