Operating Segments (Schedule of Segment Information) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Segment Reporting Information [Line Items]
External revenue	$ 755	$ 795	$ 2,051	$ 1,158
Comprehensive income (loss) available (attributable) to common shareholder	101	143	258	(1,044)
Dominion Energy South Carolina | Operating Segment
Segment Reporting Information [Line Items]
External revenue	755	795	2,051	2,167
Comprehensive income (loss) available (attributable) to common shareholder	153	168	319	320
Corporate and Other | Operating Segment
Segment Reporting Information [Line Items]
External revenue	0	0	0	(1,009)
Comprehensive income (loss) available (attributable) to common shareholder	$ (52)	$ (25)	$ (61)	$ (1,364)