Employee Benefit Plans (Summary of Changes in Pension and Other Postretirement Benefit Plans) (Detail) - USD ($)		1 Months Ended	12 Months Ended
		Dec. 31, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Jun. 30, 2019
Changes in fair value of plan assets:
Employer contributions			$ 499,000,000
Amounts recognized in the Consolidated Balance Sheets at December 31:
Noncurrent pension and other postretirement benefit assets		$ 1,708,000,000	1,708,000,000	$ 1,279,000,000
Dominion Energy Gas Holdings, LLC
Changes in fair value of plan assets:
Employer contributions		0
Amounts recognized in the Consolidated Balance Sheets at December 31:
Noncurrent pension and other postretirement benefit assets	[1]	840,000,000	840,000,000	705,000,000
Noncurrent Assets of Discontinued Operations				5,849,000,000
Noncurrent liabilities of discontinued operations				(2,896,000,000)
Pension Benefits
Changes in benefit obligation:
Benefit obligation at beginning of year			8,500,000,000	9,052,000,000
Service cost			162,000,000	157,000,000	$ 138,000,000
Interest cost			394,000,000	337,000,000	345,000,000
Benefits paid			(470,000,000)	(358,000,000)
Actuarial (gains) losses during the year			1,054,000,000	(688,000,000)
Settlements and curtailments	[2]		(48,000,000)
Benefit obligation at end of year		10,446,000,000	10,446,000,000	8,500,000,000	9,052,000,000
Changes in fair value of plan assets:
Fair value of plan assets at beginning of year			7,197,000,000	8,062,000,000
Dominion Energy SCANA Combination			727,000,000
Actual return (loss) on plan assets			1,747,000,000	(513,000,000)
Employer contributions		520,000,000	557,000,000	6,000,000
Benefits paid			(470,000,000)	(358,000,000)
Settlements			(127,000,000)
Fair value of plan assets at end of year		9,631,000,000	9,631,000,000	7,197,000,000	8,062,000,000
Funded status at end of year		(815,000,000)	(815,000,000)	(1,303,000,000)
Amounts recognized in the Consolidated Balance Sheets at December 31:
Noncurrent pension and other postretirement benefit assets		1,266,000,000	1,266,000,000	1,003,000,000
Other current liabilities		(29,000,000)	(29,000,000)	(34,000,000)
Noncurrent pension and other postretirement benefit liabilities		(2,052,000,000)	(2,052,000,000)	(2,272,000,000)
Net amount recognized		$ (815,000,000)	$ (815,000,000)	$ (1,303,000,000)
Significant assumptions used to determine benefit obligations as of December 31:
Discount rate		3.63%	3.63%	4.42%
Weighted average rate of increase for compensation		4.23%	4.23%	4.32%
Pension Benefits | SCANA
Changes in benefit obligation:
Dominion Energy SCANA Combination			$ 854,000,000
Pension Benefits | Dominion Energy Gas Holdings, LLC
Changes in benefit obligation:
Benefit obligation at beginning of year			730,000,000	$ 773,000,000
Dominion Energy Gas Restructuring			(468,000,000)
Service cost			6,000,000	18,000,000	15,000,000
Interest cost			11,000,000	29,000,000	30,000,000
Benefits paid			(15,000,000)	(34,000,000)
Actuarial (gains) losses during the year			30,000,000	(56,000,000)
Settlements and curtailments	[2]		1,000,000
Benefit obligation at end of year		$ 295,000,000	295,000,000	730,000,000	773,000,000
Changes in fair value of plan assets:
Fair value of plan assets at beginning of year			1,656,000,000	1,803,000,000
Dominion Energy Gas Restructuring			(1,084,000,000)
Actual return (loss) on plan assets			129,000,000	(113,000,000)
Employer contributions			0
Benefits paid			(15,000,000)	(34,000,000)
Fair value of plan assets at end of year		686,000,000	686,000,000	1,656,000,000	1,803,000,000
Funded status at end of year		391,000,000	391,000,000	926,000,000
Amounts recognized in the Consolidated Balance Sheets at December 31:
Noncurrent pension and other postretirement benefit assets		391,000,000	391,000,000	310,000,000
Noncurrent Assets of Discontinued Operations				616,000,000
Net amount recognized		$ 391,000,000	$ 391,000,000	$ 926,000,000
Significant assumptions used to determine benefit obligations as of December 31:
