Operating Segments (Narrative) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Segment Reporting Information [Line Items]
Charge for refund of amounts from customers	$ 73	$ 70
Operating Segment | Corporate and Other
Segment Reporting Information [Line Items]
After- tax net expenses	212	104	$ 1,600
Operating Segment | Dominion Energy South Carolina [Member]
Segment Reporting Information [Line Items]
After- tax net expenses	208
Litigation charges	70	99	590
Litigation charges, after tax	53	$ 74	444
Charge for refund of amounts from customers			1,000
Charge for refund of amounts from customers, after tax			756
Income tax related to regulatory assets acquired			194
Income tax related to regulatory assets acquired, after tax			258
Charge for utility plant but committed to forgo recovery			114
Charge for utility plant but committed to forgo recovery, after tax			86
Merger-related costs			100
Merger-related costs, after tax			76
Charge related to a voluntary retirement program			79
Charge related to a voluntary retirement program, after-tax			59
Changes in unrecognized tax benefits			$ 66
Operating Segment | South Carolina Electric Base Rate Case
Segment Reporting Information [Line Items]
Settlement charges	266
Settlement charges net of tax	$ 199