2.2.0.7 true Assets and Liabilities that are Measured at Fair Value on a Recurring Basis (Detail) (USD $) 153 - Disclosure - Assets and Liabilities that are Measured at Fair Value on a Recurring Basis (Detail) true false In Millions false false 1 USD false false iso4217_USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 shares Standard http://www.xbrl.org/2003/instance shares 0 $ false 2 USD false false iso4217_USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 shares Standard http://www.xbrl.org/2003/instance shares 0 $ 2 Assets 2 d_FairValueAssetsMeasuredOnRecurringBasisAbstract d false na duration Fair Value, Assets Measured on Recurring Basis [Abstract] false false false false false true false false false false false verboselabel false 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false xbrli:stringItemType string Fair Value, Assets Measured on Recurring Basis [Abstract] false 5 Total assets 2 d_FairValueAssetsMeasuredOnRecurringBasis d false debit instant This item reflects the aggregate amount of assets measured at fair value on a recurring basis. false false false false false false false false false false false totallabel false 1 true true false false 4074000000 4074 false false false 2 true true false false 3977000000 3977 [1] false false false xbrli:monetaryItemType monetary This item reflects the aggregate amount of assets measured at fair value on a recurring basis. 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No authoritative reference available. false 10 Assets 2 d_FairValueAssetsMeasuredOnRecurringBasisAbstract d false na duration Fair Value, Assets Measured on Recurring Basis [Abstract] false false false false false true false false false false false verboselabel false 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false xbrli:stringItemType string Fair Value, Assets Measured on Recurring Basis [Abstract] false 13 Total assets 2 d_FairValueAssetsMeasuredOnRecurringBasis d false debit instant This item reflects the aggregate amount of assets measured at fair value on a recurring basis. false false false false false false false false false false false totallabel false 1 false true false false 1976000000 1976 false false false 2 false true false false 1876000000 1876 [1] false false false xbrli:monetaryItemType monetary This item reflects the aggregate amount of assets measured at fair value on a recurring basis. No authoritative reference available. true 14 Liabilities 2 d_FairValueLiabilitiesMeasuredOnRecurringBasisAbstract d false na duration Fair Value, Liabilities Measured on Recurring Basis [Abstract] false false false false false true false false false false false verboselabel false 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false xbrli:stringItemType string Fair Value, Liabilities Measured on Recurring Basis [Abstract] false 16 Total liabilities 2 d_FairValueLiabilitiesMeasuredOnRecurringBasis d false credit instant This item reflects the aggregate amount of liabilities measured at fair value on a recurring basis. false false false false false false false false false false false totallabel false 1 false true false false 11000000 11 false false false 2 false true false false 17000000 17 false false false xbrli:monetaryItemType monetary This item reflects the aggregate amount of liabilities measured at fair value on a recurring basis. 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No authoritative reference available. false 18 Assets 2 d_FairValueAssetsMeasuredOnRecurringBasisAbstract d false na duration Fair Value, Assets Measured on Recurring Basis [Abstract] false false false false false true false false false false false verboselabel false 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false xbrli:stringItemType string Fair Value, Assets Measured on Recurring Basis [Abstract] false 19 Derivatives 2 us-gaap_FairValueAssetsMeasuredOnRecurringBasisDerivativeFinancialInstrumentsAssets us-gaap true debit instant No definition available. false false false false false false false false false false false verboselabel false 1 false true false false 87000000 87 false false false 2 false true false false 85000000 85 false false false xbrli:monetaryItemType monetary This element represents a certain statement of financial position asset caption which represents a class of assets, or which may include an individual asset, measured at fair value on a recurring basis. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 157 -Paragraph 32 -Subparagraph a false 22 Liabilities 2 d_FairValueLiabilitiesMeasuredOnRecurringBasisAbstract d false na duration Fair Value, Liabilities Measured on Recurring Basis [Abstract] false false false false false true false false false false false verboselabel false 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false xbrli:stringItemType string Fair Value, Liabilities Measured on Recurring Basis [Abstract] false 23 Derivatives 2 us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisDerivativeFinancialInstrumentsLiabilities us-gaap true credit instant No definition available. false false false false false false false false false false false verboselabel false 1 false true false false 11000000 11 false false false 2 false true false false 17000000 17 false false false xbrli:monetaryItemType monetary This element represents a certain statement of financial position liability caption which represents a class of liabilities, or which may include an individual liability, measured at fair value on a recurring basis. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 157 -Paragraph 32 -Subparagraph a false 25 Fair Value, Inputs, Level 1 | Equity Securities | United States | Large-Cap Value 0 na true na na No definition available. false true false false false false false false false false false http://www.dom.com/taxonomy/role/disclosureassetsandliabilitiesthataremeasuredatfairvalueonarecurringbasis false 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false false 7 USD true false false false Fair Value, Inputs, Level 1 d_FairValueAssetsAndLiabilitiesComponentsAxis xbrldi http://xbrl.org/2006/xbrldi us-gaap_FairValueInputsLevel1Member d_FairValueAssetsAndLiabilitiesComponentsAxis explicitMember false false Equity Securities us-gaap_DerivativeInstrumentsGainLossByDerivativeInstrumentRiskAxis xbrldi http://xbrl.org/2006/xbrldi us-gaap_EquitySecuritiesMember us-gaap_DerivativeInstrumentsGainLossByDerivativeInstrumentRiskAxis explicitMember false false United States us-gaap_FairValueByBalanceSheetGroupingDisclosureItemAmountsAxis xbrldi http://xbrl.org/2006/xbrldi d_UnitedStatesMember us-gaap_FairValueByBalanceSheetGroupingDisclosureItemAmountsAxis explicitMember false false Large-Cap Value us-gaap_ScheduleOfInvestmentIncomeReportedAmountsByCategoryAxis xbrldi http://xbrl.org/2006/xbrldi d_LargeCapValueMember us-gaap_ScheduleOfInvestmentIncomeReportedAmountsByCategoryAxis explicitMember iso4217_USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 $ false 8 USD true false false false Fair Value, Inputs, Level 1 d_FairValueAssetsAndLiabilitiesComponentsAxis xbrldi http://xbrl.org/2006/xbrldi us-gaap_FairValueInputsLevel1Member d_FairValueAssetsAndLiabilitiesComponentsAxis explicitMember false false Equity Securities us-gaap_DerivativeInstrumentsGainLossByDerivativeInstrumentRiskAxis xbrldi http://xbrl.org/2006/xbrldi us-gaap_EquitySecuritiesMember us-gaap_DerivativeInstrumentsGainLossByDerivativeInstrumentRiskAxis explicitMember false false United States us-gaap_FairValueByBalanceSheetGroupingDisclosureItemAmountsAxis xbrldi http://xbrl.org/2006/xbrldi d_UnitedStatesMember us-gaap_FairValueByBalanceSheetGroupingDisclosureItemAmountsAxis explicitMember false false Large-Cap Value us-gaap_ScheduleOfInvestmentIncomeReportedAmountsByCategoryAxis xbrldi http://xbrl.org/2006/xbrldi d_LargeCapValueMember us-gaap_ScheduleOfInvestmentIncomeReportedAmountsByCategoryAxis explicitMember iso4217_USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 $ na No definition available. No authoritative reference available. false 26 Assets 2 d_FairValueAssetsMeasuredOnRecurringBasisAbstract d false na duration Fair Value, Assets Measured on Recurring Basis [Abstract] false false false false false true false false false false false verboselabel false 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false xbrli:stringItemType string Fair Value, Assets Measured on Recurring Basis [Abstract] false 28 Investments 2 us-gaap_FairValueMeasuredOnRecurringBasisInvestments us-gaap true debit instant No definition available. false false false false false false false false false false false verboselabel false 1 false true false false 1547000000 1547 [1] false false false 2 false true false false 1520000000 1520 [1] false false false xbrli:monetaryItemType monetary This element represents a certain statement of financial position asset caption which represents a class of assets, or which may include an individual asset, measured at fair value on a recurring basis. 