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Fair Value Measurements Fair Value, Option, Quantitative Disclosures (Details) (USD $)
In Millions, unless otherwise specified
 3 Months Ended
Mar. 31, 2015
Dec. 31, 2014
Fair Value, Option, Quantitative Disclosures [Line Items]    
Fair Value of Derivative Assets $ 679us-gaap_DerivativeAssets $ 719us-gaap_DerivativeAssets
Fair Value of Derivative Liabilities 765us-gaap_DerivativeLiabilities 794us-gaap_DerivativeLiabilities
Level 3    
Fair Value, Option, Quantitative Disclosures [Line Items]    
Fair Value of Derivative Assets 94us-gaap_DerivativeAssets
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Fair Value of Derivative Liabilities 18us-gaap_DerivativeLiabilities
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Level 3 | Natural Gas | Physical and Financial Forwards and Futures:    
Fair Value, Option, Quantitative Disclosures [Line Items]    
Fair Value of Derivative Assets 85us-gaap_DerivativeAssets
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Fair Value of Derivative Liabilities 12us-gaap_DerivativeLiabilities
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Fair Value, Option, Quantitative Disclosures [Line Items]    
Fair Value of Derivative Assets 5us-gaap_DerivativeAssets
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Level 3 | FTRs | Physical and Financial Forwards and Futures:    
Fair Value, Option, Quantitative Disclosures [Line Items]    
Fair Value of Derivative Assets 4us-gaap_DerivativeAssets
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Level 3 | Fair Value, Option, Quantitative Disclosures, Assets | Natural Gas | Physical and Financial Forwards and Futures: | Minimum    
Fair Value, Option, Quantitative Disclosures [Line Items]    
Market Price (per unit) (2)d_FairValueAssumptionsMarketPrice
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Credit spread (percentage) 1.00%us-gaap_FairValueInputsEntityCreditRisk
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Level 3 | Fair Value, Option, Quantitative Disclosures, Assets | Natural Gas | Physical and Financial Forwards and Futures: | Maximum    
Fair Value, Option, Quantitative Disclosures [Line Items]    
Market Price (per unit) 6d_FairValueAssumptionsMarketPrice
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Credit spread (percentage) 5.00%us-gaap_FairValueInputsEntityCreditRisk
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Level 3 | Fair Value, Option, Quantitative Disclosures, Assets | Natural Gas | Physical and Financial Forwards and Futures: | Wieghted Average    
Fair Value, Option, Quantitative Disclosures [Line Items]    
Market Price (per unit) (1)d_FairValueAssumptionsMarketPrice
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Credit spread (percentage) 2.00%us-gaap_FairValueInputsEntityCreditRisk
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Level 3 | Fair Value, Option, Quantitative Disclosures, Assets | Natural Gas | Physical and Financial Options: | Minimum    
Fair Value, Option, Quantitative Disclosures [Line Items]    
Market Price (per unit) 2d_FairValueAssumptionsMarketPrice
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Price Volatility (percentage) 21.00%d_PriceVolatility
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Level 3 | Fair Value, Option, Quantitative Disclosures, Assets | Natural Gas | Physical and Financial Options: | Maximum    
Fair Value, Option, Quantitative Disclosures [Line Items]    
Market Price (per unit) 4d_FairValueAssumptionsMarketPrice
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Price Volatility (percentage) 76.00%d_PriceVolatility
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Level 3 | Fair Value, Option, Quantitative Disclosures, Assets | Natural Gas | Physical and Financial Options: | Wieghted Average    
Fair Value, Option, Quantitative Disclosures [Line Items]    
Market Price (per unit) 3d_FairValueAssumptionsMarketPrice
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Price Volatility (percentage) 32.00%d_PriceVolatility
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Level 3 | Fair Value, Option, Quantitative Disclosures, Assets | FTRs | Physical and Financial Forwards and Futures: | Minimum    
Fair Value, Option, Quantitative Disclosures [Line Items]    
Market Price (per unit) (5)d_FairValueAssumptionsMarketPrice
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Level 3 | Fair Value, Option, Quantitative Disclosures, Assets | FTRs | Physical and Financial Forwards and Futures: | Maximum    
Fair Value, Option, Quantitative Disclosures [Line Items]    
Market Price (per unit) 7d_FairValueAssumptionsMarketPrice
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Level 3 | Fair Value, Option, Quantitative Disclosures, Assets | FTRs | Physical and Financial Forwards and Futures: | Wieghted Average    
Fair Value, Option, Quantitative Disclosures [Line Items]    
Market Price (per unit) 1d_FairValueAssumptionsMarketPrice
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Level 3 | Fair Value, Option, Quantitative Disclosures, Liabilities | Natural Gas | Physical and Financial Forwards and Futures: | Minimum    
