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Employee Benefit Plans (Components of AOCI and Regulatory Assets and Liabilities) (Detail) $ in Millions | Dec. 31, 2018 USD ($)
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Pension Benefits |
Defined Benefit Plan Disclosure [Line Items] |
Net actuarial loss | $ 155
Prior service (credit) cost | 1
Pension Benefits | Dominion Energy Gas Holdings, LLC |
Defined Benefit Plan Disclosure [Line Items] |
Net actuarial loss | 19
Other Postretirement Benefits |
Defined Benefit Plan Disclosure [Line Items] |
Net actuarial loss | 18
Prior service (credit) cost | (52)
Other Postretirement Benefits | Dominion Energy Gas Holdings, LLC |
Defined Benefit Plan Disclosure [Line Items] |
Net actuarial loss | 4
Prior service (credit) cost | $ (4)

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