Commitments and Contingencies (Environmental Matters and Other Legal Matters) (Narrative) (Details)	1 Months Ended													3 Months Ended	12 Months Ended
	Apr. 30, 2017	Nov. 30, 2016 USD ($)	Jul. 31, 2016 party	Jun. 30, 2016 party	Apr. 30, 2016 USD ($)	Oct. 31, 2015	Jun. 30, 2015 party	Apr. 30, 2015 facility	Oct. 31, 2014 facility	Jun. 30, 2014 unit	Jul. 31, 2013 unit	Sep. 30, 2011 party	Jul. 31, 2011 state group MW	Mar. 31, 2016 party	Dec. 31, 2016 USD ($) facility party site		Dec. 31, 2015 USD ($)		Dec. 31, 2014 USD ($)
Loss Contingencies [Line Items]
Charges associated with future ash pond and landfill closure costs															$ 197,000,000		$ 99,000,000		$ 121,000,000
ARO recorded related to future ash pond and landfill closure costs															204,000,000	[1]	315,000,000	[2]
Legislation enacted | EPA | Maximum
Loss Contingencies [Line Items]
Period for consideration of CO2 emissions for biomass projects													3 years
Virginia Electric and Power Company
Loss Contingencies [Line Items]
Charges associated with future ash pond and landfill closure costs															197,000,000		99,000,000		121,000,000
ARO recorded related to future ash pond and landfill closure costs															9,000,000		289,000,000	[2]
Virginia Electric and Power Company | Legislation enacted | EPA
Loss Contingencies [Line Items]
Number of coal fired generating units | unit											3
DTI | Breach of Contract Lawsuit | Pending Litigation
Loss Contingencies [Line Items]
Amount of accrued liability															$ 6,000,000
Cove Point | Liquefaction Project | FERC | Pending Litigation
Loss Contingencies [Line Items]
Number of parties | party															2
Cove Point | Liquefaction Project | FERC | Judicial Ruling
Loss Contingencies [Line Items]
Number of parties | party			1				1
Dominion Gas Holdings, LLC
Loss Contingencies [Line Items]
ARO recorded related to future ash pond and landfill closure costs															$ 6,000,000		5,000,000
MATS | Legislation enacted | EPA
Loss Contingencies [Line Items]
Compliance extension period										1 year
Number of coal fired generating units | unit										2
Compliance extension period						1 year
MATS | Legislation enacted | EPA | Maximum
Loss Contingencies [Line Items]
Compliance extension period					1 year
MATS | Legislation enacted | EPA | Scenario, Forecast
Loss Contingencies [Line Items]
Period to be in service following receipt of all required permits	20 months
CSAPR | Legislation enacted | EPA
Loss Contingencies [Line Items]
Number of states under EPA Replacement Rule | state													28
Number of groups of affected states | group													2
CSAPR | Legislation enacted | EPA | Minimum
Loss Contingencies [Line Items]
Emissions of fossil fuel fired electric generating units | MW													25
Ozone Standards | Legislation enacted | EPA | Minimum
Loss Contingencies [Line Items]
Estimated compliance costs															25,000,000
Ozone Standards | Legislation enacted | EPA | Maximum
Loss Contingencies [Line Items]
Estimated compliance costs															$ 35,000,000
NOx and VOC Emissions | Dominion Gas Holdings, LLC | Legislation enacted | Pennsylvania Department of Environmental Protection
Loss Contingencies [Line Items]
Estimated compliance costs					$ 25,000,000
CERCLA | Legislation enacted | EPA
Loss Contingencies [Line Items]
Number of parties ordered specific remedial action | party												22
CERCLA | Virginia Electric and Power Company | Legislation enacted | EPA
Loss Contingencies [Line Items]
Cash settlement amount (less than $1 million)		$ 1,000,000
Coal Tar and Other Potentially Harmful Materials | Legislation enacted | EPA
Loss Contingencies [Line Items]
Number of former manufactured gas plant sites | site															19
Coal Tar and Other Potentially Harmful Materials | Legislation enacted | EPA | Former Gas Plant Site with Post Closure Groundwater Monitoring Program
Loss Contingencies [Line Items]
Number sites | site															1
Coal Tar and Other Potentially Harmful Materials | Virginia Electric and Power Company | Legislation enacted | EPA
Loss Contingencies [Line Items]
