Commitments and Contingencies (Narrative) (Details) (USD $)	1 Months Ended				3 Months Ended		12 Months Ended	1 Months Ended		56 Months Ended	1 Months Ended
	Jun. 30, 2014 Unit	Jul. 31, 2013 Unit	Sep. 30, 2011 Party	Jul. 31, 2011	Mar. 31, 2015 Site	Mar. 31, 2014	Dec. 31, 2014 Facility	Mar. 31, 2012 refueling_outage	Dec. 31, 2014	Mar. 31, 2015	Oct. 31, 2014 Facility
Investments in and Advances to Affiliates [Line Items]
Extension period for MATS compliance	1 year
Number of coal fired generating units	2	3
Requested compliance extension under EPA Administrative Order	1 year
Amount company has spent for emission standards compliance					$ 1,014,000,000	$ 1,120,000,000
Number of parties issued UAO			22
Daily civil penalties for non compliance					37,500
Number of former manufactured gas plant sites					17					17
Number of facilities with CCR							8
Maximum period for consideration of CO2 emissions from biomass projects				3 years
Purchased surety bonds					134,000,000					134,000,000
Authorized issuance of standby letters of credit					48,000,000					48,000,000
Third Party and Equity Method Investee
Investments in and Advances to Affiliates [Line Items]
Amount of civil penalty					74,000,000					74,000,000
NRC Safety Enhancements
Investments in and Advances to Affiliates [Line Items]
Number of refueling outages								2
Implementation period								4 years
Possum Point Power Station | Other Operations and Maintenance Expense
Investments in and Advances to Affiliates [Line Items]
Charge as a result of settlement offer									121,000,000
Virginia Electric and Power Company
Investments in and Advances to Affiliates [Line Items]
Amount company has spent for emission standards compliance					583,000,000	691,000,000
Number of former manufactured gas plant sites					3					3
Purchased surety bonds					65,000,000					65,000,000
Dominion Gas Holdings, LLC
Investments in and Advances to Affiliates [Line Items]
Amount company has spent for emission standards compliance					128,000,000	107,000,000
Number of former manufactured gas plant sites					12					12
Purchased surety bonds					30,000,000					30,000,000
CAA
Investments in and Advances to Affiliates [Line Items]
Number of states under EPA replacement rule				28
Emissions of fossil fuel fired electric generating units (MW)				25
Number of groups of affected states				2
Amount company has spent for emission standards compliance										2,000,000
CWA
Investments in and Advances to Affiliates [Line Items]
Number of facilities that may be subject to final regulations											14
CWA | Virginia Electric and Power Company
Investments in and Advances to Affiliates [Line Items]
Number of facilities that may be subject to final regulations											11
Remediation program
Investments in and Advances to Affiliates [Line Items]
Preliminary costs for options under evaluation for site, minimum					1,000,000					1,000,000
Preliminary costs for options under evaluation for site, maximum					22,000,000					22,000,000
Breach of Contract Lawsuit | Pending Litigation
Investments in and Advances to Affiliates [Line Items]
Accrued liability for legal matter					$ 6,000,000					$ 6,000,000