Acquisitions and Dispositions (Schedule of Acquisitions of Solar Projects) (Parenthetical) (Detail)	1 Months Ended
Apr. 30, 2017 MW
Business Combinations Discontinued Operations And Disposal Groups [Abstract]
Discontinued efforts on acquisition of additional MW capacity	20

Additional capacity of facility of company owned solar distribution generation facilities in which acquisition efforts were discontinued.

No definition available.

Name:	d_AdditionalCapacityOfFacilityOfCompanyOwnedSolarDistributionGenerationFacilitiesInWhichAcquisitionEffortsWereDiscontinued
Namespace Prefix:	d_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	duration