Number of former manufactured gas plant sites | site															3
Estimates for compliance, minimum															$ 1,000,000
Estimates for compliance, maximum															$ 22,000,000
Coal Tar and Other Potentially Harmful Materials | Dominion Gas Holdings, LLC | Legislation enacted | EPA
Loss Contingencies [Line Items]
Number of former manufactured gas plant sites | site															12
Clean Water Act | Legislation enacted
Loss Contingencies [Line Items]
Number of facilities | facility									14
Clean Water Act | Legislation enacted | EPA | Final Rule to Revise Effluent Limitations Guidelines for Steam Electric Power Generating Category
Loss Contingencies [Line Items]
Number of facilities subject to ruling | facility															8
Clean Water Act | Virginia Electric and Power Company | Possum Point Power Station | Other operations and maintenance expense
Loss Contingencies [Line Items]
Charges associated with future ash pond and landfill closure costs																			$ 121,000,000
Clean Water Act | Virginia Electric and Power Company | Legislation enacted
Loss Contingencies [Line Items]
Number of facilities | facility									11
CCR | Virginia Electric and Power Company | Legislation enacted | EPA | Environmental Protection Agency Final Rule Regulating Management of Coal Combustion Residual | Facilities Subject to Coal Combustion Residual Final Rule
Loss Contingencies [Line Items]
Number of facilities with CCR | facility								8
ARO recorded related to future ash pond and landfill closure costs															$ 238,000,000		386,000,000
CCR | Virginia Electric and Power Company | Legislation enacted | EPA | Environmental Protection Agency Final Rule Regulating Management of Coal Combustion Residual | Facilities Subject to Coal Combustion Residual Final Rule | Other operations and maintenance expense
Loss Contingencies [Line Items]
Incremental charge															197,000,000		99,000,000
CCR | Virginia Electric and Power Company | Legislation enacted | EPA | Environmental Protection Agency Final Rule Regulating Management of Coal Combustion Residual | Facilities Subject to Coal Combustion Residual Final Rule | Other Noncurrent Liabilities
Loss Contingencies [Line Items]
Reversal of contingent liability																	121,000,000
CCR | Virginia Electric and Power Company | Legislation enacted | EPA | Environmental Protection Agency Final Rule Regulating Management of Coal Combustion Residual | Facilities Subject to Coal Combustion Residual Final Rule | Remediation Property for Sale, Abandonment or Disposal
Loss Contingencies [Line Items]
Increase in property plant and equipment associated with asset retirement costs															17,000,000		$ 166,000,000
CCR | Virginia Electric and Power Company | Legislation enacted | EPA | Environmental Protection Agency Final Rule Regulating Management of Coal Combustion Residual | Facilities Subject to Coal Combustion Residual Final Rule | Remediation Property for Sale, Abandonment or Disposal | Asset Retirement Obligation Costs
Loss Contingencies [Line Items]
Increase in regulatory assets associated with asset retirement costs															$ 24,000,000
CCR | Virginia Electric and Power Company | Legislation enacted | EPA | Administrative Appeals in Circuit Court for City of Richmond | Environmental Protection Agency Final Rule Regulating Management of Coal Combustion Residual | Pending Litigation | Facilities Subject to Coal Combustion Residual Final Rule
Loss Contingencies [Line Items]
Number of parties | party														2
CCR | Virginia Electric and Power Company | Legislation enacted | EPA | Administrative Appeals in Circuit Court for City of Richmond | Environmental Protection Agency Final Rule Regulating Management of Coal Combustion Residual | Settled Litigation | Facilities Subject to Coal Combustion Residual Final Rule
Loss Contingencies [Line Items]
Number of parties | party				1

[1] Primarily reflects AROs assumed in the Dominion Questar Combination. See Note 3 for further information.

[2] Primarily reflects future ash pond and landfill closure costs at certain utility generation facilities. See Note 22 for further information.