Asset Retirement Obligations (Changes to AROs) (Detail) $ in Millions	9 Months Ended
	Sep. 30, 2019 USD ($)
Asset Retirement Obligations [Line Items]
AROs, Beginning balance	$ 2,532	[1]
Obligations incurred during the period	2,404	[2]
Obligations settled during the period	(100)
AROs acquired in the SCANA Combination	577
Revisions in estimated cash flows	(229)	[2]
Accretion	153
AROs, Ending balance	5,337	[1]
Virginia Electric and Power Company
Asset Retirement Obligations [Line Items]
AROs, Beginning balance	1,445	[3]
Obligations incurred during the period	2,403	[2]
Obligations settled during the period	(60)
Revisions in estimated cash flows	(202)	[2]
Accretion	94
AROs, Ending balance	3,680	[3]
Dominion Energy Gas Holdings, LLC
Asset Retirement Obligations [Line Items]
AROs, Beginning balance	167	[4]
Obligations settled during the period	(6)
Revisions in estimated cash flows	(26)
Accretion	7
AROs, Ending balance	$ 142	[4]

[1] Includes $282 million and $317 million reported in other current liabilities at December 31, 2018 and September 30, 2019, respectively.

[2] Primarily related to future ash pond and landfill closure costs at certain utility generation facilities. See Note 18 for further information.

[3] Includes $245 million and $262 million reported in other current liabilities at December 31, 2018 and September 30, 2019, respectively.

[4] Includes $153 million and $134 million reported in other deferred credits and other liabilities, with the remainder recorded in other current liabilities, at December 31, 2018 and September 30, 2019, respectively.