DOMINION ENERGY SOUTH CAROLINA, INC., 10-K filed on 2/27/2025
Annual Report
v3.25.0.1
Document and Entity Information - shares
 12 Months Ended
Dec. 31, 2024
Feb. 20, 2025
Cover [Abstract]    
Document Type 10-K  
Amendment Flag false  
Document Period End Date Dec. 31, 2024  
Document Fiscal Year Focus 2024  
Document Fiscal Period Focus FY  
Title of 12(g) Security Series A Nonvoting Preferred Shares  
Document Annual Report true  
Document Transition Report false  
Entity Interactive Data Current Yes  
Entity Incorporation, State or Country Code SC  
Entity Registrant Name DOMINION ENERGY SOUTH CAROLINA, INC.  
Entity Central Index Key 0000091882  
Current Fiscal Year End Date --12-31  
Entity Filer Category Non-accelerated Filer  
Entity Small Business false  
Entity Emerging Growth Company false  
Entity Common Stock, Shares Outstanding   40,296,147
Entity Current Reporting Status Yes  
Document Financial Statement Error Correction [Flag] false  
Entity Shell Company false  
Entity File Number 001-3375  
Entity Tax Identification Number 57-0248695  
Entity Address, Address Line One 220 OPERATION WAY  
Entity Address, City or Town CAYCE  
Entity Address, State or Province SC  
Entity Address, Postal Zip Code 29033  
City Area Code 804  
Local Phone Number 819-2284  
Entity Well-known Seasoned Issuer No  
Entity Voluntary Filers No  
ICFR Auditor Attestation Flag false  
Auditor Name Deloitte & Touche LLP  
Auditor Location Richmond, Virginia  
Auditor Firm ID 34  
Auditor Opinion

Opinion on the Consolidated Financial Statements

We have audited the accompanying consolidated balance sheets of Dominion Energy South Carolina, Inc. (an indirect, wholly-owned subsidiary of Dominion Energy, Inc.) and affiliates (“DESC”) at December 31, 2024 and 2023, the related consolidated statements of comprehensive income, changes in common equity, and cash flows, for each of the three years in the period ended December 31, 2024, and the related notes (collectively referred to as the "consolidated financial statements"). In our opinion, the consolidated financial statements present fairly, in all material respects, the financial position of DESC at December 31, 2024 and 2023, and the results of its operations and its cash flows for each of the three years in the period ended December 31, 2024, in conformity with accounting principles generally accepted in the United States of America.

  
v3.25.0.1
Consolidated Balance Sheets - USD ($)
$ in Millions
Dec. 31, 2024
Dec. 31, 2023
ASSETS    
Utility plant in service $ 16,300 $ 15,500
Accumulated depreciation and amortization (5,761) (5,557)
Construction work in progress 899 606
Nuclear fuel, net of accumulated amortization 224 229
Utility plant, net 11,662 10,778
Nonutility Property and Investments:    
Nonutility property, net of accumulated depreciation 16 24
Assets held in trust, nuclear decommissioning 268 247
Nonutility property and investments, net 284 271
Current Assets:    
Cash and cash equivalents 0 1
Customer, net of allowance for uncollectible accounts of $6 for both periods 423 420
Receivables, other 104 97
Inventories (at average cost):    
Fuel 83 94
Gas storage 22 30
Materials and supplies 211 232
Prepayments 91 84
Derivative assets [1] 63 9
Regulatory assets 299 444
Other current assets 16 14
Total current assets 1,316 1,429
Deferred Debits and Other Assets:    
Derivative assets [1] 309 167
Regulatory assets 3,342 3,107
Affiliated receivables 26 4
Other 102 101
Total deferred debits and other assets 3,779 3,379
Total assets 17,041 15,857
CAPITALIZATION AND LIABILITIES    
Common Stock - no par value 4,088 4,088
Retained earnings 689 592
Accumulated other comprehensive loss (1) (1)
Total common equity 4,776 4,679
Noncontrolling interest 206 183
Total equity 4,982 4,862
Long-term debt, net 4,220 4,219
Affiliated long-term debt 230 0
Finance leases 2 4
Total long-term debt 4,452 4,223
Total capitalization 9,434 9,085
Current Liabilities:    
Short-term borrowings 250 254
Securities due within one year 2 3
Accounts payable 273 180
Affiliated and related party payables 995 740
Customer deposits and customer prepayments 82 75
Taxes accrued 254 248
Interest accrued 83 79
Regulatory liabilities 201 205
Reserves for litigation and regulatory proceedings 7 3
Other 194 163
Total current liabilities 2,341 1,950
Deferred Credits and Other Liabilities:    
Deferred income taxes and investment tax credits 1,409 1,318
Asset retirement obligations 1,139 731
Pension and other postretirement benefits 109 115
Derivative liabilities 1 4
Regulatory liabilities 2,488 2,579
Other 120 75
Total deferred credits and other liabilities 5,266 4,822
Commitments and Contingencies
Total capitalization and liabilities 17,041 15,857
Related Party    
Current Assets:    
Affiliated and related party $ 4 $ 4
[1] See Note 16 for amounts attributable to affiliates.
v3.25.0.1
Consolidated Balance Sheets (Parenthetical) - USD ($)
shares in Millions, $ in Millions
Dec. 31, 2024
Dec. 31, 2023
Utility plant, net $ 11,662 $ 10,778
Receivables, customer, allowance for uncollectible accounts 6 6
Total current assets 1,316 1,429
Total deferred debits and other assets $ 3,779 $ 3,379
Common stock, par value $ 0 $ 0
Common stock, shares outstanding 40.3 40.3
Variable Interest Entity, Primary Beneficiary [Member]    
Utility plant, net $ 824 $ 773
Total current assets 79 89
Total deferred debits and other assets $ 25 $ 26
v3.25.0.1
Consolidated Statements of Comprehensive Income - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2024
Dec. 31, 2023
Dec. 31, 2022
Income Statement [Abstract]      
Operating Revenue [1] $ 3,173 $ 3,028 $ 3,783
Operating Expenses:      
Fuel used in electric generation [2] 603 582 1,000
Purchased power [1],[2] 68 72 137
Gas purchased for resale [2] 245 243 433
Other operations and maintenance 492 436 460
Other operations and maintenance – affiliated suppliers 165 163 164
Impairment of assets and other charges 60 3 6
Depreciation and amortization [2] 546 531 507
Other taxes [1],[2] 300 292 277
Total operating expenses 2,479 2,322 2,984
Operating income 694 706 799
Other income (expense), net [3] (1) 24 55
Interest charges, net of AFUDC [1] 276 250 220
Income before income tax expense 417 480 634
Income tax expense [2] 65 85 131
Net Income 352 395 503
Other Comprehensive Income (Loss):      
Deferred cost of employee benefit plans, net of tax [3] 0 1 (1)
Total Comprehensive Income 352 396 502
Comprehensive Income Attributable to Noncontrolling Interest [3] 23 21 20
Comprehensive Income (Loss) Available (Attributable) to Common Shareholder $ 329 $ 375 $ 482
[1] See Note 16 for amounts attributable to affiliates.
[2] The significant expense categories and amounts in the segment information presented above align with the segment-level information that is regularly provided to DESC’s CODM.
[3] Items designated are other segment items for each reportable segment.
v3.25.0.1
Consolidated Statements of Comprehensive Income (Parenthetical) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2024
Dec. 31, 2023
Dec. 31, 2022
Income Statement [Abstract]      
Allowance for funds used during construction $ 25 $ 20 $ 7
v3.25.0.1
Consolidated Statements of Cash Flows - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2024
Dec. 31, 2023
Dec. 31, 2022
Operating Activities      
Net income $ 352 $ 395 $ 503
Adjustments to reconcile net income to net cash provided by operating activities:      
Impairment of assets and other charges 60 3 4
Deferred income taxes, net 91 88 255
Depreciation and amortization 546 531 507
Amortization of nuclear fuel 34 33 39
Other adjustments 4 (21) (33)
Changes in certain assets and liabilities:      
Receivables (21) 5 (72)
Receivables – affiliated and related party 0 (2) 14
Inventories (10) (2) (83)
Prepayments and deposits, net 0 (12) 0
Regulatory assets 79 334 (532)
Regulatory liabilities (94) (301) (94)
Accounts payable 68 (68) 52
Accounts payable – affiliated and related party (14) (35) 59
Interest accrued 4 4 2
Taxes accrued 6 12 14
Net realized and unrealized changes related to commodity derivative activities (194) 75 (103)
Pension and other postretirement benefits (6) 2 (50)
Other assets and liabilities 16 (22) 24
Net cash provided by operating activities 921 1,019 506
Investing Activities      
Property additions and construction expenditures (1,105) (957) (697)
Proceeds from investments and sales or disposals of assets, including asset retirement costs (54) (42) (19)
Purchase of investments (26) (4) (5)
Other 2 5 6
Net cash used in investing activities (1,183) (998) (715)
Financing Activities      
Proceeds from issuance of debt 0 500 0
Dividend to parent (232) (200) (433)
Short-term borrowings, net (4) 5 249
Short-term borrowings – affiliated, net 499 (326) 354
Other (2) (10) (4)
Net cash provided by (used in) financing activities 261 (31) 166
Net decrease in cash, restricted cash and equivalents (1) (10) (43)
Cash, restricted cash and equivalents at beginning of period 1 11 54
Cash, restricted cash and equivalents at end of period 0 1 11
Supplemental Cash Flow Information      
Interest paid (net of capitalized interest of $25, $20 and $7) [1] 211 176 190
Income taxes paid 23 69 0
Income taxes received 0 0 130
Noncash investing and financing activities:      
Accrued construction expenditures [2] 138 116 126
Operating leases [2],[3] 5 2 6
Contributed capital [2] $ 0 $ 0 $ 72
[1] Excludes amounts related to affiliated debt discussed in Note 6.
[2] See Note 5 for noncash financing activities related to capital contributions associated with the settlement of litigation. See Note 12 for noncash investing activities related to the transfer of property associated with the settlement of litigation.
[3] Finance leases entered into, if any, were inconsequential for all years presented.
v3.25.0.1
Consolidated Statements of Cash Flows (Parenthetical) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2024
Dec. 31, 2023
Dec. 31, 2022
Statement of Cash Flows [Abstract]      
Cash paid for interest, capitalized interest $ 25 $ 20 $ 7
v3.25.0.1
Consolidated Statements of Changes in Common Equity - USD ($)
shares in Millions, $ in Millions
Total
Common Stock
Retained Earnings
AOCI
Non-controlling Interest
Beginning balance at Dec. 31, 2021 $ 4,525 $ 4,016 $ 335 $ (1) $ 175
Beginning balance (in shares) at Dec. 31, 2021   40      
Total comprehensive income available to common shareholder 502   483 (1) 20
Capital contribution from parent 72 $ 72      
Dividend to parent (433)   (400)   (33)
Ending balance at Dec. 31, 2022 4,666 $ 4,088 418 (2) 162
Ending balance (in shares) at Dec. 31, 2022   40      
Total comprehensive income available to common shareholder 396   374 1 21
Dividend to parent (200)   (200)    
Ending balance at Dec. 31, 2023 4,862 $ 4,088 592 (1) 183
Ending balance (in shares) at Dec. 31, 2023   40      
Total comprehensive income available to common shareholder 352   329   23
Dividend to parent (232)   (232)    
Ending balance at Dec. 31, 2024 $ 4,982 $ 4,088 $ 689 $ (1) $ 206
Ending balance (in shares) at Dec. 31, 2024   40      
v3.25.0.1
Pay vs Performance Disclosure - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2024
Dec. 31, 2023
Dec. 31, 2022
Pay vs Performance Disclosure      
Net Income (Loss) $ 352 $ 395 $ 503
v3.25.0.1
Insider Trading Arrangements
 3 Months Ended
Dec. 31, 2024
Trading Arrangements, by Individual  
Rule 10b5-1 Arrangement Adopted false
Non-Rule 10b5-1 Arrangement Adopted false
Rule 10b5-1 Arrangement Terminated false
Non-Rule 10b5-1 Arrangement Terminated false
v3.25.0.1
Cybersecurity Risk Management, Strategy and Governance
 12 Months Ended
Dec. 31, 2024
Cybersecurity Risk Management, Strategy, and Governance [Line Items]  
Cybersecurity Risk Management Processes for Assessing, Identifying, and Managing Threats [Text Block]

Item 1C. Cybersecurity

 

Risk Management and Strategy

In an effort to reduce the likelihood and severity of cyber intrusions, Dominion Energy has a comprehensive cybersecurity program covering its operations, including DESC, designed to protect and preserve the confidentiality, integrity and availability of data and systems. Consideration of cybersecurity risks is a key component of Dominion Energy’s overall risk management and integrated into processes such as evaluation of potential new vendors or suppliers. Dominion Energy is subject to mandatory cybersecurity regulatory requirements, interface regularly with a wide range of external organizations and participate in classified briefings to maintain an awareness of current cybersecurity threats and vulnerabilities.

 

Dominion Energy’s corporate intelligence and security program includes both cybersecurity and threat intelligence components as part of its evaluation and mitigation of risks. The evaluation of risks includes consideration of cybersecurity and privacy risk, including potential impact on Dominion Energy’s employees, customers, supply chain and other stakeholders, intelligence briefings on notable cyber events impacting the industry and evaluation of insider threats. Dominion Energy utilizes a robust set of internal and third-party assessment tools to test its cyber risk management policies, practices and procedures as well as challenge assumptions upon which its defenses are built. These assessments provide opportunities for self-critical analysis and constructive feedback needed to build cyber resilience. Trainings are routinely provided to employees to help identify, avoid and mitigate cybersecurity threats and to ensure an understanding of Dominion Energy’s cyber risk management policies. In addition, risk assessments are conducted as a component of the evaluation of vendors and suppliers.

 

Dominion Energy’s current security posture and regulatory compliance efforts are intended to address the evolving and changing cyber threats. During the past three years, DESC has not experienced any cybersecurity incidents resulting in a material impact to their business strategy, results of operations or financial condition. DESC has identified the risk that a hostile cyber intrusion could severely impair DESC’s operations, lead to disclosure of confidential information, damage Dominion Energy’s reputation or otherwise have an adverse effect on DESC’s business as disclosed under the Operational Risks header within Item 1A. Risk Factors.

 

Governance

Dominion Energy’s Board of Directors, including its operations committee (effective in July 2024, previously its finance and risk oversight committee), provides oversight of risks from cybersecurity threats to all Dominion Energy operations, including DESC. Dominion Energy’s Board of Directors as well as its operations committee (effective in July 2024, previously its finance and risk oversight committee) receive presentations and reports throughout the year on cybersecurity and information security risk from management, including Dominion Energy’s chief security officer, director of cybersecurity (CISO) and chief information officer. These presentations and reports address a broad range of topics, including Dominion Energy’s cyber risk management program, updates on recent cybersecurity threats and incidents across the industry, policies and practices, industry trends, threat environment and vulnerability assessments and specific and ongoing efforts to prevent, detect and respond to internal and external critical threats, including management’s hosting in 2024 of its third practical exercise with external federal, state and local incident response partners. In addition, Dominion Energy’s Board of Directors receives briefings from time to time from outside experts for an independent view on cybersecurity risks, including assessments by independent consulting firms and legal counsel of the Company’s readiness and resilience.

 

Dominion Energy utilizes an organization structure known as a converged security model that brings together cybersecurity, physical security and threat intelligence within one department led by the chief security officer. The chief security officer joined Dominion Energy in this role in 2018 and has an extensive background in security having retired from the Federal Bureau of Investigation after a more than 20-year career focused on criminal, counter-terrorism, counter-intelligence and cyber investigations. The chief security officer belongs to the Federal Bureau of Investigation’s Domestic Security Alliance Council, the Department of Homeland Security’s Classified Intelligence Forum and is a member of the national Government/Business Executive Forum. In addition to serving on multiple university advisory boards, the chief security officer also serves on the Commonwealth of Virginia’s Informational Technology Advisory Council.

 

The director of cybersecurity (CISO) has over 30 years of experience at Dominion Energy primarily in various roles within the information technology department, including information technology risk management, as well as cybersecurity. The director of cybersecurity (CISO) has been involved in designing and evolving Dominion Energy’s cyber risk management policies, practices and procedures. This individual has deep relationships with key external partners and is recognized within the industry and the U.S. as a leading cybersecurity expert.

 

In addition, management of cybersecurity threats is shared with the chief information officer who is responsible for Dominion Energy’s technology assets including hardware, software, networks, servers and telecommunications. The chief information officer has over 25 years of experience at Dominion Energy primarily in various roles within the information technology department, including information technology risk management. In addition, the chief information officer previously served on the board of the Virginia Cybersecurity Partnership, a collaboration between private industry and the Federal Bureau of Investigation.

 

The chief security officer and chief information officer are supported by the senior vice president of administrative services as well as Dominion Energy’s operations, compliance, legal, audit, corporate risk, supply chain, human resources and accounting departments in executing its cybersecurity program. In addition, the chief security officer and chief information officer provide periodic updates concerning recent developments affecting cybersecurity and privacy risk to Dominion Energy’s executive cyber risk council, which includes executive officers responsible for administrative services, corporate affairs, supply chain, corporate secretary and corporate risk along with legal counsel.

 

Dominion Energy maintains a robust, tested and regularly revised Cyber Security Incident Response Plan and a Vendor Compromise Response Plan. These plans detail roles, responsibilities, and actions to be taken in response to a detected event whether internal or associated with a third-party service provider. The plans provide clear direction for escalation of information to leadership, including Dominion Energy’s Board of Directors as appropriate, and drive collaboration amongst relevant members of management representing cybersecurity, information technology, operations, supply chain, legal and accounting departments. As necessary, the COO, CFO and chief legal officer will advise the CEO on any incidents which could potentially have a material effect on Dominion Energy’s business operations, results of operations or financial condition.
Cybersecurity Risk Management Processes Integrated [Flag] true
Cybersecurity Risk Management Processes Integrated [Text Block] Consideration of cybersecurity risks is a key component of Dominion Energy’s overall risk management and integrated into processes such as evaluation of potential new vendors or suppliers. Dominion Energy is subject to mandatory cybersecurity regulatory requirements, interface regularly with a wide range of external organizations and participate in classified briefings to maintain an awareness of current cybersecurity threats and vulnerabilities.
Cybersecurity Risk Management Third Party Engaged [Flag] true
Cybersecurity Risk Third Party Oversight and Identification Processes [Flag] true
Cybersecurity Risk Materially Affected or Reasonably Likely to Materially Affect Registrant [Flag] false
Cybersecurity Risk Materially Affected or Reasonably Likely to Materially Affect Registrant [Text Block] During the past three years, DESC has not experienced any cybersecurity incidents resulting in a material impact to their business strategy, results of operations or financial condition. DESC has identified the risk that a hostile cyber intrusion could severely impair DESC’s operations, lead to disclosure of confidential information, damage Dominion Energy’s reputation or otherwise have an adverse effect on DESC’s business as disclosed under the Operational Risks header within Item 1A. Risk Factors.
Cybersecurity Risk Board of Directors Oversight [Text Block]

Dominion Energy’s Board of Directors, including its operations committee (effective in July 2024, previously its finance and risk oversight committee), provides oversight of risks from cybersecurity threats to all Dominion Energy operations, including DESC. Dominion Energy’s Board of Directors as well as its operations committee (effective in July 2024, previously its finance and risk oversight committee) receive presentations and reports throughout the year on cybersecurity and information security risk from management, including Dominion Energy’s chief security officer, director of cybersecurity (CISO) and chief information officer. These presentations and reports address a broad range of topics, including Dominion Energy’s cyber risk management program, updates on recent cybersecurity threats and incidents across the industry, policies and practices, industry trends, threat environment and vulnerability assessments and specific and ongoing efforts to prevent, detect and respond to internal and external critical threats, including management’s hosting in 2024 of its third practical exercise with external federal, state and local incident response partners. In addition, Dominion Energy’s Board of Directors receives briefings from time to time from outside experts for an independent view on cybersecurity risks, including assessments by independent consulting firms and legal counsel of the Company’s readiness and resilience.
Cybersecurity Risk Board Committee or Subcommittee Responsible for Oversight [Text Block] Dominion Energy’s Board of Directors, including its operations committee (effective in July 2024, previously its finance and risk oversight committee), provides oversight of risks from cybersecurity threats to all Dominion Energy operations, including DESC. Dominion Energy’s Board of Directors as well as its operations committee (effective in July 2024, previously its finance and risk oversight committee) receive presentations and reports throughout the year on cybersecurity and information security risk from management, including Dominion Energy’s chief security officer, director of cybersecurity (CISO) and chief information officer. These presentations and reports address a broad range of topics, including Dominion Energy’s cyber risk management program, updates on recent cybersecurity threats and incidents across the industry, policies and practices, industry trends, threat environment and vulnerability assessments and specific and ongoing efforts to prevent, detect and respond to internal and external critical threats, including management’s hosting in 2024 of its third practical exercise with external federal, state and local incident response partners.
Cybersecurity Risk Process for Informing Board Committee or Subcommittee Responsible for Oversight [Text Block] Dominion Energy’s Board of Directors receives briefings from time to time from outside experts for an independent view on cybersecurity risks, including assessments by independent consulting firms and legal counsel of the Company’s readiness and resilience.
Cybersecurity Risk Role of Management [Text Block]

The director of cybersecurity (CISO) has over 30 years of experience at Dominion Energy primarily in various roles within the information technology department, including information technology risk management, as well as cybersecurity. The director of cybersecurity (CISO) has been involved in designing and evolving Dominion Energy’s cyber risk management policies, practices and procedures. This individual has deep relationships with key external partners and is recognized within the industry and the U.S. as a leading cybersecurity expert.

 

In addition, management of cybersecurity threats is shared with the chief information officer who is responsible for Dominion Energy’s technology assets including hardware, software, networks, servers and telecommunications. The chief information officer has over 25 years of experience at Dominion Energy primarily in various roles within the information technology department, including information technology risk management. In addition, the chief information officer previously served on the board of the Virginia Cybersecurity Partnership, a collaboration between private industry and the Federal Bureau of Investigation.

 

The chief security officer and chief information officer are supported by the senior vice president of administrative services as well as Dominion Energy’s operations, compliance, legal, audit, corporate risk, supply chain, human resources and accounting departments in executing its cybersecurity program. In addition, the chief security officer and chief information officer provide periodic updates concerning recent developments affecting cybersecurity and privacy risk to Dominion Energy’s executive cyber risk council, which includes executive officers responsible for administrative services, corporate affairs, supply chain, corporate secretary and corporate risk along with legal counsel.

 

Dominion Energy maintains a robust, tested and regularly revised Cyber Security Incident Response Plan and a Vendor Compromise Response Plan. These plans detail roles, responsibilities, and actions to be taken in response to a detected event whether internal or associated with a third-party service provider. The plans provide clear direction for escalation of information to leadership, including Dominion Energy’s Board of Directors as appropriate, and drive collaboration amongst relevant members of management representing cybersecurity, information technology, operations, supply chain, legal and accounting departments. As necessary, the COO, CFO and chief legal officer will advise the CEO on any incidents which could potentially have a material effect on Dominion Energy’s business operations, results of operations or financial condition.
Cybersecurity Risk Management Positions or Committees Responsible [Flag] true
Cybersecurity Risk Management Positions or Committees Responsible [Text Block] The director of cybersecurity (CISO) has been involved in designing and evolving Dominion Energy’s cyber risk management policies, practices and procedures. This individual has deep relationships with key external partners and is recognized within the industry and the U.S. as a leading cybersecurity expert.management of cybersecurity threats is shared with the chief information officer who is responsible for Dominion Energy’s technology assets including hardware, software, networks, servers and telecommunications.
Cybersecurity Risk Management Expertise of Management Responsible [Text Block] The director of cybersecurity (CISO) has over 30 years of experience at Dominion Energy primarily in various roles within the information technology department, including information technology risk management, as well as cybersecurity. The chief information officer has over 25 years of experience at Dominion Energy primarily in various roles within the information technology department, including information technology risk management.
Cybersecurity Risk Process for Informing Management or Committees Responsible [Text Block]

The chief security officer and chief information officer are supported by the senior vice president of administrative services as well as Dominion Energy’s operations, compliance, legal, audit, corporate risk, supply chain, human resources and accounting departments in executing its cybersecurity program. In addition, the chief security officer and chief information officer provide periodic updates concerning recent developments affecting cybersecurity and privacy risk to Dominion Energy’s executive cyber risk council, which includes executive officers responsible for administrative services, corporate affairs, supply chain, corporate secretary and corporate risk along with legal counsel.

 

Dominion Energy maintains a robust, tested and regularly revised Cyber Security Incident Response Plan and a Vendor Compromise Response Plan. These plans detail roles, responsibilities, and actions to be taken in response to a detected event whether internal or associated with a third-party service provider. The plans provide clear direction for escalation of information to leadership, including Dominion Energy’s Board of Directors as appropriate,
Cybersecurity Risk Management Positions or Committees Responsible Report to Board [Flag] true
v3.25.0.1
Nature of Operations
 12 Months Ended
Dec. 31, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]  
Nature of Operations

1. NATURE OF OPERATIONS

DESC is a wholly-owned subsidiary of SCANA, which is a wholly-owned subsidiary of Dominion Energy.

DESC is engaged in the generation, transmission and distribution of electricity in the central, southern and southwestern portions of South Carolina. Additionally, DESC distributes natural gas to residential, commercial and industrial customers in South Carolina.

DESC manages its daily operations through one primary operating segment: Dominion Energy South Carolina. It also reports a Corporate and Other segment that primarily includes specific items attributable to its operating segment that are not included in profit measures evaluated by executive management in assessing the segment’s performance or in allocating resources.
v3.25.0.1
Summary of Significant Accounting Policies
 12 Months Ended
Dec. 31, 2024
Accounting Policies [Abstract]  
Summary of Significant Accounting Policies

2. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

General

DESC makes certain estimates and assumptions in preparing its Consolidated Financial Statements in accordance with GAAP. These estimates and assumptions affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the dates of the financial statements and the reported amounts of revenues, expenses and cash flows for the periods presented. Actual results may differ from those estimates.

DESC’s Consolidated Financial Statements include, after eliminating intercompany balances and transactions, the accounts of DESC, GENCO and Fuel Company. DESC has concluded that GENCO and Fuel Company are VIEs due to the members lacking the characteristics of a controlling financial interest. DESC is the primary beneficiary of GENCO and Fuel Company and therefore is required to consolidate the VIEs. The equity interests in GENCO and Fuel Company are held solely by SCANA, DESC’s parent. As a result, GENCO and Fuel Company’s equity and results of operations are reflected as noncontrolling interest in the Consolidated Financial Statements.

GENCO owns a coal-fired electric generating station with a 605 MW net generating capacity (summer rating). GENCO’s electricity is sold exclusively to DESC, pursuant to a FERC approved power purchase agreement and related operating agreement. The effects of these transactions are eliminated in consolidation. Fuel Company acquires, owns and provides financing for DESC’s nuclear fuel, certain fossil fuels and emission and other environmental allowances. See also Note 6.

Additionally, DESC purchases shared services from DES, an affiliated VIE that provides accounting, legal, finance and certain administrative and technical services to all Dominion Energy subsidiaries, including DESC. DESC has determined that it is not the primary beneficiary of DES as it does not have either the power to direct the activities that most significantly impact its economic performance or an obligation to absorb losses and benefits which could be significant to it. See Note 16 for amounts attributable to affiliates.

DESC reports certain contracts and instruments at fair value. See below and Note 9 for further information on fair value measurements.

DESC maintains pension and other postretirement benefit plans. See Note 11 for further information on these plans.

Certain amounts in the 2023 and 2022 Consolidated Financial Statements and Notes have been reclassified to conform to the 2024 presentation for comparative purposes; however, such reclassifications did not affect DESC’s net income, total assets, liabilities, equity or cash flows.

Utility Plant

Utility plant is stated at original cost. The costs of additions, replacements and betterments to utility plant, including direct labor, material and indirect charges for engineering, supervision and AFUDC, are added to utility plant accounts. The original cost of utility property retired or otherwise disposed of is removed from utility plant accounts and generally charged to accumulated depreciation. Cost of removal collections from utility customers are recorded as regulatory liabilities. The costs of repairs and replacements of items of property determined to be less than a unit of property or that do not increase the asset’s life or functionality are charged to expense.

AFUDC is a noncash item that reflects the period cost of capital devoted to plant under construction. This accounting practice results in the inclusion of, as a component of construction cost, the costs of debt and equity capital dedicated to construction investment. AFUDC is included in rate base investment and depreciated as a component of plant cost in establishing rates for utility services.

DESC calculated AFUDC using average composite rates of 5.3%, 5.3% and 2.7% for 2024, 2023 and 2022, respectively. These rates do not exceed the maximum rates allowed in the various regulatory jurisdictions. DESC capitalizes interest on nuclear fuel in process at the actual interest cost incurred.

For property subject to cost-of-service rate regulation that will be abandoned significantly before the end of its useful life, the net carrying value is reclassified from utility plant-in-service when it becomes probable it will be abandoned and recorded as a regulatory asset for amounts expected to be collected through future rates.

Provisions for depreciation and amortization are recorded using the straight-line method based on the estimated service lives of the various classes of property, and in most cases, include provisions for future cost of removal. The composite weighted-average depreciation rates for utility plant by function were as follows:

Year Ended December 31,

 

2024

 

 

2023

 

 

2022

 

(percent)

 

 

 

 

 

 

 

 

 

Generation

 

 

2.33

 

 

 

2.33

 

 

 

2.34

 

Transmission

 

 

2.53

 

 

 

2.54

 

 

 

2.36

 

Distribution

 

 

2.53

 

 

 

2.57

 

 

 

2.59

 

Storage

 

 

2.75

 

 

 

2.83

 

 

 

2.93

 

General and other

 

 

3.15

 

 

 

3.16

 

 

 

3.35

 

DESC records nuclear fuel amortization using the units-of-production method, which is included in fuel used in electric generation and recovered through the fuel cost component of retail electric rates.

Major Maintenance

Planned major maintenance costs related to certain fossil fuel turbine generator equipment, nuclear refueling outages and cyclical tree trimming and vegetation management are collected in rates and accrued in periods other than when incurred in accordance with approval by the South Carolina Commission for such accounting treatment and rate recovery of expenses accrued thereunder. The difference between such cumulative major maintenance costs and cumulative collections is classified as a regulatory asset or regulatory liability on the consolidated balance sheet. Other planned major maintenance is expensed when incurred.

DESC is authorized to collect $25 million annually through electric rates to offset certain turbine generator maintenance expenditures. For the years ended December 31, 2024, 2023 and 2022, DESC incurred $16 million, $20 million and $20 million, respectively, for turbine generator maintenance.

Nuclear refueling outages are scheduled 18 months apart. As approved by the South Carolina Commission, DESC accrued $17 million annually through August 2024 and $24 million annually beginning September 2024 for its portion of the nuclear refueling outages, that are scheduled to occur from the fall of 2024 through the fall of 2030 as well as unrecovered balances from the previous accrual cycle. Refueling outage costs incurred for which DESC was responsible totaled $42 million in 2024, $26 million in 2023 and $1 million in 2022.

Effective September 2021, DESC implemented a tree trimming and vegetation management accrual where costs associated with cyclical tree trimming and vegetation management are accrued over the five-year operating cycle DESC seeks to maintain for such activities. As approved by the South Carolina Commission, DESC accrued $28 million annually through August 2024 and $34 million annually beginning September 2024. During the years ended December 31, 2024, 2023 and 2022, DESC incurred costs totaling $29 million, $31 million and $33 million, respectively.

Asset Retirement Obligations

DESC recognizes AROs at fair value as incurred or when sufficient information becomes available to determine a reasonable estimate of the fair value of future retirement activities to be performed, for which a legal obligation exists. These amounts are generally capitalized as costs of the related tangible long-lived assets. Since relevant market information is not available, fair value is estimated using discounted cash flow analyses. Periodically, DESC assesses its AROs to determine if circumstances indicate that estimates of the amounts or timing of future cash flows associated with retirement activities have changed. AROs are adjusted when significant changes in the amounts or timing of future cash flows are identified. DESC reports accretion of AROs and depreciation on asset retirement costs as an adjustment to regulatory assets.

Nuclear Decommissioning

Based on a decommissioning cost study completed in 2020, DESC’s two-thirds share of estimated site-specific nuclear decommissioning costs for Summer, including the cost of decommissioning plant components both subject to and not subject to radioactive contamination, totals $831 million, stated in 2024 dollars. Santee Cooper is responsible for decommissioning costs related to its one-third ownership interest in Summer. The cost estimate assumes that the site will be maintained over a period of approximately 60 years in such a manner as to allow for subsequent decontamination that would permit release for unrestricted use.

Under DESC’s method of funding decommissioning costs, DESC transfers to an external trust fund the amounts collected through rates ($3 million in each period presented), less expenses. The trust invests the amounts transferred into insurance policies on the lives of certain company personnel. Insurance proceeds are reinvested in insurance policies. The asset balance held in trust reflects the net cash surrender value of the insurance policies and cash held by the trust. Management intends for the fund, including earnings thereon, to provide for all eventual decommissioning expenditures for Summer on an after-tax basis.

Cash, Restricted Cash and Equivalents

Cash, restricted cash and equivalents include cash on hand, cash in banks and temporary investments purchased with an original maturity of three months or less.

 

Restricted Cash and Equivalents

DESC may hold restricted cash and equivalent balances that consists of federal assistance funds to be used towards customer bill assistance.

 

The following table provides a reconciliation of the total cash, restricted cash and equivalents reported within DESC’s Consolidated Balance Sheets to the corresponding amounts reported within DESC’s Consolidated Statements of Cash Flows for the years ended December 31, 2024, 2023 and 2022:

 

 

 

Cash, Restricted Cash and Equivalents at End/Beginning of Year

 

 

 

December 31, 2024

 

 

December 31, 2023

 

 

December 31, 2022

 

 

December 31, 2021

 

(millions)

 

 

 

 

 

 

 

 

 

 

 

 

Cash and cash equivalents

 

$

—

 

 

$

1

 

 

$

11

 

 

$

30

 

Restricted cash and equivalents(1)

 

 

—

 

 

 

—

 

 

 

—

 

 

 

24

 

Cash, restricted cash and equivalents shown in the
   Consolidated Statements of Cash Flows

 

$

—

 

 

$

1

 

 

$

11

 

 

$

54

 
(1)
Restricted cash and equivalent balances are presented within other current assets on the Consolidated Balance Sheets.

Receivables

Customer receivables reflect amounts due from customers arising from the delivery of energy or related services and include both billed and unbilled amounts earned pursuant to revenue recognition practices described in Note 4. Customer receivables are generally due within one month of receipt of invoices which are presented on a monthly cycle basis. Unbilled revenues totaled $176 million at both December 31, 2024 and 2023.

DESC sells electricity and natural gas and provides distribution and transmission services to customers in South Carolina. Management believes that this geographic concentration risk is mitigated by the diversity of DESC’s customer base, which includes a large number of residential, commercial and industrial customers. Credit risk associated with accounts receivable is limited due to the large number of customers. DESC’s exposure to potential concentrations of credit risk results primarily from amounts due from Santee Cooper related to the jointly owned nuclear generating facility at Summer. Such receivables represented approximately 7% of DESC’s accounts receivable balance at December 31, 2024.

Inventories

Materials and supplies include the average cost of transmission, distribution and generating plant materials. Materials are charged to inventory when purchased and then expensed or capitalized to plant, as appropriate, at weighted-average cost when used. Fuel inventory includes the average cost of coal, natural gas, fuel oil and emission allowances. Fuel is charged to inventory when purchased and is expensed, at weighted-average cost, as used and recovered through fuel cost recovery rates approved by the South Carolina Commission.

Income Taxes

A consolidated federal income tax return is filed for Dominion Energy and its subsidiaries, including DESC. In addition, where applicable, combined income tax returns for Dominion Energy, including DESC, are filed in various states including South Carolina; otherwise, separate state income tax returns are filed.

DESC participates in an intercompany tax sharing agreement with Dominion Energy. Current income taxes are based on taxable income or loss and credits determined on a separate company basis.

Under the agreements, if a subsidiary incurs a tax loss or earns a credit, recognition of current income tax benefits is limited to refunds of prior year taxes obtained by the carryback of the net operating loss or credit or to the extent the tax loss or credit is absorbed by the taxable income of other Dominion Energy consolidated group members. Otherwise, the net operating loss or credit is carried forward and is recognized as a deferred tax asset until realized.

Accounting for income taxes involves an asset and liability approach. Deferred income tax assets and liabilities are provided, representing future effects on income taxes for temporary differences between the bases of assets and liabilities for financial reporting and tax purposes. Accordingly, deferred taxes are recognized for the future consequences of different treatments used for the reporting of transactions in financial accounting and income tax returns. DESC establishes a valuation allowance when it is more-likely-than-not that all, or a portion, of a deferred tax asset will not be realized. DESC did not have any valuation allowances recorded for the periods presented. Where the treatment of temporary differences is different for rate-regulated operations, a regulatory asset is recognized if it is probable that future revenues will be provided for the payment of deferred tax liabilities.

DESC recognizes positions taken, or expected to be taken, in income tax returns that are more-likely-than-not to be realized, assuming that the position will be examined by tax authorities with full knowledge of all relevant information. At December 31, 2024 and 2023, DESC had $38 million and $62 million, respectively, of unrecognized tax benefits.

If it is not more-likely-than-not that a tax position, or some portion thereof, will be sustained, the related tax benefits are not recognized in the financial statements. Unrecognized tax benefits may result in an increase in income taxes payable, a reduction of income tax refunds receivable or changes in deferred taxes. Also, when uncertainty about the deductibility of an amount is limited to the timing of such deductibility, the increase in income taxes payable (or reduction in tax refunds receivable) is accompanied by a decrease in deferred tax liabilities. Except when such amounts are presented net with amounts receivable from or amounts prepaid to tax authorities, noncurrent income taxes payable related to unrecognized tax benefits are classified in other deferred credits and other liabilities on the Consolidated Balance Sheets and current payables are included in taxes accrued on the Consolidated Balance Sheets.

DESC recognizes interest on underpayments and overpayments of income taxes in interest expense and interest income, respectively. Penalties are also recognized in other expenses. DESC recorded interest expense of $12 million in 2024 with inconsequential amounts recorded in 2023 and 2022.

At December 31, 2024, DESC had an income tax-related affiliated payable of $12 million to Dominion Energy. This balance is expected to be paid to Dominion Energy in 2025.

At December 31, 2023, DESC had an income tax-related affiliated payable of $15 million to Dominion Energy. This balance was paid to Dominion Energy in 2024.

At DESC investment tax credits are deferred and amortized over the service lives of the properties giving rise to the credits. Production tax credits are recognized as energy is generated and sold.

Regulatory Assets and Liabilities

The accounting for DESC’s regulated electric and gas operations differs from the accounting for nonregulated operations in that DESC is required to reflect the effect of rate regulation in its Consolidated Financial Statements. For regulated businesses subject to federal or state cost-of-service rate regulation, regulatory practices that assign costs to accounting periods may differ from accounting methods generally applied by nonregulated companies. When it is probable that regulators will permit the recovery of current costs through future rates charged to customers, these costs that otherwise would be expensed by nonregulated companies are deferred as regulatory assets. Likewise, regulatory liabilities are recognized when it is probable that regulators will require customer refunds or other benefits through future rates or when revenue is collected from customers for expenditures that have yet to be incurred.

 

DESC evaluates whether or not recovery of its regulatory assets through future rates is probable as well as whether a regulatory liability due to customers is probable and makes various assumptions in its analyses. These analyses are generally based on:

 

•
Orders issued by regulatory commissions, legislation and judicial actions;
•
Past experience; and
•
Discussions with applicable regulatory authorities and legal counsel.

Generally, regulatory assets and liabilities are amortized into income over the period authorized by the regulator. If recovery of a regulatory asset is determined to be less than probable, it will be written off in the period such assessment is made. A regulatory liability, if considered probable, will be recorded in the period such assessment is made or reversed into earnings if no longer probable. See Note 3 to the Consolidated Financial Statements for additional information.

Derivative Instruments

DESC is exposed to the impact of market fluctuations in the price of electricity and natural gas it markets and purchases, as well as interest rate risk in its business operations. DESC uses derivative instruments such as physical forwards, options and swaps to manage commodity and/or interest rate risks of its business operations.

 

Derivative assets and liabilities are presented gross on DESC’s Consolidated Balance Sheets. Derivative contracts representing unrealized gain positions and purchased options are reported as derivative assets. Derivative contracts representing unrealized losses and options sold are reported as derivative liabilities. All derivatives, except those for which an exception applies, are required to be reported in the Consolidated Balance Sheets at fair value. One of the exceptions to fair value accounting, normal purchases and normal sales, may be elected when the contract satisfies certain criteria, including a requirement that physical delivery of the underlying commodity is probable. Contracts for the future purchase of certain quantities of natural gas that no longer meet the criteria for the normal purchase normal sale exception are accounted for as derivative contracts. Expenses and revenues resulting from deliveries under normal purchase contracts and normal sales contracts, respectively, are included in earnings at the time of contract performance. See Fair Value Measurements below for additional information about fair value measurements and associated valuation methods for derivatives.

 

DESC’s derivative contracts include over-the-counter transactions. Over-the-counter contracts are bilateral contracts that are transacted directly with a third party. Certain over-the-counter contracts contain contractual rights of setoff through master netting arrangements and contract default provisions. In addition, the contracts are subject to conditional rights of setoff through counterparty nonperformance, insolvency, or other conditions.

 

In general, most over-the-counter transactions are subject to collateral requirements. Types of collateral for over-the-counter contracts include cash, letters of credit and, in some cases, other forms of security, none of which are subject to restrictions.

 

DESC does not offset amounts recognized for the right to reclaim cash collateral or the obligation to return cash collateral against amounts recognized for derivative instruments executed with the same counterparty under the same master netting arrangement. DESC had no margin assets or liabilities associated with cash collateral at December 31, 2024 and 2023. See Note 8 for further information about derivatives.

 

To manage price and interest rate risk, DESC holds derivative instruments that are not designated as hedges for accounting purposes. However, to the extent DESC does not hold offsetting positions for such derivatives, it believes these instruments represent economic hedges that mitigate its exposure to fluctuations in commodity prices or interest rates. All income statement activity, including amounts realized upon settlement, is presented in operating expenses and interest charges based on the nature of the underlying risk. For derivative instruments that are not accounted for as cash flow hedges, the cash flows from the derivatives are classified in operating cash flows.

 

Changes in the fair value of derivative instruments result in the recognition of regulatory assets or regulatory liabilities. Realized gains or losses on the derivative instruments are generally recognized when the related transactions impact earnings.

Derivative Instruments Designated as Hedging Instruments

In accordance with accounting guidance pertaining to derivatives and hedge accounting, DESC designated a portion of its derivative instruments as cash flow hedges for accounting purposes. For derivative instruments that are accounted for as cash flow hedges, the cash flows from the derivatives and from the related hedged items are classified in operating cash flows.

Cash Flow Hedges- DESC used interest rate swaps to hedge its exposure to variable interest rates on long-term debt. For transactions in which DESC is hedging the variability of cash flows, changes in the fair value of the derivatives are reported in regulatory assets or liabilities. Any derivative gains or losses reported in regulatory assets or liabilities are reclassified to earnings when the forecasted item is included in earnings, or earlier, if it becomes probable that the forecasted transaction will not occur. For cash flow hedge transactions, hedge accounting is discontinued if the occurrence of the forecasted transaction is no longer probable. At December 31, 2024, all derivatives previously designated as cash flow hedges have settled and are being amortized over the life of the debt.