Discount rate						4.10%
Weighted average rate of increase for compensation		4.64%	4.64%	4.55%
Pension Benefits | Minimum
Significant assumptions used to determine benefit obligations as of December 31:
Discount rate		3.47%	3.47%	4.42%		4.07%
Pension Benefits | Maximum
Significant assumptions used to determine benefit obligations as of December 31:
Discount rate		3.63%	3.63%	4.43%		4.10%
Other Postretirement Benefits
Changes in benefit obligation:
Benefit obligation at beginning of year			$ 1,363,000,000	$ 1,529,000,000
Service cost			26,000,000	27,000,000	26,000,000
Interest cost			68,000,000	56,000,000	60,000,000
Benefits paid			(96,000,000)	(87,000,000)
Actuarial (gains) losses during the year			111,000,000	(158,000,000)
Plan amendments				(4,000,000)
Settlements and curtailments	[2]		44,000,000
Benefit obligation at end of year		$ 1,769,000,000	1,769,000,000	1,363,000,000	1,529,000,000
Changes in fair value of plan assets:
Fair value of plan assets at beginning of year			1,581,000,000	1,729,000,000
Actual return (loss) on plan assets			349,000,000	(92,000,000)
Employer contributions			12,000,000	12,000,000
Benefits paid			(62,000,000)	(68,000,000)
Fair value of plan assets at end of year		1,880,000,000	1,880,000,000	1,581,000,000	1,729,000,000
Funded status at end of year		111,000,000	111,000,000	218,000,000
Amounts recognized in the Consolidated Balance Sheets at December 31:
Noncurrent pension and other postretirement benefit assets		442,000,000	442,000,000	276,000,000
Other current liabilities		(17,000,000)	(17,000,000)	(2,000,000)
Noncurrent pension and other postretirement benefit liabilities		(314,000,000)	(314,000,000)	(56,000,000)
Net amount recognized		$ 111,000,000	$ 111,000,000	$ 218,000,000
Significant assumptions used to determine benefit obligations as of December 31:
Discount rate		3.44%	3.44%	4.37%
Other Postretirement Benefits | SCANA
Changes in benefit obligation:
Dominion Energy SCANA Combination			$ 253,000,000
Other Postretirement Benefits | Dominion Energy Gas Holdings, LLC
Changes in benefit obligation:
Benefit obligation at beginning of year			256,000,000	$ 290,000,000
Dominion Energy Gas Restructuring			(135,000,000)
Service cost			1,000,000	4,000,000	4,000,000
Interest cost			5,000,000	11,000,000	12,000,000
Benefits paid			(8,000,000)	(18,000,000)
Actuarial (gains) losses during the year			1,000,000	(27,000,000)
Plan amendments				(4,000,000)
Settlements and curtailments	[2]		1,000,000
Benefit obligation at end of year		$ 121,000,000	121,000,000	256,000,000	290,000,000
Changes in fair value of plan assets:
Fair value of plan assets at beginning of year			311,000,000	333,000,000
Dominion Energy Gas Restructuring			(126,000,000)
Actual return (loss) on plan assets			38,000,000	(16,000,000)
Employer contributions			12,000,000	12,000,000
Benefits paid			(8,000,000)	(18,000,000)
Fair value of plan assets at end of year		227,000,000	227,000,000	311,000,000	$ 333,000,000
Funded status at end of year		106,000,000	106,000,000	55,000,000
Amounts recognized in the Consolidated Balance Sheets at December 31:
Noncurrent pension and other postretirement benefit assets		106,000,000	106,000,000	63,000,000
Noncurrent liabilities of discontinued operations				(8,000,000)
Net amount recognized		$ 106,000,000	$ 106,000,000	$ 55,000,000
Significant assumptions used to determine benefit obligations as of December 31:
Discount rate						4.05%
Other Postretirement Benefits | Minimum
Significant assumptions used to determine benefit obligations as of December 31:
Discount rate		3.44%	3.44%	4.37%		4.05%
Other Postretirement Benefits | Maximum
Significant assumptions used to determine benefit obligations as of December 31:
Discount rate		3.52%	3.52%	4.38%		4.08%

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

[2] 2019 amounts relate primarily to a settlement as a result of the voluntary retirement program.