10-Q

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, DC 20549

FORM 10-Q

☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the quarterly period ended September 30, 2023

☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the transition period from _____ to _____

		I.R.S. Employer
Commission File Number	Exact name of registrant as specified in its charter	Identification Number
001-3375	DOMINION ENERGY SOUTH CAROLINA, INC.	57-0248695
	south carolina
	(State or other jurisdiction of incorporation or organization)
	400 OTARRE PARKWAY
	CAYCE, South Carolina	29033
	(Address of principal executive offices)	(Zip Code)
	(804) 819-2284
	(Registrants’ telephone number)

Securities registered pursuant to Section 12(b) of the Act:

None

Indicate by check mark whether the registrant: (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days. Yes ☒ No ☐

Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit such files). Yes ☒ No ☐

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “non-accelerated filer,” “smaller reporting company” and "emerging growth company" in Rule 12b-2 of the Exchange Act.

Large accelerated filer	☐	Accelerated filer	☐	Emerging growth company	☐
Non-accelerated filer	☒	Smaller reporting company	☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act). Yes ☐ No ☒

Indicate the number of shares outstanding of each of the issuer’s classes of common stock, as of the latest practicable date. At November 2, 2023, Dominion Energy South Carolina, Inc. had outstanding 40,296,147 shares of common stock, all of which were held by SCANA Corporation, a wholly-owned subsidiary of Dominion Energy, Inc.

Dominion Energy South Carolina, Inc. meets the conditions set forth in General Instruction H(1)(a) and (b) of Form 10-Q and is filing this Form 10-Q under the reduced disclosure format.

TABLE OF CONTENTS

		Page
	Glossary of Terms	3
PART I. FINANCIAL INFORMATION
Item 1.	Financial Statements	5
Item 2.	Management's Discussion and Analysis of Financial Condition and Results of Operations	26
Item 4.	Controls and Procedures	30
PART II. OTHER INFORMATION
Item 1.	Legal Proceedings	31
Item 1A.	Risk Factors	31
Item 5.	Other Information	31
Item 6.	Exhibits	32

2

GLOSSARY OF TERMS

The following abbreviations or acronyms used in this Form 10-Q are defined below:

Abbreviation or Acronym	Definition
2017 Tax Reform Act	An Act to Provide for Reconciliation Pursuant to Titles II and V of the Concurrent Resolution on the Budget for Fiscal Year 2018 (previously known as The Tax Cuts and Jobs Act) enacted on December 22, 2017
ACE Rule	Affordable Clean Energy Rule
AFUDC	Allowance for funds used during construction
AOCI	Accumulated other comprehensive income (loss)
ARO	Asset retirement obligation
BACT	Best available control technology
CAA	Clean Air Act
CCR	Coal combustion residual
CEO	Chief Executive Officer
CERCLA	Comprehensive Environmental Response, Compensation and Liability Act of 1980, also known as Superfund
CFO	Chief Financial Officer
CO2	Carbon dioxide
CUA	Capacity Use Area
CWA	Clean Water Act
DES	Dominion Energy Services, Inc.
DESC	The legal entity, Dominion Energy South Carolina, Inc., one or more of its consolidated entities or operating segment, or the entirety of Dominion Energy South Carolina, Inc. and its consolidated entities
Dominion Energy	The legal entity, Dominion Energy, Inc., one or more of its consolidated subsidiaries (other than DESC) or operating segments, or the entirety of Dominion Energy, Inc. and its consolidated subsidiaries
Dominion Energy South Carolina	Dominion Energy South Carolina operating segment
DSM	Demand-side management
ELG Rule	Effluent limitations guidelines for the steam electric power generating category
EPA	U.S. Environmental Protection Agency
FERC	Federal Energy Regulatory Commission
Fuel Company	South Carolina Fuel Company, Inc.
GAAP	U.S. generally accepted accounting principles
GENCO	South Carolina Generating Company, Inc.
GHG	Greenhouse gas
kV	Kilovolt
MD&A	Management's Discussion and Analysis of Financial Condition and Results of Operations
MGD	Million gallons per day
MWh	Megawatt hour
NND Project	V. C. Summer Units 2 and 3 nuclear development project under which DESC and Santee Cooper undertook to construct two Westinghouse AP1000 Advanced Passive Safety nuclear units in Jenkinsville, South Carolina
NOx	Nitrogen oxide
Order 1000	Order issued by FERC adopting requirements for electric transmission planning, cost allocation and development
PSD	Prevention of significant deterioration
Questar Gas	Questar Gas Company, a wholly-owned subsidiary of Dominion Energy
ROE	Return on equity
Santee Cooper	South Carolina Public Service Authority

3

Abbreviation or Acronym	Definition
SCANA	The legal entity, SCANA Corporation, one or more of its consolidated subsidiaries (other than DESC) or the entirety of SCANA Corporation and its consolidated subsidiaries
SCANA Combination	Dominion Energy's acquisition of SCANA completed on January 1, 2019 pursuant to the terms of the SCANA Merger Agreement
SCANA Merger Agreement	Agreement and plan of merger entered on January 2, 2018 between Dominion Energy and SCANA
SCANA Merger Approval Order	Final order issued by the South Carolina Commission on December 21, 2018 setting forth its approval of the SCANA Combination
SCDHEC	South Carolina Department of Health and Environmental Control
SCDOR	South Carolina Department of Revenue
SEC	U.S. Securities and Exchange Commission
SO2	Sulfur dioxide
South Carolina Commission	Public Service Commission of South Carolina
Summer	V. C. Summer nuclear power station
Toshiba	Toshiba Corporation, parent company of Westinghouse
Toshiba Settlement	Settlement Agreement dated as of July 27, 2017, by and among Toshiba, DESC and Santee Cooper
VIE	Variable interest entity
Virginia Power	The legal entity, Virginia Electric and Power Company, a wholly-owned subsidiary of Dominion Energy, one or more of its consolidated subsidiaries or operating segment, or the entirety of Virginia Electric and Power Company and its consolidated subsidiaries
Westinghouse	Westinghouse Electric Company LLC

4

PART I. FINANCIAL INFORMATION

ITEM 1. FINANCIAL STATEMENTS

Dominion Energy South Carolina, Inc.

Consolidated Balance Sheets

(Unaudited)

(millions)	September 30, 2023			December 31, 2022
ASSETS
Utility plant in service	$	15,209		$	14,688
Accumulated depreciation and amortization		(5,497	)		(5,335	)
Construction work in progress		616			541
Nuclear fuel, net of accumulated amortization		198			204
Utility plant, net ($726 and $719 related to VIEs)		10,526			10,098
Nonutility Property and Investments:
Nonutility property, net of accumulated depreciation		27			20
Assets held in trust, nuclear decommissioning		230			223
Nonutility property and investments, net		257			243
Current Assets:
Cash and cash equivalents		8			11
Receivables:
Customer, net of allowance for uncollectible accounts of $7 and $5		405			420
Affiliated and related party		—			2
Other		89			141
Inventories (at average cost):
Fuel		90			98
Gas stored		31			38
Materials and supplies		233			218
Prepayments		102			76
Regulatory assets		563			743
Other current assets(1)		29			49
Current assets held for sale		—			8
Total current assets ($84 and $92 related to VIEs)		1,550			1,804
Deferred Debits and Other Assets:
Regulatory assets		3,182			3,289
Other(1)		261			315
Total deferred debits and other assets ($26 and $23 related to VIEs)		3,443			3,604
Total assets	$	15,776		$	15,749

(1) See Note 12 for amounts attributable to affiliates.

See Notes to Consolidated Financial Statements.

5

Dominion Energy South Carolina, Inc.

Consolidated Balance Sheets—(Continued)

(Unaudited)

(millions)	September 30, 2023			December 31, 2022
CAPITALIZATION AND LIABILITIES
Common Stock - no par value, 40.3 million shares outstanding	$	4,088		$	4,088
Retained earnings		577			418
Accumulated other comprehensive loss		(2	)		(2	)
Total common equity		4,663			4,504
Noncontrolling interest		177			162
Total equity		4,840			4,666
Long-term debt, net		3,726			3,725
Affiliated long-term debt		—			230
Finance leases		4			6
Total long-term debt		3,730			3,961
Total capitalization		8,570			8,627
Current Liabilities:
Short-term borrowings		287			249
Securities due within one year		3			4
Accounts payable		133			297
Affiliated and related party payables		1,323			871
Customer deposits and customer prepayments		73			79
Taxes accrued		187			236
Interest accrued		66			75
Regulatory liabilities		212			251
Reserves for litigation and regulatory proceedings		3			94
Other		135			115
Total current liabilities		2,422			2,271
Deferred Credits and Other Liabilities:
Deferred income taxes and investment tax credits		1,249			1,230
Asset retirement obligations		689			628
Pension and other postretirement benefits		114			114
Regulatory liabilities		2,629			2,785
Affiliated liabilities		24			19
Other		79			75
Total deferred credits and other liabilities		4,784			4,851
Commitments and Contingencies (see Note 10)
Total capitalization and liabilities	$	15,776		$	15,749

See Notes to Consolidated Financial Statements.

6

Dominion Energy South Carolina, Inc.

Consolidated Statements of Comprehensive Income

(Unaudited)

	Three Months Ended September 30,					Nine Months Ended September 30,
(millions)	2023			2022		2023		2022
Operating Revenue(1)	$	848		$	1,083	$	2,311	$	2,841
Operating Expenses:
Fuel used in electric generation		169			342		454		770
Purchased power(1)		24			28		60		86
Gas purchased for resale		47			102		174		296
Other operations and maintenance		119			117		334		343
Other operations and maintenance - affiliated suppliers		38			40		121		122
Impairment of assets and other charges		—			2		—		6
Depreciation and amortization		135			127		395		378
Other taxes(1)		69			72		221		216
Total operating expenses		601			830		1,759		2,217
Operating income		247			253		552		624
Other income (expense), net		(2	)		22		26		46
Interest charges, net of AFUDC of $6, $1, $15 and $3(1)		64			57		186		162
Income before income tax expense		181			218		392		508
Income tax expense		35			45		68		102
Net Income and Other Comprehensive Income		146			173		324		406
Comprehensive Income Attributable to Noncontrolling    Interest		5			5		15		16
Comprehensive Income Available to Common Shareholder	$	141		$	168	$	309	$	390

(1) See Note 12 for amounts attributable to affiliates.

See Notes to Consolidated Financial Statements.

7

Dominion Energy South Carolina, Inc.

Consolidated Statements of Cash Flows

(Unaudited)

	Nine Months Ended September 30,
(millions)	2023			2022
Operating Activities
Net income	$	324		$	406
Adjustments to reconcile net income to net cash provided by operating activities:
Impairment of assets and other charges		—			4
Deferred income taxes, net		19			201
Depreciation and amortization		395			378
Amortization of nuclear fuel		23			29
Gains on sale of assets		(32	)		(37	)
Other adjustments		8			3
Changes in certain assets and liabilities:
Receivables		29			(23	)
Receivables - affiliated and related party		2			14
Inventories		—			(59	)
Prepayments		(26	)		(14	)
Regulatory assets		197			(356	)
Regulatory liabilities		(243	)		(35	)
Accounts payable		(95	)		(5	)
Accounts payable - affiliated and related party		(36	)		56
Taxes accrued		(49	)		(37	)
Interest accrued		(9	)		(5	)
Pension and other postretirement benefits		—			(4	)
Other assets and liabilities		75			(192	)
Net cash provided by operating activities		582			324
Investing Activities
Property additions and construction expenditures		(706	)		(514	)
Proceeds from investments and sales of assets		(23	)		(7	)
Purchase of investments		(4	)		(1	)
Other		4			12
Net cash used in investing activities		(729	)		(510	)
Financing Activities
Dividend to parent		(150	)		(348	)
Short-term borrowings, net		38			250
Short-term borrowings - affiliated, net		258			239
Other		(2	)		(3	)
Net cash provided by financing activities		144			138
Net decrease in cash, restricted cash and equivalents		(3	)		(48	)
Cash, restricted cash and equivalents at beginning of period(1)		11			54
Cash, restricted cash and equivalents at end of period(1)	$	8		$	6
Supplemental Cash Flow Information
Significant noncash investing and financing activities:(2)
Accrued construction expenditures	$	65		$	106
Operating leases		2			6

(1)Includes $24 million of restricted cash at December 31, 2021, recorded within other current assets on the Consolidated Balance Sheets. At September 30, 2023, September 30, 2022 and December 31, 2022 there were no restricted cash and equivalent balances.

(2)See Note 10 for noncash investing activities related to the transfer of property associated with the settlement of litigation.

See Notes to Consolidated Financial Statements.

8

Dominion Energy South Carolina, Inc.

Consolidated Statements of Changes in Common Equity

(Unaudited)

Quarter-To-Date

	Common Stock
(millions)	Shares		Amount		Retained Earnings			AOCI			Noncontrolling Interest			Total Equity
June 30, 2022		40	$	4,088	$	357		$	(1	)	$	168		$	4,612
Total comprehensive income available to    common shareholder						168						5			173
Dividend to parent						(115	)					(15	)		(130	)
September 30, 2022		40	$	4,088	$	410		$	(1	)	$	158		$	4,655
June 30, 2023		40	$	4,088	$	486		$	(2	)	$	172		$	4,744
Total comprehensive income available to    common shareholder						141						5			146
Dividend to parent						(50	)								(50	)
September 30, 2023		40	$	4,088	$	577		$	(2	)	$	177		$	4,840

Year-To-Date

	Common Stock
(millions)	Shares		Amount		Retained Earnings			AOCI			Noncontrolling Interest			Total Equity
December 31, 2021		40	$	4,016	$	335		$	(1	)	$	175		$	4,525
Total comprehensive income available to    common shareholder						390						16			406
Capital contribution from parent				72											72
Dividend to parent						(315	)					(33	)		(348	)
September 30, 2022		40	$	4,088	$	410		$	(1	)	$	158		$	4,655
December 31, 2022		40	$	4,088	$	418		$	(2	)	$	162		$	4,666
Total comprehensive income available to    common shareholder						309						15			324
Dividend to parent						(150	)								(150	)
September 30, 2023		40	$	4,088	$	577		$	(2	)	$	177		$	4,840

See Notes to Consolidated Financial Statements.