Pursuant to regulatory orders, interest rate derivatives entered into by DESC after October 2013 were not designated for accounting purposes as cash flow hedges, and fair value changes and settlement amounts related to them have been recorded as regulatory assets and liabilities. Settlement losses on swaps generally have been amortized over the lives of subsequent debt issuances, and gains have been amortized to interest charges or have been applied as otherwise directed by the South Carolina Commission.

Fair Value Measurements

Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability (exit price) in an orderly transaction between market participants at the measurement date. However, the use of a mid-market pricing convention (the mid-point between bid and ask prices) is permitted. Fair values are based on assumptions that market participants would use when pricing an asset or liability, including assumptions about risk and the risks inherent in valuation techniques and the inputs to valuations. This includes not only the credit standing of counterparties involved and the impact of credit enhancements but also the impact of DESC’s own nonperformance risk on its liabilities. Fair value measurements assume that the transaction occurs in the principal market for the asset or liability (the market with the most volume and activity for the asset or liability from the perspective of the reporting entity), or in the absence of a principal market, the most advantageous market for the asset or liability (the market in which the reporting entity would be able to maximize the amount received or minimize the amount paid). DESC applies fair value measurements to certain assets and liabilities including commodity and interest rate derivative instruments. DESC applies credit adjustments to its derivative fair values in accordance with the requirements described above.

Inputs and Assumptions

Fair value is based on actively-quoted market prices, if available. In the absence of actively-quoted market prices, price information is sought from external sources, including industry publications, and to a lesser extent, broker quotes. When evaluating pricing information provided by Designated Contract Market settlement pricing, other pricing services, or brokers, DESC considers the ability to transact at the quoted price, i.e. if the quotes are based on an active market or an inactive market and to the extent which pricing models are used, if pricing is not readily available. If pricing information from external sources is not available, or if DESC believes that observable pricing is not indicative of fair value, judgment is required to develop the estimates of fair value. In those cases the unobservable inputs are developed and substantiated using historical information, available market data, third-party data and statistical analysis. Periodically, inputs to valuation models are reviewed and revised as needed, based on historical information, updated market data, market liquidity and relationships and changes in third-party sources.

For options and contracts with option-like characteristics where observable pricing information is not available from external sources, DESC generally uses a model that considers time value, the volatility of the underlying commodities and other relevant assumptions when estimating fair value. For contracts with unique characteristics, DESC may estimate fair value using a discounted cash flow approach deemed appropriate in the circumstances and applied consistently from period to period. For individual contracts, the use of different valuation models or assumptions could have a significant effect on the contract’s estimated fair value.

The inputs and assumptions used in measuring fair value include the following:

 

 

Derivative Contracts

Inputs and assumptions

 

Commodity

 

Interest Rate

Forward commodity prices

 

X

 

 

Transaction prices

 

X

 

 

Price volatility

 

X

 

 

Price correlation

 

X

 

 

Volumes

 

X

 

 

Commodity location

 

X

 

 

Interest rates

 

X

 

 

Interest rate curves

 

 

 

X

Credit quality of counterparties and DESC

 

X

 

X

Credit enhancements

 

X

 

X

Time value

 

X

 

X

Notional value

 

 

 

X

 

In addition, investments are measured at fair value utilizing quoted securities prices and indices.

Levels

DESC utilizes the following fair value hierarchy, which prioritizes the inputs to valuation techniques used to measure fair value into three broad levels:

•
Level 1-Quoted prices (unadjusted) in active markets for identical assets and liabilities that it has the ability to access at the measurement date. Instruments categorized in Level 1 primarily consist of cash equivalents and other.
•
Level 2-Inputs other than quoted prices included within Level 1 that are either directly or indirectly observable for the asset or liability, including quoted prices for similar assets or liabilities in active markets, quoted prices for identical or similar assets or liabilities in inactive markets, inputs other than quoted prices that are observable for the asset or liability, and inputs that are derived from observable market data by correlation or other means. Instruments categorized in Level 2 include commodity forwards and interest rate swaps.
•
Level 3-Unobservable inputs for the asset or liability, including situations where there is little, if any, market activity for the asset or liability. Instruments categorized in Level 3 for DESC consist of long-dated commodity derivatives and certain natural gas options.

The fair value hierarchy gives the highest priority to quoted prices in active markets (Level 1) and the lowest priority to unobservable data (Level 3). In some cases, the inputs used to measure fair value might fall in different levels of the fair value hierarchy. In these cases, the lowest level input that is significant to a fair value measurement in its entirety determines the applicable level in the fair value hierarchy. Assessing the significance of a particular input to the fair value measurement in its entirety requires judgment, considering factors specific to the asset or liability.

Debt Issuance Costs

DESC defers and amortizes debt issuance costs and debt premiums or discounts over the expected lives of the respective debt issues, considering maturity dates and, if applicable, redemption rights held by others. Deferred debt issuance costs are recorded as a reduction in long-term debt in the Consolidated Balance Sheets. Amortization of the issuance costs is reported as interest charges. As permitted by regulatory authorities, gains or losses resulting from the refinancing or redemption of debt that are probable of recovery through future rates are deferred and amortized.

Environmental

An environmental assessment program is maintained to identify and evaluate current and former operations sites that could require environmental clean-up. As site assessments are initiated, estimates are made of the amount of expenditures, if any, deemed necessary to investigate and remediate each site. Environmental remediation liabilities are accrued when the criteria for loss contingencies are met. These estimates are refined as additional information becomes available; therefore, actual expenditures could differ significantly from the original estimates. Probable and estimable costs are accrued related to environmental sites on an undiscounted basis. Amounts estimated and accrued to date for site assessments and clean-up relate solely to regulated operations. Amounts expected to be recovered through rates are recorded in regulatory assets and, if applicable, amortized over approved amortization periods. Other environmental costs are expensed as incurred.

Statement of Operations Presentation

Revenues and expenses arising from regulated businesses are presented within operating income, and all other activities are presented within other income (expense), net.

Operating Revenue

Operating revenue is recorded on the basis of services rendered, commodities delivered or contracts settled and includes amounts yet to be billed to customers. DESC collects sales, consumption, consumer utility taxes and sales taxes; however, these amounts are excluded from revenue and are recorded as liabilities until they are remitted to the respective taxing authority.

The primary types of sales and service activities reported as operating revenue for DESC are as follows:

Revenue from Contracts with Customers

•
Regulated electric sales consist primarily of state-regulated retail electric sales, and federally-regulated wholesale electric sales and electric transmission services;
•
Regulated gas sales consist primarily of state-regulated natural gas sales and related distribution services; and
•
Other regulated revenue consists primarily of miscellaneous service revenue from electric and gas distribution operations and sales of excess electric capacity and other commodities.

Other Revenue

•
Other revenue consists primarily of alternative revenue programs, gains and losses from derivative instruments not subject to hedge accounting and lease revenues.

DESC records refunds to customers as required by the South Carolina Commission as a reduction to regulated electric sales or regulated gas sales, as applicable. Revenues from electric and gas sales are recognized over time, as the customers of DESC consume gas and electricity as it is delivered. Sales of products and services typically transfer control and are recognized as revenue upon delivery of the product or service. The customer is able to direct the use of, and obtain substantially all of the benefits from, the product at the time the product is delivered. The contract with the customer states the final terms of the sale, including the description, quantity and price of each product or service purchased. Payment for most sales and services varies by contract type, but is typically due within a month of billing.

 

DESC customers subject to an electric fuel cost recovery component or a PGA are billed based on a fuel or cost of gas factor calculated in accordance with cost recovery procedures approved by the South Carolina Commission and subject to adjustment periodically. Any difference between actual costs and amounts contained in rates is adjusted through revenue and is deferred and included when making the next adjustment to the cost recovery factors.

 

Certain amounts deferred for the WNA arise under specific arrangements with regulators rather than customers and are accounted for as an alternative revenue program. This alternative revenue is included within Other operating revenues, separate from revenue arising from contracts with customers, in the month such adjustments are deferred within regulatory accounts. As permitted, DESC has elected to reduce the regulatory accounts in the period when such amounts are reflected on customer bills without affecting operating revenues.

 

Performance obligations which have not been satisfied by DESC relate primarily to demand or standby service for natural gas. Demand or standby charges for natural gas arise when an industrial customer reserves capacity on assets controlled by the service provider and may use that capacity to move natural gas it has acquired from other suppliers. For all periods presented, the amount of revenue recognized by DESC for these charges is equal to the amount of consideration DESC has a right to invoice and corresponds directly to the value transferred to the customer.

Leases

DESC leases certain assets including vehicles, real estate, office equipment and other assets under both operating and finance leases. For operating leases, rent expense is recognized on a straight-line basis over the term of the lease agreement, subject to regulatory framework. Rent expense associated with operating leases, short-term leases and variable leases is primarily recorded in other operations and maintenance expense in the Consolidated Statements of Comprehensive Income. Amortization expense and interest charges associated with finance leases are deferred within regulatory assets in the Consolidated Balance Sheets and amortized into the Consolidated Statements of Comprehensive Income.

Certain leases include one or more options to renew, with renewal terms that can extend the lease from one to 70 years. The exercise of renewal options is solely at DESC’s discretion and is included in the lease term if the option is reasonably certain to be exercised. A right-of-use asset and corresponding lease liability for leases with original lease terms of one year or less are not included in the Consolidated Balance Sheets, unless such leases contain renewal options that DESC is reasonably certain will be exercised.

The determination of the discount rate utilized has a significant impact on the calculation of the present value of the lease liability included in the Consolidated Balance Sheets. For DESC’s leased assets, the discount rate implicit in the lease is generally unable to be determined from a lessee perspective. As such, DESC uses internally-developed incremental borrowing rates as a discount rate in the calculation of the present value of the lease liability. The incremental borrowing rates are determined based on an analysis of DESC’s publicly available secured borrowing rates over various lengths of time that most closely correspond to DESC’s lease maturities.

New Accounting Standards

Segment Disclosures

In November 2023, the FASB issued revised accounting guidance for reportable segments. The revised guidance requires disclosure of significant segment expenses and other segment items on an annual and interim basis and to provide in interim periods all disclosures about a reportable segment’s profit or loss and assets that are currently required annually. Additionally, it requires disclosure of the title and position of the CODM. The revised guidance does not change how an entity identifies its operating

segments, aggregates them or applies the quantitative thresholds to determine its reportable segments. The new standard is effective for fiscal years beginning after December 15, 2023, and interim periods within fiscal years beginning after December 15, 2024, with early adoption permitted and requires retrospective application to all prior periods presented. This revised guidance only impacted DESC’s disclosures with no impacts to its results of operations, cash flows or financial condition.

Income Tax Disclosures

In December 2023, the FASB issued revised accounting guidance for income taxes. The revised guidance requires disclosure of disaggregated information about an entity’s effective tax rate reconciliation as well as additional information on income taxes paid. The new standard is effective for fiscal years beginning after December 15, 2024, with early adoption permitted and allows either prospective or retrospective application. DESC expects this revised guidance to only impact its disclosures with no impacts to its results of operations, cash flows or financial condition.

Climate-Related Disclosures

In March 2024, the SEC issued guidance for climate-related disclosures. The guidance requires disclosure of the financial statement impacts of severe weather events and other natural conditions, including amounts capitalized or expensed as well as any associated recoveries. In addition, the guidance requires disclosure of amounts related to renewable energy credits or carbon offsets if utilized as a material component of plans to achieve climate-related targets or goals. This guidance is currently subject to a stay issued by the SEC. Should this guidance become effective, DESC expects it to only impact its disclosures with no impacts to its results of operations, cash flows or financial condition.

Expense Disaggregation Disclosures

In November 2024, the FASB issued revised accounting guidance for income statement expense disaggregation disclosures. The revised guidance requires disclosure of disaggregated information about specific expense categories in commonly presented income statement expense captions. The new standard is effective for fiscal years beginning after December 15, 2026, and interim periods within fiscal years beginning after December 15, 2027, with early adoption permitted and allows either prospective or retrospective application. DESC expects this revised guidance to only impact its disclosures with no impacts to its results of operations, cash flows or financial condition.
v3.25.0.1
Rate and Other Regulatory Matters
 12 Months Ended
Dec. 31, 2024
Regulated Operations [Abstract]  
Rate and Other Regulatory Matters

3. RATE AND OTHER REGULATORY MATTERS

Regulatory Matters Involving Potential Loss Contingencies

As a result of issues generated in the ordinary course of business, DESC is involved in various regulatory matters. Certain regulatory matters may ultimately result in a loss; however, as such matters are in an initial procedural phase, involve uncertainty as to the outcome of pending reviews or orders and/or involve significant factual issues that need to be resolved, it is not possible for DESC to estimate a range of possible loss. For regulatory matters that DESC cannot estimate, a statement to this effect is made in the description of the matter. Other matters may have progressed sufficiently through the regulatory process such that DESC is able to estimate a range of possible loss. For regulatory matters that DESC is able to reasonably estimate a range of possible losses, an estimated range of possible loss is provided, in excess of the accrued liability (if any) for such matters. Any estimated range is based on currently available information, involves elements of judgment and significant uncertainties and may not represent DESC’s maximum possible loss exposure. The circumstances of such regulatory matters will change from time to time and actual results may vary significantly from the current estimate. For current matters not specifically reported below, management does not anticipate that the outcome from such matters would have a material effect on DESC’s financial position, liquidity or results of operations.

Other Regulatory Matters

Electric Base Rate Case

In March 2024, DESC filed its retail electric base rate case and schedules with the South Carolina Commission. DESC proposed a non-fuel, base rate increase of $295 million, partially offset by a net decrease in storm damage and DSM components of $4 million. If approved, the overall proposed rate increase of $291 million, or 12.59%, would be effective on and after the first billing cycle of September 2024. The base rate increase was proposed to recover the significant investment in assets and operating resources required to serve an expanding customer base, maintain the safety, reliability and efficiency of DESC’s system and meet increasingly stringent reliability, security and environmental requirements for the benefit of South Carolina customers. DESC presented an earned ROE of 4.32% based upon a fully-adjusted test period. The proposed rates would provide for an earned ROE of 10.60% compared to the currently authorized ROE of 9.50%.

In July 2024, DESC, the ORS and other parties of record filed a comprehensive settlement agreement with the South Carolina Commission for approval. The comprehensive settlement agreement provides for a non-fuel, base rate increase of $219 million prior to the effect of South Carolina Commission-ordered DSM reductions commencing with service rendered on September 1, 2024 and an authorized ROE of 9.94%. In addition, the comprehensive settlement agreement includes that DESC would provide a one-time bill

credit in 2024 of approximately $7 million primarily to residential customers. In August 2024, the South Carolina Commission voted to approve the settlement agreement.

In connection with this matter, in the third quarter of 2024 DESC recorded a charge of $58 million ($44 million after tax) (reflected within the Corporate and Other segment), composed of $55 million within impairment of assets and other charges, including $50 million to write down certain materials and supplies inventory, and $3 million within other income (expense), net.

Electric – Cost of Fuel

DESC’s retail electric rates include a cost of fuel component approved by the South Carolina Commission which may be adjusted periodically to reflect changes in the price of fuel purchased by DESC.

In February 2024, DESC filed with the South Carolina Commission a proposal to decrease the total fuel cost component of retail electric rates. DESC’s proposed adjustment is designed to recover DESC’s current base fuel costs, including its existing under-collected balance, over the 12-month period beginning with the first billing cycle of May 2024. In addition, DESC proposed an increase to its variable environmental and avoided capacity cost component. The net effect is a proposed annual decrease of $315 million. In March 2024, DESC, the ORS and another party of record filed a settlement agreement with the South Carolina Commission for approval to make certain adjustments to the February 2024 filing that would result in a net annual decrease of $316 million. In April 2024, the South Carolina Commission voted to approve the settlement agreement, with rates effective May 2024.

In February 2025, DESC filed with the South Carolina Commission a proposal to increase the total fuel cost component of retail electric rates. DESC’s proposed adjustment is designed to recover DESC’s current base fuel costs, including its existing under-collected balance, over the 12-month period beginning with the first billing cycle of May 2025. In addition, DESC proposed an increase to its variable environmental and avoided capacity cost component. The net effect is a proposed annual increase of $154 million. This matter is pending.

Electric Transmission Projects

In March 2024, DESC filed an application with the South Carolina Commission requesting approval of a CPCN to construct and operate the Church Creek-Charleston Transmission Line, comprised of a 7-mile 230 kV transmission line and associated facilities in Charleston County, South Carolina with an estimated total project cost of $40 million. In July 2024, the South Carolina Commission approved the application.

In December 2024, DESC filed an application with the South Carolina Commission requesting approval of a CPCN to construct and operate the Ritter-Yemassee Transmission Line #2, comprised of a 17-mile 230 kV transmission line and associated facilities in Colleton and Hampton Counties, South Carolina with an estimated total project cost of $55 million. This matter is pending.

Electric – Other

DESC has approval for a DSM rider through which it recovers expenditures related to its DSM programs. In January 2024, DESC filed an application with the South Carolina Commission seeking approval to recover $47 million of costs and net lost revenues associated with these programs, along with an incentive to invest in such programs. DESC requested that rates be effective with the first billing cycle of May 2024. In April 2024, the South Carolina Commission approved the request, effective with the first billing cycle of May 2024. In January 2025, DESC filed an application with the South Carolina Commission seeking approval to recover $46 million of costs and net lost revenues associated with these programs, along with an incentive to invest in such programs. DESC requested that rates be effective with the first billing cycle of May 2025. This matter is pending.

DESC utilizes a pension costs rider approved by the South Carolina Commission which is designed to allow recovery of projected pension costs, including under-collected balances or net of over-collected balances, as applicable. The rider is typically reviewed for adjustment every 12 months with any resulting increase or decrease going into effect beginning with the first billing cycle in May. In February 2024, DESC requested that the South Carolina Commission approve an adjustment to this rider to increase annual revenue by $9 million. In April 2024, the South Carolina Commission approved the request. In February 2025, DESC requested that the South Carolina Commission approve an adjustment to this rider to decrease annual revenue by $13 million. This matter is pending.

Natural Gas Rates

DESC’s natural gas tariffs include a PGA that provides for the recovery of actual gas costs incurred, including transportation costs. DESC’s gas rates are calculated using a methodology which may adjust the cost of gas monthly based on a 12-month rolling average, and its gas purchasing policies and practices are reviewed annually by the South Carolina Commission.

In June 2024, DESC filed with the South Carolina Commission its monitoring report for the 12-month period ended March 31, 2024 with a total revenue requirement of $523 million. This represents a $13 million base rate increase, after certain adjustments, under the terms of the Natural Gas Rate Stabilization Act effective with the first billing cycle of November 2024. In October 2024, the South Carolina Commission approved a $13 million base rate increase after certain adjustments, effective with the first billing cycle of November 2024.

Regulatory Assets and Regulatory Liabilities

Rate-regulated utilities recognize in their financial statements certain revenues and expenses in different periods than do other enterprises. As a result, DESC has recorded regulatory assets and regulatory liabilities which are summarized in the following table. Except for NND Project costs and certain other unrecovered costs referenced herein, substantially all regulatory assets are either explicitly excluded from rate base or are effectively excluded from rate base due to their being offset by related liabilities.

 

At December 31,

 

2024

 

 

2023

 

(millions)

 

 

 

 

 

 

Regulatory assets:

 

 

 

 

 

 

NND Project costs(1)

 

$

138

 

 

$

138

 

AROs(2)

 

 

8

 

 

 

44

 

Deferred employee benefit plan costs(3)

 

 

8

 

 

 

11

 

Other unrecovered plant(4)

 

 

18

 

 

 

19

 

DSM programs(5)

 

 

24

 

 

 

22

 

Cost of fuel and purchased gas under-collections(6)

 

 

35

 

 

 

154

 

Other

 

 

68

 

 

 

56

 

Regulatory assets - current

 

 

299

 

 

 

444

 

NND Project costs(1)

 

 

1,811

 

 

 

1,949

 

AROs(2)

 

 

695

 

 

 

379

 

Deferred employee benefit plan costs(3)

 

 

94

 

 

 

118

 

Interest rate hedges(7)

 

 

167

 

 

 

168

 

Other unrecovered plant(4)

 

 

89

 

 

 

66

 

DSM programs(5)

 

 

49

 

 

 

46

 

Environmental remediation costs(8)

 

 

42

 

 

 

34

 

Deferred storm damage costs(9)

 

 

76

 

 

 

40

 

Deferred transmission operating costs(10)

 

 

72

 

 

 

74

 

Derivatives(11)

 

 

95

 

 

 

103

 

Other(12)

 

 

152

 

 

 

130

 

Regulatory assets - noncurrent

 

 

3,342

 

 

 

3,107

 

Total regulatory assets

 

$

3,641

 

 

$

3,551

 

Regulatory liabilities:

 

 

 

 

 

 

Monetization of guaranty settlement(13)

 

$

67

 

 

$

67

 

Income taxes refundable through future rates(14)

 

 

24

 

 

 

37

 

Reserve for refunds to electric utility customers(15)

 

 

73

 

 

 

83

 

Derivatives(11)

 

 

27

 

 

 

12

 

Other

 

 

10

 

 

 

6

 

Regulatory liabilities - current

 

 

201

 

 

 

205

 

Monetization of guaranty settlement(13)

 

 

568

 

 

 

635

 

Income taxes refundable through future rates(14)

 

 

820

 

 

 

839

 

Asset removal costs(16)

 

 

598

 

 

 

633

 

Reserve for refunds to electric utility customers(15)

 

 

161

 

 

 

237

 

Derivatives(11)

 

 

328

 

 

 

229

 

Other

 

 

13

 

 

 

6

 

Regulatory liabilities - noncurrent

 

 

2,488

 

 

 

2,579

 

Total regulatory liabilities

 

$

2,689

 

 

$

2,784

 
(1)
Reflects expenditures associated with the NND Project, which pursuant to the SCANA Merger Approval Order, will be recovered from electric service customers over a 20-year period ending in 2039.
(2)
Represents uncollected costs, including deferred depreciation and accretion expense, related to legal obligations associated with the future retirement of generation, transmission and distribution properties. The AROs primarily relate to DESC’s electric generating facilities, including Summer, and are expected to be recovered over the related property lives and periods of decommissioning which may range up to approximately 105 years. In addition, the balance at December 31, 2024 reflects amounts related to the EPA’s May 2024 final rule concerning CCR as discussed in Note 12.
(3)
Employee benefit plan costs have historically been recovered as they have been recorded under GAAP. Deferred employee benefit plan costs represent amounts of pension and other postretirement benefit costs which were accrued as liabilities and treated as regulatory assets pursuant to FERC guidance, and costs deferred pursuant to specific South Carolina Commission regulatory orders. DESC expects to recover deferred pension costs through utility rates over periods through 2044. DESC expects to recover other deferred benefit costs through utility rates, primarily over average service periods of participating employees up to 11 years.
(4)
Represents the carrying value of coal-fired generating units, including related materials and supplies inventory, retired from service prior to being fully depreciated. DESC is amortizing these amounts through cost of service rates following depreciation amounts that were designed to recover the retired units cost over their previous estimated remaining useful lives, which has been estimated to be through 2025. Based on current projections of remaining decommissioning costs, projected recovery is expected to extend through 2039. In addition, amounts include unrecovered costs of existing meters and equipment retired from service prior to being fully depreciated as part of the Advanced Metering Infrastructure project, which are being recovered through rates through 2028. This amount also includes certain inventory and preliminary survey and investigation charges being amortized through 2026 related to the transition or conversion from coal to gas fired generation at certain facilities.
(5)
Primarily represents deferred costs associated with electric demand reduction programs, and such deferred costs are currently being recovered over three years through an approved rate rider.
(6)
Represents amounts under- or over-collected from customers pursuant to the cost of fuel and purchased gas components approved by the South Carolina Commission.
(7)
Represents settled interest rate derivatives designated as cash flow hedges expected to be amortized to interest expense over the lives of the underlying debt through 2065.
(8)
Reflects amounts associated with the assessment and clean-up of sites currently or formerly owned by DESC. Such remediation costs are expected to be recovered over periods of up to 24 years. See Note 12 for additional information.
(9)
Represents storm restoration costs for which DESC expects to receive future recovery. Pursuant to the settlement agreement approved in DESC’s retail electric base rate case in August 2024, for costs incurred prior to September 2024, DESC expects to receive future recovery through customer rates through 2034 and for costs incurred effective September 2024, DESC expects to receive future recovery through customer rates of approximately $2 million each year. Unamortized amounts are included in rate base and are earning a current return.
(10)
Includes deferred depreciation and property taxes associated with certain transmission assets for which DESC expects future recovery from customers through 2062. Unamortized amounts are included in rate base and earning a current return.
(11)
Represents changes in the fair value of derivatives, excluding separately presented interest rate hedges, that following settlement are expected to be recovered from or refunded to customers.
(12)
Various other regulatory assets are expected to be recovered through rates over varying periods through 2078.
(13)
Represents proceeds related to the monetization of the Toshiba Settlement. In accordance with the SCANA Merger Approval Order, this balance, net of amounts that may be required to satisfy liens, will be refunded to electric customers over a 20-year period ending in 2039.
(14)
Includes (i) excess deferred income taxes arising from the remeasurement of deferred income taxes in connection with the enactment of the 2017 Tax Reform Act (certain of which are protected under normalization rules and will be amortized over the remaining lives of related property, and certain of which will be amortized to the benefit of customers over prescribed periods as instructed by regulators) and (ii) deferred income taxes arising from investment tax credits, offset by (iii) deferred income taxes that arise from utility operations that have not been included in customer rates (a portion of which relate to depreciation and are expected to be recovered over the remaining lives of the related property which may range up to 85 years). See Note 7 for additional information.
(15)
Reflects amounts previously collected from retail electric customers of DESC for the NND Project to be credited to customers over an estimated 11-year period effective February 2019 in connection with the SCANA Merger Approval Order.
(16)
Represents estimated net collections through depreciation rates of amounts to be expended for the removal of assets in the future.

 

Regulatory assets have been recorded based on the probability of their recovery. All regulatory assets represent incurred costs that may be deferred under GAAP for regulated operations. The South Carolina Commission or FERC has reviewed and approved through specific orders certain of the items shown as regulatory assets. In addition, regulatory assets include, but are not limited to, certain costs which have not been specifically approved for recovery by one of these regulatory agencies. While such costs are not currently being recovered, management believes that they would be allowable under existing rate-making concepts embodied in rate orders or applicable state law and expects to recover these costs through rates in future periods.
v3.25.0.1
Operating Revenue
 12 Months Ended
Dec. 31, 2024
Revenues [Abstract]  
Operating Revenue

4. OPERATING REVENUE

DESC’s operating revenue consists of the following:

 

Year Ended December 31,

 

2024

 

 

2023

 

 

2022

 

(millions)

 

Electric

 

 

Gas

 

 

Electric

 

 

Gas

 

 

Electric

 

 

Gas

 

Customer class:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Residential

 

$

1,259

 

 

$

302

 

 

$

1,160

 

 

$

268

 

 

$

1,375

 

 

$

303

 

Commercial

 

 

855

 

 

 

126

 

 

 

820

 

 

 

129

 

 

 

968

 

 

 

184

 

Industrial

 

 

389

 

 

 

68

 

 

 

372

 

 

 

77

 

 

 

533

 

 

 

166

 

Other

 

 

123

 

 

 

25

 

 

 

150

 

 

 

24

 

 

 

203

 

 

 

23

 

Revenues from contracts with customers

 

 

2,626

 

 

 

521

 

 

 

2,502

 

 

 

498

 

 

 

3,079

 

 

 

676

 

Other revenues

 

 

25

 

 

 

1

 

 

 

27

 

 

 

1

 

 

 

27

 

 

 

1

 

Total Operating Revenues

 

$

2,651

 

 

$

522

 

 

$

2,529

 

 

$

499

 

 

$

3,106

 

 

$

677

 

 

Contract liabilities represent the obligation to transfer goods or services to a customer for which consideration has already been received from the customer. DESC had contract liability balances of $6 million and $7 million at December 31, 2024 and 2023, respectively. For the years ended December 31, 2024 and 2023, DESC recognized revenue of $5 million and $9 million, respectively, from the beginning contract liability balances as DESC fulfilled its obligations to provide service to its customers. Contract liabilities are recorded in customer deposits and customer prepayments in the Consolidated Balance Sheets.

Contract Costs

In limited instances, DESC provides economic development grants intended to support economic growth within DESC’s electric service territory and defers such grants as regulatory assets on the Consolidated Balance Sheets. Whenever these grants are contingent on a customer entering into a long-term electric supply contract with DESC such costs are deferred and amortized on a straight-line basis over the term of the related service contract, which generally ranges from ten to 15 years.

Balances and activity related to contract costs deferred as regulatory assets were as follows:

 

 

Regulatory Assets

 

(millions)

 

2024

 

 

2023

 

Beginning balance

 

$

11

 

 

$

9

 

Additional costs

 

 

—

 

 

 

3

 

Amortization

 

 

(1

)

 

 

(1

)

Ending balance

 

$

10

 

 

$

11

 
v3.25.0.1
Equity
 12 Months Ended
Dec. 31, 2024
Stockholders' Equity Note [Abstract]  
Equity

5. EQUITY

For all periods presented, DESC’s authorized shares of common stock, no par value, were 50 million, of which 40.3 million were issued and outstanding, and DESC’s authorized shares of preferred stock, no par value, were 20 million, of which 1,000 shares were issued and outstanding. All outstanding shares of common and preferred stock are held by SCANA.

In 2022, Dominion Energy issued $72 million of shares of Dominion Energy common stock to partially satisfy DESC’s remaining obligation under a settlement agreement with the SCDOR discussed in Note 12. In connection with this transaction, DESC recorded an equity contribution from Dominion Energy.

DESC’s bond indenture under which it issues first mortgage bonds contains provisions that could limit the payment of cash dividends on its common stock. DESC’s bond indenture permits the payment of dividends on DESC’s common stock only either (1) out of its Surplus (as defined in the bond indenture) or (2) in case there is no Surplus, out of its net profits for the fiscal year in which the dividend is declared and/or the preceding fiscal year. In addition, pursuant to the SCANA Merger Approval Order, the amount of any DESC dividends paid must be reasonable and consistent with the long-term payout ratio of the electric utility industry and gas distribution industry.

At December 31, 2024, DESC’s retained earnings exceed the balance established by the Federal Power Act as a reserve on earnings attributable to hydroelectric generation plants. As a result, DESC is permitted to pay dividends without additional regulatory approval provided that such amounts would not bring the retained earnings balance below the established threshold.
v3.25.0.1
Long-Term and Short-Term Debt
 12 Months Ended
Dec. 31, 2024
Debt Disclosure [Abstract]  
Long-Term and Short-Term Debt

6. LONG-TERM AND SHORT-TERM DEBT

Long-term debt by type with related weighted-average coupon rates and maturities at December 31, 2024 and 2023 is as follows:

 

At December 31,

 

2024
Weighted-
average
Coupon(1)

 

 

2024

 

 

2023

 

(millions, except percentages)

 

 

 

 

 

 

 

 

 

DESC:

 

 

 

 

 

 

 

 

 

First Mortgage Bonds, 2.30% to 6.625%, due 2028 to 2065

 

 

5.23

%

 

$

4,134

 

 

$

4,134

 

Tax-Exempt Financings:(2)

 

 

 

 

 

 

 

 

 

Variable rate due 2038

 

 

3.70

%

 

 

35

 

 

 

35

 

3.625% and 4.00%, due 2028 and 2033

 

 

3.90

%

 

 

54

 

 

 

54

 

Other

 

 

3.58

%

 

 

1

 

 

 

1

 

GENCO:

 

 

 

 

 

 

 

 

 

Tax-Exempt Financing, variable rate due 2038

 

 

3.70

%

 

 

33

 

 

 

33

 

Affiliated note, 5.31% due 2027

 

 

5.31

%

 

 

230

 

 

 

230

 

Total principal

 

 

 

 

 

4,487

 

 

 

4,487

 

Affiliated and related party payables

 

 

 

 

 

—

 

 

 

(230

)

Unamortized discount, premium and debt issuance costs, net

 

 

 

 

 

(37

)

 

 

(38

)

Finance leases

 

 

 

 

 

2

 

 

 

4

 

Total long-term debt

 

 

 

 

$

4,452

 

 

$

4,223

 
(1)
Represents weighted-average coupon rates for debt outstanding as of December 31, 2024.
(2)
Industrial revenue bonds totaling $68 million are secured by letters of credit that expire, subject to renewal, in the fourth quarter of 2025.

 

Based on stated maturity dates rather than early redemption dates that could be elected by instrument holders, the scheduled principal payments of long-term debt at December 31, 2024, were as follows:

 

(millions, except percentages)

 

2025

 

 

2026

 

 

2027

 

 

2028

 

 

2029

 

 

Thereafter

 

 

Total

 

First Mortgage Bonds

 

$

—

 

 

$

—

 

 

$

—

 

 

$

53

 

 

$

—

 

 

$

4,081

 

 

$

4,134

 

Tax-Exempt Financings

 

 

—

 

 

 

—

 

 

 

—

 

 

 

39

 

 

 

—

 

 

 

83

 

 

 

122

 

Other

 

 

—

 

 

 

—

 

 

 

230

 

 

 

—

 

 

 

—

 

 

 

1

 

 

 

231

 

Total

 

$

—

 

 

$

—

 

 

$

230

 

 

$

92

 

 

$

—

 

 

$

4,165

 

 

$

4,487

 

Weighted-average coupon

 

 

 

 

 

 

 

 

5.31

%

 

 

4.14

%

 

 

 

 

 

5.21

%

 

 

 

Substantially all of DESC’s electric utility plant is pledged as collateral in connection with long-term debt.

DESC is subject to a bond indenture dated April 1, 1993 (Mortgage) covering substantially all of its electric properties under which all of its first mortgage bonds (Bonds) have been issued. Bonds may be issued under the Mortgage in an aggregate principal amount not exceeding the sum of (1) 70% of Unfunded Net Property Additions (as therein defined), (2) the aggregate principal amount of retired Bonds and (3) cash deposited with the trustee. Bonds, other than certain Bonds issued on the basis of retired Bonds, may be issued under the Mortgage only if Adjusted Net Earnings (as therein defined) for 12 consecutive months out of the 18 months immediately preceding the month of issuance are at least twice the annual interest requirements on all outstanding Bonds and Bonds to be issued (Bond Ratio). For the year ended December 31, 2024, the Bond Ratio was approximately 5.

In May 2024, following approval from the South Carolina Commission, GENCO amended its $230 million promissory note due to Dominion Energy to change the maturity date from May 2024 to May 2027 and the interest rate from 3.05% to 5.31%.

In January 2025, DESC issued $450 million of 5.30% first mortgage bonds that mature in 2035. The proceeds were used for general corporate purposes and/or to repay short-term debt.

Short-Term Debt

DESC’s short-term financing is supported through its access as co-borrower to Dominion Energy’s $6.0 billion joint revolving credit facility, which can be used for working capital, as support for the combined commercial paper programs of DESC, Dominion Energy, Virginia Power and Questar Gas (through May 2024) and for other general corporate purposes.

DESC’s share of commercial paper and letters of credit outstanding under its joint credit facility with Dominion Energy, were as follows:

 

(millions)

 

Facility Limit

 

 

Outstanding
Commercial
Paper(1)

 

 

Outstanding
Letters of
Credit

 

At December 31, 2024

 

 

 

 

 

 

 

 

 

Joint revolving credit facility(2)(3)

 

$

1,000

 

 

$

250

 

 

$

—

 

At December 31, 2023

 

 

 

 

 

 

 

 

 

Joint revolving credit facility(2)

 

$

1,000

 

 

$

254

 

 

$

—

 
(1)
The weighted-average interest rate of the outstanding commercial paper supported by the credit facility was 4.76% and 5.70% at December 31, 2024 and 2023, respectively.
(2)
A maximum of $1.0 billion of the facility is available to DESC, assuming adequate capacity is available after giving effect to uses by co-borrowers Dominion Energy and Virginia Power. A sub-limit for DESC is set within the facility limit but can be changed at the option of the co-borrowers multiple times per year. At December 31, 2024, the sub-limit for DESC was $500 million. If DESC has liquidity needs in excess of its sub-limit, the sub-limit may be changed or such needs may be satisfied through short-term borrowings from Dominion Energy. This credit facility matures in June 2026, with the potential to be extended by the borrowers to June 2028. The credit facility can be used to support bank borrowings and the issuance of commercial paper, as well as to support up to $1.0 billion (or the sub-limit, whichever is less) of letters of credit.
(3)
In May 2024, the joint revolving credit facility was amended to remove Questar Gas as a co-borrower.

In March 2023, FERC granted DESC authority through March 2025 to issue short-term indebtedness (pursuant to Section 204 of the Federal Power Act) in amounts not to exceed $2.2 billion outstanding with maturity dates of one year or less. At December 31, 2024, DESC had issued $250 million in commercial paper under its joint credit facility with Dominion Energy as disclosed above and had drawn on $597 million of its intercompany credit facility with Dominion Energy, as permitted by this FERC authorization. In addition, in March 2023, FERC granted GENCO authority through March 2025 to issue short-term indebtedness not to exceed $200 million outstanding with maturity dates of one year or less. At December 31, 2024, GENCO had drawn on $62 million of its intercompany credit facility with Dominion Energy, as permitted by this FERC authorization. In January 2025, DESC and GENCO applied to FERC for a two-year short-term borrowing authorization in amounts not to exceed $1.8 billion and $300 million, respectively. The applications are pending.

DESC is obligated with respect to an aggregate of $68 million of industrial revenue bonds which are secured by letters of credit. These letters of credit expire, subject to renewal, in the fourth quarter of 2025.

DESC, GENCO and Fuel Company each have intercompany credit facilities with Dominion Energy with a maximum capacity of $900 million, $200 million and $400 million, respectively. At December 31, 2024 and 2023, DESC, GENCO and Fuel Company collectively had borrowings outstanding under these agreements totaling $942 million and $442 million, respectively, which are recorded in affiliated and related party payables in DESC’s Consolidated Balance Sheets. For the years ended December 31, 2024, 2023 and 2022, DESC recorded interest charges of $50 million, $53 million and $19 million, respectively.
v3.25.0.1
Income Taxes
 12 Months Ended
Dec. 31, 2024
Income Tax Disclosure [Abstract]  
Income Taxes

7. INCOME TAXES

Judgment and the use of estimates are required in developing the provision for income taxes and reporting of tax-related assets and liabilities. The interpretation of tax laws involves uncertainty since tax authorities may interpret the laws differently. DESC is routinely audited by federal and state tax authorities. Ultimate resolution of income tax matters may result in favorable or unfavorable impacts to net income and cash flows, and adjustments to tax-related assets and liabilities could be material.

As indicated in Note 2, DESC’s operations, including accounting for income taxes, are subject to regulatory accounting treatment. See Note 3 for additional information and current year developments.

Details of income tax expense for continuing operations including noncontrolling interests were as follows:

 

Year Ended December 31,

 

2024

 

 

2023

 

 

2022

 

(millions)

 

 

 

 

 

 

 

 

 

Current:

 

 

 

 

 

 

 

 

 

Federal

 

$

(6

)

 

$

91

 

 

$

(69

)

State

 

 

7

 

 

 

(70

)

 

 

(3

)

Total current expense (benefit)

 

 

1

 

 

 

21

 

 

 

(72

)

Deferred:

 

 

 

 

 

 

 

 

 

Federal

 

 

 

 

 

 

 

 

 

Taxes before operating loss carryforwards and investment tax credits

 

 

16

 

 

 

(72

)

 

 

135

 

Tax utilization expense (benefit) of operating loss carryforwards

 

 

36

 

 

 

43

 

 

 

33

 

State

 

 

13

 

 

 

95

 

 

 

36

 

Total deferred expense

 

 

65

 

 

 

66

 

 

 

204

 

Investment tax credits

 

 

(1

)

 

 

(2

)

 

 

(1

)

Total income tax expense

 

$

65

 

 

$

85

 

 

$

131

 

 

Subsequent to the SCANA Combination, DESC’s annual utilization of its net operating losses is restricted by the tax law, however in certain circumstances the utilization may be increased if SCANA recognizes built-in gains on certain sales of assets.

For continuing operations including noncontrolling interests, the statutory U.S. federal income tax rate reconciles to DESC’s effective income tax rate as follows:

 

Year Ended December 31,

 

2024

 

 

2023

 

 

2022

 

U.S. statutory rate

 

 

21.0

%

 

 

21.0

%

 

 

21.0

%

Increases (reductions) resulting from:

 

 

 

 

 

 

 

 

 

State taxes, net of federal benefit

 

 

4.0

 

 

 

4.1

 

 

 

4.7

 

Amortization of federal investment tax credits

 

 

(0.3

)

 

 

(0.3

)

 

 

(0.2

)

Reversal of excess deferred income taxes

 

 

(5.6

)

 

 

(4.7

)

 

 

(4.6

)

Settlements of uncertain tax positions

 

 

(3.5

)

 

 

(2.2

)

 

 

—

 

Other

 

 

(0.1

)

 

 

(0.2

)

 

 

(0.2

)

Effective tax rate

 

 

15.5

%

 

 

17.7

%

 

 

20.7

%

 

DESC’s 2024 effective tax rate reflects an income tax benefit of $14 million from the effective settlement of a position that management believed was reasonably possible to occur.

 

DESC’s 2023 effective tax rate reflects an income tax benefit of $11 million from the effective settlement of a position that management believed was reasonably possible to occur.

 

DESC’s deferred income taxes consist of the following:

 

At December 31,

 

2024

 

 

2023

 

(millions)

 

 

 

 

 

 

Deferred income taxes:

 

 

 

 

 

 

Total deferred income tax assets

 

$

662

 

 

$

728

 

Total deferred income tax liabilities

 

 

2,059

 

 

 

2,033

 

Total net deferred income tax liabilities

 

$

1,397

 

 

$

1,305

 

Total deferred income taxes:

 

 

 

 

 

 

Depreciation method and plant basis differences

 

$

1,271

 

 

$

1,203

 

Excess deferred income taxes

 

 

(203

)

 

 

(212

)

Unrecovered nuclear plant cost

 

 

420

 

 

 

450

 

DESC rate refund

 

 

(49

)

 

 

(67

)

Toshiba Settlement

 

 

(133

)

 

 

(147

)

Nuclear decommissioning

 

 

(60

)

 

 

(51

)

Deferred state income taxes

 

 

289

 

 

 

274

 

Federal benefit of deferred state income taxes

 

 

(61

)

 

 

(60

)

Deferred fuel, purchased energy and gas costs

 

 

11

 

 

 

32

 

Pension benefits

 

 

35

 

 

 

35

 

Other postretirement benefits

 

 

(20

)

 

 

(17

)

Loss and credit carryforwards

 

 

(153

)

 

 

(185

)

Other

 

 

50

 

 

 

50

 

Total net deferred income tax liabilities

 

$

1,397

 

 

$

1,305

 

Deferred investment tax credits

 

 

12

 

 

 

13

 

Total deferred taxes and deferred investment tax credits

 

$

1,409

 

 

$

1,318

 

At December 31, 2024, DESC had the following deductible loss and credit carryforwards:

 

(millions)

 

Deductible Amount

 

 

Deferred Tax Asset(1)

 

 

Expiration Period

Federal losses

 

$

361

 

 

$

76

 

 

2037

Federal production and other credits

 

 

—

 

 

 

22

 

 

2036-2038

State losses

 

 

887

 

 

 

44

 

 

2037-2042

State investment and other credits

 

 

—

 

 

 

41

 

 

2026-2033

Total

 

$

1,248

 

 

$

183

 

 

 
(1)
Includes $38 million of unrecognized tax benefits.

