Operating Segments (Schedule of Segment Reporting Information, by Segment) (Detail) - USD ($) $ in Millions		3 Months Ended								12 Months Ended
		Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019		Dec. 31, 2018		Dec. 31, 2017
Segment Reporting Information [Line Items]
Operating revenue		$ 4,475	$ 4,269	$ 3,970	$ 3,858	$ 3,361	$ 3,451	$ 3,088	$ 3,466	$ 16,572	[1]	$ 13,366	[1]	$ 12,586	[1]
Depreciation, depletion and amortization										2,655		2,000		1,905
Equity in earnings of equity method investees										168		197		(18)
Interest income										101		84		82
Interest and related charges										1,773		1,493		1,205
Income tax expense (benefit)										351		580		(30)
Net income (loss)		1,009	975	54	(680)	641	854	449	503	1,358		2,447		2,999
Investment in equity method investees		1,646				1,278				1,646		1,278
Capital expenditures										5,321
Total assets		103,823				77,914				103,823		77,914
Dominion Energy Gas Holdings, LLC
Segment Reporting Information [Line Items]
Operating revenue		571	502	530	566	566	533	508	389	2,169	[2]	1,996	[2]	1,523	[2]
Depreciation, depletion and amortization										367		333		242
Equity in earnings of equity method investees										43		54		47
Interest income										105		26		4
Interest and related charges	[2]									311		174		60
Income tax expense (benefit)										101		124		(65)
Net Income (loss) from discontinued operations	[3]									141		24		163
Net income (loss)		261	151	119	190	27	191	83	180	721		481		703
Investment in equity method investees		312				339				312		339
Capital expenditures										704		1,109		1,815
Total assets		18,784				26,751				18,784		26,751
Virginia Electric and Power Company
Segment Reporting Information [Line Items]
Operating revenue		1,941	2,264	1,938	1,965	1,810	2,232	1,829	1,748	8,108	[4]	7,619	[4]	7,556	[4]
Depreciation, depletion and amortization										1,223		1,132		1,141
Interest income										11		10		19
Interest and related charges	[4]									524		511		494
Income tax expense (benefit)										264		300		774
Net income (loss)		427	$ 602	$ 100	$ 20	239	$ 520	$ 339	$ 184	1,149		1,282		1,540
Capital expenditures										2,981		2,542		2,729
Total assets		41,428				36,880				41,428		36,880
Dominion Energy South Carolina
Segment Reporting Information [Line Items]
Operating revenue										2,948
Dominion Energy Virginia
Segment Reporting Information [Line Items]
Operating revenue										8,170		8,401		8,254
Dominion Energy Virginia | Virginia Electric and Power Company
Segment Reporting Information [Line Items]
Operating revenue										8,137		7,835		7,556
Depreciation, depletion and amortization										1,215		1,157		1,141
Interest income										11		10		19
Interest and related charges										529		516		497
Income tax expense (benefit)										481		378		868
Net income (loss)										1,783		1,594		1,466
Capital expenditures										2,981		2,542		2,729
Total assets		41,400				37,000				41,400		37,000
Gas, Transmission & Storage
Segment Reporting Information [Line Items]
Operating revenue										3,074		1,867		1,054
Gas, Transmission & Storage | Dominion Energy Gas Holdings, LLC
Segment Reporting Information [Line Items]
Operating revenue										2,186		1,996		1,523
Depreciation, depletion and amortization										367		333		242
Equity in earnings of equity method investees										43		54		47
Interest income										105		26		4
Interest and related charges										309		173		60
Income tax expense (benefit)										170		226		189
Net income (loss)										594		571		314
Investment in equity method investees		312				339				312		339
Capital expenditures										391		749		1,459
Total assets		18,800				19,900				18,800		19,900
Gas Distribution
Segment Reporting Information [Line Items]
Operating revenue										2,367		1,769		1,778
Contracted Generation
Segment Reporting Information [Line Items]
Operating revenue										1,135		1,487		1,345
Corporate and Other
Segment Reporting Information [Line Items]
Operating revenue										(1,122)		(249)		(27)
Corporate and Other | Dominion Energy Gas Holdings, LLC
Segment Reporting Information [Line Items]
Operating revenue										(17)
Interest income										0
Interest and related charges										2		1
Income tax expense (benefit)										(69)		(102)		(254)
Net Income (loss) from discontinued operations										141		24		163
Net income (loss)										127		(90)		389
Capital expenditures										313		360		356
Total assets		0				6,900				0		6,900
Corporate and Other | Virginia Electric and Power Company
Segment Reporting Information [Line Items]
Operating revenue										29		216
Depreciation, depletion and amortization										8		(25)
Interest and related charges										(5)		(5)		(3)
Income tax expense (benefit)										(217)		(78)		(94)
Net income (loss)										(634)		(312)		74
Total assets						(100)						(100)
Adjustments & Eliminations
Segment Reporting Information [Line Items]
