Regulatory Matters (Narrative) (Details) $ in Millions			1 Months Ended										6 Months Ended	12 Months Ended	15 Months Ended
		Mar. 31, 2017 USD ($)	Jul. 31, 2017 USD ($) Case	Jun. 30, 2017 USD ($) program	May 31, 2017 USD ($)	Apr. 30, 2017 kV mi	Jun. 30, 2016 USD ($)	Mar. 31, 2016 kV mi	Nov. 30, 2013 kV mi	Aug. 31, 2009 kV	Apr. 30, 2008	Apr. 30, 2007 kV	Jun. 30, 2017 USD ($) power_station	Mar. 31, 2018 USD ($)	Jun. 30, 2018 USD ($)	Sep. 30, 2017 USD ($)	Dec. 31, 2016 USD ($)
Public Utilities, General Disclosures [Line Items]
Regulatory assets-noncurrent				$ 2,487									$ 2,487				$ 2,473	[1]
Regulatory asset recovered through retail rates
Public Utilities, General Disclosures [Line Items]
Regulatory assets-noncurrent	[2]			207									207				192
Virginia Electric and Power Company
Public Utilities, General Disclosures [Line Items]
ROE (percentage)											11.40%
Regulatory assets-noncurrent				851									851				770	[3]
Proposed revenue requirement					$ 625
Virginia Electric and Power Company | Rider T1
Public Utilities, General Disclosures [Line Items]
Proposed revenue requirement					135
Virginia Electric and Power Company | Regulatory asset recovered through retail rates
Public Utilities, General Disclosures [Line Items]
Regulatory assets-noncurrent	[2]			207									207				$ 192
Virginia Electric and Power Company | Transmission Component of Base Rate
Public Utilities, General Disclosures [Line Items]
Proposed revenue requirement					490
Virginia Electric and Power Company | FERC Gas Regulation | Order Regarding Transmission Rate Design for Allocation of Costs among PJM Interconnect LLC Transmission Customers | Unfavorable Regulatory Action | Settled Litigation
Public Utilities, General Disclosures [Line Items]
Amount required to pay under settlement agreement (in excess of $200 million)							$ 200
Duration of payment under settlement agreement							10 years
Amount of contingent liability				215									215
Virginia Electric and Power Company | FERC Gas Regulation | Order Regarding Transmission Rate Design for Allocation of Costs among PJM Interconnect LLC Transmission Customers | Unfavorable Regulatory Action | Settled Litigation | Regulatory asset recovered through retail rates
Public Utilities, General Disclosures [Line Items]
Regulatory assets-noncurrent				207									$ 207
Virginia Electric and Power Company | Virginia Regulation | Scenario, Forecast
Public Utilities, General Disclosures [Line Items]
Obligated to make payments to fund improvements for historical and cultural resiurces																$ 90
Virginia Electric and Power Company | Virginia Regulation | Transmission Line between Cunningham switching station and Dooms substation
Public Utilities, General Disclosures [Line Items]
Length of kV line (miles) | mi								33
Capacity of transmission line (kV) | kV								500
Total estimated cost of project					60
Virginia Electric and Power Company | Virginia Regulation | Surry Switching Station Transmission Line
Public Utilities, General Disclosures [Line Items]
Length of kV line (miles) | mi									7
Capacity of transmission line (kV) | kV									500
Virginia Electric and Power Company | Virginia Regulation | Transmission Line from Skiffes Creek Switching Station to Wheaton Substation
Public Utilities, General Disclosures [Line Items]
Length of kV line (miles) | mi									20
Capacity of transmission line (kV) | kV									230
Virginia Electric and Power Company | Virginia Regulation | Transmission Line Near Gainesville Substation and Haymarket Substation
Public Utilities, General Disclosures [Line Items]
Length of kV line (miles) | mi						5
Capacity of transmission line (kV) | kV						230
Virginia Electric and Power Company | Virginia Regulation | Annual Fuel Factor Submitted to the Virginia Commission
Public Utilities, General Disclosures [Line Items]
Proposed revenue requirement					1,600
Increase (decrease) in revenue requirement					$ 279
Virginia Electric and Power Company | Virginia Regulation | Rider S
Public Utilities, General Disclosures [Line Items]
Proposed revenue requirement				245
Increase (decrease) in revenue requirement				2