A reconciliation of changes in DESC’s unrecognized tax benefits follows:

 

(millions)

 

2024

 

 

2023

 

 

2022

 

Balance at January 1,

 

$

62

 

 

$

68

 

 

$

62

 

Increases-prior period positions

 

 

5

 

 

 

5

 

 

 

6

 

Decreases-prior period positions

 

 

(16

)

 

 

(11

)

 

 

(1

)

Increases-current period positions

 

 

—

 

 

 

—

 

 

 

1

 

Settlements with tax authorities

 

 

(13

)

 

 

—

 

 

 

—

 

Balance at December 31,

 

$

38

 

 

$

62

 

 

$

68

 

Certain unrecognized tax benefits, or portions thereof, if recognized, would affect the effective tax rate. Changes in these unrecognized tax benefits may result from remeasurement of amounts expected to be realized, settlements with tax authorities and expiration of statutes of limitations. If recognized, all the unrecognized tax benefits would impact the effective tax rate.

The statute is closed for IRS examination of years prior to 2020. DESC is no longer subject to state and local income tax examinations by tax authorities for years prior to 2021.

It is reasonably possible that these unrecognized tax benefits may decrease by $38 million within the next twelve months. If such changes were to occur, other than revisions of the accrual for interest on tax underpayments and overpayments, earnings could increase by $30 million. Otherwise, with regard to 2024 and prior years, DESC cannot estimate the range of reasonably possible changes to unrecognized tax benefits that may occur in 2025.

DESC is also obligated to report adjustments resulting from IRS settlements to state tax authorities. In addition, if DESC utilizes operating losses or tax credits generated in years for which the statute of limitations has expired, such amounts are generally subject to examination.
v3.25.0.1
Derivative Financial Instruments
 12 Months Ended
Dec. 31, 2024
Derivative Instruments and Hedging Activities Disclosure [Abstract]  
Derivative Financial Instruments

8. DERIVATIVE FINANCIAL INSTRUMENTS

See Note 2 for DESC’s accounting policies, objectives, and strategies for using derivative instruments. See Notes 2 and 9 for further information about fair value measurements and associated valuation methods for derivatives.

Cash collateral is used in the table below to offset derivative assets and liabilities when applicable. Certain of DESC’s derivative instruments contain credit-related contingent provisions. These provisions require DESC to provide collateral upon the occurrence of specific events, primarily a credit rating downgrade. If the credit-related contingent features underlying the instruments that are in a liability position and not fully collateralized with cash were fully triggered as of December 31, 2024 and 2023, DESC would have been required to post $1 million and $4 million, respectively, of additional collateral to its counterparties. The collateral that would be required to be posted includes the impacts of any offsetting asset positions and any amounts already posted for derivatives and non-derivative contracts, per contractual terms. DESC had not posted any collateral at December 31, 2024 and 2023 related to derivatives with credit-related contingent provisions that are in a liability position and not fully collateralized with cash. The aggregate fair value of all derivative instruments with credit-related contingent provisions that are in a liability position and not fully collateralized with cash as of December 31, 2024 and 2023 was $1 million and $4 million, respectively, which does not include the impact of any offsetting asset positions.

The table below presents derivative balances by type of financial instrument, if the gross amounts recognized in the Consolidated Balance Sheets were netted with derivative instruments and cash collateral received or paid.

 

 

December 31, 2024

 

 

December 31, 2023

 

 

 

 

 

 

Gross Amounts Not Offset
in the Consolidated
Balance Sheet(1)

 

 

 

 

 

 

 

 

Gross Amounts Not Offset
in the Consolidated
Balance Sheet(1)

 

 

 

 

(millions)

 

Gross Assets
Presented in the
Consolidated
Balance Sheet

 

 

Financial
Instruments

 

 

Cash
Collateral
Received

 

 

Net
Amounts

 

 

Gross Assets
Presented in the
Consolidated
Balance Sheet

 

 

Financial
Instruments

 

 

Cash
Collateral
Received

 

 

Net
Amounts

 

Interest rate contracts:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Over-the-counter

 

$

2

 

 

$

—

 

 

$

—

 

 

$

2

 

 

$

—

 

 

$

—

 

 

$

—

 

 

$

—

 

Commodity contracts:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Over-the-counter

 

 

81

 

 

 

—

 

 

 

—

 

 

 

81

 

 

 

 

 

 

 

 

 

 

 

 

 

Total derivatives

 

$

83

 

 

$

—

 

 

$

—

 

 

$

83

 

 

$

—

 

 

$

—

 

 

$

—

 

 

$

—

 

(1) Excludes derivative assets of $289 million and $176 million at December 31, 2024 and December 31, 2023, respectively, which are not subject to master netting or similar arrangements.

 

 

 

December 31, 2024

 

 

December 31, 2023

 

 

 

 

 

 

Gross Amounts Not Offset
in the Consolidated
Balance Sheet(1)

 

 

 

 

 

 

 

 

Gross Amounts Not Offset
in the Consolidated
Balance Sheet(1)

 

 

 

 

(millions)

 

Gross
Liabilities
Presented in the
Consolidated
Balance Sheet

 

 

Financial
Instruments

 

 

Cash
Collateral
Paid

 

 

Net
Amounts

 

 

Gross
Liabilities
Presented in the
Consolidated
Balance Sheet

 

 

Financial
Instruments

 

 

Cash
Collateral
Paid

 

 

Net
Amounts

 

Interest rate contracts:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Over-the-counter

 

$

1

 

 

$

—

 

 

$

—

 

 

$

1

 

 

$

4

 

 

$

—

 

 

$

—

 

 

$

4

 

Total derivatives

 

$

1

 

 

$

—

 

 

$

—

 

 

$

1

 

 

$

4

 

 

$

—

 

 

$

—

 

 

$

4

 

(1) DESC did not have any derivative liabilities at December 31, 2024 and December 31, 2023, respectively, which were not subject to master netting or similar arrangements.

Volumes

The following table presents the volume of derivative activity at December 31, 2024. These volumes are based on open derivative positions and represent the combined absolute value of their long and short positions.

 

 

 

Current

 

 

Noncurrent

 

 

 

 

 

 

 

 

Natural Gas (bcf):

 

 

 

 

 

 

Basis(1)

 

 

32

 

 

 

30

 

Electricity (MWh in millions):

 

 

 

 

 

 

Fixed price

 

 

2

 

 

 

21

 

Interest rate(2) (in millions)

 

$

—

 

 

$

71

 
(1)
Includes options.
(2)
Maturity is determined based on final settlement period.

Fair Value and Gains and Losses on Derivative Instruments

The following table presents the fair values of derivatives and where they are presented in the Consolidated Balance Sheets:

 

 

Assets

 

Liabilities

 

(millions)

 

 

 

 

At December 31, 2024

 

 

 

 

Current derivatives not under cash flow hedge accounting

 

 

 

 

Commodity

$

63

 

$

—

 

Total current derivatives

$

63

 

$

—

 

Noncurrent derivatives not under cash flow hedge accounting

 

 

 

 

Commodity

$

307

 

$

—

 

Interest rate

 

2

 

 

1

 

Total noncurrent derivatives

 

309

 

 

1

 

Total derivatives

$

372

 

$

1

 

At December 31, 2023

 

 

 

 

Current derivatives not under cash flow hedge accounting

 

 

 

 

Commodity

$

9

 

$

—

 

Total current derivatives

$

9

 

$

—

 

Noncurrent derivatives not under cash flow hedge accounting

 

 

 

 

Commodity

$

167

 

$

—

 

Interest rate

 

—

 

 

4

 

Total noncurrent derivatives

 

167

 

 

4

 

Total derivatives

$

176

 

$

4

 

The following tables present the gains and losses on derivatives, as well as where the associated activity is presented in the Consolidated Balance Sheets and Statements of Comprehensive Income:

Derivatives in Cash Flow Hedging Relationships

(millions)

 

Increase (Decrease) in Derivatives Subject to Regulatory Treatment(1)

 

Year Ended December 31, 2024

 

 

 

Derivative type and location of gains (losses):

 

 

 

Interest rate

 

$

1

 

Total

 

$

1

 

Year Ended December 31, 2023

 

 

 

Derivative type and location of gains (losses):

 

 

 

Interest rate

 

$

—

 

Total

 

$

—

 

Year Ended December 31, 2022

 

 

 

Derivative type and location of gains (losses):

 

 

 

Interest rate

 

$

11

 

Total

 

$

11

 

 

(1)
Represents net derivative activity deferred into and amortized out of regulatory assets/liabilities. Amounts deferred into regulatory assets/ liabilities have no associated effect in the Consolidated Statements of Comprehensive Income.

Derivatives Not designated as Hedging Instruments

(millions)

 

Amount of Gain (Loss) Recognized in Income on Derivatives(1)

 

Year Ended December 31,

 

2024

 

 

2023

 

 

2022

 

Derivative type and location of gains (losses):

 

 

 

 

 

 

 

 

 

Commodity:

 

 

 

 

 

 

 

 

 

Purchased power

 

$

3

 

 

$

6

 

 

$

77

 

Fuel used in electric generation

 

 

1

 

 

 

—

 

 

 

—

 

Interest rate:

 

 

 

 

 

 

 

 

 

Interest charges

 

 

(1

)

 

 

(2

)

 

 

(2

)

Total

 

$

3

 

 

$

4

 

 

$

75

 
(1)
Includes derivative activity amortized out of regulatory assets/liabilities. Amounts deferred into regulatory assets/liabilities have no associated effect in the Consolidated Statements of Comprehensive Income.
v3.25.0.1
Fair Value Measurements, Including Derivatives
 12 Months Ended
Dec. 31, 2024
Fair Value Disclosures [Abstract]  
Fair Value Measurements, Including Derivatives

9. FAIR VALUE MEASUREMENTS, INCLUDING DERIVATIVES

DESC’s fair value measurements are made in accordance with the policies discussed in Note 2. See Note 8 for additional information about DESC’s derivative and hedge accounting activities.

Level 3 Valuations

DESC enters into certain physical forwards and options, which are considered Level 3 as they have one or more inputs that are not observable and are significant to the valuation. The discounted cash flow method is used to value Level 3 physical forwards contracts. The discounted cash flow model for forwards calculates mark-to-market valuations based on forward market prices, original transaction prices, volumes, risk-free rate of return and credit spreads. An option model is used to value Level 3 physical options. The inputs into the option models are the forward market prices, implied price volatilities, risk-free rate of return, the option expiration dates, the option strike prices, the original sales prices and volumes. For Level 3 fair value measurements, certain forward market prices are considered unobservable.

The following table presents DESC’s quantitative information about Level 3 fair value measurements at December 31, 2024. The range and weighted-average are presented in dollars for market price inputs and percentages for price volatility.

 

 

Fair Value (millions)

 

 

Valuation Techniques

 

Unobservable Input

 

Range

 

Weighted-average(1)

Assets

 

 

 

 

 

 

 

 

 

 

 

Physical forwards:

 

 

 

 

 

 

 

 

 

 

 

Electricity

 

$

289

 

 

Discounted cash flow

 

Market price (per MWh)(3)

 

31-95

 

55

Physical options:

 

 

 

 

 

 

 

 

 

 

 

Natural gas(2)

 

$

81

 

 

Option model

 

Market price (per Dth)(3)

 

2-7

 

4

 

 

 

 

 

 

 

Price volatility(4)

 

11%-73%

 

47%

Total assets

 

$

370

 

 

 

 

 

 

 

 

 
(1)
Averages weighted by volume.
(2)
Includes basis.
(3)
Represents market prices beyond defined terms for Levels 1 and 2.
(4)
Represents volatilities unrepresented in published markets.

Sensitivity of the fair value measurements to changes in the significant unobservable inputs is as follows:

Significant Unobservable Inputs

 

Position

 

Change to Input

 

Impact on Fair Value Measurement

Market price

 

Buy

 

Increase (decrease)

 

Gain (loss)

Market price

 

Sell

 

Increase (decrease)

 

Loss (gain)

Price volatility

 

Buy

 

Increase (decrease)

 

Gain (loss)

Price volatility

 

Sell

 

Increase (decrease)

 

Loss (gain)

 

Recurring Fair Value Measurements

Fair value disclosures for assets held in DESC’s pension plan are presented in Note 11.

The following table presents DESC’s assets and liabilities that are measured at fair value on a recurring basis for each hierarchy level, including both current and noncurrent portions:

 

 

Level 1

 

 

Level 2

 

 

Level 3

 

 

Total

 

(millions)

 

 

 

 

 

 

 

 

 

 

 

 

At December 31, 2024

 

 

 

 

 

 

 

 

 

 

 

 

Assets

 

 

 

 

 

 

 

 

 

 

 

 

Derivatives:

 

 

 

 

 

 

 

 

 

 

 

 

Commodity

 

$

—

 

 

$

—

 

 

$

370

 

 

$

370

 

Interest rate

 

 

—

 

 

 

2

 

 

 

—

 

 

 

2

 

Investments:

 

 

 

 

 

 

 

 

 

 

 

 

Cash equivalents and other

 

 

29

 

 

 

—

 

 

 

—

 

 

 

29

 

Total assets

 

$

29

 

 

$

2

 

 

$

370

 

 

$

401

 

Liabilities

 

 

 

 

 

 

 

 

 

 

 

 

Derivatives:

 

 

 

 

 

 

 

 

 

 

 

 

Interest rate

 

$

—

 

 

$

1

 

 

$

—

 

 

$

1

 

Total liabilities

 

$

—

 

 

$

1

 

 

$

—

 

 

$

1

 

At December 31, 2023

 

 

 

 

 

 

 

 

 

 

 

 

Assets

 

 

 

 

 

 

 

 

 

 

 

 

Derivatives:

 

 

 

 

 

 

 

 

 

 

 

 

Commodity

 

$

—

 

 

$

—

 

 

$

176

 

 

$

176

 

Total assets

 

$

—

 

 

$

—

 

 

$

176

 

 

$

176

 

Liabilities

 

 

 

 

 

 

 

 

 

 

 

 

Derivatives:

 

 

 

 

 

 

 

 

 

 

 

 

Interest rate

 

$

—

 

 

$

4

 

 

$

—

 

 

$

4

 

Total liabilities

 

$

—

 

 

$

4

 

 

$

—

 

 

$

4

 

The following table presents the net change in DESC’s assets and liabilities measured at fair value on a recurring basis and included in the Level 3 fair value category.

 

 

2024

 

 

2023

 

 

2022

 

(millions)

 

 

 

 

 

 

 

 

 

Balance at January 1,

 

$

176

 

 

$

251

 

 

$

148

 

Total realized and unrealized gains (losses):

 

 

 

 

 

 

 

 

 

Included in earnings:

 

 

 

 

 

 

 

 

 

Purchased power

 

 

3

 

 

 

6

 

 

 

77

 

Fuel used in electric generation

 

 

1

 

 

 

—

 

 

 

—

 

Gas purchased for resale

 

 

1

 

 

 

—

 

 

 

—

 

Included in regulatory assets/liabilities

 

 

115

 

 

 

(75

)

 

 

103

 

Settlements

 

 

(17

)

 

 

(6

)

 

 

(77

)

Purchases

 

 

91

 

 

 

—

 

 

 

—

 

Balance at December 31,

 

$

370

 

 

$

176

 

 

$

251

 

There are no unrealized gains and losses included in earnings in the Level 3 fair value category related to assets/liabilities still held at the reporting date for the years ended December 31, 2024, 2023 and 2022.

Fair Value of Financial Instruments

Substantially all of DESC’s financial instruments are recorded at fair value, with the exception of the instruments described below, which are reported at historical cost. Estimated fair values have been determined using available market information and valuation methodologies considered appropriate by management. The carrying amount of financial instruments classified within current assets and current liabilities are representative of fair value because of the short-term nature of these instruments. For financial instruments that are not recorded at fair value, the carrying amounts and estimated fair values are as follows:

 

At December 31,

 

2024

 

 

2023

 

(millions)

 

Carrying
Amount

 

 

Estimated
Fair Value(1)

 

 

Carrying
Amount

 

 

Estimated
Fair Value(1)

 

Long-term debt(2)

 

$

4,220

 

 

$

4,142

 

 

$

4,219

 

 

$

4,301

 

Affiliated long-term debt(3)

 

 

230

 

 

 

230

 

 

 

230

 

 

 

230

 
(1)
Fair value is estimated using market prices, where available, and interest rates currently available for issuance of debt with similar terms and remaining maturities. All fair value measurements are classified as Level 2. The carrying amount of debt issuances with short-term maturities and variable rates refinanced at current market rates is a reasonable estimate of their fair value.
(2)
Carrying amount includes current portions, if any, included in securities due within one year and amounts which represent the unamortized debt issuance costs and discount or premium.
(3)
Carrying amount includes current portions presented in affiliated and related party payables, as applicable.
v3.25.0.1
Asset Retirement Obligations
 12 Months Ended
Dec. 31, 2024
Asset Retirement Obligation Disclosure [Abstract]  
Asset Retirement Obligations

10. ASSET RETIREMENT OBLIGATIONS

A liability for the present value of an ARO is recognized when incurred if the liability can be reasonably estimated. Uncertainty about the timing or method of settlement of a conditional ARO is factored into the measurement of the liability when sufficient information exists, but such uncertainty is not a basis upon which to avoid liability recognition.

The legal obligations associated with the retirement of long-lived tangible assets that result from their acquisition, construction, development and normal operation relate primarily to DESC’s regulated utility operations. As of December 31, 2024 and 2023, DESC has recorded AROs of $324 million and $311 million, respectively, for nuclear plant decommissioning. In addition, DESC has recorded AROs of $815 million and $420 million at December 31, 2024 and 2023, respectively, for other conditional obligations primarily related to other generation including CCR, transmission and distribution properties, including gas pipelines. All of the amounts recorded are based upon estimates which are subject to varying degrees of precision, particularly since such payments are based on future cash flows for extended periods of time which are by nature highly uncertain.

A reconciliation of the beginning and ending aggregate carrying amount of AROs is as follows:

 

(millions)

 

2024

 

 

2023

 

Beginning balance

 

$

731

 

 

$

628

 

Liabilities incurred(1)

 

 

654

 

 

 

7

 

Liabilities settled

 

 

(79

)

 

 

(14

)

Accretion expense

 

 

46

 

 

 

29

 

Revisions in estimated cash flows(2)

 

 

(213

)

 

 

81

 

Ending balance

 

$

1,139

 

 

$

731

 
(1)
In 2024, primarily reflects AROs related to CCR remediation as discussed in Note 12.
(2)
In 2024, primarily reflects a revision related to CCR remediation costs as discussed in Note 12. In 2023, there was an increase in estimated costs associated with certain coal-fired generating units, including revisions following the approval of closure plans for a facility previously taken out of service.
v3.25.0.1
Employee Benefit Plans and Equity Compensation Plan
 12 Months Ended
Dec. 31, 2024
Retirement Benefits [Abstract]  
Employee Benefit Plans and Equity Compensation Plan

11. EMPLOYEE BENEFIT PLANS AND EQUITY COMPENSATION PLAN

Pension and Other Postretirement Benefit Plans

SCANA sponsors a noncontributory defined benefit pension plan covering regular, full-time employees hired before January 1, 2014. DESC participates in SCANA’s pension plan. SCANA’s policy has been to fund the plan as permitted by applicable federal income tax regulations, as determined by an independent actuary.

The pension plan provides benefits under a cash balance formula for employees hired before January 1, 2000 who elected that option and all eligible employees hired subsequently through December 31, 2013. Under the cash balance formula, benefits accumulate as a result of compensation credits and interest credits. Employees hired before January 1, 2000 who elected to remain under the final average pay formula earn benefits based on years of credited service and the employee’s average annual base earnings received during the last three years of employment. Benefits under the final average pay formula continued to accrue through December 31, 2023, after which date eligible participants began accruing benefits under the cash balance formula.

In addition to pension benefits, SCANA provides certain unfunded postretirement health care and life insurance benefits to certain active and retired employees. DESC participates in these programs. Retirees hired before January 1, 2011 share in a portion of their medical care cost, while employees hired subsequently are responsible for the full cost of retiree medical benefits elected by them. The costs of postretirement benefits other than pensions are accrued during the years the employees render the services necessary to be eligible for these benefits.

The same benefit formula applies to all SCANA subsidiaries participating in the parent sponsored plans and, with regard to the pension plan, there are no legally separate asset pools. The postretirement benefit plans are accounted for as multiple employer plans.

Changes in Benefit Obligations

The measurement date used to determine pension and other postretirement benefit obligations is December 31. Data related to the changes in the projected benefit obligation for pension benefits and the accumulated benefit obligation for other postretirement benefits are presented below.

 

 

 

Pension Benefits

 

 

Other Postretirement Benefits

 

(millions)

 

2024

 

 

2023

 

 

2024

 

 

2023

 

Beginning balance

 

$

584

 

 

$

580

 

 

$

120

 

 

$

121

 

Service cost

 

 

8

 

 

 

8

 

 

 

1

 

 

 

1

 

Interest cost

 

 

31

 

 

 

33

 

 

 

8

 

 

 

8

 

Amendments

 

 

7

 

 

 

1

 

 

 

—

 

 

 

—

 

Actuarial (gain) loss

 

 

(10

)

 

 

1

 

 

 

(6

)

 

 

1

 

Benefits paid

 

 

(43

)

 

 

(39

)

 

 

(11

)

 

 

(11

)

Ending balance

 

$

577

 

 

$

584

 

 

$

112

 

 

$

120

 

 

The accumulated benefit obligation for pension benefits for DESC was $574 million and $579 million at December 31, 2024 and 2023, respectively. The accumulated pension benefit obligation differs from the projected pension benefit obligation above in that it reflects no assumptions about future compensation levels.

Significant assumptions used to determine the above benefit obligations are as follows:

 

 

 

Pension Benefits

 

 

Other Postretirement Benefits

 

 

 

2024

 

 

2023

 

 

2024

 

 

2023

 

Annual discount rate used to determine benefit obligation

 

 

5.84

%

 

 

5.39

%

 

 

5.86

%

 

 

5.42

%

Assumed annual rate of future salary increases for projected
   benefit obligation

 

 

3.47

%

 

 

3.54

%

 

N/A

 

 

N/A

 

Crediting interest rate for cash balance plans

 

 

4.59

%

 

 

4.14

%

 

N/A

 

 

N/A

 

 

DESC’s pension benefit obligations include a gain of $10 million in 2024 resulting primarily from a $15 million gain due to an increase in the discount rate that was offset by a $5 million loss from other experience. DESC’s pension benefit obligations include a loss of $1 million in 2023 resulting primarily from a $10 million loss due to a decrease in the discount rate that was offset by a $9 million gain from other experience. Actuarial gains recognized in DESC’s other postretirement benefit obligations include a $6 million gain in 2024 resulting from a $7 million gain due to an increase in the discount rate that was offset by a $1 million loss from other experience. Actuarial losses recognized in DESC’s other postretirement benefit obligations include a $1 million loss in 2023 resulting from a $4 million loss due to a decrease in the discount rate that was offset by a $3 million gain from other experience.

 

A 7.00% annual rate of increase in the per capita cost of covered health care benefits was assumed for 2024. The rate was assumed to decrease gradually to 5.0% in 2032 and to remain at that level thereafter.

Funded Status

 

 

 

Pension Benefits

 

 

Other Postretirement Benefits

 

At December 31,

 

2024

 

 

2023

 

 

2024

 

 

2023

 

(millions)

 

 

 

 

 

 

 

 

 

 

 

 

Fair value of plan assets

 

$

603

 

 

$

588

 

 

$

—

 

 

$

—

 

Benefit obligation

 

 

577

 

 

 

584

 

 

 

112

 

 

 

120

 

Funded status

 

$

26

 

 

$

4

 

 

$

(112

)

 

$

(120

)

 

 

Amounts recognized on the consolidated balance sheets were as follows:

 

 

 

Pension Benefits

 

 

Other Postretirement Benefits

 

At December 31,

 

2024

 

 

2023

 

 

2024

 

 

2023

 

(millions)

 

 

 

 

 

 

 

 

 

 

 

 

Noncurrent assets

 

$

26

 

 

$

4

 

 

$

—

 

 

$

—

 

Current liability

 

 

—

 

 

 

—

 

 

 

(10

)

 

 

(11

)

Noncurrent liability

 

 

—

 

 

 

—

 

 

 

(102

)

 

 

(109

)

 

Amounts recognized in AOCI were as follows:

 

 

 

Pension Benefits

 

 

Other Postretirement Benefits

 

At December 31,

 

2024

 

 

2023

 

 

2024

 

 

2023

 

(millions)

 

 

 

 

 

 

 

 

 

 

 

 

Net actuarial (gain) loss

 

$

2

 

 

$

2

 

 

$

(1

)

 

$

(1

)

 

Amounts recognized in regulatory assets were as follows:

 

 

 

Pension Benefits

 

 

Other Postretirement Benefits

 

At December 31,

 

2024

 

 

2023

 

 

2024

 

 

2023

 

(millions)

 

 

 

 

 

 

 

 

 

 

 

 

Net actuarial (gain) loss

 

$

98

 

 

$

126

 

 

$

(43

)

 

$

(41

)

Prior service cost

 

 

7

 

 

 

1

 

 

 

—

 

 

 

—

 

Total

 

$

105

 

 

$

127

 

 

$

(43

)

 

$

(41

)

 

In connection with the joint ownership of Summer, costs related to pensions attributable to Santee Cooper as of December 31, 2024 and 2023 totaled $9 million and $19 million and were recorded within deferred debits. Costs related to other postretirement benefits attributable to Santee Cooper as of both December 31, 2024 and 2023 totaled $10 million were recorded within deferred debits.

Changes in Fair Value of Plan Assets

 

 

 

Pension Benefits

 

At December 31,

 

2024

 

 

2023

 

(millions)

 

 

 

 

 

 

Beginning balance

 

$

588

 

 

$

561

 

Actual return (loss) on plan assets

 

 

50

 

 

 

66

 

Benefits paid

 

 

(43

)

 

 

(39

)

Contributions

 

 

8

 

 

 

—

 

Ending balance

 

$

603

 

 

$

588

 

Investment Policies and Strategies

Strategic investment policies are established for DESC’s prefunded benefit plans based upon periodic asset/liability studies. Factors considered in setting the investment policy include employee demographics, liability growth rates, future discount rates, the funded status of the plans and the expected long-term rate of return on plan assets. Deviations from the plans’ strategic allocation are a function of DESC’s assessments regarding short-term risk and reward opportunities in the capital markets and/or short-term market movements which result in the plans’ actual asset allocations varying from the strategic target asset allocations. Through periodic rebalancing, actual allocations are brought back in line with the target. Future asset/liability studies will focus on strategies to further reduce pension and other postretirement plan risk, while still achieving attractive levels of returns. Financial derivatives may be used to obtain or manage market exposures and to hedge assets and liabilities.

DESC’s overall objective for investing its pension plan assets is to achieve appropriate long-term rates of return commensurate with prudent levels of risk. To minimize risk, funds are diversified among asset classes, securities, active and passive investment strategies and investment advisors. Effective January 2025, DESC transferred its pension assets to be held in Dominion Energy’s pension master trust. The strategic target asset allocations after the assets were moved to Dominion Energy’s pension master trust are expected to be: 30% public equity, 27% fixed income and 43% other alternative investments, such as private equity, private debt and hedge fund investments. The strategic target asset allocations for DESC’s pension fund through December 2024 were: 45% global equities, 53% fixed income and 2% cash. Global equities include investments in U.S. and non-U.S. companies, developed and emerging markets and small and large cap companies. The split between U.S. and non-U.S. companies was roughly 60% U.S./40% Non-U.S. Fixed income

includes investments in corporate debt instruments of companies from diversified industries and U.S. Treasuries. Equity and fixed income investments are in individual securities, mutual funds and exchange traded funds.

 

DESC also utilizes commingled funds/collective trust funds as an investment vehicle for its defined benefit plans. A commingled fund/collective trust fund is a pooled fund operated by a bank, trust company, or investment firm for investment of the assets of various organizations and individuals in a diversified portfolio. Commingled funds/collective trust funds are funds of grouped assets that follow various investment strategies.

For 2025, the expected long-term rate of return on assets will be 7.35%. DESC determines the expected long-term rates of return on plan assets for its pension plans by using a combination of:

•
Expected inflation and risk-free interest rate assumptions;
•
Historical return analysis to determine long term historic returns as well as historic risk premiums for various asset classes;
•
Expected future risk premiums, asset classes’ volatilities and correlations;
•
Forward-looking return expectations derived from the yield on long-term bonds and the expected long-term returns of major capital market assumptions; and
•
Investment allocation of plan assets.

Fair Value Measurements

Assets held by the pension plan are measured at fair value and are classified in their entirety based on the lowest level of input that is significant to the fair value measurement. At December 31, 2024 and 2023, fair value measurements, and the level within the fair value hierarchy in which the measurements fall, were as follows:

 

At December 31,

 

2024

 

 

2023

 

(millions)

 

Level 1

 

 

Level 2

 

 

Level 3

 

 

Total

 

 

Level 1

 

 

Level 2

 

 

Level 3

 

 

Total

 

Cash and cash equivalents

 

$

294

 

 

$

—

 

 

$

—

 

 

$

294

 

 

$

4

 

 

$

1

 

 

$

—

 

 

$

5

 

Corporate debt instruments

 

 

—

 

 

 

—

 

 

 

—

 

 

 

—

 

 

 

—

 

 

 

137

 

 

 

—

 

 

 

137

 

Government and other debt
   instruments

 

 

—

 

 

 

—

 

 

 

—

 

 

 

—

 

 

 

—

 

 

 

14

 

 

 

—

 

 

 

14

 

Total recorded at fair value

 

$

294

 

 

$

—

 

 

$

—

 

 

$

294

 

 

$

4

 

 

$

152

 

 

$

—

 

 

$

156

 

Assets recorded at NAV(1)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Commingled funds/collective
   trust funds

 

 

 

 

 

 

 

 

 

 

 

—

 

 

 

 

 

 

 

 

 

 

 

 

436

 

Total recorded at NAV

 

 

 

 

 

 

 

 

 

 

$

—

 

 

 

 

 

 

 

 

 

 

 

$

436

 

Total investments(2)

 

 

 

 

 

 

 

 

 

 

$

294

 

 

 

 

 

 

 

 

 

 

 

$

592

 
(1)
These investments that are measured at fair value using the NAV per share (or its equivalent) as a practical expedient are not required to be categorized in the fair value hierarchy.
(2)
Excludes net assets related to pending sales of securities of $309 million at December 31, 2024. Excludes net assets related to pending sales of securities of $1 million, net accrued income of $1 million, and includes net assets related to pending purchases of securities of $6 million at December 31, 2023.

 

For purposes of calculating NAV, portfolio securities and other assets for which market quotes are readily available are valued at market value. Short-term investment vehicles are funds that invest in short-term fixed income instruments and are valued using observable prices of the underlying fund assets based on trade data for identical or similar securities. U.S. Treasury securities are valued using quoted market prices or based on models using observable inputs from market sources such as external prices or spreads or benchmarked thereto. Corporate debt instruments and government and other debt instruments are valued based on recently executed transactions, using quoted market prices, or based on models using observable inputs from market sources such as external prices or spreads or benchmarked thereto. In addition, corporate debt instruments include investments in open-end mutual funds registered with the SEC that invest in corporate debt instruments. Commingled funds/common collective trust assets are valued at NAV, which are determined based on the unit values of the trust funds. Unit values are determined by the organization sponsoring such funds by dividing the funds’ net assets at fair value by the units outstanding at each valuation date.

Expected Cash Flows

Total benefits expected to be paid from the pension plan or company assets for the other postretirement benefits plan (net of participant contributions), respectively, are as follows:

Expected Benefit Payments

 

(millions)

 

Pension Benefits

 

 

Other Postretirement Benefits

 

2025

 

$

50

 

 

$

11

 

2026

 

 

46

 

 

 

11

 

2027

 

 

45

 

 

 

11

 

2028

 

 

47

 

 

 

11

 

2029

 

 

46

 

 

 

11

 

2030 - 2034

 

 

240

 

 

 

54

 

Pension Plan Contributions

Under its funding policies, DESC evaluates plan funding requirements annually, usually in the fourth quarter after receiving updated plan information from its actuary. Based on the funded status of each plan and other factors, DESC determines the amount of contributions for the current year, if any, at that time. DESC made $8 million of contributions, which were reimbursed by Santee Cooper, to the pension trust in 2024, and no such contributions in 2023 or 2022. DESC expects to make $3 million of minimum required contributions to its qualified pension plan in 2025 and expects to receive reimbursement for such contributions from Santee Cooper.

Net Periodic Benefit Cost

Net periodic benefit cost is recorded utilizing beginning of the year assumptions. Disclosures required for these plans are set forth in the following tables.

Components of Net Periodic Benefit (Credit) Cost

 

 

 

Pension Benefits

 

 

Other Postretirement Benefits

 

Year Ended December 31,

 

2024

 

 

2023

 

 

2022

 

 

2024

 

 

2023

 

 

2022

 

(millions)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Service cost

 

$

8

 

 

$

8

 

 

$

8

 

 

$

1

 

 

$

1

 

 

$

1

 

Interest cost

 

 

31

 

 

 

33

 

 

 

21

 

 

 

8

 

 

 

8

 

 

 

6

 

Expected return on assets

 

 

(37

)

 

 

(34

)

 

 

(49

)

 

 

—

 

 

 

—

 

 

 

—

 

Amortization of actuarial losses (gains)

 

 

9

 

 

 

12

 

 

 

1

 

 

 

(4

)

 

 

(4

)

 

 

—

 

Net periodic benefit (credit) cost

 

$

11

 

 

$

19

 

 

$

(19

)

 

$

5

 

 

$

5

 

 

$

7

 

 

In connection with regulatory orders, DESC recovers current pension costs through a rate rider that may be adjusted annually for retail electric operations or through cost of service rates for gas operations. For retail electric operations, current pension expense is recognized based on amounts collected through a rate rider, and differences between actual pension expense and amounts recognized pursuant to the rider are deferred as a regulatory asset (for under-collections) or regulatory liability (for over-collections) as applicable. In addition, DESC amortizes certain previously deferred pension costs. See Note 3.

Other changes in plan assets and benefit obligations recognized in other comprehensive income (net of tax) were as follows:

 

 

 

Pension Benefits

 

 

Other Postretirement Benefits

 

Year Ended December 31,

 

2024

 

 

2023

 

 

2022

 

 

2024

 

 

2023

 

 

2022

 

(millions)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Current year actuarial (gain) loss

 

$

—

 

 

$

(1

)

 

$

2

 

 

$

—

 

 

$

—

 

 

$

(1

)

Total recognized in other comprehensive income

 

$

—

 

 

$

(1

)

 

$

2

 

 

$

—

 

 

$

—

 

 

$

(1

)

 

Other changes in plan assets and benefit obligations recognized in regulatory assets were as follows:

 

 

 

Pension Benefits

 

 

Other Postretirement Benefits

 

Year Ended December 31,

 

2024

 

 

2023

 

 

2022

 

 

2024

 

 

2023

 

 

2022

 

(millions)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Current year actuarial (gain) loss

 

$

(20

)

 

$

(27

)

 

$

95

 

 

$

(5

)

 

$

2

 

 

$

(41

)

Amortization of actuarial gain (loss)

 

 

(8

)

 

 

(11

)

 

 

(1

)

 

 

3

 

 

 

3

 

 

 

—

 

Current year prior service cost

 

 

6

 

 

 

1

 

 

 

—

 

 

 

—

 

 

 

—

 

 

 

—

 

Total recognized in regulatory assets

 

$

(22

)

 

$

(37

)

 

$

94

 

 

$

(2

)

 

$

5

 

 

$

(41

)

 

Significant assumptions used in determining net periodic benefit cost:

 

 

 

Pension Benefits

 

 

Other Postretirement Benefits

 

Year Ended December 31,

 

2024

 

 

2023

 

 

2022

 

 

2024

 

 

2023

 

 

2022

 

Discount rate

 

 

5.39

%

 

 

5.69

%

 

 

3.06

%

 

 

5.42

%

 

 

5.70

%

 

 

3.11

%

Expected return on plan assets

 

 

7.00

%

 

 

7.00

%

 

 

7.00

%

 

n/a

 

 

n/a

 

 

n/a

 

Rate of compensation increase

 

 

3.54

%

 

 

3.93

%

 

 

3.71

%

 

n/a

 

 

n/a

 

 

n/a

 

Crediting interest rate for cash balance plans

 

 

4.14

%

 

 

4.44

%

 

 

1.81

%

 

n/a

 

 

n/a

 

 

n/a

 

Health care cost trend rate

 

 

 

 

 

 

 

 

 

 

 

7.00

%

 

 

7.00

%

 

 

6.25

%

Ultimate health care cost trend rate

 

 

 

 

 

 

 

 

 

 

 

5.00

%

 

 

5.00

%

 

 

5.00

%

Year achieved

 

 

 

 

 

 

 

 

 

 

2031

 

 

2030

 

 

2026-2027

 

 

Participation in Dominion Energy Defined Benefit Plans

Effective January 2021, eligible DESC employees hired after 2013 began accruing benefits under a cash balance formula within the Dominion Energy Pension Plan, a qualified defined benefit pension plan sponsored by Dominion Energy. In addition, DESC employees hired in 2021 prior to July 2021 are covered by the Dominion Energy Pension Plan. As a participating employer, DESC is subject to Dominion Energy’s funding policy, which is to contribute annually an amount that is in accordance with ERISA. DESC made no contributions to the Dominion Energy Pension Plan during 2024 or 2023. DESC made contributions of less than $1 million to the Dominion Energy Pension Plan during 2022. DESC’s net periodic pension cost related to this plan was $2 million, $2 million, and $1 million in 2024, 2023, and 2022, respectively. Net periodic benefit (credit) cost is reflected in other operations and maintenance expense in DESC’s Consolidated Statements of Income. The funded status of various Dominion Energy subsidiary groups and employee compensation are the basis for determining the share of total pension costs for participating Dominion Energy subsidiaries. During 2024 and 2023, DESC’s pension and other postretirement benefits obligation includes $7 million and $6 million, respectively, for amounts due to Dominion Energy related to this plan.

 

Dominion Energy holds investments in trusts to fund employee benefit payments for the pension plan in which DESC’s employees participate. Any investment-related declines in these trusts will result in future increases in the net periodic cost recognized for such employee benefit plans and will be included in the determination of the amount of cash that DESC will provide to Dominion Energy for its share of employee benefit plan contributions.

 

401(k) Retirement Savings Plan

Effective January 2021, DESC participates in a defined contribution savings plan sponsored by Dominion Energy. Previously, DESC had participated in a defined contribution plan sponsored by SCANA, which was merged into the Dominion Energy plan in December 2020. DESC recognized employer matching contributions of $15 million, $14 million, and $13 million in 2024, 2023, and 2022, respectively.
v3.25.0.1
Commitments And Contingencies
 12 Months Ended
Dec. 31, 2024
Commitments and Contingencies Disclosure [Abstract]  
Commitments and Contingencies

12. COMMITMENTS AND CONTINGENCIES

As a result of issues generated in the ordinary course of business, DESC is involved in legal proceedings before various courts and is periodically subject to governmental examinations (including by regulatory authorities), inquiries and investigations. Certain legal proceedings and governmental examinations involve demands for unspecified amounts of damages, are in an initial procedural phase, involve uncertainty as to the outcome of pending appeals or motions, or involve significant factual issues that need to be resolved, such that it is not possible for DESC to estimate a range of possible loss. For such matters that DESC cannot estimate, a statement to this effect is made in the description of the matter. Other matters may have progressed sufficiently through the litigation or investigative processes such that DESC is able to estimate a range of possible loss. For legal proceedings and governmental examinations that DESC is able to reasonably estimate a range of possible losses, an estimated range of possible loss is provided, in excess of the accrued liability (if any) for such matters. DESC maintains various insurance programs, including general liability insurance coverage which provides coverage for personal injury or wrongful death cases. Any accrued liability is recorded on a gross basis with a receivable also recorded for any probable insurance recoveries. Estimated ranges of loss are inclusive of legal fees and net of any anticipated insurance recoveries. Any estimated range is based on currently available information and involves elements of

judgment and significant uncertainties. Any estimated range of possible loss may not represent DESC’s maximum possible loss exposure. The circumstances of such legal proceedings and governmental examinations will change from time to time and actual results may vary significantly from the current estimate. For current proceedings not specifically reported below, management does not anticipate that the liabilities, if any, arising from such proceedings would have a material effect on DESC’s financial position, liquidity or results of operations. During the year ended December 31, 2024, DESC recorded $11 million of charges in aggregate for various personal injury or wrongful death cases. DESC’s Consolidated Balance Sheet at December 31, 2024 includes $10 million of insurance receivables and $7 million of reserves related to personal injury or wrongful death cases. The Consolidated Balance Sheets at December 31, 2023 included an inconsequential amount of reserves primarily related to personal injury or wrongful death cases. For the years ended December 31, 2023 and 2022, charges included in DESC’s Consolidated Statements of Comprehensive Income were inconsequential.

Environmental Matters

DESC is subject to costs resulting from a number of federal, state and local laws and regulations designed to protect human health and the environment. These laws and regulations affect future planning and existing operations. They can result in increased capital, operating and other costs as a result of compliance, remediation, containment and monitoring obligations.

 

From a regulatory perspective, DESC continually monitors and evaluates its current and projected emission levels and strives to comply with all state and federal regulations regarding those emissions. DESC participates in the SO2 and NOX emission allowance programs with respect to coal plant emissions and also has constructed additional pollution control equipment at its coal-fired electric generating plants. These actions are expected to address many of the rules and regulations discussed herein.

Air

The CAA, as amended, is a comprehensive program utilizing a broad range of regulatory tools to protect and preserve the nation’s air quality. At a minimum, states are required to establish regulatory programs to meet applicable requirements of the CAA. However, states may choose to develop regulatory programs that are more restrictive. Many of DESC’s facilities are subject to the CAA’s permitting and other requirements.

 

ACE Rule

In July 2019, the EPA published the final rule informally referred to as the ACE Rule, as a replacement for the Clean Power Plan. The ACE Rule regulated GHG emissions from existing coal-fired power plants pursuant to Section 111(d) of the CAA and required states to develop plans by July 2022 establishing unit-specific performance standards for existing coal-fired power plants. In January 2021, the U.S. Court of Appeals for the D.C. Circuit vacated the ACE Rule and remanded it to the EPA. This decision would take effect upon issuance of the court’s mandate. In March 2021, the court issued a partial mandate vacating and remanding all parts of the ACE Rule except for the portion of the ACE Rule that repealed the Clean Power Plan. In October 2021, the U.S. Supreme Court agreed to hear a challenge of the U.S. Court of Appeals for the D.C. Circuit’s decision on the ACE Rule. In June 2022, the U.S. Supreme Court reversed the D.C. Circuit’s decision on the ACE Rule and remanded the case back to the D.C. Circuit. In May 2024, the EPA repealed the ACE Rule as part of a package of final rules addressing CO2 emissions from new and existing fossil fuel-fired electric generating units.

 

Carbon Regulations

In August 2016, the EPA issued a draft rule proposing to reaffirm that a source’s obligation to obtain a PSD or Title V permit for GHGs is triggered only if such permitting requirements are first triggered by non-GHG, or conventional, pollutants that are regulated by the New Source Review program, and exceed a significant emissions rate of 75,000 tons per year of CO2 equivalent emissions. Until the EPA ultimately takes final action on this rulemaking, DESC cannot predict the impact to its results of operations, financial condition and/or cash flows.

