DOMINION ENERGY SOUTH CAROLINA, INC., 10-Q filed on 5/1/2025
Quarterly Report
v3.25.1
Document and Entity Information - shares
 3 Months Ended
Mar. 31, 2025
Apr. 25, 2025
Cover [Abstract]    
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  
Document Type 10-Q  
Document Fiscal Year Focus 2025  
Document Fiscal Period Focus Q1  
Amendment Flag false  
Entity Emerging Growth Company false  
Entity Small Business false  
Entity Common Stock, Shares Outstanding   40,296,147
Entity Current Reporting Status Yes  
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 Incorporation, State or Country Code SC  
Document Quarterly Report true  
Document Transition Report false  
Entity Interactive Data Current Yes  
Document Period End Date Mar. 31, 2025  
v3.25.1
Consolidated Balance Sheets (Unaudited) - USD ($)
$ in Millions
Mar. 31, 2025
Dec. 31, 2024
ASSETS    
Utility plant in service $ 16,488 $ 16,300
Accumulated depreciation and amortization (5,809) (5,761)
Construction work in progress 913 899
Nuclear fuel, net of accumulated amortization 215 224
Utility plant, net 11,807 11,662
Nonutility Property and Investments:    
Nonutility property, net of accumulated depreciation 16 16
Assets held in trust, nuclear decommissioning 269 268
Nonutility property and investments, net 285 284
Current Assets:    
Cash and cash equivalents 7 0
Customer, net of allowance for uncollectible accounts of $8 and $6 403 423
Receivables, other 87 104
Inventories (at average cost):    
Fuel 88 83
Gas storage 19 22
Materials and supplies 214 211
Prepayments 81 91
Derivative assets [1] 73 63
Regulatory assets 340 299
Other current assets 15 16
Total current assets 1,330 1,316
Deferred Debits and Other Assets:    
Derivative assets [1] 206 309
Regulatory assets 3,362 3,342
Affiliated receivables 26 26
Other 102 102
Total deferred debits and other assets 3,696 3,779
Total assets 17,118 17,041
CAPITALIZATION AND LIABILITIES    
Common Stock - no par value 4,338 4,088
Retained earnings 831 689
Accumulated other comprehensive loss (1) (1)
Total common equity 5,168 4,776
Noncontrolling interest 214 206
Total equity 5,382 4,982
Long-term debt, net 4,666 4,220
Affiliated long-term debt 230 230
Finance leases 2 2
Total long-term debt 4,898 4,452
Total capitalization 10,280 9,434
Current Liabilities:    
Short-term borrowings 210 250
Securities due within one year 2 2
Accounts payable 201 273
Affiliated and related party payables 623 995
Customer deposits and customer prepayments 75 82
Taxes accrued 73 254
Interest accrued 90 83
Regulatory liabilities 227 201
Derivative liabilities 1 0
Other 159 201
Total current liabilities 1,661 2,341
Deferred Credits and Other Liabilities:    
Deferred income taxes and investment tax credits 1,447 1,409
Asset retirement obligations 1,142 1,139
Pension and other postretirement benefits 109 109
Derivative liabilities 6 1
Regulatory liabilities 2,361 2,488
Other 112 120
Total deferred credits and other liabilities 5,177 5,266
Commitments and Contingencies
Total capitalization and liabilities 17,118 17,041
Related Party    
Current Assets:    
Affiliated and related party $ 3 $ 4
[1] See Note 12 for amounts attributable to affiliates.
v3.25.1
Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($)
shares in Millions, $ in Millions
Mar. 31, 2025
Dec. 31, 2024
Utility plant, net $ 11,807 $ 11,662
Receivables, customer, allowance for uncollectible accounts 8 6
Total current assets 1,330 1,316
Total deferred debits and other assets $ 3,696 $ 3,779
Common stock, par value $ 0 $ 0
Common stock, shares outstanding 40.3 40.3
Variable Interest Entity, Primary Beneficiary [Member]    
Utility plant, net $ 822 $ 824
Total current assets 83 79
Total deferred debits and other assets $ 27 $ 25
v3.25.1
Consolidated Statements of Comprehensive Income (Unaudited) - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2025
Mar. 31, 2024
Income Statement [Abstract]    
Operating Revenue [1] $ 986 $ 775
Operating Expenses:    
Fuel used in electric generation [2] 204 145
Purchased power [1],[2] 22 10
Gas purchased for resale [2] 126 79
Other operations and maintenance 131 122
Other operations and maintenance - affiliated suppliers 43 41
Depreciation and amortization [2] 140 136
Other taxes [1],[2] 82 78
Total operating expenses 748 611
Operating income 238 164
Other income (expense), net [3] 3 1
Interest charges, net of AFUDC of $6 and $4 [1] 71 67
Income before income tax expense 170 98
Income tax expense [2] 20 18
Net Income and Other Comprehensive Income 150 80
Comprehensive Income Attributable to Noncontrolling Interest [3] 8 6
Comprehensive Income Available to Common Shareholder $ 142 $ 74
[1] See Note 12 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.
v3.25.1
Consolidated Statements of Comprehensive Income (Unaudited) (Parenthetical) - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2025
Mar. 31, 2024
Income Statement [Abstract]    
Allowance for funds used during construction $ 6 $ 4
v3.25.1
Consolidated Statements of Cash Flows (Unaudited) - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2025
Mar. 31, 2024
Operating Activities    
Net income $ 150 $ 80
Adjustments to reconcile net income to net cash provided by operating activities:    
Deferred income taxes, net 38 5
Depreciation and amortization 140 136
Amortization of nuclear fuel 10 9
Other adjustments 5 0
Changes in certain assets and liabilities:    
Receivables 29 45
Receivables - affiliated and related party 1 1
Inventories (4) (1)
Prepayments and deposits, net 3 2
Regulatory assets (98) 79
Regulatory liabilities (100) 41
Accounts payable (34) (18)
Accounts payable - affiliated and related party 12 43
Taxes accrued (181) (177)
Interest accrued 7 2
Net realized and unrealized changes related to commodity derivative activities 98 (78)
Pension and other postretirement benefits 0 (1)
Other assets and liabilities (22) (2)
Net cash provided by operating activities 54 166
Investing Activities    
Property additions and construction expenditures (297) (268)
Proceeds from investments and sales or disposals of assets, including asset retirement costs (23) (13)
Purchase of investments 0 (5)
Other 1 0
Net cash used in investing activities (319) (286)
Financing Activities    
Proceeds from issuance of debt 450 0
Dividend to parent 0 (62)
Contribution from parent 250 0
Short-term borrowings, net (40) (44)
Short-term borrowings - affiliated, net (384) 230
Other (4) (1)
Net cash provided by financing activities 272 123
Net increase in cash, restricted cash and equivalents 7 3
Cash, restricted cash and equivalents at beginning of period [1] 0 1
Cash, restricted cash and equivalents at end of period [1] 7 4
Significant noncash investing and financing activities:    
Accrued construction expenditures 73 56
Operating leases [2] $ 4 $ 0
[1] At March 31, 2025, December 31, 2024, March 31, 2024 and December 31, 2023 there were no restricted cash and equivalents balances.
[2] Finance leases entered into, if any, were inconsequential for all periods presented.
v3.25.1
Consolidated Statements of Cash Flows (Unaudited) (Parenthetical) - USD ($)
$ in Millions
Mar. 31, 2025
Dec. 31, 2024
Mar. 31, 2024
Dec. 31, 2023
Statement of Cash Flows [Abstract]        
Restricted cash and equivalents $ 0 $ 0 $ 0 $ 0
v3.25.1
Consolidated Statements of Changes in Common Equity (Unaudited) - USD ($)
shares in Millions, $ in Millions
Total
Common Stock
Retained Earnings
AOCI
Noncontrolling Interest
Beginning balance at Dec. 31, 2023 $ 4,862 $ 4,088 $ 592 $ (1) $ 183
Beginning balance (in shares) at Dec. 31, 2023   40      
Total comprehensive income available to common shareholder 80   74   6
Dividend to parent (62)   (62)    
Ending balance at Mar. 31, 2024 4,880 $ 4,088 604 (1) 189
Ending balance (in shares) at Mar. 31, 2024   40      
Beginning balance at Dec. 31, 2024 4,982 $ 4,088 689 (1) 206
Beginning balance (in shares) at Dec. 31, 2024   40      
Total comprehensive income available to common shareholder 150   142   8
Capital contribution from parent 250 $ 250      
Ending balance at Mar. 31, 2025 $ 5,382 $ 4,338 $ 831 $ (1) $ 214
Ending balance (in shares) at Mar. 31, 2025   40      
v3.25.1
Pay vs Performance Disclosure - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2025
Mar. 31, 2024
Pay vs Performance Disclosure    
Net Income (Loss) $ 142 $ 74
v3.25.1
Insider Trading Arrangements
 3 Months Ended
Mar. 31, 2025
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
v3.25.1
Summary of Significant Accounting Policies
 3 Months Ended
Mar. 31, 2025
Accounting Policies [Abstract]  
Summary of Significant Accounting Policies

1. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

Basis of Consolidation and Variable Interest Entities

DESC has determined that it has a controlling financial interest in each of GENCO and Fuel Company (which are considered to be VIEs) and, accordingly, DESC’s Consolidated Financial Statements include, after eliminating intercompany balances and transactions, the accounts of DESC, GENCO and Fuel Company. See Note 2 to the Consolidated Financial Statements included in DESC’s Annual Report on Form 10-K for the year ended December 31, 2024 for a description of GENCO and Fuel Company.

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 12 for amounts attributable to affiliates.

Significant Accounting Policies

There have been no significant changes from Note 2 to the Consolidated Financial Statements in DESC’s Annual Report on Form 10-K for the year ended December 31, 2024.
v3.25.1
Rate and Other Regulatory Matters
 3 Months Ended
Mar. 31, 2025
Regulated Operations [Abstract]  
Rate and Other Regulatory Matters

2. 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

Other than the following matters, there have been no significant developments regarding the pending regulatory matters disclosed in Note 3 to the Consolidated Financial Statements in DESC’s Annual Report on Form 10-K for the year ended December 31, 2024.

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 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. In March 2025, DESC and the South Carolina Office of Regulatory Staff filed a settlement agreement with the South Carolina Commission for approval to make certain adjustments to the February 2025 filing that would result in an inconsequential change to the proposed annual increase. In April 2025, the South Carolina Commission approved the settlement agreement, with rates effective with the first billing cycle of May 2025.

Electric - Transmission Project

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. In April 2025, the South Carolina Commission approved the application.

Electric – Other

DESC has approval for a DSM rider through which it recovers expenditures related to its DSM programs. 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. In April 2025, the South Carolina Commission approved the request, effective with the first billing cycle of May 2025.

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 2025, DESC requested that the South Carolina Commission approve an adjustment to this rider to decrease annual revenue by $13 million. In April 2025, the South Carolina Commission approved the request.

 

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.

