Commitments and Contingencies (Narrative) (Detail) shares in Millions, $ in Millions	1 Months Ended											3 Months Ended			9 Months Ended		12 Months Ended
	Sep. 30, 2022 USD ($)	Jun. 30, 2022 USD ($) shares	May 31, 2022 shares	Aug. 31, 2021 shares	Jun. 30, 2021 USD ($)	Dec. 31, 2020 USD ($)	Oct. 31, 2020	Jun. 30, 2018 USD ($)	Aug. 31, 2017 USD ($)	Apr. 30, 2017 Petition	Aug. 31, 2016 T	Sep. 30, 2022 USD ($)	Jun. 30, 2022 site	Sep. 30, 2021 USD ($)	Sep. 30, 2022 USD ($) Indicator Facility site gal	Sep. 30, 2021 USD ($)	Dec. 31, 2021 USD ($)
Loss Contingencies [Line Items]
Gain on sales of assets												$ 27		$ 3	$ (581)	$ 2
Gain on sales of assets after tax												781		$ 601	1,021	1,850
SCANA
Loss Contingencies [Line Items]
Impairment of assets and other charges																100
Impairment of assets and other charges, after tax																$ 75
Utilization of insurance proceeds for settlements.		$ 33
Litigation settlement amount through stock issuance | shares		0.4
Cash payment		$ 2
SCANA | State Court Derivative Case
Loss Contingencies [Line Items]
Litigation settlement paid					$ 33
SCANA | Federal Court Merger Case | State Court Merger Case
Loss Contingencies [Line Items]
Litigation settlement paid					63
SCANA | Other Current Liabilities
Loss Contingencies [Line Items]
Reserves for SCANA legal proceedings	$ 96											96			96		$ 274
SCANA | Other Receivables
Loss Contingencies [Line Items]
Insurance receivables	68											68			$ 68		118
Virginia Electric and Power Company | EPA and State Regulatory Agencies
Loss Contingencies [Line Items]
Number of facilities to assess the applicability of section 316(b) | Facility															3
Hydroelectric Facilities | EPA and State Regulatory Agencies
Loss Contingencies [Line Items]
Number of facilities to assess the applicability of section 316(b) | Facility															8
Dominion Energy South Carolina Inc | SCDOR
Loss Contingencies [Line Items]
Litigation settlement paid		$ 51				$ 165
Proposed assessment amount from audit								$ 410
Proportional share of NND project								100.00%
Gain on expected conveyed value of utility and non-utility properties upon approval															$ 20
Non-utility property with fair value	28
Gain on sales of assets	18
Certain additional utility property	3											3			$ 3
Gain on sales of assets after tax	14
Dominion Energy South Carolina Inc | South Carolina
Loss Contingencies [Line Items]
Amount claimed by plaintiffs in legal matter									$ 100
Percentage claimed by plaintiffs in legal matter									100.00%
Dominion Energy South Carolina Inc | DESC | SCDOR | Common Stock
Loss Contingencies [Line Items]
Initial litigation settlement through stock issuance | shares			0.9	0.6
Dominion Energy South Carolina Inc | Minimum | SCDOR
Loss Contingencies [Line Items]
Initial litigation settlement amount through stock issuance					$ 43
Unfavorable Regulatory Action | EPA
Loss Contingencies [Line Items]
Electric generating station facilities heightened entrainment analysis per day | gal															125,000,000
Personal Injury or Wrong Death Cases | SCANA
Loss Contingencies [Line Items]
Reserves for SCANA legal proceedings	68											68			$ 68		85
Insurance receivables	$ 68											$ 68			$ 68		85
Carbon Regulations
Loss Contingencies [Line Items]
Public Utilities Significant Emission Rate Per Year CO2 Equivalent | T											75,000
CWA | Unfavorable Regulatory Action
Loss Contingencies [Line Items]
Number of mandatory facility-specific factors | Indicator															5
Number of optional facility-specific factors | Indicator															6
Number of facilities that are subject to final regulations | Facility															15
CWA | Unfavorable Regulatory Action | Minimum
Loss Contingencies [Line Items]
Electric generating stations with water withdrawals per day | gal															2,000,000
CWA | Unfavorable Regulatory Action | EPA | Final Rule to Revise Effluent Limitations Guidelines for Steam Electric Power Generating Category
Loss Contingencies [Line Items]
Number of separate petitions for reconsideration granted | Petition										2
CWA | Unfavorable Regulatory Action | EPA | Minimum | Final Rule to Revise Effluent Limitations Guidelines for Steam Electric Power Generating Category
Loss Contingencies [Line Items]
Loss contingencies individual circumstances period							2021
CWA | Unfavorable Regulatory Action | EPA | Maximum | Final Rule to Revise Effluent Limitations Guidelines for Steam Electric Power Generating Category
Loss Contingencies [Line Items]
Loss contingencies individual circumstances period							2028
CWA | Unfavorable Regulatory Action | Virginia Electric and Power Company
Loss Contingencies [Line Items]
Number of facilities that are subject to final regulations | Facility															9
Waste Management and Remediation | Unfavorable Regulatory Action | EPA
Loss Contingencies [Line Items]
Number of sites remediation work substantially completed | site															13
Number of sites with remediation plans | site													1
Number of additional sites which are not under investigation | site															12
Waste Management and Remediation | Unfavorable Regulatory Action | EPA | Former Gas Plant Site With Post Closure Groundwater Monitoring Program
Loss Contingencies [Line Items]
Environmental remediation reserves															$ 47		45
Waste Management and Remediation | Unfavorable Regulatory Action | Virginia Electric and Power Company | EPA
Loss Contingencies [Line Items]
Number of sites with remediation plans | site															1
Number of additional sites which are not under investigation | site															2
Waste Management and Remediation | Unfavorable Regulatory Action | Virginia Electric and Power Company | EPA | Former Gas Plant Site With Post Closure Groundwater Monitoring Program
Loss Contingencies [Line Items]
Environmental remediation reserves															$ 25		$ 25