In December 2018, the EPA proposed revised Standards of Performance for Greenhouse Gas Emissions from New, Modified, and Reconstructed Stationary Sources. The proposed rule would amend the previous determination that the best system of emission reduction for newly constructed coal-fired steam generating units is no longer partial carbon capture and storage. Instead, the proposed revised best system of emission reduction for this source category is the most efficient demonstrated steam cycle (e.g., supercritical steam conditions for large units and subcritical steam conditions for small units) in combination with best operating practices. In May 2024, the EPA withdrew the proposed revision to the performance standards for coal-fired steam generating units as part of a package of final rules addressing CO2 emissions from new and existing fossil fuel-fired electric generating units.

Water

The CWA, as amended, is a comprehensive program requiring a broad range of regulatory tools including a permit program to authorize and regulate discharges to surface waters with strong enforcement mechanisms. DESC must comply with applicable aspects of the CWA programs at its operating facilities.

Regulation 316(b)

In October 2014, the final regulations under Section 316(b) of the CWA that govern existing facilities and new units at existing facilities that employ a cooling water intake structure and that have flow levels exceeding a minimum threshold became effective. The rule establishes a national standard for impingement based on seven compliance options, but forgoes the creation of a single technology standard for entrainment. Instead, the EPA has delegated entrainment technology decisions to state regulators. State regulators are to make case-by-case entrainment technology determinations after an examination of five mandatory facility-specific factors, including a social cost-benefit test, and six optional facility-specific factors. The rule governs all electric generating stations with water withdrawals above two MGD, with a heightened entrainment analysis for those facilities over 125 MGD. DESC has five facilities that are subject to the final regulations. DESC is also working with the EPA and state regulatory agencies to assess the applicability of Section 316(b) to five hydroelectric facilities. DESC anticipates that it may have to install impingement control technologies at certain of these stations that have once-through cooling systems. DESC is currently evaluating the need or potential for entrainment controls under the final rule as these decisions will be made on a case-by-case basis after a thorough review of detailed biological, technological, and cost benefit studies. DESC is conducting studies and implementing plans as required by the rule to determine appropriate intake structure modifications at certain facilities to ensure compliance with this rule. While the impacts of this rule could be material to DESC’s results of operations, financial condition and/or cash flows, the existing regulatory framework in South Carolina provides rate recovery mechanisms that could substantially mitigate any such impacts for DESC.

 

Effluent Limitations Guidelines

In September 2015, the EPA released a final rule to revise the ELG Rule. The final rule established updated standards for wastewater discharges that apply primarily at coal and oil steam generating stations. Affected facilities are required to convert from wet to dry or closed cycle coal ash management, improve existing wastewater treatment systems and/or install new wastewater treatment technologies in order to meet the new discharge limits. In April 2017, the EPA granted two separate petitions for reconsideration of the final ELG Rule and stayed future compliance dates in the rule. Also in April 2017, the U.S. Court of Appeals for the Fifth Circuit granted the EPA’s request for a stay of the pending consolidated litigation challenging the rule while the EPA addresses the petitions for reconsideration. In September 2017, the EPA signed a rule to postpone the earliest compliance dates for certain waste streams regulations in the final ELG Rule from November 2018 to November 2020; however, the latest date for compliance for these regulations was December 2023. In October 2020, the EPA released the final rule that extended the latest dates for compliance with individual facilities’ compliance dates that would vary based on circumstances and the determination by state regulators and may range from 2021 to 2028. In May 2024, the EPA released a final rule revising the 2015 and 2020 Effluent Limitations Guidelines, establishing more stringent standards for wastewater discharges for the Steam Electric Power Generating Category, which apply primarily to wastewater discharges at coal and oil steam generating stations. Individual facilities’ compliance dates will vary based on circumstances and the determination by state regulators and may range to 2029, except in certain circumstances when a facility will be retired by 2034. DESC expects to complete wastewater treatment technology retrofits and modifications at the Williams generating station, with a similar project at the Wateree generation station under evaluation, to meet the requirements with the existing regulatory framework in South Carolina providing rate recovery mechanisms for costs of the projects. As discussed below, DESC recorded an increase to its AROs in the second quarter of 2024 in connection with the expected compliance costs associated with the EPA’s May 2024 final rule concerning CCR. DESC expects that such AROs would satisfy any AROs that would have otherwise been necessary for compliance with the EPA’s May 2024 Effluent Limitations Guidelines. DESC is currently unable to estimate what costs, if any, may be required in addition to the project for the Williams generating station, a potential project at the Wateree generating station and the recorded AROs to meet the requirements to operate certain facilities past 2034. However, DESC expects that while such costs for facility improvements, if required, could be material to its financial condition and/or cash flows, the existing regulatory framework in South Carolina provides rate recovery mechanisms that could substantially mitigate any such impacts.

Capacity Use Area

In November 2019, a new CUA was established in the counties surrounding the Cope Generating Station (Western Capacity Use Area) under the South Carolina Groundwater Use and Reporting Regulation. Under the regulation any groundwater well in a CUA that withdraws above three million gallons per month must be permitted. The Cope Generating Station is located within this new Western Capacity Use Area. Cope has been using four deep groundwater wells for cooling water and other house loads since 1996. Prior to designation of the new Western Capacity Use Area, the wells at Cope Station were only required to be registered not permitted. As a result of this designation, Cope will need to restore the surface water equipment to operable status to reduce reliance on groundwater wells. This includes completion of 316(b) requirements, (including SCDES BAT determination and modification of the station national pollutant discharge elimination system permit, which was obtained) and extensive inspection, repair and/or replacement of the associated surface water withdrawal equipment which has been idle since 1996. While the impacts of this rule

change are potentially material to DESC’s results of operations, financial condition and/or cash flows, the existing regulatory framework in South Carolina provides rate recovery mechanisms that could substantially mitigate any such impacts for DESC.

 

Waste Management and Remediation

The operations of DESC are subject to a variety of state and federal laws and regulations governing the management and disposal of solid and hazardous waste, and release of hazardous substances associated with current and/or historical operations. The CERCLA, as amended, and similar state laws, may impose joint, several and strict liability for cleanup on potentially responsible parties who owned, operated or arranged for disposal at facilities affected by a release of hazardous substances. In addition, many states have created programs to incentivize voluntary remediation of sites where historical releases of hazardous substances are identified and property owners or responsible parties decide to initiate cleanups.

 

From time to time, DESC may be identified as a potentially responsible party in connection with the alleged release of hazardous substances or wastes at a site. Under applicable federal and state laws, DESC could be responsible for costs associated with the investigation or remediation of impacted sites, or subject to contribution claims by other responsible parties for their costs incurred at such sites. DESC also may identify, evaluate and remediate other potentially impacted sites under voluntary state programs. Remediation costs may be subject to reimbursement under DESC’s insurance policies, rate recovery mechanisms, or both. Except as described below, DESC does not believe these matters will have a material effect on results of operations, financial condition and/or cash flows.

 

DESC has four decommissioned manufactured gas plant sites in South Carolina that are in various states of investigation, remediation and monitoring under work plans approved by, or under review by, the SCDES or the EPA. In the fourth quarter of 2023, DESC completed the majority of remediation activities at one site. DESC anticipates the remaining activities at that site will be completed by 2025 at an estimated cost of less than $1 million, after which the site will continue to incur ongoing maintenance and monitoring obligations. DESC expects to recover costs arising from the remediation work at all four sites through rate recovery mechanisms and as of December 31, 2024, deferred amounts, net of amounts previously recovered through rates and insurance settlements, totaled $33 million and are included in regulatory assets.

Ash Pond and Landfill Closure Costs

In April 2015, the EPA enacted a final rule regulating CCR landfills, existing ash ponds that still receive and manage CCRs, and inactive ash ponds that do not receive, but still store, CCRs. DESC currently has inactive and existing CCR ponds and CCR landfills subject to the final rule at three different facilities. This rule created a legal obligation for DESC to retrofit or close all of its inactive and existing ash ponds over a certain period of time, as well as perform required monitoring, corrective action, and post-closure care activities as necessary.

 

In December 2016, legislation was enacted that creates a framework for EPA-approved state CCR permit programs. In August 2017, the EPA issued interim guidance outlining the framework for state CCR program approval. The EPA has enforcement authority until state programs are approved. The EPA and states with approved programs both will have authority to enforce CCR requirements under their respective rules and programs. In September 2017, the EPA agreed to reconsider portions of the CCR rule in response to two petitions for reconsideration. In March 2018, the EPA proposed certain changes to the CCR rule related to issues remanded as part of the pending litigation and other issues the EPA is reconsidering. Several of the proposed changes would allow states with approved CCR permit programs additional flexibility in implementing their programs. In July 2018, the EPA promulgated the first phase of changes to the CCR rule. In August 2018, the U.S. Court of Appeals for the D.C. Circuit issued its decision in the pending challenges of the CCR rule, vacating and remanding to the EPA three provisions of the rule. In May 2024, the EPA released a final rule to regulate inactive surface impoundments located at retired generating stations that contained CCR and liquids after October 2015, and certain other inactive or previously closed surface impoundments, landfills or other areas that contain accumulations of CCR. DESC believes that it may have inactive or closed units or areas that could be subject to the final rule at up to seven different stations. In connection with this rule, in the second quarter of 2024, DESC recorded an increase to its AROs of $655 million, with a corresponding increase of $353 million to property, plant and equipment for amounts recoverable for electric generation stations that are currently in service and $302 million to regulatory assets for amounts recoverable through retail electric rates for electric generation stations that have been retired. In the third quarter of 2024, DESC recorded an adjustment to decrease the ARO and related property, plant and equipment by $215 million to reflect updated information concerning one facility. The actual AROs related to CCRs may vary substantially from the estimates used to record the obligation.

Claims and Litigation

The following describes certain legal proceedings involving DESC relating primarily to events occurring before closing of the SCANA Combination.

Matters Fully Resolved Prior to 2024 Impacting the Consolidated Financial Statements

 

Governmental Proceedings and Investigations

In June 2018, DESC received a notice of proposed assessment of approximately $410 million, excluding interest, from the SCDOR following its audit of DESC’s sales and use tax returns for the periods September 1, 2008 through December 31, 2017. The proposed assessment, which includes 100% of the NND Project, is based on the SCDOR’s position that DESC’s sales and use tax exemption for the NND Project does not apply because the facility will not become operational. In December 2020, the parties reached an agreement in principle in the amount of $165 million to resolve this matter. In June 2021, the parties executed a settlement agreement which allows DESC to fund the settlement amount through a combination of cash, shares of Dominion Energy common stock or real estate with an initial payment of at least $43 million in shares of Dominion Energy common stock. In August 2021, Dominion Energy issued 0.6 million shares of its common stock to satisfy DESC’s obligation for the initial payment under the settlement agreement. In May 2022, Dominion Energy issued an additional 0.9 million shares of its common stock to partially satisfy DESC’s remaining obligation under the settlement agreement. In June 2022, DESC requested approval from the South Carolina Commission to transfer certain real estate with a total settlement value of $51 million to satisfy its remaining obligation under the settlement agreement. In July 2022, the South Carolina Commission voted to approve the request and issued its final order in August 2022. In September 2022, DESC transferred certain non-utility property with a fair value of $28 million to the SCDOR under the settlement agreement, resulting in a gain of $19 million ($14 million after-tax) recorded in other income (expense), net in DESC’s Consolidated Statements of Comprehensive Income for the year ended December 31, 2022. In December 2022, DESC transferred additional utility property with a fair value of $3 million to the SCDOR, resulting in an inconsequential gain. In October 2022, DESC filed for approval to transfer the remaining real estate with FERC which was received in November 2022. In March 2023, DESC transferred utility property with a fair value of $10 million to the SCDOR resulting in a gain of $9 million ($7 million after-tax), recorded in other income (expense), net (reflected in the Corporate and Other segment) in DESC’s Consolidated Statements of Comprehensive Income for the year ended December 31, 2023. In June 2023, DESC transferred the remaining utility property with a fair value of $11 million to the SCDOR resulting in a gain of $11 million ($8 million after-tax), recorded in other income (expense), net (reflected in the Corporate and Other segment) in DESC’s Consolidated Statements of Comprehensive Income for the year ended December 31, 2023. In July 2023, DESC made a less than $1 million cash payment to the SCDOR to fully satisfy its remaining obligation, including applicable interest, under the settlement agreement.

 

SCANA Shareholder Litigation

In February 2018, a purported class action was filed against Dominion Energy and certain former directors of SCANA and DESC in the State Court of Common Pleas in Richland County, South Carolina (the Metzler Lawsuit). The plaintiff alleges, among other things, that defendants violated their fiduciary duties to shareholders by executing a merger agreement that would unfairly deprive plaintiffs of the true value of their SCANA stock, and that Dominion Energy aided and abetted these actions. Among other remedies, the plaintiff seeks to enjoin and/or rescind the merger. In February 2018, Dominion Energy removed the case to the U.S. District Court for the District of South Carolina and filed a Motion to Dismiss in March 2018. In September 2019, the U.S. District Court for the District of South Carolina granted the plaintiffs’ motion to consolidate the Metzler Lawsuit with another lawsuit regarding the SCANA Merger Agreement to which DESC is not a party. In October 2019, the plaintiffs filed an amended complaint against certain former directors and executive officers of SCANA and DESC, which stated substantially similar allegations to those in the initial lawsuits as well as an inseparable fraud claim. In November 2019, the defendants filed a motion to dismiss. In April 2020, the U.S. District Court for the District of South Carolina denied the motion to dismiss. In May 2020, SCANA filed a motion to intervene, which was denied in August 2020. In September 2020, SCANA filed a notice of appeal with the U.S. Court of Appeals for the Fourth Circuit. In June 2021, the parties reached an agreement in principle to settle this case, along with a related case to which DESC was not a party, subject to court approval, with no financial impact to DESC. In June 2022, this case was dismissed in connection with court approval of the related case to which DESC was not a party.

Nuclear Insurance

Under Price-Anderson, DESC (for itself and on behalf of Santee-Cooper) maintains agreements of indemnity with the U.S. Nuclear Regulatory Commission that, together with private insurance, cover third-party liability arising from any nuclear incident occurring at Summer. Price-Anderson provides funds up to $16.3 billion for public liability claims that could arise from a single nuclear incident. Each nuclear plant is insured against this liability to a maximum of $450 million by American Nuclear Insurers with the remaining coverage provided by a mandatory program of deferred premiums that could be assessed, after a nuclear incident, against all owners of commercial nuclear reactors. Each reactor licensee is liable for up to $166 million per reactor owned for each nuclear incident occurring at any reactor in the U.S., provided that not more than $25 million of the liability per reactor would be assessed per year. DESC’s maximum assessment, based on its two-thirds ownership of Summer, would be $111 million per incident, but not more than $9 million per year. Both the maximum assessment per reactor and the maximum yearly assessment are adjusted for inflation at least every five years.

During the first quarter of 2024, the total liability protection per nuclear incident available to all participants in the Secondary Financial Protection Program increased from $16.2 billion to $16.3 billion. This increase does not impact DESC’s responsibility per

active unit under the Price-Anderson Amendments Act of 1988. Additionally, Dominion Energy increased the amount of coverage purchased from commercial insurance pools for Summer from $450 million to $500 million with the remainder provided through the mandatory industry retrospective rating plan.

 

DESC currently maintains insurance policies (for itself and on behalf of Santee Cooper) with NEIL. The policies provide coverage to Summer for property damage and outage costs up to $1.06 billion resulting from an event of nuclear origin and up to $1 million resulting from an event of a non-nuclear origin. The NEIL policies in aggregate, are subject to a maximum loss of $1.06 billion for any single loss occurrence. The NEIL policies permit retrospective assessments under certain conditions to cover insurer’s losses. Based on the current annual premium, DESC’s portion of the retrospective premium assessment would not exceed $7 million. DESC currently maintains an excess property insurance policy (for itself and on behalf of Santee Cooper) with EMANI. The policy provides coverage to Summer for property damage and outage costs up to $1 million resulting from an event of a non-nuclear origin. The EMANI policy permits retrospective assessments under certain conditions to cover insurer’s losses. Based on the current annual premium, DESC’s portion of the retrospective premium assessment would not exceed an inconsequential amount.

 

To the extent that insurable claims for property damage, decontamination, repair and replacement and other costs and expenses arising from an incident at Summer exceed the policy limits of insurance, or to the extent such insurance becomes unavailable in the future, and to the extent that DESC’s rates would not recover the cost of any purchased replacement power, DESC will retain the risk of loss as a self-insurer. DESC has no reason to anticipate a serious nuclear or other incident. However, if such an incident were to occur, it likely would have a material impact on DESC’s results of operations, cash flows and financial position.

 

Spent Nuclear Fuel

The Nuclear Waste Policy Act of 1982 required that the United States government accept and permanently dispose of high-level radioactive waste and spent nuclear fuel by January 31, 1998, and it imposed on utilities the primary responsibility for storage of their spent nuclear fuel until the repository is available. DESC entered into a Standard Contract for Disposal of Spent Nuclear Fuel and/or High-Level Radioactive Waste with the DOE in 1983. By mutual agreement of the parties, damage award payments and settlement payments are made until the DOE has accepted the same amount of spent fuel from the facility as if it has fully performed its contractual obligations. In 2024, DESC received payment of $2 million for resolution of its share of claims incurred at Summer for the period of January 1, 2023 through December 31, 2023. In 2023, DESC received payment of $6 million for resolution of its share of claims incurred at Summer for the period of January 1, 2022 through December 31, 2022. In 2022, DESC received payment of $1 million for resolution of its share of claims incurred at Summer for the period of January 1, 2021 through December 31, 2021. As of December 31, 2024, the federal government has not accepted any spent fuel from Summer, and it remains unclear when the repository may become available. DESC has constructed an independent spent fuel storage installation to accommodate the spent nuclear fuel output for the life of Summer. DESC may evaluate other technology as it becomes available.

 

Long-Term Purchase Agreements

At December 31, 2024, DESC had the following long-term commitments that are noncancelable or cancelable only under certain conditions, and that a third party that will provide the contracted goods or services has used to secure financing.

 

 

2025

 

 

2026

 

 

2027

 

 

2028

 

 

2029

 

 

Thereafter

 

 

Total

 

Purchased electric capacity(1)(2)

 

$

85

 

 

$

88

 

 

$

89

 

 

$

88

 

 

$

87

 

 

$

473

 

 

$

910

 

 

(1)
Includes affiliated amounts with certain solar facilities of $173 million.
(2)
Commitments represent estimated amounts payable for energy under power purchase contracts with qualifying facilities which expire at various dates through 2040. Energy payments are generally based on fixed dollar amounts per month and totaled $70 million in 2024, $70 million in 2023 and $75 million in 2022.

Surety Bonds

At December 31, 2024, DESC had purchased $24 million of surety bonds. Under the terms of surety bonds, DESC is obligated to indemnify the respective surety bond company for any amounts paid.

v3.25.0.1
Leases
 12 Months Ended
Dec. 31, 2024
Leases [Abstract]  
Leases

13. LEASES

At December 31, 2024 and 2023, DESC had the following lease assets and liabilities recorded in the Consolidated Balance Sheets:

 

At December 31,

 

2024

 

 

2023

 

(millions)

 

 

 

 

 

 

Lease assets:

 

 

 

 

 

 

Operating lease assets(1)

 

$

20

 

 

$

18

 

Finance lease assets(2)

 

 

3

 

 

 

6

 

Total lease assets

 

$

23

 

 

$

24

 

Lease liabilities:

 

 

 

 

 

 

Operating lease - current(3)

 

$

3

 

 

$

2

 

Operating lease - noncurrent(4)

 

 

18

 

 

 

17

 

Finance lease - current(5)

 

 

2

 

 

 

3

 

Finance lease - noncurrent

 

 

2

 

 

 

4

 

Total lease liabilities

 

$

25

 

 

$

26

 

 

(1)
Included in other deferred debits and other assets in the Consolidated Balance Sheets.
(2)
Included in utility plant, net, in the Consolidated Balance Sheets, net of $15 million and $17 million of accumulated amortization at December 31, 2024 and December 31, 2023, respectively.
(3)
Included in other current liabilities in the Consolidated Balance Sheets.
(4)
Included in other deferred credits and other liabilities in the Consolidated Balance Sheets.
(5)
Included in securities due within one year in the Consolidated Balance Sheets.

For the years ended December 31, 2024, 2023 and 2022, total lease cost consisted of the following:

 

Year Ended December 31,

 

2024

 

 

2023

 

 

2022

 

(millions)

 

 

 

 

 

 

 

 

 

Finance lease cost:

 

 

 

 

 

 

 

 

 

Amortization

 

$

3

 

 

$

3

 

 

$

4

 

Interest

 

 

—

 

 

 

—

 

 

 

1

 

Operating lease cost

 

 

4

 

 

 

5

 

 

 

4

 

Short-term lease cost

 

 

1

 

 

 

2

 

 

 

2

 

Total lease cost

 

$

8

 

 

$

10

 

 

$

11

 

 

For the years ended December 31, 2024, 2023 and 2022, cash paid for amounts included in the measurement of lease liabilities consisted of the following amounts, included in the Consolidated Statements of Cash Flows:

 

Year Ended December 31,

 

2024

 

 

2023

 

 

2022

 

(millions)

 

 

 

 

 

 

 

 

 

Operating cash flows from finance leases

 

$

—

 

 

$

—

 

 

$

1

 

Operating cash flows from operating leases

 

 

4

 

 

 

4

 

 

 

6

 

Financing cash flows from finance leases

 

 

3

 

 

 

4

 

 

 

4

 

 

At December 31, 2024 and 2023, the weighted-average remaining lease term and weighted-average discount rate for finance and operating leases were as follows:

 

At December 31,

 

2024

 

 

2023

 

Weighted-average remaining lease term - finance leases

 

3 years

 

 

3 years

 

Weighted-average remaining lease term - operating leases

 

16 years

 

 

18 years

 

Weighted-average discount rate - finance leases

 

 

3.17

%

 

 

2.96

%

Weighted-average discount rate - operating leases

 

 

4.34

%

 

 

4.12

%

 

 

Lease liabilities have the following scheduled maturities:

 

(millions)

 

Operating

 

 

Finance

 

2025

 

$

3

 

 

$

2

 

2026

 

 

3

 

 

 

1

 

2027

 

 

2

 

 

 

1

 

2028

 

 

2

 

 

 

—

 

2029

 

 

2

 

 

 

—

 

After 2029

 

 

20

 

 

 

—

 

Total undiscounted lease payments

 

 

32

 

 

 

4

 

Present value adjustment

 

 

(11

)

 

 

—

 

Present value of lease liabilities

 

$

21

 

 

$

4

 
v3.25.0.1
Operating Segments
 12 Months Ended
Dec. 31, 2024
Segment Reporting [Abstract]  
Operating Segments

14. OPERATING SEGMENTS

The Corporate and Other Segment primarily includes specific items attributable to DESC’s operating segment that are not included in profit measures evaluated by executive management in assessing the segment’s performance or in allocating resources.

 

DESC’s CODM for the year ended December 31, 2024 was the CEO. The CODM uses net income (loss) as the primary profit or loss measure at each segment. The CODM considers budget-to-actual variances on a quarterly basis when making decisions about allocating operating and capital resources to each segment, when assessing the performance of each segment and when determining the compensation of certain employees.

 

In 2024, DESC reported after-tax net expenses of $47 million for specific items in the Corporate and Other segment, all of which was attributable to its operating segment.

 

The net expense for specific items attributable to DESC’s operating segment in 2024 primarily related to a $58 million ($44 million after-tax) charge in connection with the electric base rate case.

 

In 2023, DESC reported after-tax net income of $18 million for specific items in the Corporate and Other segment, all of which was attributable to its operating segment.

 

The net income for specific items attributable to DESC’s operating segment in 2023 primarily related to a $28 million ($21 million after-tax) benefit related to real estate transactions, including gains on the transfer of property to satisfy litigation associated with the NND Project.

 

In 2022, DESC reported after-tax expenses of $3 million for specific items in the Corporate and Other segment, all of which was attributable to its operating segment.

 

The following table presents segment information pertaining to DESC’s operations:

Year Ended December 31,

 

Dominion Energy
South Carolina

 

 

Corporate
and Other

 

 

Consolidated
Total

 

(millions)

 

 

 

 

 

 

 

 

 

2024

 

 

 

 

 

 

 

 

 

Operating Revenue

 

$

3,173

 

 

$

—

 

 

$

3,173

 

Fuel used in electric generation(1)

 

 

603

 

 

 

—

 

 

 

603

 

Purchased power(1)

 

 

68

 

 

 

—

 

 

 

68

 

Gas purchased for resale(1)

 

 

245

 

 

 

—

 

 

 

245

 

Other operations and maintenance(1)(2)

 

 

658

 

 

 

59

 

 

 

717

 

Depreciation and amortization(1)

 

 

546

 

 

 

—

 

 

 

546

 

Other taxes(1)

 

 

300

 

 

 

—

 

 

 

300

 

Total Operating Expenses

 

 

2,420

 

 

 

59

 

 

 

2,479

 

Other income, net(3)

 

 

2

 

 

 

(3

)

 

 

(1

)

Interest charges, net of AFUDC(1)

 

 

276

 

 

 

—

 

 

 

276

 

Income tax expense (benefit)(1)

 

 

80

 

 

 

(15

)

 

 

65

 

Deferred cost of employee benefit plans, net of tax(3)

 

 

—

 

 

 

—

 

 

 

—

 

Comprehensive Income Attributable to Noncontrolling Interest(3)

 

 

23

 

 

 

—

 

 

 

23

 

Comprehensive Income (Loss) Available (Attributable) to
   Common Shareholder

 

 

376

 

 

 

(47

)

 

 

329

 

Capital expenditures

 

 

1,105

 

 

 

—

 

 

 

1,105

 

Total assets (billions)

 

 

17.0

 

 

 

—

 

 

 

17.0

 

 

 

 

 

 

 

 

 

 

2023

 

 

 

 

 

 

 

 

 

Operating Revenue

 

$

3,028

 

 

$

—

 

 

$

3,028

 

Fuel used in electric generation(1)

 

 

582

 

 

 

—

 

 

 

582

 

Purchased power(1)

 

 

72

 

 

 

—

 

 

 

72

 

Gas purchased for resale(1)

 

 

243

 

 

 

—

 

 

 

243

 

Other operations and maintenance(1)(2)

 

 

626

 

 

 

(24

)

 

 

602

 

Depreciation and amortization(1)

 

 

531

 

 

 

—

 

 

 

531

 

Other taxes(1)

 

 

292

 

 

 

—

 

 

 

292

 

Total Operating Expenses

 

 

2,346

 

 

 

(24

)

 

 

2,322

 

Other income, net(3)

 

 

24

 

 

 

—

 

 

 

24

 

Interest charges, net of AFUDC(1)

 

 

250

 

 

 

—

 

 

 

250

 

Income tax expense(1)

 

 

79

 

 

 

6

 

 

 

85

 

Deferred cost of employee benefit plans, net of tax(3)

 

 

1

 

 

 

—

 

 

 

1

 

Comprehensive Income Attributable to Noncontrolling Interest(3)

 

 

21

 

 

 

—

 

 

 

21

 

Comprehensive Income Available to Common Shareholder

 

 

357

 

 

 

18

 

 

 

375

 

Capital expenditures

 

 

957

 

 

 

—

 

 

 

957

 

Total assets (billions)

 

 

15.9

 

 

 

—

 

 

 

15.9

 

 

 

 

 

 

 

 

 

 

2022

 

 

 

 

 

 

 

 

 

Operating Revenue

 

$

3,783

 

 

$

—

 

 

$

3,783

 

Fuel used in electric generation(1)

 

 

1,000

 

 

 

—

 

 

 

1,000

 

Purchased power(1)

 

 

137

 

 

 

—

 

 

 

137

 

Gas purchased for resale(1)

 

 

433

 

 

 

—

 

 

 

433

 

Other operations and maintenance(1)(2)

 

 

626

 

 

 

4

 

 

 

630

 

Depreciation and amortization(1)

 

 

507

 

 

 

—

 

 

 

507

 

Other taxes(1)

 

 

277

 

 

 

—

 

 

 

277

 

Total Operating Expenses

 

 

2,980

 

 

 

4

 

 

 

2,984

 

Other income, net(3)

 

 

55

 

 

 

—

 

 

 

55

 

Interest charges, net of AFUDC(1)

 

 

220

 

 

 

—

 

 

 

220

 

Income tax expense (benefit)(1)

 

 

132

 

 

 

(1

)

 

 

131

 

Deferred cost of employee benefit plans, net of tax(3)

 

 

(1

)

 

 

—

 

 

 

(1

)

Comprehensive Income Attributable to Noncontrolling Interest(3)

 

 

20

 

 

 

—

 

 

 

20

 

Comprehensive Income (Loss) Available (Attributable) to
   Common Shareholder

 

 

485

 

 

 

(3

)

 

 

482

 

Capital expenditures

 

 

697

 

 

 

—

 

 

 

697

 

 

(1)
The significant expense categories and amounts in the segment information presented above align with the segment-level information that is regularly provided to DESC’s CODM.
(2)
Includes impairment of assets and other charges.
(3)
Items designated are other segment items for each reportable segment.
v3.25.0.1
Utility Plant and Nonutility Property
 12 Months Ended
Dec. 31, 2024
Utility Plant And Non Utility Property [Abstract]  
Utility Plant and Nonutility Property

15. UTILITY PLANT AND NONUTILITY PROPERTY

Major classes of utility plant and other property and their respective balances at December 31, 2024 and 2023 were as follows:

 

At December 31,

 

2024

 

 

2023

 

(millions)

 

 

 

 

 

 

Gross utility plant:

 

 

 

 

 

 

Generation

 

$

6,635

 

 

$

6,322

 

Transmission

 

 

2,342

 

 

 

2,272

 

Distribution

 

 

6,311

 

 

 

5,901

 

Storage

 

 

79

 

 

 

79

 

General and other

 

 

651

 

 

 

644

 

Intangible

 

 

282

 

 

 

282

 

Construction work in progress

 

 

899

 

 

 

606

 

Nuclear fuel

 

 

570

 

 

 

609

 

Total gross utility plant

 

$

17,769

 

 

$

16,715

 

Gross nonutility property

 

$

16

 

 

$

25

 

Jointly Owned Utility Plant

DESC jointly owns and is the operator of Summer. Each joint owner provides its own financing and shares the direct expenses and generation output in proportion to its ownership. DESC’s share of the direct expenses of Summer is included in the corresponding operating expenses on its income statement. The units associated with the NND Project, net of impairment charges, have been reclassified from construction work in progress to a regulatory asset as a result of the decision to stop their construction. See additional discussion at Note 3.

 

At December 31,

 

2024

 

2023

 

 

Summer Unit 1

 

Summer Unit 1

Percent owned

 

66.7%

 

66.7%

Plant in service

 

$

1.6

 

billion

 

$

1.6

 

billion

Accumulated depreciation

 

$

784

 

million

 

$

772

 

million

Construction work in progress

 

$

58

 

million

 

$

88

 

million

 

Included within other receivables on the balance sheet were amounts due to DESC from Santee Cooper for its share of direct expenses. These amounts totaled $36 million at December 31, 2024 and $50 million at December 31, 2023.
v3.25.0.1
Affiliated and Related Party Transactions
 12 Months Ended
Dec. 31, 2024
Related Party Transactions [Abstract]  
Affiliated and Related Party Transactions

16. AFFILIATED AND RELATED PARTY TRANSACTIONS

DES, on behalf of itself and its parent company, provides the following services to DESC, which are rendered at direct or allocated cost: information systems, telecommunications, customer support, marketing and sales, human resources, corporate compliance, purchasing, financial, risk management, public affairs, legal, investor relations, gas supply and capacity management, strategic planning, general administrative and retirement benefits. Costs for these services include amounts capitalized. Amounts expensed are primarily recorded in other operations and maintenance - affiliated suppliers and other income, net in the Consolidated Statements of Comprehensive Income.

DESC transacts with affiliates for certain quantities of electricity in the ordinary course of business. DESC also enters into certain commodity derivative contracts with affiliates. DESC uses these contracts, which are principally comprised of forward commodity purchases, to manage commodity price risks associated with purchases of electricity. See Note 8 for more information.

 

Year Ended December 31,

 

2024

 

 

2023

 

 

2022

 

(millions)

 

 

 

 

 

 

 

 

 

Direct and allocated costs from DES(1)

 

$

222

 

 

$

222

 

 

$

212

 

Operating Revenues – Electric from sales to affiliate

 

 

7

 

 

 

4

 

 

 

4

 

Operating Revenues – Gas from sales to affiliate

 

 

1

 

 

 

1

 

 

 

1

 

Operating Expenses – Other taxes from affiliate

 

 

8

 

 

 

8

 

 

 

8

 

Purchases of electricity from solar affiliates

 

 

8

 

 

 

13

 

 

 

14

 

 

(1)
Includes capitalized expenditures of $57 million, $59 million and $48 million for the years ended December 31, 2024, 2023 and 2022, respectively.

 

At December 31,

 

2024

 

 

2023

 

(millions)

 

 

 

 

 

 

Payable to DES

 

 

19

 

 

 

18

 

Payable to SCANA Corporation

 

 

7

 

 

 

7

 

Payable to PSNC

 

 

 

 

 

13

 

Derivative assets with affiliates(1)

 

 

48

 

 

 

33

 

 

(1)
Includes amounts recorded in current derivative assets of $4 million and $2 million as of December 31, 2024 and 2023, respectively, and amounts recorded in noncurrent derivative assets of $44 million and $31 million as of December 31, 2024 and 2023, respectively.

 

Certain disclosures regarding tax related affiliate balances are included in Note 2. Borrowings from an affiliate are described in Note 6. Certain disclosures regarding DESC’s participation in SCANA’s noncontributory defined benefit pension plan and unfunded postretirement health care and life insurance programs are included in Note 11.
v3.25.0.1
Other Income (Expense), Net
 12 Months Ended
Dec. 31, 2024
Income Statement [Abstract]  
Other Income (Expense), Net

17. OTHER INCOME (EXPENSE), NET

Components of other income (expense), net are as follows:

 

Year Ended December 31,

 

2024

 

 

2023

 

 

2022

 

(millions)

 

 

 

 

 

 

 

 

 

Other income

 

$

12

 

 

$

8

 

 

$

10

 

Gains on sales of assets(1)

 

 

4

 

 

 

32

 

 

 

42

 

Other expense

 

 

(19

)

 

 

(16

)

 

 

2

 

Allowance for equity funds used during construction

 

 

2

 

 

 

—

 

 

 

1

 

Other income (expense), net

 

$

(1

)

 

$

24

 

 

$

55

 
(1)
Includes amounts recognized in connection with the transfer of property, plant and equipment to satisfy litigation in 2023 and 2022. See Note 12 for additional information.

Non-service cost components of pension and other postretirement benefits are included in other expense.

 

In 2023, DESC completed the sale of certain utility property in South Carolina, as approved by the South Carolina Commission in February 2023, for total cash consideration of $12 million. In connection with the sale, DESC recognized a net gain of $11 million ($8 million after-tax), reflected in the Corporate and Other segment, for the year ended December 31, 2023.

 

In 2022, DESC completed the sales of certain utility property in South Carolina, as approved by the South Carolina Commission, for total cash consideration of $20 million. In connection with the sales, DESC recognized a gain of $20 million ($15 million after-tax) for the year ended December 31, 2022.
v3.25.0.1
Summary of Significant Accounting Policies (Policies)
 12 Months Ended
Dec. 31, 2024
Accounting Policies [Abstract]  
General

General

DESC makes certain estimates and assumptions in preparing its Consolidated Financial Statements in accordance with GAAP. These estimates and assumptions affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the dates of the financial statements and the reported amounts of revenues, expenses and cash flows for the periods presented. Actual results may differ from those estimates.

DESC’s Consolidated Financial Statements include, after eliminating intercompany balances and transactions, the accounts of DESC, GENCO and Fuel Company. DESC has concluded that GENCO and Fuel Company are VIEs due to the members lacking the characteristics of a controlling financial interest. DESC is the primary beneficiary of GENCO and Fuel Company and therefore is required to consolidate the VIEs. The equity interests in GENCO and Fuel Company are held solely by SCANA, DESC’s parent. As a result, GENCO and Fuel Company’s equity and results of operations are reflected as noncontrolling interest in the Consolidated Financial Statements.

GENCO owns a coal-fired electric generating station with a 605 MW net generating capacity (summer rating). GENCO’s electricity is sold exclusively to DESC, pursuant to a FERC approved power purchase agreement and related operating agreement. The effects of these transactions are eliminated in consolidation. Fuel Company acquires, owns and provides financing for DESC’s nuclear fuel, certain fossil fuels and emission and other environmental allowances. See also Note 6.

Additionally, DESC purchases shared services from DES, an affiliated VIE that provides accounting, legal, finance and certain administrative and technical services to all Dominion Energy subsidiaries, including DESC. DESC has determined that it is not the primary beneficiary of DES as it does not have either the power to direct the activities that most significantly impact its economic performance or an obligation to absorb losses and benefits which could be significant to it. See Note 16 for amounts attributable to affiliates.

DESC reports certain contracts and instruments at fair value. See below and Note 9 for further information on fair value measurements.

DESC maintains pension and other postretirement benefit plans. See Note 11 for further information on these plans.

Certain amounts in the 2023 and 2022 Consolidated Financial Statements and Notes have been reclassified to conform to the 2024 presentation for comparative purposes; however, such reclassifications did not affect DESC’s net income, total assets, liabilities, equity or cash flows.

Utility Plant

Utility Plant

Utility plant is stated at original cost. The costs of additions, replacements and betterments to utility plant, including direct labor, material and indirect charges for engineering, supervision and AFUDC, are added to utility plant accounts. The original cost of utility property retired or otherwise disposed of is removed from utility plant accounts and generally charged to accumulated depreciation. Cost of removal collections from utility customers are recorded as regulatory liabilities. The costs of repairs and replacements of items of property determined to be less than a unit of property or that do not increase the asset’s life or functionality are charged to expense.

AFUDC is a noncash item that reflects the period cost of capital devoted to plant under construction. This accounting practice results in the inclusion of, as a component of construction cost, the costs of debt and equity capital dedicated to construction investment. AFUDC is included in rate base investment and depreciated as a component of plant cost in establishing rates for utility services.

DESC calculated AFUDC using average composite rates of 5.3%, 5.3% and 2.7% for 2024, 2023 and 2022, respectively. These rates do not exceed the maximum rates allowed in the various regulatory jurisdictions. DESC capitalizes interest on nuclear fuel in process at the actual interest cost incurred.

For property subject to cost-of-service rate regulation that will be abandoned significantly before the end of its useful life, the net carrying value is reclassified from utility plant-in-service when it becomes probable it will be abandoned and recorded as a regulatory asset for amounts expected to be collected through future rates.

Provisions for depreciation and amortization are recorded using the straight-line method based on the estimated service lives of the various classes of property, and in most cases, include provisions for future cost of removal. The composite weighted-average depreciation rates for utility plant by function were as follows:

Year Ended December 31,

 

2024

 

 

2023

 

 

2022

 

(percent)

 

 

 

 

 

 

 

 

 

Generation

 

 

2.33

 

 

 

2.33

 

 

 

2.34

 

Transmission

 

 

2.53

 

 

 

2.54

 

 

 

2.36

 

Distribution

 

 

2.53

 

 

 

2.57

 

 

 

2.59

 

Storage

 

 

2.75

 

 

 

2.83

 

 

 

2.93

 

General and other

 

 

3.15

 

 

 

3.16

 

 

 

3.35

 

DESC records nuclear fuel amortization using the units-of-production method, which is included in fuel used in electric generation and recovered through the fuel cost component of retail electric rates.
Major Maintenance

Major Maintenance

Planned major maintenance costs related to certain fossil fuel turbine generator equipment, nuclear refueling outages and cyclical tree trimming and vegetation management are collected in rates and accrued in periods other than when incurred in accordance with approval by the South Carolina Commission for such accounting treatment and rate recovery of expenses accrued thereunder. The difference between such cumulative major maintenance costs and cumulative collections is classified as a regulatory asset or regulatory liability on the consolidated balance sheet. Other planned major maintenance is expensed when incurred.

DESC is authorized to collect $25 million annually through electric rates to offset certain turbine generator maintenance expenditures. For the years ended December 31, 2024, 2023 and 2022, DESC incurred $16 million, $20 million and $20 million, respectively, for turbine generator maintenance.

Nuclear refueling outages are scheduled 18 months apart. As approved by the South Carolina Commission, DESC accrued $17 million annually through August 2024 and $24 million annually beginning September 2024 for its portion of the nuclear refueling outages, that are scheduled to occur from the fall of 2024 through the fall of 2030 as well as unrecovered balances from the previous accrual cycle. Refueling outage costs incurred for which DESC was responsible totaled $42 million in 2024, $26 million in 2023 and $1 million in 2022.

Effective September 2021, DESC implemented a tree trimming and vegetation management accrual where costs associated with cyclical tree trimming and vegetation management are accrued over the five-year operating cycle DESC seeks to maintain for such activities. As approved by the South Carolina Commission, DESC accrued $28 million annually through August 2024 and $34 million annually beginning September 2024. During the years ended December 31, 2024, 2023 and 2022, DESC incurred costs totaling $29 million, $31 million and $33 million, respectively.

Asset Retirement Obligations

Asset Retirement Obligations

DESC recognizes AROs at fair value as incurred or when sufficient information becomes available to determine a reasonable estimate of the fair value of future retirement activities to be performed, for which a legal obligation exists. These amounts are generally capitalized as costs of the related tangible long-lived assets. Since relevant market information is not available, fair value is estimated using discounted cash flow analyses. Periodically, DESC assesses its AROs to determine if circumstances indicate that estimates of the amounts or timing of future cash flows associated with retirement activities have changed. AROs are adjusted when significant changes in the amounts or timing of future cash flows are identified. DESC reports accretion of AROs and depreciation on asset retirement costs as an adjustment to regulatory assets.

Nuclear Decommissioning

Nuclear Decommissioning

Based on a decommissioning cost study completed in 2020, DESC’s two-thirds share of estimated site-specific nuclear decommissioning costs for Summer, including the cost of decommissioning plant components both subject to and not subject to radioactive contamination, totals $831 million, stated in 2024 dollars. Santee Cooper is responsible for decommissioning costs related to its one-third ownership interest in Summer. The cost estimate assumes that the site will be maintained over a period of approximately 60 years in such a manner as to allow for subsequent decontamination that would permit release for unrestricted use.

Under DESC’s method of funding decommissioning costs, DESC transfers to an external trust fund the amounts collected through rates ($3 million in each period presented), less expenses. The trust invests the amounts transferred into insurance policies on the lives of certain company personnel. Insurance proceeds are reinvested in insurance policies. The asset balance held in trust reflects the net cash surrender value of the insurance policies and cash held by the trust. Management intends for the fund, including earnings thereon, to provide for all eventual decommissioning expenditures for Summer on an after-tax basis.
Cash, Restricted Cash and Equivalents

Cash, Restricted Cash and Equivalents

Cash, restricted cash and equivalents include cash on hand, cash in banks and temporary investments purchased with an original maturity of three months or less.

 

Restricted Cash and Equivalents

DESC may hold restricted cash and equivalent balances that consists of federal assistance funds to be used towards customer bill assistance.

