Acquisitions and Dispositions (Schedule of Preliminary Allocation of Purchase Price to Assets Acquired and Liabilities Assumed) (Parenthetical) (Detail) - USD ($) $ in Millions		1 Months Ended	12 Months Ended
		Jan. 31, 2019	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Business Acquisition [Line Items]
Cash, restricted cash and equivalents			$ 408	$ 247	$ 269	$ 391
Impairment of assets and other charges			$ 195	2,105	1,520
Intangible assets, estimated weighted-average amortization period			7 years
Repayment of letter of credit advances			$ 225
Pension and other postretirement benefit liability			442	1,706
SCANA
Business Acquisition [Line Items]
Cash, restricted cash and equivalents					389
Restricted cash					115
Equity method investment					31
Property, plant and equipment	[1],[2]				11,006
Impairment of assets and other charges			100	90	641
Impairment of assets and other charges, after tax			$ 75	$ 68	$ 480
Intangible assets, estimated weighted-average amortization period					5 years
Repayment of letter of credit advances		$ 40
Repayments of Commercial Paper		$ 173
Pension and other postretirement benefit liability					$ 379
Stock based compensation awards estimated fair value					$ 21
SCANA | Minimum
Business Acquisition [Line Items]
Property, plant and equipment, estimated useful lives					5 years
SCANA | Maximum
Business Acquisition [Line Items]
Property, plant and equipment, estimated useful lives					78 years
SCANA | NND Project
Business Acquisition [Line Items]
Property, plant and equipment					$ 105
Impairment of assets and other charges					105
Impairment of assets and other charges, after tax					79
SCANA | Dominion Energy South Carolina Inc | NND Project
Business Acquisition [Line Items]
Income tax regulatory assets					$ 258

[1] Includes $105 million of certain property, plant and equipment associated with the NND Project for which Dominion Energy committed to forgo recovery in accordance with the SCANA Merger Approval Order. As a result, Dominion Energy’s Consolidated Statements of Income for the year ended December 31, 2019 include a charge of $105 million ($79 million after-tax), included in impairment of assets and other charges (reflected in the Corporate and Other segment).

[2] Nonregulated property, plant and equipment, excluding land, will be depreciated on a straight-line basis over the remaining useful lives of such property, primarily ranging from 5 to 78 years.