9

Dominion Energy South Carolina, Inc.

Notes to Consolidated Financial Statements

(Unaudited)

The following notes should be read in conjunction with the Notes to Consolidated Financial Statements appearing in DESC's Annual Report on Form 10-K for the year ended December 31, 2022.

These are interim financial statements and, due to the seasonality of DESC's business and matters that may occur during the rest of the year, the amounts reported in the Consolidated Statements of Comprehensive Income are not necessarily indicative of amounts expected for the full year. In the opinion of management, the information furnished herein reflects all adjustments which are necessary for a fair statement of the results for the interim periods reported, and such adjustments are of a normal recurring nature unless otherwise noted. In addition, the preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amount of revenues and expenses during the reporting period. Actual results could differ from those estimates.

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

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

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, 2022 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, 2022, except as follows.

Asset Retirement Obligations

In the second quarter of 2023, DESC revised its estimated cash flow projections for AROs associated with certain previously retired coal-fired generating units. As a result, DESC recorded a $43 million increase to AROs with a corresponding increase to regulatory assets.

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

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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, 2022.

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 2023, 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 2023, along with a requested decrease to DESC's variable environmental and avoided capacity cost component. The net effect of the proposal is an annual increase of $176 million. In March 2023, DESC, the South Carolina Office of Regulatory Staff and another party of record filed a stipulation with the South Carolina Commission for approval to reduce the base fuel cost component reflecting a subsequent decrease in current fuel prices, resulting in a net annual increase of $121 million. In April 2023, the South Carolina Commission voted to approve the stipulation, with rates effective May 2023.

Electric Transmission Project

In March 2023, DESC filed an application with the South Carolina Commission requesting approval to construct and operate 19 miles of 230 kV transmission lines, a substation and associated facilities in Jasper County, South Carolina estimated to cost approximately $55 million. In July 2023, the South Carolina Commission voted to approve the request and issued its order in September 2023.

Electric – Other

DESC has approval for a DSM rider through which it recovers expenditures related to its DSM programs. In January 2023, 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 2023. In April 2023, the South Carolina Commission approved the request, effective with the first billing cycle of May 2023.

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 2023, DESC requested that the South Carolina Commission approve an adjustment to this rider to increase annual revenue by $24 million. In April 2023, the South Carolina Commission approved the request.

Natural Gas Base Rate Case

In March 2023, DESC filed its natural gas base rate case and schedules with the South Carolina Commission. DESC proposed a rate increase of $19 million effective October 2023. The base rate increase was proposed to recover significant investment in distribution infrastructure for the benefit of customers. The proposed rates would provide for an ROE of 10.38% compared to the currently authorized ROE of 10.25%. In addition, DESC elected to continue applicability of the Natural Gas Rate Stabilization Act, which allows for the adjustment of natural gas base rates annually, to its future rates and charges. In September 2023, DESC, the South Carolina Office of Regulatory Staff and other parties of record filed a stipulation agreement with the South Carolina Commission for approval. The stipulation agreement provides for a rate increase of $9 million commencing with bills rendered in October 2023, and an authorized ROE of 9.49%. Pursuant to the stipulation agreement, DESC would not file a natural gas base rate case prior to April 1, 2026, such that new rates would not be effective prior to October 1, 2026, absent unforeseen extraordinary economic or financial conditions that may include changes in corporate tax rates. In September 2023, the South Carolina Commission approved the stipulation agreement and issued its final order in October 2023.

11

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.

	September 30,		December 31,
(millions)	2023		2022
Regulatory assets:
NND Project costs(1)	$	138	$	138
AROs(2)		44		8
Deferred employee benefit plan costs(3)		11		4
Other unrecovered plant(4)		18		17
DSM programs(5)		20		21
Cost of fuel and purchased gas under-collections(6)		275		508
Other		57		47
Regulatory assets - current		563		743
NND Project costs(1)		1,984		2,088
AROs(2)		399		381
Deferred employee benefit plan costs(3)		145		161
Interest rate hedges(7)		168		169
Other unrecovered plant(4)		55		58
DSM programs(5)		43		41
Environmental remediation costs(8)		39		37
Deferred storm damage costs(9)		40		43
Deferred transmission operating costs(10)		74		75
Derivatives(11)		101		105
Other(12)		134		131
Regulatory assets - noncurrent		3,182		3,289
Total regulatory assets	$	3,745	$	4,032
Regulatory liabilities:
Monetization of guaranty settlement(13)	$	67	$	67
Income taxes refundable through future rates(14)		36		34
Reserve for refunds to electric utility customers(15)		87		100
Derivatives(11)		21		43
Other		1		7
Regulatory liabilities - current		212		251
Monetization of guaranty settlement(13)		652		702
Income taxes refundable through future rates(14)		847		871
Asset removal costs(16)		645		596
Reserve for refunds to electric utility customers(15)		261		325
Derivatives(11)		218		276
Other		6		15
Regulatory liabilities - noncurrent		2,629		2,785
Total regulatory liabilities	$	2,841	$	3,036

(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.

(3)Employee benefit plan costs have historically been recovered as they have been recorded under GAAP. Deferred employee benefit plan costs represent amounts of pension and other postretirement benefit costs which were accrued as liabilities and treated as regulatory assets pursuant to FERC guidance, and costs deferred pursuant to specific South Carolina Commission regulatory orders. DESC expects to recover deferred pension costs through utility rates over periods through 2044. DESC expects to recover other deferred benefit costs through utility rates, primarily over average service periods of participating employees up to 11 years.

(4)Represents the carrying value of coal-fired generating units, including related materials and supplies inventory, retired from service prior to being fully depreciated. DESC is amortizing these amounts through cost of service rates following depreciation amounts that were designed to recover the retired units cost over their previous estimated remaining useful lives, which has been estimated to be through 2025. Based on

12

current projections of remaining decommissioning costs, projected recovery is expected to extend through 2033. 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 over five years related to the transition or conversion from coal to gas fired generation at certain facilities.

(5)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 the changes in fair value and payments made or received upon settlement of certain interest rate derivatives designated as cash flow hedges. The amounts recorded are 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 29 years. See Note 10 for additional information.

(9)Represents storm restoration costs for which DESC expects to receive future recovery through customer rates over approximately 10 years pursuant to the settlement agreement approved in DESC’s retail electric base rate case. 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 recovery from customers through future rates over approximately 42 years pursuant to the settlement agreement approved in DESC’s retail electric base rate case. Unamortized amounts are included in rate base and earning a current return. See Note 12 to the Consolidated Financial Statements in DESC’s Annual Report on Form 10-K for the year ended December 31, 2022.

(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 2047.

(13)Represents proceeds related to the monetization of the Toshiba Settlement. In accordance with the SCANA Merger Approval Order, this balance, net of amounts that may be required to satisfy liens, will be refunded to electric customers over a 20-year period ending in 2039.

(14)Includes (i) excess deferred income taxes arising from the remeasurement of deferred income taxes in connection with the enactment of the 2017 Tax Reform Act (certain of which are protected under normalization rules and will be amortized over the remaining lives of related property, and certain of which will be amortized to the benefit of customers over prescribed periods as instructed by regulators) and (ii) deferred income taxes arising from investment tax credits, offset by (iii) deferred income taxes that arise from utility operations that have not been included in customer rates (a portion of which relate to depreciation and are expected to be recovered over the remaining lives of the related property which may range up to 85 years). See Note 7 to the Consolidated Financial Statements in DESC’s Annual Report on Form 10-K for the year ended December 31, 2022 for additional information.

(15)Reflects amounts previously collected from retail electric customers of DESC for the NND Project to be credited to customers over an estimated 11-year period effective February 2019 in connection with the SCANA Merger Approval Order.

(16)Represents estimated net collections through depreciation rates of amounts to be expended for the removal of assets in the future.

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

3. REVENUE RECOGNITION

DESC has disaggregated operating revenues by customer class as follows:

	Quarter-to-Date September 30, 2023				Quarter-to-Date September 30, 2022				Year-to-Date September 30, 2023				Year-to-Date September 30, 2022
(millions)	Electric		Gas		Electric		Gas		Electric		Gas		Electric		Gas
Customer class:
Residential	$	382	$	34	$	433	$	39	$	910	$	186	$	1,065	$	193
Commercial		238		23		294		41		633		90		740		124
Industrial		94		19		153		54		282		56		396		128
Other		41		8		56		4		114		18		156		16
Revenues from contracts with customers		755		84		936		138		1,939		350		2,357		461
Other revenues		9		—		8		1		21		1		22		1
Total Operating Revenues	$	764	$	84	$	944	$	139	$	1,960	$	351	$	2,379	$	462

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 $7 million and $12 million at September 30, 2023 and

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December 31, 2022, respectively. During the nine months ended September 30, 2023 and 2022, DESC recognized revenue of $9 million and $6 million, respectively, from the beginning contract liability balances as DESC fulfilled its obligations to provide service to its customers. Contract liabilities are recorded in customer deposits and customer prepayments in the Consolidated Balance Sheets.

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

	Regulatory Assets
(millions)	September 30, 2023		December 31, 2022
Beginning balance	$	9	$	11
Amortization		—		(2	)
Ending balance	$	9	$	9

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.

In May 2022, Dominion Energy issued $72 million of shares of Dominion Energy common stock to partially satisfy DESC’s remaining obligation under a settlement agreement with the SCDOR discussed in Note 10. In connection with this transaction, DESC recorded an equity contribution from Dominion Energy in the second quarter of 2022.

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, 2022.

5. LONG-TERM AND SHORT-TERM DEBT

DESC’s short-term financing is supported through its access as co-borrower to Dominion Energy’s $6.0 billion joint revolving credit facility, which can be used for working capital, as support for the combined commercial paper programs of DESC, Dominion Energy, Virginia Power and Questar Gas, 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, 2022.

At September 30, 2023, 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	$	287	$	—

(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, Virginia Power and Questar Gas. 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 September 30, 2023, the sub-limit for DESC was $500 million. If DESC has liquidity needs in excess of its sub-limit, the sub-limit may be changed or such needs may be satisfied through short-term intercompany borrowings from Dominion Energy. This credit facility matures in June 2026, with the potential to be extended by the borrowers to June 2028. The credit facility can be used to support bank borrowings and the issuance of commercial paper, as well as to support up to $1.0 billion (or the sub-limit, whichever is less) of letters of credit.

In March 2023, FERC granted DESC authority through March 2025 to issue short-term indebtedness (pursuant to Section 204 of the Federal Power Act) in amounts not to exceed $2.2 billion outstanding with maturity dates of one year or less. In addition, in March 2023, FERC granted GENCO authority through March 2025 to issue short-term indebtedness not to exceed $200 million outstanding with maturity dates of one year or less.

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 September 30, 2023 and December 31, 2022, DESC, GENCO and Fuel Company collectively had borrowings outstanding under these agreements totaling $1.0 billion and $769 million, respectively, which are recorded in affiliated and related party payables in DESC’s Consolidated Balance Sheets. Interest charges associated with these agreements were $16 million and $4 million for the three months ended September 30, 2023 and 2022, respectively, and $44 million and $9 million for the nine months ended September 30, 2023 and 2022, respectively.

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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 2024.

In October 2023, DESC issued $500 million of 6.25% first mortgage bonds that mature in 2053 with proceeds used for general corporate purposes and to repay short-term borrowings, including borrowings under DESC's intercompany credit facility with Dominion Energy.

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:

Nine Months Ended September 30,	2023			2022
U.S. statutory rate		21.0	%		21.0	%
Increases (reductions) resulting from:
State taxes, net of federal benefit		4.1			4.0
Reversal of excess deferred income taxes		(4.8	)		(4.5	)
Allowance for equity funds used during construction		—			(0.2	)
Settlements of uncertain tax positions		(2.7	)		—
Other, net		(0.2	)		(0.2	)
Effective tax rate		17.4	%		20.1	%

As of September 30, 2023, DESC’s effective tax rate reflects an income tax benefit of $11 million from the effective settlement of a position that management believed was reasonably possible to occur. Otherwise, there have been no material changes in DESC’s unrecognized tax benefits. See Note 7 to the Consolidated Financial Statements in DESC's Annual Report on Form 10-K for the year ended December 31, 2022 for a discussion of these unrecognized tax benefits.

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, 2022. 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. 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 September 30, 2023 and December 31, 2022, DESC would have been required to post $— 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, non-derivative contracts and derivatives elected under the normal purchases and normal sales exception, per contractual terms. DESC had posted $1 million of collateral at both September 30, 2023 and December 31, 2022 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 September 30, 2023 and December 31, 2022 was $1 million and $2 million, respectively, which does not include the impact of any offsetting asset positions.

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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. DESC’s commodity derivative assets are not subject to a master netting agreement or similar arrangement.