Virginia Electric and Power Company | Virginia Regulation | Rider W
Public Utilities, General Disclosures [Line Items]
Proposed revenue requirement				126
Increase (decrease) in revenue requirement				5
Virginia Electric and Power Company | Virginia Regulation | Rider R
Public Utilities, General Disclosures [Line Items]
Proposed revenue requirement				74
Increase (decrease) in revenue requirement				2
Virginia Electric and Power Company | Virginia Regulation | Rider B
Public Utilities, General Disclosures [Line Items]
Proposed revenue requirement				42
Increase (decrease) in revenue requirement				15
Number of power stations | power_station													3
Virginia Electric and Power Company | Virginia Regulation | Rider GV
Public Utilities, General Disclosures [Line Items]
Proposed revenue requirement				104
Increase (decrease) in revenue requirement				$ 22
Virginia Electric and Power Company | Virginia Regulation | Riders C1A and C2A
Public Utilities, General Disclosures [Line Items]
ROE (percentage)				9.40%
Approved revenue required				$ 28
Number of new energy efficiency programs | program				1
Virginia Electric and Power Company | Virginia Regulation | Rider BW
Public Utilities, General Disclosures [Line Items]
Approved revenue required				$ 127
Virginia Electric and Power Company | Virginia Regulation | Rider US-2
Public Utilities, General Disclosures [Line Items]
Approved revenue required				10
Virginia Electric and Power Company | Virginia Regulation | Rider T1
Public Utilities, General Disclosures [Line Items]
Increase (decrease) in revenue requirement			$ (55)
Virginia Electric and Power Company | Virginia Regulation | Subsequent Event | Transmission Line Near Gainesville Substation and Haymarket Substation
Public Utilities, General Disclosures [Line Items]
Number of requests to evaluate and reconsider its decision over the case | Case			2
Virginia Electric and Power Company | Minimum
Public Utilities, General Disclosures [Line Items]
Facility operating capacity (kV) | kV										500		500
Virginia Electric and Power Company | Maximum | Virginia Regulation | Riders C1A and C2A | Peak Shaving Program
Public Utilities, General Disclosures [Line Items]
Amount of cost recovery				$ 5
DETI | FERC Gas Regulation | Subsequent Event | Other Operations And Maintenance Expense | Preliminary recommendation one
Public Utilities, General Disclosures [Line Items]
Audit compliance charge recognized in connection with preliminary recommendation			$ 15
Audit compliance after-tax charge recognized in connection with preliminary recommendation			9
DETI | FERC Gas Regulation | Subsequent Event | Other Operations And Maintenance Expense | Other preliminary recommendation
Public Utilities, General Disclosures [Line Items]
Audit compliance charge recognized in connection with preliminary recommendation			0
Audit compliance after-tax charge recognized in connection with preliminary recommendation			$ 0
East Ohio | Ohio Regulation | PIPP Plus Program
Public Utilities, General Disclosures [Line Items]
Refund of overrecovery of accumulated arrearages		$ 20
East Ohio | Ohio Regulation | UEX Rider
Public Utilities, General Disclosures [Line Items]
Elimination of over-recovered balance of accumulated bad debt expense		$ 12
East Ohio | Ohio Regulation | Scenario, Forecast | PIPP Plus Program
Public Utilities, General Disclosures [Line Items]
Recovery of projected deferred program costs															$ 19
East Ohio | Ohio Regulation | Scenario, Forecast | UEX Rider
Public Utilities, General Disclosures [Line Items]
Prospective bad debt expense recovered														$ 22
East Ohio | Ohio Regulation | Subsequent Event | PIPP Plus Program
Public Utilities, General Disclosures [Line Items]
Approval waiting period from date of filing			45 days

[1] Dominion Energy’s Consolidated Balance Sheet at December 31, 2016 has been derived from the audited Consolidated Balance Sheet at that date.

[2] Reflects amounts related to the PJM transmission cost allocation matter. See Note 12 for more information.

[3] Virginia Power’s Consolidated Balance Sheet at December 31, 2016 has been derived from the audited Consolidated Balance Sheet at that date.