Operating revenue												91		182
Interest income										(386)		(271)		(222)
Interest and related charges										(386)		(272)		(222)
Total assets		(9,700)				(12,900)				(9,700)		(12,900)
Intersegment revenue
Segment Reporting Information [Line Items]
Operating revenue										(1,470)		(918)		(1,008)
Intersegment revenue | Dominion Energy South Carolina
Segment Reporting Information [Line Items]
Operating revenue										4
Intersegment revenue | Dominion Energy Virginia
Segment Reporting Information [Line Items]
Operating revenue										(13)		(552)		(688)
Intersegment revenue | Gas, Transmission & Storage
Segment Reporting Information [Line Items]
Operating revenue										247		723		946
Intersegment revenue | Gas Distribution
Segment Reporting Information [Line Items]
Operating revenue										18		16		17
Intersegment revenue | Contracted Generation
Segment Reporting Information [Line Items]
Operating revenue										15		8		9
Intersegment revenue | Corporate and Other
Segment Reporting Information [Line Items]
Operating revenue										1,199		723		724
Eliminations
Segment Reporting Information [Line Items]
Operating revenue										(1,470)		(827)		(826)
Operating Segments
Segment Reporting Information [Line Items]
Capital expenditures												4,405		5,909
Operating Segments | Dominion Energy South Carolina
Segment Reporting Information [Line Items]
Operating revenue										2,952
Depreciation, depletion and amortization										452
Equity in earnings of equity method investees										(4)
Interest income										9
Interest and related charges										242
Income tax expense (benefit)										163
Net income (loss)										430
Capital expenditures										562
Total assets		15,800								15,800
Operating Segments | Dominion Energy Virginia
Segment Reporting Information [Line Items]
Operating revenue										8,157		7,849		7,566
Depreciation, depletion and amortization										1,216		1,158		1,141
Interest income										11		10		19
Interest and related charges										530		516		497
Income tax expense (benefit)										482		380		865
Net income (loss)										1,786		1,596		1,466
Capital expenditures										3,002		2,640		2,726
Total assets		43,700				39,100				43,700		39,100
Operating Segments | Gas, Transmission & Storage
Segment Reporting Information [Line Items]
Operating revenue										3,321		2,590		2,000
Depreciation, depletion and amortization										400		348		260
Equity in earnings of equity method investees										161		178		158
Interest income										211		143		114
Interest and related charges										405		262		100
Income tax expense (benefit)										262		236		291
Net income (loss)										934		844		552
Investment in equity method investees		1,517				1,159				1,517		1,159
Capital expenditures										431		765		1,489
Total assets		20,900				22,600				20,900		22,600
Operating Segments | Gas Distribution
Segment Reporting Information [Line Items]
Operating revenue										2,385		1,785		1,795
Depreciation, depletion and amortization										335		263		258
Equity in earnings of equity method investees										2
Interest income										4
Interest and related charges										116		79		72
Income tax expense (benefit)										114		95		195
Net income (loss)										488		373		351
Investment in equity method investees		32								32
Capital expenditures										848		647		452
Total assets		16,000				11,800				16,000		11,800
Operating Segments | Contracted Generation
Segment Reporting Information [Line Items]
Operating revenue										1,150		1,495		1,354
Depreciation, depletion and amortization										179		213		200
Equity in earnings of equity method investees										(1)		18		(171)
Interest income										92		80		77
Interest and related charges										98		124		110
Income tax expense (benefit)										20		75		(160)
Net income (loss)										276		245		253
Investment in equity method investees		74				82				74		82
Capital expenditures										367		247		979
Total assets		10,200				9,000				10,200		9,000
Operating Segments | Corporate and Other
Segment Reporting Information [Line Items]
Operating revenue										77		474		697
Depreciation, depletion and amortization										73		18		46
Equity in earnings of equity method investees										10		1		(5)
Interest income										160		122		94
Interest and related charges										768		784		648
Income tax expense (benefit)										(690)		(206)		(1,221)
Net income (loss)										(2,556)		(611)		377
Investment in equity method investees		23				37				23		37
Capital expenditures										111		106		$ 263
Total assets		$ 6,900				$ 8,300				$ 6,900		$ 8,300

[1] See Note 9 for amounts attributable to related parties.

[2] See Note 25 for amounts attributable to related parties.

[3] Includes income tax expense of $33 million, less than $1 million and $91 million in 2019, 2018 and 2017, respectively.

[4] See Note 25 for amounts attributable to affiliates.