 

 

 

March 31,

 

 

December 31,

 

(millions)

 

2025

 

 

2024

 

Regulatory assets:

 

 

 

 

 

 

NND Project costs(1)

 

$

138

 

 

$

138

 

AROs(2)

 

 

6

 

 

 

8

 

Deferred employee benefit plan costs(3)

 

 

5

 

 

 

8

 

Other unrecovered plant(4)

 

 

18

 

 

 

18

 

DSM programs(5)

 

 

23

 

 

 

24

 

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

 

 

92

 

 

 

35

 

Other

 

 

58

 

 

 

68

 

Regulatory assets - current

 

 

340

 

 

 

299

 

NND Project costs(1)

 

 

1,776

 

 

 

1,811

 

AROs(2)

 

 

704

 

 

 

695

 

Deferred employee benefit plan costs(3)

 

 

96

 

 

 

94

 

Interest rate hedges(7)

 

 

167

 

 

 

167

 

Other unrecovered plant(4)

 

 

94

 

 

 

89

 

DSM programs(5)

 

 

48

 

 

 

49

 

Environmental remediation costs(8)

 

 

42

 

 

 

42

 

Deferred storm damage costs(9)

 

 

77

 

 

 

76

 

Deferred transmission operating costs(10)

 

 

71

 

 

 

72

 

Derivatives(11)

 

 

94

 

 

 

95

 

Other(12)

 

 

193

 

 

 

152

 

Regulatory assets - noncurrent

 

 

3,362

 

 

 

3,342

 

Total regulatory assets

 

$

3,702

 

 

$

3,641

 

Regulatory liabilities:

 

 

 

 

 

 

Monetization of guaranty settlement(13)

 

$

67

 

 

$

67

 

Income taxes refundable through future rates(14)

 

 

17

 

 

 

24

 

Reserve for refunds to electric utility customers(15)

 

 

67

 

 

 

73

 

Derivatives(11)

 

 

44

 

 

 

27

 

Other

 

 

32

 

 

 

10

 

Regulatory liabilities - current

 

 

227

 

 

 

201

 

Monetization of guaranty settlement(13)

 

 

552

 

 

 

568

 

Income taxes refundable through future rates(14)

 

 

838

 

 

 

820

 

Asset removal costs(16)

 

 

597

 

 

 

598

 

Reserve for refunds to electric utility customers(15)

 

 

146

 

 

 

161

 

Derivatives(11)

 

 

223

 

 

 

328

 

Other

 

 

5

 

 

 

13

 

Regulatory liabilities - noncurrent

 

 

2,361

 

 

 

2,488

 

Total regulatory liabilities

 

$

2,588

 

 

$

2,689

 

 

(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 reflects amounts related to the EPA’s May 2024 final rule concerning CCR as discussed in Note 10.
(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. Based on rates currently in effect, DESC expects to recover certain deferred benefit costs through utility rates over average service periods of participating employees, which is approximately 11 years. DESC expects to recover other deferred pension costs through utility rates over periods through 2044.
(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. The majority of unamortized amounts are included in rate base and are earning a current return.
(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 10 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).
(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.
v3.25.1
Operating Revenue
 3 Months Ended
Mar. 31, 2025
Revenues [Abstract]  
Operating Revenue

3. OPERATING REVENUE

DESC’s revenue consists of the following:

 

Three Months Ended March 31,

2025

 

 

2024

 

(millions)

Electric

 

 

Gas

 

 

Electric

 

 

Gas

 

Customer class:

 

 

 

 

 

 

 

 

 

 

 

Residential

$

371

 

 

$

151

 

 

$

283

 

 

$

117

 

Commercial

 

228

 

 

 

54

 

 

 

188

 

 

 

41

 

Industrial

 

109

 

 

 

27

 

 

 

87

 

 

 

18

 

Other

 

32

 

 

 

8

 

 

 

28

 

 

 

6

 

Revenues from contracts with customers

 

740

 

 

 

240

 

 

 

586

 

 

 

182

 

Other revenues

 

6

 

 

 

—

 

 

 

7

 

 

 

—

 

Total Operating Revenues

$

746

 

 

$

240

 

 

$

593

 

 

$

182

 

 

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 $5 million and $6 million at March 31, 2025 and December 31, 2024, respectively. During both the three months ended March 31, 2025 and 2024, DESC recognized revenue of $3 million 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.

 

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

 

 

 

Regulatory Assets

 

(millions)

 

March 31, 2025

 

 

December 31, 2024

 

Beginning balance

 

$

10

 

 

$

11

 

Additional costs

 

 

4

 

 

 

—

 

Amortization

 

 

—

 

 

 

(1

)

Ending balance

 

$

14

 

 

$

10

 
v3.25.1
Equity
 3 Months Ended
Mar. 31, 2025
Equity [Abstract]  
Equity

4. 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.

There have been no material changes to the dividend restrictions affecting DESC described in Note 5 to the Consolidated Financial Statements in DESC’s Annual Report on Form 10-K for the year ended December 31, 2024.

During the first quarter of 2025, DESC received equity contributions of $250 million from Dominion Energy. DESC primarily used these funds for working capital needs including reducing short-term debt.
v3.25.1
Long-Term and Short-Term Debt
 3 Months Ended
Mar. 31, 2025
Debt Disclosure [Abstract]  
Long-Term and Short-Term Debt

5. LONG-TERM AND SHORT-TERM DEBT

DESC’s short-term financing is supported through its access as co-borrower to Dominion Energy’s $7.0 billion joint revolving credit facility, as amended April 2025. The credit facility can be used for working capital, as support for the combined commercial paper programs of the borrowers under the credit facility and for other general corporate purposes. Other than the items discussed below, there have been no significant changes from Note 6 to the Consolidated Financial Statements in DESC’s Annual Report on Form 10-K for the year ended December 31, 2024.

At March 31, 2025, DESC’s share of commercial paper and letters of credit outstanding under its joint credit facility with Dominion Energy was as follows:

 

(millions)

 

Maximum Facility Sub-Limit

 

 

Outstanding
Commercial Paper

 

 

Outstanding
Letters of Credit

 

Joint revolving credit facility(1)

 

$

1,000

 

 

$

210

 

 

$

—

 

 

(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 March 31, 2025, the sub-limit for DESC was $500 million. In April 2025, the sub-limit was increased up to $1.0 billion. If DESC has liquidity needs in excess of its sub-limit, the sub-limit may be changed provided that it does not exceed $1.0 billion or such needs may be satisfied through short-term borrowings from Dominion Energy. This credit facility, as amended in April 2025, matures in April 2030, with the potential to be extended by the borrowers to April 2032. The credit facility can be used to support bank borrowings and the issuance of commercial paper, as well as to support up to $3.0 billion (or the sub-limit, whichever is less) of letters of credit.

In March 2025, FERC granted DESC authority through March 2027 to issue short-term indebtedness (pursuant to Section 204 of the Federal Power Act) in amounts not to exceed $1.8 billion outstanding with maturity dates of one year or less. At March 31, 2025, DESC had issued $210 million in commercial paper supported by its joint revolving credit facility with Dominion Energy as disclosed above and had drawn on $227 million of its intercompany credit facility with Dominion Energy, as permitted by this FERC authorization. In addition, in March 2025, FERC granted GENCO authority through March 2027 to issue short-term indebtedness not to exceed $300 million outstanding with maturity dates of one year or less. At March 31, 2025, GENCO had drawn on $63 million of its intercompany credit facility with Dominion Energy, as permitted by this FERC authorization.

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 March 31, 2025 and December 31, 2024, DESC, GENCO and Fuel Company collectively had borrowings outstanding under these agreements totaling $558 million and $942 million, respectively, which are recorded in affiliated and related party payables in DESC’s Consolidated Balance Sheets. Interest charges associated with these agreements were $11 million and $10 million for the three months ended March 31, 2025 and 2024, respectively.

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.
v3.25.1
Income Taxes
 3 Months Ended
Mar. 31, 2025
Income Tax Disclosure [Abstract]  
Income Taxes

6. INCOME TAXES

 

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

 

Three Months Ended March 31,

 

2025

 

 

2024

 

U.S. statutory rate

 

 

21.0

%

 

 

21.0

%

Increases (reductions) resulting from:

 

 

 

 

 

 

State taxes, net of federal benefit

 

 

10.8

 

 

 

3.9

 

Reversal of excess deferred income taxes

 

 

(2.4

)

 

 

(5.3

)

Allowance for equity funds used during construction

 

 

—

 

 

 

(0.7

)

Remeasurements and settlements of uncertain tax positions

 

 

(17.5

)

 

—

 

Other, net

 

 

(0.2

)

 

—

 

Effective tax rate

 

 

11.7

%

 

 

18.9

%

As of March 31, 2025, DESC’s effective tax rate reflects an income tax net benefit of $18 million reflecting a $30 million remeasurement of an unrecognized tax benefit partially deferred to regulatory liabilities. See Note 7 to the Consolidated Financial Statements in DESC's Annual Report on Form 10-K for the year ended December 31, 2024, for a discussion of these unrecognized tax benefits.
v3.25.1
Derivative Financial Instruments
 3 Months Ended
Mar. 31, 2025
Derivative Instruments and Hedging Activities Disclosure [Abstract]  
Derivative Financial Instruments

7. DERIVATIVE FINANCIAL INSTRUMENTS

DESC’s accounting policies, objectives, and strategies for using derivative instruments are discussed in Note 2 in the Consolidated Financial Statements in DESC’s Annual Report on Form 10-K for the year ended December 31, 2024. See Note 8 for further information about fair value measurements and associated valuation methods for derivatives.

Cash collateral, as presented in the table below, is used 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 March 31, 2025 and December 31, 2024, DESC would have been required to post $2 million and $1 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 March 31, 2025 and December 31, 2024 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 March 31, 2025 and December 31, 2024 was $2 million and $1 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:

 

 

March 31, 2025

 

 

December 31, 2024

 

 

 

Gross Amounts Not Offset in the Consolidated
Balance Sheet

 

 

Gross Amounts Not Offset in the Consolidated
Balance Sheet

 

(millions)

 

Gross
Assets
Presented in the
Consolidated
Balance Sheet(1)

 

 

Financial
Instruments

 

 

Cash
Collateral
Received

 

 

Net
Amounts

 

 

Gross
Assets
Presented in the
Consolidated
Balance Sheet(1)

 

 

Financial
Instruments

 

 

Cash
Collateral
Received

 

 

Net
Amounts

 

Interest rate contracts:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Over-the-counter

 

$

2

 

 

$

—

 

 

$

—

 

 

$

2

 

 

$

2

 

 

$

—

 

 

$

—

 

 

$

2

 

Commodity contracts:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Over-the-counter

 

$

78

 

 

$

—

 

 

$

—

 

 

$

78

 

 

$

81

 

 

$

—

 

 

$

—

 

 

$

81

 

Total derivatives

 

$

80

 

 

$

—

 

 

$

—

 

 

$

80

 

 

$

83

 

 

$

—

 

 

$

—

 

 

$

83

 
(1)
Excludes derivative assets of $199 million and $289 million at March 31, 2025 and December 31, 2024, respectively, which are not subject to master netting or similar arrangements.

 

 

 

March 31, 2025

 

 

December 31, 2024

 

 

 

Gross Amounts Not Offset in the Consolidated
Balance Sheet

 

 

Gross Amounts Not Offset in the Consolidated
Balance Sheet

 

(millions)

 

Gross
Liabilities
Presented in the
Consolidated
Balance Sheet(1)

 

 

Financial
Instruments

 

 

Cash
Collateral
Paid

 

 

Net
Amounts

 

 

Gross
Liabilities
Presented in the
Consolidated
Balance Sheet(1)

 

 

Financial
Instruments

 

 

Cash
Collateral
Paid

 

 

Net
Amounts

 

Interest rate contracts:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Over-the-counter

 

$

2

 

 

$

—

 

 

$

—

 

 

$

2

 

 

$

1

 

 

$

—

 

 

$

—

 

 

$

1

 

Total derivatives

 

$

2

 

 

$

—

 

 

$

—

 

 

$

2

 

 

$

1

 

 

$

—

 

 

$

—

 

 

$

1

 
(1)
Excludes derivative liabilities of $5 million at March 31, 2025, which are not subject to master netting or similar arrangements. DESC did not have any derivative liabilities at December 31, 2024 which were not subject to master netting or similar arrangements.

Volumes

The following table presents the volume of derivative activity at March 31, 2025. These volumes are based on open derivative positions and represent the combined absolute value of their long and short positions.

