Regulatory Matters (Narrative) (Details) MMBTU in Thousands	1 Months Ended										9 Months Ended
	Oct. 31, 2015 USD ($)	Sep. 30, 2015 USD ($)	Aug. 31, 2015 USD ($) MMBTU Program	Jan. 31, 2015 MW	Apr. 30, 2014 USD ($)	May. 31, 2012 USD ($)	Mar. 31, 2010 USD ($)	Aug. 31, 2009 kV	Apr. 30, 2008	Apr. 30, 2007 kV	Sep. 30, 2015 USD ($)	Dec. 31, 2014 USD ($)
Regulatory Matters [Line Items]
Total credit to customers		$ 2,288,000,000									$ 2,288,000,000	$ 2,161,000,000
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
Total credit to customers		$ 1,866,000,000									$ 1,866,000,000	$ 1,773,000,000
Virginia Electric and Power Company | Virginia Regulation
Regulatory Matters [Line Items]
Earned ROE percentage if Virginia Commission accepted all proposed adjustments		11.34%
Earned return percentage		10.13%
Projected fuel expenses			$ 1,600,000,000
Fuel revenue decrease			512,000,000
Capacity of solar facility (mw) | MW				20
Virginia Electric and Power Company | Virginia Regulation | Riders C1A and C2A
Regulatory Matters [Line Items]
Projected revenue requirement			$ 50,000,000
New energy efficiency programs | Program			2
Duration of cost cap			5 years
Amount of cost cap			$ 51,000,000
Extension period of cost cap			5 years
Virginia Electric and Power Company | Virginia Regulation | Rider BW | Subsequent Event
Regulatory Matters [Line Items]
Projected revenue requirement	$ 156,000,000
Revenue requirement increase (decrease)	45,000,000
Virginia Electric and Power Company | Virginia Regulation | Minimum
Regulatory Matters [Line Items]
ROE (percentage)											9.30%
Virginia Electric and Power Company | Virginia Regulation | Maximum
Regulatory Matters [Line Items]
ROE (percentage)											10.70%
Virginia Electric and Power Company | Virginia Regulation | Total credit to customers
Regulatory Matters [Line Items]
Total credit to customers		$ 65,000,000									$ 65,000,000
Virginia Electric and Power Company | North Carolina Regulation
Regulatory Matters [Line Items]
Amount of cost cap			$ 17,000,000
Revenue requirement increase (decrease)			$ (11,000,000)
Percentage of deferred fuel balance deferred			50.00%
DTI | FERC Gas Regulation | Clarington Project
Regulatory Matters [Line Items]
Expected cost					$ 80,000,000
Expected capacity of firm transportation service | MMBTU			250
Cove Point | FERC Gas Regulation | Subsequent Event | St Charles Transportation Project
Regulatory Matters [Line Items]
Expected cost	30,000,000
Cove Point | FERC Gas Regulation | Subsequent Event | Keys Energy Project
Regulatory Matters [Line Items]
Expected cost	$ 40,000,000