 

The following table provides a reconciliation of the total cash, restricted cash and equivalents reported within DESC’s Consolidated Balance Sheets to the corresponding amounts reported within DESC’s Consolidated Statements of Cash Flows for the years ended December 31, 2024, 2023 and 2022:

 

 

 

Cash, Restricted Cash and Equivalents at End/Beginning of Year

 

 

 

December 31, 2024

 

 

December 31, 2023

 

 

December 31, 2022

 

 

December 31, 2021

 

(millions)

 

 

 

 

 

 

 

 

 

 

 

 

Cash and cash equivalents

 

$

—

 

 

$

1

 

 

$

11

 

 

$

30

 

Restricted cash and equivalents(1)

 

 

—

 

 

 

—

 

 

 

—

 

 

 

24

 

Cash, restricted cash and equivalents shown in the
   Consolidated Statements of Cash Flows

 

$

—

 

 

$

1

 

 

$

11

 

 

$

54

 
(1)
Restricted cash and equivalent balances are presented within other current assets on the Consolidated Balance Sheets.
Receivables

Receivables

Customer receivables reflect amounts due from customers arising from the delivery of energy or related services and include both billed and unbilled amounts earned pursuant to revenue recognition practices described in Note 4. Customer receivables are generally due within one month of receipt of invoices which are presented on a monthly cycle basis. Unbilled revenues totaled $176 million at both December 31, 2024 and 2023.

DESC sells electricity and natural gas and provides distribution and transmission services to customers in South Carolina. Management believes that this geographic concentration risk is mitigated by the diversity of DESC’s customer base, which includes a large number of residential, commercial and industrial customers. Credit risk associated with accounts receivable is limited due to the large number of customers. DESC’s exposure to potential concentrations of credit risk results primarily from amounts due from Santee Cooper related to the jointly owned nuclear generating facility at Summer. Such receivables represented approximately 7% of DESC’s accounts receivable balance at December 31, 2024.
Inventories

Inventories

Materials and supplies include the average cost of transmission, distribution and generating plant materials. Materials are charged to inventory when purchased and then expensed or capitalized to plant, as appropriate, at weighted-average cost when used. Fuel inventory includes the average cost of coal, natural gas, fuel oil and emission allowances. Fuel is charged to inventory when purchased and is expensed, at weighted-average cost, as used and recovered through fuel cost recovery rates approved by the South Carolina Commission.
Income Taxes

Income Taxes

A consolidated federal income tax return is filed for Dominion Energy and its subsidiaries, including DESC. In addition, where applicable, combined income tax returns for Dominion Energy, including DESC, are filed in various states including South Carolina; otherwise, separate state income tax returns are filed.

DESC participates in an intercompany tax sharing agreement with Dominion Energy. Current income taxes are based on taxable income or loss and credits determined on a separate company basis.

Under the agreements, if a subsidiary incurs a tax loss or earns a credit, recognition of current income tax benefits is limited to refunds of prior year taxes obtained by the carryback of the net operating loss or credit or to the extent the tax loss or credit is absorbed by the taxable income of other Dominion Energy consolidated group members. Otherwise, the net operating loss or credit is carried forward and is recognized as a deferred tax asset until realized.

Accounting for income taxes involves an asset and liability approach. Deferred income tax assets and liabilities are provided, representing future effects on income taxes for temporary differences between the bases of assets and liabilities for financial reporting and tax purposes. Accordingly, deferred taxes are recognized for the future consequences of different treatments used for the reporting of transactions in financial accounting and income tax returns. DESC establishes a valuation allowance when it is more-likely-than-not that all, or a portion, of a deferred tax asset will not be realized. DESC did not have any valuation allowances recorded for the periods presented. Where the treatment of temporary differences is different for rate-regulated operations, a regulatory asset is recognized if it is probable that future revenues will be provided for the payment of deferred tax liabilities.

DESC recognizes positions taken, or expected to be taken, in income tax returns that are more-likely-than-not to be realized, assuming that the position will be examined by tax authorities with full knowledge of all relevant information. At December 31, 2024 and 2023, DESC had $38 million and $62 million, respectively, of unrecognized tax benefits.

If it is not more-likely-than-not that a tax position, or some portion thereof, will be sustained, the related tax benefits are not recognized in the financial statements. Unrecognized tax benefits may result in an increase in income taxes payable, a reduction of income tax refunds receivable or changes in deferred taxes. Also, when uncertainty about the deductibility of an amount is limited to the timing of such deductibility, the increase in income taxes payable (or reduction in tax refunds receivable) is accompanied by a decrease in deferred tax liabilities. Except when such amounts are presented net with amounts receivable from or amounts prepaid to tax authorities, noncurrent income taxes payable related to unrecognized tax benefits are classified in other deferred credits and other liabilities on the Consolidated Balance Sheets and current payables are included in taxes accrued on the Consolidated Balance Sheets.

DESC recognizes interest on underpayments and overpayments of income taxes in interest expense and interest income, respectively. Penalties are also recognized in other expenses. DESC recorded interest expense of $12 million in 2024 with inconsequential amounts recorded in 2023 and 2022.

At December 31, 2024, DESC had an income tax-related affiliated payable of $12 million to Dominion Energy. This balance is expected to be paid to Dominion Energy in 2025.

At December 31, 2023, DESC had an income tax-related affiliated payable of $15 million to Dominion Energy. This balance was paid to Dominion Energy in 2024.

At DESC investment tax credits are deferred and amortized over the service lives of the properties giving rise to the credits. Production tax credits are recognized as energy is generated and sold.
Regulatory Assets and Liabilities

Regulatory Assets and Liabilities

The accounting for DESC’s regulated electric and gas operations differs from the accounting for nonregulated operations in that DESC is required to reflect the effect of rate regulation in its Consolidated Financial Statements. For regulated businesses subject to federal or state cost-of-service rate regulation, regulatory practices that assign costs to accounting periods may differ from accounting methods generally applied by nonregulated companies. When it is probable that regulators will permit the recovery of current costs through future rates charged to customers, these costs that otherwise would be expensed by nonregulated companies are deferred as regulatory assets. Likewise, regulatory liabilities are recognized when it is probable that regulators will require customer refunds or other benefits through future rates or when revenue is collected from customers for expenditures that have yet to be incurred.

 

DESC evaluates whether or not recovery of its regulatory assets through future rates is probable as well as whether a regulatory liability due to customers is probable and makes various assumptions in its analyses. These analyses are generally based on:

 

•
Orders issued by regulatory commissions, legislation and judicial actions;
•
Past experience; and
•
Discussions with applicable regulatory authorities and legal counsel.

Generally, regulatory assets and liabilities are amortized into income over the period authorized by the regulator. If recovery of a regulatory asset is determined to be less than probable, it will be written off in the period such assessment is made. A regulatory liability, if considered probable, will be recorded in the period such assessment is made or reversed into earnings if no longer probable. See Note 3 to the Consolidated Financial Statements for additional information.
Derivative Instruments

Derivative Instruments

DESC is exposed to the impact of market fluctuations in the price of electricity and natural gas it markets and purchases, as well as interest rate risk in its business operations. DESC uses derivative instruments such as physical forwards, options and swaps to manage commodity and/or interest rate risks of its business operations.

 

Derivative assets and liabilities are presented gross on DESC’s Consolidated Balance Sheets. Derivative contracts representing unrealized gain positions and purchased options are reported as derivative assets. Derivative contracts representing unrealized losses and options sold are reported as derivative liabilities. All derivatives, except those for which an exception applies, are required to be reported in the Consolidated Balance Sheets at fair value. One of the exceptions to fair value accounting, normal purchases and normal sales, may be elected when the contract satisfies certain criteria, including a requirement that physical delivery of the underlying commodity is probable. Contracts for the future purchase of certain quantities of natural gas that no longer meet the criteria for the normal purchase normal sale exception are accounted for as derivative contracts. Expenses and revenues resulting from deliveries under normal purchase contracts and normal sales contracts, respectively, are included in earnings at the time of contract performance. See Fair Value Measurements below for additional information about fair value measurements and associated valuation methods for derivatives.

 

DESC’s derivative contracts include over-the-counter transactions. Over-the-counter contracts are bilateral contracts that are transacted directly with a third party. Certain over-the-counter contracts contain contractual rights of setoff through master netting arrangements and contract default provisions. In addition, the contracts are subject to conditional rights of setoff through counterparty nonperformance, insolvency, or other conditions.

 

In general, most over-the-counter transactions are subject to collateral requirements. Types of collateral for over-the-counter contracts include cash, letters of credit and, in some cases, other forms of security, none of which are subject to restrictions.

 

DESC does not offset amounts recognized for the right to reclaim cash collateral or the obligation to return cash collateral against amounts recognized for derivative instruments executed with the same counterparty under the same master netting arrangement. DESC had no margin assets or liabilities associated with cash collateral at December 31, 2024 and 2023. See Note 8 for further information about derivatives.

 

To manage price and interest rate risk, DESC holds derivative instruments that are not designated as hedges for accounting purposes. However, to the extent DESC does not hold offsetting positions for such derivatives, it believes these instruments represent economic hedges that mitigate its exposure to fluctuations in commodity prices or interest rates. All income statement activity, including amounts realized upon settlement, is presented in operating expenses and interest charges based on the nature of the underlying risk. For derivative instruments that are not accounted for as cash flow hedges, the cash flows from the derivatives are classified in operating cash flows.

 

Changes in the fair value of derivative instruments result in the recognition of regulatory assets or regulatory liabilities. Realized gains or losses on the derivative instruments are generally recognized when the related transactions impact earnings.

Derivative Instruments Designated as Hedging Instruments

In accordance with accounting guidance pertaining to derivatives and hedge accounting, DESC designated a portion of its derivative instruments as cash flow hedges for accounting purposes. For derivative instruments that are accounted for as cash flow hedges, the cash flows from the derivatives and from the related hedged items are classified in operating cash flows.

Cash Flow Hedges- DESC used interest rate swaps to hedge its exposure to variable interest rates on long-term debt. For transactions in which DESC is hedging the variability of cash flows, changes in the fair value of the derivatives are reported in regulatory assets or liabilities. Any derivative gains or losses reported in regulatory assets or liabilities are reclassified to earnings when the forecasted item is included in earnings, or earlier, if it becomes probable that the forecasted transaction will not occur. For cash flow hedge transactions, hedge accounting is discontinued if the occurrence of the forecasted transaction is no longer probable. At December 31, 2024, all derivatives previously designated as cash flow hedges have settled and are being amortized over the life of the debt.

Pursuant to regulatory orders, interest rate derivatives entered into by DESC after October 2013 were not designated for accounting purposes as cash flow hedges, and fair value changes and settlement amounts related to them have been recorded as regulatory assets and liabilities. Settlement losses on swaps generally have been amortized over the lives of subsequent debt issuances, and gains have been amortized to interest charges or have been applied as otherwise directed by the South Carolina Commission.
Fair Value Measurements

Fair Value Measurements

Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability (exit price) in an orderly transaction between market participants at the measurement date. However, the use of a mid-market pricing convention (the mid-point between bid and ask prices) is permitted. Fair values are based on assumptions that market participants would use when pricing an asset or liability, including assumptions about risk and the risks inherent in valuation techniques and the inputs to valuations. This includes not only the credit standing of counterparties involved and the impact of credit enhancements but also the impact of DESC’s own nonperformance risk on its liabilities. Fair value measurements assume that the transaction occurs in the principal market for the asset or liability (the market with the most volume and activity for the asset or liability from the perspective of the reporting entity), or in the absence of a principal market, the most advantageous market for the asset or liability (the market in which the reporting entity would be able to maximize the amount received or minimize the amount paid). DESC applies fair value measurements to certain assets and liabilities including commodity and interest rate derivative instruments. DESC applies credit adjustments to its derivative fair values in accordance with the requirements described above.

Inputs and Assumptions

Fair value is based on actively-quoted market prices, if available. In the absence of actively-quoted market prices, price information is sought from external sources, including industry publications, and to a lesser extent, broker quotes. When evaluating pricing information provided by Designated Contract Market settlement pricing, other pricing services, or brokers, DESC considers the ability to transact at the quoted price, i.e. if the quotes are based on an active market or an inactive market and to the extent which pricing models are used, if pricing is not readily available. If pricing information from external sources is not available, or if DESC believes that observable pricing is not indicative of fair value, judgment is required to develop the estimates of fair value. In those cases the unobservable inputs are developed and substantiated using historical information, available market data, third-party data and statistical analysis. Periodically, inputs to valuation models are reviewed and revised as needed, based on historical information, updated market data, market liquidity and relationships and changes in third-party sources.

For options and contracts with option-like characteristics where observable pricing information is not available from external sources, DESC generally uses a model that considers time value, the volatility of the underlying commodities and other relevant assumptions when estimating fair value. For contracts with unique characteristics, DESC may estimate fair value using a discounted cash flow approach deemed appropriate in the circumstances and applied consistently from period to period. For individual contracts, the use of different valuation models or assumptions could have a significant effect on the contract’s estimated fair value.

The inputs and assumptions used in measuring fair value include the following:

 

 

Derivative Contracts

Inputs and assumptions

 

Commodity

 

Interest Rate

Forward commodity prices

 

X

 

 

Transaction prices

 

X

 

 

Price volatility

 

X

 

 

Price correlation

 

X

 

 

Volumes

 

X

 

 

Commodity location

 

X

 

 

Interest rates

 

X

 

 

Interest rate curves

 

 

 

X

Credit quality of counterparties and DESC

 

X

 

X

Credit enhancements

 

X

 

X

Time value

 

X

 

X

Notional value

 

 

 

X

 

In addition, investments are measured at fair value utilizing quoted securities prices and indices.

Levels

DESC utilizes the following fair value hierarchy, which prioritizes the inputs to valuation techniques used to measure fair value into three broad levels:

•
Level 1-Quoted prices (unadjusted) in active markets for identical assets and liabilities that it has the ability to access at the measurement date. Instruments categorized in Level 1 primarily consist of cash equivalents and other.
•
Level 2-Inputs other than quoted prices included within Level 1 that are either directly or indirectly observable for the asset or liability, including quoted prices for similar assets or liabilities in active markets, quoted prices for identical or similar assets or liabilities in inactive markets, inputs other than quoted prices that are observable for the asset or liability, and inputs that are derived from observable market data by correlation or other means. Instruments categorized in Level 2 include commodity forwards and interest rate swaps.
•
Level 3-Unobservable inputs for the asset or liability, including situations where there is little, if any, market activity for the asset or liability. Instruments categorized in Level 3 for DESC consist of long-dated commodity derivatives and certain natural gas options.

The fair value hierarchy gives the highest priority to quoted prices in active markets (Level 1) and the lowest priority to unobservable data (Level 3). In some cases, the inputs used to measure fair value might fall in different levels of the fair value hierarchy. In these cases, the lowest level input that is significant to a fair value measurement in its entirety determines the applicable level in the fair value hierarchy. Assessing the significance of a particular input to the fair value measurement in its entirety requires judgment, considering factors specific to the asset or liability.
Debt Issuance Costs

Debt Issuance Costs

DESC defers and amortizes debt issuance costs and debt premiums or discounts over the expected lives of the respective debt issues, considering maturity dates and, if applicable, redemption rights held by others. Deferred debt issuance costs are recorded as a reduction in long-term debt in the Consolidated Balance Sheets. Amortization of the issuance costs is reported as interest charges. As permitted by regulatory authorities, gains or losses resulting from the refinancing or redemption of debt that are probable of recovery through future rates are deferred and amortized.
Environmental

Environmental

An environmental assessment program is maintained to identify and evaluate current and former operations sites that could require environmental clean-up. As site assessments are initiated, estimates are made of the amount of expenditures, if any, deemed necessary to investigate and remediate each site. Environmental remediation liabilities are accrued when the criteria for loss contingencies are met. These estimates are refined as additional information becomes available; therefore, actual expenditures could differ significantly from the original estimates. Probable and estimable costs are accrued related to environmental sites on an undiscounted basis. Amounts estimated and accrued to date for site assessments and clean-up relate solely to regulated operations. Amounts expected to be recovered through rates are recorded in regulatory assets and, if applicable, amortized over approved amortization periods. Other environmental costs are expensed as incurred.
Statement of Operations Presentation

Statement of Operations Presentation

Revenues and expenses arising from regulated businesses are presented within operating income, and all other activities are presented within other income (expense), net.
Operating Revenue

Operating Revenue

Operating revenue is recorded on the basis of services rendered, commodities delivered or contracts settled and includes amounts yet to be billed to customers. DESC collects sales, consumption, consumer utility taxes and sales taxes; however, these amounts are excluded from revenue and are recorded as liabilities until they are remitted to the respective taxing authority.

The primary types of sales and service activities reported as operating revenue for DESC are as follows:

Revenue from Contracts with Customers

•
Regulated electric sales consist primarily of state-regulated retail electric sales, and federally-regulated wholesale electric sales and electric transmission services;
•
Regulated gas sales consist primarily of state-regulated natural gas sales and related distribution services; and
•
Other regulated revenue consists primarily of miscellaneous service revenue from electric and gas distribution operations and sales of excess electric capacity and other commodities.

Other Revenue

•
Other revenue consists primarily of alternative revenue programs, gains and losses from derivative instruments not subject to hedge accounting and lease revenues.

DESC records refunds to customers as required by the South Carolina Commission as a reduction to regulated electric sales or regulated gas sales, as applicable. Revenues from electric and gas sales are recognized over time, as the customers of DESC consume gas and electricity as it is delivered. Sales of products and services typically transfer control and are recognized as revenue upon delivery of the product or service. The customer is able to direct the use of, and obtain substantially all of the benefits from, the product at the time the product is delivered. The contract with the customer states the final terms of the sale, including the description, quantity and price of each product or service purchased. Payment for most sales and services varies by contract type, but is typically due within a month of billing.

 

DESC customers subject to an electric fuel cost recovery component or a PGA are billed based on a fuel or cost of gas factor calculated in accordance with cost recovery procedures approved by the South Carolina Commission and subject to adjustment periodically. Any difference between actual costs and amounts contained in rates is adjusted through revenue and is deferred and included when making the next adjustment to the cost recovery factors.

 

Certain amounts deferred for the WNA arise under specific arrangements with regulators rather than customers and are accounted for as an alternative revenue program. This alternative revenue is included within Other operating revenues, separate from revenue arising from contracts with customers, in the month such adjustments are deferred within regulatory accounts. As permitted, DESC has elected to reduce the regulatory accounts in the period when such amounts are reflected on customer bills without affecting operating revenues.

 

Performance obligations which have not been satisfied by DESC relate primarily to demand or standby service for natural gas. Demand or standby charges for natural gas arise when an industrial customer reserves capacity on assets controlled by the service provider and may use that capacity to move natural gas it has acquired from other suppliers. For all periods presented, the amount of revenue recognized by DESC for these charges is equal to the amount of consideration DESC has a right to invoice and corresponds directly to the value transferred to the customer.
Leases

Leases

DESC leases certain assets including vehicles, real estate, office equipment and other assets under both operating and finance leases. For operating leases, rent expense is recognized on a straight-line basis over the term of the lease agreement, subject to regulatory framework. Rent expense associated with operating leases, short-term leases and variable leases is primarily recorded in other operations and maintenance expense in the Consolidated Statements of Comprehensive Income. Amortization expense and interest charges associated with finance leases are deferred within regulatory assets in the Consolidated Balance Sheets and amortized into the Consolidated Statements of Comprehensive Income.

Certain leases include one or more options to renew, with renewal terms that can extend the lease from one to 70 years. The exercise of renewal options is solely at DESC’s discretion and is included in the lease term if the option is reasonably certain to be exercised. A right-of-use asset and corresponding lease liability for leases with original lease terms of one year or less are not included in the Consolidated Balance Sheets, unless such leases contain renewal options that DESC is reasonably certain will be exercised.

The determination of the discount rate utilized has a significant impact on the calculation of the present value of the lease liability included in the Consolidated Balance Sheets. For DESC’s leased assets, the discount rate implicit in the lease is generally unable to be determined from a lessee perspective. As such, DESC uses internally-developed incremental borrowing rates as a discount rate in the calculation of the present value of the lease liability. The incremental borrowing rates are determined based on an analysis of DESC’s publicly available secured borrowing rates over various lengths of time that most closely correspond to DESC’s lease maturities.
New Accounting Standards

New Accounting Standards

Segment Disclosures

In November 2023, the FASB issued revised accounting guidance for reportable segments. The revised guidance requires disclosure of significant segment expenses and other segment items on an annual and interim basis and to provide in interim periods all disclosures about a reportable segment’s profit or loss and assets that are currently required annually. Additionally, it requires disclosure of the title and position of the CODM. The revised guidance does not change how an entity identifies its operating

segments, aggregates them or applies the quantitative thresholds to determine its reportable segments. The new standard is effective for fiscal years beginning after December 15, 2023, and interim periods within fiscal years beginning after December 15, 2024, with early adoption permitted and requires retrospective application to all prior periods presented. This revised guidance only impacted DESC’s disclosures with no impacts to its results of operations, cash flows or financial condition.

Income Tax Disclosures

In December 2023, the FASB issued revised accounting guidance for income taxes. The revised guidance requires disclosure of disaggregated information about an entity’s effective tax rate reconciliation as well as additional information on income taxes paid. The new standard is effective for fiscal years beginning after December 15, 2024, with early adoption permitted and allows either prospective or retrospective application. DESC expects this revised guidance to only impact its disclosures with no impacts to its results of operations, cash flows or financial condition.

Climate-Related Disclosures

In March 2024, the SEC issued guidance for climate-related disclosures. The guidance requires disclosure of the financial statement impacts of severe weather events and other natural conditions, including amounts capitalized or expensed as well as any associated recoveries. In addition, the guidance requires disclosure of amounts related to renewable energy credits or carbon offsets if utilized as a material component of plans to achieve climate-related targets or goals. This guidance is currently subject to a stay issued by the SEC. Should this guidance become effective, DESC expects it to only impact its disclosures with no impacts to its results of operations, cash flows or financial condition.

Expense Disaggregation Disclosures

In November 2024, the FASB issued revised accounting guidance for income statement expense disaggregation disclosures. The revised guidance requires disclosure of disaggregated information about specific expense categories in commonly presented income statement expense captions. The new standard is effective for fiscal years beginning after December 15, 2026, and interim periods within fiscal years beginning after December 15, 2027, with early adoption permitted and allows either prospective or retrospective application. DESC expects this revised guidance to only impact its disclosures with no impacts to its results of operations, cash flows or financial condition.
v3.25.0.1
Summary of Significant Accounting Policies (Tables)
 12 Months Ended
Dec. 31, 2024
Accounting Policies [Abstract]  
Schedule of Weighted Average Depreciation Rates The composite weighted-average depreciation rates for utility plant by function were as follows:

Year Ended December 31,

 

2024

 

 

2023

 

 

2022

 

(percent)

 

 

 

 

 

 

 

 

 

Generation

 

 

2.33

 

 

 

2.33

 

 

 

2.34

 

Transmission

 

 

2.53

 

 

 

2.54

 

 

 

2.36

 

Distribution

 

 

2.53

 

 

 

2.57

 

 

 

2.59

 

Storage

 

 

2.75

 

 

 

2.83

 

 

 

2.93

 

General and other

 

 

3.15

 

 

 

3.16

 

 

 

3.35

 
Schedule of Cash and Cash Equivalents

The following table provides a reconciliation of the total cash, restricted cash and equivalents reported within DESC’s Consolidated Balance Sheets to the corresponding amounts reported within DESC’s Consolidated Statements of Cash Flows for the years ended December 31, 2024, 2023 and 2022:

 

 

 

Cash, Restricted Cash and Equivalents at End/Beginning of Year

 

 

 

December 31, 2024

 

 

December 31, 2023

 

 

December 31, 2022

 

 

December 31, 2021

 

(millions)

 

 

 

 

 

 

 

 

 

 

 

 

Cash and cash equivalents

 

$

—

 

 

$

1

 

 

$

11

 

 

$

30

 

Restricted cash and equivalents(1)

 

 

—

 

 

 

—

 

 

 

—

 

 

 

24

 

Cash, restricted cash and equivalents shown in the
   Consolidated Statements of Cash Flows

 

$

—

 

 

$

1

 

 

$

11

 

 

$

54

 
(1)
Restricted cash and equivalent balances are presented within other current assets on the Consolidated Balance Sheets.
Schedule of Input And Assumptions Used in Measuring Fair Value

The inputs and assumptions used in measuring fair value include the following:

 

 

Derivative Contracts

Inputs and assumptions

 

Commodity

 

Interest Rate

Forward commodity prices

 

X

 

 

Transaction prices

 

X

 

 

Price volatility

 

X

 

 

Price correlation

 

X

 

 

Volumes

 

X

 

 

Commodity location

 

X

 

 

Interest rates

 

X

 

 

Interest rate curves

 

 

 

X

Credit quality of counterparties and DESC

 

X

 

X

Credit enhancements

 

X

 

X

Time value

 

X

 

X

Notional value

 

 

 

X

 

In addition, investments are measured at fair value utilizing quoted securities prices and indices.
v3.25.0.1
Rate and Other Regulatory Matters (Tables)
 12 Months Ended
Dec. 31, 2024
Regulated Operations [Abstract]  
Schedule of Regulatory Assets and Liabilities

At December 31,

 

2024

 

 

2023

 

(millions)

 

 

 

 

 

 

Regulatory assets:

 

 

 

 

 

 

NND Project costs(1)

 

$

138

 

 

$

138

 

AROs(2)

 

 

8

 

 

 

44

 

Deferred employee benefit plan costs(3)

 

 

8

 

 

 

11

 

Other unrecovered plant(4)

 

 

18

 

 

 

19

 

DSM programs(5)

 

 

24

 

 

 

22

 

Cost of fuel and purchased gas under-collections(6)

 

 

35

 

 

 

154

 

Other

 

 

68

 

 

 

56

 

Regulatory assets - current

 

 

299

 

 

 

444

 

NND Project costs(1)

 

 

1,811

 

 

 

1,949

 

AROs(2)

 

 

695

 

 

 

379

 

Deferred employee benefit plan costs(3)

 

 

94

 

 

 

118

 

Interest rate hedges(7)

 

 

167

 

 

 

168

 

Other unrecovered plant(4)

 

 

89

 

 

 

66

 

DSM programs(5)

 

 

49

 

 

 

46

 

Environmental remediation costs(8)

 

 

42

 

 

 

34

 

Deferred storm damage costs(9)

 

 

76

 

 

 

40

 

Deferred transmission operating costs(10)

 

 

72

 

 

 

74

 

Derivatives(11)

 

 

95

 

 

 

103

 

Other(12)

 

 

152

 

 

 

130

 

Regulatory assets - noncurrent

 

 

3,342

 

 

 

3,107

 

Total regulatory assets

 

$

3,641

 

 

$

3,551

 

Regulatory liabilities:

 

 

 

 

 

 

Monetization of guaranty settlement(13)

 

$

67

 

 

$

67

 

Income taxes refundable through future rates(14)

 

 

24

 

 

 

37

 

Reserve for refunds to electric utility customers(15)

 

 

73

 

 

 

83

 

Derivatives(11)

 

 

27

 

 

 

12

 

Other

 

 

10

 

 

 

6

 

Regulatory liabilities - current

 

 

201

 

 

 

205

 

Monetization of guaranty settlement(13)

 

 

568

 

 

 

635

 

Income taxes refundable through future rates(14)

 

 

820

 

 

 

839

 

Asset removal costs(16)

 

 

598

 

 

 

633

 

Reserve for refunds to electric utility customers(15)

 

 

161

 

 

 

237

 

Derivatives(11)

 

 

328

 

 

 

229

 

Other

 

 

13

 

 

 

6

 

Regulatory liabilities - noncurrent

 

 

2,488

 

 

 

2,579

 

Total regulatory liabilities

 

$

2,689

 

 

$

2,784

 
(1)
Reflects expenditures associated with the NND Project, which pursuant to the SCANA Merger Approval Order, will be recovered from electric service customers over a 20-year period ending in 2039.
(2)
Represents uncollected costs, including deferred depreciation and accretion expense, related to legal obligations associated with the future retirement of generation, transmission and distribution properties. The AROs primarily relate to DESC’s electric generating facilities, including Summer, and are expected to be recovered over the related property lives and periods of decommissioning which may range up to approximately 105 years. In addition, the balance at December 31, 2024 reflects amounts related to the EPA’s May 2024 final rule concerning CCR as discussed in Note 12.
(3)
Employee benefit plan costs have historically been recovered as they have been recorded under GAAP. Deferred employee benefit plan costs represent amounts of pension and other postretirement benefit costs which were accrued as liabilities and treated as regulatory assets pursuant to FERC guidance, and costs deferred pursuant to specific South Carolina Commission regulatory orders. DESC expects to recover deferred pension costs through utility rates over periods through 2044. DESC expects to recover other deferred benefit costs through utility rates, primarily over average service periods of participating employees up to 11 years.
(4)
Represents the carrying value of coal-fired generating units, including related materials and supplies inventory, retired from service prior to being fully depreciated. DESC is amortizing these amounts through cost of service rates following depreciation amounts that were designed to recover the retired units cost over their previous estimated remaining useful lives, which has been estimated to be through 2025. Based on current projections of remaining decommissioning costs, projected recovery is expected to extend through 2039. In addition, amounts include unrecovered costs of existing meters and equipment retired from service prior to being fully depreciated as part of the Advanced Metering Infrastructure project, which are being recovered through rates through 2028. This amount also includes certain inventory and preliminary survey and investigation charges being amortized through 2026 related to the transition or conversion from coal to gas fired generation at certain facilities.
(5)
Primarily represents deferred costs associated with electric demand reduction programs, and such deferred costs are currently being recovered over three years through an approved rate rider.
(6)
Represents amounts under- or over-collected from customers pursuant to the cost of fuel and purchased gas components approved by the South Carolina Commission.
(7)
Represents settled interest rate derivatives designated as cash flow hedges expected to be amortized to interest expense over the lives of the underlying debt through 2065.
(8)
Reflects amounts associated with the assessment and clean-up of sites currently or formerly owned by DESC. Such remediation costs are expected to be recovered over periods of up to 24 years. See Note 12 for additional information.
(9)
Represents storm restoration costs for which DESC expects to receive future recovery. Pursuant to the settlement agreement approved in DESC’s retail electric base rate case in August 2024, for costs incurred prior to September 2024, DESC expects to receive future recovery through customer rates through 2034 and for costs incurred effective September 2024, DESC expects to receive future recovery through customer rates of approximately $2 million each year. Unamortized amounts are included in rate base and are earning a current return.
(10)
Includes deferred depreciation and property taxes associated with certain transmission assets for which DESC expects future recovery from customers through 2062. Unamortized amounts are included in rate base and earning a current return.
(11)
Represents changes in the fair value of derivatives, excluding separately presented interest rate hedges, that following settlement are expected to be recovered from or refunded to customers.
(12)
Various other regulatory assets are expected to be recovered through rates over varying periods through 2078.
(13)
Represents proceeds related to the monetization of the Toshiba Settlement. In accordance with the SCANA Merger Approval Order, this balance, net of amounts that may be required to satisfy liens, will be refunded to electric customers over a 20-year period ending in 2039.
(14)
Includes (i) excess deferred income taxes arising from the remeasurement of deferred income taxes in connection with the enactment of the 2017 Tax Reform Act (certain of which are protected under normalization rules and will be amortized over the remaining lives of related property, and certain of which will be amortized to the benefit of customers over prescribed periods as instructed by regulators) and (ii) deferred income taxes arising from investment tax credits, offset by (iii) deferred income taxes that arise from utility operations that have not been included in customer rates (a portion of which relate to depreciation and are expected to be recovered over the remaining lives of the related property which may range up to 85 years). See Note 7 for additional information.
(15)
Reflects amounts previously collected from retail electric customers of DESC for the NND Project to be credited to customers over an estimated 11-year period effective February 2019 in connection with the SCANA Merger Approval Order.
(16)
Represents estimated net collections through depreciation rates of amounts to be expended for the removal of assets in the future.
v3.25.0.1
Operating Revenue (Tables)
 12 Months Ended
Dec. 31, 2024
Revenue Recognition and Deferred Revenue [Abstract]  
Disaggregation of Revenue

DESC’s operating revenue consists of the following:

 

Year Ended December 31,

 

2024

 

 

2023

 

 

2022

 

(millions)

 

Electric

 

 

Gas

 

 

Electric

 

 

Gas

 

 

Electric

 

 

Gas

 

Customer class:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Residential

 

$

1,259

 

 

$

302

 

 

$

1,160

 

 

$

268

 

 

$

1,375

 

 

$

303

 

Commercial

 

 

855

 

 

 

126

 

 

 

820

 

 

 

129

 

 

 

968

 

 

 

184

 

Industrial

 

 

389

 

 

 

68

 

 

 

372

 

 

 

77

 

 

 

533

 

 

 

166

 

Other

 

 

123

 

 

 

25

 

 

 

150

 

 

 

24

 

 

 

203

 

 

 

23

 

Revenues from contracts with customers

 

 

2,626

 

 

 

521

 

 

 

2,502

 

 

 

498

 

 

 

3,079

 

 

 

676

 

Other revenues

 

 

25

 

 

 

1

 

 

 

27

 

 

 

1

 

 

 

27

 

 

 

1

 

Total Operating Revenues

 

$

2,651

 

 

$

522

 

 

$

2,529

 

 

$

499

 

 

$

3,106

 

 

$

677

 

 
Balance and Activity Related to Contract Costs Deferred as Regulatory Assets

Balances and activity related to contract costs deferred as regulatory assets were as follows:

 

 

Regulatory Assets

 

(millions)

 

2024

 

 

2023

 

Beginning balance

 

$

11

 

 

$

9

 

Additional costs

 

 

—

 

 

 

3

 

Amortization

 

 

(1

)

 

 

(1

)

Ending balance

 

$

10

 

 

$

11

 
v3.25.0.1
Long-Term and Short-Term Debt (Tables)
 12 Months Ended
Dec. 31, 2024
Debt Disclosure [Abstract]  
Schedule of Debt

Long-term debt by type with related weighted-average coupon rates and maturities at December 31, 2024 and 2023 is as follows:

 

At December 31,

 

2024
Weighted-
average
Coupon(1)

 

 

2024

 

 

2023

 

(millions, except percentages)

 

 

 

 

 

 

 

 

 

DESC:

 

 

 

 

 

 

 

 

 

First Mortgage Bonds, 2.30% to 6.625%, due 2028 to 2065

 

 

5.23

%

 

$

4,134

 

 

$

4,134

 

Tax-Exempt Financings:(2)

 

 

 

 

 

 

 

 

 

Variable rate due 2038

 

 

3.70

%

 

 

35

 

 

 

35

 

3.625% and 4.00%, due 2028 and 2033

 

 

3.90

%

 

 

54

 

 

 

54

 

Other

 

 

3.58

%

 

 

1

 

 

 

1

 

GENCO:

 

 

 

 

 

 

 

 

 

Tax-Exempt Financing, variable rate due 2038

 

 

3.70

%

 

 

33

 

 

 

33

 

Affiliated note, 5.31% due 2027

 

 

5.31

%

 

 

230

 

 

 

230

 

Total principal

 

 

 

 

 

4,487

 

 

 

4,487

 

Affiliated and related party payables

 

 

 

 

 

—

 

 

 

(230

)

Unamortized discount, premium and debt issuance costs, net

 

 

 

 

 

(37

)

 

 

(38

)

Finance leases

 

 

 

 

 

2

 

 

 

4

 

Total long-term debt

 

 

 

 

$

4,452

 

 

$

4,223

 
(1)
Represents weighted-average coupon rates for debt outstanding as of December 31, 2024.
(2)
Industrial revenue bonds totaling $68 million are secured by letters of credit that expire, subject to renewal, in the fourth quarter of 2025.
Schedule of Principal Payments of Long-Term Debt

Based on stated maturity dates rather than early redemption dates that could be elected by instrument holders, the scheduled principal payments of long-term debt at December 31, 2024, were as follows:

 

(millions, except percentages)

 

2025

 

 

2026

 

 

2027

 

 

2028

 

 

2029

 

 

Thereafter

 

 

Total

 

First Mortgage Bonds

 

$

—

 

 

$

—

 

 

$

—

 

 

$

53

 

 

$

—

 

 

$

4,081

 

 

$

4,134

 

Tax-Exempt Financings

 

 

—

 

 

 

—

 

 

 

—

 

 

 

39

 

 

 

—

 

 

 

83

 

 

 

122

 

Other

 

 

—

 

 

 

—

 

 

 

230

 

 

 

—

 

 

 

—

 

 

 

1

 

 

 

231

 

Total

 

$

—

 

 

$

—

 

 

$

230

 

 

$

92

 

 

$

—

 

 

$

4,165

 

 

$

4,487

 

Weighted-average coupon

 

 

 

 

 

 

 

 

5.31

%

 

 

4.14

%

 

 

 

 

 

5.21

%

 

 

 
Schedule of Line of Credit Facilities

DESC’s share of commercial paper and letters of credit outstanding under its joint credit facility with Dominion Energy, were as follows:

 

(millions)

 

Facility Limit

 

 

Outstanding
Commercial
Paper(1)

 

 

Outstanding
Letters of
Credit

 

At December 31, 2024

 

 

 

 

 

 

 

 

 

Joint revolving credit facility(2)(3)

 

$

1,000

 

 

$

250

 

 

$

—

 

At December 31, 2023

 

 

 

 

 

 

 

 

 

Joint revolving credit facility(2)

 

$

1,000

 

 

$

254

 

 

$

—

 
(1)
The weighted-average interest rate of the outstanding commercial paper supported by the credit facility was 4.76% and 5.70% at December 31, 2024 and 2023, respectively.
(2)
A maximum of $1.0 billion of the facility is available to DESC, assuming adequate capacity is available after giving effect to uses by co-borrowers Dominion Energy and Virginia Power. A sub-limit for DESC is set within the facility limit but can be changed at the option of the co-borrowers multiple times per year. At December 31, 2024, the sub-limit for DESC was $500 million. If DESC has liquidity needs in excess of its sub-limit, the sub-limit may be changed or such needs may be satisfied through short-term borrowings from Dominion Energy. This credit facility matures in June 2026, with the potential to be extended by the borrowers to June 2028. The credit facility can be used to support bank borrowings and the issuance of commercial paper, as well as to support up to $1.0 billion (or the sub-limit, whichever is less) of letters of credit.
(3)
In May 2024, the joint revolving credit facility was amended to remove Questar Gas as a co-borrower.
v3.25.0.1
Income Taxes (Tables)
 12 Months Ended
Dec. 31, 2024
Income Tax Disclosure [Abstract]  
Details of Income Tax Expense for Continuing Operations Including Noncontrolling Interests

 

Year Ended December 31,

 

2024

 

 

2023

 

 

2022

 

(millions)

 

 

 

 

 

 

 

 

 

Current:

 

 

 

 

 

 

 

 

 

Federal

 

$

(6

)

 

$

91

 

 

$

(69

)

State

 

 

7

 

 

 

(70

)

 

 

(3

)

Total current expense (benefit)

 

 

1

 

 

 

21

 

 

 

(72

)

Deferred:

 

 

 

 

 

 

 

 

 

Federal

 

 

 

 

 

 

 

 

 

Taxes before operating loss carryforwards and investment tax credits

 

 

16

 

 

 

(72

)

 

 

135

 

Tax utilization expense (benefit) of operating loss carryforwards

 

 

36

 

 

 

43

 

 

 

33

 

State

 

 

13

 

 

 

95

 

 

 

36

 

Total deferred expense

 

 

65

 

 

 

66

 

 

 

204

 

Investment tax credits

 

 

(1

)

 

 

(2

)

 

 

(1

)

Total income tax expense

 

$

65

 

 

$

85

 

 

$

131

 
Schedule of Effective Income Tax Rate Reconciliation

 

Year Ended December 31,

 

2024

 

 

2023

 

 

2022

 

U.S. statutory rate

 

 

21.0

%

 

 

21.0

%

 

 

21.0

%

Increases (reductions) resulting from:

 

 

 

 

 

 

 

 

 

State taxes, net of federal benefit

 

 

4.0

 

 

 

4.1

 

 

 

4.7

 

Amortization of federal investment tax credits

 

 

(0.3

)

 

 

(0.3

)

 

 

(0.2

)

Reversal of excess deferred income taxes

 

 

(5.6

)

 

 

(4.7

)

 

 

(4.6

)

Settlements of uncertain tax positions

 

 

(3.5

)

 

 

(2.2

)

 

 

—

 

Other

 

 

(0.1

)

 

 

(0.2

)

 

 

(0.2

)

Effective tax rate

 

 

15.5

%

 

 

17.7

%

 

 

20.7

%
Schedule of Deferred Income Taxes

DESC’s deferred income taxes consist of the following:

 

At December 31,

 

2024

 

 

2023

 

(millions)

 

 

 

 

 

 

Deferred income taxes:

 

 

 

 

 

 

Total deferred income tax assets

 

$

662

 

 

$

728

 

Total deferred income tax liabilities

 

 

2,059

 

 

 

2,033

 

Total net deferred income tax liabilities

 

$

1,397

 

 

$

1,305

 

Total deferred income taxes:

 

 

 

 

 

 

Depreciation method and plant basis differences

 

$

1,271

 

 

$

1,203

 

Excess deferred income taxes

 

 

(203

)

 

 

(212

)

Unrecovered nuclear plant cost

 

 

420

 

 

 

450

 

DESC rate refund

 

 

(49

)

 

 

(67

)

Toshiba Settlement

 

 

(133

)

 

 

(147

)

Nuclear decommissioning

 

 

(60

)

 

 

(51

)

Deferred state income taxes

 

 

289

 

 

 

274

 

Federal benefit of deferred state income taxes

 

 

(61

)

 

 

(60

)

Deferred fuel, purchased energy and gas costs

 

 

11

 

 

 

32

 

Pension benefits

 

 

35

 

 

 

35

 

Other postretirement benefits

 

 

(20

)

 

 

(17

)

Loss and credit carryforwards

 

 

(153

)

 

 

(185

)

Other

 

 

50

 

 

 

50

 

Total net deferred income tax liabilities

 

$

1,397

 

 

$

1,305

 

Deferred investment tax credits

 

 

12

 

 

 

13

 

Total deferred taxes and deferred investment tax credits

 

$

1,409

 

 

$

1,318

 
Summary of Tax Credit Carryforwards

At December 31, 2024, DESC had the following deductible loss and credit carryforwards:

 

(millions)

 

Deductible Amount

 

 

Deferred Tax Asset(1)

 

 

Expiration Period

Federal losses

 

$

361

 

 

$

76

 

 

2037

Federal production and other credits

 

 

—

 

 

 

22

 

 

2036-2038

State losses

 

 

887

 

 

 

44

 

 

2037-2042

State investment and other credits

 

 

—

 

 

 

41

 

 

2026-2033

Total

 

$

1,248

 

 

$

183

 

 

 
(1)
Includes $38 million of unrecognized tax benefits.
Schedule of Unrecognized Tax Benefits Roll Forward

A reconciliation of changes in DESC’s unrecognized tax benefits follows:

 

(millions)

 

2024

 

 

2023

 

 

2022

 

Balance at January 1,

 

$

62

 

 

$

68

 

 

$

62

 

Increases-prior period positions

 

 

5

 

 

 

5

 

 

 

6

 

Decreases-prior period positions

 

 

(16

)

 

 

(11

)

 

 

(1

)

Increases-current period positions

 

 

—

 

 

 

—

 

 

 

1

 

Settlements with tax authorities

 

 

(13

)

 

 

—

 

 

 

—

 

Balance at December 31,

 

$

38

 

 

$

62

 

 

$

68

 

Certain unrecognized tax benefits, or portions thereof, if recognized, would affect the effective tax rate. Changes in these unrecognized tax benefits may result from remeasurement of amounts expected to be realized, settlements with tax authorities and expiration of statutes of limitations. If recognized, all the unrecognized tax benefits would impact the effective tax rate.
v3.25.0.1
Derivative Financial Instruments (Tables)
 12 Months Ended
Dec. 31, 2024
Derivative Instruments and Hedging Activities Disclosure [Abstract]  
Offsetting Assets

The table below presents derivative balances by type of financial instrument, if the gross amounts recognized in the Consolidated Balance Sheets were netted with derivative instruments and cash collateral received or paid.