 

Natural Gas (bcf):

 

Current

 

 

Noncurrent

 

Basis(1)

 

 

41

 

 

 

31

 

Electricity (MWh in millions):

 

 

 

 

 

 

Fixed price

 

 

2

 

 

 

22

 

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 tables present the fair values of derivatives and where they are presented in the Consolidated Balance Sheets:

 

 

Assets

 

Liabilities

 

(millions)

 

 

 

 

At March 31, 2025

 

 

 

 

Current derivatives not under cash flow hedge accounting

 

 

 

 

Commodity

$

73

 

$

—

 

Interest rate

 

—

 

 

1

 

Total current derivatives

$

73

 

$

1

 

Noncurrent derivatives not under cash flow hedge accounting

 

 

 

 

Commodity

$

204

 

$

5

 

Interest rate

 

2

 

 

1

 

Total noncurrent derivatives

 

206

 

 

6

 

Total derivatives

$

279

 

$

7

 

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

 

 

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)(2)

 

Three Months Ended March 31,

 

2025

 

 

2024

 

Derivative type and location of gains (losses):

 

 

 

 

 

 

Interest rate

 

$

—

 

 

$

—

 

Total

 

$

—

 

 

$

—

 

 

(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.
(2)
All derivatives in cash flow hedging relationships have settled and are being amortized over the life of the debt.

Derivatives Not Designated as Hedging Instruments

 

(millions)

 

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

 

Three Months Ended March 31,

 

2025

 

 

2024

 

Derivative type and location of gains (losses):

 

 

 

 

 

 

Commodity:

 

 

 

 

 

 

            Purchased power

 

$

3

 

 

$

(2

)

Interest rate:

 

 

 

 

 

 

Interest charges

 

 

(1

)

 

 

(1

)

Total

 

$

2

 

 

$

(3

)

 

(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.
v3.25.1
Fair Value Measurements, Including Derivatives
 3 Months Ended
Mar. 31, 2025
Fair Value Disclosures [Abstract]  
Fair Value Measurements, Including Derivatives

8. FAIR VALUE MEASUREMENTS, INCLUDING DERIVATIVES

DESC’s fair value measurements are made in accordance with the policies discussed in Note 2 to the Consolidated Financial Statements in DESC’s Annual Report on Form 10-K for the year ended December 31, 2024. See Note 7 in this report for further information about DESC’s derivatives and hedge accounting activities.

The following table presents DESC’s quantitative information about Level 3 fair value measurements at March 31, 2025. 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

 

$

199

 

 

Discounted cash flow

 

Market price (per MWh)

(3)

 

30-83

 

48

Physical options:

 

 

 

 

 

 

 

 

 

 

 

 

Natural gas(2)

 

 

76

 

 

Option model

 

Market price (per Dth)

(3)

 

3-8

 

4

 

 

 

 

 

 

 

Price volatility

(4)

 

11%-74%

 

44%

Total assets

 

$

275

 

 

 

 

 

 

 

 

 

 

Liabilities

 

 

 

 

 

 

 

 

 

 

 

 

Physical forwards:

 

 

 

 

 

 

 

 

 

 

 

 

Electricity

 

$

5

 

 

Discounted cash flow

 

Market price (per MWh)

(3)

 

30-81

 

50

Total liabilities

 

$

5

 

 

 

 

 

 

 

 

 

 

 

(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

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:

 

(millions)

 

Level 1

 

 

Level 2

 

 

Level 3

 

 

Total

 

At March 31, 2025

 

 

 

 

 

 

 

 

 

 

 

 

Assets

 

 

 

 

 

 

 

 

 

 

 

 

Derivatives:

 

 

 

 

 

 

 

 

 

 

 

 

Commodity

 

$

—

 

 

$

2

 

 

$

275

 

 

$

277

 

Interest rate

 

 

—

 

 

 

2

 

 

 

—

 

 

 

2

 

Investments:

 

 

 

 

 

 

 

 

 

 

 

 

Cash equivalents and other

 

 

29

 

 

 

—

 

 

 

—

 

 

 

29

 

Total assets

 

$

29

 

 

$

4

 

 

$

275

 

 

$

308

 

Liabilities

 

 

 

 

 

 

 

 

 

 

 

 

Derivatives:

 

 

 

 

 

 

 

 

 

 

 

 

Commodity

 

$

—

 

 

$

—

 

 

$

5

 

 

$

5

 

Interest rate

 

 

—

 

 

 

2

 

 

 

—

 

 

 

2

 

Total liabilities

 

$

—

 

 

$

2

 

 

$

5

 

 

$

7

 

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

 

 

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.

 

 

 

 

 

 

Three Months Ended March 31,

 

 

 

2025

 

 

2024

 

(millions)

 

 

 

 

 

 

Beginning balance

 

$

370

 

 

$

176

 

Total realized and unrealized gains (losses):

 

 

 

 

 

 

Included in earnings:

 

 

 

 

 

 

Purchased power

 

 

3

 

 

 

(2

)

Included in regulatory assets/liabilities

 

 

(89

)

 

 

70

 

Settlements

 

 

(14

)

 

 

2

 

Purchases

 

 

—

 

 

 

7

 

Ending balance

 

$

270

 

 

$

253

 

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 three months ended March 31, 2025 and 2024.

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:

 

 

 

March 31, 2025

 

 

December 31, 2024

 

(millions)

 

Carrying Amount

 

 

Estimated Fair Value(1)

 

 

Carrying Amount

 

 

Estimated Fair Value(1)

 

Long-term debt(2)

 

$

4,666

 

 

$

4,632

 

 

$

4,220

 

 

$

4,142

 

Affiliated long-term debt

 

 

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.
v3.25.1
Employee Benefit Plans
 3 Months Ended
Mar. 31, 2025
Retirement Benefits [Abstract]  
Employee Benefit Plans

9. EMPLOYEE BENEFIT PLANS

In DESC’s Consolidated Statements of Comprehensive Income, the service cost component of net periodic benefit (credit) cost is reflected in other operations and maintenance expense with the non-service cost components reflected in other income (expense). Components of net periodic benefit cost (credit) recorded by DESC were as follows:

 

(millions)

 

Pension Benefits

 

 

Other Postretirement Benefits

 

Three Months Ended March 31,

 

2025

 

 

2024

 

 

2025

 

 

2024

 

Service cost

 

$

2

 

 

$

2

 

 

$

—

 

 

$

—

 

Interest cost

 

 

9

 

 

 

8

 

 

 

2

 

 

 

2

 

Expected return on assets

 

 

(10

)

 

 

(9

)

 

 

—

 

 

 

—

 

Amortization of actuarial losses

 

 

1

 

 

 

2

 

 

 

(1

)

 

 

(1

)

Net periodic benefit cost

 

$

2

 

 

$

3

 

 

$

1

 

 

$

1

 

 

During the three months ended March 31, 2025, DESC made less than $1 million of contributions to its qualified pension plan. During the three months ended March 31, 2024, DESC made no contributions to its pension trust. DESC expects to make $3 million of minimum required contributions to its qualified defined benefit pension plans in 2025 and expects to receive reimbursement for such contributions from Santee Cooper. DESC recovers current pension costs through either a rate rider that may be adjusted annually for retail electric operations or through cost of service rates for gas operations.
v3.25.1
Commitments And Contingencies
 3 Months Ended
Mar. 31, 2025
Commitments and Contingencies Disclosure [Abstract]  
Commitments and Contingencies

10. 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 three months ended March 31, 2025 and 2024, DESC recorded less than $1 million and $6 million, respectively, of charges in aggregate for various personal injury or wrongful death cases. DESC’s Consolidated Balance Sheets at March 31, 2025 and December 31, 2024 include $19 million and $10 million, respectively, of insurance receivables and $16 million and $7 million of reserves, respectively, primarily related to personal injury or wrongful death cases.

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.

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.

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 BTA 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 in 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 March 31, 2025, 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. As discussed in Note 12 to the Consolidated Financial Statements in the Company's Annual Report on Form 10-K for the year ended December 31, 2024, DESC recorded adjustments in its AROs in 2024 in connection with this rule. The actual AROs related to CCRs may vary substantially from the estimates used to record the obligation.

Surety Bonds

At March 31, 2025, 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.

v3.25.1
Operating Segments
 3 Months Ended
Mar. 31, 2025
Segment Reporting [Abstract]  
Operating Segments

11. 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 is Dominion Energy’s 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 the three months ended March 31, 2025 and 2024, DESC reported an insignificant amount of specific items in the Corporate and Other segment.

 

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

 

Three Months Ended March 31,

 

Dominion Energy
South Carolina

 

 

Corporate
and Other

 

 

Consolidated
Total

 

(millions)

 

 

 

 

 

 

 

 

 

2025

 

 

 

 

 

 

 

 

 

Operating Revenue

 

$

986

 

 

$

—

 

 

$

986

 

Fuel used in electric generation(1)

 

 

204

 

 

 

—

 

 

 

204

 

Purchased power(1)

 

 

22

 

 

 

—

 

 

 

22

 

Gas purchased for resale(1)

 

 

126

 

 

 

—

 

 

 

126

 

Other operations and maintenance(1)

 

 

174

 

 

 

—

 

 

 

174

 

Depreciation and amortization(1)

 

 

140

 

 

 

—

 

 

 

140

 

Other taxes(1)

 

 

82

 

 

 

—

 

 

 

82

 

Total Operating Expenses

 

 

748

 

 

 

—

 

 

 

748

 

Other income (expense), net(2)

 

 

3

 

 

 

—

 

 

 

3

 

Interest charges, net of AFUDC(1)

 

 

71

 

 

 

—

 

 

 

71

 

Income tax expense(1)

 

 

18

 

 

 

2

 

 

 

20

 

Comprehensive Income Attributable to Noncontrolling Interest(2)

 

 

8

 

 

 

—

 

 

 

8

 

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

 

 

144

 

 

 

(2

)

 

 

142

 

Capital expenditures

 

 

297

 

 

 

—

 

 

 

297

 

Total assets (billions)

 

 

17.1

 

 

 

—

 

 

 

17.1

 

2024

 

 

 

 

 

 

 

 

 

Operating Revenue

 

$

775

 

 

$

—

 

 

$

775

 

Fuel used in electric generation(1)

 

 

145

 

 

 

—

 

 

 

145

 

Purchased power(1)

 

 

10

 

 

 

—

 

 

 

10

 

Gas purchased for resale(1)

 

 

79

 

 

 

—

 

 

 

79

 

Other operations and maintenance(1)

 

 

163

 

 

 

—

 

 

 

163

 

Depreciation and amortization(1)

 

 

136

 

 

 

—

 

 

 

136

 

Other taxes(1)

 

 

78

 

 

 

—

 

 

 

78

 

Total Operating Expenses

 

 

611

 

 

 

—

 

 

 

611

 

Other income (expense), net(2)

 

 

1

 

 

 

—

 

 

 

1

 

Interest charges, net of AFUDC(1)

 

 

67

 

 

 

—

 

 

 

67

 

Income tax expense(1)

 

 

17

 

 

 

1

 

 

 

18

 

Comprehensive Income Attributable to Noncontrolling Interest(2)

 

 

6

 

 

 

—

 

 

 

6

 

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

 

 

75

 

 

 

(1

)

 

 

74

 

Capital expenditures

 

 

268

 

 

 

—

 

 

 

268

 
(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)
Items designated are other segment items for each reportable segment.
v3.25.1
Affiliated and Related Party Transactions
 3 Months Ended
Mar. 31, 2025
Related Party Transactions [Abstract]  
Affiliated and Related Party Transactions

12. 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 (expense), 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 7 for additional information.

 

 

 

Three Months Ended March 31,

 

(millions)

 

2025

 

 

2024

 

Direct and allocated costs from DES(1)

 

$

62

 

 

$

53

 

Operating Revenues - Electric from sales to affiliate

 

 

1

 

 

 

1

 

Operating Expenses - Other taxes from affiliate

 

 

3

 

 

 

3

 

Purchases of electricity from solar affiliates

 

 

3

 

 

 

1

 

 

(1)
Includes capitalized expenditures of $19 million and $12 million for the three months ended March 31, 2025 and 2024, respectively.