Fair Value, Option, Quantitative Disclosures [Line Items]    
Market Price (per unit) (2)d_FairValueAssumptionsMarketPrice
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Level 3 | Fair Value, Option, Quantitative Disclosures, Liabilities | Natural Gas | Physical and Financial Forwards and Futures: | Maximum    
Fair Value, Option, Quantitative Disclosures [Line Items]    
Market Price (per unit) 4d_FairValueAssumptionsMarketPrice
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Level 3 | Fair Value, Option, Quantitative Disclosures, Liabilities | Natural Gas | Physical and Financial Forwards and Futures: | Wieghted Average    
Fair Value, Option, Quantitative Disclosures [Line Items]    
Market Price (per unit) 2d_FairValueAssumptionsMarketPrice
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Level 3 | Fair Value, Option, Quantitative Disclosures, Liabilities | Natural Gas | Physical and Financial Options: | Minimum    
Fair Value, Option, Quantitative Disclosures [Line Items]    
Market Price (per unit) 2d_FairValueAssumptionsMarketPrice
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Price Volatility (percentage) 21.00%d_PriceVolatility
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Level 3 | Fair Value, Option, Quantitative Disclosures, Liabilities | Natural Gas | Physical and Financial Options: | Maximum    
Fair Value, Option, Quantitative Disclosures [Line Items]    
Market Price (per unit) 4d_FairValueAssumptionsMarketPrice
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Price Volatility (percentage) 76.00%d_PriceVolatility
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Level 3 | Fair Value, Option, Quantitative Disclosures, Liabilities | Natural Gas | Physical and Financial Options: | Wieghted Average    
Fair Value, Option, Quantitative Disclosures [Line Items]    
Market Price (per unit) 3d_FairValueAssumptionsMarketPrice
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Price Volatility (percentage) 32.00%d_PriceVolatility
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Level 3 | Fair Value, Option, Quantitative Disclosures, Liabilities | FTRs | Physical and Financial Forwards and Futures: | Minimum    
Fair Value, Option, Quantitative Disclosures [Line Items]    
Market Price (per unit) (2)d_FairValueAssumptionsMarketPrice
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Level 3 | Fair Value, Option, Quantitative Disclosures, Liabilities | FTRs | Physical and Financial Forwards and Futures: | Maximum    
Fair Value, Option, Quantitative Disclosures [Line Items]    
Market Price (per unit) 5d_FairValueAssumptionsMarketPrice
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Level 3 | Fair Value, Option, Quantitative Disclosures, Liabilities | FTRs | Physical and Financial Forwards and Futures: | Wieghted Average    
Fair Value, Option, Quantitative Disclosures [Line Items]    
Market Price (per unit) 1d_FairValueAssumptionsMarketPrice
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Virginia Electric and Power Company    
Fair Value, Option, Quantitative Disclosures [Line Items]    
Fair Value of Derivative Assets 106us-gaap_DerivativeAssets
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Virginia Electric and Power Company | Level 3    
Fair Value, Option, Quantitative Disclosures [Line Items]    
Fair Value of Derivative Assets 82us-gaap_DerivativeAssets
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Virginia Electric and Power Company | Level 3 | Natural Gas | Physical and Financial Forwards and Futures:    
Fair Value, Option, Quantitative Disclosures [Line Items]    
Fair Value of Derivative Assets 78us-gaap_DerivativeAssets
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Virginia Electric and Power Company | Level 3 | FTRs | Physical and Financial Forwards and Futures:    
Fair Value, Option, Quantitative Disclosures [Line Items]    
Fair Value of Derivative Assets 4us-gaap_DerivativeAssets
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Fair Value of Derivative Liabilities $ 4us-gaap_DerivativeLiabilities
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Virginia Electric and Power Company | Level 3 | Fair Value, Option, Quantitative Disclosures, Assets | Natural Gas | Physical and Financial Forwards and Futures: | Minimum    
Fair Value, Option, Quantitative Disclosures [Line Items]    
Market Price (per unit) (2)d_FairValueAssumptionsMarketPrice
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Virginia Electric and Power Company | Level 3 | Fair Value, Option, Quantitative Disclosures, Assets | Natural Gas | Physical and Financial Forwards and Futures: | Maximum    
Fair Value, Option, Quantitative Disclosures [Line Items]    
Market Price (per unit) 3d_FairValueAssumptionsMarketPrice
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Virginia Electric and Power Company | Level 3 | Fair Value, Option, Quantitative Disclosures, Assets | Natural Gas | Physical and Financial Forwards and Futures: | Wieghted Average    
Fair Value, Option, Quantitative Disclosures [Line Items]    
