Operating Revenue (Schedule of Operating Revenue Prior to Revised Guidance of Revenue Recognition From Contracts with Customers) (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
Public Utilities General Disclosures [Line Items]
Total 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]
Virginia Electric and Power Company
Public Utilities General Disclosures [Line Items]
Total operating revenue	1,941	2,264	1,938	1,965	1,810	2,232	1,829	1,748	8,108	[2]	7,619	[2]	7,556	[2]
Dominion Energy Gas Holdings, LLC
Public Utilities General Disclosures [Line Items]
Total operating revenue	$ 571	$ 502	$ 530	$ 566	$ 566	$ 533	$ 508	$ 389	$ 2,169	[3]	$ 1,996	[3]	1,523	[3]
Prior to adoption of revised guidance
Public Utilities General Disclosures [Line Items]
Nonregulated electric sales													1,429
Regulated gas sales													1,067
Nonregulated gas sales													457
Total operating revenue													12,586
Prior to adoption of revised guidance | Regulated Electric Sales
Public Utilities General Disclosures [Line Items]
Revenue													7,383
Prior to adoption of revised guidance | Gas Transportation and Storage
Public Utilities General Disclosures [Line Items]
Revenue													1,786
Prior to adoption of revised guidance | Other
Public Utilities General Disclosures [Line Items]
Revenue													464
Prior to adoption of revised guidance | Virginia Electric and Power Company
Public Utilities General Disclosures [Line Items]
Total operating revenue													7,556
Prior to adoption of revised guidance | Virginia Electric and Power Company | Regulated Electric Sales
Public Utilities General Disclosures [Line Items]
Revenue													7,383
Prior to adoption of revised guidance | Virginia Electric and Power Company | Other
Public Utilities General Disclosures [Line Items]
Revenue													173
Prior to adoption of revised guidance | Dominion Energy Gas Holdings, LLC
Public Utilities General Disclosures [Line Items]
Regulated gas sales													6
Nonregulated gas sales													6
Total operating revenue													1,523
Prior to adoption of revised guidance | Dominion Energy Gas Holdings, LLC | Gas Transportation and Storage
Public Utilities General Disclosures [Line Items]
Revenue													1,291
Prior to adoption of revised guidance | Dominion Energy Gas Holdings, LLC | Other
Public Utilities General Disclosures [Line Items]
Revenue													$ 220

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

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

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