 

(millions)

 

March 31, 2025

 

 

December 31, 2024

 

Payable to DES

 

$

19

 

 

$

19

 

Payable to SCANA Corporation

 

 

7

 

 

 

7

 

Derivative assets with affiliates(1)

 

 

33

 

 

 

48

 

 

(1)
Includes amounts recorded in current derivative assets of $6 million and $4 million as of March 31, 2025 and December 31, 2024, respectively, and amounts recorded in noncurrent derivative assets of $27 million and $44 million as of March 31, 2025 and December 31, 2024, respectively.

 

Borrowings from an affiliate are described in Note 5.

v3.25.1
Other Income (Expense), Net
 3 Months Ended
Mar. 31, 2025
Income Statement [Abstract]  
Other Income (Expense), Net

13. OTHER INCOME (EXPENSE), NET

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

 

 

 

Three Months Ended March 31,

 

(millions)

 

2025

 

 

2024

 

Other income

 

$

5

 

 

$

2

 

Gains on sales of assets

 

 

—

 

 

 

1

 

Other expense

 

 

(2

)

 

 

(5

)

Allowance for equity funds used during construction

 

 

—

 

 

 

3

 

Other income (expense), net

 

$

3

 

 

$

1

 

 
v3.25.1
Summary of Significant Accounting Policies (Policies)
 3 Months Ended
Mar. 31, 2025
Accounting Policies [Abstract]  
Basis of Consolidation and Variable Interest Entities

Basis of Consolidation and Variable Interest Entities

DESC has determined that it has a controlling financial interest in each of GENCO and Fuel Company (which are considered to be VIEs) and, accordingly, DESC’s Consolidated Financial Statements include, after eliminating intercompany balances and transactions, the accounts of DESC, GENCO and Fuel Company. See Note 2 to the Consolidated Financial Statements included in DESC’s Annual Report on Form 10-K for the year ended December 31, 2024 for a description of GENCO and Fuel Company.

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 12 for amounts attributable to affiliates.

Significant Accounting Policies

There have been no significant changes from Note 2 to the Consolidated Financial Statements in DESC’s Annual Report on Form 10-K for the year ended December 31, 2024.
Regulatory Matters Involving Potential Loss Contingencies

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.
v3.25.1
Rate and Other Regulatory Matters (Tables)
 3 Months Ended
Mar. 31, 2025
Regulated Operations [Abstract]  
Schedule of Regulatory Assets and Liabilities

 

 

March 31,

 

 

December 31,

 

(millions)

 

2025

 

 

2024

 

Regulatory assets:

 

 

 

 

 

 

NND Project costs(1)

 

$

138

 

 

$

138

 

AROs(2)

 

 

6

 

 

 

8

 

Deferred employee benefit plan costs(3)

 

 

5

 

 

 

8

 

Other unrecovered plant(4)

 

 

18

 

 

 

18

 

DSM programs(5)

 

 

23

 

 

 

24

 

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

 

 

92

 

 

 

35

 

Other

 

 

58

 

 

 

68

 

Regulatory assets - current

 

 

340

 

 

 

299

 

NND Project costs(1)

 

 

1,776

 

 

 

1,811

 

AROs(2)

 

 

704

 

 

 

695

 

Deferred employee benefit plan costs(3)

 

 

96

 

 

 

94

 

Interest rate hedges(7)

 

 

167

 

 

 

167

 

Other unrecovered plant(4)

 

 

94

 

 

 

89

 

DSM programs(5)

 

 

48

 

 

 

49

 

Environmental remediation costs(8)

 

 

42

 

 

 

42

 

Deferred storm damage costs(9)

 

 

77

 

 

 

76

 

Deferred transmission operating costs(10)

 

 

71

 

 

 

72

 

Derivatives(11)

 

 

94

 

 

 

95

 

Other(12)

 

 

193

 

 

 

152

 

Regulatory assets - noncurrent

 

 

3,362

 

 

 

3,342

 

Total regulatory assets

 

$

3,702

 

 

$

3,641

 

Regulatory liabilities:

 

 

 

 

 

 

Monetization of guaranty settlement(13)

 

$

67

 

 

$

67

 

Income taxes refundable through future rates(14)

 

 

17

 

 

 

24

 

Reserve for refunds to electric utility customers(15)

 

 

67

 

 

 

73

 

Derivatives(11)

 

 

44

 

 

 

27

 

Other

 

 

32

 

 

 

10

 

Regulatory liabilities - current

 

 

227

 

 

 

201

 

Monetization of guaranty settlement(13)

 

 

552

 

 

 

568

 

Income taxes refundable through future rates(14)

 

 

838

 

 

 

820

 

Asset removal costs(16)

 

 

597

 

 

 

598

 

Reserve for refunds to electric utility customers(15)

 

 

146

 

 

 

161

 

Derivatives(11)

 

 

223

 

 

 

328

 

Other

 

 

5

 

 

 

13

 

Regulatory liabilities - noncurrent

 

 

2,361

 

 

 

2,488

 

Total regulatory liabilities

 

$

2,588

 

 

$

2,689

 

 

(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 reflects amounts related to the EPA’s May 2024 final rule concerning CCR as discussed in Note 10.
(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. Based on rates currently in effect, DESC expects to recover certain deferred benefit costs through utility rates over average service periods of participating employees, which is approximately 11 years. DESC expects to recover other deferred pension costs through utility rates over periods through 2044.
(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. The majority of unamortized amounts are included in rate base and are earning a current return.
(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 10 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).
(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.
v3.25.1
Operating Revenue (Tables)
 3 Months Ended
Mar. 31, 2025
Revenue Recognition and Deferred Revenue [Abstract]  
Disaggregation of Revenue

DESC’s revenue consists of the following:

 

Three Months Ended March 31,

2025

 

 

2024

 

(millions)

Electric

 

 

Gas

 

 

Electric

 

 

Gas

 

Customer class:

 

 

 

 

 

 

 

 

 

 

 

Residential

$

371

 

 

$

151

 

 

$

283

 

 

$

117

 

Commercial

 

228

 

 

 

54

 

 

 

188

 

 

 

41

 

Industrial

 

109

 

 

 

27

 

 

 

87

 

 

 

18

 

Other

 

32

 

 

 

8

 

 

 

28

 

 

 

6

 

Revenues from contracts with customers

 

740

 

 

 

240

 

 

 

586

 

 

 

182

 

Other revenues

 

6

 

 

 

—

 

 

 

7

 

 

 

—

 

Total Operating Revenues

$

746

 

 

$

240

 

 

$

593

 

 

$

182

 

 
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)

 

March 31, 2025

 

 

December 31, 2024

 

Beginning balance

 

$

10

 

 

$

11

 

Additional costs

 

 

4

 

 

 

—

 

Amortization

 

 

—

 

 

 

(1

)

Ending balance

 

$

14

 

 

$

10

 
v3.25.1
Long-Term and Short-Term Debt (Tables)
 3 Months Ended
Mar. 31, 2025
Debt Disclosure [Abstract]  
Schedule of Line of Credit Facilities

At March 31, 2025, DESC’s share of commercial paper and letters of credit outstanding under its joint credit facility with Dominion Energy was as follows:

 

(millions)

 

Maximum Facility Sub-Limit

 

 

Outstanding
Commercial Paper

 

 

Outstanding
Letters of Credit

 

Joint revolving credit facility(1)

 

$

1,000

 

 

$

210

 

 

$

—

 

 

(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 March 31, 2025, the sub-limit for DESC was $500 million. In April 2025, the sub-limit was increased up to $1.0 billion. If DESC has liquidity needs in excess of its sub-limit, the sub-limit may be changed provided that it does not exceed $1.0 billion or such needs may be satisfied through short-term borrowings from Dominion Energy. This credit facility, as amended in April 2025, matures in April 2030, with the potential to be extended by the borrowers to April 2032. The credit facility can be used to support bank borrowings and the issuance of commercial paper, as well as to support up to $3.0 billion (or the sub-limit, whichever is less) of letters of credit.
v3.25.1
Income Taxes (Tables)
 3 Months Ended
Mar. 31, 2025
Income Tax Disclosure [Abstract]  
Schedule of Effective Income Tax Rate Reconciliation

Three Months Ended March 31,

 

2025

 

 

2024

 

U.S. statutory rate

 

 

21.0

%

 

 

21.0

%

Increases (reductions) resulting from:

 

 

 

 

 

 

State taxes, net of federal benefit

 

 

10.8

 

 

 

3.9

 

Reversal of excess deferred income taxes

 

 

(2.4

)

 

 

(5.3

)

Allowance for equity funds used during construction

 

 

—

 

 

 

(0.7

)

Remeasurements and settlements of uncertain tax positions

 

 

(17.5

)

 

—

 

Other, net

 

 

(0.2

)

 

—

 

Effective tax rate

 

 

11.7

%

 

 

18.9

%
v3.25.1
Derivative Financial Instruments (Tables)
 3 Months Ended
Mar. 31, 2025
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:

 

 

March 31, 2025

 

 

December 31, 2024

 

 

 

Gross Amounts Not Offset in the Consolidated
Balance Sheet

 

 

Gross Amounts Not Offset in the Consolidated
Balance Sheet

 

(millions)

 

Gross
Assets
Presented in the
Consolidated
Balance Sheet(1)

 

 

Financial
Instruments

 

 

Cash
Collateral
Received

 

 

Net
Amounts

 

 

Gross
Assets
Presented in the
Consolidated
Balance Sheet(1)

 

 

Financial
Instruments

 

 

Cash
Collateral
Received

 

 

Net
Amounts

 

Interest rate contracts:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Over-the-counter

 

$

2

 

 

$

—

 

 

$

—

 

 

$

2

 

 

$

2

 

 

$

—

 

 

$

—

 

 

$

2

 

Commodity contracts:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Over-the-counter

 

$

78

 

 

$

—

 

 

$

—

 

 

$

78

 

 

$

81

 

 

$

—

 

 

$

—

 

 

$

81

 

Total derivatives

 

$

80

 

 

$

—

 

 

$

—

 

 

$

80

 

 

$

83

 

 

$

—

 

 

$

—

 

 

$

83

 
(1)
Excludes derivative assets of $199 million and $289 million at March 31, 2025 and December 31, 2024, respectively, which are not subject to master netting or similar arrangements.
Offsetting Liabilities

 

 

March 31, 2025

 

 

December 31, 2024

 

 

 

Gross Amounts Not Offset in the Consolidated
Balance Sheet

 

 

Gross Amounts Not Offset in the Consolidated
Balance Sheet

 

(millions)

 

Gross
Liabilities
Presented in the
Consolidated
Balance Sheet(1)

 

 

Financial
Instruments

 

 

Cash
Collateral
Paid

 

 

Net
Amounts

 

 

Gross
Liabilities
Presented in the
Consolidated
Balance Sheet(1)

 

 

Financial
Instruments

 

 

Cash
Collateral
Paid

 

 

Net
Amounts

 

Interest rate contracts:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Over-the-counter

 

$

2

 

 

$

—

 

 

$

—

 

 

$

2

 

 

$

1

 

 

$

—

 

 

$

—

 

 

$

1

 

Total derivatives

 

$

2

 

 

$

—

 

 

$

—

 

 

$

2

 

 

$

1

 

 

$

—

 

 

$

—

 

 

$

1

 
(1)
Excludes derivative liabilities of $5 million at March 31, 2025, which are not subject to master netting or similar arrangements. DESC did not have any derivative liabilities at December 31, 2024 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 March 31, 2025. These volumes are based on open derivative positions and represent the combined absolute value of their long and short positions.