Market Price (per unit) (1)d_FairValueAssumptionsMarketPrice
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/ d_FairValueOptionQuantativeDisclosuresAssetsLiabilitiesAxis
= d_FairValueOptionQuantitativeDisclosuresAssetsMember
/ dei_LegalEntityAxis
= d_VirginiaElectricAndPowerCompanyMember
/ us-gaap_RangeAxis
= us-gaap_WeightedAverageMember		 [2],[4]  
Credit spread (percentage) 2.00%us-gaap_FairValueInputsEntityCreditRisk
/ d_CommodityTypeAxis
= d_GasEnergyContractMember
/ us-gaap_EligibleItemOrGroupForFairValueOptionAxis
= d_PhysicalFinancialFowardsFuturesMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ d_FairValueOptionQuantativeDisclosuresAssetsLiabilitiesAxis
= d_FairValueOptionQuantitativeDisclosuresAssetsMember
/ dei_LegalEntityAxis
= d_VirginiaElectricAndPowerCompanyMember
/ us-gaap_RangeAxis
= us-gaap_WeightedAverageMember		 [3],[4]  
Virginia Electric and Power Company | Level 3 | Fair Value, Option, Quantitative Disclosures, Assets | FTRs | Physical and Financial Forwards and Futures: | Minimum    
Fair Value, Option, Quantitative Disclosures [Line Items]    
Market Price (per unit) (5)d_FairValueAssumptionsMarketPrice
/ d_CommodityTypeAxis
= d_FtrEnergyContractMember
/ us-gaap_EligibleItemOrGroupForFairValueOptionAxis
= d_PhysicalFinancialFowardsFuturesMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ d_FairValueOptionQuantativeDisclosuresAssetsLiabilitiesAxis
= d_FairValueOptionQuantitativeDisclosuresAssetsMember
/ dei_LegalEntityAxis
= d_VirginiaElectricAndPowerCompanyMember
/ us-gaap_RangeAxis
= us-gaap_MinimumMember		 [2]  
Virginia Electric and Power Company | Level 3 | Fair Value, Option, Quantitative Disclosures, Assets | FTRs | Physical and Financial Forwards and Futures: | Maximum    
Fair Value, Option, Quantitative Disclosures [Line Items]    
Market Price (per unit) 7d_FairValueAssumptionsMarketPrice
/ d_CommodityTypeAxis
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/ us-gaap_EligibleItemOrGroupForFairValueOptionAxis
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/ us-gaap_FairValueByFairValueHierarchyLevelAxis
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= d_FairValueOptionQuantitativeDisclosuresAssetsMember
/ dei_LegalEntityAxis
= d_VirginiaElectricAndPowerCompanyMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember		 [2]  
Virginia Electric and Power Company | Level 3 | Fair Value, Option, Quantitative Disclosures, Assets | FTRs | Physical and Financial Forwards and Futures: | Wieghted Average    
Fair Value, Option, Quantitative Disclosures [Line Items]    
Market Price (per unit) 1d_FairValueAssumptionsMarketPrice
/ d_CommodityTypeAxis
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/ us-gaap_EligibleItemOrGroupForFairValueOptionAxis
= d_PhysicalFinancialFowardsFuturesMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
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/ d_FairValueOptionQuantativeDisclosuresAssetsLiabilitiesAxis
= d_FairValueOptionQuantitativeDisclosuresAssetsMember
/ dei_LegalEntityAxis
= d_VirginiaElectricAndPowerCompanyMember
/ us-gaap_RangeAxis
= us-gaap_WeightedAverageMember		 [2],[4]  
Virginia Electric and Power Company | Level 3 | Fair Value, Option, Quantitative Disclosures, Liabilities | Natural Gas | Physical and Financial Forwards and Futures: | Minimum    
Fair Value, Option, Quantitative Disclosures [Line Items]    
Market Price (per unit) (2)d_FairValueAssumptionsMarketPrice
/ d_CommodityTypeAxis
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/ us-gaap_EligibleItemOrGroupForFairValueOptionAxis
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= d_QuantitativeDisclosuresLiabilitiesMember
/ dei_LegalEntityAxis
= d_VirginiaElectricAndPowerCompanyMember
/ us-gaap_RangeAxis
= us-gaap_MinimumMember		 [2]  
Virginia Electric and Power Company | Level 3 | Fair Value, Option, Quantitative Disclosures, Liabilities | Natural Gas | Physical and Financial Forwards and Futures: | Maximum    
Fair Value, Option, Quantitative Disclosures [Line Items]    
Market Price (per unit) 5d_FairValueAssumptionsMarketPrice
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/ dei_LegalEntityAxis
= d_VirginiaElectricAndPowerCompanyMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember		 [2]  
Virginia Electric and Power Company | Level 3 | Fair Value, Option, Quantitative Disclosures, Liabilities | FTRs | Physical and Financial Forwards and Futures: | Wieghted Average    
Fair Value, Option, Quantitative Disclosures [Line Items]    
Market Price (per unit) 1d_FairValueAssumptionsMarketPrice
/ d_CommodityTypeAxis
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/ us-gaap_EligibleItemOrGroupForFairValueOptionAxis
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/ dei_LegalEntityAxis
= d_VirginiaElectricAndPowerCompanyMember
/ us-gaap_RangeAxis
= us-gaap_WeightedAverageMember		 [2],[4]  
[1] Includes basis.
[2] Represents market prices beyond defined terms for Levels 1 and 2.
[3] Represents credit spreads unrepresented in published markets.
[4] Averages weighted by volume.
[5] Represents volatilities unrepresented in published markets.