Operating Segments - Schedule of Segment Information (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Segment Reporting Information [Line Items]
External revenue	$ 849	$ 744
Comprehensive income (loss) available (attributable) to common shareholder	103	51
Dominion Energy South Carolina, Inc.
Segment Reporting Information [Line Items]
External revenue	849	744
Comprehensive income (loss) available (attributable) to common shareholder	104	97
Corporate and Other
Segment Reporting Information [Line Items]
External revenue	0	0
Comprehensive income (loss) available (attributable) to common shareholder	$ (1)	$ (46)