 

Natural Gas (bcf):

 

Current

 

 

Noncurrent

 

Basis(1)

 

 

41

 

 

 

31

 

Electricity (MWh in millions):

 

 

 

 

 

 

Fixed price

 

 

2

 

 

 

22

 

Interest rate(2) (in millions)

 

 

—

 

 

 

71

 

 

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

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

 

 

Assets

 

Liabilities

 

(millions)

 

 

 

 

At March 31, 2025

 

 

 

 

Current derivatives not under cash flow hedge accounting

 

 

 

 

Commodity

$

73

 

$

—

 

Interest rate

 

—

 

 

1

 

Total current derivatives

$

73

 

$

1

 

Noncurrent derivatives not under cash flow hedge accounting

 

 

 

 

Commodity

$

204

 

$

5

 

Interest rate

 

2

 

 

1

 

Total noncurrent derivatives

 

206

 

 

6

 

Total derivatives

$

279

 

$

7

 

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

 

 
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)(2)

 

Three Months Ended March 31,

 

2025

 

 

2024

 

Derivative type and location of gains (losses):

 

 

 

 

 

 

Interest rate

 

$

—

 

 

$

—

 

Total

 

$

—

 

 

$

—

 
(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.
(2)
All derivatives in cash flow hedging relationships have settled and are being amortized over the life of the debt.
Derivatives Not Designated as Hedging Instruments

Derivatives Not Designated as Hedging Instruments

 

(millions)

 

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

 

Three Months Ended March 31,

 

2025

 

 

2024

 

Derivative type and location of gains (losses):

 

 

 

 

 

 

Commodity:

 

 

 

 

 

 

            Purchased power

 

$

3

 

 

$

(2

)

Interest rate:

 

 

 

 

 

 

Interest charges

 

 

(1

)

 

 

(1

)

Total

 

$

2

 

 

$

(3

)

 

(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.
v3.25.1
Fair Value Measurements, Including Derivatives (Tables)
 3 Months Ended
Mar. 31, 2025
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 March 31, 2025. 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

 

$

199

 

 

Discounted cash flow

 

Market price (per MWh)

(3)

 

30-83

 

48

Physical options:

 

 

 

 

 

 

 

 

 

 

 

 

Natural gas(2)

 

 

76

 

 

Option model

 

Market price (per Dth)

(3)

 

3-8

 

4

 

 

 

 

 

 

 

Price volatility

(4)

 

11%-74%

 

44%

Total assets

 

$

275

 

 

 

 

 

 

 

 

 

 

Liabilities

 

 

 

 

 

 

 

 

 

 

 

 

Physical forwards:

 

 

 

 

 

 

 

 

 

 

 

 

Electricity

 

$

5

 

 

Discounted cash flow

 

Market price (per MWh)

(3)

 

30-81

 

50

Total liabilities

 

$

5

 

 

 

 

 

 

 

 

 

 

 

(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:

 

(millions)

 

Level 1

 

 

Level 2

 

 

Level 3

 

 

Total

 

At March 31, 2025

 

 

 

 

 

 

 

 

 

 

 

 

Assets

 

 

 

 

 

 

 

 

 

 

 

 

Derivatives:

 

 

 

 

 

 

 

 

 

 

 

 

Commodity

 

$

—

 

 

$

2

 

 

$

275

 

 

$

277

 

Interest rate

 

 

—

 

 

 

2

 

 

 

—

 

 

 

2

 

Investments:

 

 

 

 

 

 

 

 

 

 

 

 

Cash equivalents and other

 

 

29

 

 

 

—

 

 

 

—

 

 

 

29

 

Total assets

 

$

29

 

 

$

4

 

 

$

275

 

 

$

308

 

Liabilities

 

 

 

 

 

 

 

 

 

 

 

 

Derivatives:

 

 

 

 

 

 

 

 

 

 

 

 

Commodity

 

$

—

 

 

$

—

 

 

$

5

 

 

$

5

 

Interest rate

 

 

—

 

 

 

2

 

 

 

—

 

 

 

2

 

Total liabilities

 

$

—

 

 

$

2

 

 

$

5

 

 

$

7

 

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

 
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.

 

 

 

 

 

 

Three Months Ended March 31,

 

 

 

2025

 

 

2024

 

(millions)

 

 

 

 

 

 

Beginning balance

 

$

370

 

 

$

176

 

Total realized and unrealized gains (losses):

 

 

 

 

 

 

Included in earnings:

 

 

 

 

 

 

Purchased power

 

 

3

 

 

 

(2

)

Included in regulatory assets/liabilities

 

 

(89

)

 

 

70

 

Settlements

 

 

(14

)

 

 

2

 

Purchases

 

 

—

 

 

 

7

 

Ending balance

 

$

270

 

 

$

253

 
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:

 

 

 

March 31, 2025

 

 

December 31, 2024

 

(millions)

 

Carrying Amount

 

 

Estimated Fair Value(1)

 

 

Carrying Amount

 

 

Estimated Fair Value(1)

 

Long-term debt(2)

 

$

4,666

 

 

$

4,632

 

 

$

4,220

 

 

$

4,142

 

Affiliated long-term debt

 

 

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.
v3.25.1
Employee Benefit Plans (Tables)
 3 Months Ended
Mar. 31, 2025
Retirement Benefits [Abstract]  
Components of Net Periodic Benefit Cost (Credit) Components of net periodic benefit cost (credit) recorded by DESC were as follows:

 

(millions)

 

Pension Benefits

 

 

Other Postretirement Benefits

 

Three Months Ended March 31,

 

2025

 

 

2024

 

 

2025

 

 

2024

 

Service cost

 

$

2

 

 

$

2

 

 

$

—

 

 

$

—

 

Interest cost

 

 

9

 

 

 

8

 

 

 

2

 

 

 

2

 

Expected return on assets

 

 

(10

)

 

 

(9

)

 

 

—

 

 

 

—

 

Amortization of actuarial losses

 

 

1

 

 

 

2

 

 

 

(1

)

 

 

(1

)

Net periodic benefit cost

 

$

2

 

 

$

3

 

 

$

1

 

 

$

1

 
v3.25.1
Operating Segments (Tables)
 3 Months Ended
Mar. 31, 2025
Segment Reporting [Abstract]  
Schedule of Segment Reporting Information, by Segment

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

 

Three Months Ended March 31,

 

Dominion Energy
South Carolina

 

 

Corporate
and Other

 

 

Consolidated
Total

 

(millions)

 

 

 

 

 

 

 

 

 

2025

 

 

 

 

 

 

 

 

 

Operating Revenue

 

$

986

 

 

$

—

 

 

$

986

 

Fuel used in electric generation(1)

 

 

204

 

 

 

—

 

 

 

204

 

Purchased power(1)

 

 

22

 

 

 

—

 

 

 

22

 

Gas purchased for resale(1)

 

 

126

 

 

 

—

 

 

 

126

 

Other operations and maintenance(1)

 

 

174

 

 

 

—

 

 

 

174

 

Depreciation and amortization(1)

 

 

140

 

 

 

—

 

 

 

140

 

Other taxes(1)

 

 

82

 

 

 

—

 

 

 

82

 

Total Operating Expenses

 

 

748

 

 

 

—

 

 

 

748

 

Other income (expense), net(2)

 

 

3

 

 

 

—

 

 

 

3

 

Interest charges, net of AFUDC(1)

 

 

71

 

 

 

—

 

 

 

71

 

Income tax expense(1)

 

 

18

 

 

 

2

 

 

 

20

 

Comprehensive Income Attributable to Noncontrolling Interest(2)

 

 

8

 

 

 

—

 

 

 

8

 

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

 

 

144

 

 

 

(2

)

 

 

142

 

Capital expenditures

 

 

297

 

 

 

—

 

 

 

297

 

Total assets (billions)

 

 

17.1

 

 

 

—

 

 

 

17.1

 

2024

 

 

 

 

 

 

 

 

 

Operating Revenue

 

$

775

 

 

$

—

 

 

$

775

 

Fuel used in electric generation(1)

 

 

145

 

 

 

—

 

 

 

145

 

Purchased power(1)

 

 

10

 

 

 

—

 

 

 

10

 

Gas purchased for resale(1)

 

 

79

 

 

 

—

 

 

 

79

 

Other operations and maintenance(1)

 

 

163

 

 

 

—

 

 

 

163

 

Depreciation and amortization(1)

 

 

136

 

 

 

—

 

 

 

136

 

Other taxes(1)

 

 

78

 

 

 

—

 

 

 

78

 

Total Operating Expenses

 

 

611

 

 

 

—

 

 

 

611

 

Other income (expense), net(2)

 

 

1

 

 

 

—

 

 

 

1

 

Interest charges, net of AFUDC(1)

 

 

67

 

 

 

—

 

 

 

67

 

Income tax expense(1)

 

 

17

 

 

 

1

 

 

 

18

 

Comprehensive Income Attributable to Noncontrolling Interest(2)

 

 

6

 

 

 

—

 

 

 

6

 

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

 

 

75

 

 

 

(1

)

 

 

74

 

Capital expenditures

 

 

268

 

 

 

—

 

 

 

268

 
(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)
Items designated are other segment items for each reportable segment.
v3.25.1
Affiliated and Related Party Transactions (Tables)
 3 Months Ended
Mar. 31, 2025
Related Party Transactions [Abstract]  
Schedule of Affiliated Transactions Amounts expensed are primarily recorded in other operations and maintenance - affiliated suppliers and other income (expense), net in the Consolidated Statements of Comprehensive Income.

 

 

Three Months Ended March 31,

 

(millions)

 

2025

 

 

2024

 

Direct and allocated costs from DES(1)

 

$

62

 

 

$

53

 

Operating Revenues - Electric from sales to affiliate

 

 

1

 

 

 

1

 

Operating Expenses - Other taxes from affiliate

 

 

3

 

 

 

3

 

Purchases of electricity from solar affiliates

 

 

3

 

 

 

1

 

 

(1)
Includes capitalized expenditures of $19 million and $12 million for the three months ended March 31, 2025 and 2024, respectively.
Schedule of Affiliated Transactions

(millions)

 

March 31, 2025

 

 

December 31, 2024

 

Payable to DES

 

$

19

 

 

$

19

 

Payable to SCANA Corporation

 

 

7

 

 

 

7

 

Derivative assets with affiliates(1)

 

 

33

 

 

 

48

 

 

(1)
Includes amounts recorded in current derivative assets of $6 million and $4 million as of March 31, 2025 and December 31, 2024, respectively, and amounts recorded in noncurrent derivative assets of $27 million and $44 million as of March 31, 2025 and December 31, 2024, respectively.
v3.25.1
Other Income (Expense), Net (Tables)
 3 Months Ended
Mar. 31, 2025
Income Statement [Abstract]  
Components of Other Income (Expense), Net

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

 

 

 

Three Months Ended March 31,

 

(millions)

 

2025

 

 

2024

 

Other income

 

$

5

 

 

$

2

 

Gains on sales of assets

 

 

—

 

 

 

1

 

Other expense

 

 

(2

)

 

 

(5

)

Allowance for equity funds used during construction

 

 

—

 

 

 

3

 

Other income (expense), net

 

$

3

 

 

