Operating Segments (Narrative) (Detail) - Operating Segments - USD ($) $ in Millions	6 Months Ended
Jun. 30, 2018	Jun. 30, 2017
Segment Reporting Information [Line Items]
After- tax net expenses	$ (310)	$ (1)
Virginia Electric and Power Company
Segment Reporting Information [Line Items]
After- tax net expenses	(230)
Dominion Energy Gas Holdings, LLC
Segment Reporting Information [Line Items]
After- tax net expenses	(89)
Disallowance charge	122
Disallowance charge, after tax	89
Write off of regulatory asset		15
Write off of regulatory asset, after tax		9
Virginia Regulation
Segment Reporting Information [Line Items]
Charge associated with legislation enacted	215
Charge associated with legislation enacted, after tax	160
Virginia Regulation \| Virginia Electric and Power Company
Segment Reporting Information [Line Items]
Charge associated with legislation enacted	215
Charge associated with legislation enacted, after tax	160
Corporate and Other
Segment Reporting Information [Line Items]
After- tax net expenses	(349)	(10)
Corporate and Other \| Virginia Electric and Power Company
Segment Reporting Information [Line Items]
After- tax net expenses	(237)	(7)
Corporate and Other \| Dominion Energy Gas Holdings, LLC
Segment Reporting Information [Line Items]
After- tax net expenses	(91)	$ (9)
Power Generation \| Virginia Regulation
Segment Reporting Information [Line Items]
Charge associated with legislation enacted, after tax	109
Power Generation \| Virginia Regulation \| Virginia Electric and Power Company
Segment Reporting Information [Line Items]
Charge associated with legislation enacted, after tax	109
Power Generation \| Virginia Legislation \| Virginia Electric and Power Company
Segment Reporting Information [Line Items]
Asset retirement obligations	81
Asset retirement obligations, after tax	60
Power Generation \| Ash Ponds and Landfills Certain Utility Generation Facility \| Virginia Legislation
Segment Reporting Information [Line Items]
Asset retirement obligations	81
Asset retirement obligations, after tax	60
Power Delivery \| Virginia Electric and Power Company
Segment Reporting Information [Line Items]
Customer settlement	16
Customer settlement, after tax	10
Power Delivery \| Virginia Regulation
Segment Reporting Information [Line Items]
Charge associated with legislation enacted, after tax	51
Power Delivery \| Virginia Regulation \| Virginia Electric and Power Company
Segment Reporting Information [Line Items]
Charge associated with legislation enacted, after tax	51
Gas Infrastructure \| Federal Energy Regulatory Commission
Segment Reporting Information [Line Items]
Disallowance charge	122
Disallowance charge, after tax	$ 89

Asset retirement obligation accretion expense After tax.

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- Definition

Disallowance charge.

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No definition available.

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- Definition

Disallowance charge after tax.

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- Definition

Legislation charge.

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- Definition

Legislation charge after tax.

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- Definition

Rental settlement charges.

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- Definition

Write off of regulatory asset.

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- Definition

Write off of regulatory asset net of tax.

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- Definition

Amount of accretion expense recognized during the period that is associated with an asset retirement obligation. Accretion expense measures and incorporates changes due to the passage of time into the carrying amount of the liability.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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-Topic 410
-SubTopic 20
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- Definition

The aggregate amount of income or expense from ancillary business-related activities (that is to say, excluding major activities considered part of the normal operations of the business).

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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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.

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