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Employee Benefit Plans (Benefit Payments Expected Future Service) (Detail) $ in Millions | Dec. 31, 2017 USD ($)
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Pension Benefits |
Defined Benefit Plan Disclosure [Line Items] |
2018 | $ 373
2019 | 378
2020 | 402
2021 | 418
2022 | 434
2023-2027 | 2,437
Pension Benefits | Dominion Energy Gas Holdings, LLC |
Defined Benefit Plan Disclosure [Line Items] |
2018 | 35
2019 | 37
2020 | 38
2021 | 39
2022 | 41
2023-2027 | 214
Other Postretirement Benefits |
Defined Benefit Plan Disclosure [Line Items] |
2018 | 99
2019 | 101
2020 | 102
2021 | 102
2022 | 102
2023-2027 | 486
Other Postretirement Benefits | Dominion Energy Gas Holdings, LLC |
Defined Benefit Plan Disclosure [Line Items] |
2018 | 19
2019 | 19
2020 | 20
2021 | 20
2022 | 20
2023-2027 | $ 94

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