Regulatory Matters (Narrative) (Details) customer in Millions, $ in Millions		1 Months Ended									3 Months Ended			12 Months Ended
		Apr. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Feb. 28, 2017 USD ($)	Oct. 31, 2016 USD ($) program	Aug. 31, 2016	Jun. 30, 2016 USD ($)	Aug. 31, 2009 kV	Apr. 30, 2008	Apr. 30, 2007 kV	Dec. 31, 2017 USD ($) MW	Mar. 31, 2017 USD ($) power_station kV mi	Mar. 31, 2016 USD ($)	Dec. 31, 2008	Dec. 31, 2007 customer	Dec. 31, 2016 USD ($)
Public Utilities, General Disclosures [Line Items]
Regulatory assets-noncurrent			$ 2,439									$ 2,439				$ 2,473	[1]
Acquisition of solar development projects												94	$ 0
Regulatory asset recovered through retail rates
Public Utilities, General Disclosures [Line Items]
Regulatory assets-noncurrent	[2]		200									200				192
Virginia Electric and Power Company
Public Utilities, General Disclosures [Line Items]
ROE (percentage)									11.40%
Regulatory assets-noncurrent			776									776				770	[3]
Virginia Electric and Power Company | Regulatory asset recovered through retail rates
Public Utilities, General Disclosures [Line Items]
Regulatory assets-noncurrent	[2]		200									200				192
Virginia Electric and Power Company | Minimum
Public Utilities, General Disclosures [Line Items]
Facility operating capacity (kV) | kV								500		500
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			208									208
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			200									$ 200
Virginia Electric and Power Company | Virginia Regulation | North Anna | Intent to Sue Notification Received from Sierra Club Alleging Endangered Species Act Violations
Public Utilities, General Disclosures [Line Items]
Period of notice of intent to sue						60 days
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
Total estimated cost of project			55									$ 55
Virginia Electric and Power Company | Virginia Regulation | Transmission Line between Carson Switching Station a Terminus Near Rogers Road Switching Station
Public Utilities, General Disclosures [Line Items]
Length of kV line (miles) | mi												28
Capacity of transmission line (kV) | kV												500
Total estimated cost of project			$ 55									$ 55
Virginia Electric and Power Company | Virginia Regulation | Virginia Commission 2015 Biennial Review
Public Utilities, General Disclosures [Line Items]
Proposed ROE percentage			10.50%
Virginia Electric and Power Company | Virginia Regulation | Application filed with Virginia Commission to Construct and Operate the Oceana Solar Facility [Member] | Solar Development Project | Scenario, Forecast
Public Utilities, General Disclosures [Line Items]
Acquisition of solar development projects											$ 40
MW facility | MW											18
Virginia Electric and Power Company | Virginia Regulation | Rider S
Public Utilities, General Disclosures [Line Items]
Approved revenue required				$ 243
Virginia Electric and Power Company | Virginia Regulation | Rider W
Public Utilities, General Disclosures [Line Items]
Approved revenue required				121
Virginia Electric and Power Company | Virginia Regulation | Rider R
Public Utilities, General Disclosures [Line Items]
Approved revenue required				72
Virginia Electric and Power Company | Virginia Regulation | Rider B
Public Utilities, General Disclosures [Line Items]
Approved revenue required				27
Number of power stations | power_station												3
Virginia Electric and Power Company | Virginia Regulation | Rider GV
Public Utilities, General Disclosures [Line Items]
Approved revenue required				$ 82
Virginia Electric and Power Company | Virginia Regulation | Riders C1A and C2A
Public Utilities, General Disclosures [Line Items]
Proposed revenue requirement					$ 45
Virginia Electric and Power Company | Virginia Regulation | Riders C1A and C2A | Energy Efficiency Program
Public Utilities, General Disclosures [Line Items]
Number of new energy efficiency programs | program					2
Period of cost cap					5 years
Duration of program					2 years
Virginia Electric and Power Company | Virginia Regulation | Riders C1A and C2A | Peak Shaving Program
Public Utilities, General Disclosures [Line Items]
Duration of program					5 years
Virginia Electric and Power Company | Virginia Regulation | Rider BW
Public Utilities, General Disclosures [Line Items]
Proposed revenue requirement					$ 134
Proposed revenue requirement increase (decrease)					15
Virginia Electric and Power Company | Virginia Regulation | Rider US-2
Public Utilities, General Disclosures [Line Items]
Proposed revenue requirement					10
Proposed revenue requirement increase (decrease)					6
Virginia Electric and Power Company | Virginia Regulation | Maximum | Riders C1A and C2A | Energy Efficiency Program
Public Utilities, General Disclosures [Line Items]
Amount of cost recovery					178
Virginia Electric and Power Company | Virginia Regulation | Maximum | Riders C1A and C2A | Peak Shaving Program
Public Utilities, General Disclosures [Line Items]
Amount of cost recovery					$ 5
Virginia Electric and Power Company | Virginia Regulation | Subsequent Event | Riders C1A and C2A
Public Utilities, General Disclosures [Line Items]
ROE (percentage)		9.40%
Virginia Electric and Power Company | Virginia Regulation | Subsequent Event | Rider BW
Public Utilities, General Disclosures [Line Items]
ROE (percentage)		10.40%
Virginia Electric and Power Company | Virginia Regulation | Subsequent Event | Rider US-2
Public Utilities, General Disclosures [Line Items]
ROE (percentage)		9.40%
East Ohio | Ohio Regulation
Public Utilities, General Disclosures [Line Items]
Amount of new cost recovery provision (up to $22 million)			$ 22									$ 22
East Ohio | Ohio Regulation | PIR
Public Utilities, General Disclosures [Line Items]
Percentage of pipeline system														25.00%
Gross plant investment																$ 188
East Ohio | Ohio Regulation | AMR Program
Public Utilities, General Disclosures [Line Items]
Number of customers | customer															1.2
East Ohio | Ohio Regulation | Subsequent Event | PIR
Public Utilities, General Disclosures [Line Items]
Proposed revenue requirement		$ 157
Gross plant investment		1,200
East Ohio | Ohio Regulation | Subsequent Event | AMR Program
Public Utilities, General Disclosures [Line Items]
Proposed revenue requirement		$ 6

[1] Dominion’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 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.