Employee Benefit Plans - EEGH - Defined Benefit Plans (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Distribution of net assets	$ 121,000,000	$ 22,000,000	$ 23,000,000
Eastern Energy Gas Holdings, LLC [Member]
Defined Benefit Plan Disclosure [Line Items]
Distribution of net assets	4,498,000,000	636,000,000	0
Eastern Energy Gas Holdings, LLC [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Contributions by Employer		0
Defined Benefit Plan, Plan Assets, Increase (Decrease) for Actual Return (Loss)		129,000,000
Eastern Energy Gas Holdings, LLC [Member] | MidAmerican Energy Pension Plan [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Contributions by Employer	3,000,000
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)	3,000,000
Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year	19,000,000
Eastern Energy Gas Holdings, LLC [Member] | MidAmerican Energy Pension Plan and Welfare Plan [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Contributions by Employer	2,000,000
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)	2,000,000
Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year	12,000,000
Eastern Energy Gas Holdings, LLC [Member] | Dominion Energy Pension Plan [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Contributions by Employer	0
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)	(14,000,000)	(8,000,000)	(35,000,000)
Eastern Energy Gas Holdings, LLC [Member] | Dominion Energy Retiree Health and Welfare Plan [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)	$ (5,000,000)	(4,000,000)	(8,000,000)
Eastern Energy Gas Holdings, LLC [Member] | Discontinued Operations, Disposed of by Means Other than Sale [Member] | Dominion Energy Pension Plan [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)		(14,000,000)	(21,000,000)
Eastern Energy Gas Holdings, LLC [Member] | Discontinued Operations, Disposed of by Means Other than Sale [Member] | Dominion Energy Retiree Health and Welfare Plan [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)		$ (1,000,000)	$ (2,000,000)