Regulatory Matters (Narrative) (Details) MMBTU in Thousands, customer in Millions	1 Months Ended												3 Months Ended	12 Months Ended
	May. 31, 2016 USD ($)	Apr. 30, 2016 USD ($) Program	Mar. 31, 2016 USD ($)	Feb. 29, 2016 USD ($)	Dec. 31, 2015 USD ($)	Feb. 28, 2015 Test_Period	Jan. 31, 2015 USD ($) MW	May. 31, 2012 USD ($)	Mar. 31, 2010 USD ($)	Aug. 31, 2009 kV	Apr. 30, 2008	Apr. 30, 2007 kV	Mar. 31, 2016 USD ($) Power_Station	Dec. 31, 2014 USD ($) MMBTU Agreement	Dec. 31, 2013 USD ($) MMBTU	Dec. 31, 2008	Dec. 31, 2007 customer
Regulatory Matters [Line Items]
Regulatory asset			$ 2,328,000,000		$ 2,216,000,000								$ 2,328,000,000
Virginia Electric and Power Company
Regulatory Matters [Line Items]
ROE (percentage)											11.40%
Costs claimed to be unjust and excluded from transmission formula rate									$ 223,000,000
Potential settlement required annual payment for 10 Years								$ 250,000
Period for annual settlement payment								10 years
Facility operating capacity (kV) | kV										500		500
Regulatory asset			$ 1,118,000,000		993,000,000								$ 1,118,000,000
Virginia Electric and Power Company | Virginia Regulation
Regulatory Matters [Line Items]
Capacity of solar facility (mw) | MW							20
Virginia Electric and Power Company | Virginia Regulation | February 2015 Regulation Act Legislation
Regulatory Matters [Line Items]
ROE (percentage)				9.60%
Number of test periods | Test_Period						5
Virginia Electric and Power Company | Virginia Regulation | Rider S
Regulatory Matters [Line Items]
ROE (percentage)				10.60%
Approved revenue required				$ 251,000,000
Virginia Electric and Power Company | Virginia Regulation | Rider S | February 2015 Regulation Act Legislation
Regulatory Matters [Line Items]
ROE (percentage)				10.60%
Virginia Electric and Power Company | Virginia Regulation | Rider R
Regulatory Matters [Line Items]
ROE (percentage)				10.60%
Approved revenue required				$ 74,000,000
Virginia Electric and Power Company | Virginia Regulation | Rider R | February 2015 Regulation Act Legislation
Regulatory Matters [Line Items]
ROE (percentage)				10.60%
Virginia Electric and Power Company | Virginia Regulation | Rider W
Regulatory Matters [Line Items]
ROE (percentage)				10.60%
Approved revenue required				$ 118,000,000
Virginia Electric and Power Company | Virginia Regulation | Rider W | February 2015 Regulation Act Legislation
Regulatory Matters [Line Items]
ROE (percentage)				10.60%
Virginia Electric and Power Company | Virginia Regulation | Rider B
Regulatory Matters [Line Items]
ROE (percentage)				11.60%
Approved revenue required				$ 30,000,000
Number of power stations converted to biomass | Power_Station													3
Virginia Electric and Power Company | Virginia Regulation | Rider B | February 2015 Regulation Act Legislation
Regulatory Matters [Line Items]
ROE (percentage)				11.60%
Virginia Electric and Power Company | Virginia Regulation | Rider GV
Regulatory Matters [Line Items]
ROE (percentage)			9.60%
Approved revenue required			$ 40,000,000
Virginia Electric and Power Company | Virginia Regulation | Solar Development Project | Rider US-1
Regulatory Matters [Line Items]
Total estimated cost							$ 47,000,000
Virginia Electric and Power Company | Virginia Regulation | Subsequent Event | Riders C1A and C2A
Regulatory Matters [Line Items]
Approved revenue required		$ 46,000,000
Number of approved new energy efficiency programs | Program		1
Virginia Electric and Power Company | Virginia Regulation | Subsequent Event | Riders C1A and C2A | February 2015 Regulation Act Legislation
Regulatory Matters [Line Items]
ROE (percentage)		9.60%
Virginia Electric and Power Company | Virginia Regulation | Scenario, Forecast | Subsequent Event
Regulatory Matters [Line Items]
Amount of recovery of projected fuel expenses	$ 1,400,000,000
Amount of fuel revenue decrease	286,000,000
Virginia Electric and Power Company | Virginia Regulation | Scenario, Forecast | Subsequent Event | Rider T1
Regulatory Matters [Line Items]
Revenue requirement increase (decrease)	(29,000,000)
Projected revenue requirement	$ 639,000,000
Virginia Electric and Power Company | North Carolina Regulation
Regulatory Matters [Line Items]
ROE (percentage)			10.20%
Revenue requirement increase (decrease)			$ 51,000,000
Earned return percentage			5.06%
Earned ROE percentage if Virginia Commission accepted all proposed adjustments			10.50%
Virginia Electric and Power Company | North Carolina Regulation | Minimum
Regulatory Matters [Line Items]
Current cost of equity percentage			10.25%
Virginia Electric and Power Company | North Carolina Regulation | Maximum
Regulatory Matters [Line Items]
Current cost of equity percentage			10.75%
Virginia Electric and Power Company | North Carolina Regulation | Revenue Subject to Refund
Regulatory Matters [Line Items]
Period of implementation of new lower fuel rate			2 years
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 Matters [Line Items]
Amount required to pay under settlement agreement					$ 200,000,000
Duration of payment under settlement agreement					10 years
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 | Regulatory asset recovered through retail rates | Settled Litigation
Regulatory Matters [Line Items]
Regulatory asset					$ 192,000,000
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 | Other deferred credits and other liabilities | Settled Litigation
Regulatory Matters [Line Items]
Amount of contingent liability					200,000,000
East Ohio | Ohio Regulation | PIR Program
Regulatory Matters [Line Items]
Percentage of pipeline system																25.00%
Gross plant investment				$ 1,000,000,000	171,000,000
Projected revenue requirement				131,000,000
East Ohio | Ohio Regulation | AMR Program
Regulatory Matters [Line Items]
Projected revenue requirement				$ 7,000,000
Number of customers | customer																	1.2
DCG | FERC Gas Regulation | New Market Project
Regulatory Matters [Line Items]
Expected cost															$ 159,000,000
Amount of firm transportation service provided per day (in Dths) | MMBTU															112
DCG | FERC Gas Regulation | Transco to Charleston Project
Regulatory Matters [Line Items]
Number of binding precedent agreements | Agreement														3
Expected cost														$ 120,000,000
Amount of firm transportation service provided per day (in Dths) | MMBTU														80
Dominion Gas Holdings, LLC
Regulatory Matters [Line Items]
Regulatory asset			$ 465,000,000		$ 472,000,000								$ 465,000,000
Dominion Gas Holdings, LLC | FERC Gas Regulation | Subsequent Event | Authorization to Abandon by Sale Gathering and Processing Facilities | Gas Gathering and Processing Facilities
Regulatory Matters [Line Items]
Carrying value of gathering and processing facilities		$ 430,000,000