	September 30, 2023								December 31, 2022
	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		Financial Instruments		Cash Collateral Received		Net Amounts		Gross Assets Presented in the Consolidated Balance Sheet		Financial Instruments		Cash Collateral Received		Net Amounts
Interest rate contracts:
Over-the-counter	$	2	$	—	$	—	$	2	$	1	$	—	$	—	$	1
Total derivatives	$	2	$	—	$	—	$	2	$	1	$	—	$	—	$	1

	September 30, 2023								December 31, 2022
	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		Financial Instruments		Cash Collateral Paid		Net Amounts		Gross Liabilities Presented in the Consolidated Balance Sheet		Financial Instruments		Cash Collateral Paid		Net Amounts
Interest rate contracts:
Over-the-counter	$	1	$	—	$	1	$	—	$	2	$	—	$	1	$	1
Total derivatives	$	1	$	—	$	1	$	—	$	2	$	—	$	1	$	1

Volumes

The following table presents the volume of derivative activity at September 30, 2023. These volumes are based on open derivative positions and represent the combined absolute value of their long and short positions.

	Current		Noncurrent
Electricity (MWh in millions):
Fixed price		2		22
Interest rate(1)(in millions)	$	—	$	71

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

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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:

(millions)	Fair Value - Derivatives under Hedge Accounting		Fair Value - Derivatives not under Hedge Accounting		Total Fair Value
At September 30, 2023
ASSETS
Current Assets
Commodity	$	—	$	18	$	18
Total current derivative assets(1)		—		18		18
Noncurrent Assets
Commodity		—		153		153
Interest rate		—		2		2
Total noncurrent derivative assets(2)		—		155		155
Total derivative assets	$	—	$	173	$	173
LIABILITIES
Noncurrent Liabilities
Interest rate		—		1		1
Total noncurrent derivative liabilities(3)		—		1		1
Total derivative liabilities	$	—	$	1	$	1
At December 31, 2022
ASSETS
Current Assets
Commodity	$	—	$	41	$	41
Total current derivative assets(1)		—		41		41
Noncurrent Assets
Commodity		—		210		210
Interest rate		—		1		1
Total noncurrent derivative assets(2)		—		211		211
Total derivative assets	$	—	$	252	$	252
LIABILITIES
Noncurrent Liabilities
Interest rate		2		—		2
Total noncurrent derivative liabilities(3)		2		—		2
Total derivative liabilities	$	2	$	—	$	2

(1)Current derivative assets are presented in other current assets in DESC’s Consolidated Balance Sheets.

(2)Noncurrent derivative assets are presented in other deferred debits and other assets in DESC’s Consolidated Balance Sheets.

(3)Noncurrent derivative liabilities are presented in other deferred credits and other liabilities in DESC’s Consolidated Balance Sheets.

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)
Three Months Ended September 30,	2023		2022
Derivative type and location of gains (losses):
Interest rate	$	—	$	2
Total	$	—	$	2
Nine Months Ended September 30,
Derivative type and location of gains (losses):
Interest rate	$	—	$	10
Total	$	—	$	10

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

Derivatives Not Designated as Hedging Instruments

(millions)	Amount of Gain (Loss) Recognized in Income on Derivatives(1)
Three Months Ended September 30,	2023			2022
Derivative type and location of gains (losses):
Commodity:
Purchased power	$	4		$	48
Interest rate:
Interest charges		—			(1	)
Total	$	4		$	47
Nine Months Ended September 30,
Derivative type and location of gains (losses):
Commodity:
Purchased power	$	4		$	66
Interest rate:
Interest charges		(1	)		(2	)
Total	$	3		$	64

(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.

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, 2022. 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 September 30, 2023. The range and weighted average are presented in dollars for market price inputs.

	Fair Value (millions)		Valuation Techniques	Unobservable Input		Range	Weighted Average(1)
Assets
Physical forwards:
Electricity	$	171	Discounted cash flow	Market price (per MWh)	(2)	25-92	48
Total assets	$	171

(1)Averages weighted by volume.

(2)Represents market prices beyond defined terms for Levels 1 and 2.

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)

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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 September 30, 2023
Assets
Commodity	$	—	$	—	$	171	$	171
Interest rate		—		2		—		2
Total assets	$	—	$	2	$	171	$	173
Liabilities
Interest rate	$	—	$	1	$	—	$	1
Total liabilities	$	—	$	1	$	—	$	1
At December 31, 2022
Assets
Commodity	$	—	$	—	$	251	$	251
Interest rate		—		1		—		1
Total assets	$	—	$	1	$	251	$	252
Liabilities
Interest rate	$	—	$	2	$	—	$	2
Total liabilities	$	—	$	2	$	—	$	2

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						Nine Months Ended
	September 30,						September 30,
	2023			2022			2023			2022
(millions)
Beginning balance	$	167		$	295		$	251		$	148
Total realized and unrealized gains (losses):
Included in earnings:
Purchased power		5			48			5			66
Included in regulatory assets/liabilities		4			(28	)		(80	)		119
Settlements		(5	)		(48	)		(5	)		(66	)
Ending balance	$	171		$	267		$	171		$	267

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 and nine months ended September 30, 2023 and 2022.

Fair Value of Financial Instruments

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

	September 30, 2023				December 31, 2022
(millions)	Carrying Amount		Estimated Fair Value(1)		Carrying Amount		Estimated Fair Value(1)
Long-term debt(2)	$	3,726	$	3,438	$	3,725	$	3,614
Affiliated long-term debt(3)		230		230		230		230

(1)Fair value is estimated using market prices, where available, and interest rates currently available for issuance of debt with similar terms and remaining maturities. All fair value measurements are classified as Level 2. The carrying amount of debt issuances with short-term maturities and variable rates refinanced at current market rates is a reasonable estimate of their fair value.

(2)Carrying amount includes current portions presented in securities due within one year and amounts which represent the unamortized debt issuance costs and discount or premium.

(3)Carrying amount includes current portions presented in affiliated and related party payables.

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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. Components of net periodic benefit cost (credit) recorded by DESC were as follows:

(millions)	Pension Benefits						Other Postretirement Benefits
Three Months Ended September 30,	2023			2022			2023			2022
Service cost	$	2		$	2		$	—		$	—
Interest cost		8			5			2			1
Expected return on assets		(8	)		(12	)		—			—
Amortization of actuarial losses		3			1			(1	)		—
Net periodic benefit cost (credit)	$	5		$	(4	)	$	1		$	1
Nine Months Ended September 30,
Service cost	$	6		$	6		$	1		$	1
Interest cost		24			16			6			4
Expected return on assets		(25	)		(37	)		—			—
Amortization of actuarial losses		9			1			(3	)		—
Net periodic benefit cost (credit)	$	14		$	(14	)	$	4		$	5

During the three and nine months ended September 30, 2023, DESC made no contributions to its pension trust and does not expect to make any such contributions in 2023. 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.

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.

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,

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states may choose to develop regulatory programs that are more restrictive. Many of DESC’s facilities are subject to the CAA’s permitting and other requirements.

ACE Rule

In July 2019, the EPA published the final rule informally referred to as the ACE Rule, as a replacement for the Clean Power Plan. The ACE Rule regulated GHG emissions from existing coal-fired power plants pursuant to Section 111(d) of the CAA and required states to develop plans by July 2022 establishing unit-specific performance standards for existing coal-fired power plants. In January 2021, the U.S. Court of Appeals for the D.C. Circuit vacated the ACE Rule and remanded it to the EPA. This decision would take effect upon issuance of the court’s mandate. In March 2021, the court issued a partial mandate vacating and remanding all parts of the ACE Rule except for the portion of the ACE Rule that repealed the Clean Power Plan. In October 2021, the U.S. Supreme Court agreed to hear a challenge of the U.S. Court of Appeals for the D.C. Circuit’s decision on the ACE Rule. In June 2022, the U.S. Supreme Court reversed the D.C. Circuit’s decision on the ACE Rule and remanded the case back to the D.C. Circuit. In May 2023, the EPA proposed to repeal the ACE Rule as part of a package of proposed rules addressing CO2 emissions from new and existing fossil fuel-fired electric generating units. Until the EPA takes final action on this proposed rulemaking, DESC cannot predict an impact to its operations, financial condition and/or cash flows.

Carbon Regulations

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

In December 2018, the EPA proposed revised Standards of Performance for Greenhouse Gas Emissions from New, Modified, and Reconstructed Stationary Sources. The proposed rule would amend the previous determination that the best system of emission reduction for newly constructed coal-fired steam generating units is no longer partial carbon capture and storage. Instead, the proposed revised best system of emission reduction for this source category is the most efficient demonstrated steam cycle (e.g., supercritical steam conditions for large units and subcritical steam conditions for small units) in combination with best operating practices. The proposed revision to the performance standards for coal-fired steam generating units remains pending. 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

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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 extends the latest dates for compliance. Individual facilities’ compliance dates will vary based on circumstances and the determination by state regulators and may range from 2021 to 2028. While the impacts of this rule could be material to DESC’s results of operations, financial condition and/or cash flows, as DESC expects that wastewater treatment technology retrofits and modifications at the Williams and Wateree generating stations will be required, the existing regulatory framework in South Carolina provides rate recovery mechanisms that could substantially mitigate any such impacts for DESC.

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 SCDHEC BACT determination and modification of the station national pollutant discharge elimination system permit) 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 SCDHEC or the EPA. DESC anticipates that activities at these sites will continue through 2025 with a remaining estimated cost of $17 million. DESC expects to recover costs arising from the remediation work at all four sites through rate recovery mechanisms and as of September 30, 2023, deferred amounts, net of amounts previously recovered through rates and insurance settlements, totaled $41 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

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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. Until this matter is resolved and all phases of the CCR rule are promulgated, DESC is unable to precisely estimate potential incremental impacts or costs related to existing coal ash sites in connection with future implementation of the final CCR rule. In May 2023, the EPA released a proposed rule addressing one of the previously remanded provisions of the CCR 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. Until the EPA ultimately takes final action on this rulemaking, DESC is unable to predict whether or to what extent the new rules will ultimately require additional controls. While such amounts may 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.

Claims and Litigation

The following describes certain legal proceedings involving DESC relating primarily to events occurring before closing of the SCANA Combination. In addition, certain legal matters which have been resolved are discussed in Note 12 to the Consolidated Financial Statements in DESC’s Annual Report on Form 10-K for the year ended December 31, 2022. No reference to, or disclosure of, any proceeding, item or matter described below shall be construed as an admission or indication that such proceeding, item or matter is material. For certain of these matters, and unless otherwise noted therein, DESC is unable to estimate a reasonable range of possible loss and the related financial statement impacts, but for any such matter there could be a material impact to its results of operations, financial condition and/or cash flows. For the matters for which DESC is able to reasonably estimate a probable loss, the Consolidated Balance Sheets at September 30, 2023 and December 31, 2022 include reserves of $3 million and $94 million, respectively, and insurance receivables of $26 million and $68 million, respectively, included within other receivables. The balance at December 31, 2022 includes $68 million of offsetting reserves and insurance receivables related to personal injury or wrongful death cases which were pending. During both the three and nine months ended September 30, 2023 and 2022, charges included in DESC’s Consolidated Statements of Comprehensive Income were inconsequential.

Governmental Proceedings and Investigations

In June 2018, DESC received a notice of proposed assessment of approximately $410 million, excluding interest, from the SCDOR following its audit of DESC’s sales and use tax returns for the periods September 1, 2008 through December 31, 2017. The proposed assessment, which includes 100% of the NND Project, is based on the SCDOR’s position that DESC’s sales and use tax exemption for the NND Project does not apply because the facility will not become operational. In December 2020, the parties reached an agreement in principle in the amount of $165 million to resolve this matter. In June 2021, the parties executed a settlement agreement which allows DESC to fund the settlement amount through a combination of cash, shares of Dominion Energy common stock or real estate with an initial payment of at least $43 million in shares of Dominion Energy common stock. In August 2021, Dominion Energy issued 0.6 million shares of its common stock to satisfy DESC’s obligation for the initial payment under the settlement agreement. In May 2022, Dominion Energy issued an additional 0.9 million shares of its common stock to partially satisfy DESC’s remaining obligation under the settlement agreement. In June 2022, DESC requested approval from the South Carolina Commission to transfer certain real estate with a total settlement value of $51 million to satisfy its remaining obligation under the settlement agreement. In July 2022, the South Carolina Commission voted to approve the request and issued its final order in August 2022. In September 2022, DESC transferred certain non-utility property with a fair value of $28 million to the SCDOR under the settlement agreement. In December 2022, DESC transferred additional utility property with a fair value of $3 million to the SCDOR. In October 2022, DESC filed for approval to transfer the remaining real estate with FERC which was received in November 2022. In March 2023, DESC transferred utility property with a fair value of $10 million to the SCDOR resulting in a gain of $9 million ($7 million after-tax), recorded in other income, net in DESC's Consolidated Statements of Comprehensive Income for the nine months ended September 30, 2023. In June 2023, DESC transferred the remaining utility property with a fair value of $11 million to the SCDOR resulting in a gain of $11 million ($8 million after-tax), recorded in other income, net in DESC's Consolidated Statements of Comprehensive Income for the nine months ended September 30, 2023. In July 2023, DESC made a less than $1 million cash payment to the SCDOR to fully satisfy its remaining obligation, including applicable interest, under the settlement agreement.

Nuclear Operations

Nuclear Insurance

There have been no significant changes regarding DESC’s nuclear insurance as described in Note 12 to the Consolidated Financial Statements in DESC’s Annual Report on Form 10-K for the year ended December 31, 2022.

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11. OPERATING SEGMENTS

The Corporate and Other segment 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.

In the nine months ended September 30, 2023, DESC reported after-tax net income of $23 million in the Corporate and Other segment, including $21 million of after-tax net income for specific items all of which was attributable to its operating segment. In the nine months ended September 30, 2022, DESC reported an insignificant amount of specific items in the Corporate and Other segment.

The net income for specific items attributable to DESC’s operating segment in 2023 primarily related to a $31 million ($23 million after-tax) benefit related to real estate transactions, including gains on the transfer of property to satisfy litigation associated with the NND Project.

(millions)	External Revenue		Comprehensive Income (Loss) Available (Attributable) to Common Shareholder
Three Months Ended September 30, 2023
Dominion Energy South Carolina	$	848	$	137
Corporate and Other		—		4
Consolidated Total	$	848	$	141
Three Months Ended September 30, 2022
Dominion Energy South Carolina	$	1,083	$	169
Corporate and Other		—		(1	)
Consolidated Total	$	1,083	$	168
Nine Months Ended September 30, 2023
Dominion Energy South Carolina	$	2,311	$	286
Corporate and Other		—		23
Consolidated total	$	2,311	$	309
Nine Months Ended September 30, 2022
Dominion Energy South Carolina	$	2,841	$	392
Corporate and Other		—		(2	)
Consolidated total	$	2,841	$	390

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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, 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 September 30,				Nine Months Ended September 30,
(millions)	2023		2022		2023		2022
Direct and allocated costs from DES(1)	$	53	$	52	$	165	$	158
Operating Revenues - Electric from sales to affiliate		1		1		3		3
Operating Revenues - Gas from sales to affiliate		1		1		1		1
Operating Expenses - Other taxes from affiliate		2		1		7		6
Purchases of electricity from solar affiliates		5		5		11		12

(1)Includes capitalized expenditures of $15 million and $12 million for the three months ended September 30, 2023 and 2022, respectively and $44 million and $36 million for the nine months ended September 30, 2023 and 2022.

(millions)	September 30, 2023		December 31, 2022
Payable to Dominion Energy	$	2	$	1
Payable to DES		18		22
Payable to SCANA Corporation		7		7
Payable to Public Service Company of North Carolina, Incorporated		9		12
Payable to solar affiliates		1		—
Derivative assets with affiliates(1)		33		51

(1)Includes amounts recorded in other current assets of $4 million and $8 million as of September 30, 2023 and December 31, 2022, respectively, and amounts recorded in other deferred debits and other assets of $29 million and $43 million as of September 30, 2023 and December 31, 2022, respectively.

Borrowings from an affiliate are described in Note 5.

13. OTHER INCOME, NET

Components of other income, net are as follows:

	Three Months Ended September 30,						Nine Months Ended September 30,
(millions)	2023			2022			2023			2022
Other income	$	2		$	2		$	5		$	5
Other expense		(4	)		(1	)		(11	)		—
Gains on sales of assets(1)		—			20			32			37
Allowance for equity funds used during construction		—			1			—			4
Other income, net	$	(2	)	$	22		$	26		$	46

(1) Includes amounts recognized in connection with the transfer of property to satisfy litigation. See Note 10 for additional information.

In the second quarter of 2023, DESC completed the sale of certain utility property in South Carolina, as approved by the South Carolina Commission in February 2023, for total cash consideration of $11 million. In connection with the sale, DESC recognized a gain of $11 million ($8 million after-tax) for the nine months ended September 30, 2023.

In June 2022, DESC completed the sale of certain utility property in South Carolina, as approved by the South Carolina Commission in May 2022, for total cash consideration of $16 million. In connection with the sale, DESC recognized a gain of $16 million ($12 million after-tax) for the nine months ended September 30, 2022.

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ITEM 2. MANAGEMENT’S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS OF OPERATIONS

MD&A provides management’s narrative analysis of its consolidated results of operations. MD&A should be read in conjunction with DESC's Consolidated Financial Statements. DESC meets the conditions to file under the reduced disclosure format, and therefore has omitted certain sections of MD&A.

Forward-Looking Statements

This report contains statements concerning DESC’s expectations, plans, objectives, future financial performance and other statements that are not historical facts. These statements are “forward-looking statements.” In most cases, the reader can identify these forward-looking statements by such words as “anticipate,” “estimate,” “forecast,” “expect,” “believe,” “should,” “could,” “plan,” “may,” “continue,” “target” or other similar words.

DESC makes forward-looking statements with full knowledge that risks and uncertainties exist that may cause actual results to differ materially from predicted results. Factors that may cause actual results to differ are often presented with the forward-looking statements themselves. Additionally, other factors may cause actual results to differ materially from those indicated in any forward-looking statement. These factors include but are not limited to:

•Unusual weather conditions and their effect on energy sales to customers and energy commodity prices;

•Extreme weather events and other natural disasters, including, but not limited to, hurricanes, high winds, severe storms, earthquakes, flooding, climate changes and changes in water temperatures and availability that can cause outages and property damage to facilities;

•The impact of extraordinary external events, such as the current pandemic health event resulting from COVID-19, and their collateral consequences, including extended disruption of economic activity in our markets and global supply chains;

•Federal, state and local legislative and regulatory developments, including changes in or interpretations of federal and state tax laws and regulations;

•The direct and indirect impacts of Dominion Energy implementing recommendations resulting from its business review announced in November 2022;

•Risks of operating businesses in regulated industries that are subject to changing regulatory structures;

•Changes to regulated rates collected;

•Changes in future levels of domestic and international natural gas production, supply or consumption;

•Timing and receipt of regulatory approvals necessary for planned construction or growth projects and compliance with conditions associated with such regulatory approvals;

•The inability to complete planned construction, conversion or growth projects at all, or with the outcomes or within the terms and time frames initially anticipated, including as a result of increased public involvement, intervention or litigation in such projects;

•Changes to federal, state and local environmental laws and regulations, including those related to climate change, the tightening of emission or discharge limits for GHGs and other substances, more extensive permitting requirements and the regulation of additional substances;

•Cost of environmental strategy and compliance, including those costs related to climate change;

•Changes in implementation and enforcement practices of regulators relating to environmental standards and litigation exposure for remedial activities;

•Difficulty in anticipating mitigation requirements associated with environmental and other regulatory approvals or related appeals;

•The impact of operational hazards, including adverse developments with respect to pipeline and plant safety or integrity, equipment loss, malfunction or failure, operator error, and other catastrophic events;

•Risks associated with the operation of nuclear facilities, including costs associated with the disposal of spent nuclear fuel, decommissioning, plant maintenance and changes in existing regulations governing such facilities;

•Changes in operating, maintenance and construction costs;

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•Domestic terrorism and other threats to DESC’s physical and intangible assets, as well as threats to cybersecurity;

•Additional competition from the development and deployment of alternative energy sources, such as self-generation and distributed generation technologies;

•Competition in the development, construction and ownership of certain electric transmission facilities in connection with Order 1000;

•Changes in technology, particularly with respect to new, developing or alternative sources of generation and smart grid technologies;

•Changes in demand for services, including industrial, commercial and residential growth or decline in service areas, changes in supplies of natural gas delivered, changes in customer growth or usage patterns, including as a result of energy conservation programs, the availability of energy efficient devices and the use of distributed generation methods;

•Adverse outcomes in litigation matters or regulatory proceedings;

•Counterparty credit and performance risk;

•Fluctuations in the value of investments held in nuclear decommissioning and benefit plan trusts;

•Fluctuations in energy-related commodity prices and the effect these could have on DESC’s liquidity position and the underlying value of its assets;

•Fluctuations in interest rates;

•Changes in rating agency requirements or credit ratings and their effect on availability and cost of capital;

•Global capital market conditions, including the availability of credit and the ability to obtain financing on reasonable terms;

•Political and economic conditions, including inflation and deflation;

•Employee workforce factors including collective bargaining agreements and labor negotiations with union employees; and

•Changes in financial or regulatory accounting principles or policies imposed by governing bodies.

Additionally, other risks that could cause actual results to differ from predicted results are set forth in Part I. Item 1A. Risk Factors in DESC’s Annual Report on Form 10-K for the year ended December 31, 2022.

DESC’s forward-looking statements are based on beliefs and assumptions using information available at the time the statements are made. DESC cautions the reader not to place undue reliance on its forward-looking statements because the assumptions, beliefs, expectations and projections about future events may, and often do, differ materially from actual results. DESC undertakes no obligation to update any forward-looking statement to reflect developments occurring after the statement is made.

Results of Operations

Presented below is a summary of DESC’s results:

	Third Quarter							Year-To-Date
(millions)	2023		2022		$ Change			2023		2022		$ Change
Net income	$	146	$	173	$	(27	)	$	324	$	406	$	(82	)

Overview

Third Quarter 2023 vs. 2022

Net income decreased 16%, primarily due to a decrease in revenues from electric utility customers who previously elected to pay market based or other negotiated rates, the absence of a gain on the transfer of certain non-utility property and increased interest rates on borrowings, partially offset by an increase in sales to electric utility customers attributable to weather.

Year-To-Date 2023 vs. 2022

Net income decreased 20%, primarily due to a decrease in sales to electric utility customers attributable to weather and increased interest rates on borrowings.

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Analysis of Consolidated Operations

Presented below are selected amounts related to DESC’s results of operations:

	Third Quarter								Year-To-Date
(millions)	2023			2022		$ Change			2023		2022		$ Change
Operating revenues	$	848		$	1,083	$	(235	)	$	2,311	$	2,841	$	(530	)
Fuel used in electric generation		169			342		(173	)		454		770		(316	)
Purchased power		24			28		(4	)		60		86		(26	)
Gas purchased for resale		47			102		(55	)		174		296		(122	)
Other operations and maintenance		157			157		—			455		465		(10	)
Impairment of assets and other charges		—			2		(2	)		—		6		(6	)
Depreciation and amortization		135			127		8			395		378		17
Other taxes		69			72		(3	)		221		216		5
Other income, net		(2	)		22		(24	)		26		46		(20	)
Interest charges		64			57		7			186		162		24
Income tax expense		35			45		(10	)		68		102		(34	)

An analysis of DESC’s results of operations follows:

Third Quarter 2023 vs. 2022

Operating revenues decreased 22%, primarily reflecting:

•A $229 million decrease in fuel-related revenue as a result of a decrease in commodity costs and purchased power costs associated with sales to electric utility retail customers ($174 million) and gas utility customers ($55 million);

•A $16 million decrease from electric utility customers who previously elected to pay market based or other negotiated rates; and

•A $13 million decrease in sales to electric utility retail customers associated with economic and other usage factors; partially offset by

•A $19 million increase in sales to electric utility retail customers from an increase in cooling degree days during the cooling season; and

•A $11 million increase in sales to electric utility retail customers associated with growth.

Fuel used in electric generation decreased 51%, primarily due to decreased fuel costs associated with electric utility retail customers, which are offset in operating revenue and do not impact net income.

Gas purchased for resale decreased 54%, primarily due to a decrease in costs associated with gas utility customers, which are offset in operating revenue and do not impact net income.

Other income, net decreased $24 million, primarily due to the absence of a gain on the transfer of certain non-utility property ($19 million) and higher non-service costs related to pension and other postretirement benefits ($5 million).

Interest charges increased 12%, primarily due to higher interest rates on intercompany borrowings and commercial paper borrowings ($14 million), partially offset by lower interest expense due to higher debt AFUDC ($5 million).

Income tax expense decreased 22%, primarily due to lower pre-tax income.

Year-To-Date 2023 vs. 2022

Operating revenues decreased 19%, primarily reflecting:

•A $443 million decrease in fuel-related revenue as a result of a decrease in commodity costs and purchased power costs associated with sales to electric utility retail customers ($321 million) and gas utility customers ($122 million);

•A $41 million decrease in sales to electric utility retail customers from a decrease in heating degree days during the heating season ($26 million) and a decrease in cooling degree days during the cooling season ($15 million);

•A $39 million decrease from electric utility customers who previously elected to pay market based or other negotiated rates;

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•A $16 million decrease in the fuel cost component of off-system sales;

•A $13 million decrease in sales to electric utility retail customers associated with economic and other usage factors; and

•A $10 million decrease in sales to electric retail customers from the capital cost rider; partially offset by

•A $23 million increase in sales to electric utility retail customers associated with growth;

•A $9 million increase associated with increased infrastructure cost recovery under the Natural Gas Rate Stabilization Act; and

•A $5 million increase in sales to gas utility customers associated with growth.

Fuel used in electric generation decreased 41%, primarily due to decreased fuel costs associated with electric utility retail customers ($298 million) and a decrease in fuel costs associated with off-system sales ($16 million), which are offset in operating revenue and do not impact net income.

Purchased power decreased 30%, primarily due to a decrease in costs associated with electric utility customers, which are offset in operating revenue and do not impact net income.

Gas purchased for resale decreased 41%, primarily due to a decrease in costs associated with gas utility customers, which are offset in operating revenue and do not impact net income.

Other operations and maintenance decreased 2%, primarily due to a decrease in outside services ($9 million), partially offset by an increase in salaries, wages and benefits and administrative expenses ($7 million).

Other income, net decreased 43%, primarily due to higher non-service costs related to pension and other postretirement benefits ($15 million) and a decrease in gains from the sale of certain utility and non-utility property ($5 million).

Interest charges increased 15%, primarily due to higher interest rates on intercompany borrowings and commercial paper borrowings ($42 million), partially offset by lower interest expense due to higher debt AFUDC ($12 million).

Income tax expense decreased 33%, primarily due to lower pre-tax income ($29 million) and a benefit associated with the effective settlement of an uncertain tax position ($11 million).

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ITEM 4. CONTROLS AND PROCEDURES

Senior management of DESC, including DESC’s CEO and CFO, evaluated the effectiveness of DESC’s disclosure controls and procedures as of the end of the period covered by this report. Based on this evaluation process, DESC’s CEO and CFO have concluded that DESC’s disclosure controls and procedures are effective.

There were no changes that occurred during the last fiscal quarter that materially affected, or are reasonably likely to materially affect, DESC’s internal control over financial reporting.

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PART II. OTHER INFORMATION

ITEM 1. LEGAL PROCEEDINGS

From time to time, DESC is party to various legal, environmental or other regulatory proceedings, including in the ordinary course of business. SEC regulations require disclosure of certain environmental matters when a governmental authority is a party to the proceedings and such proceedings involve potential monetary sanctions that DESC reasonably believes will exceed a specified threshold. Pursuant to the SEC regulations, DESC uses a threshold of $1 million for such proceedings.

See the following for discussions on various legal, environmental and other regulatory proceedings to which DESC is a party, which information is incorporated herein by reference:

•Notes 3 and 12 to the Consolidated Financial Statements in DESC’s Annual Report on Form 10-K for the year ended December 31, 2022.

•Notes 2 and 10 to the Consolidated Financial Statements in this report.

ITEM 1A. RISK FACTORS

DESC’s business is influenced by many factors that are difficult to predict, involve uncertainties that may materially affect actual results and are often beyond its control. A number of these risk factors have been identified in DESC’s Annual Report on Form 10-K for the year ended December 31, 2022, which should be taken into consideration when reviewing the information contained in this report. There have been no material changes with regard to the risk factors previously disclosed in DESC's Annual Report on Form 10-K for the year ended December 31, 2022. For other factors that may cause actual results to differ materially from those indicated in any forward-looking statement or projection contained in this report, see Forward-Looking Statements in MD&A in this report.

ITEM 5. OTHER INFORMATION

During the last fiscal quarter, none of DESC’s directors or officers (as defined in Rule 16a-1(f) under the Exchange Act) adopted or terminated a “Rule 10b5-1 trading arrangement” or “non-Rule 10b5-1 trading arrangement,” as each term is defined in Item 408(a) of Regulation S-K.

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ITEM 6. EXHIBITS

Exhibit No.	Description
3.1	Amended and Restated Articles of Incorporation, effective April 29, 2019 (Exhibit 3.1, Form 8-K filed April 29, 2019, File No. 1-3375).
3.2	Amended and Restated Bylaws, effective April 29, 2019 (Exhibit 3.2, Form 8-K filed April 29, 2019, File No. 1-3375).
4.1	Dominion Energy South Carolina, Inc. agrees to furnish to the U.S. Securities and Exchange Commission upon request any instrument with respect to long-term debt as to which the total amount of securities authorized does not exceed 10% of its total consolidated assets.
31.a	Certification by Chief Executive Officer of Dominion Energy South Carolina, Inc. pursuant to Section 302 of the Sarbanes-Oxley Act of 2002 (filed herewith).
31.b	Certification by Chief Financial Officer of Dominion Energy South Carolina, Inc. pursuant to Section 302 of the Sarbanes-Oxley Act of 2002 (filed herewith).
32.a	Certification to the Securities and Exchange Commission by Chief Executive Officer and Chief Financial Officer of Dominion Energy South Carolina, Inc. as required by Section 906 of the Sarbanes-Oxley Act of 2002 (furnished herewith).
101	The following financial statements from Dominion Energy South Carolina, Inc.’s Quarterly Report on Form 10-Q for the quarter ended September 30, 2023, filed on November 8, 2023, formatted in iXBRL (Inline eXtensible Reporting Language): (i) Consolidated Balance Sheets, (ii) Consolidated Statements of Comprehensive Income, (iii) Consolidated Statements of Cash Flows, (iv) Consolidated Statements of Changes in Common Equity, and (v) the Notes to Consolidated Financial Statements.
104	Cover Page Interactive Data File (formatted in iXBRL (Inline eXtensible Reporting Language) and contained in Exhibit 101).

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SIGNATURE

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned thereunto duly authorized.

	DOMINION ENERGY SOUTH CAROLINA, INC.
		(Registrant)
	By:	/s/ Michele L. Cardiff
Date: November 8, 2023		Michele L. Cardiff
		Senior Vice President, Controller and Chief Accounting Officer

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EX-31.A

Exhibit 31.a

I, Diane Leopold, certify that:

1. I have reviewed this report on Form 10-Q of Dominion Energy South Carolina, Inc.;

2. Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;

3. Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this report;

4. The registrant's other certifying officer and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and have:

(a) Designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;

(b) Designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;

(c) Evaluated the effectiveness of the registrant's disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and

(d) Disclosed in this report any change in the registrant's internal control over financial reporting that occurred during the registrant's most recent fiscal quarter (the registrant's fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely to materially affect, the registrant's internal control over financial reporting; and

5. The registrant's other certifying officer and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the registrant's auditors and the audit committee of the registrant's board of directors (or persons performing the equivalent functions):

(a) All significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant's ability to record, process, summarize and report financial information; and

(b) Any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant's internal control over financial reporting.

Date: November 8, 2023	/s/ Diane Leopold
	Diane Leopold Chief Executive Officer

EX-31.B

Exhibit 31.b

I, Steven D. Ridge, certify that:

1. I have reviewed this report on Form 10-Q of Dominion Energy South Carolina, Inc.;

2. Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;

3. Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this report;

4. The registrant's other certifying officer and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and have:

(a) Designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;

(b) Designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;

(c) Evaluated the effectiveness of the registrant's disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and

(d) Disclosed in this report any change in the registrant's internal control over financial reporting that occurred during the registrant's most recent fiscal quarter (the registrant's fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely to materially affect, the registrant's internal control over financial reporting; and

5. The registrant's other certifying officer and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the registrant's auditors and the audit committee of the registrant's board of directors (or persons performing the equivalent functions):

(a) All significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant's ability to record, process, summarize and report financial information; and

(b) Any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant's internal control over financial reporting.

Date: November 8, 2023	/s/ Steven D. Ridge
	Steven D. Ridge Senior Vice President and Chief Financial Officer

EX-32.A

Exhibit 32.a

CERTIFICATION PURSUANT TO
18 U.S.C. SECTION 1350,
AS ADOPTED PURSUANT TO
SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

Pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, each of the undersigned officers of Dominion Energy South Carolina, Inc. (the “Company”), certify that:

1.the Quarterly Report on Form 10-Q for the quarter ended September 30, 2023 (the “Report”), of the Company to which this certification is an exhibit fully complies with the requirements of section 13(a) or 15(d) of the Securities Exchange Act of 1934 (15 U.S.C. 78m(a) or 78o(d)).

2.the information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Company as of September 30, 2023, and for the period then ended.

/s/ Diane Leopold

Diane Leopold
Chief Executive Officer
November 8, 2023

/s/ Steven D. Ridge

Steven D. Ridge
Senior Vice President and
Chief Financial Officer
November 8, 2023

XML

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2023	Nov. 02, 2023
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	2023
Document Fiscal Period Focus	Q3
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	400 OTARRE PARKWAY
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	Sep. 30, 2023

XML

Consolidated Balance Sheets (Unaudited) - USD ($) $ in Millions		Sep. 30, 2023	Dec. 31, 2022
ASSETS
Utility plant in service		$ 15,209	$ 14,688
Accumulated depreciation and amortization		(5,497)	(5,335)
Construction work in progress		616	541
Nuclear fuel, net of accumulated amortization		198	204
Utility plant, net		10,526	10,098
Nonutility Property and Investments:
Nonutility property, net of accumulated depreciation		27	20
Assets held in trust, nuclear decommissioning		230	223
Nonutility property and investments, net		257	243
Current Assets:
Cash and cash equivalents		8	11
Customer, net of allowance for uncollectible accounts of $7 and $5		405	420
Receivables, other		89	141
Inventories (at average cost):
Fuel		90	98
Gas stored		31	38
Materials and supplies		233	218
Prepayments		102	76
Regulatory assets		563	743
Other current assets	[1]	29	49
Current assets held for sale		0	8
Total current assets		1,550	1,804
Deferred Debits and Other Assets:
Regulatory assets		3,182	3,289
Other	[1]	261	315
Total deferred debits and other assets		3,443	3,604
Total assets		15,776	15,749
CAPITALIZATION AND LIABILITIES
Common Stock - no par value		4,088	4,088
Retained earnings		577	418
Accumulated other comprehensive loss		(2)	(2)
Total common equity		4,663	4,504
Noncontrolling interest		177	162
Total equity		4,840	4,666
Long-term debt, net		3,726	3,725
Affiliated long-term debt		0	230
Finance leases		4	6
Total long-term debt		3,730	3,961
Total capitalization		8,570	8,627
Current Liabilities:
Short-term borrowings		287	249
Securities due within one year		3	4
Accounts payable		133	297
Affiliated and related party payables		1,323	871
Customer deposits and customer prepayments		73	79
Taxes accrued		187	236
Interest accrued		66	75
Regulatory liabilities		212	251
Reserves for litigation and regulatory proceedings		3	94
Other		135	115
Total current liabilities		2,422	2,271
Deferred Credits and Other Liabilities:
Deferred income taxes and investment tax credits		1,249	1,230
Asset retirement obligations		689	628
Pension and other postretirement benefits		114	114
Regulatory liabilities		2,629	2,785
Affiliated liabilities		24	19
Other		79	75
Total deferred credits and other liabilities		4,784	4,851
Commitments and Contingencies
Total capitalization and liabilities		15,776	15,749
Related Party
Current Assets:
Affiliated and related party		$ 0	$ 2

[1] See Note 12 for amounts attributable to affiliates.

XML

Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) shares in Millions, $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Utility plant, net	$ 10,526	$ 10,098
Receivables, customer, allowance for uncollectible accounts	7	5
Total current assets	1,550	1,804
Total deferred debits and other assets	$ 3,443	$ 3,604
Common stock, par value	$ 0	$ 0
Common stock, shares outstanding	40.3	40.3
Variable Interest Entity, Primary Beneficiary [Member]
Utility plant, net	$ 726	$ 719
Total current assets	84	92
Total deferred debits and other assets	$ 26	$ 23

XML

Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Income Statement [Abstract]
Operating Revenue	[1]	$ 848	$ 1,083	$ 2,311	$ 2,841
Operating Expenses:
Fuel used in electric generation		169	342	454	770
Purchased power	[1]	24	28	60	86
Gas purchased for resale		47	102	174	296
Other operations and maintenance		119	117	334	343
Other operations and maintenance - affiliated suppliers		38	40	121	122
Impairment of assets and other charges		0	2	0	6
Depreciation and amortization		135	127	395	378
Other taxes	[1]	69	72	221	216
Total operating expenses		601	830	1,759	2,217
Operating income		247	253	552	624
Other income (expense), net		(2)	22	26	46
Interest charges, net of AFUDC	[1]	64	57	186	162
Income before income tax expense		181	218	392	508
Income tax expense		35	45	68	102
Net Income and Other Comprehensive Income		146	173	324	406
Comprehensive Income Attributable to Noncontrolling Interest		5	5	15	16
Comprehensive Income Available to Common Shareholder		$ 141	$ 168	$ 309	$ 390

[1] See Note 12 for amounts attributable to affiliates.

XML

Consolidated Statements of Comprehensive Income (Unaudited) (Parenthetical) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Income Statement [Abstract]
AFUDC	$ 6	$ 1	$ 15	$ 3

XML

Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Millions		9 Months Ended
		Sep. 30, 2023	Sep. 30, 2022
Operating Activities
Net income		$ 324	$ 406
Adjustments to reconcile net income to net cash provided by operating activities:
Impairment of assets and other charges		0	4
Deferred income taxes, net		19	201
Depreciation and amortization		395	378
Amortization of nuclear fuel		23	29
Gains on sale of assets		(32)	(37)
Other adjustments		8	3
Changes in certain assets and liabilities:
Receivables		29	(23)
Receivables - affiliated and related party		2	14
Inventories		0	(59)
Prepayments		(26)	(14)
Regulatory assets		197	(356)
Regulatory liabilities		(243)	(35)
Accounts payable		(95)	(5)
Accounts payable - affiliated and related party		(36)	56
Taxes accrued		(49)	(37)
Interest accrued		(9)	(5)
Pension and other postretirement benefits		0	(4)
Other assets and liabilities		75	(192)
Net cash provided by operating activities		582	324
Investing Activities
Property additions and construction expenditures		(706)	(514)
Proceeds from investments and sales of assets		(23)	(7)
Purchase of investments		(4)	(1)
Other		4	12
Net cash used in investing activities		(729)	(510)
Financing Activities
Dividend to parent		(150)	(348)
Short-term borrowings, net		38	250
Short-term borrowings - affiliated, net		258	239
Other		(2)	(3)
Net cash provided by financing activities		144	138
Net decrease in cash, restricted cash and equivalents		(3)	(48)
Cash, restricted cash and equivalents at beginning of period	[1]	11	54
Cash, restricted cash and equivalents at end of period	[1]	8	6
Significant noncash investing and financing activities:
Accrued construction expenditures	[2]	65	106
Operating leases	[2]	$ 2	$ 6

[1] Includes $24 million of restricted cash at December 31, 2021, recorded within other current assets on the Consolidated Balance Sheets. At September 30, 2023, September 30, 2022 and December 31, 2022 there were no restricted cash and equivalent balances.

[2] See Note 10 for noncash investing activities related to the transfer of property associated with the settlement of litigation.

XML

Consolidated Statements of Cash Flows (Unaudited) (Parenthetical) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022	Sep. 30, 2022	Dec. 31, 2021
Statement of Cash Flows [Abstract]
Restricted cash and equivalents	$ 0	$ 0	$ 0	$ 24

XML

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, 2021	$ 4,525	$ 4,016	$ 335	$ (1)	$ 175
Beginning balance (in shares) at Dec. 31, 2021		40
Total comprehensive income available to common shareholder	406		390		16
Capital contribution from parent	72	$ 72
Dividend to parent	(348)		(315)		(33)
Ending balance at Sep. 30, 2022	4,655	$ 4,088	410	(1)	158
Ending balance (in shares) at Sep. 30, 2022		40
Beginning balance at Jun. 30, 2022	4,612	$ 4,088	357	(1)	168
Beginning balance (in shares) at Jun. 30, 2022		40
Total comprehensive income available to common shareholder	173		168		5
Dividend to parent	(130)		(115)		(15)
Ending balance at Sep. 30, 2022	4,655	$ 4,088	410	(1)	158
Ending balance (in shares) at Sep. 30, 2022		40
Beginning balance at Dec. 31, 2022	4,666	$ 4,088	418	(2)	162
Beginning balance (in shares) at Dec. 31, 2022		40
Total comprehensive income available to common shareholder	324		309		15
Dividend to parent	(150)		(150)
Ending balance at Sep. 30, 2023	4,840	$ 4,088	577	(2)	177
Ending balance (in shares) at Sep. 30, 2023		40
Beginning balance at Jun. 30, 2023	4,744	$ 4,088	486	(2)	172
Beginning balance (in shares) at Jun. 30, 2023		40
Total comprehensive income available to common shareholder	146		141		5
Dividend to parent	(50)		(50)
Ending balance at Sep. 30, 2023	$ 4,840	$ 4,088	$ 577	$ (2)	$ 177
Ending balance (in shares) at Sep. 30, 2023		40

XML

Pay vs Performance Disclosure - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Pay vs Performance Disclosure
Net Income (Loss)	$ 141	$ 168	$ 309	$ 390

XML

Insider Trading Arrangements	9 Months Ended
	Sep. 30, 2023
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

XML

Summary of Significant Accounting Policies

9 Months Ended

Sep. 30, 2023

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, 2022 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, 2022, except as follows.

Asset Retirement Obligations

In the second quarter of 2023, DESC revised its estimated cash flow projections for AROs associated with certain previously retired coal-fired generating units. As a result, DESC recorded a $43 million increase to AROs with a corresponding increase to regulatory assets.

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Rate and Other Regulatory Matters

9 Months Ended

Sep. 30, 2023

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, 2022.

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 2023, 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 2023, along with a requested decrease to DESC's variable environmental and avoided capacity cost component. The net effect of the proposal is an annual increase of $176 million. In March 2023, DESC, the South Carolina Office of Regulatory Staff and another party of record filed a stipulation with the South Carolina Commission for approval to reduce the base fuel cost component reflecting a subsequent decrease in current fuel prices, resulting in a net annual increase of $121 million. In April 2023, the South Carolina Commission voted to approve the stipulation, with rates effective May 2023.

Electric Transmission Project

In March 2023, DESC filed an application with the South Carolina Commission requesting approval to construct and operate 19 miles of 230 kV transmission lines, a substation and associated facilities in Jasper County, South Carolina estimated to cost approximately $55 million. In July 2023, the South Carolina Commission voted to approve the request and issued its order in September 2023.

Electric – Other

DESC has approval for a DSM rider through which it recovers expenditures related to its DSM programs. In January 2023, 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 2023. In April 2023, the South Carolina Commission approved the request, effective with the first billing cycle of May 2023.

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 2023, DESC requested that the South Carolina Commission approve an adjustment to this rider to increase annual revenue by $24 million. In April 2023, the South Carolina Commission approved the request.

Natural Gas Base Rate Case

In March 2023, DESC filed its natural gas base rate case and schedules with the South Carolina Commission. DESC proposed a rate increase of $19 million effective October 2023. The base rate increase was proposed to recover significant investment in distribution infrastructure for the benefit of customers. The proposed rates would provide for an ROE of 10.38% compared to the currently authorized ROE of 10.25%. In addition, DESC elected to continue applicability of the Natural Gas Rate Stabilization Act, which allows for the adjustment of natural gas base rates annually, to its future rates and charges. In September 2023, DESC, the South Carolina Office of Regulatory Staff and other parties of record filed a stipulation agreement with the South Carolina Commission for approval. The stipulation agreement provides for a rate increase of $9 million commencing with bills rendered in October 2023, and an authorized ROE of 9.49%. Pursuant to the stipulation agreement, DESC would not file a natural gas base rate case prior to April 1, 2026, such that new rates would not be effective prior to October 1, 2026, absent unforeseen extraordinary economic or financial conditions that may include changes in corporate tax rates. In September 2023, the South Carolina Commission approved the stipulation agreement and issued its final order in October 2023.

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.

	September 30,		December 31,
(millions)	2023		2022
Regulatory assets:
NND Project costs(1)	$	138	$	138
AROs(2)		44		8
Deferred employee benefit plan costs(3)		11		4
Other unrecovered plant(4)		18		17
DSM programs(5)		20		21
Cost of fuel and purchased gas under-collections(6)		275		508
Other		57		47
Regulatory assets - current		563		743
NND Project costs(1)		1,984		2,088
AROs(2)		399		381
Deferred employee benefit plan costs(3)		145		161
Interest rate hedges(7)		168		169
Other unrecovered plant(4)		55		58
DSM programs(5)		43		41
Environmental remediation costs(8)		39		37
Deferred storm damage costs(9)		40		43
Deferred transmission operating costs(10)		74		75
Derivatives(11)		101		105
Other(12)		134		131
Regulatory assets - noncurrent		3,182		3,289
Total regulatory assets	$	3,745	$	4,032
Regulatory liabilities:
Monetization of guaranty settlement(13)	$	67	$	67
Income taxes refundable through future rates(14)		36		34
Reserve for refunds to electric utility customers(15)		87		100
Derivatives(11)		21		43
Other		1		7
Regulatory liabilities - current		212		251
Monetization of guaranty settlement(13)		652		702
Income taxes refundable through future rates(14)		847		871
Asset removal costs(16)		645		596
Reserve for refunds to electric utility customers(15)		261		325
Derivatives(11)		218		276
Other		6		15
Regulatory liabilities - noncurrent		2,629		2,785
Total regulatory liabilities	$	2,841	$	3,036

(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.

(3)Employee benefit plan costs have historically been recovered as they have been recorded under GAAP. Deferred employee benefit plan costs represent amounts of pension and other postretirement benefit costs which were accrued as liabilities and treated as regulatory assets pursuant to FERC guidance, and costs deferred pursuant to specific South Carolina Commission regulatory orders. DESC expects to recover deferred pension costs through utility rates over periods through 2044. DESC expects to recover other deferred benefit costs through utility rates, primarily over average service periods of participating employees up to 11 years.

(4)Represents the carrying value of coal-fired generating units, including related materials and supplies inventory, retired from service prior to being fully depreciated. DESC is amortizing these amounts through cost of service rates following depreciation amounts that were designed to recover the retired units cost over their previous estimated remaining useful lives, which has been estimated to be through 2025. Based on

current projections of remaining decommissioning costs, projected recovery is expected to extend through 2033. 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 over five years related to the transition or conversion from coal to gas fired generation at certain facilities.

(5)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 the changes in fair value and payments made or received upon settlement of certain interest rate derivatives designated as cash flow hedges. The amounts recorded are 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 29 years. See Note 10 for additional information.

(9)Represents storm restoration costs for which DESC expects to receive future recovery through customer rates over approximately 10 years pursuant to the settlement agreement approved in DESC’s retail electric base rate case. 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 recovery from customers through future rates over approximately 42 years pursuant to the settlement agreement approved in DESC’s retail electric base rate case. Unamortized amounts are included in rate base and earning a current return. See Note 12 to the Consolidated Financial Statements in DESC’s Annual Report on Form 10-K for the year ended December 31, 2022.

(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 2047.

(13)Represents proceeds related to the monetization of the Toshiba Settlement. In accordance with the SCANA Merger Approval Order, this balance, net of amounts that may be required to satisfy liens, will be refunded to electric customers over a 20-year period ending in 2039.

(14)Includes (i) excess deferred income taxes arising from the remeasurement of deferred income taxes in connection with the enactment of the 2017 Tax Reform Act (certain of which are protected under normalization rules and will be amortized over the remaining lives of related property, and certain of which will be amortized to the benefit of customers over prescribed periods as instructed by regulators) and (ii) deferred income taxes arising from investment tax credits, offset by (iii) deferred income taxes that arise from utility operations that have not been included in customer rates (a portion of which relate to depreciation and are expected to be recovered over the remaining lives of the related property which may range up to 85 years). See Note 7 to the Consolidated Financial Statements in DESC’s Annual Report on Form 10-K for the year ended December 31, 2022 for additional information.

(15)Reflects amounts previously collected from retail electric customers of DESC for the NND Project to be credited to customers over an estimated 11-year period effective February 2019 in connection with the SCANA Merger Approval Order.

(16)Represents estimated net collections through depreciation rates of amounts to be expended for the removal of assets in the future.

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

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Revenue Recognition

9 Months Ended

Sep. 30, 2023

Revenue from Contract with Customer [Abstract]

Revenue Recognition

3. REVENUE RECOGNITION

DESC has disaggregated operating revenues by customer class as follows:

	Quarter-to-Date September 30, 2023				Quarter-to-Date September 30, 2022				Year-to-Date September 30, 2023				Year-to-Date September 30, 2022
(millions)	Electric		Gas		Electric		Gas		Electric		Gas		Electric		Gas
Customer class:
Residential	$	382	$	34	$	433	$	39	$	910	$	186	$	1,065	$	193
Commercial		238		23		294		41		633		90		740		124
Industrial		94		19		153		54		282		56		396		128
Other		41		8		56		4		114		18		156		16
Revenues from contracts with customers		755		84		936		138		1,939		350		2,357		461
Other revenues		9		—		8		1		21		1		22		1
Total Operating Revenues	$	764	$	84	$	944	$	139	$	1,960	$	351	$	2,379	$	462

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 $7 million and $12 million at September 30, 2023 and

December 31, 2022, respectively. During the nine months ended September 30, 2023 and 2022, DESC recognized revenue of $9 million and $6 million, respectively, from the beginning contract liability balances as DESC fulfilled its obligations to provide service to its customers. Contract liabilities are recorded in customer deposits and customer prepayments in the Consolidated Balance Sheets.

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

	Regulatory Assets
(millions)	September 30, 2023		December 31, 2022
Beginning balance	$	9	$	11
Amortization		—		(2	)
Ending balance	$	9	$	9

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Equity

9 Months Ended

Sep. 30, 2023

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.

In May 2022, Dominion Energy issued $72 million of shares of Dominion Energy common stock to partially satisfy DESC’s remaining obligation under a settlement agreement with the SCDOR discussed in Note 10. In connection with this transaction, DESC recorded an equity contribution from Dominion Energy in the second quarter of 2022.

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, 2022.

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Long-Term and Short-Term Debt

9 Months Ended

Sep. 30, 2023

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 $6.0 billion joint revolving credit facility, which can be used for working capital, as support for the combined commercial paper programs of DESC, Dominion Energy, Virginia Power and Questar Gas, 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, 2022.

At September 30, 2023, 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	$	287	$	—

(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, Virginia Power and Questar Gas. 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 September 30, 2023, the sub-limit for DESC was $500 million. If DESC has liquidity needs in excess of its sub-limit, the sub-limit may be changed or such needs may be satisfied through short-term intercompany borrowings from Dominion Energy. This credit facility matures in June 2026, with the potential to be extended by the borrowers to June 2028. The credit facility can be used to support bank borrowings and the issuance of commercial paper, as well as to support up to $1.0 billion (or the sub-limit, whichever is less) of letters of credit.

In March 2023, FERC granted DESC authority through March 2025 to issue short-term indebtedness (pursuant to Section 204 of the Federal Power Act) in amounts not to exceed $2.2 billion outstanding with maturity dates of one year or less. In addition, in March 2023, FERC granted GENCO authority through March 2025 to issue short-term indebtedness not to exceed $200 million outstanding with maturity dates of one year or less.

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 September 30, 2023 and December 31, 2022, DESC, GENCO and Fuel Company collectively had borrowings outstanding under these agreements totaling $1.0 billion and $769 million, respectively, which are recorded in affiliated and related party payables in DESC’s Consolidated Balance Sheets. Interest charges associated with these agreements were $16 million and $4 million for the three months ended September 30, 2023 and 2022, respectively, and $44 million and $9 million for the nine months ended September 30, 2023 and 2022, respectively.

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 2024.

In October 2023, DESC issued $500 million of 6.25% first mortgage bonds that mature in 2053 with proceeds used for general corporate purposes and to repay short-term borrowings, including borrowings under DESC's intercompany credit facility with Dominion Energy.

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Income Taxes

9 Months Ended

Sep. 30, 2023

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:

Nine Months Ended September 30,	2023			2022
U.S. statutory rate		21.0	%		21.0	%
Increases (reductions) resulting from:
State taxes, net of federal benefit		4.1			4.0
Reversal of excess deferred income taxes		(4.8	)		(4.5	)
Allowance for equity funds used during construction		—			(0.2	)
Settlements of uncertain tax positions		(2.7	)		—
Other, net		(0.2	)		(0.2	)
Effective tax rate		17.4	%		20.1	%

As of September 30, 2023, DESC’s effective tax rate reflects an income tax benefit of $11 million from the effective settlement of a position that management believed was reasonably possible to occur. Otherwise, there have been no material changes in DESC’s unrecognized tax benefits. See Note 7 to the Consolidated Financial Statements in DESC's Annual Report on Form 10-K for the year ended December 31, 2022 for a discussion of these unrecognized tax benefits.

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Derivative Financial Instruments

9 Months Ended

Sep. 30, 2023

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, 2022. 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. 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 September 30, 2023 and December 31, 2022, DESC would have been required to post $— 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, non-derivative contracts and derivatives elected under the normal purchases and normal sales exception, per contractual terms. DESC had posted $1 million of collateral at both September 30, 2023 and December 31, 2022 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 September 30, 2023 and December 31, 2022 was $1 million and $2 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. DESC’s commodity derivative assets are not subject to a master netting agreement or similar arrangement.

	September 30, 2023								December 31, 2022
	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		Financial Instruments		Cash Collateral Received		Net Amounts		Gross Assets Presented in the Consolidated Balance Sheet		Financial Instruments		Cash Collateral Received		Net Amounts
Interest rate contracts:
Over-the-counter	$	2	$	—	$	—	$	2	$	1	$	—	$	—	$	1
Total derivatives	$	2	$	—	$	—	$	2	$	1	$	—	$	—	$	1

	September 30, 2023								December 31, 2022
	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		Financial Instruments		Cash Collateral Paid		Net Amounts		Gross Liabilities Presented in the Consolidated Balance Sheet		Financial Instruments		Cash Collateral Paid		Net Amounts
Interest rate contracts:
Over-the-counter	$	1	$	—	$	1	$	—	$	2	$	—	$	1	$	1
Total derivatives	$	1	$	—	$	1	$	—	$	2	$	—	$	1	$	1

Volumes

The following table presents the volume of derivative activity at September 30, 2023. These volumes are based on open derivative positions and represent the combined absolute value of their long and short positions.

	Current		Noncurrent
Electricity (MWh in millions):
Fixed price		2		22
Interest rate(1)(in millions)	$	—	$	71

(1)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:

(millions)	Fair Value - Derivatives under Hedge Accounting		Fair Value - Derivatives not under Hedge Accounting		Total Fair Value
At September 30, 2023
ASSETS
Current Assets
Commodity	$	—	$	18	$	18
Total current derivative assets(1)		—		18		18
Noncurrent Assets
Commodity		—		153		153
Interest rate		—		2		2
Total noncurrent derivative assets(2)		—		155		155
Total derivative assets	$	—	$	173	$	173
LIABILITIES
Noncurrent Liabilities
Interest rate		—		1		1
Total noncurrent derivative liabilities(3)		—		1		1
Total derivative liabilities	$	—	$	1	$	1
At December 31, 2022
ASSETS
Current Assets
Commodity	$	—	$	41	$	41
Total current derivative assets(1)		—		41		41
Noncurrent Assets
Commodity		—		210		210
Interest rate		—		1		1
Total noncurrent derivative assets(2)		—		211		211
Total derivative assets	$	—	$	252	$	252
LIABILITIES
Noncurrent Liabilities
Interest rate		2		—		2
Total noncurrent derivative liabilities(3)		2		—		2
Total derivative liabilities	$	2	$	—	$	2

(1)Current derivative assets are presented in other current assets in DESC’s Consolidated Balance Sheets.

(2)Noncurrent derivative assets are presented in other deferred debits and other assets in DESC’s Consolidated Balance Sheets.

(3)Noncurrent derivative liabilities are presented in other deferred credits and other liabilities in DESC’s Consolidated Balance Sheets.

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)
Three Months Ended September 30,	2023		2022
Derivative type and location of gains (losses):
Interest rate	$	—	$	2
Total	$	—	$	2
Nine Months Ended September 30,
Derivative type and location of gains (losses):
Interest rate	$	—	$	10
Total	$	—	$	10

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

Derivatives Not Designated as Hedging Instruments

(millions)	Amount of Gain (Loss) Recognized in Income on Derivatives(1)
Three Months Ended September 30,	2023			2022
Derivative type and location of gains (losses):
Commodity:
Purchased power	$	4		$	48
Interest rate:
Interest charges		—			(1	)
Total	$	4		$	47
Nine Months Ended September 30,
Derivative type and location of gains (losses):
Commodity:
Purchased power	$	4		$	66
Interest rate:
Interest charges		(1	)		(2	)
Total	$	3		$	64

(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.

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Fair Value Measurements, Including Derivatives

9 Months Ended

Sep. 30, 2023

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, 2022. 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 September 30, 2023. The range and weighted average are presented in dollars for market price inputs.

	Fair Value (millions)		Valuation Techniques	Unobservable Input		Range	Weighted Average(1)
Assets
Physical forwards:
Electricity	$	171	Discounted cash flow	Market price (per MWh)	(2)	25-92	48
Total assets	$	171

(1)Averages weighted by volume.

(2)Represents market prices beyond defined terms for Levels 1 and 2.

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)

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 September 30, 2023
Assets
Commodity	$	—	$	—	$	171	$	171
Interest rate		—		2		—		2
Total assets	$	—	$	2	$	171	$	173
Liabilities
Interest rate	$	—	$	1	$	—	$	1
Total liabilities	$	—	$	1	$	—	$	1
At December 31, 2022
Assets
Commodity	$	—	$	—	$	251	$	251
Interest rate		—		1		—		1
Total assets	$	—	$	1	$	251	$	252
Liabilities
Interest rate	$	—	$	2	$	—	$	2
Total liabilities	$	—	$	2	$	—	$	2

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						Nine Months Ended
	September 30,						September 30,
	2023			2022			2023			2022
(millions)
Beginning balance	$	167		$	295		$	251		$	148
Total realized and unrealized gains (losses):
Included in earnings:
Purchased power		5			48			5			66
Included in regulatory assets/liabilities		4			(28	)		(80	)		119
Settlements		(5	)		(48	)		(5	)		(66	)
Ending balance	$	171		$	267		$	171		$	267

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 and nine months ended September 30, 2023 and 2022.

Fair Value of Financial Instruments

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

	September 30, 2023				December 31, 2022
(millions)	Carrying Amount		Estimated Fair Value(1)		Carrying Amount		Estimated Fair Value(1)
Long-term debt(2)	$	3,726	$	3,438	$	3,725	$	3,614
Affiliated long-term debt(3)		230		230		230		230

(1)Fair value is estimated using market prices, where available, and interest rates currently available for issuance of debt with similar terms and remaining maturities. All fair value measurements are classified as Level 2. The carrying amount of debt issuances with short-term maturities and variable rates refinanced at current market rates is a reasonable estimate of their fair value.

(2)Carrying amount includes current portions presented in securities due within one year and amounts which represent the unamortized debt issuance costs and discount or premium.

(3)Carrying amount includes current portions presented in affiliated and related party payables.

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Employee Benefit Plans

9 Months Ended

Sep. 30, 2023

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. Components of net periodic benefit cost (credit) recorded by DESC were as follows:

(millions)	Pension Benefits						Other Postretirement Benefits
Three Months Ended September 30,	2023			2022			2023			2022
Service cost	$	2		$	2		$	—		$	—
Interest cost		8			5			2			1
Expected return on assets		(8	)		(12	)		—			—
Amortization of actuarial losses		3			1			(1	)		—
Net periodic benefit cost (credit)	$	5		$	(4	)	$	1		$	1
Nine Months Ended September 30,
Service cost	$	6		$	6		$	1		$	1
Interest cost		24			16			6			4
Expected return on assets		(25	)		(37	)		—			—
Amortization of actuarial losses		9			1			(3	)		—
Net periodic benefit cost (credit)	$	14		$	(14	)	$	4		$	5

During the three and nine months ended September 30, 2023, DESC made no contributions to its pension trust and does not expect to make any such contributions in 2023. 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.

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Commitments And Contingencies

9 Months Ended

Sep. 30, 2023

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.

Environmental Matters

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

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

Air

The CAA, as amended, is a comprehensive program utilizing a broad range of regulatory tools to protect and preserve the nation's air quality. At a minimum, states are required to establish regulatory programs to meet applicable requirements of the CAA. However,

states may choose to develop regulatory programs that are more restrictive. Many of DESC’s facilities are subject to the CAA’s permitting and other requirements.

ACE Rule

In July 2019, the EPA published the final rule informally referred to as the ACE Rule, as a replacement for the Clean Power Plan. The ACE Rule regulated GHG emissions from existing coal-fired power plants pursuant to Section 111(d) of the CAA and required states to develop plans by July 2022 establishing unit-specific performance standards for existing coal-fired power plants. In January 2021, the U.S. Court of Appeals for the D.C. Circuit vacated the ACE Rule and remanded it to the EPA. This decision would take effect upon issuance of the court’s mandate. In March 2021, the court issued a partial mandate vacating and remanding all parts of the ACE Rule except for the portion of the ACE Rule that repealed the Clean Power Plan. In October 2021, the U.S. Supreme Court agreed to hear a challenge of the U.S. Court of Appeals for the D.C. Circuit’s decision on the ACE Rule. In June 2022, the U.S. Supreme Court reversed the D.C. Circuit’s decision on the ACE Rule and remanded the case back to the D.C. Circuit. In May 2023, the EPA proposed to repeal the ACE Rule as part of a package of proposed rules addressing CO2 emissions from new and existing fossil fuel-fired electric generating units. Until the EPA takes final action on this proposed rulemaking, DESC cannot predict an impact to its operations, financial condition and/or cash flows.

Carbon Regulations

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

In December 2018, the EPA proposed revised Standards of Performance for Greenhouse Gas Emissions from New, Modified, and Reconstructed Stationary Sources. The proposed rule would amend the previous determination that the best system of emission reduction for newly constructed coal-fired steam generating units is no longer partial carbon capture and storage. Instead, the proposed revised best system of emission reduction for this source category is the most efficient demonstrated steam cycle (e.g., supercritical steam conditions for large units and subcritical steam conditions for small units) in combination with best operating practices. The proposed revision to the performance standards for coal-fired steam generating units remains pending. 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 extends the latest dates for compliance. Individual facilities’ compliance dates will vary based on circumstances and the determination by state regulators and may range from 2021 to 2028. While the impacts of this rule could be material to DESC’s results of operations, financial condition and/or cash flows, as DESC expects that wastewater treatment technology retrofits and modifications at the Williams and Wateree generating stations will be required, the existing regulatory framework in South Carolina provides rate recovery mechanisms that could substantially mitigate any such impacts for DESC.

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 SCDHEC BACT determination and modification of the station national pollutant discharge elimination system permit) 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 SCDHEC or the EPA. DESC anticipates that activities at these sites will continue through 2025 with a remaining estimated cost of $17 million. DESC expects to recover costs arising from the remediation work at all four sites through rate recovery mechanisms and as of September 30, 2023, deferred amounts, net of amounts previously recovered through rates and insurance settlements, totaled $41 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. Until this matter is resolved and all phases of the CCR rule are promulgated, DESC is unable to precisely estimate potential incremental impacts or costs related to existing coal ash sites in connection with future implementation of the final CCR rule. In May 2023, the EPA released a proposed rule addressing one of the previously remanded provisions of the CCR 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. Until the EPA ultimately takes final action on this rulemaking, DESC is unable to predict whether or to what extent the new rules will ultimately require additional controls. While such amounts may 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.

Claims and Litigation

The following describes certain legal proceedings involving DESC relating primarily to events occurring before closing of the SCANA Combination. In addition, certain legal matters which have been resolved are discussed in Note 12 to the Consolidated Financial Statements in DESC’s Annual Report on Form 10-K for the year ended December 31, 2022. No reference to, or disclosure of, any proceeding, item or matter described below shall be construed as an admission or indication that such proceeding, item or matter is material. For certain of these matters, and unless otherwise noted therein, DESC is unable to estimate a reasonable range of possible loss and the related financial statement impacts, but for any such matter there could be a material impact to its results of operations, financial condition and/or cash flows. For the matters for which DESC is able to reasonably estimate a probable loss, the Consolidated Balance Sheets at September 30, 2023 and December 31, 2022 include reserves of $3 million and $94 million, respectively, and insurance receivables of $26 million and $68 million, respectively, included within other receivables. The balance at December 31, 2022 includes $68 million of offsetting reserves and insurance receivables related to personal injury or wrongful death cases which were pending. During both the three and nine months ended September 30, 2023 and 2022, charges included in DESC’s Consolidated Statements of Comprehensive Income were inconsequential.

Governmental Proceedings and Investigations

In June 2018, DESC received a notice of proposed assessment of approximately $410 million, excluding interest, from the SCDOR following its audit of DESC’s sales and use tax returns for the periods September 1, 2008 through December 31, 2017. The proposed assessment, which includes 100% of the NND Project, is based on the SCDOR’s position that DESC’s sales and use tax exemption for the NND Project does not apply because the facility will not become operational. In December 2020, the parties reached an agreement in principle in the amount of $165 million to resolve this matter. In June 2021, the parties executed a settlement agreement which allows DESC to fund the settlement amount through a combination of cash, shares of Dominion Energy common stock or real estate with an initial payment of at least $43 million in shares of Dominion Energy common stock. In August 2021, Dominion Energy issued 0.6 million shares of its common stock to satisfy DESC’s obligation for the initial payment under the settlement agreement. In May 2022, Dominion Energy issued an additional 0.9 million shares of its common stock to partially satisfy DESC’s remaining obligation under the settlement agreement. In June 2022, DESC requested approval from the South Carolina Commission to transfer certain real estate with a total settlement value of $51 million to satisfy its remaining obligation under the settlement agreement. In July 2022, the South Carolina Commission voted to approve the request and issued its final order in August 2022. In September 2022, DESC transferred certain non-utility property with a fair value of $28 million to the SCDOR under the settlement agreement. In December 2022, DESC transferred additional utility property with a fair value of $3 million to the SCDOR. In October 2022, DESC filed for approval to transfer the remaining real estate with FERC which was received in November 2022. In March 2023, DESC transferred utility property with a fair value of $10 million to the SCDOR resulting in a gain of $9 million ($7 million after-tax), recorded in other income, net in DESC's Consolidated Statements of Comprehensive Income for the nine months ended September 30, 2023. In June 2023, DESC transferred the remaining utility property with a fair value of $11 million to the SCDOR resulting in a gain of $11 million ($8 million after-tax), recorded in other income, net in DESC's Consolidated Statements of Comprehensive Income for the nine months ended September 30, 2023. In July 2023, DESC made a less than $1 million cash payment to the SCDOR to fully satisfy its remaining obligation, including applicable interest, under the settlement agreement.

