Operating Revenue (Schedule of Operating Revenue) (Detail) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Public Utilities General Disclosures [Line Items]
Operating revenue from contracts with customers		$ 3,536	$ 3,623	$ 10,350	$ 9,993
Other revenues	[1],[2]	71	159	301	513
Total operating revenue		3,607	3,782	10,651	10,506
Regulated Electric Sales | Residential
Public Utilities General Disclosures [Line Items]
Operating revenue from contracts with customers		1,497	1,440	3,746	3,180
Regulated Electric Sales | Commercial
Public Utilities General Disclosures [Line Items]
Operating revenue from contracts with customers		865	962	2,391	2,347
Regulated Electric Sales | Industrial
Public Utilities General Disclosures [Line Items]
Operating revenue from contracts with customers		190	227	548	474
Regulated Electric Sales | Government and Other Retail
Public Utilities General Disclosures [Line Items]
Operating revenue from contracts with customers		239	244	651	658
Regulated Electric Sales | Wholesale
Public Utilities General Disclosures [Line Items]
Operating revenue from contracts with customers		37	45	99	134
Nonregulated Electric Sales
Public Utilities General Disclosures [Line Items]
Operating revenue from contracts with customers		218	197	627	688
Regulated Gas Sales | Residential
Public Utilities General Disclosures [Line Items]
Operating revenue from contracts with customers		123	121	853	905
Regulated Gas Sales | Commercial
Public Utilities General Disclosures [Line Items]
Operating revenue from contracts with customers		50	52	304	311
Regulated Gas Sales | Other
Public Utilities General Disclosures [Line Items]
Operating revenue from contracts with customers		18	23	61	84
Nonregulated Gas Sales
Public Utilities General Disclosures [Line Items]
Operating revenue from contracts with customers		12	51	124	369
Regulated Gas Transportation and Storage - State
Public Utilities General Disclosures [Line Items]
Operating revenue from contracts with customers		165	168	578	547
Other Regulated Revenues
Public Utilities General Disclosures [Line Items]
Operating revenue from contracts with customers	[3]	61	54	236	184
Other Nonregulated Revenues
Public Utilities General Disclosures [Line Items]
Operating revenue from contracts with customers	[3],[4]	61	39	132	112
Virginia Electric and Power Company
Public Utilities General Disclosures [Line Items]
Operating revenue from contracts with customers		2,231	2,250	5,905	6,116
Other revenues	[2],[4]	17	14	78	51
Total operating revenue		2,248	2,264	5,983	6,167
Virginia Electric and Power Company | Regulated Electric Sales | Residential
Public Utilities General Disclosures [Line Items]
Operating revenue from contracts with customers		1,146	1,085	2,860	2,816
Virginia Electric and Power Company | Regulated Electric Sales | Commercial
Public Utilities General Disclosures [Line Items]
Operating revenue from contracts with customers		645	732	1,805	2,049
Virginia Electric and Power Company | Regulated Electric Sales | Industrial
Public Utilities General Disclosures [Line Items]
Operating revenue from contracts with customers		98	121	284	351
Virginia Electric and Power Company | Regulated Electric Sales | Government and Other Retail
Public Utilities General Disclosures [Line Items]
Operating revenue from contracts with customers		223	224	603	625
Virginia Electric and Power Company | Regulated Electric Sales | Wholesale
Public Utilities General Disclosures [Line Items]
Operating revenue from contracts with customers		25	31	70	97
Virginia Electric and Power Company | Other Regulated Revenues
Public Utilities General Disclosures [Line Items]
Operating revenue from contracts with customers		61	36	217	124
Virginia Electric and Power Company | Other Nonregulated Revenues
Public Utilities General Disclosures [Line Items]
Operating revenue from contracts with customers	[3],[4]	$ 33	$ 21	$ 66	$ 54

[1] Amounts above include revenue associated with services provided to discontinued operations of $1 million and $4 million for both the three and nine months ended September 30, 2020 and 2019, respectively.

[2] Amounts above include alternative revenue of $51 million and $9 million at Dominion Energy and $12 million and $9 million at Virginia Power for the three months ended September 30, 2020 and 2019, respectively, and $90 million and $44million at Dominion Energy and $63 million and $35 million at Virginia Power for the nine months ended September 30, 2020 and 2019, respectively.

[3] Amounts above include sales which are considered to be goods transferred at a point in time. Such amounts included $5 million for the three months ended September 30, 2020, $12 million for the three months ended September 30, 2019, $16 million for the nine months ended September 30, 2020 and $29 million for the nine months ended September 30, 2019, primarily consisting of sales of commodities related to nonregulated extraction activities and other miscellaneous products. Additionally, amounts above include sales of renewable energy credits. Such amounts included $21 million and $16 million for the three months ended September 30, 2020, $12 million and $11 million for the three months ended September 30, 2019, $32 million and $24 million for the nine months ended September 30, 2020 and $19 million and $14 million for the nine months ended September 30, 2019, at Dominion Energy and Virginia Power, respectively.

[4] See Notes 10 and 19 for amounts attributable to related parties and affiliates.