Operating Segments - Schedule of Segment Information (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Segment Reporting Information [Line Items]
External revenue	$ 672	$ (335)
Comprehensive income (loss) available (attributable) to common shareholder	88	(1,109)
Dominion Energy South Carolina | Operating Segment
Segment Reporting Information [Line Items]
External revenue	672	674
Comprehensive income (loss) available (attributable) to common shareholder	89	64
Corporate and Other | Operating Segment
Segment Reporting Information [Line Items]
External revenue	0	(1,009)
Comprehensive income (loss) available (attributable) to common shareholder	$ (1)	$ (1,173)