 

 

December 31, 2024

 

 

December 31, 2023

 

 

 

 

 

 

Gross Amounts Not Offset
in the Consolidated
Balance Sheet(1)

 

 

 

 

 

 

 

 

Gross Amounts Not Offset
in the Consolidated
Balance Sheet(1)

 

 

 

 

(millions)

 

Gross Assets
Presented in the
Consolidated
Balance Sheet

 

 

Financial
Instruments

 

 

Cash
Collateral
Received

 

 

Net
Amounts

 

 

Gross Assets
Presented in the
Consolidated
Balance Sheet

 

 

Financial
Instruments

 

 

Cash
Collateral
Received

 

 

Net
Amounts

 

Interest rate contracts:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Over-the-counter

 

$

2

 

 

$

—

 

 

$

—

 

 

$

2

 

 

$

—

 

 

$

—

 

 

$

—

 

 

$

—

 

Commodity contracts:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Over-the-counter

 

 

81

 

 

 

—

 

 

 

—

 

 

 

81

 

 

 

 

 

 

 

 

 

 

 

 

 

Total derivatives

 

$

83

 

 

$

—

 

 

$

—

 

 

$

83

 

 

$

—

 

 

$

—

 

 

$

—

 

 

$

—

 

(1) Excludes derivative assets of $289 million and $176 million at December 31, 2024 and December 31, 2023, respectively, which are not subject to master netting or similar arrangements.
Offsetting Liabilities

 

 

December 31, 2024

 

 

December 31, 2023

 

 

 

 

 

 

Gross Amounts Not Offset
in the Consolidated
Balance Sheet(1)

 

 

 

 

 

 

 

 

Gross Amounts Not Offset
in the Consolidated
Balance Sheet(1)

 

 

 

 

(millions)

 

Gross
Liabilities
Presented in the
Consolidated
Balance Sheet

 

 

Financial
Instruments

 

 

Cash
Collateral
Paid

 

 

Net
Amounts

 

 

Gross
Liabilities
Presented in the
Consolidated
Balance Sheet

 

 

Financial
Instruments

 

 

Cash
Collateral
Paid

 

 

Net
Amounts

 

Interest rate contracts:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Over-the-counter

 

$

1

 

 

$

—

 

 

$

—

 

 

$

1

 

 

$

4

 

 

$

—

 

 

$

—

 

 

$

4

 

Total derivatives

 

$

1

 

 

$

—

 

 

$

—

 

 

$

1

 

 

$

4

 

 

$

—

 

 

$

—

 

 

$

4

 

(1) DESC did not have any derivative liabilities at December 31, 2024 and December 31, 2023, respectively, which were not subject to master netting or similar arrangements.
Schedule of Volume of Derivative Activity

The following table presents the volume of derivative activity at December 31, 2024. These volumes are based on open derivative positions and represent the combined absolute value of their long and short positions.

 

 

 

Current

 

 

Noncurrent

 

 

 

 

 

 

 

 

Natural Gas (bcf):

 

 

 

 

 

 

Basis(1)

 

 

32

 

 

 

30

 

Electricity (MWh in millions):

 

 

 

 

 

 

Fixed price

 

 

2

 

 

 

21

 

Interest rate(2) (in millions)

 

$

—

 

 

$

71

 
(1)
Includes options.
(2)
Maturity is determined based on final settlement period.
Fair Value of Derivatives

The following table presents the fair values of derivatives and where they are presented in the Consolidated Balance Sheets:

 

 

Assets

 

Liabilities

 

(millions)

 

 

 

 

At December 31, 2024

 

 

 

 

Current derivatives not under cash flow hedge accounting

 

 

 

 

Commodity

$

63

 

$

—

 

Total current derivatives

$

63

 

$

—

 

Noncurrent derivatives not under cash flow hedge accounting

 

 

 

 

Commodity

$

307

 

$

—

 

Interest rate

 

2

 

 

1

 

Total noncurrent derivatives

 

309

 

 

1

 

Total derivatives

$

372

 

$

1

 

At December 31, 2023

 

 

 

 

Current derivatives not under cash flow hedge accounting

 

 

 

 

Commodity

$

9

 

$

—

 

Total current derivatives

$

9

 

$

—

 

Noncurrent derivatives not under cash flow hedge accounting

 

 

 

 

Commodity

$

167

 

$

—

 

Interest rate

 

—

 

 

4

 

Total noncurrent derivatives

 

167

 

 

4

 

Total derivatives

$

176

 

$

4

 
Derivatives in Cash Flow Hedging Relationships

The following tables present the gains and losses on derivatives, as well as where the associated activity is presented in the Consolidated Balance Sheets and Statements of Comprehensive Income:

Derivatives in Cash Flow Hedging Relationships

(millions)

 

Increase (Decrease) in Derivatives Subject to Regulatory Treatment(1)

 

Year Ended December 31, 2024

 

 

 

Derivative type and location of gains (losses):

 

 

 

Interest rate

 

$

1

 

Total

 

$

1

 

Year Ended December 31, 2023

 

 

 

Derivative type and location of gains (losses):

 

 

 

Interest rate

 

$

—

 

Total

 

$

—

 

Year Ended December 31, 2022

 

 

 

Derivative type and location of gains (losses):

 

 

 

Interest rate

 

$

11

 

Total

 

$

11

 

 

(1)
Represents net derivative activity deferred into and amortized out of regulatory assets/liabilities. Amounts deferred into regulatory assets/ liabilities have no associated effect in the Consolidated Statements of Comprehensive Income.
Derivatives Not Designated as Hedging Instruments

Derivatives Not designated as Hedging Instruments

(millions)

 

Amount of Gain (Loss) Recognized in Income on Derivatives(1)

 

Year Ended December 31,

 

2024

 

 

2023

 

 

2022

 

Derivative type and location of gains (losses):

 

 

 

 

 

 

 

 

 

Commodity:

 

 

 

 

 

 

 

 

 

Purchased power

 

$

3

 

 

$

6

 

 

$

77

 

Fuel used in electric generation

 

 

1

 

 

 

—

 

 

 

—

 

Interest rate:

 

 

 

 

 

 

 

 

 

Interest charges

 

 

(1

)

 

 

(2

)

 

 

(2

)

Total

 

$

3

 

 

$

4

 

 

$

75

 
(1)
Includes derivative activity amortized out of regulatory assets/liabilities. Amounts deferred into regulatory assets/liabilities have no associated effect in the Consolidated Statements of Comprehensive Income.
v3.25.0.1
Fair Value Measurements, Including Derivatives (Tables)
 12 Months Ended
Dec. 31, 2024
Fair Value Disclosures [Abstract]  
Schedule of Quantitative Information About Level 3 Fair Value Measurements

The following table presents DESC’s quantitative information about Level 3 fair value measurements at December 31, 2024. The range and weighted-average are presented in dollars for market price inputs and percentages for price volatility.

 

 

Fair Value (millions)

 

 

Valuation Techniques

 

Unobservable Input

 

Range

 

Weighted-average(1)

Assets

 

 

 

 

 

 

 

 

 

 

 

Physical forwards:

 

 

 

 

 

 

 

 

 

 

 

Electricity

 

$

289

 

 

Discounted cash flow

 

Market price (per MWh)(3)

 

31-95

 

55

Physical options:

 

 

 

 

 

 

 

 

 

 

 

Natural gas(2)

 

$

81

 

 

Option model

 

Market price (per Dth)(3)

 

2-7

 

4

 

 

 

 

 

 

 

Price volatility(4)

 

11%-73%

 

47%

Total assets

 

$

370

 

 

 

 

 

 

 

 

 
(1)
Averages weighted by volume.
(2)
Includes basis.
(3)
Represents market prices beyond defined terms for Levels 1 and 2.
(4)
Represents volatilities unrepresented in published markets.
Schedule of Sensitivity of The Fair Value Measurements To Changes in The Significant Unobservable Inputs

Sensitivity of the fair value measurements to changes in the significant unobservable inputs is as follows:

Significant Unobservable Inputs

 

Position

 

Change to Input

 

Impact on Fair Value Measurement

Market price

 

Buy

 

Increase (decrease)

 

Gain (loss)

Market price

 

Sell

 

Increase (decrease)

 

Loss (gain)

Price volatility

 

Buy

 

Increase (decrease)

 

Gain (loss)

Price volatility

 

Sell

 

Increase (decrease)

 

Loss (gain)

 
Schedule of Assets and Liabilities Measured at Fair Value on Recurring Basis

The following table presents DESC’s assets and liabilities that are measured at fair value on a recurring basis for each hierarchy level, including both current and noncurrent portions:

 

 

Level 1

 

 

Level 2

 

 

Level 3

 

 

Total

 

(millions)

 

 

 

 

 

 

 

 

 

 

 

 

At December 31, 2024

 

 

 

 

 

 

 

 

 

 

 

 

Assets

 

 

 

 

 

 

 

 

 

 

 

 

Derivatives:

 

 

 

 

 

 

 

 

 

 

 

 

Commodity

 

$

—

 

 

$

—

 

 

$

370

 

 

$

370

 

Interest rate

 

 

—

 

 

 

2

 

 

 

—

 

 

 

2

 

Investments:

 

 

 

 

 

 

 

 

 

 

 

 

Cash equivalents and other

 

 

29

 

 

 

—

 

 

 

—

 

 

 

29

 

Total assets

 

$

29

 

 

$

2

 

 

$

370

 

 

$

401

 

Liabilities

 

 

 

 

 

 

 

 

 

 

 

 

Derivatives:

 

 

 

 

 

 

 

 

 

 

 

 

Interest rate

 

$

—

 

 

$

1

 

 

$

—

 

 

$

1

 

Total liabilities

 

$

—

 

 

$

1

 

 

$

—

 

 

$

1

 

At December 31, 2023

 

 

 

 

 

 

 

 

 

 

 

 

Assets

 

 

 

 

 

 

 

 

 

 

 

 

Derivatives:

 

 

 

 

 

 

 

 

 

 

 

 

Commodity

 

$

—

 

 

$

—

 

 

$

176

 

 

$

176

 

Total assets

 

$

—

 

 

$

—

 

 

$

176

 

 

$

176

 

Liabilities

 

 

 

 

 

 

 

 

 

 

 

 

Derivatives:

 

 

 

 

 

 

 

 

 

 

 

 

Interest rate

 

$

—

 

 

$

4

 

 

$

—

 

 

$

4

 

Total liabilities

 

$

—

 

 

$

4

 

 

$

—

 

 

$

4

 
Schedule of Assets and Liabilities Measured at Fair Value on Recurring Basis and included in Level 3

The following table presents the net change in DESC’s assets and liabilities measured at fair value on a recurring basis and included in the Level 3 fair value category.

 

 

2024

 

 

2023

 

 

2022

 

(millions)

 

 

 

 

 

 

 

 

 

Balance at January 1,

 

$

176

 

 

$

251

 

 

$

148

 

Total realized and unrealized gains (losses):

 

 

 

 

 

 

 

 

 

Included in earnings:

 

 

 

 

 

 

 

 

 

Purchased power

 

 

3

 

 

 

6

 

 

 

77

 

Fuel used in electric generation

 

 

1

 

 

 

—

 

 

 

—

 

Gas purchased for resale

 

 

1

 

 

 

—

 

 

 

—

 

Included in regulatory assets/liabilities

 

 

115

 

 

 

(75

)

 

 

103

 

Settlements

 

 

(17

)

 

 

(6

)

 

 

(77

)

Purchases

 

 

91

 

 

 

—

 

 

 

—

 

Balance at December 31,

 

$

370

 

 

$

176

 

 

$

251

 
Schedule of Carrying Values and Estimated Fair Values of Debt Instruments For financial instruments that are not recorded at fair value, the carrying amounts and estimated fair values are as follows:

 

At December 31,

 

2024

 

 

2023

 

(millions)

 

Carrying
Amount

 

 

Estimated
Fair Value(1)

 

 

Carrying
Amount

 

 

Estimated
Fair Value(1)

 

Long-term debt(2)

 

$

4,220

 

 

$

4,142

 

 

$

4,219

 

 

$

4,301

 

Affiliated long-term debt(3)

 

 

230

 

 

 

230

 

 

 

230

 

 

 

230

 
(1)
Fair value is estimated using market prices, where available, and interest rates currently available for issuance of debt with similar terms and remaining maturities. All fair value measurements are classified as Level 2. The carrying amount of debt issuances with short-term maturities and variable rates refinanced at current market rates is a reasonable estimate of their fair value.
(2)
Carrying amount includes current portions, if any, included in securities due within one year and amounts which represent the unamortized debt issuance costs and discount or premium.
(3)
Carrying amount includes current portions presented in affiliated and related party payables, as applicable.
v3.25.0.1
Asset Retirement Obligations (Tables)
 12 Months Ended
Dec. 31, 2024
Asset Retirement Obligation Disclosure [Abstract]  
Schedule of Reconciliation of the Carrying Amount of AROs

A reconciliation of the beginning and ending aggregate carrying amount of AROs is as follows:

 

(millions)

 

2024

 

 

2023

 

Beginning balance

 

$

731

 

 

$

628

 

Liabilities incurred(1)

 

 

654

 

 

 

7

 

Liabilities settled

 

 

(79

)

 

 

(14

)

Accretion expense

 

 

46

 

 

 

29

 

Revisions in estimated cash flows(2)

 

 

(213

)

 

 

81

 

Ending balance

 

$

1,139

 

 

$

731

 
(1)
In 2024, primarily reflects AROs related to CCR remediation as discussed in Note 12.
(2)
In 2024, primarily reflects a revision related to CCR remediation costs as discussed in Note 12. In 2023, there was an increase in estimated costs associated with certain coal-fired generating units, including revisions following the approval of closure plans for a facility previously taken out of service.
v3.25.0.1
Employee Benefit Plans and Equity Compensation Plan (Tables)
 12 Months Ended
Dec. 31, 2024
Retirement Benefits [Abstract]  
Schedule of Changes in Projected Benefit Obligations

The measurement date used to determine pension and other postretirement benefit obligations is December 31. Data related to the changes in the projected benefit obligation for pension benefits and the accumulated benefit obligation for other postretirement benefits are presented below.

 

 

 

Pension Benefits

 

 

Other Postretirement Benefits

 

(millions)

 

2024

 

 

2023

 

 

2024

 

 

2023

 

Beginning balance

 

$

584

 

 

$

580

 

 

$

120

 

 

$

121

 

Service cost

 

 

8

 

 

 

8

 

 

 

1

 

 

 

1

 

Interest cost

 

 

31

 

 

 

33

 

 

 

8

 

 

 

8

 

Amendments

 

 

7

 

 

 

1

 

 

 

—

 

 

 

—

 

Actuarial (gain) loss

 

 

(10

)

 

 

1

 

 

 

(6

)

 

 

1

 

Benefits paid

 

 

(43

)

 

 

(39

)

 

 

(11

)

 

 

(11

)

Ending balance

 

$

577

 

 

$

584

 

 

$

112

 

 

$

120

 

 
Schedule of Assumptions Used to Determine Benefit Obligations

Significant assumptions used to determine the above benefit obligations are as follows:

 

 

 

Pension Benefits

 

 

Other Postretirement Benefits

 

 

 

2024

 

 

2023

 

 

2024

 

 

2023

 

Annual discount rate used to determine benefit obligation

 

 

5.84

%

 

 

5.39

%

 

 

5.86

%

 

 

5.42

%

Assumed annual rate of future salary increases for projected
   benefit obligation

 

 

3.47

%

 

 

3.54

%

 

N/A

 

 

N/A

 

Crediting interest rate for cash balance plans

 

 

4.59

%

 

 

4.14

%

 

N/A

 

 

N/A

 
Schedule of Net Funded Status

 

 

Pension Benefits

 

 

Other Postretirement Benefits

 

At December 31,

 

2024

 

 

2023

 

 

2024

 

 

2023

 

(millions)

 

 

 

 

 

 

 

 

 

 

 

 

Fair value of plan assets

 

$

603

 

 

$

588

 

 

$

—

 

 

$

—

 

Benefit obligation

 

 

577

 

 

 

584

 

 

 

112

 

 

 

120

 

Funded status

 

$

26

 

 

$

4

 

 

$

(112

)

 

$

(120

)

 
Schedule of Amounts Recognized in Balance Sheet

Amounts recognized on the consolidated balance sheets were as follows:

 

 

 

Pension Benefits

 

 

Other Postretirement Benefits

 

At December 31,

 

2024

 

 

2023

 

 

2024

 

 

2023

 

(millions)

 

 

 

 

 

 

 

 

 

 

 

 

Noncurrent assets

 

$

26

 

 

$

4

 

 

$

—

 

 

$

—

 

Current liability

 

 

—

 

 

 

—

 

 

 

(10

)

 

 

(11

)

Noncurrent liability

 

 

—

 

 

 

—

 

 

 

(102

)

 

 

(109

)
Schedule of Amounts Recognized in AOCI

Amounts recognized in AOCI were as follows:

 

 

 

Pension Benefits

 

 

Other Postretirement Benefits

 

At December 31,

 

2024

 

 

2023

 

 

2024

 

 

2023

 

(millions)

 

 

 

 

 

 

 

 

 

 

 

 

Net actuarial (gain) loss

 

$

2

 

 

$

2

 

 

$

(1

)

 

$

(1

)

 
Schedule of Amounts Recognized in Regulatory Assets

Amounts recognized in regulatory assets were as follows:

 

 

 

Pension Benefits

 

 

Other Postretirement Benefits

 

At December 31,

 

2024

 

 

2023

 

 

2024

 

 

2023

 

(millions)

 

 

 

 

 

 

 

 

 

 

 

 

Net actuarial (gain) loss

 

$

98

 

 

$

126

 

 

$

(43

)

 

$

(41

)

Prior service cost

 

 

7

 

 

 

1

 

 

 

—

 

 

 

—

 

Total

 

$

105

 

 

$

127

 

 

$

(43

)

 

$

(41

)

 
Schedule of Changes in Fair Value of Plan Assets

Changes in Fair Value of Plan Assets

 

 

 

Pension Benefits

 

At December 31,

 

2024

 

 

2023

 

(millions)

 

 

 

 

 

 

Beginning balance

 

$

588

 

 

$

561

 

Actual return (loss) on plan assets

 

 

50

 

 

 

66

 

Benefits paid

 

 

(43

)

 

 

(39

)

Contributions

 

 

8

 

 

 

—

 

Ending balance

 

$

603

 

 

$

588

 
Schedule of Fair Value Measurements By Category At December 31, 2024 and 2023, fair value measurements, and the level within the fair value hierarchy in which the measurements fall, were as follows:

 

At December 31,

 

2024

 

 

2023

 

(millions)

 

Level 1

 

 

Level 2

 

 

Level 3

 

 

Total

 

 

Level 1

 

 

Level 2

 

 

Level 3

 

 

Total

 

Cash and cash equivalents

 

$

294

 

 

$

—

 

 

$

—

 

 

$

294

 

 

$

4

 

 

$

1

 

 

$

—

 

 

$

5

 

Corporate debt instruments

 

 

—

 

 

 

—

 

 

 

—

 

 

 

—

 

 

 

—

 

 

 

137

 

 

 

—

 

 

 

137

 

Government and other debt
   instruments

 

 

—

 

 

 

—

 

 

 

—

 

 

 

—

 

 

 

—

 

 

 

14

 

 

 

—

 

 

 

14

 

Total recorded at fair value

 

$

294

 

 

$

—

 

 

$

—

 

 

$

294

 

 

$

4

 

 

$

152

 

 

$

—

 

 

$

156

 

Assets recorded at NAV(1)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Commingled funds/collective
   trust funds

 

 

 

 

 

 

 

 

 

 

 

—

 

 

 

 

 

 

 

 

 

 

 

 

436

 

Total recorded at NAV

 

 

 

 

 

 

 

 

 

 

$

—

 

 

 

 

 

 

 

 

 

 

 

$

436

 

Total investments(2)

 

 

 

 

 

 

 

 

 

 

$

294

 

 

 

 

 

 

 

 

 

 

 

$

592

 
(1)
These investments that are measured at fair value using the NAV per share (or its equivalent) as a practical expedient are not required to be categorized in the fair value hierarchy.
(2)
Excludes net assets related to pending sales of securities of $309 million at December 31, 2024. Excludes net assets related to pending sales of securities of $1 million, net accrued income of $1 million, and includes net assets related to pending purchases of securities of $6 million at December 31, 2023.
Schedule of Expected Benefit Payments

Expected Benefit Payments

 

(millions)

 

Pension Benefits

 

 

Other Postretirement Benefits

 

2025

 

$

50

 

 

$

11

 

2026

 

 

46

 

 

 

11

 

2027

 

 

45

 

 

 

11

 

2028

 

 

47

 

 

 

11

 

2029

 

 

46

 

 

 

11

 

2030 - 2034

 

 

240

 

 

 

54

 
Components of Net Periodic Benefit Cost

Components of Net Periodic Benefit (Credit) Cost

 

 

 

Pension Benefits

 

 

Other Postretirement Benefits

 

Year Ended December 31,

 

2024

 

 

2023

 

 

2022

 

 

2024

 

 

2023

 

 

2022

 

(millions)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Service cost

 

$

8

 

 

$

8

 

 

$

8

 

 

$

1

 

 

$

1

 

 

$

1

 

Interest cost

 

 

31

 

 

 

33

 

 

 

21

 

 

 

8

 

 

 

8

 

 

 

6

 

Expected return on assets

 

 

(37

)

 

 

(34

)

 

 

(49

)

 

 

—

 

 

 

—

 

 

 

—

 

Amortization of actuarial losses (gains)

 

 

9

 

 

 

12

 

 

 

1

 

 

 

(4

)

 

 

(4

)

 

 

—

 

Net periodic benefit (credit) cost

 

$

11

 

 

$

19

 

 

$

(19

)

 

$

5

 

 

$

5

 

 

$

7

 

 
Schedule of Defined Benefit Plan Amounts Recognized in Other Comprehensive Income (Loss)

Other changes in plan assets and benefit obligations recognized in other comprehensive income (net of tax) were as follows:

 

 

 

Pension Benefits

 

 

Other Postretirement Benefits

 

Year Ended December 31,

 

2024

 

 

2023

 

 

2022

 

 

2024

 

 

2023

 

 

2022

 

(millions)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Current year actuarial (gain) loss

 

$

—

 

 

$

(1

)

 

$

2

 

 

$

—

 

 

$

—

 

 

$

(1

)

Total recognized in other comprehensive income

 

$

—

 

 

$

(1

)

 

$

2

 

 

$

—

 

 

$

—

 

 

$

(1

)
Schedule of Defined Benefit Plan Amounts Recognized in Regulatory Assets

Other changes in plan assets and benefit obligations recognized in regulatory assets were as follows:

 

 

 

Pension Benefits

 

 

Other Postretirement Benefits

 

Year Ended December 31,

 

2024

 

 

2023

 

 

2022

 

 

2024

 

 

2023

 

 

2022

 

(millions)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Current year actuarial (gain) loss

 

$

(20

)

 

$

(27

)

 

$

95

 

 

$

(5

)

 

$

2

 

 

$

(41

)

Amortization of actuarial gain (loss)

 

 

(8

)

 

 

(11

)

 

 

(1

)

 

 

3

 

 

 

3

 

 

 

—

 

Current year prior service cost

 

 

6

 

 

 

1

 

 

 

—

 

 

 

—

 

 

 

—

 

 

 

—

 

Total recognized in regulatory assets

 

$

(22

)

 

$

(37

)

 

$

94

 

 

$

(2

)

 

$

5

 

 

$

(41

)
Schedule of Assumptions Used in Determining Net Periodic Benefit Cost

Significant assumptions used in determining net periodic benefit cost:

 

 

 

Pension Benefits

 

 

Other Postretirement Benefits

 

Year Ended December 31,

 

2024

 

 

2023

 

 

2022

 

 

2024

 

 

2023

 

 

2022

 

Discount rate

 

 

5.39

%

 

 

5.69

%

 

 

3.06

%

 

 

5.42

%

 

 

5.70

%

 

 

3.11

%

Expected return on plan assets

 

 

7.00

%

 

 

7.00

%

 

 

7.00

%

 

n/a

 

 

n/a

 

 

n/a

 

Rate of compensation increase

 

 

3.54

%

 

 

3.93

%

 

 

3.71

%

 

n/a

 

 

n/a

 

 

n/a

 

Crediting interest rate for cash balance plans

 

 

4.14

%

 

 

4.44

%

 

 

1.81

%

 

n/a

 

 

n/a

 

 

n/a

 

Health care cost trend rate

 

 

 

 

 

 

 

 

 

 

 

7.00

%

 

 

7.00

%

 

 

6.25

%

Ultimate health care cost trend rate

 

 

 

 

 

 

 

 

 

 

 

5.00

%

 

 

5.00

%

 

 

5.00

%

Year achieved

 

 

 

 

 

 

 

 

 

 

2031

 

 

2030

 

 

2026-2027

 
v3.25.0.1
Commitments and Contingencies (Tables)
 12 Months Ended
Dec. 31, 2024
Commitments and Contingencies Disclosure [Abstract]  
Schedule of Long-Term Purchase Agreements

At December 31, 2024, DESC had the following long-term commitments that are noncancelable or cancelable only under certain conditions, and that a third party that will provide the contracted goods or services has used to secure financing.

 

 

2025

 

 

2026

 

 

2027

 

 

2028

 

 

2029

 

 

Thereafter

 

 

Total

 

Purchased electric capacity(1)(2)

 

$

85

 

 

$

88

 

 

$

89

 

 

$

88

 

 

$

87

 

 

$

473

 

 

$

910

 

 

(1)
Includes affiliated amounts with certain solar facilities of $173 million.
(2)
Commitments represent estimated amounts payable for energy under power purchase contracts with qualifying facilities which expire at various dates through 2040. Energy payments are generally based on fixed dollar amounts per month and totaled $70 million in 2024, $70 million in 2023 and $75 million in 2022.
v3.25.0.1
Leases (Tables)
 12 Months Ended
Dec. 31, 2024
Leases [Abstract]  
Schedule of Lease Assets and Liabilities Recorded in Consolidated Balance Sheets

At December 31, 2024 and 2023, DESC had the following lease assets and liabilities recorded in the Consolidated Balance Sheets:

 

At December 31,

 

2024

 

 

2023

 

(millions)

 

 

 

 

 

 

Lease assets:

 

 

 

 

 

 

Operating lease assets(1)

 

$

20

 

 

$

18

 

Finance lease assets(2)

 

 

3

 

 

 

6

 

Total lease assets

 

$

23

 

 

$

24

 

Lease liabilities:

 

 

 

 

 

 

Operating lease - current(3)

 

$

3

 

 

$

2

 

Operating lease - noncurrent(4)

 

 

18

 

 

 

17

 

Finance lease - current(5)

 

 

2

 

 

 

3

 

Finance lease - noncurrent

 

 

2

 

 

 

4

 

Total lease liabilities

 

$

25

 

 

$

26

 

 

(1)
Included in other deferred debits and other assets in the Consolidated Balance Sheets.
(2)
Included in utility plant, net, in the Consolidated Balance Sheets, net of $15 million and $17 million of accumulated amortization at December 31, 2024 and December 31, 2023, respectively.
(3)
Included in other current liabilities in the Consolidated Balance Sheets.
(4)
Included in other deferred credits and other liabilities in the Consolidated Balance Sheets.
(5)
Included in securities due within one year in the Consolidated Balance Sheets.
Summary of Total Lease Cost

For the years ended December 31, 2024, 2023 and 2022, total lease cost consisted of the following:

 

Year Ended December 31,

 

2024

 

 

2023

 

 

2022

 

(millions)

 

 

 

 

 

 

 

 

 

Finance lease cost:

 

 

 

 

 

 

 

 

 

Amortization

 

$

3

 

 

$

3

 

 

$

4

 

Interest

 

 

—

 

 

 

—

 

 

 

1

 

Operating lease cost

 

 

4

 

 

 

5

 

 

 

4

 

Short-term lease cost

 

 

1

 

 

 

2

 

 

 

2

 

Total lease cost

 

$

8

 

 

$

10

 

 

$

11

 
Cash Paid for Amounts Included in Measurement of Lease Liabilities

For the years ended December 31, 2024, 2023 and 2022, cash paid for amounts included in the measurement of lease liabilities consisted of the following amounts, included in the Consolidated Statements of Cash Flows:

 

Year Ended December 31,

 

2024

 

 

2023

 

 

2022

 

(millions)

 

 

 

 

 

 

 

 

 

Operating cash flows from finance leases

 

$

—

 

 

$

—

 

 

$

1

 

Operating cash flows from operating leases

 

 

4

 

 

 

4

 

 

 

6

 

Financing cash flows from finance leases

 

 

3

 

 

 

4

 

 

 

4

 
Summary of Weighted-average Remaining Lease Term And Discount Rate for Operating and Finance Leases

At December 31, 2024 and 2023, the weighted-average remaining lease term and weighted-average discount rate for finance and operating leases were as follows:

 

At December 31,

 

2024

 

 

2023

 

Weighted-average remaining lease term - finance leases

 

3 years

 

 

3 years

 

Weighted-average remaining lease term - operating leases

 

16 years

 

 

18 years

 

Weighted-average discount rate - finance leases

 

 

3.17

%

 

 

2.96

%

Weighted-average discount rate - operating leases

 

 

4.34

%

 

 

4.12

%

 

 
Schedule of Maturity Analysis of Operating and Finance Lease Liabilities

Lease liabilities have the following scheduled maturities:

 

(millions)

 

Operating

 

 

Finance

 

2025

 

$

3

 

 

$

2

 

2026

 

 

3

 

 

 

1

 

2027

 

 

2

 

 

 

1

 

2028

 

 

2

 

 

 

—

 

2029

 

 

2

 

 

 

—

 

After 2029

 

 

20

 

 

 

—

 

Total undiscounted lease payments

 

 

32

 

 

 

4

 

Present value adjustment

 

 

(11

)

 

 

—

 

Present value of lease liabilities

 

$

21

 

 

$

4

 
v3.25.0.1
Operating Segments (Tables)
 12 Months Ended
Dec. 31, 2024
Segment Reporting [Abstract]  
Schedule of Segment Reporting Information, by Segment

The following table presents segment information pertaining to DESC’s operations:

Year Ended December 31,

 

Dominion Energy
South Carolina

 

 

Corporate
and Other

 

 

Consolidated
Total

 

(millions)

 

 

 

 

 

 

 

 

 

2024

 

 

 

 

 

 

 

 

 

Operating Revenue

 

$

3,173

 

 

$

—

 

 

$

3,173

 

Fuel used in electric generation(1)

 

 

603

 

 

 

—

 

 

 

603

 

Purchased power(1)

 

 

68

 

 

 

—

 

 

 

68

 

Gas purchased for resale(1)

 

 

245

 

 

 

—

 

 

 

245

 

Other operations and maintenance(1)(2)

 

 

658

 

 

 

59

 

 

 

717

 

Depreciation and amortization(1)

 

 

546

 

 

 

—

 

 

 

546

 

Other taxes(1)

 

 

300

 

 

 

—

 

 

 

300

 

Total Operating Expenses

 

 

2,420

 

 

 

59

 

 

 

2,479

 

Other income, net(3)

 

 

2

 

 

 

(3

)

 

 

(1

)

Interest charges, net of AFUDC(1)

 

 

276

 

 

 

—

 

 

 

276

 

Income tax expense (benefit)(1)

 

 

80

 

 

 

(15

)

 

 

65

 

Deferred cost of employee benefit plans, net of tax(3)

 

 

—

 

 

 

—

 

 

 

—

 

Comprehensive Income Attributable to Noncontrolling Interest(3)

 

 

23

 

 

 

—

 

 

 

23

 

Comprehensive Income (Loss) Available (Attributable) to
   Common Shareholder

 

 

376

 

 

 

(47

)

 

 

329

 

Capital expenditures

 

 

1,105

 

 

 

—

 

 

 

1,105

 

Total assets (billions)

 

 

17.0

 

 

 

—

 

 

 

17.0

 

 

 

 

 

 

 

 

 

 

2023

 

 

 

 

 

 

 

 

 

Operating Revenue

 

$

3,028

 

 

$

—

 

 

$

3,028

 

Fuel used in electric generation(1)

 

 

582

 

 

 

—

 

 

 

582

 

Purchased power(1)

 

 

72

 

 

 

—

 

 

 

72

 

Gas purchased for resale(1)

 

 

243

 

 

 

—

 

 

 

243

 

Other operations and maintenance(1)(2)

 

 

626

 

 

 

(24

)

 

 

602

 

Depreciation and amortization(1)

 

 

531

 

 

 

—

 

 

 

531

 

Other taxes(1)

 

 

292

 

 

 

—

 

 

 

292

 

Total Operating Expenses

 

 

2,346

 

 

 

(24

)

 

 

2,322

 

Other income, net(3)

 

 

24

 

 

 

—

 

 

 

24

 

Interest charges, net of AFUDC(1)

 

 

250

 

 

 

—

 

 

 

250

 

Income tax expense(1)

 

 

79

 

 

 

6

 

 

 

85

 

Deferred cost of employee benefit plans, net of tax(3)

 

 

1

 

 

 

—

 

 

 

1

 

Comprehensive Income Attributable to Noncontrolling Interest(3)

 

 

21

 

 

 

—

 

 

 

21

 

Comprehensive Income Available to Common Shareholder

 

 

357

 

 

 

18

 

 

 

375

 

Capital expenditures

 

 

957

 

 

 

—

 

 

 

957

 

Total assets (billions)

 

 

15.9

 

 

 

—

 

 

 

15.9

 

 

 

 

 

 

 

 

 

 

2022

 

 

 

 

 

 

 

 

 

Operating Revenue

 

$

3,783

 

 

$

—

 

 

$

3,783

 

Fuel used in electric generation(1)

 

 

1,000

 

 

 

—

 

 

 

1,000

 

Purchased power(1)

 

 

137

 

 

 

—

 

 

 

137

 

Gas purchased for resale(1)

 

 

433

 

 

 

—

 

 

 

433

 

Other operations and maintenance(1)(2)

 

 

626

 

 

 

4

 

 

 

630

 

Depreciation and amortization(1)

 

 

507

 

 

 

—

 

 

 

507

 

Other taxes(1)

 

 

277

 

 

 

—

 

 

 

277

 

Total Operating Expenses

 

 

2,980

 

 

 

4

 

 

 

2,984

 

Other income, net(3)

 

 

55

 

 

 

—

 

 

 

55

 

Interest charges, net of AFUDC(1)

 

 

220

 

 

 

—

 

 

 

220

 

Income tax expense (benefit)(1)

 

 

132

 

 

 

(1

)

 

 

131

 

Deferred cost of employee benefit plans, net of tax(3)

 

 

(1

)

 

 

—

 

 

 

(1

)

Comprehensive Income Attributable to Noncontrolling Interest(3)

 

 

20

 

 

 

—

 

 

 

20

 

Comprehensive Income (Loss) Available (Attributable) to
   Common Shareholder

 

 

485

 

 

 

(3

)

 

 

482

 

Capital expenditures

 

 

697

 

 

 

—

 

 

 

697

 

 

(1)
The significant expense categories and amounts in the segment information presented above align with the segment-level information that is regularly provided to DESC’s CODM.
(2)
Includes impairment of assets and other charges.
(3)
Items designated are other segment items for each reportable segment.
v3.25.0.1
Utility Plant and Nonutility Property (Tables)
 12 Months Ended
Dec. 31, 2024
Utility Plant And Non Utility Property [Abstract]  
Property, Plant and Equipment

Major classes of utility plant and other property and their respective balances at December 31, 2024 and 2023 were as follows:

 

At December 31,

 

2024

 

 

2023

 

(millions)

 

 

 

 

 

 

Gross utility plant:

 

 

 

 

 

 

Generation

 

$

6,635

 

 

$

6,322

 

Transmission

 

 

2,342

 

 

 

2,272

 

Distribution

 

 

6,311

 

 

 

5,901

 

Storage

 

 

79

 

 

 

79

 

General and other

 

 

651

 

 

 

644

 

Intangible

 

 

282

 

 

 

282

 

Construction work in progress

 

 

899

 

 

 

606

 

Nuclear fuel

 

 

570

 

 

 

609

 

Total gross utility plant

 

$

17,769

 

 

$

16,715

 

Gross nonutility property

 

$

16

 

 

$

25

 
Schedule of Jointly Owned Utility Plants

At December 31,

 

2024

 

2023

 

 

Summer Unit 1

 

Summer Unit 1

Percent owned

 

66.7%

 

66.7%

Plant in service

 

$

1.6

 

billion

 

$

1.6

 

billion

Accumulated depreciation

 

$

784

 

million

 

$

772

 

million

Construction work in progress

 

$

58

 

million

 

$

88

 

million
v3.25.0.1
Affiliated and Related Party Transactions (Tables)
 12 Months Ended
Dec. 31, 2024
Related Party Transactions [Abstract]  
Schedule of Affiliated Transactions

DESC transacts with affiliates for certain quantities of electricity in the ordinary course of business. DESC also enters into certain commodity derivative contracts with affiliates. DESC uses these contracts, which are principally comprised of forward commodity purchases, to manage commodity price risks associated with purchases of electricity. See Note 8 for more information.

