Acquisitions and Dispositions (Acquisition Of Scana) (Narrative) (Detail) - USD ($) $ in Millions		1 Months Ended	2 Months Ended	3 Months Ended									12 Months Ended
	Sep. 16, 2016	Jan. 31, 2019	Oct. 31, 2017	Dec. 31, 2019		Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019		Dec. 31, 2018	Dec. 31, 2017
Business Acquisition And Dispositions [Line Items]
Stock issued during period for acquisition, value		$ 1,600											$ 6,818
Regulatory Liabilities				$ 11,498					$ 7,196				11,498		$ 7,196
Regulatory liabilities-current				497					356				497		356
After tax charge in statements of income				1,009		$ 975	$ 54	$ (680)	$ 641	$ 854	$ 449	$ 503	1,358		$ 2,447	$ 2,999
SCANA
Other Commitment, Fiscal Year Maturity [Abstract]
Charitable contributions, annual committed increase for next five years													$ 1
SCANA | Minimum
Other Commitment, Fiscal Year Maturity [Abstract]
Charitable contributions, period committed for annual increase	5 years
SCANA
Business Acquisition And Dispositions [Line Items]
Stock issued during period for acquisition, shares		95,600,000											95,600,000
Stock issued during period for acquisition, value		$ 6,800											$ 6,800
Common stock agreed to issue		0.669%
Total outstanding debt		$ 6,900		6,707									6,707
Business combination, refund to customers		$ 2,000
Period to provide refund to customer		20 years	20 years					11 years
Regulatory Liabilities			$ 1,100
Regulatory liabilities-current			67					$ 137
Refund Liability to electric service customers			1,000
Reduction in operating revenue								$ 1,000
After tax charge in statements of income													756
Business combination cost related to exclusion from rate recovery		$ 2,400
Remaining regulatory asset		2,800		$ 3,940	[1]								$ 3,940	[1]
Remaining regulatory asset current		138
SCANA | Toshiba Corporation
Business Acquisition And Dispositions [Line Items]
Cash consideration			$ 1,100
SCANA | Columbia Energy
Business Acquisition And Dispositions [Line Items]
Business combination cost related to exclusion from rate recovery		$ 180

[1] Includes $258 million of certain income tax-related regulatory assets associated with the NND Project for which Dominion Energy committed to forgo recovery in accordance with the SCANA Merger Approval Order. See Note 5 for additional information.