XML 154 R144.htm IDEA: XBRL DOCUMENT
v3.8.0.1

Employee Benefit Plans (Fair values of pension and post retirement plan assets by asset category) (Parenthetical) (Detail) - Collective Bargaining Agreement - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2017 | Dec. 31, 2016
Pension Benefits |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Pending sales of securities | $ 11 | $ 46
Net accrued income | 19 | 19
Pending purchases of securities | 15 | 47
Other Postretirement Benefits |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Pending sales of securities | 1 | 5
Net accrued income | 2 | 2
Pending purchases of securities | 1 | 5
Dominion Energy Gas Holdings, LLC | Pension Benefits |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Pending sales of securities | 3 | 10
Net accrued income | 4 | 4
Pending purchases of securities | $ 3 | $ 10

X
- Definition Defined benefit plan, net accrued income. + References No definition available. + Details
Name: | d_DefinedBenefitPlanNetAccruedIncome
Namespace Prefix: | d_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Defined Benefit Plan, Pending Purchases of Securities + References No definition available. + Details
Name: | d_DefinedBenefitPlanPendingPurchasesOfSecurities
Namespace Prefix: | d_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Defined benefit plan, pending sales of securities. + References No definition available. + Details
Name: | d_DefinedBenefitPlanPendingSalesofSecurities
Namespace Prefix: | d_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_DefinedBenefitPlanDisclosureLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_CollectiveBargainingArrangementAxis=d_CollectiveBargainingAgreementMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RetirementPlanTypeAxis=us-gaap_PensionPlansDefinedBenefitMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RetirementPlanTypeAxis=us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=d_DominionEnergyGasHoldingsLLCMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |