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Employee Benefit Plans (Benefit Obligation in Excess of Plan Assets) (Detail) - USD ($) $ in Millions | Dec. 31, 2018 | Dec. 31, 2017
--- | --- | ---
Pension Benefits |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Benefit obligation | $ 7,705 | $ 8,209
Fair value of plan assets | 5,398 | 6,103
Other Postretirement Benefits |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Benefit obligation | 164 | 191
Fair value of plan assets | 136 | 156
Other Postretirement Benefits | Dominion Energy Gas Holdings, LLC |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Benefit obligation | 134 | 157
Fair value of plan assets | $ 126 | $ 143

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- Definition Amount of accumulated benefit obligation for defined benefit pension plan with projected benefit obligation in excess of plan assets. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 3 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=108410482&loc=d3e2417-114920 + Details
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- Definition Amount of plan asset for defined benefit pension plan with projected benefit obligation in excess of plan assets. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 3 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=108410482&loc=d3e2417-114920 + Details
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