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No authoritative reference available. false 34 Assets 2 d_FairValueAssetsMeasuredOnRecurringBasisAbstract d false na duration Fair Value, Assets Measured on Recurring Basis [Abstract] false false false false false true false false false false false verboselabel false 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false xbrli:stringItemType string Fair Value, Assets Measured on Recurring Basis [Abstract] false 36 Investments 2 us-gaap_FairValueMeasuredOnRecurringBasisInvestments us-gaap true debit instant No definition available. false false false false false false false false false false false verboselabel false 1 false true false false 49000000 49 [1] false false false 2 false true false false 43000000 43 [1] false false false xbrli:monetaryItemType monetary This element represents a certain statement of financial position asset caption which represents a class of assets, or which may include an individual asset, measured at fair value on a recurring basis. 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No authoritative reference available. false 42 Assets 2 d_FairValueAssetsMeasuredOnRecurringBasisAbstract d false na duration Fair Value, Assets Measured on Recurring Basis [Abstract] false false false false false true false false false false false verboselabel false 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false xbrli:stringItemType string Fair Value, Assets Measured on Recurring Basis [Abstract] false 44 Investments 2 us-gaap_FairValueMeasuredOnRecurringBasisInvestments us-gaap true debit instant No definition available. false false false false false false false false false false false verboselabel false 1 false true false false 11000000 11 [1] false false false 2 false true false false 12000000 12 [1] false false false xbrli:monetaryItemType monetary This element represents a certain statement of financial position asset caption which represents a class of assets, or which may include an individual asset, measured at fair value on a recurring basis. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 157 -Paragraph 32 -Subparagraph a false 49 Fair Value, Inputs, Level 1 | Debt Securities | US Government Debt Securities 0 na true na na No definition available. false true false false false false false false false false false http://www.dom.com/taxonomy/role/disclosureassetsandliabilitiesthataremeasuredatfairvalueonarecurringbasis false 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false false 13 USD true false false false Fair Value, Inputs, Level 1 d_FairValueAssetsAndLiabilitiesComponentsAxis xbrldi http://xbrl.org/2006/xbrldi us-gaap_FairValueInputsLevel1Member d_FairValueAssetsAndLiabilitiesComponentsAxis explicitMember false false Debt Securities us-gaap_DerivativeInstrumentsGainLossByDerivativeInstrumentRiskAxis xbrldi http://xbrl.org/2006/xbrldi us-gaap_DebtSecuritiesMember us-gaap_DerivativeInstrumentsGainLossByDerivativeInstrumentRiskAxis explicitMember false false US Government Debt Securities us-gaap_FairValueByBalanceSheetGroupingDisclosureItemAmountsAxis xbrldi http://xbrl.org/2006/xbrldi us-gaap_USGovernmentDebtSecuritiesMember us-gaap_FairValueByBalanceSheetGroupingDisclosureItemAmountsAxis explicitMember iso4217_USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 $ false 14 USD true false false false Fair Value, Inputs, Level 1 d_FairValueAssetsAndLiabilitiesComponentsAxis xbrldi http://xbrl.org/2006/xbrldi us-gaap_FairValueInputsLevel1Member d_FairValueAssetsAndLiabilitiesComponentsAxis explicitMember false false Debt Securities us-gaap_DerivativeInstrumentsGainLossByDerivativeInstrumentRiskAxis xbrldi http://xbrl.org/2006/xbrldi us-gaap_DebtSecuritiesMember us-gaap_DerivativeInstrumentsGainLossByDerivativeInstrumentRiskAxis explicitMember false false US Government Debt Securities us-gaap_FairValueByBalanceSheetGroupingDisclosureItemAmountsAxis xbrldi http://xbrl.org/2006/xbrldi us-gaap_USGovernmentDebtSecuritiesMember us-gaap_FairValueByBalanceSheetGroupingDisclosureItemAmountsAxis explicitMember iso4217_USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 $ na No definition available. No authoritative reference available. false 50 Assets 2 d_FairValueAssetsMeasuredOnRecurringBasisAbstract d false na duration Fair Value, Assets Measured on Recurring Basis [Abstract] false false false false false true false false false false false verboselabel false 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false xbrli:stringItemType string Fair Value, Assets Measured on Recurring Basis [Abstract] false 52 Investments 2 us-gaap_FairValueMeasuredOnRecurringBasisInvestments us-gaap true debit instant No definition available. false false false false false false false false false false false verboselabel false 1 false true false false 274000000 274 [1] false false false 2 false true false false 216000000 216 [1] false false false xbrli:monetaryItemType monetary This element represents a certain statement of financial position asset caption which represents a class of assets, or which may include an individual asset, measured at fair value on a recurring basis. 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