Variable Interest Entities (Narrative) (Detail) $ in Millions	1 Months Ended	3 Months Ended		6 Months Ended
	May 31, 2019 USD ($)	Jun. 30, 2019 USD ($)	Jun. 30, 2018 USD ($)	Jun. 30, 2019 USD ($) MW Generator	Jun. 30, 2018 USD ($)	Dec. 31, 2018 USD ($)
Virginia Electric and Power Company
Variable Interest Entity [Line Items]
Securities due within one year		$ 2		$ 2		$ 350	[1]
Long term debt		11,291		11,291		11,321	[1]
Payables to affiliates		182		182		209	[1]
Dominion Energy Gas Holdings, LLC
Variable Interest Entity [Line Items]
Securities due within one year		451		451		449	[2]
Long term debt		3,614		3,614		3,609	[2]
Payables to affiliates		43		43		65	[2]
Variable Interest Entity, Primary Beneficiary | SBL Holdco
Variable Interest Entity [Line Items]
Securities due within one year		32		32		31
Long term debt		290		$ 290		299
Variable Interest Entity (VIE) or Potential VIE, Information Unavailability | Virginia Electric and Power Company
Variable Interest Entity [Line Items]
Long term capacity contract non utility generators (generators) | Generator				1
Aggregate generation capacity from long-term power and capacity contracts (MW) | MW				218
Payment for contract termination	$ 135	135		$ 135
Payment for contract termination after tax		100		100
Payment for electric capacity			$ 12	13	$ 25
Payment for electric energy			5	1	10
Variable Interest Entity, Not Primary Beneficiary | Virginia Electric and Power Company | DES
Variable Interest Entity [Line Items]
Shared services purchased		129	83	218	172
Payables to affiliates		92		92		107
Variable Interest Entity, Not Primary Beneficiary | Dominion Energy Gas Holdings, LLC | DES
Variable Interest Entity [Line Items]
Shared services purchased		50	$ 31	85	$ 63
Payables to affiliates		$ 39		$ 39		$ 46

[1] Virginia Power’s Consolidated Balance Sheet at December 31, 2018 has been derived from the audited Consolidated Balance Sheet at that date.

[2] Dominion Energy Gas’ Consolidated Balance Sheet at December 31, 2018 has been derived from the audited Consolidated Balance Sheet at that date.