 

Year Ended December 31,

 

2024

 

 

2023

 

 

2022

 

(millions)

 

 

 

 

 

 

 

 

 

Direct and allocated costs from DES(1)

 

$

222

 

 

$

222

 

 

$

212

 

Operating Revenues – Electric from sales to affiliate

 

 

7

 

 

 

4

 

 

 

4

 

Operating Revenues – Gas from sales to affiliate

 

 

1

 

 

 

1

 

 

 

1

 

Operating Expenses – Other taxes from affiliate

 

 

8

 

 

 

8

 

 

 

8

 

Purchases of electricity from solar affiliates

 

 

8

 

 

 

13

 

 

 

14

 

 

(1)
Includes capitalized expenditures of $57 million, $59 million and $48 million for the years ended December 31, 2024, 2023 and 2022, respectively.
Schedule of Affiliated Transactions

At December 31,

 

2024

 

 

2023

 

(millions)

 

 

 

 

 

 

Payable to DES

 

 

19

 

 

 

18

 

Payable to SCANA Corporation

 

 

7

 

 

 

7

 

Payable to PSNC

 

 

 

 

 

13

 

Derivative assets with affiliates(1)

 

 

48

 

 

 

33

 

 

(1)
Includes amounts recorded in current derivative assets of $4 million and $2 million as of December 31, 2024 and 2023, respectively, and amounts recorded in noncurrent derivative assets of $44 million and $31 million as of December 31, 2024 and 2023, respectively.
v3.25.0.1
Other Income (Expense), Net (Tables)
 12 Months Ended
Dec. 31, 2024
Income Statement [Abstract]  
Components of Other Income (Expense), Net

Components of other income (expense), net are as follows:

 

Year Ended December 31,

 

2024

 

 

2023

 

 

2022

 

(millions)

 

 

 

 

 

 

 

 

 

Other income

 

$

12

 

 

$

8

 

 

$

10

 

Gains on sales of assets(1)

 

 

4

 

 

 

32

 

 

 

42

 

Other expense

 

 

(19

)

 

 

(16

)

 

 

2

 

Allowance for equity funds used during construction

 

 

2

 

 

 

—

 

 

 

1

 

Other income (expense), net

 

$

(1

)

 

$

24

 

 