$

1

 

 
v3.25.1
Rate and Other Regulatory Matters (Narrative) (Detail)
$ in Millions
 1 Months Ended 3 Months Ended
Feb. 28, 2025
USD ($)
Jan. 31, 2025
USD ($)
Dec. 31, 2024
USD ($)
mi
kV
Sep. 30, 2024
USD ($)
Mar. 31, 2025
Feb. 27, 2025
USD ($)
Rate And Other Regulatory Matters [Line Items]            
Miles of Lines | mi     17      
Type of Line | kV     230      
Estimated electric transmission project cost     $ 55      
Regulatory asset recovery assessment end period         2078  
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 - Cost of Fuel [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
Reserve For Refunds To Electric Utility Customers [Member]            
Rate And Other Regulatory Matters [Line Items]            
Electric service customers recovery period         11 years  
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  
Asset Retirement Obligation Costs [Member]            
Rate And Other Regulatory Matters [Line Items]            
Recovery period of regulatory asset         105 years  
Environmental Remediation Costs [Member]            
Rate And Other Regulatory Matters [Line Items]            
Recovery period of regulatory asset         24 years  
Deferred Transmission Operating Costs [Member]            
Rate And Other Regulatory Matters [Line Items]            
Deferred transmission operating costs expected recovery period         2062  
Rider D S M [Member] | Electric - Other [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 $ 13          
v3.25.1
Rate and Other Regulatory Matters (Schedule of Regulatory Assets) (Detail) - USD ($)
$ in Millions
Mar. 31, 2025
Dec. 31, 2024
Regulatory Assets    
Regulatory assets, current $ 340 $ 299
Regulatory assets, noncurrent 3,362 3,342
Total regulatory assets 3,702 3,641
NND Project Costs [Member]    
Regulatory Assets    
Regulatory assets, current [1] 138 138
Regulatory assets, noncurrent [1] 1,776 1,811
Asset Retirement Obligation Costs [Member]    
Regulatory Assets    
Regulatory assets, current [2] 6 8
Regulatory assets, noncurrent [2] 704 695
Deferred Employee Benefit Plan Costs [Member]    
Regulatory Assets    
Regulatory assets, current [3] 5 8
Regulatory assets, noncurrent [3] 96 94
Interest Rate Hedges [Member]    
Regulatory Assets    
Regulatory assets, noncurrent [4] 167 167
Other Unrecovered Plant [Member]    
Regulatory Assets    
Regulatory assets, current [5] 18 18
Regulatory assets, noncurrent [5] 94 89
Demand Side Management Programs [Member]    
Regulatory Assets    
Regulatory assets, current [6] 23 24
Regulatory assets, noncurrent [6] 48 49
Cost of Fuel and Purchased Gas Under-Collections [Member]    
Regulatory Assets    
Regulatory assets, current [7] 92 35
Environmental Remediation Costs [Member]    
Regulatory Assets    
Regulatory assets, noncurrent [8] 42 42
Deferred Storm Damage Costs [Member]    
Regulatory Assets    
Regulatory assets, noncurrent [9] 77 76
Deferred Transmission Operating Costs [Member]    
Regulatory Assets    
Regulatory assets, noncurrent [10] 71 72
Derivatives [Member]    
Regulatory Assets    
Regulatory assets, noncurrent [11] 94 95
Other Regulatory Assets [Member]    
Regulatory Assets    
Regulatory assets, current 58 68
Regulatory assets, noncurrent [12] $ 193 $ 152
[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 reflects amounts related to the EPA’s May 2024 final rule concerning CCR as discussed in Note 10.
[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. Based on rates currently in effect, DESC expects to recover certain deferred benefit costs through utility rates over average service periods of participating employees, which is approximately 11 years. DESC expects to recover other deferred pension costs through utility rates over periods through 2044.
[4] 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.
[5] 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. The majority of unamortized amounts are included in rate base and are earning a current return.
[6] 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.
[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] 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 10 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 $2 million each year. Unamortized amounts are included in rate base and are earning a current return.
[10] Includes deferred depreciation and property taxes associated with certain transmission assets for which DESC expects future recovery from customers through 2062. Unamortized amounts are included in rate base and earning a current return.
[11] Represents changes in the fair value of derivatives, excluding separately presented interest rate hedges, that following settlement are expected to be recovered from or refunded to customers.
[12] Various other regulatory assets are expected to be recovered through rates over varying periods through 2078.
v3.25.1
Rate and Other Regulatory Matters (Schedule of Regulatory Liabilities) (Detail) - USD ($)
$ in Millions
Mar. 31, 2025
Dec. 31, 2024
Regulatory Liabilities    
Regulatory liability, current $ 227 $ 201
Regulatory liability, noncurrent 2,361 2,488
Total regulatory liabilities 2,588 2,689
Monetization Of Guaranty Settlement [Member]    
Regulatory Liabilities    
Regulatory liability, current [1] 67 67
Regulatory liability, noncurrent [1] 552 568
Income Taxes Refundable Through Future Rates [Member]    
Regulatory Liabilities    
Regulatory liability, current [2] 17 24
Regulatory liability, noncurrent [2] 838 820
Asset Removal Costs [Member]    
Regulatory Liabilities    
Regulatory liability, noncurrent [3] 597 598
Reserve For Refunds To Electric Utility Customers [Member]    
Regulatory Liabilities    
Regulatory liability, current [4] 67 73
Regulatory liability, noncurrent [4] 146 161
Derivatives [Member]    
Regulatory Liabilities    
Regulatory liability, current [5] 44 27
Regulatory liability, noncurrent [5] 223 328
Other Regulatory Liability [Member]    
Regulatory Liabilities    
Regulatory liability, current 32 10
Regulatory liability, noncurrent $ 5 $ 13
[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).
[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.
v3.25.1
Operating Revenue (Disaggregation of Revenue) (Detail) - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2025
Mar. 31, 2024
Total Operating Revenues [1] $ 986 $ 775
Electric Operations    
Operating revenue from contracts with customers 740 586
Other revenues 6 7
Total Operating Revenues 746 593
Gas Distribution    
Operating revenue from contracts with customers 240 182
Other revenues 0 0
Total Operating Revenues 240 182
Residential | Electric Operations    
Operating revenue from contracts with customers 371 283
Residential | Gas Distribution    
Operating revenue from contracts with customers 151 117
Commercial | Electric Operations    
Operating revenue from contracts with customers 228 188
Commercial | Gas Distribution    
Operating revenue from contracts with customers 54 41
Industrial | Electric Operations    
Operating revenue from contracts with customers 109 87
Industrial | Gas Distribution    
Operating revenue from contracts with customers 27 18
Other | Electric Operations    
Operating revenue from contracts with customers 32 28
Other | Gas Distribution    
Operating revenue from contracts with customers $ 8 $ 6
[1] See Note 12 for amounts attributable to affiliates.
v3.25.1
Operating Revenue (Narrative) (Detail) - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2025
Mar. 31, 2024
Dec. 31, 2024
Revenue from Contract with Customer [Abstract]      
Contract liability balances $ 5   $ 6
Revenue recognized from contract liability balances $ 3 $ 3  
v3.25.1
Operating Revenue (Balance and Activity Related to Contract Costs Deferred as Regulatory Assets) (Detail) - USD ($)
$ in Millions
 3 Months Ended 12 Months Ended
Mar. 31, 2025
Dec. 31, 2024
Revenues [Abstract]    
Beginning balance $ 10 $ 11
Additional costs 4 0
Amortization 0 (1)
Ending balance $ 14 $ 10
v3.25.1
Equity (Narrative) (Detail) - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2025
Mar. 31, 2024
Dec. 31, 2024
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
Contributions from parent $ 250 $ 0  
Dominion Energy      
Class Of Stock [Line Items]      
Contributions from parent $ 250    
v3.25.1
Long-Term and Short-Term Debt (Narrative) (Detail) - USD ($)
 1 Months Ended 3 Months Ended
Mar. 31, 2025
Jan. 31, 2025
Mar. 31, 2025
Mar. 31, 2024
Apr. 30, 2025
Dec. 31, 2024
Debt Instrument [Line Items]            
Commercial paper borrowing limit $ 1,800,000,000   $ 1,800,000,000      
Affiliated and related party payables and other $ 159,000,000   159,000,000     $ 201,000,000
Interest charges [1]     71,000,000 $ 67,000,000    
Maximum [Member]            
Debt Instrument [Line Items]            
Short term commercial paper maturity period 1 year          
Genco            
Debt Instrument [Line Items]            
Commercial paper borrowing limit $ 300,000,000   300,000,000      
Genco | Maximum [Member]            
Debt Instrument [Line Items]            
Short term commercial paper maturity period 1 year          
DESC | First mortgage bonds            
Debt Instrument [Line Items]            
Debt instrument, face amount   $ 450,000,000        
Interest rate percentage   5.30%        
Debt Instrument, Maturity Year   2035        
Dominion Energy            
Debt Instrument [Line Items]            
Affiliated and related party payables and other $ 558,000,000   558,000,000     942,000,000
Interest charges     11,000,000 $ 10,000,000    
Inter company credit facility maximum capacity 900,000,000   900,000,000      
Dominion Energy | Genco            
Debt Instrument [Line Items]            
Inter company credit facility maximum capacity 200,000,000   200,000,000      
Dominion Energy | Fuel company            
Debt Instrument [Line Items]            
Inter company credit facility maximum capacity 400,000,000   400,000,000      
Joint Revolving Credit Facility            
Debt Instrument [Line Items]            
Maximum Facility Sub-Limit [2] 1,000,000,000   1,000,000,000      
Joint Revolving Credit Facility | Commercial Paper            
Debt Instrument [Line Items]            
Debt instrument, face amount 210,000,000   210,000,000      
Joint Revolving Credit Facility | Dominion Energy | Subsequent Event            
Debt Instrument [Line Items]            
Maximum Facility Sub-Limit         $ 7,000,000,000  
Industrial Revenue Bonds            
Debt Instrument [Line Items]            
Debt instrument, face amount 68,000,000   68,000,000     $ 68,000,000
Intercompany Credit Facility            
Debt Instrument [Line Items]            
Line of credit, outstanding 227,000,000   227,000,000      
Intercompany Credit Facility | Genco            
Debt Instrument [Line Items]            
Line of credit, outstanding 63,000,000   63,000,000      
Letter of Credit            
Debt Instrument [Line Items]            
Maximum Facility Sub-Limit $ 3,000,000,000   $ 3,000,000,000      
[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] 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 March 31, 2025, the sub-limit for DESC was $500 million. In April 2025, the sub-limit was increased up to $1.0 billion. If DESC has liquidity needs in excess of its sub-limit, the sub-limit may be changed provided that it does not exceed $1.0 billion or such needs may be satisfied through short-term borrowings from Dominion Energy. This credit facility, as amended in April 2025, matures in April 2030, with the potential to be extended by the borrowers to April 2032. The credit facility can be used to support bank borrowings and the issuance of commercial paper, as well as to support up to $3.0 billion (or the sub-limit, whichever is less) of letters of credit.
v3.25.1
Long-Term and Short-Term Debt (Schedule of Line of Credit Facilities) (Detail) - Joint Revolving Credit Facility
Mar. 31, 2025
USD ($)
 [1]
Debt Instrument [Line Items]  
Maximum Facility Sub-Limit $ 1,000,000,000
Outstanding Commercial Paper 210,000,000
Outstanding Letters of Credit $ 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 March 31, 2025, the sub-limit for DESC was $500 million. In April 2025, the sub-limit was increased up to $1.0 billion. If DESC has liquidity needs in excess of its sub-limit, the sub-limit may be changed provided that it does not exceed $1.0 billion or such needs may be satisfied through short-term borrowings from Dominion Energy. This credit facility, as amended in April 2025, matures in April 2030, with the potential to be extended by the borrowers to April 2032. The credit facility can be used to support bank borrowings and the issuance of commercial paper, as well as to support up to $3.0 billion (or the sub-limit, whichever is less) of letters of credit.
