Commitments and Contingencies (Narrative) (Detail) shares in Millions	1 Months Ended													3 Months Ended		12 Months Ended
	Mar. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)	Jul. 31, 2023 USD ($)	Sep. 30, 2022 USD ($)	Jun. 30, 2022 USD ($)	May 31, 2022 shares	Aug. 31, 2021 shares	Jun. 30, 2021 USD ($)	Dec. 31, 2020 USD ($)	Oct. 31, 2020	Jun. 30, 2018 USD ($)	Apr. 30, 2017 Petition	Aug. 31, 2016 T	Mar. 31, 2024 USD ($) Indicator Facility Site gal	Mar. 31, 2023 USD ($)	Dec. 31, 2023 USD ($)	Jun. 30, 2023 USD ($)	Dec. 31, 2022 USD ($)
Loss Contingencies [Line Items]
Gain on sales of assets														$ 1,000,000	$ 2,000,000
Gain on sales of assets after tax														$ 560,000,000	700,000,000
Nuclear Obligations | Secondary Financial Protection Program
Loss Contingencies [Line Items]
Maximum liability protection per nuclear incident amount	$ 16,300,000,000	$ 16,200,000,000
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					$ 51,000,000				$ 165,000,000
Proposed assessment amount from audit											$ 410,000,000
Proportional share of NND project											100.00%
Fair value of certain non-utility property transferred				$ 28,000,000
Fair value of utility property transferred															10,000,000
Gain upon completion of remaining transfer of utility properties																	$ 11,000,000
Fair value of additional utility property transferred																		$ 3,000,000
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 | Utility Property Transferred | SCDOR
Loss Contingencies [Line Items]
Gain on sales of assets															9,000,000
Gain on sales of assets after tax															$ 7,000,000
Dominion Energy South Carolina Inc | Minimum | SCDOR
Loss Contingencies [Line Items]
Initial litigation settlement amount through stock issuance								$ 43,000,000
Dominion Energy South Carolina Inc | Maximum | SCDOR
Loss Contingencies [Line Items]
Cash payment for remaining obligation			$ 1,000,000
Unfavorable Regulatory Action | EPA
Loss Contingencies [Line Items]
Electric generating station facilities water withdrawals per day | gal														2,000,000
Electric generating station facilities heightened entrainment analysis per day | gal														125,000,000
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 | 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														11
Number of additional sites which are not under investigation | Site														3
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														$ 31,000,000		$ 32,000,000
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														$ 25,000,000		25,000,000
Millstone, Summer, Surry and North Anna
Loss Contingencies [Line Items]
Amount of coverage purchased from commercial insurance pools	$ 500,000,000	$ 450,000,000												$ 500,000,000		$ 450,000,000