Acquisitions and Dispositions (Results of Operations and Pro Forma Information) (Narrative) (Detail) - SCANA - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Business Acquisition [Line Items]
Increase in operating revenue	$ 3,600	$ 3,300	$ 3,100
Increase (decrease) in net income	287	277	(1,100)
Merger and integration-related costs			427
Dominion Energy
Business Acquisition [Line Items]
Merger and integration-related costs	$ 31	$ 97	646
Voluntary Retirement Program | Dominion Energy
Business Acquisition [Line Items]
Merger and integration-related costs			427
Other Operations and Maintenance | Dominion Energy
Business Acquisition [Line Items]
Merger and integration-related costs			210
Interest and Related Charges | Dominion Energy
Business Acquisition [Line Items]
Merger and integration-related costs			$ 9