Operating Segments (Schedule of Segment Reporting Information, by Segment) (Detail) - USD ($) $ in Millions		3 Months Ended									12 Months Ended
	Nov. 30, 2020	Dec. 31, 2020		Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020		Dec. 31, 2019		Dec. 31, 2018
Segment Reporting Information [Line Items]
Operating Revenue		$ 3,521		$ 3,607	$ 3,106	$ 3,938	$ 3,895	$ 3,782	$ 3,443	$ 3,281	$ 14,172		$ 14,401		$ 11,199
Depreciation, depletion and amortization											2,332		2,283		1,660
Equity in earnings(losses) on investments											40		8		76
Interest income											107		97		80
Interest and related charges											1,377		1,486		1,279
Income tax expense	$ 336										83		209		522
Net Income (Loss) From Discontinued Operations Including Noncontrolling Interest		(125)		19	(2,001)	229	190	38	257	231	(1,878)	[1],[2]	716	[1],[2]	452	[1],[2]
Net income (loss) attributable to Dominion Energy		682		$ 356	$ (1,169)	$ (270)	1,009	$ 975	$ 54	$ (680)	(401)		1,358		2,447
Investment in equity method affiliates		2,934	[3]				1,334				2,934	[3]	1,334
Capital expenditures											6,331		5,321		4,405
Total assets		95,905					103,823				95,905		103,823
Operating Segments
Segment Reporting Information [Line Items]
Operating Revenue											14,197		14,408		11,187
Adjustments & Eliminations
Segment Reporting Information [Line Items]
Operating Revenue											48		79		177
Depreciation, depletion and amortization											0		0		0
Equity in earnings(losses) on investments											0		0		0
Interest income											(88)		(136)		(108)
Interest and related charges											(88)		(136)		(108)
Income tax expense											0		0		0
Net Income (Loss) From Discontinued Operations Including Noncontrolling Interest											0		0		0
Net income (loss) attributable to Dominion Energy											0		0		0
Investment in equity method affiliates		0	[3]				0				0	[3]	0
Capital expenditures											0		0		0
Total assets		(4,900)					(5,900)				(4,900)		(5,900)
Intersegment revenue
Segment Reporting Information [Line Items]
Operating Revenue											(25)		(7)		12
Intersegment revenue
Segment Reporting Information [Line Items]
Operating Revenue											(1,039)		(1,160)		(675)
Eliminations
Segment Reporting Information [Line Items]
Operating Revenue											(991)		(1,081)		(498)
Dominion Energy Virginia
Segment Reporting Information [Line Items]
Operating Revenue											7,787		8,157		7,849
Dominion Energy Virginia | Operating Segments
Segment Reporting Information [Line Items]
Operating Revenue											7,802		8,170		8,401
Depreciation, depletion and amortization											1,247		1,216		1,158
Equity in earnings(losses) on investments											0		0		0
Interest income											13		11		10
Interest and related charges											527		530		516
Income tax expense											496		482		380
Net Income (Loss) From Discontinued Operations Including Noncontrolling Interest											0		0		0
Net income (loss) attributable to Dominion Energy											1,891		1,786		1,596
Investment in equity method affiliates		0	[3]				0				0	[3]	0
Capital expenditures											3,406		3,002		2,640
Total assets		46,000					43,700				46,000		43,700
Dominion Energy Virginia | Intersegment revenue
Segment Reporting Information [Line Items]
Operating Revenue											(15)		(13)		(552)
Gas Distribution
Segment Reporting Information [Line Items]
Operating Revenue											2,355		2,385		1,785
Gas Distribution | Operating Segments
Segment Reporting Information [Line Items]
Operating Revenue											2,345		2,367		1,769
Depreciation, depletion and amortization											344		335		263
Equity in earnings(losses) on investments											0		2		0
Interest income											6		4		0
Interest and related charges											76		116		79
Income tax expense											121		114		95
Net Income (Loss) From Discontinued Operations Including Noncontrolling Interest											0		0		0
Net income (loss) attributable to Dominion Energy											560		487		373
Investment in equity method affiliates		55	[3]				37				55	[3]	37
Capital expenditures											1,151		853		647
Total assets		17,100					16,000				17,100		16,000
Gas Distribution | Intersegment revenue
Segment Reporting Information [Line Items]
Operating Revenue											10		18		16
Dominion Energy South Carolina Inc | Operating Segments
Segment Reporting Information [Line Items]
Operating Revenue											2,782		2,948		0
Contracted Assets
Segment Reporting Information [Line Items]
Operating Revenue											1,071		1,156		1,434
Contracted Assets | Operating Segments
Segment Reporting Information [Line Items]
Operating Revenue											1,020		1,083		813
Depreciation, depletion and amortization											182		180		213
Equity in earnings(losses) on investments											35		(1)		18
Interest income											91		97		84
Interest and related charges											75		98		124
Income tax expense											(16)		20		75
Net Income (Loss) From Discontinued Operations Including Noncontrolling Interest											167		183		116
Net income (loss) attributable to Dominion Energy											402		460		361
Investment in equity method affiliates		2,784	[3]				74				2,784	[3]	74
Capital expenditures											649		367		247
Total assets		13,100					10,200				13,100		10,200
Contracted Assets | Intersegment revenue
Segment Reporting Information [Line Items]
Operating Revenue											51		73		621
Corporate and Other
Segment Reporting Information [Line Items]
Operating Revenue											1,163		832		629
Corporate and Other | Operating Segments
Segment Reporting Information [Line Items]
Operating Revenue											200		(239)		27
Depreciation, depletion and amortization											85		100		26
Equity in earnings(losses) on investments											6		11		58
Interest income											73		112		94
Interest and related charges											568		636		668
Income tax expense											(625)		(570)		(28)
Net Income (Loss) From Discontinued Operations Including Noncontrolling Interest											(2,045)		533		336
Net income (loss) attributable to Dominion Energy											(3,673)		(1,805)		117
Investment in equity method affiliates		95	[3]				1,223				95	[3]	1,223
Capital expenditures											425		537		871
Total assets		8,600					24,000				8,600		24,000
Corporate and Other | Intersegment revenue
Segment Reporting Information [Line Items]
Operating Revenue											963		1,071		602
Dominion Energy South Carolina
Segment Reporting Information [Line Items]
Operating Revenue											2,787		2,952		0
Dominion Energy South Carolina | Operating Segments
Segment Reporting Information [Line Items]
Depreciation, depletion and amortization											474		452		0
Equity in earnings(losses) on investments											(1)		(4)		0
Interest income											12		9		0
Interest and related charges											219		242		0
Income tax expense											107		163		0
Net Income (Loss) From Discontinued Operations Including Noncontrolling Interest											0		0		0
Net income (loss) attributable to Dominion Energy											419		430		0
Investment in equity method affiliates		0	[3]				0				0	[3]	0
Capital expenditures											700		562		0
Total assets		$ 16,000					$ 15,800				16,000		15,800
Dominion Energy South Carolina | Intersegment revenue
Segment Reporting Information [Line Items]
Operating Revenue											$ 5		$ 4		$ 0

[1] Includes income tax expense (benefit) of $(204) million, $142 million and $58 million for the years ended December 31, 2020, 2019 and 2018, respectively

[2] See Note 9 for amounts attributable to related parties

[3] Excludes liability to Atlantic Coast Pipeline.