Leases (Narrative) (Detail) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
	Jul. 31, 2016	Sep. 30, 2019		Sep. 30, 2019		Dec. 31, 2018	[1]
Leases Disclosure [Line Items]
Property, plant and equipment, net		$ 67,978		$ 67,978		$ 54,560
Accumulated depreciation, depletion and amortization		28,144		28,144		$ 22,018
Lease, term of commenced	5 years
Right-of-use asset	$ 67	159	[2]	159	[2]
Offsetting lease obligation	$ 67	162		162
Corporate office | Agreement with Lessor to Construct and Lease Corporate Office Property
Leases Disclosure [Line Items]
Extension term of lease	5 years
Required percentage payment to lessor for difference between project costs and sales proceeds	87.00%
Lessor | Corporate office | Agreement with Lessor to Construct and Lease Corporate Office Property
Leases Disclosure [Line Items]
Amount of financing commitments to fund estimated project costs	$ 365
Power Purchase Arrangements
Leases Disclosure [Line Items]
Property, plant and equipment, net		2,800		2,800
Accumulated depreciation, depletion and amortization		341		341
Rental revenue		64		146
Depreciation expense		$ 23		$ 70

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

[2] Included in property, plant and equipment in the Companies’ Consolidated Balance Sheets, net of $39 million, $3 million and $1 million of accumulated amortization at Dominion Energy, Virginia Power and Dominion Energy Gas, respectively, at September 30, 2019.