v3.25.1
Long-Term and Short-Term Debt (Schedule of Line of Credit Facilities) (Parenthetical) (Detail) - USD ($)
 1 Months Ended
Apr. 30, 2025
Mar. 31, 2025
Minimum [Member] | Subsequent Event    
Debt Instrument [Line Items]    
Line of credit facility maturity date 2030-04  
Maximum [Member] | Subsequent Event    
Debt Instrument [Line Items]    
Line of credit facility maturity date 2032-04  
Joint Revolving Credit Facility    
Debt Instrument [Line Items]    
Maximum Facility Sub-Limit [1]   $ 1,000,000,000
Line of Credit Facility    
Debt Instrument [Line Items]    
Maximum Facility Sub-Limit   500,000,000
Line of Credit Facility | Subsequent Event    
Debt Instrument [Line Items]    
Maximum Facility Sub-Limit $ 1,000,000,000  
Line of Credit Facility | Maximum [Member] | Subsequent Event    
Debt Instrument [Line Items]    
Maximum Facility Sub-Limit $ 1,000,000,000  
Letter of Credit    
Debt Instrument [Line Items]    
Maximum Facility Sub-Limit   $ 3,000,000,000
[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 March 31, 2025, the sub-limit for DESC was $500 million. In April 2025, the sub-limit was increased up to $1.0 billion. If DESC has liquidity needs in excess of its sub-limit, the sub-limit may be changed provided that it does not exceed $1.0 billion or such needs may be satisfied through short-term borrowings from Dominion Energy. This credit facility, as amended in April 2025, matures in April 2030, with the potential to be extended by the borrowers to April 2032. The credit facility can be used to support bank borrowings and the issuance of commercial paper, as well as to support up to $3.0 billion (or the sub-limit, whichever is less) of letters of credit.
v3.25.1
Income Taxes - Schedule of Effective Income Tax Rate Reconciliation (Detail)
 3 Months Ended
Mar. 31, 2025
Mar. 31, 2024
Income Tax Disclosure [Abstract]    
U.S. statutory rate 21.00% 21.00%
Increases (reductions) resulting from:    
State taxes, net of federal benefit 10.80% 3.90%
Reversal of excess deferred income taxes (2.40%) (5.30%)
Allowance for equity funds used during construction 0.00% (0.70%)
Remeasurements and settlements of uncertain tax positions (17.50%) 0.00%
Other, net (0.20%) 0.00%
Effective tax rate 11.70% 18.90%
v3.25.1
Income Taxes (Narrative) (Detail)
$ in Millions
Mar. 31, 2025
USD ($)
Income Tax Disclosure [Abstract]  
Income tax net benefit $ 18
Unrecognized tax benefit $ 30
v3.25.1
Derivative Financial Instruments (Narrative) (Detail) - USD ($)
$ in Millions
Mar. 31, 2025
Dec. 31, 2024
Derivative Instruments and Hedging Activities Disclosure [Abstract]    
Additional collateral to its counterparties $ 2 $ 1
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 $ 2 $ 1
v3.25.1
Derivative Financial Instruments (Offsetting Assets and Liabilities) (Detail) - USD ($)
$ in Millions
Mar. 31, 2025
Dec. 31, 2024
Assets    
Derivative [Line Items]    
Assets not offset in the consolidated balance sheet [1] $ 80 $ 83
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 80 83
Over The Counter [Member] | Assets | Interest Rate Contract [Member]    
Derivative [Line Items]    
Assets not offset in the consolidated balance sheet [1] 2 2
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 2
Over The Counter [Member] | Assets | Commodity Contract [Member]    
Derivative [Line Items]    
Assets not offset in the consolidated balance sheet [1] 78 81
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 78 81
Liability    
Derivative [Line Items]    
Gross liabilities presented in the consolidated balance sheet 2 1 [2]
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 2 1
Liability | Over The Counter [Member] | Interest Rate Contract [Member]    
Derivative [Line Items]    
Gross liabilities presented in the consolidated balance sheet 2 1 [2]
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 $ 2 $ 1
[1] Excludes derivative assets of $199 million and $289 million at March 31, 2025 and December 31, 2024, respectively, which are not subject to master netting or similar arrangements.
[2] Excludes derivative liabilities of $5 million at March 31, 2025, which are not subject to master netting or similar arrangements. DESC did not have any derivative liabilities at December 31, 2024 which were not subject to master netting or similar arrangements.
v3.25.1
Derivative Financial Instruments (Offsetting Assets and Liabilities) (Parenthetical) (Details) - USD ($)
Mar. 31, 2025
Dec. 31, 2024
Derivative Instruments and Hedging Activities Disclosure [Abstract]    
Derivative assets not subject to master netting or similar arrangements $ 199,000,000 $ 289,000,000
Derivative liability not subject to master netting or similar arrangements $ 5,000,000 $ 0
v3.25.1
Derivative Financial Instruments (Schedule of Volume of Derivative Activity) (Detail)
MWh in Millions, Bcf in Millions
 3 Months Ended
Mar. 31, 2025
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 41 [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 31 [2]
Interest Rate Swap Noncurrent [Member] | Electricity [Member]  
Derivative [Line Items]  
Fixed price | MWh 22
[1] Maturity is determined based on final settlement period.
[2] Includes options.
v3.25.1
Derivative Financial Instruments (Fair Value of Derivatives) (Detail) - USD ($)
$ in Millions
Mar. 31, 2025
Dec. 31, 2024
Derivative [Line Items]    
Derivative Asset, Current [1] $ 73 $ 63
Derivative Asset, Noncurrent [1] 206 309
Derivative Liability, Current 1 0
Derivative Liability, Noncurrent 6 1
Not Designated as Hedging Instrument [Member]    
Derivative [Line Items]    
Derivative Asset, Current $ 73 $ 63
Derivative Asset, Current, Statement of Financial Position [Extensible Enumeration] Other Assets, Current Other Assets, Current
Derivative Asset, Noncurrent $ 206 $ 309
Derivative Asset, Noncurrent, Statement of Financial Position [Extensible Enumeration] Regulated Entity, Other Assets, Noncurrent Regulated Entity, Other Assets, Noncurrent
Derivative Assets $ 279 $ 372
Derivative Asset, Statement of Financial Position [Extensible Enumeration] Assets Assets
Derivative Liability, Current $ 1 $ 0
Derivative Liability, Current, Statement of Financial Position [Extensible Enumeration] Liabilities, Current Liabilities, Current
Derivative Liability, Noncurrent $ 6 $ 1
Derivative Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration] Liabilities, Noncurrent Liabilities, Noncurrent
Derivative Liability $ 7 $ 1
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 $ 73 $ 63
Derivative Asset, Current, Statement of Financial Position [Extensible Enumeration] Other Assets, Current Other Assets, Current
Derivative Asset, Noncurrent $ 204 $ 307
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 $ 5 $ 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, Current $ 0  
Derivative Asset, Current, Statement of Financial Position [Extensible Enumeration] Other Assets, Current  
Derivative Asset, Noncurrent $ 2 $ 2
Derivative Asset, Noncurrent, Statement of Financial Position [Extensible Enumeration] Regulated Entity, Other Assets, Noncurrent Regulated Entity, Other Assets, Noncurrent
Derivative Liability, Current $ 1  
Derivative Liability, Current, Statement of Financial Position [Extensible Enumeration] Liabilities, Current  
Derivative Liability, Noncurrent $ 1 $ 1
Derivative Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration] Liabilities, Noncurrent Liabilities, Noncurrent
[1] See Note 12 for amounts attributable to affiliates.
v3.25.1
Derivative Financial Instruments (Derivatives in Cash Flow Hedging Relationships) (Detail) - Cash Flow Hedging [Member] - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2025
Mar. 31, 2024
Derivative [Line Items]    
Increase (Decrease) in Derivatives Subject to Regulatory Treatment [1],[2] $ 0 $ 0
Interest Rate Contract [Member]    
Derivative [Line Items]    
Increase (Decrease) in Derivatives Subject to Regulatory Treatment [1],[2] $ 0 $ 0
[1] All derivatives in cash flow hedging relationships have settled and are being amortized over the life of the debt.
[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.
v3.25.1
Derivative Financial Instruments (Derivatives Not Designated as Hedging Instruments) (Detail) - Not Designated as Hedging Instruments [Member] - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2025
Mar. 31, 2024
Derivative [Line Items]    
Amount of Gain (Loss) Recognized in Income on Derivatives [1] $ 2 $ (3)
Commodity Contract [Member] | Purchased Power [Member]    
Derivative [Line Items]    
Amount of Gain (Loss) Recognized in Income on Derivatives [1] 3 (2)
Interest Rate Contract [Member]    
Derivative [Line Items]    
Amount of Gain (Loss) Recognized in Income on Derivatives [1] $ (1) $ (1)
Derivative, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration] Interest Expense, Operating and Nonoperating Interest Expense, Operating and Nonoperating
[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.
v3.25.1
Fair Value Measurements, Including Derivatives (Schedule of Quantitative Information About Level 3 Fair Value Measurements) (Details) - USD ($)
Mar. 31, 2025
Dec. 31, 2024
 [5]
Fair Value, Inputs, Level 3 [Member]    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Total assets, fair value $ 275,000,000  
Total liability, fair value 5,000,000  
Electricity [Member] | Fair Value, Inputs, Level 3 [Member]    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Total assets, fair value 199,000,000  
Total liability, fair value 5,000,000  
Natural gas [Member] | Fair Value, Inputs, Level 3 [Member]    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Total assets, fair value [1] 76,000,000  
Assets [Member] | Electricity [Member] | Fair Value, Inputs, Level 3 [Member] | Minimum [Member]    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Fair value inputs market price (per MWh) [2] 30  
Assets [Member] | Electricity [Member] | Fair Value, Inputs, Level 3 [Member] | Maximum [Member]    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Fair value inputs market price (per MWh) [2] 83  
Assets [Member] | Electricity [Member] | Fair Value, Inputs, Level 3 [Member] | Weighted average [Member]    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Fair value inputs market price (per MWh) [3] 48  
Assets [Member] | Natural gas [Member] | Fair Value, Inputs, Level 3 [Member] | Minimum [Member]    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Fair value inputs market price per decatherm [2] $ 3  
Fair value inputs price volatility [4] 11.00%  
Assets [Member] | Natural gas [Member] | Fair Value, Inputs, Level 3 [Member] | Maximum [Member]    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Fair value inputs market price per decatherm [2] $ 8  
Fair value inputs price volatility [4] 74.00%  
Assets [Member] | Natural gas [Member] | Fair Value, Inputs, Level 3 [Member] | Weighted average [Member]    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Fair value inputs market price per decatherm [3] $ 4  
Fair value inputs price volatility [3] 44.00%  
Liability [Member]    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Total liability, fair value $ 2,000,000 $ 1,000,000
Liability [Member] | Electricity [Member] | Fair Value, Inputs, Level 3 [Member] | Minimum [Member]    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Fair value inputs market price (per MWh) [2] 30  
Liability [Member] | Electricity [Member] | Fair Value, Inputs, Level 3 [Member] | Maximum [Member]    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Fair value inputs market price (per MWh) [2] 81  
Liability [Member] | Electricity [Member] | Fair Value, Inputs, Level 3 [Member] | Weighted average [Member]    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Fair value inputs market price (per MWh) [3] $ 50  
[1] Includes basis.
[2] Represents market prices beyond defined terms for Levels 1 and 2.
[3] Averages weighted by volume.
[4] Represents volatilities unrepresented in published markets.
[5] Excludes derivative liabilities of $5 million at March 31, 2025, which are not subject to master netting or similar arrangements. DESC did not have any derivative liabilities at December 31, 2024 which were not subject to master netting or similar arrangements.
v3.25.1
Fair Value Measurements, Including Derivatives (Schedule of Assets and Liabilities Measured at Fair Value on Recurring Basis) (Details) - Fair value, recurring - USD ($)
$ in Millions
Mar. 31, 2025
Dec. 31, 2024
Assets    
Total assets $ 308 $ 401
Liabilities    
Total liabilities 7 1
Commodity Contract [Member]    
Assets    
Derivatives 277 370
Liabilities    
Total liabilities 5  
Interest Rate Contract [Member]    
Assets    
Derivatives 2 2
Liabilities    
Derivatives 2 1
Cash Equivalents and Other [Member]    
Assets    
Investments 29 29
Level 1    
Assets    
Total assets 29 29
Liabilities    
Total liabilities 0 0
Level 1 | Commodity Contract [Member]    
Assets    
Derivatives 0 0
Liabilities    
Total liabilities 0  
Level 1 | Interest Rate Contract [Member]    
Assets    
Derivatives 0 0
Liabilities    
Derivatives 0 0
Level 1 | Cash Equivalents and Other [Member]    
Assets    
Investments 29 29
Level 2    
Assets    
Total assets 4 2
Liabilities    
Total liabilities 2 1
Level 2 | Commodity Contract [Member]    
Assets    
Derivatives 2 0
Liabilities    
Total liabilities 0  
Level 2 | Interest Rate Contract [Member]    
Assets    
Derivatives 2 2
Liabilities    
Derivatives 2 1
Level 2 | Cash Equivalents and Other [Member]    
Assets    
Investments 0 0
Level 3    
Assets    
Total assets 275 370
Liabilities    
Total liabilities 5 0
Level 3 | Commodity Contract [Member]    
Assets    
Derivatives 275 370
Liabilities    
Total liabilities 5  
Level 3 | Interest Rate Contract [Member]    
Assets    
Derivatives 0 0
Liabilities    
Derivatives 0 0
Level 3 | Cash Equivalents and Other [Member]    
Assets    
Investments $ 0 $ 0
v3.25.1
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
 3 Months Ended
Mar. 31, 2025
Mar. 31, 2024
Regulatory Assets    
Beginning balance $ 370 $ 176
Included in earnings:    
Purchased power 3 (2)
Settlements (14) 2
Purchases 0 7
Ending balance 270 253
Other Regulatory Assets Liabilities    
Included in earnings:    
Included in regulatory assets/liabilities $ (89) $ 70
v3.25.1
Fair Value Measurements, Including Derivatives (Schedule of Assets and Liabilities Measured at Fair Value on Recurring Basis) (Narrative) (Details) - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2025
Mar. 31, 2024
Derivative Instruments and Hedging Activities Disclosure [Abstract]    
Unrealized gains and losses $ 0 $ 0
v3.25.1
Fair Value Measurements, Including Derivatives (Schedule of Carrying Values and Estimated Fair Values of Debt Instruments) (Detail) - USD ($)
$ in Millions
Mar. 31, 2025
Dec. 31, 2024
Carrying Amount    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Long-term debt [1] $ 4,666 $ 4,220
Affiliated long-term debt 230 230
Estimated Fair Value    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Long-term debt [1],[2] 4,632 4,142
Affiliated long-term debt [2] $ 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] 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.
v3.25.1
Employee Benefit Plans (Components of Net Periodic Benefit Cost (Credit) (Detail) - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2025
Mar. 31, 2024
Pension Plan    
Defined Benefit Plan Disclosure [Line Items]    
Service cost $ 2 $ 2
Interest cost 9 8
Expected return on assets (10) (9)
Amortization of actuarial losses 1 2
Net periodic benefit cost (credit) 2 3
Other Postretirement Benefits Plan    
Defined Benefit Plan Disclosure [Line Items]    
Service cost 0 0
Interest cost 2 2
Expected return on assets 0 0
Amortization of actuarial losses (1) (1)
Net periodic benefit cost (credit) $ 1 $ 1
v3.25.1
Employee Benefit Plans (Narrative) (Detail) - Pension Plan - USD ($)
 3 Months Ended
Mar. 31, 2025
Mar. 31, 2024
Defined Benefit Plan Disclosure [Line Items]    
Defined benefit plan, contributions by employer   $ 0
Defined benefit plan, expected contributions in 2025   $ 3,000,000
Maximum    
Defined Benefit Plan Disclosure [Line Items]    
Defined benefit plan, contributions by employer $ 1,000,000  
v3.25.1
Commitments and Contingencies (Narrative) (Detail) - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2025
Mar. 31, 2024
Dec. 31, 2024
Loss Contingencies [Line Items]      
Personal injury or wrongful death charges   $ 6  
Insurance receivable $ 19   $ 10
Reserves related to personal injury or wrongful death cases 16   $ 7
Maximum [Member]      
Loss Contingencies [Line Items]      
Personal injury or wrongful death charges $ 1    
v3.25.1
Commitments and Contingencies (Environmental Matters) (Narrative) (Detail)
gal in Millions, $ in Millions
 1 Months Ended 3 Months Ended
Oct. 31, 2014
MGD
Facility
May 31, 2024
Station
Oct. 31, 2020
Nov. 30, 2019
gal
Sep. 30, 2017
Petition
Apr. 30, 2017
Petition
Aug. 31, 2016
T
Mar. 31, 2025
USD ($)
Indicator
Facility
Product
Mar. 31, 2024
USD ($)
Loss Contingencies [Line Items]                  
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  
Number of facilities inactive subject to final rule | Facility               3  
Increase in regulatory assets | $               $ 98 $ (79)
Unfavorable Regulatory Action | CWA                  
Loss Contingencies [Line Items]                  
Electric generating stations with water withdrawals with heightened entrainment analysis under CWA | MGD 2                
Number of mandatory facility specific factors. | Indicator               5  
Number of optional facility specific factors | Indicator               6  
Unfavorable Regulatory Action | CWA | DESC                  
Loss Contingencies [Line Items]                  
Number of DESC facilities subject to final regulations | Facility 5                
Maximum [Member]                  
Loss Contingencies [Line Items]                  
Estimated environmental remediation activities at manufacturing gas plant sites | $               $ 1  
Environmental Protection Agency And State Regulatory Agencies [Member] | Hydroelectric Facilities                  
Loss Contingencies [Line Items]                  
Number of DESC hydroelectric facilities subject to regulations | Facility 5                
EPA                  
Loss Contingencies [Line Items]                  
Number of petition agreed for reconsideration | Petition         2        
EPA | Unfavorable Regulatory Action                  
Loss Contingencies [Line Items]                  
Electric generating stations with water withdrawals under CWA | MGD 125                
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 | Petition           2      
Loss contingencies facility retirement period   2034              
EPA | Minimum [Member] | Unfavorable Regulatory Action | CWA | Final Rule to Revise Effluent Limitations Guidelines for Steam Electric Power Generating Category                  
Loss Contingencies [Line Items]                  
Loss contingencies individual facilities circumstances period     2021            
EPA | Maximum [Member]                  
Loss Contingencies [Line Items]                  
Number of stations inactive subject to final rule | Station   7              
EPA | Maximum [Member] | Unfavorable Regulatory Action | CWA | Final Rule to Revise Effluent Limitations Guidelines for Steam Electric Power Generating Category                  
Loss Contingencies [Line Items]                  
Loss contingencies individual facilities circumstances period   2029 2028            
Carbon Regulations                  
Loss Contingencies [Line Items]                  
Significant emission rate per year CO2 equivalent | T             75,000    
v3.25.1
Commitments and Contingencies (Surety Bonds) (Narrative) (Details)
Mar. 31, 2025
USD ($)
Surety Bonds  
Loss Contingencies [Line Items]  
Guarantee obligation $ 24,000,000
v3.25.1
Operating Segments - Schedule of Segment Reporting Information, by Segment (Details) - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2025
Mar. 31, 2024
Dec. 31, 2024
Segment Reporting Information [Line Items]      
Operating Revenue [1] $ 986 $ 775  
Fuel used in electric generation [2] 204 145  
Purchased power [1],[2] 22 10  
Gas purchased for resale [2] 126 79  
Other operations and maintenance [2] 174 163  
Depreciation and amortization [2] 140 136  
Other taxes [1],[2] 82 78  
Total operating expenses 748 611  
Other income (expense), net [3] 3 1  
Interest charges, net of AFUDC [2] 71 67  
Income tax expense [2] 20 18  
Comprehensive Income Attributable to Noncontrolling Interest [3] 8 6  
Comprehensive Income (Loss) Available (Attributable) to Common Shareholder 142 74  
Capital expenditures 297 268  
Total assets 17,118   $ 17,041
Dominion Energy South Carolina, Inc. [Member]      
Segment Reporting Information [Line Items]      
Operating Revenue 986 775  
Fuel used in electric generation [2] 204 145  
Purchased power [2] 22 10  
Gas purchased for resale [2] 126 79  
Other operations and maintenance [2] 174 163  
Depreciation and amortization [2] 140 136  
Other taxes [2] 82 78  
Total operating expenses 748 611  
Other income (expense), net [3] 3 1  
Interest charges, net of AFUDC [2] 71 67  
Income tax expense [2] 18 17  
Comprehensive Income Attributable to Noncontrolling Interest [3] 8 6  
Comprehensive Income (Loss) Available (Attributable) to Common Shareholder 144 75  
Capital expenditures 297 268  
Total assets 17,100    
Corporate and Other      
Segment Reporting Information [Line Items]      
Operating Revenue 0 0  
Fuel used in electric generation [2] 0 0  
Purchased power [2] 0 0  
Gas purchased for resale [2] 0 0  
Other operations and maintenance [2] 0 0  
Depreciation and amortization [2] 0 0  
Other taxes [2] 0 0  
Total operating expenses 0 0  
Other income (expense), net [3] 0 0  
Interest charges, net of AFUDC [2] 0 0  
Income tax expense [2] 2 1  
Comprehensive Income Attributable to Noncontrolling Interest [3] 0 0  
Comprehensive Income (Loss) Available (Attributable) to Common Shareholder (2) (1)  
Capital expenditures 0 $ 0  
Total assets $ 0    
[1] See Note 12 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.
v3.25.1
Affiliated and Related Party Transactions (Schedule of Affiliated Transactions - Income Statement) (Detail) - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2025
Mar. 31, 2024
Related Party Transaction [Line Items]    
Operating Revenues - Electric from sales to affiliate $ 1 $ 1
Operating Expenses - Other taxes from affiliate 3 3
Related Party | DES    
Related Party Transaction [Line Items]    
Direct and allocated costs [1] 62 53
Solar Affiliates [Member]    
Related Party Transaction [Line Items]    
Purchases from affiliate $ 3 $ 1
[1] Includes capitalized expenditures of $19 million and $12 million for the three months ended March 31, 2025 and 2024, respectively.
v3.25.1
Affiliated and Related Party Transactions (Schedule of Affiliated Transactions - Income Statement) (Parenthetical) (Detail) - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2025
Mar. 31, 2024
DES    
Related Party Transaction [Line Items]    
Capitalized expenditures $ 19 $ 12
v3.25.1
Affiliated and Related Party Transactions (Schedule of Affiliated Transactions - Balance Sheet) (Detail) - USD ($)
$ in Millions
Mar. 31, 2025
Dec. 31, 2024
Related Party Transaction [Line Items]    
Affiliated and related party payables and other $ 159 $ 201
Derivative assets with affiliates [1] 33 48
DES | Related Party    
Related Party Transaction [Line Items]    
Affiliated and related party payables and other 19 19
SCANA Corporation | Related Party    
Related Party Transaction [Line Items]    
Affiliated and related party payables and other $ 7 $ 7
[1] Includes amounts recorded in current derivative assets of $6 million and $4 million as of March 31, 2025 and December 31, 2024, respectively, and amounts recorded in noncurrent derivative assets of $27 million and $44 million as of March 31, 2025 and December 31, 2024, respectively.
v3.25.1
Affiliated and Related Party Transactions (Schedule of Affiliated Transactions - Balance Sheet) (Parenthetical) (Detail) - USD ($)
$ in Millions
Mar. 31, 2025
Dec. 31, 2024
Related Party Transaction [Line Items]    
Derivative assets with affiliates [1] $ 33 $ 48
Current Derivative Assets [Member]    
Related Party Transaction [Line Items]    
Derivative assets with affiliates 6 4
Noncurrent Derivative Assets [Member]    
Related Party Transaction [Line Items]    
Derivative assets with affiliates $ 27 $ 44
[1] Includes amounts recorded in current derivative assets of $6 million and $4 million as of March 31, 2025 and December 31, 2024, respectively, and amounts recorded in noncurrent derivative assets of $27 million and $44 million as of March 31, 2025 and December 31, 2024, respectively.
v3.25.1
Other Income (Expense), Net (Components of Other Income (Expense), Net) (Detail) - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2025
Mar. 31, 2024
Income Statement [Abstract]    
Other income $ 5 $ 2
Gains on sales of assets 0 1
Other expense (2) (5)
Allowance for equity funds used during construction 0 3
Other income (expense), net [1] $ 3 $ 1
[1] Items designated are other segment items for each reportable segment.