$

55

 
(1)
Includes amounts recognized in connection with the transfer of property, plant and equipment to satisfy litigation in 2023 and 2022. See Note 12 for additional information.
v3.25.0.1
Nature of Operations (Narrative) (Detail)
 12 Months Ended
Dec. 31, 2024
Segment
Organization, Consolidation and Presentation of Financial Statements [Abstract]  
Number of primary operating segments 1
v3.25.0.1
Summary of Significant Accounting Policies (Narrative) (Detail)
$ in Millions
 3 Months Ended 4 Months Ended 5 Months Ended 12 Months Ended
Sep. 30, 2021
USD ($)
Dec. 31, 2024
USD ($)
MW
Dec. 31, 2024
USD ($)
MW
Dec. 31, 2024
USD ($)
MW
Dec. 31, 2023
USD ($)
Dec. 31, 2022
USD ($)
Dec. 31, 2021
USD ($)
Significant Accounting Policies              
Public utilities, allowance for funds used during construction, rate       5.30% 5.30% 2.70%  
Utilities operating expense, maintenance and operations       $ 492 $ 436 $ 460  
Turbine maintenance expense       16 20 20  
Amount accrued annually for nuclear fuel outages   $ 24 $ 17        
Nuclear refueling outage cost       42 26 1  
Amount accrued annually for tree trimming and vegetation management   34 28        
Tree trimming and vegetation management cost       29 31 33  
Decommissioning liability, noncurrent   831 831 831      
Payments to acquire investments to be held in decommissioning trust fund       3      
Unbilled revenues   176 176 176 176    
Unrecognized tax benefits   38 38 38 62 $ 68 $ 62
Interest expense       12      
Income taxes related to affiliated payable       12 15    
Margin liabilities with cash collateral   0 0 0 0    
Margin assets with cash collateral   $ 0 $ 0 $ 0 $ 0    
Option to extend, existence, operating lease       true      
Maximum [Member]              
Significant Accounting Policies              
Lease renewal term   70 years 70 years 70 years      
Original term of leases   1 year 1 year 1 year      
Minimum [Member]              
Significant Accounting Policies              
Lease renewal term   1 year 1 year 1 year      
Accounts Receivable [Member] | Credit Concentration Risk [Member] | Residential Commercial And Industrial Customers [Member]              
Significant Accounting Policies              
Concentration risk percentage       7.00%      
Turbine [Member]              
Significant Accounting Policies              
Utilities operating expense, maintenance and operations $ 25            
GENCO [Member]              
Significant Accounting Policies              
Power Generation Capacity Megawatts | MW   605 605 605      
v3.25.0.1
Summary of Significant Accounting Policies (Schedule of Weighted Average Depreciation Rates) (Detail)
 12 Months Ended
Dec. 31, 2024
Dec. 31, 2023
Dec. 31, 2022
Generation [Member]      
Composite weighted average depreciation rates for utility plant 2.33% 2.33% 2.34%
Transmission [Member]      
Composite weighted average depreciation rates for utility plant 2.53% 2.54% 2.36%
Distribution [Member]      
Composite weighted average depreciation rates for utility plant 2.53% 2.57% 2.59%
Storage [Member]      
Composite weighted average depreciation rates for utility plant 2.75% 2.83% 2.93%
General and other [Member]      
Composite weighted average depreciation rates for utility plant 3.15% 3.16% 3.35%
v3.25.0.1
Summary of Significant Accounting Policies (Schedule of Cash and Cash equivalents) (Details) - USD ($)
$ in Millions
Dec. 31, 2024
Dec. 31, 2023
Dec. 31, 2022
Dec. 31, 2021
Accounting Policies [Abstract]        
Cash and cash equivalents $ 0 $ 1 $ 11 $ 30
Restricted cash and equivalents [1] 0 0 0 24
Cash, restricted cash and equivalents shown in the Consolidated Statements of Cash Flows $ 0 $ 1 $ 11 $ 54
[1] Restricted cash and equivalent balances are presented within other current assets on the Consolidated Balance Sheets.
v3.25.0.1
Rate and Other Regulatory Matters (Narrative) (Detail)
$ in Millions
 1 Months Ended 3 Months Ended 8 Months Ended 12 Months Ended
Feb. 27, 2025
USD ($)
Jan. 31, 2025
USD ($)
Dec. 31, 2024
USD ($)
mi
kV
Oct. 31, 2024
USD ($)
Sep. 30, 2024
USD ($)
Jul. 31, 2024
USD ($)
Jun. 30, 2024
USD ($)
Mar. 31, 2024
USD ($)
mi
kV
Feb. 29, 2024
USD ($)
Jan. 31, 2024
USD ($)
Sep. 30, 2024
USD ($)
Aug. 31, 2024
Dec. 31, 2024
USD ($)
Dec. 31, 2023
USD ($)
Dec. 31, 2022
USD ($)
Rate And Other Regulatory Matters [Line Items]                              
Impairment of assets                         $ 60 $ 3 $ 6
Other income (expense), net [1]                         $ (1) 24 55
Miles of Lines | mi     17         7              
Type of Line | kV     230         230              
Estimated electric transmission project cost     $ 55         $ 40              
Regulatory asset recovery assessment end period                         2078    
Impairment of assets and other charges                         $ 60 3 4
Dominion Energy South Carolina, Inc. [Member]                              
Rate And Other Regulatory Matters [Line Items]                              
Storm restoration expected recovery period                       2034      
Storm restoration expected recovery         $ 2                    
Electric Base Rate Case [Member]                              
Rate And Other Regulatory Matters [Line Items]                              
Amount of Increase in proposed non fuel base rate               295              
Decrease in storm damage and DSM components               4              
Increase in proposed base rate amount               $ 291              
Increase in proposed base rate percentage               12.59%              
Percentage of current authorized earned ROE               9.50%              
Percentage of earned return on equity               4.32%              
Percentage of earned return on equity proposed rate               10.60%              
Electric Base Rate Case [Member] | Comprehensive Settlement Agreement [Member]                              
Rate And Other Regulatory Matters [Line Items]                              
Increase in non-fuel base rate amount           $ 219                  
Percentage of authorized ROE           9.94%                  
One-time bill credit to residential customers           $ 7                  
Electric - Cost of Fuel [Member]                              
Rate And Other Regulatory Matters [Line Items]                              
Proposed South Carolina Commission Order for Decrease of Total Fuel Cost Component of Retail Electric Rates to produce a projected under-recovery                 $ 315            
South Carolina Commission Order for Increase/Decrease of Total Fuel Cost Component of Retail Electric Rates to produce a projected under-recovery               $ 316              
Electric - Cost of Fuel [Member] | Subsequent Event [Member]                              
Rate And Other Regulatory Matters [Line Items]                              
Proposed South Carolina Commission Order for Increase of Total Fuel Cost Component of Retail Electric Rates to produce a projected under-recovery $ 154                            
Natural Gas Rates [Member]                              
Rate And Other Regulatory Matters [Line Items]                              
Public utilities, total revenue requirement amount             $ 523                
Amount of increase in base rate       $ 13     $ 13                
Reserve For Refunds To Electric Utility Customers [Member]                              
Rate And Other Regulatory Matters [Line Items]                              
Electric service customers recovery period                         11 years    
Corporate and Other                              
Rate And Other Regulatory Matters [Line Items]                              
Other income (expense), net [1]                         $ (3) $ 0 $ 0
Corporate and Other | Electric Base Rate Case [Member]                              
Rate And Other Regulatory Matters [Line Items]                              
Impairment of assets                     $ 58        
Impairment of assets after tax                     44        
Write down certain materials and supplies inventory                     50        
Other income (expense), net                     3        
Impairment of assets and other charges                     $ 55        
Deferred Losses or Gains On Interest Rate Derivatives [Member]                              
Rate And Other Regulatory Matters [Line Items]                              
Changes in fair value and payments of interest rate derivatives designated as cash flow hedge, amortized to interest expense, year                         2065    
Monetization Of Guaranty Settlement [Member]                              
Rate And Other Regulatory Matters [Line Items]                              
Electric service customers recovery period                         20 years    
End period for recovery                         Dec. 31, 2039    
Income Taxes Refundable Through Future Rates [Member]                              
Rate And Other Regulatory Matters [Line Items]                              
Remaining lives of related property period                         85 years    
NND Project Costs [Member]                              
Rate And Other Regulatory Matters [Line Items]                              
Electric service customers recovery period                         20 years    
End period for recovery                         Dec. 31, 2039    
Deferred Employee Benefit Plan Costs [Member]                              
Rate And Other Regulatory Matters [Line Items]                              
Regulatory asset recovery assessment end period                         2044    
Average service period expected to recover other deferred benefit costs                         11 years    
Other Unrecovered Plant [Member]                              
Rate And Other Regulatory Matters [Line Items]                              
Amortization of carrying value of coal-fired generating unit                         2025    
New expected amortization of carrying value of coal-fired generating unit                         2039    
Advanced Metering Infrastructure Project [Member]                              
Rate And Other Regulatory Matters [Line Items]                              
New expected amortization of carrying value of coal-fired generating unit                         2028    
Demand Side Management Programs [Member]                              
Rate And Other Regulatory Matters [Line Items]                              
Recovery period of regulatory asset     3 years                   3 years    
Asset Retirement Obligation Costs [Member]                              
Rate And Other Regulatory Matters [Line Items]                              
Recovery period of regulatory asset     105 years                   105 years    
Environmental Remediation Costs [Member]                              
Rate And Other Regulatory Matters [Line Items]                              
Recovery period of regulatory asset     24 years                   24 years    
Deferred Transmission Operating Costs [Member]                              
Rate And Other Regulatory Matters [Line Items]                              
Deferred transmission operating costs expected recovery period                         2062    
Rider DSM [Member] | Electric - Other [Member]                              
Rate And Other Regulatory Matters [Line Items]                              
South Carolina Commission Order, Annual DSM Program Rate Rider Recovery Amount                   $ 47          
Rider DSM [Member] | Electric - Other [Member] | Subsequent Event [Member]                              
Rate And Other Regulatory Matters [Line Items]                              
South Carolina Commission Order, Annual DSM Program Rate Rider Recovery Amount   $ 46                          
South Carolina Commission [Member] | Electric - Other [Member]                              
Rate And Other Regulatory Matters [Line Items]                              
Annual increase (decrease) in pension cost rider                 $ 9            
South Carolina Commission [Member] | Electric - Other [Member] | Subsequent Event [Member]                              
Rate And Other Regulatory Matters [Line Items]                              
Annual increase (decrease) in pension cost rider $ (13)                            
[1] Items designated are other segment items for each reportable segment.
v3.25.0.1
Rate and Other Regulatory Matters (Schedule of Regulatory Assets) (Detail) - USD ($)
$ in Millions
Dec. 31, 2024
Dec. 31, 2023
Regulatory Assets    
Regulatory assets, current $ 299 $ 444
Regulatory assets, noncurrent 3,342 3,107
Total regulatory assets 3,641 3,551
NND Project Costs [Member]    
Regulatory Assets    
Regulatory assets, current [1] 138 138
Regulatory assets, noncurrent [1] 1,811 1,949
Deferred Employee Benefit Plan Costs [Member]    
Regulatory Assets    
Regulatory assets, current [2] 8 11
Regulatory assets, noncurrent [2] 94 118
Interest Rate Hedges [Member]    
Regulatory Assets    
Regulatory assets, noncurrent [3] 167 168
Other Unrecovered Plant [Member]    
Regulatory Assets    
Regulatory assets, current [4] 18 19
Regulatory assets, noncurrent [4] 89 66
Demand Side Management Programs [Member]    
Regulatory Assets    
Regulatory assets, current [5] 24 22
Regulatory assets, noncurrent [5] 49 46
Asset Retirement Obligation Costs [Member]    
Regulatory Assets    
Regulatory assets, current [6] 8 44
Regulatory assets, noncurrent [6] 695 379
Cost of Fuel and Purchased Gas Under-Collections [Member]    
Regulatory Assets    
Regulatory assets, current [7] 35 154
Other Regulatory Assets [Member]    
Regulatory Assets    
Regulatory assets, current [8] 13 6
Regulatory assets, noncurrent [8] 152 130
Environmental Remediation Costs [Member]    
Regulatory Assets    
Regulatory assets, noncurrent [9] 42 34
Deferred Storm Damage Costs [Member]    
Regulatory Assets    
Regulatory assets, noncurrent [10] 76 40
Deferred Transmission Operating Costs [Member]    
Regulatory Assets    
Regulatory assets, noncurrent [11] 72 74
Derivatives [Member]    
Regulatory Assets    
Regulatory assets, noncurrent [12] $ 95 $ 103
[1] Reflects expenditures associated with the NND Project, which pursuant to the SCANA Merger Approval Order, will be recovered from electric service customers over a 20-year period ending in 2039.
[2] Employee benefit plan costs have historically been recovered as they have been recorded under GAAP. Deferred employee benefit plan costs represent amounts of pension and other postretirement benefit costs which were accrued as liabilities and treated as regulatory assets pursuant to FERC guidance, and costs deferred pursuant to specific South Carolina Commission regulatory orders. DESC expects to recover deferred pension costs through utility rates over periods through 2044. DESC expects to recover other deferred benefit costs through utility rates, primarily over average service periods of participating employees up to 11 years.
[3] Represents settled interest rate derivatives designated as cash flow hedges expected to be amortized to interest expense over the lives of the underlying debt through 2065.
[4] Represents the carrying value of coal-fired generating units, including related materials and supplies inventory, retired from service prior to being fully depreciated. DESC is amortizing these amounts through cost of service rates following depreciation amounts that were designed to recover the retired units cost over their previous estimated remaining useful lives, which has been estimated to be through 2025. Based on current projections of remaining decommissioning costs, projected recovery is expected to extend through 2039. In addition, amounts include unrecovered costs of existing meters and equipment retired from service prior to being fully depreciated as part of the Advanced Metering Infrastructure project, which are being recovered through rates through 2028. This amount also includes certain inventory and preliminary survey and investigation charges being amortized through 2026 related to the transition or conversion from coal to gas fired generation at certain facilities.
[5] epresents deferred costs associated with electric demand reduction programs, and such deferred costs are currently being recovered over three years through an approved rate rider.
[6] Represents uncollected costs, including deferred depreciation and accretion expense, related to legal obligations associated with the future retirement of generation, transmission and distribution properties. The AROs primarily relate to DESC’s electric generating facilities, including Summer, and are expected to be recovered over the related property lives and periods of decommissioning which may range up to approximately 105 years. In addition, the balance at December 31, 2024 reflects amounts related to the EPA’s May 2024 final rule concerning CCR as discussed in Note 12.
[7] Represents amounts under- or over-collected from customers pursuant to the cost of fuel and purchased gas components approved by the South Carolina Commission.
[8] Various other regulatory assets are expected to be recovered through rates over varying periods through 2078.
[9] Reflects amounts associated with the assessment and clean-up of sites currently or formerly owned by DESC. Such remediation costs are expected to be recovered over periods of up to 24 years. See Note 12 for additional information.
[10] Unamortized amounts are included in rate base and are earning a current return.
[11] Includes deferred depreciation and property taxes associated with certain transmission assets for which DESC expects future recovery from customers through 2062. Unamortized amounts are included in rate base and earning a current return.
[12] Represents changes in the fair value of derivatives, excluding separately presented interest rate hedges, that following settlement are expected to be recovered from or refunded to customers.
v3.25.0.1
Rate and Other Regulatory Matters (Schedule of Regulatory Liabilities) (Detail) - USD ($)
$ in Millions
Dec. 31, 2024
Dec. 31, 2023
Regulatory Liabilities    
Regulatory liability, current $ 201 $ 205
Regulatory liability, noncurrent 2,488 2,579
Total regulatory liabilities 2,689 2,784
Monetization Of Guaranty Settlement [Member]    
Regulatory Liabilities    
Regulatory liability, current [1] 67 67
Regulatory liability, noncurrent [1] 568 635
Income Taxes Refundable Through Future Rates [Member]    
Regulatory Liabilities    
Regulatory liability, current [2] 24 37
Regulatory liability, noncurrent [2] 820 839
Asset Removal Costs [Member]    
Regulatory Liabilities    
Regulatory liability, noncurrent [3] 598 633
Reserve For Refunds To Electric Utility Customers [Member]    
Regulatory Liabilities    
Regulatory liability, current [4] 73 83
Regulatory liability, noncurrent [4] 161 237
Derivatives [Member]    
Regulatory Liabilities    
Regulatory liability, current [5] 328 229
Regulatory liability, noncurrent [5] 27 12
Other Regulatory Liability [Member]    
Regulatory Liabilities    
Regulatory liability, current 68 56
Regulatory liability, noncurrent $ 10 $ 6
[1] Represents proceeds related to the monetization of the Toshiba Settlement. In accordance with the SCANA Merger Approval Order, this balance, net of amounts that may be required to satisfy liens, will be refunded to electric customers over a 20-year period ending in 2039.
[2] Includes (i) excess deferred income taxes arising from the remeasurement of deferred income taxes in connection with the enactment of the 2017 Tax Reform Act (certain of which are protected under normalization rules and will be amortized over the remaining lives of related property, and certain of which will be amortized to the benefit of customers over prescribed periods as instructed by regulators) and (ii) deferred income taxes arising from investment tax credits, offset by (iii) deferred income taxes that arise from utility operations that have not been included in customer rates (a portion of which relate to depreciation and are expected to be recovered over the remaining lives of the related property which may range up to 85 years). See Note 7 for additional information.
[3] Represents estimated net collections through depreciation rates of amounts to be expended for the removal of assets in the future.
[4] Reflects amounts previously collected from retail electric customers of DESC for the NND Project to be credited to customers over an estimated 11-year period effective February 2019 in connection with the SCANA Merger Approval Order.
[5] Represents changes in the fair value of derivatives, excluding separately presented interest rate hedges, that following settlement are expected to be recovered from or refunded to customers.
v3.25.0.1
Operating Revenue (Disaggregation of Revenue) (Detail) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2024
Dec. 31, 2023
Dec. 31, 2022
Total Operating Revenues [1] $ 3,173 $ 3,028 $ 3,783
Electric Operations      
Operating revenue from contracts with customers 2,626 2,502 3,079
Other revenues 25 27 27
Total Operating Revenues 2,651 2,529 3,106
Gas Distribution      
Operating revenue from contracts with customers 521 498 676
Other revenues 1 1 1
Total Operating Revenues 522 499 677
Residential | Electric Operations      
Operating revenue from contracts with customers 1,259 1,160 1,375
Residential | Gas Distribution      
Operating revenue from contracts with customers 302 268 303
Commercial | Electric Operations      
Operating revenue from contracts with customers 855 820 968
Commercial | Gas Distribution      
Operating revenue from contracts with customers 126 129 184
Industrial | Electric Operations      
Operating revenue from contracts with customers 389 372 533
Industrial | Gas Distribution      
Operating revenue from contracts with customers 68 77 166
Other | Electric Operations      
Operating revenue from contracts with customers 123 150 203
Other | Gas Distribution      
Operating revenue from contracts with customers $ 25 $ 24 $ 23
[1] See Note 16 for amounts attributable to affiliates.
v3.25.0.1
Operating Revenue (Narrative) (Detail) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2024
Dec. 31, 2023
Disaggregation Of Revenue [Line Items]    
Contract liability balances $ 6 $ 7
Revenue recognized from contract liability balances $ 5 $ 9
Minimum [Member]    
Disaggregation Of Revenue [Line Items]    
Service Contract, Term 10 years  
Maximum [Member]    
Disaggregation Of Revenue [Line Items]    
Service Contract, Term 15 years  
v3.25.0.1
Operating Revenue (Balance and Activity Related to Contract Costs Deferred as Regulatory Assets) (Detail) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2024
Dec. 31, 2023
Revenues [Abstract]    
Beginning balance $ 11 $ 9
Additional costs 0 3
Amortization (1) (1)
Ending balance $ 10 $ 11
v3.25.0.1
Equity (Narrative) (Detail) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2022
Dec. 31, 2024
Dec. 31, 2023
Class Of Stock [Line Items]      
Common stock, par value  
Common stock, shares authorized   50,000,000 50,000,000
Common stock, shares issued   40,300,000 40,300,000
Common stock, shares outstanding   40,300,000 40,300,000
Preferred stock, par value  
Preferred stock, shares authorized   20,000,000 20,000,000
Preferred stock, shares issued   1,000 1,000
Preferred stock, shares outstanding   1,000 1,000
Dominion Energy | SCDOR | Common Stock      
Class Of Stock [Line Items]      
Common stock issued to satisfy the settlement $ 72    
v3.25.0.1
Long-Term and Short-Term Debt (Schedule of Debt) (Detail) - USD ($)
$ in Millions
Dec. 31, 2024
Dec. 31, 2023
Debt Instrument [Line Items]    
Total principal $ 4,487 $ 4,487
Affiliated and related party payables 0 (230)
Unamortized discount, premium and debt issuance costs, net (37) (38)
Finance leases 4  
Total long-term debt 4,452 4,223
First Mortgage Bonds    
Debt Instrument [Line Items]    
Total principal $ 4,134  
First Mortgage Bonds | DESC    
Debt Instrument [Line Items]    
Weighted-average coupon rate [1] 5.23%  
Total principal $ 4,134 4,134
Tax Exempt Financings Variable Rate Due 2038 | DESC    
Debt Instrument [Line Items]    
Weighted-average coupon rate [1],[2] 3.70%  
Total principal [2] $ 35 35
Tax Exempt Financings Variable Rate Due 2038 | Genco    
Debt Instrument [Line Items]    
Weighted-average coupon rate [1] 3.70%  
Total principal $ 33 33
Tax Exempt Financings 3.625% and 4.00% Due 2028 and 2033 | DESC    
Debt Instrument [Line Items]    
Weighted-average coupon rate [1],[2] 3.90%  
Total principal [2] $ 54 54
Other Debt    
Debt Instrument [Line Items]    
Total principal $ 231  
Other Debt | DESC    
Debt Instrument [Line Items]    
Weighted-average coupon rate [1],[2] 3.58%  
Total principal [2] $ 1 1
5.31% Affiliated Note Due 2027 | Genco    
Debt Instrument [Line Items]    
Weighted-average coupon rate [1] 5.31%  
Total principal $ 230 230
Finance Lease    
Debt Instrument [Line Items]    
Finance leases $ 2 $ 4
[1] Represents weighted-average coupon rates for debt outstanding as of December 31, 2024
[2] Industrial revenue bonds totaling $68 million are secured by letters of credit that expire, subject to renewal, in the fourth quarter of 2025.
v3.25.0.1
Long-Term and Short-Term Debt (Schedule of Debt) (Parenthetical) (Detail)
$ in Millions
 12 Months Ended
Dec. 31, 2024
USD ($)
Letter of Credit  
Debt Instrument [Line Items]  
Debt instrument, face amount $ 68
First Mortgage Bonds | Minimum [Member] | DESC  
Debt Instrument [Line Items]  
Debt Instrument, Maturity Year 2028
Debt instrument, interest rate 2.30%
First Mortgage Bonds | Maximum [Member] | DESC  
Debt Instrument [Line Items]  
Debt Instrument, Maturity Year 2065
Debt instrument, interest rate 6.625%
Tax Exempt Financings Variable Rate Due 2038 | DESC  
Debt Instrument [Line Items]  
Debt Instrument, Maturity Year 2038
Tax Exempt Financings Variable Rate Due 2038 | Genco  
Debt Instrument [Line Items]  
Debt Instrument, Maturity Year 2038
Tax Exempt Financings 3.625% and 4.00% Due 2028 and 2033 | Minimum [Member] | DESC  
Debt Instrument [Line Items]  
Debt Instrument, Maturity Year 2028
Debt instrument, interest rate 3.625%
Tax Exempt Financings 3.625% and 4.00% Due 2028 and 2033 | Maximum [Member] | DESC  
Debt Instrument [Line Items]  
Debt Instrument, Maturity Year 2033
Debt instrument, interest rate 4.00%
5.31% Affiliated Note Due 2027 | Genco  
Debt Instrument [Line Items]  
Debt Instrument, Maturity Year 2027
Debt instrument, interest rate 5.31%
v3.25.0.1
Long-Term and Short-Term Debt (Schedule of Principal Payments of Long-Term Debt) (Detail) - USD ($)
$ in Millions
Dec. 31, 2024
Dec. 31, 2023
Debt Instrument [Line Items]    
2025 $ 0  
2026 0  
2027 230  
2028 92  
2029 0  
Thereafter 4,165  
Total $ 4,487 $ 4,487
Weighted-average coupon, 2027 5.31%  
Weighted-average coupon, 2028 4.14%  
Weighted-average coupon, Thereafter 5.21%  
First Mortgage Bonds    
Debt Instrument [Line Items]    
2025 $ 0  
2026 0  
2027 0  
2028 53  
2029 0  
Thereafter 4,081  
Total 4,134  
Tax Exempt Financings    
Debt Instrument [Line Items]    
2025 0  
2026 0  
2027 0  
2028 39  
2029 0  
Thereafter 83  
Total 122  
Other Debt    
Debt Instrument [Line Items]    
2025 0  
2026 0  
2027 230  
2028 0  
2029 0  
Thereafter 1  
Total $ 231  
v3.25.0.1
Long-Term and Short-Term Debt (Narrative) (Detail)
 1 Months Ended 12 Months Ended
Jan. 31, 2025
USD ($)
May 31, 2024
Mar. 31, 2023
USD ($)
Dec. 31, 2024
USD ($)
Dec. 31, 2023
USD ($)
Dec. 31, 2022
USD ($)
Apr. 30, 2024
Debt Instrument [Line Items]              
Unfunded property additions       70.00%      
Consecutive months for bond ratio       12 months      
Months preceding issuance of bonds       18 months      
Bonds Ratio       5      
Commercial paper borrowing limit     $ 2,200,000,000        
Affiliated and related party payables and other       $ 194,000,000 $ 163,000,000    
Interest charges/expense from money pool transactions [1]       276,000,000 250,000,000 $ 220,000,000  
Subsequent Event [Member]              
Debt Instrument [Line Items]              
Commercial paper borrowing limit $ 1,800,000,000            
Short term commercial paper maturity period 2 years            
Maximum [Member]              
Debt Instrument [Line Items]              
Short term commercial paper maturity period     1 year        
Dominion Energy              
Debt Instrument [Line Items]              
Facility limit       6,000,000,000      
Inter company credit facility maximum capacity       900,000,000      
Affiliated and related party payables and other       942,000,000 442,000,000    
Interest charges/expense from money pool transactions       50,000,000 53,000,000 $ 19,000,000  
Joint Revolving Credit Facility              
Debt Instrument [Line Items]              
Facility limit [2]       1,000,000,000 [3] $ 1,000,000,000    
Joint Revolving Credit Facility | Commercial Paper              
Debt Instrument [Line Items]              
Debt instrument, face amount       250,000,000      
Industrial Revenue Bonds              
Debt Instrument [Line Items]              
Debt instrument, face amount       68,000,000      
Intercompany Credit Facility              
Debt Instrument [Line Items]              
Line of credit, outstanding       597,000,000      
Genco              
Debt Instrument [Line Items]              
Commercial paper borrowing limit     $ 200,000,000        
Genco | Subsequent Event [Member]              
Debt Instrument [Line Items]              
Commercial paper borrowing limit $ 300,000,000            
Short term commercial paper maturity period 2 years            
Genco | 5.31% Promissory Note due in May 2027              
Debt Instrument [Line Items]              
Debt instrument, face amount       230,000,000      
Interest rate percentage   5.31%         3.05%
Debt instrument, maturity date   2024-05          
Debt instrument extended maturity date   2027-05          
Genco | Maximum [Member]              
Debt Instrument [Line Items]              
Short term commercial paper maturity period     1 year        
Genco | Dominion Energy              
Debt Instrument [Line Items]              
Inter company credit facility maximum capacity       200,000,000      
Genco | Intercompany Credit Facility              
Debt Instrument [Line Items]              
Line of credit, outstanding       62,000,000      
DESC | First Mortgage Bonds [Member] | Subsequent Event [Member]              
Debt Instrument [Line Items]              
Debt instrument, face amount $ 450,000,000            
Interest rate percentage 5.30%            
Debt Instrument Maturity Year 2035            
Fuel company | Dominion Energy              
Debt Instrument [Line Items]              
Inter company credit facility maximum capacity       $ 400,000,000      
[1] See Note 16 for amounts attributable to affiliates.
[2] A maximum of $1.0 billion of the facility is available to DESC, assuming adequate capacity is available after giving effect to uses by co-borrowers Dominion Energy and Virginia Power. A sub-limit for DESC is set within the facility limit but can be changed at the option of the co-borrowers multiple times per year. At December 31, 2024, the sub-limit for DESC was $500 million. If DESC has liquidity needs in excess of its sub-limit, the sub-limit may be changed or such needs may be satisfied through short-term borrowings from Dominion Energy. This credit facility matures in June 2026, with the potential to be extended by the borrowers to June 2028. The credit facility can be used to support bank borrowings and the issuance of commercial paper, as well as to support up to $1.0 billion (or the sub-limit, whichever is less) of letters of credit.
[3] In May 2024, the joint revolving credit facility was amended to remove Questar Gas as a co-borrower.
v3.25.0.1
Long-Term and Short-Term Debt (Schedule of Line of Credit Facilities) (Detail) - Joint Revolving Credit Facility - USD ($)
Dec. 31, 2024
 [2]
Dec. 31, 2023
Debt Instrument [Line Items]    
Facility limit [1] $ 1,000,000,000 $ 1,000,000,000
Outstanding Commercial Paper [1],[3] 250,000,000 254,000,000
Outstanding Letters of Credit [1] $ 0 $ 0
[1] A maximum of $1.0 billion of the facility is available to DESC, assuming adequate capacity is available after giving effect to uses by co-borrowers Dominion Energy and Virginia Power. A sub-limit for DESC is set within the facility limit but can be changed at the option of the co-borrowers multiple times per year. At December 31, 2024, the sub-limit for DESC was $500 million. If DESC has liquidity needs in excess of its sub-limit, the sub-limit may be changed or such needs may be satisfied through short-term borrowings from Dominion Energy. This credit facility matures in June 2026, with the potential to be extended by the borrowers to June 2028. The credit facility can be used to support bank borrowings and the issuance of commercial paper, as well as to support up to $1.0 billion (or the sub-limit, whichever is less) of letters of credit.
[2] In May 2024, the joint revolving credit facility was amended to remove Questar Gas as a co-borrower.
[3] The weighted-average interest rate of the outstanding commercial paper supported by the credit facility was 4.76% and 5.70% at December 31, 2024 and 2023, respectively.
v3.25.0.1
Long-Term and Short-Term Debt (Schedule of Line of Credit Facilities) (Parenthetical) (Detail) - USD ($)
 12 Months Ended
Dec. 31, 2024
Dec. 31, 2023
Minimum [Member]    
Debt Instrument [Line Items]    
Line of credit facility maturity date 2026-06  
Maximum [Member]    
Debt Instrument [Line Items]    
Line of credit facility maturity date 2028-06  
Joint Revolving Credit Facility    
Debt Instrument [Line Items]    
Facility limit [1] $ 1,000,000,000 [2] $ 1,000,000,000
Line of Credit Facility    
Debt Instrument [Line Items]    
Facility limit $ 500,000,000  
Commercial Paper    
Debt Instrument [Line Items]    
Line of credit facility, commitment fee percentage 4.76% 5.70%
Letter of Credit    
Debt Instrument [Line Items]    
Facility limit $ 1,000,000,000  
[1] A maximum of $1.0 billion of the facility is available to DESC, assuming adequate capacity is available after giving effect to uses by co-borrowers Dominion Energy and Virginia Power. A sub-limit for DESC is set within the facility limit but can be changed at the option of the co-borrowers multiple times per year. At December 31, 2024, the sub-limit for DESC was $500 million. If DESC has liquidity needs in excess of its sub-limit, the sub-limit may be changed or such needs may be satisfied through short-term borrowings from Dominion Energy. This credit facility matures in June 2026, with the potential to be extended by the borrowers to June 2028. The credit facility can be used to support bank borrowings and the issuance of commercial paper, as well as to support up to $1.0 billion (or the sub-limit, whichever is less) of letters of credit.
[2] In May 2024, the joint revolving credit facility was amended to remove Questar Gas as a co-borrower.
v3.25.0.1
Income Taxes (Narrative) (Detail) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2024
Dec. 31, 2023
Investments Owned Federal Income Tax Note [Line Items]    
Income tax benefit reasonably possible to occur $ 14 $ 11
Income tax examination, description The statute is closed for IRS examination of years prior to 2020. DESC is no longer subject to state and local income tax examinations by tax authorities for years prior to 2021.  
Decrease in Unrecognized Tax Benefits is Reasonably Possible $ 38  
Potential increase in earnings in next twelve months if tax benefits recognized $ 30  
v3.25.0.1
Income Taxes (Details of Income Tax Expense for Continuing Operations Including Noncontrolling Interests) (Detail) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2024
Dec. 31, 2023
Dec. 31, 2022
Current:      
Federal $ (6) $ 91 $ (69)
State 7 (70) (3)
Total current expense (benefit) 1 21 (72)
Deferred:      
Taxes before operating loss carryforwards and investment tax credits 16 (72) 135
Tax utilization expense (benefit) of operating loss carryforwards 36 43 33
State 13 95 36
Total deferred expense 65 66 204
Investment tax credits (1) (2) (1)
Total income tax expense [1] $ 65 $ 85 $ 131
[1] The significant expense categories and amounts in the segment information presented above align with the segment-level information that is regularly provided to DESC’s CODM.
v3.25.0.1
Income Taxes (Schedule of Effective Income Tax Rate Reconciliation) (Detail)
 12 Months Ended
Dec. 31, 2024
Dec. 31, 2023
Dec. 31, 2022
Income Tax Disclosure [Abstract]      
U.S. statutory rate 21.00% 21.00% 21.00%
Increases (reductions) resulting from:      
State taxes, net of federal benefit 4.00% 4.10% 4.70%
Amortization of federal investment tax credits (0.30%) (0.30%) (0.20%)
Reversal of excess deferred income taxes (5.60%) (4.70%) (4.60%)
Settlements of uncertain tax positions (3.50%) (2.20%) 0.00%
Other (0.10%) (0.20%) (0.20%)
Effective tax rate 15.50% 17.70% 20.70%
v3.25.0.1
Income Taxes (Schedule of Deferred Income Taxes) (Detail) - USD ($)
$ in Millions
Dec. 31, 2024
Dec. 31, 2023
Deferred income taxes:    
Total deferred income tax assets $ 662 $ 728
Total deferred income tax liabilities 2,059 2,033
Total net deferred income tax liabilities 1,397 1,305
Depreciation method and plant basis differences 1,271 1,203
Excess deferred income taxes (203) (212)
Unrecovered nuclear plant cost 420 450
DESC rate refund (49) (67)
Toshiba Settlement (133) (147)
Nuclear decommissioning (60) (51)
Deferred state income taxes 289 274
Federal benefit of deferred state income taxes (61) (60)
Deferred fuel, purchased energy and gas costs 11 32
Pension benefits 35 35
Other postretirement benefits (20) (17)
Loss and credit carryforwards (153) (185)
Other 50 50
Deferred investment tax credits 12 13
Total deferred taxes and deferred investment tax credits $ 1,409 $ 1,318
v3.25.0.1
Income Taxes (Summary of Deductible Loss and Credit Carryforwards) (Detail)
$ in Millions
 12 Months Ended
Dec. 31, 2024
USD ($)
Investments Owned Federal Income Tax Note [Line Items]  
Loss and Credit Carryforwards, Deductible Amount $ 1,248
Loss and Credit Carryforwards, Deferred Tax Asset 183 [1]
Federal  
Investments Owned Federal Income Tax Note [Line Items]  
Loss Carryforwards, Deductible Amount 361
Loss Carryforwards, Deferred Tax Asset $ 76 [1]
Loss Carryforwards, Expiration Period 2037
Federal | Production and Other Credits  
Investments Owned Federal Income Tax Note [Line Items]  
Credit Carryforwards, Deductible Amount $ 0
Credit Carryforwards, Deferred Tax Asset $ 22 [1]
Federal | Minimum [Member] | Production and Other Credits  
Investments Owned Federal Income Tax Note [Line Items]  
Credit Carryforwards, Expiration Period 2036
Federal | Maximum [Member] | Production and Other Credits  
Investments Owned Federal Income Tax Note [Line Items]  
Credit Carryforwards, Expiration Period 2038
State  
Investments Owned Federal Income Tax Note [Line Items]  
Loss Carryforwards, Deductible Amount $ 887
Loss Carryforwards, Deferred Tax Asset 44 [1]
State | Investment and Other Credits  
Investments Owned Federal Income Tax Note [Line Items]  
Credit Carryforwards, Deductible Amount 0
Credit Carryforwards, Deferred Tax Asset $ 41 [1]
State | Minimum [Member]  
Investments Owned Federal Income Tax Note [Line Items]  
Loss Carryforwards, Expiration Period 2037
State | Minimum [Member] | Investment and Other Credits  
Investments Owned Federal Income Tax Note [Line Items]  
Credit Carryforwards, Expiration Period 2026
State | Maximum [Member]  
Investments Owned Federal Income Tax Note [Line Items]  
Loss Carryforwards, Expiration Period 2042
State | Maximum [Member] | Investment and Other Credits  
Investments Owned Federal Income Tax Note [Line Items]  
Credit Carryforwards, Expiration Period 2033
[1] Includes $38 million of unrecognized tax benefits
v3.25.0.1
Income Taxes - Income Taxes (Summary of Deductible Loss and Credit Carryforwards) (Parenthetical) (Details) - USD ($)
$ in Millions
Dec. 31, 2024
Dec. 31, 2023
Dec. 31, 2022
Dec. 31, 2021
Valuation Allowance [Line Items]        
Unrecognized tax benefits $ 38 $ 62 $ 68 $ 62
Deferred Tax Asset [Member]        
Valuation Allowance [Line Items]        
Unrecognized tax benefits $ 38      
v3.25.0.1
Income Taxes (Reconciliation of Unrecognized Tax Benefits Roll Forward) (Detail) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2024
Dec. 31, 2023
Dec. 31, 2022
Income Tax Disclosure [Abstract]      
Balance at January 1, $ 62 $ 68 $ 62
Increases-prior period positions 5 5 6
Decreases-prior period positions (16) (11) (1)
Increases-current period positions 0 0 1
Settlements with tax authorities (13) 0 0
Balance at December 31, $ 38 $ 62 $ 68
v3.25.0.1
Derivative Financial Instruments (Narrative) (Detail) - USD ($)
$ in Millions
Dec. 31, 2024
Dec. 31, 2023
Derivative Instruments and Hedging Activities Disclosure [Abstract]    
Additional collateral to its counterparties $ 1 $ 4
Collateral already posted 0 0
Fair value of derivative instruments with credit-related contingent provisions that are in liability position and not fully collateralized with cash $ 1 $ 4
v3.25.0.1
Derivative Financial Instruments (Offsetting Assets and Liabilities) (Detail) - USD ($)
$ in Millions
Dec. 31, 2024
Dec. 31, 2023
Assets    
Derivative [Line Items]    
Assets not offset in the consolidated balance sheet $ 83 $ 0
Gross amounts not offset in the consolidated balance sheet, financial instruments 0 0
Gross amounts not offset in the consolidated balance sheet, cash collateral received 0 0
Gross amounts not offset in the consolidated balance sheet, net amounts 83 0
Over The Counter [Member] | Assets | Interest Rate Contract [Member]    
Derivative [Line Items]    
Assets not offset in the consolidated balance sheet 2 0
Gross amounts not offset in the consolidated balance sheet, financial instruments 0 0
Gross amounts not offset in the consolidated balance sheet, cash collateral received 0 0
Gross amounts not offset in the consolidated balance sheet, net amounts 2 0
Over The Counter [Member] | Assets | Commodity Contract [Member]    
Derivative [Line Items]    
Assets not offset in the consolidated balance sheet 81  
Gross amounts not offset in the consolidated balance sheet, financial instruments 0  
Gross amounts not offset in the consolidated balance sheet, cash collateral received 0  
Gross amounts not offset in the consolidated balance sheet, net amounts 81  
Liability    
Derivative [Line Items]    
Gross liabilities presented in the consolidated balance sheet 1 4
Gross amounts not offset in the consolidated balance sheet, financial instruments 0 0
Gross amounts not offset in the consolidated balance sheet, cash collateral paid 0 0
Gross amounts not offset in the consolidated balance sheet, net amounts 1 4
Liability | Over The Counter [Member] | Interest Rate Contract [Member]    
Derivative [Line Items]    
Gross liabilities presented in the consolidated balance sheet 1 4
Gross amounts not offset in the consolidated balance sheet, financial instruments 0 0
Gross amounts not offset in the consolidated balance sheet, cash collateral paid 0 0
Gross amounts not offset in the consolidated balance sheet, net amounts $ 1 $ 4
v3.25.0.1
Derivative Financial Instruments - (Offsetting Assets and Liabilities) (Parenthetical) (Details) - USD ($)
$ in Millions
Dec. 31, 2024
Dec. 31, 2023
Derivative Instruments and Hedging Activities Disclosure [Abstract]    
Derivative assets not subject to master netting or similar arrangements $ 289 $ 176
Derivative liability not subject to master netting or similar arrangements $ 0 $ 0
v3.25.0.1
Derivative Financial Instruments (Schedule of Volume of Derivative Activity) (Detail)
MWh in Millions
 12 Months Ended
Dec. 31, 2024
USD ($)
Bcf
MWh
Interest Rate Swap Current [Member]  
Derivative [Line Items]  
Interest rate | $ $ 0 [1]
Interest Rate Swap Current [Member] | Natural Gas (bcf) [Member]  
Derivative [Line Items]  
Basis | Bcf 32 [2]
Interest Rate Swap Current [Member] | Electricity [Member]  
Derivative [Line Items]  
Fixed price | MWh 2
Interest Rate Swap Noncurrent [Member]  
Derivative [Line Items]  
Interest rate | $ $ 71,000,000 [1]
Interest Rate Swap Noncurrent [Member] | Natural Gas (bcf) [Member]  
Derivative [Line Items]  
Basis | Bcf 30 [2]
Interest Rate Swap Noncurrent [Member] | Electricity [Member]  
Derivative [Line Items]  
Fixed price | MWh 21
[1] Maturity is determined based on final settlement period.
[2] Includes options.
v3.25.0.1
Derivative Financial Instruments (Fair Value of Derivatives) (Detail) - USD ($)
$ in Millions
Dec. 31, 2024
Dec. 31, 2023
Derivative [Line Items]    
Derivative Asset, Current [1] $ 63 $ 9
Derivative Asset, Noncurrent [1] 309 167
Derivative Liability, Noncurrent 1 4
Not Designated as Hedging Instrument [Member]    
Derivative [Line Items]    
Derivative Asset, Current $ 9 $ 63
Derivative Asset, Current, Statement of Financial Position [Extensible Enumeration] Other Assets, Current Other Assets, Current
Derivative Asset, Noncurrent [2] $ 309 $ 167
Derivative Asset, Noncurrent, Statement of Financial Position [Extensible Enumeration] Regulated Entity, Other Assets, Noncurrent Regulated Entity, Other Assets, Noncurrent
Derivative Assets $ 372 $ 176
Derivative Asset, Statement of Financial Position [Extensible Enumeration] Assets Assets
Derivative Liability, Current $ 0 $ 0
Derivative Liability, Current, Statement of Financial Position [Extensible Enumeration] Liabilities, Current Liabilities, Current
Derivative Liability, Noncurrent [2] $ 1 $ 4
Derivative Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration] Liabilities, Noncurrent Liabilities, Noncurrent
Derivative Liability $ 1 $ 4
Derivative Liability, Statement of Financial Position [Extensible Enumeration] Liabilities and Equity Liabilities and Equity
Not Designated as Hedging Instrument [Member] | Commodity Contract [Member]    
Derivative [Line Items]    
Derivative Asset, Current $ 63 $ 9
Derivative Asset, Current, Statement of Financial Position [Extensible Enumeration] Other Assets, Current Other Assets, Current
Derivative Asset, Noncurrent $ 307 $ 167
Derivative Asset, Noncurrent, Statement of Financial Position [Extensible Enumeration] Regulated Entity, Other Assets, Noncurrent Regulated Entity, Other Assets, Noncurrent
Derivative Liability, Current $ 0 $ 0
Derivative Liability, Current, Statement of Financial Position [Extensible Enumeration] Liabilities, Current Liabilities, Current
Derivative Liability, Noncurrent $ 0 $ 0
Derivative Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration] Liabilities, Noncurrent Liabilities, Noncurrent
Not Designated as Hedging Instrument [Member] | Interest Rate Contract [Member]    
Derivative [Line Items]    
Derivative Asset, Noncurrent $ 2 $ 0
Derivative Asset, Noncurrent, Statement of Financial Position [Extensible Enumeration] Regulated Entity, Other Assets, Noncurrent Regulated Entity, Other Assets, Noncurrent
Derivative Liability, Noncurrent $ 1 $ 4
Derivative Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration] Liabilities, Noncurrent Liabilities, Noncurrent
[1] See Note 16 for amounts attributable to affiliates.
[2] Represents net derivative activity deferred into and amortized out of regulatory assets/liabilities. Amounts deferred into regulatory assets/ liabilities have no associated effect in the Consolidated Statements of Comprehensive Income.
v3.25.0.1
Derivative Financial Instruments (Derivatives in Cash Flow Hedging Relationships) (Detail) - Cash Flow Hedging [Member] - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2024
Dec. 31, 2023
Dec. 31, 2022
Derivative [Line Items]      
Increase (Decrease) in Derivatives Subject to Regulatory Treatment [1] $ 1 $ 0 $ 11
Interest Rate Contract [Member]      
Derivative [Line Items]      
Increase (Decrease) in Derivatives Subject to Regulatory Treatment [1] $ 1 $ 0 $ 11
[1] Represents net derivative activity deferred into and amortized out of regulatory assets/liabilities. Amounts deferred into regulatory assets/ liabilities have no associated effect in the Consolidated Statements of Comprehensive Income.
v3.25.0.1
Derivative Financial Instruments (Derivatives Not Designated as Hedging Instruments) (Detail) - Not Designated as Hedging Instrument [Member] - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2024
Dec. 31, 2023
Dec. 31, 2022
Derivative [Line Items]      
Amount of Gain (Loss) Recognized in Income on Derivatives [1] $ 3 $ 4 $ 75
Commodity Contract [Member] | Purchased Power [Member]      
Derivative [Line Items]      
Amount of Gain (Loss) Recognized in Income on Derivatives [1] 3 6 77
Commodity Contract [Member] | Fuel Used in Electric Generation [Member]      
Derivative [Line Items]      
Amount of Gain (Loss) Recognized in Income on Derivatives [1] 1 0 0
Interest Rate Contract [Member]      
Derivative [Line Items]      
Amount of Gain (Loss) Recognized in Income on Derivatives [1] $ (1) $ (2) $ (2)
Derivative, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration] Interest expense from money pool transactions Interest expense from money pool transactions Interest expense from money pool transactions
[1] Includes derivative activity amortized out of regulatory assets/liabilities. Amounts deferred into regulatory assets/liabilities have no associated effect in the Consolidated Statements of Comprehensive Income.
v3.25.0.1
Fair Value Measurements, Including Derivatives (Schedule of Quantitative Information About Level 3 Fair Value Measurements) (Details) - Fair Value, Inputs, Level 3 [Member]
Dec. 31, 2024
USD ($)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]  
Total assets, fair value $ 370,000,000
Electricity [Member]  
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]  
Total assets, fair value 289,000,000
Natural gas [Member]  
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]  
Total assets, fair value 81,000,000 [1]
Minimum [Member] | Electricity [Member]  
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]  
Fair value inputs market price (per MWh) 31
Minimum [Member] | Natural gas [Member]  
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]  
Fair value inputs market price per decatherm $ 2
Fair value inputs price volatility 11.00%
Maximum [Member] | Electricity [Member]  
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]  
Fair value inputs market price (per MWh) $ 95
Maximum [Member] | Natural gas [Member]  
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]  
Fair value inputs market price per decatherm $ 7
Fair value inputs price volatility 73.00%
Weighted Average [Member] | Electricity [Member]  
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]  
Fair value inputs market price (per MWh) $ 55
Weighted Average [Member] | Natural gas [Member]  
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]  
Fair value inputs market price per decatherm $ 4
Fair value inputs price volatility 47.00% [2]
[1] Includes basis.
[2] Averages weighted by volume.
v3.25.0.1
Fair Value Measurements, Including Derivatives (Schedule of Assets and Liabilities Measured at Fair Value on Recurring Basis) (Details) - Fair value, recurring - USD ($)
$ in Millions
Dec. 31, 2024
Dec. 31, 2023
Assets    
Total assets $ 401 $ 176
Liabilities    
Total liabilities 1 4
Cash Equivalents and Other [Member]    
Assets    
Total assets 29  
Commodity Contract [Member]    
Assets    
Total assets 370 176
Interest Rate Contract [Member]    
Assets    
Total assets 2  
Liabilities    
Total liabilities 1 4
Level 1    
Assets    
Total assets 29 0
Liabilities    
Total liabilities 0 0
Level 1 | Cash Equivalents and Other [Member]    
Assets    
Total assets 29  
Level 1 | Commodity Contract [Member]    
Assets    
Total assets 0 0
Level 1 | Interest Rate Contract [Member]    
Assets    
Total assets 0  
Liabilities    
Total liabilities 0 0
Level 2    
Assets    
Total assets 2 0
Liabilities    
Total liabilities 1 4
Level 2 | Cash Equivalents and Other [Member]    
Assets    
Total assets 0  
Level 2 | Commodity Contract [Member]    
Assets    
Total assets 0 0
Level 2 | Interest Rate Contract [Member]    
Assets    
Total assets 2  
Liabilities    
Total liabilities 1 4
Level 3    
Assets    
Total assets 370 176
Liabilities    
Total liabilities 0 0
Level 3 | Cash Equivalents and Other [Member]    
Assets    
Total assets 0  
Level 3 | Commodity Contract [Member]    
Assets    
Total assets 370 176
Level 3 | Interest Rate Contract [Member]    
Assets    
Total assets 0  
Liabilities    
Total liabilities $ 0 $ 0
v3.25.0.1
Fair Value Measurements, Including Derivatives (Schedule of Assets and Liabilities Measured at Fair Value on Recurring Basis and Included in Level 3) (Details) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2024
Dec. 31, 2023
Dec. 31, 2022
Regulatory Assets      
Beginning balance $ 176 $ 251 $ 148
Included in earnings:      
Purchased power 3 6 77
Fuel used in electric generation 1 0 0
Gas purchased for resale 1 0 0
Settlements (17) (6) (77)
Purchases 91 0 0
Ending balance 370 176 251
Other Regulatory Assets Liabilities      
Included in earnings:      
Included in regulatory assets/liabilities $ 115 $ (75) $ 103
v3.25.0.1
Fair Value Measurements, Including Derivatives (Schedule of Assets and Liabilities Measured at Fair Value on Recurring Basis) (Narrative) (Details) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2024
Dec. 31, 2023
Dec. 31, 2022
Derivative Instruments and Hedging Activities Disclosure [Abstract]      
Unrealized gains and losses $ 0 $ 0 $ 0
v3.25.0.1
Fair Value Measurements, Including Derivatives (Schedule of Carrying Values and Estimated Fair Values of Debt Instruments) (Detail) - USD ($)
$ in Millions
Dec. 31, 2024
Dec. 31, 2023
Carrying Amount    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Long-term debt [1] $ 4,220 $ 4,219
Affiliated long-term debt [2] 230 230
Estimated Fair Value    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Long-term debt [1],[3] 4,142 4,301
Affiliated long-term debt [2],[3] $ 230 $ 230
[1] Carrying amount includes current portions, if any, included in securities due within one year and amounts which represent the unamortized debt issuance costs and discount or premium.
[2] Carrying amount includes current portions presented in affiliated and related party payables, as applicable.
[3] Fair value is estimated using market prices, where available, and interest rates currently available for issuance of debt with similar terms and remaining maturities. All fair value measurements are classified as Level 2. The carrying amount of debt issuances with short-term maturities and variable rates refinanced at current market rates is a reasonable estimate of their fair value.
v3.25.0.1
Asset Retirement Obligations (Narrative) (Detail) - USD ($)
$ in Millions
Dec. 31, 2024
Dec. 31, 2023
Asset Retirement Obligation Disclosure [Abstract]    
Asset retirement obligation, other conditional obligations $ 815 $ 420
Asset retirement obligation, nuclear decommissioning $ 324 $ 311
v3.25.0.1
Asset Retirement Obligations (Schedule of Reconciliation of the Carrying Amount of AROs) (Detail) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2024
Dec. 31, 2023
Asset Retirement Obligation Disclosure [Abstract]    
Beginning balance $ 731 $ 628
Liabilities incurred [1] 654 7
Liabilities settled (79) (14)
Accretion expense 46 29
Revisions in estimated cash flows [2] (213) 81
Ending balance $ 1,139 $ 731
[1] In 2024, primarily reflects AROs related to CCR remediation as discussed in Note 12.
[2] In 2024, primarily reflects a revision related to CCR remediation costs as discussed in Note 12. In 2023, there was an increase in estimated costs associated with certain coal-fired generating units, including revisions following the approval of closure plans for a facility previously taken out of service.
v3.25.0.1
Employee Benefit Plans and Equity Compensation Plan (Narrative) (Detail) - USD ($)
 12 Months Ended
Dec. 31, 2025
Dec. 31, 2024
Dec. 31, 2023
Dec. 31, 2022
Jan. 31, 2025
Defined Benefit Plan Disclosure [Line Items]          
Defined benefit plan, accumulated benefit obligation   $ 574,000,000 $ 579,000,000    
Defined benefit plan, annual rate of increase in the per capita cost of covered health care benefits   7.00%      
Defined benefit plan, ultimate health care cost trend rate   5.00%      
Defined benefit plan, contributions by employer   $ 8,000,000 0 $ 0  
Pension and other postretirement benefits   109,000,000 115,000,000    
Defined contribution plan, employer matching contributions   $ 15,000,000 14,000,000 $ 13,000,000  
Forecast [Member]          
Defined Benefit Plan Disclosure [Line Items]          
Defined benefit plan, assumptions used calculating net periodic benefit cost, expected long-term rate of return on plan assets 7.35%        
Public Equity [Member] | Subsequent Event [Member]          
Defined Benefit Plan Disclosure [Line Items]          
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage         30.00%
Global Equities [Member]          
Defined Benefit Plan Disclosure [Line Items]          
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage   45.00%      
Fixed Income [Member]          
Defined Benefit Plan Disclosure [Line Items]          
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage   53.00%      
Fixed Income [Member] | Subsequent Event [Member]          
Defined Benefit Plan Disclosure [Line Items]          
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage         27.00%
Other Alternative Investments [Member] | Subsequent Event [Member]          
Defined Benefit Plan Disclosure [Line Items]          
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage         43.00%
Cash [Member]          
Defined Benefit Plan Disclosure [Line Items]          
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage   2.00%      
U.S Fixed Income [Member]          
Defined Benefit Plan Disclosure [Line Items]          
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage   60.00%      
Non-U.S Fixed Income [Member]          
Defined Benefit Plan Disclosure [Line Items]          
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage   40.00%      
Summer [Member]          
Defined Benefit Plan Disclosure [Line Items]          
Defined benefit plan, shared costs deferred with joint ownership   $ 9,000,000 19,000,000    
Pension Benefits [Member]          
Defined Benefit Plan Disclosure [Line Items]          
Recognized actuarial gain (loss)   10,000,000 (1,000,000)    
Defined benefit plan gain (loss) due to decrease in discount rate   15,000,000 10,000,000    
Defined benefit plan, actuarial gain (loss) in discount rate offset   (5,000,000) 9,000,000    
Actuarial (gain) loss   $ (10,000,000) $ 1,000,000    
Defined benefit plan, assumptions used calculating net periodic benefit cost, expected long-term rate of return on plan assets   7.00% 7.00% 7.00%  
Defined benefit plan, expected contributions in 2024   $ 3,000,000      
Defined benefit plan, net periodic benefit (credit) cost   11,000,000 $ 19,000,000 $ (19,000,000)  
Other Postretirement Benefits [Member]          
Defined Benefit Plan Disclosure [Line Items]          
Defined benefit plan gain (loss) due to decrease in discount rate   7,000,000 (4,000,000)    
Defined benefit plan, actuarial gain (loss) in discount rate offset   (1,000,000) 3,000,000    
Actuarial (gain) loss   $ (6,000,000) $ 1,000,000    
Defined benefit plan, ultimate health care cost trend rate   5.00% 5.00% 5.00%  
Defined benefit plan, net periodic benefit (credit) cost   $ 5,000,000 $ 5,000,000 $ 7,000,000  
Other Postretirement Benefits [Member] | Summer [Member]          
Defined Benefit Plan Disclosure [Line Items]          
Defined benefit plan, shared costs deferred with joint ownership   10,000,000 10,000,000    
Dominion Energy Defined Benefit Plans [Member]          
Defined Benefit Plan Disclosure [Line Items]          
Defined benefit plan, contributions by employer   0 0 1,000,000  
Defined benefit plan, net periodic benefit (credit) cost   2,000,000 2,000,000 $ 1,000,000  
Pension and other postretirement benefits   $ 7,000,000 $ 6,000,000    
v3.25.0.1
Employee Benefit Plans and Equity Compensation Plan (Changes in Benefit Obligations) (Detail) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2024
Dec. 31, 2023
Dec. 31, 2022
Pension Benefits [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Beginning balance $ 584 $ 580  
Service cost 8 8 $ 8
Interest cost 31 33 21
Amendments 7 1  
Actuarial (gain) loss (10) 1  
Benefits paid (43) (39)  
Ending balance 577 584 580
Other Postretirement Benefits [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Beginning balance 120 121  
Service cost 1 1 1
Interest cost 8 8 6
Amendments 0 0  
Actuarial (gain) loss (6) 1  
Benefits paid (11) (11)  
Ending balance $ 112 $ 120 $ 121
v3.25.0.1
Employee Benefit Plans and Equity Compensation Plan (Significant Assumptions Used to Determine Benefit Obligations) (Detail)
Dec. 31, 2024
Dec. 31, 2023
Pension Benefits [Member]    
Defined Benefit Plan Disclosure [Line Items]    
Annual discount rate used to determine benefit obligation 5.84% 5.39%
Assumed annual rate of future salary increases for projected benefit obligation 3.47% 3.54%
Crediting interest rate for cash balance plans 4.59% 4.14%
Other Postretirement Benefits [Member]    
Defined Benefit Plan Disclosure [Line Items]    
Annual discount rate used to determine benefit obligation 5.86% 5.42%
v3.25.0.1
Employee Benefit Plans and Equity Compensation Plan (Funded Status) (Detail) - USD ($)
$ in Millions
Dec. 31, 2024
Dec. 31, 2023
Dec. 31, 2022
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets $ 603 $ 588 $ 561
Pension Benefits [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 603 588  
Benefit obligation 577 584 580
Funded status 26 4  
Other Postretirement Benefits [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 0 0  
Benefit obligation 112 120 $ 121
Funded status $ (112) $ (120)  
v3.25.0.1
Employee Benefit Plans and Equity Compensation Plan (Amounts Recognized on Consolidated Balance Sheets) (Detail) - USD ($)
$ in Millions
Dec. 31, 2024
Dec. 31, 2023
Pension Benefits [Member]    
Defined Benefit Plan Disclosure [Line Items]    
Noncurrent assets $ 26 $ 4
Current liability 0 0
Noncurrent liability 0 0
Other Postretirement Benefits [Member]    
Defined Benefit Plan Disclosure [Line Items]    
Noncurrent assets 0 0
Current liability (10) (11)
Noncurrent liability $ (102) $ (109)
v3.25.0.1
Employee Benefit Plans and Equity Compensation Plan (Amounts Recognized in AOCI) (Detail) - USD ($)
$ in Millions
Dec. 31, 2024
Dec. 31, 2023
Pension Benefits [Member]    
Defined Benefit Plan Disclosure [Line Items]    
Net actuarial (gain) loss $ 2 $ 2
Other Postretirement Benefits [Member]    
Defined Benefit Plan Disclosure [Line Items]    
Net actuarial (gain) loss $ (1) $ (1)
v3.25.0.1
Employee Benefit Plans and Equity Compensation Plan (Amounts Recognized in Regulatory Assets) (Detail) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2024
Dec. 31, 2023
Pension Benefits [Member]    
Defined Benefit Plan Disclosure [Line Items]    
Net actuarial (gain) loss $ 98 $ 126
Prior service cost 7 1
Total 105 127
Other Postretirement Benefits [Member]    
Defined Benefit Plan Disclosure [Line Items]    
Net actuarial (gain) loss (43) (41)
Prior service cost 0 0
Total $ (43) $ (41)
v3.25.0.1
Employee Benefit Plans (Change in Fair Value of Plan Assets) (Detail) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2024
Dec. 31, 2023
Retirement Benefits [Abstract]    
Beginning balance $ 588 $ 561
Actual return (loss) on plan assets 50 66
Benefits paid (43) (39)
Contributions 8 0
Ending balance $ 603 $ 588
v3.25.0.1
Employee Benefit Plans (Schedule of Fair Value Measurements By Category) (Detail) - USD ($)
$ in Millions
Dec. 31, 2024
Dec. 31, 2023
Defined Benefit Plan Disclosure [Line Items]    
Total recorded at fair value $ 294 $ 156
Commingled funds/collective trust funds [1] 0 436
Total recorded at NAV [1] 0 436
Total investments [2] 294 592
Level 1    
Defined Benefit Plan Disclosure [Line Items]    
Total recorded at fair value 294 4
Level 2    
Defined Benefit Plan Disclosure [Line Items]    
Total recorded at fair value 0 152
Level 3    
Defined Benefit Plan Disclosure [Line Items]    
Total recorded at fair value 0 0
Cash and cash equivalents    
Defined Benefit Plan Disclosure [Line Items]    
Total recorded at fair value 294 5
Cash and cash equivalents | Level 1    
Defined Benefit Plan Disclosure [Line Items]    
Total recorded at fair value 294 4
Cash and cash equivalents | Level 2    
Defined Benefit Plan Disclosure [Line Items]    
Total recorded at fair value 0 1
Cash and cash equivalents | Level 3    
Defined Benefit Plan Disclosure [Line Items]    
Total recorded at fair value 0 0
Corporate Debt Securities    
Defined Benefit Plan Disclosure [Line Items]    
Total recorded at fair value 0 137
Corporate Debt Securities | Level 1    
Defined Benefit Plan Disclosure [Line Items]    
Total recorded at fair value 0 0
Corporate Debt Securities | Level 2    
Defined Benefit Plan Disclosure [Line Items]    
Total recorded at fair value 0 137
Corporate Debt Securities | Level 3    
Defined Benefit Plan Disclosure [Line Items]    
Total recorded at fair value 0 0
Government and Other Debt Instruments    
Defined Benefit Plan Disclosure [Line Items]    
Total recorded at fair value 0 14
Government and Other Debt Instruments | Level 1    
Defined Benefit Plan Disclosure [Line Items]    
Total recorded at fair value 0 0
Government and Other Debt Instruments | Level 2    
Defined Benefit Plan Disclosure [Line Items]    
Total recorded at fair value 0 14
Government and Other Debt Instruments | Level 3    
Defined Benefit Plan Disclosure [Line Items]    
Total recorded at fair value $ 0 $ 0
[1] These investments that are measured at fair value using the NAV per share (or its equivalent) as a practical expedient are not required to be categorized in the fair value hierarchy.
[2] Excludes net assets related to pending sales of securities of $309 million at December 31, 2024. Excludes net assets related to pending sales of securities of $1 million, net accrued income of $1 million, and includes net assets related to pending purchases of securities of $6 million at December 31, 2023.
v3.25.0.1
Employee Benefit Plans (Schedule of Fair Value Measurements By Category) (Parenthetical) (Detail) - Pension Benefits [Member] - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2024
Dec. 31, 2023
Defined Benefit Plan Disclosure [Line Items]    
Pending sales of securities $ 309 $ 1
Net accrued income   1
Pending purchases of securities   $ 6
v3.25.0.1
Employee Benefit Plans (Expected Benefit Payments) (Detail)
$ in Millions
Dec. 31, 2024
USD ($)
Pension Benefits [Member]  
Defined Benefit Plan Disclosure [Line Items]  
Defined benefit plan, expected benefit payments, 2025 $ 50
Defined benefit plan, expected benefit payments, 2026 46
Defined benefit plan, expected benefit payments, 2027 45
Defined benefit plan, expected benefit payments, 2028 47
Defined benefit plan, expected benefit payments, 2029 46
Defined benefit plan, expected benefit payments, 2030-2034 240
Other Postretirement Benefits [Member]  
Defined Benefit Plan Disclosure [Line Items]  
Defined benefit plan, expected benefit payments, 2025 11
Defined benefit plan, expected benefit payments, 2026 11
Defined benefit plan, expected benefit payments, 2027 11
Defined benefit plan, expected benefit payments, 2028 11
Defined benefit plan, expected benefit payments, 2029 11
Defined benefit plan, expected benefit payments, 2030-2034 $ 54
v3.25.0.1
Employee Benefit Plans (Components of Net Periodic Benefit Cost) (Detail) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2024
Dec. 31, 2023
Dec. 31, 2022
Pension Benefits [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Service cost $ 8 $ 8 $ 8
Interest cost 31 33 21
Expected return on assets (37) (34) (49)
Amortization of actuarial losses (gains) 9 12 1
Net periodic benefit cost 11 19 (19)
Other Postretirement Benefits [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Service cost 1 1 1
Interest cost 8 8 6
Expected return on assets 0 0 0
Amortization of actuarial losses (gains) (4) (4) 0
Net periodic benefit cost $ 5 $ 5 $ 7
v3.25.0.1
Employee Benefit Plans and Equity Compensation Plan (Schedule of Defined Benefit Plan, Amounts Recognized in Accumulated Other Comprehensive Income (Loss)) (Detail) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2024
Dec. 31, 2023
Dec. 31, 2022
Pension Benefits [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Current year actuarial (gain) loss $ 0 $ (1) $ 2
Total recognized in other comprehensive income 0 (1) 2
Other Postretirement Benefits [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Current year actuarial (gain) loss 0 0 (1)
Total recognized in other comprehensive income $ 0 $ 0 $ (1)
v3.25.0.1
Employee Benefit Plans and Equity Compensation Plan (Schedule of Defined Benefit Plan Amounts Recognized in Regulatory Assets) (Detail) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2024
Dec. 31, 2023
Dec. 31, 2022
Pension Benefits [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Regulatory assets, pension and other postretirement benefit plans, net unamortized gain (loss) arising during the period, net of tax $ (20) $ (27) $ 95
Regulatory assets, amortization of actuarial gain (loss), pension and other postretirement benefit plans, net of tax (8) (11) (1)
Regulatory assets, current year prior service cost, pension and other postretirement benefit plans, net of tax 6 1 0
Regulatory assets, total recognized in regulatory assets, pension and other postretirement benefit plans, net of tax (22) (37) 94
Other Postretirement Benefits [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Regulatory assets, pension and other postretirement benefit plans, net unamortized gain (loss) arising during the period, net of tax (5) 2 (41)
Regulatory assets, amortization of actuarial gain (loss), pension and other postretirement benefit plans, net of tax 3 3 0
Regulatory assets, current year prior service cost, pension and other postretirement benefit plans, net of tax 0 0 0
Regulatory assets, total recognized in regulatory assets, pension and other postretirement benefit plans, net of tax $ (2) $ 5 $ (41)
v3.25.0.1
Employee Benefit Plans and Equity Compensation Plan (Schedule of Assumptions Used in Determining Net Periodic Benefit Cost) (Detail)
 12 Months Ended
Dec. 31, 2024
Dec. 31, 2023
Dec. 31, 2022
Defined Benefit Plan Disclosure [Line Items]      
Ultimate health care cost trend rate 5.00%    
Pension Benefits [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Discount rate 5.39% 5.69% 3.06%
Expected return on plan assets 7.00% 7.00% 7.00%
Rate of compensation increase 3.54% 3.93% 3.71%
Crediting interest rate for cash balance plans 4.14% 4.44% 1.81%
Other Postretirement Benefits [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Discount rate 5.42% 5.70% 3.11%
Health care cost trend rate 7.00% 7.00% 6.25%
Ultimate health care cost trend rate 5.00% 5.00% 5.00%
Year achieved 2031 2030  
Other Postretirement Benefits [Member] | Minimum [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Year achieved     2026
Other Postretirement Benefits [Member] | Maximum [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Year achieved     2027
v3.25.0.1
Commitments and Contingencies (Narrative) (Detail)
$ in Millions
 12 Months Ended
Dec. 31, 2024
USD ($)
Loss Contingencies [Line Items]  
Personal injury or wrongful death charges $ 11
Insurance receivable 10
Reserves related to personal injury or wrongful death cases $ 7
v3.25.0.1
Commitments and Contingencies (Environmental Matters) (Narrative) (Detail)
gal in Millions
 1 Months Ended 3 Months Ended 12 Months Ended
Oct. 31, 2014
MGD
Facility
May 31, 2024
Station
Oct. 31, 2020
Nov. 30, 2019
gal
Sep. 30, 2017
Petition
Aug. 31, 2016
T
Dec. 31, 2024
USD ($)
Facility
Jun. 30, 2024
USD ($)
Dec. 31, 2024
USD ($)
MGD
Indicator
Product
Facility
Dec. 31, 2023
USD ($)
Dec. 31, 2022
USD ($)
Loss Contingencies [Line Items]                      
Increase in regulatory assets                 $ (79,000,000) $ (334,000,000) $ 532,000,000
Measurement of groundwater withdrawals | gal       3              
Number of manufacturing gas plant decommissioned sites that contain residues of byproduct chemicals | Product                 4    
Environmental remediation costs recognized in regulatory assets             $ 33,000,000   $ 33,000,000    
Number of facilities inactive subject to final rule | Facility                 3    
Maximum [Member]                      
Loss Contingencies [Line Items]                      
Estimated environmental remediation activities at manufacturing gas plant sites                 $ 1,000,000    
Unfavorable Regulatory Action | CWA                      
Loss Contingencies [Line Items]                      
Number of mandatory facility specific factors | Indicator                 5    
Number of optional facility specific factors | Indicator                 6    
Electric generating stations with water withdrawals with heightened entrainment analysis under CWA | MGD                 2,000,000    
Unfavorable Regulatory Action | DESC | CWA                      
Loss Contingencies [Line Items]                      
Number of DESC facilities subject to final regulations | Facility 5                    
Carbon Regulations                      
Loss Contingencies [Line Items]                      
Significant emission rate per year CO2 equivalent | T           75,000          
EPA                      
Loss Contingencies [Line Items]                      
Increase in asset retirement obligations               $ 655,000,000      
Increase in property, plant and equipment               353,000,000      
Increase in regulatory assets               302,000,000      
Decrease in ARO and property, plant and equipment               $ 215,000,000      
Number of facility | Facility             1        
Number of petition agreed for reconsideration | Petition         2            
EPA | Maximum [Member]                      
Loss Contingencies [Line Items]                      
Number of stations inactive subject to final rule | Station   7                  
EPA | Unfavorable Regulatory Action                      
Loss Contingencies [Line Items]                      
Electric generating stations with water withdrawals under CWA | MGD 125,000,000                    
EPA | Unfavorable Regulatory Action | CWA | Final Rule to Revise Effluent Limitations Guidelines for Steam Electric Power Generating Category                      
Loss Contingencies [Line Items]                      
Number of separate petitions for reconsideration granted | MGD 2                    
Loss contingencies individual facilities circumstances period   2034                  
Loss contingencies facility retirement period   2034                  
EPA | Unfavorable Regulatory Action | CWA | Final Rule to Revise Effluent Limitations Guidelines for Steam Electric Power Generating Category | Minimum [Member]                      
Loss Contingencies [Line Items]                      
Loss contingencies individual facilities circumstances period     2021                
EPA | Unfavorable Regulatory Action | CWA | Final Rule to Revise Effluent Limitations Guidelines for Steam Electric Power Generating Category | Maximum [Member]                      
Loss Contingencies [Line Items]                      
Loss contingencies individual facilities circumstances period   2029 2028                
Environmental Protection Agency And State Regulatory Agencies | Hydroelectric Facilities                      
Loss Contingencies [Line Items]                      
Number of DESC hydroelectric facilities subject to regulations | Facility                 5    
v3.25.0.1
Commitments and Contingencies (Claims and Litigation) (Narrative) (Detail) - USD ($)
 1 Months Ended 3 Months Ended 12 Months Ended
Jul. 31, 2023
Jun. 30, 2023
Sep. 30, 2022
Jun. 30, 2022
May 31, 2022
Aug. 31, 2021
Jun. 30, 2021
Dec. 31, 2020
Jun. 30, 2018
Mar. 31, 2023
Dec. 31, 2024
Dec. 31, 2023
Dec. 31, 2022
Loss Contingencies [Line Items]                          
Reserves for litigation and regulatory proceedings                     $ 7,000,000 $ 3,000,000  
Proportionate ownership share in project                 100.00%        
Proposed assessment amount from SCDOR audit                 $ 410,000,000        
Litigation settlement expense awarded               $ 165,000,000          
Real estate transfer to satisfy obligation under settlement       $ 51,000,000                  
SCDOR                          
Loss Contingencies [Line Items]                          
Value of certain utility and non-utility properties to be conveyed                         $ 3,000,000
Non utility property fair value     $ 28,000,000                    
Fair value of certain utility property transferred                   $ 10,000,000      
Fair value of certain remaining utility property transferred   $ 11,000,000                      
Common Stock | Dominion Energy                          
Loss Contingencies [Line Items]                          
Litigation settlement through cash             $ 43,000,000            
Litigation settlement through stock issuance         900,000 600,000              
Other Income (Expense), Net | SCDOR                          
Loss Contingencies [Line Items]                          
Gain from transferred utility property                     9,000,000    
Gain from transferred utility property after-tax                     $ 7,000,000    
Gain from transferred non utility property                         19,000,000
Gain from transferred non utility property, after tax                         $ 14,000,000
Gain from transferred remaining utility property                       11,000,000  
Gain from transferred remaining utility property, after tax                       $ 8,000,000  
Maximum [Member] | SCDOR                          
Loss Contingencies [Line Items]                          
Cash payment $ 1,000,000                        
v3.25.0.1
Commitments and Contingencies (Nuclear Insurance) (Narrative) (Details) - USD ($)
 3 Months Ended 12 Months Ended
Mar. 31, 2024
Dec. 31, 2024
Dec. 31, 2023
Dec. 31, 2022
Loss Contingencies [Line Items]        
Proceeds from legal settlements of share of claims incurred in previous year   $ 2,000,000 $ 6,000,000 $ 1,000,000
Nuclear Insurance        
Loss Contingencies [Line Items]        
Maximum liability protection per nuclear incident amount $ 16,300,000,000 16,300,000,000 16,200,000,000  
Maximum liability each nuclear plant is insured against $ 500,000,000 450,000,000 $ 450,000,000  
Amount that could be assessed for each licensed reactor   166,000,000    
Amount that could be assessed for each licensed reactor per year   $ 25,000,000    
Inflation adjustment period for nuclear insurance   5 years    
NEIL maximum insurance coverage to nuclear facility for property damage and outage costs   $ 1,060,000,000.00    
NEIL maximum insurance coverage to nuclear facility for property damage and outage costs from non-nuclear event   1,000,000    
NEIL aggregate maximum loss for any single loss occurrence   1,060,000,000.00    
NEIL maximum retrospective premium assessment   7,000,000    
EMANI maximum insurance coverage for property damage and outage costs from non-nuclear event   1,000,000    
DESC Summer | Nuclear Insurance        
Loss Contingencies [Line Items]        
Amount that could be assessed for each licensed reactor   111,000,000    
Amount that could be assessed for each licensed reactor per year   $ 9,000,000    
v3.25.0.1
Commitments and Contingencies (Schedule of Long-Term Purchase Agreements) (Detail)
$ in Millions
Dec. 31, 2024
USD ($)
 [1],[2]
Commitments and Contingencies Disclosure [Abstract]  
Purchased electric capacity, 2025 $ 85
Purchased electric capacity, 2026 88
Purchased electric capacity, 2027 89
Purchased electric capacity, 2028 88
Purchased electric capacity, 2029 87
Purchased electric capacity, Thereafter 473
Purchased electric capacity, Total $ 910
[1] Commitments represent estimated amounts payable for energy under power purchase contracts with qualifying facilities which expire at various dates through 2040. Energy payments are generally based on fixed dollar amounts per month and totaled $70 million in 2024, $70 million in 2023 and $75 million in 2022.
[2] Includes affiliated amounts with certain solar facilities of $173 million.
v3.25.0.1
Commitments and Contingencies (Schedule of Long-Term Purchase Agreements) (Parenthetical) (Detail) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2024
Dec. 31, 2023
Dec. 31, 2022
Long Term Purchase Commitment [Line Items]      
Energy payments under power purchase contracts $ 70 $ 70 $ 75
Solar Affiliates [Member]      
Long Term Purchase Commitment [Line Items]      
Affiliated amount for long term commitments $ 173    
v3.25.0.1
Commitments and Contingencies (Surety Bonds) (Narrative) (Details)
Dec. 31, 2024
USD ($)
Surety Bond  
Loss Contingencies [Line Items]  
Guarantee obligation $ 24,000,000
v3.25.0.1
Leases (Schedule of Lease Assets and Liabilities Recorded in Consolidated Balance Sheets) (Detail) - USD ($)
$ in Millions
Dec. 31, 2024
Dec. 31, 2023
Leases [Abstract]    
Operating lease assets [1] $ 20 $ 18
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration] Total deferred debits and other assets Total deferred debits and other assets
Finance lease assets [2] $ 3 $ 6
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration] Utility plant, net Utility plant, net
Total lease assets $ 23 $ 24
Operating lease liabilities - current [3] $ 3 $ 2
Operating Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration] Other Liabilities, Current Other Liabilities, Current
Operating lease liabilities - noncurrent [4] $ 18 $ 17
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration] Liabilities, Noncurrent Liabilities, Noncurrent
Finance lease liabilities - current [5] $ 2 $ 3
Finance Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration] Liabilities, Current Liabilities, Current
Finance lease liabilities - noncurrent $ 2 $ 4
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration] Finance lease liabilities - noncurrent Finance lease liabilities - noncurrent
Total lease liabilities $ 25 $ 26
[1] Included in other deferred debits and other assets in the Consolidated Balance Sheets.
[2] Included in utility plant, net, in the Consolidated Balance Sheets, net of $15 million and $17 million of accumulated amortization at December 31, 2024 and December 31, 2023, respectively.
[3] Included in other current liabilities in the Consolidated Balance Sheets.
[4] Included in other deferred credits and other liabilities in the Consolidated Balance Sheets.
[5] Included in securities due within one year in the Consolidated Balance Sheets.
v3.25.0.1
Leases (Schedule of Lease Assets and Liabilities Recorded in Consolidated Balance Sheets) (Parenthetical) (Detail) - USD ($)
$ in Millions
Dec. 31, 2024
Dec. 31, 2023
Utility Plant, Net    
Finance lease assets, accumulated amortization $ 15 $ 17
v3.25.0.1
Leases (Summary of Total Lease Cost) (Detail) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2024
Dec. 31, 2023
Dec. 31, 2022
Leases [Abstract]      
Finance lease cost, amortization $ 3 $ 3 $ 4
Finance lease cost, interest 0 0 1
Operating lease cost 4 5 4
Short-term lease cost 1 2 2
Total lease cost $ 8 $ 10 $ 11
v3.25.0.1
Leases (Cash Paid for Amounts Included in Measurement of Lease Liabilities) (Detail) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2024
Dec. 31, 2023
Dec. 31, 2022
Leases [Abstract]      
Operating cash flows from finance leases $ 0 $ 0 $ 1
Operating cash flows from operating leases 4 4 6
Financing cash flows from finance leases $ 3 $ 4 $ 4
v3.25.0.1
Leases (Summary of Weighted-average Remaining Lease Term And Discount Rate for Operating and Finance Leases) (Detail)
Dec. 31, 2024
Dec. 31, 2023
Leases [Abstract]    
Weighted-average remaining lease term - finance leases 3 years 3 years
Weighted-average remaining lease term - operating leases 16 years 18 years
Weighted-average discount rate - finance leases 3.17% 2.96%
Weighted-average discount rate - operating leases 4.34% 4.12%
v3.25.0.1
Leases (Schedule of Maturity Analysis of Operating and Finance Lease Liabilities) (Detail)
$ in Millions
Dec. 31, 2024
USD ($)
Operating Lease Liabilities, Payments Due [Abstract]  
Maturity of operating lease liabilities, 2025 $ 3
Maturity of operating lease liabilities, 2026 3
Maturity of operating lease liabilities, 2027 2
Maturity of operating lease liabilities, 2028 2
Maturity of operating lease liabilities, 2029 2
Maturity of operating lease liabilities, after 2029 20
Maturity of operating lease liabilities, total undiscounted lease payments 32
Operating lease liabilities, present value adjustment (11)
Present value of operating lease liabilities 21
Finance Lease Liabilities, Payments, Due [Abstract]  
Maturity of finance lease liabilities, 2025 2
Maturity of finance lease liabilities, 2026 1
Maturity of finance lease liabilities, 2027 1
Maturity of finance lease liabilities, 2028 0
Maturity of finance lease liabilities, 2029 0
Maturity of finance lease liabilities, after 2029 0
Maturity of finance lease liabilities, total undiscounted lease payments 4
Finance lease liabilities, present value adjustment 0
Present value of finance lease liabilities $ 4
v3.25.0.1
Operating Segments (Narrative) (Detail) - Operating Segments - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2024
Dec. 31, 2023
Dec. 31, 2022
Corporate and Other      
Segment Reporting Information [Line Items]      
After- tax net income (loss) $ (47) $ 18 $ (3)
Dominion Energy South Carolina, Inc. [Member]      
Segment Reporting Information [Line Items]      
Benefit related to real estate transactions   28  
Charge in connection with the electric base rate case 58    
Charge in connection with the electric base rate case, after tax $ 44    
Benefit related to real estate transactions, after tax   $ 21  
v3.25.0.1
Operating Segments - Schedule of Segment Information (Details) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2024
Dec. 31, 2023
Dec. 31, 2022
Segment Reporting Information [Line Items]      
Operating Revenue [1] $ 3,173 $ 3,028 $ 3,783
Fuel used in electric generation [2] 603 582 1,000
Purchased power [1],[2] 68 72 137
Gas purchased for resale [2] 245 243 433
Other operations and maintenance [2],[3] 717 602 630
Depreciation and amortization [2] 546 531 507
Other taxes [1],[2] 300 292 277
Total operating expenses 2,479 2,322 2,984
Other income, net [4] (1) 24 55
Interest charges, net of AFUDC [2] 276 250 220
Income tax expense (benefit) [2] 65 85 131
Deferred cost of employee benefit plans, net of tax [4] 0 1 (1)
Comprehensive Income Attributable to Noncontrolling Interest [4] 23 21 20
Comprehensive Income (Loss) Available (Attributable) to Common Shareholder 329 375 482
Capital expenditures 1,105 957 697
Total assets 17,041 15,857  
Dominion Energy South Carolina, Inc. [Member]      
Segment Reporting Information [Line Items]      
Operating Revenue 3,173 3,028 3,783
Fuel used in electric generation [2] 603 582 1,000
Purchased power [2] 68 72 137
Gas purchased for resale [2] 245 243 433
Other operations and maintenance [2],[3] 658 626 626
Depreciation and amortization [2] 546 531 507
Other taxes [2] 300 292 277
Total operating expenses 2,420 2,346 2,980
Other income, net [4] 2 24 55
Interest charges, net of AFUDC [2] 276 250 220
Income tax expense (benefit) [2] 80 79 132
Deferred cost of employee benefit plans, net of tax [4] 0 1 (1)
Comprehensive Income Attributable to Noncontrolling Interest [4] 23 21 20
Comprehensive Income (Loss) Available (Attributable) to Common Shareholder 376 357 485
Capital expenditures 1,105 957 697
Total assets 17,000 15,900  
Corporate and Other      
Segment Reporting Information [Line Items]      
Operating Revenue 0 0 0
Fuel used in electric generation [2] 0 0 0
Purchased power [2] 0 0 0
Gas purchased for resale [2] 0 0 0
Other operations and maintenance [2],[3] 59 (24) 4
Depreciation and amortization [2] 0 0 0
Other taxes [2] 0 0 0
Total operating expenses 59 (24) 4
Other income, net [4] (3) 0 0
Interest charges, net of AFUDC [2] 0 0 0
Income tax expense (benefit) [2] (15) 6 (1)
Deferred cost of employee benefit plans, net of tax [4] 0 0 0
Comprehensive Income Attributable to Noncontrolling Interest [4] 0 0 0
Comprehensive Income (Loss) Available (Attributable) to Common Shareholder (47) 18 (3)
Capital expenditures 0 0 $ 0
Total assets $ 0 $ 0  
[1] See Note 16 for amounts attributable to affiliates.
[2] The significant expense categories and amounts in the segment information presented above align with the segment-level information that is regularly provided to DESC’s CODM.
[3] Includes impairment of assets and other charges.
[4] Items designated are other segment items for each reportable segment.
v3.25.0.1
Utility Plant and Nonutility Property - Property, Plant and Equipment (Details) - USD ($)
$ in Millions
Dec. 31, 2024
Dec. 31, 2023
Generation [Member]    
Property Plant And Equipment [Line Items]    
Utility plant in service $ 6,635 $ 6,322
Transmission [Member]    
Property Plant And Equipment [Line Items]    
Utility plant in service 2,342 2,272
Distribution [Member]    
Property Plant And Equipment [Line Items]    
Utility plant in service 6,311 5,901
Storage [Member]    
Property Plant And Equipment [Line Items]    
Utility plant in service 79 79
General and other    
Property Plant And Equipment [Line Items]    
Utility plant in service 651 644
Intangible    
Property Plant And Equipment [Line Items]    
Utility plant in service 282 282
Construction Work In Progress    
Property Plant And Equipment [Line Items]    
Utility plant in service 899 606
Nuclear Fuel    
Property Plant And Equipment [Line Items]    
Utility plant in service 570 609
Total Gross Utility Plant    
Property Plant And Equipment [Line Items]    
Utility plant in service 17,769 16,715
Gross Nonutility Property    
Property Plant And Equipment [Line Items]    
Gross nonutility property $ 16 $ 25
v3.25.0.1
Utility Plant and Nonutility Property - Schedule of Jointly Owned Utility Plants (Details) - Summer Unit 1 - USD ($)
$ in Millions
Dec. 31, 2024
Dec. 31, 2023
Property Plant And Equipment [Line Items]    
Jointly owned utility plant, proportionate ownership share 66.70% 66.70%
Plant in service, jointly owned utility plant $ 1,600 $ 1,600
Accumulated depreciation, jointly owned utility plant 784 772
Construction work in progress, jointly owned utility plant $ 58 $ 88
v3.25.0.1
Utility Plant and Nonutility Property (Narrative) (Details) - USD ($)
$ in Millions
Dec. 31, 2024
Dec. 31, 2023
Utility Plant And Non Utility Property [Line Items]    
Amounts due from Santee Cooper for share of direct expenses $ 104 $ 97
Summer [Member]    
Utility Plant And Non Utility Property [Line Items]    
Amounts due from Santee Cooper for share of direct expenses $ 36 $ 50
v3.25.0.1
Affiliated and Related Party Transactions (Schedule of Affiliated Transactions - Income Statement) (Detail) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2024
Dec. 31, 2023
Dec. 31, 2022
Related Party Transaction [Line Items]      
Operating Revenues – Electric from sales to affiliate $ 7 $ 4 $ 4
Operating Revenues – Gas from sales to affiliate 1 1 1
Operating Expenses – Other taxes from affiliate 8 8 8
Solar Affiliates [Member]      
Related Party Transaction [Line Items]      
Purchases from affiliate 8 13 14
Related Party | DES      
Related Party Transaction [Line Items]      
Direct and allocated costs [1] $ 222 $ 222 $ 212
[1] Includes capitalized expenditures of $57 million, $59 million and $48 million for the years ended December 31, 2024, 2023 and 2022, respectively.
v3.25.0.1
Affiliated and Related Party Transactions (Schedule of Affiliated Transactions - Income Statement) (Parenthetical) (Detail) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2024
Dec. 31, 2023
Dec. 31, 2022
DES      
Related Party Transaction [Line Items]      
Capitalized expenditures $ 57 $ 59 $ 48
v3.25.0.1
Affiliated and Related Party Transactions (Schedule of Affiliated Transactions - Balance Sheet) (Detail) - USD ($)
$ in Millions
Dec. 31, 2024
Dec. 31, 2023
Related Party Transaction [Line Items]    
Affiliated and related party payables and other $ 194 $ 163
Derivative assets with affiliates [1] 48 33
DES | Related Party    
Related Party Transaction [Line Items]    
Affiliated and related party payables and other 19 18
SCANA Corporation | Related Party    
Related Party Transaction [Line Items]    
Affiliated and related party payables and other $ 7 7
PSNC | Related Party    
Related Party Transaction [Line Items]    
Affiliated and related party payables and other   $ 13
[1] Includes amounts recorded in current derivative assets of $4 million and $2 million as of December 31, 2024 and 2023, respectively, and amounts recorded in noncurrent derivative assets of $44 million and $31 million as of December 31, 2024 and 2023, respectively.
v3.25.0.1
Affiliated and Related Party Transactions (Schedule of Affiliated Transactions - Balance Sheet) (Parenthetical) (Detail) - USD ($)
$ in Millions
Dec. 31, 2024
Dec. 31, 2023
Related Party Transaction [Line Items]    
Derivative assets with affiliates [1] $ 48 $ 33
Current Derivative Assets [Member]    
Related Party Transaction [Line Items]    
Derivative assets with affiliates 4 2
Noncurrent Derivative Assets [Member]    
Related Party Transaction [Line Items]    
Derivative assets with affiliates $ 44 $ 31
[1] Includes amounts recorded in current derivative assets of $4 million and $2 million as of December 31, 2024 and 2023, respectively, and amounts recorded in noncurrent derivative assets of $44 million and $31 million as of December 31, 2024 and 2023, respectively.
v3.25.0.1
Other Income (Expense), Net (Components of Other Income (Expense), Net) (Detail) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2024
Dec. 31, 2023
Dec. 31, 2022
Income Statement [Abstract]      
Other income $ 12 $ 8 $ 10
Gains on sales of assets [1] 4 32 42
Other expense (19) (16) 2
Allowance for equity funds used during construction 2 0 1
Other income (expense), net [2] $ (1) $ 24 $ 55
[1] Includes amounts recognized in connection with the transfer of property, plant and equipment to satisfy litigation in 2023 and 2022. See Note 12 for additional information.
[2] Items designated are other segment items for each reportable segment.
v3.25.0.1
Other Income (Expense), Net (Narrative) (Details) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2023
Dec. 31, 2022
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]    
Total cash consideration $ 12 $ 20
Net gain on sale of assets   20
Net gain on sale of assets, after tax   $ 15
Corporate and Other    
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]    
Net gain on sale of assets 11  
Net gain on sale of assets, after tax $ 8