Nuclear Operations

Nuclear Insurance

There have been no significant changes regarding DESC’s nuclear insurance as described in Note 12 to the Consolidated Financial Statements in DESC’s Annual Report on Form 10-K for the year ended December 31, 2022.

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Operating Segments

9 Months Ended

Sep. 30, 2023

Segment Reporting [Abstract]

Operating Segments

11. OPERATING SEGMENTS

The Corporate and Other segment 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.

In the nine months ended September 30, 2023, DESC reported after-tax net income of $23 million in the Corporate and Other segment, including $21 million of after-tax net income for specific items all of which was attributable to its operating segment. In the nine months ended September 30, 2022, DESC reported an insignificant amount of specific items in the Corporate and Other segment.

The net income for specific items attributable to DESC’s operating segment in 2023 primarily related to a $31 million ($23 million after-tax) benefit related to real estate transactions, including gains on the transfer of property to satisfy litigation associated with the NND Project.

(millions)	External Revenue		Comprehensive Income (Loss) Available (Attributable) to Common Shareholder
Three Months Ended September 30, 2023
Dominion Energy South Carolina	$	848	$	137
Corporate and Other		—		4
Consolidated Total	$	848	$	141
Three Months Ended September 30, 2022
Dominion Energy South Carolina	$	1,083	$	169
Corporate and Other		—		(1	)
Consolidated Total	$	1,083	$	168
Nine Months Ended September 30, 2023
Dominion Energy South Carolina	$	2,311	$	286
Corporate and Other		—		23
Consolidated total	$	2,311	$	309
Nine Months Ended September 30, 2022
Dominion Energy South Carolina	$	2,841	$	392
Corporate and Other		—		(2	)
Consolidated total	$	2,841	$	390

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Affiliated and Related Party Transactions

9 Months Ended

Sep. 30, 2023

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, 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 September 30,				Nine Months Ended September 30,
(millions)	2023		2022		2023		2022
Direct and allocated costs from DES(1)	$	53	$	52	$	165	$	158
Operating Revenues - Electric from sales to affiliate		1		1		3		3
Operating Revenues - Gas from sales to affiliate		1		1		1		1
Operating Expenses - Other taxes from affiliate		2		1		7		6
Purchases of electricity from solar affiliates		5		5		11		12

(1)Includes capitalized expenditures of $15 million and $12 million for the three months ended September 30, 2023 and 2022, respectively and $44 million and $36 million for the nine months ended September 30, 2023 and 2022.

(millions)	September 30, 2023		December 31, 2022
Payable to Dominion Energy	$	2	$	1
Payable to DES		18		22
Payable to SCANA Corporation		7		7
Payable to Public Service Company of North Carolina, Incorporated		9		12
Payable to solar affiliates		1		—
Derivative assets with affiliates(1)		33		51

(1)Includes amounts recorded in other current assets of $4 million and $8 million as of September 30, 2023 and December 31, 2022, respectively, and amounts recorded in other deferred debits and other assets of $29 million and $43 million as of September 30, 2023 and December 31, 2022, respectively.

Borrowings from an affiliate are described in Note 5.

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Other Income, Net

9 Months Ended

Sep. 30, 2023

Income Statement [Abstract]

Other Income, Net

13. OTHER INCOME, NET

Components of other income, net are as follows:

	Three Months Ended September 30,						Nine Months Ended September 30,
(millions)	2023			2022			2023			2022
Other income	$	2		$	2		$	5		$	5
Other expense		(4	)		(1	)		(11	)		—
Gains on sales of assets(1)		—			20			32			37
Allowance for equity funds used during construction		—			1			—			4
Other income, net	$	(2	)	$	22		$	26		$	46

(1) Includes amounts recognized in connection with the transfer of property to satisfy litigation. See Note 10 for additional information.

In the second quarter of 2023, DESC completed the sale of certain utility property in South Carolina, as approved by the South Carolina Commission in February 2023, for total cash consideration of $11 million. In connection with the sale, DESC recognized a gain of $11 million ($8 million after-tax) for the nine months ended September 30, 2023.

In June 2022, DESC completed the sale of certain utility property in South Carolina, as approved by the South Carolina Commission in May 2022, for total cash consideration of $16 million. In connection with the sale, DESC recognized a gain of $16 million ($12 million after-tax) for the nine months ended September 30, 2022.

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Summary of Significant Accounting Policies (Policies)

9 Months Ended

Sep. 30, 2023

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, 2022 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, 2022, except as follows.

Asset Retirement Obligations

Asset Retirement Obligations

In the second quarter of 2023, DESC revised its estimated cash flow projections for AROs associated with certain previously retired coal-fired generating units. As a result, DESC recorded a $43 million increase to AROs with a corresponding increase to regulatory assets.

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Rate and Other Regulatory Matters (Tables)

9 Months Ended

Sep. 30, 2023

Regulated Operations [Abstract]

Schedule of Regulatory Assets and Liabilities

	September 30,		December 31,
(millions)	2023		2022
Regulatory assets:
NND Project costs(1)	$	138	$	138
AROs(2)		44		8
Deferred employee benefit plan costs(3)		11		4
Other unrecovered plant(4)		18		17
DSM programs(5)		20		21
Cost of fuel and purchased gas under-collections(6)		275		508
Other		57		47
Regulatory assets - current		563		743
NND Project costs(1)		1,984		2,088
AROs(2)		399		381
Deferred employee benefit plan costs(3)		145		161
Interest rate hedges(7)		168		169
Other unrecovered plant(4)		55		58
DSM programs(5)		43		41
Environmental remediation costs(8)		39		37
Deferred storm damage costs(9)		40		43
Deferred transmission operating costs(10)		74		75
Derivatives(11)		101		105
Other(12)		134		131
Regulatory assets - noncurrent		3,182		3,289
Total regulatory assets	$	3,745	$	4,032
Regulatory liabilities:
Monetization of guaranty settlement(13)	$	67	$	67
Income taxes refundable through future rates(14)		36		34
Reserve for refunds to electric utility customers(15)		87		100
Derivatives(11)		21		43
Other		1		7
Regulatory liabilities - current		212		251
Monetization of guaranty settlement(13)		652		702
Income taxes refundable through future rates(14)		847		871
Asset removal costs(16)		645		596
Reserve for refunds to electric utility customers(15)		261		325
Derivatives(11)		218		276
Other		6		15
Regulatory liabilities - noncurrent		2,629		2,785
Total regulatory liabilities	$	2,841	$	3,036

(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.

(3)Employee benefit plan costs have historically been recovered as they have been recorded under GAAP. Deferred employee benefit plan costs represent amounts of pension and other postretirement benefit costs which were accrued as liabilities and treated as regulatory assets pursuant to FERC guidance, and costs deferred pursuant to specific South Carolina Commission regulatory orders. DESC expects to recover deferred pension costs through utility rates over periods through 2044. DESC expects to recover other deferred benefit costs through utility rates, primarily over average service periods of participating employees up to 11 years.

(4)Represents the carrying value of coal-fired generating units, including related materials and supplies inventory, retired from service prior to being fully depreciated. DESC is amortizing these amounts through cost of service rates following depreciation amounts that were designed to recover the retired units cost over their previous estimated remaining useful lives, which has been estimated to be through 2025. Based on

current projections of remaining decommissioning costs, projected recovery is expected to extend through 2033. 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 over five years related to the transition or conversion from coal to gas fired generation at certain facilities.

(5)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 the changes in fair value and payments made or received upon settlement of certain interest rate derivatives designated as cash flow hedges. The amounts recorded are 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 29 years. See Note 10 for additional information.

(9)Represents storm restoration costs for which DESC expects to receive future recovery through customer rates over approximately 10 years pursuant to the settlement agreement approved in DESC’s retail electric base rate case. 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 recovery from customers through future rates over approximately 42 years pursuant to the settlement agreement approved in DESC’s retail electric base rate case. Unamortized amounts are included in rate base and earning a current return. See Note 12 to the Consolidated Financial Statements in DESC’s Annual Report on Form 10-K for the year ended December 31, 2022.

(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 2047.

(13)Represents proceeds related to the monetization of the Toshiba Settlement. In accordance with the SCANA Merger Approval Order, this balance, net of amounts that may be required to satisfy liens, will be refunded to electric customers over a 20-year period ending in 2039.

(14)Includes (i) excess deferred income taxes arising from the remeasurement of deferred income taxes in connection with the enactment of the 2017 Tax Reform Act (certain of which are protected under normalization rules and will be amortized over the remaining lives of related property, and certain of which will be amortized to the benefit of customers over prescribed periods as instructed by regulators) and (ii) deferred income taxes arising from investment tax credits, offset by (iii) deferred income taxes that arise from utility operations that have not been included in customer rates (a portion of which relate to depreciation and are expected to be recovered over the remaining lives of the related property which may range up to 85 years). See Note 7 to the Consolidated Financial Statements in DESC’s Annual Report on Form 10-K for the year ended December 31, 2022 for additional information.

(15)Reflects amounts previously collected from retail electric customers of DESC for the NND Project to be credited to customers over an estimated 11-year period effective February 2019 in connection with the SCANA Merger Approval Order.

(16)Represents estimated net collections through depreciation rates of amounts to be expended for the removal of assets in the future.

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Revenue Recognition (Tables)

9 Months Ended

Sep. 30, 2023

Revenue from Contract with Customer [Abstract]

Disaggregation of Revenue

DESC has disaggregated operating revenues by customer class as follows:

	Quarter-to-Date September 30, 2023				Quarter-to-Date September 30, 2022				Year-to-Date September 30, 2023				Year-to-Date September 30, 2022
(millions)	Electric		Gas		Electric		Gas		Electric		Gas		Electric		Gas
Customer class:
Residential	$	382	$	34	$	433	$	39	$	910	$	186	$	1,065	$	193
Commercial		238		23		294		41		633		90		740		124
Industrial		94		19		153		54		282		56		396		128
Other		41		8		56		4		114		18		156		16
Revenues from contracts with customers		755		84		936		138		1,939		350		2,357		461
Other revenues		9		—		8		1		21		1		22		1
Total Operating Revenues	$	764	$	84	$	944	$	139	$	1,960	$	351	$	2,379	$	462

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)	September 30, 2023		December 31, 2022
Beginning balance	$	9	$	11
Amortization		—		(2	)
Ending balance	$	9	$	9

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Long-Term and Short-Term Debt (Tables)

9 Months Ended

Sep. 30, 2023

Debt Disclosure [Abstract]

Schedule of Line of Credit Facilities

At September 30, 2023, 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	$	287	$	—

(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, Virginia Power and Questar Gas. 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 September 30, 2023, the sub-limit for DESC was $500 million. If DESC has liquidity needs in excess of its sub-limit, the sub-limit may be changed or such needs may be satisfied through short-term intercompany borrowings from Dominion Energy. This credit facility matures in June 2026, with the potential to be extended by the borrowers to June 2028. The credit facility can be used to support bank borrowings and the issuance of commercial paper, as well as to support up to $1.0 billion (or the sub-limit, whichever is less) of letters of credit.

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Income Taxes (Tables)

9 Months Ended

Sep. 30, 2023

Income Tax Disclosure [Abstract]

Schedule of Effective Income Tax Rate Reconciliation

Nine Months Ended September 30,	2023			2022
U.S. statutory rate		21.0	%		21.0	%
Increases (reductions) resulting from:
State taxes, net of federal benefit		4.1			4.0
Reversal of excess deferred income taxes		(4.8	)		(4.5	)
Allowance for equity funds used during construction		—			(0.2	)
Settlements of uncertain tax positions		(2.7	)		—
Other, net		(0.2	)		(0.2	)
Effective tax rate		17.4	%		20.1	%

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Derivative Financial Instruments (Tables)

9 Months Ended

Sep. 30, 2023

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. DESC’s commodity derivative assets are not subject to a master netting agreement or similar arrangement.

	September 30, 2023								December 31, 2022
	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		Financial Instruments		Cash Collateral Received		Net Amounts		Gross Assets Presented in the Consolidated Balance Sheet		Financial Instruments		Cash Collateral Received		Net Amounts
Interest rate contracts:
Over-the-counter	$	2	$	—	$	—	$	2	$	1	$	—	$	—	$	1
Total derivatives	$	2	$	—	$	—	$	2	$	1	$	—	$	—	$	1

Offsetting Liabilities

	September 30, 2023								December 31, 2022
	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		Financial Instruments		Cash Collateral Paid		Net Amounts		Gross Liabilities Presented in the Consolidated Balance Sheet		Financial Instruments		Cash Collateral Paid		Net Amounts
Interest rate contracts:
Over-the-counter	$	1	$	—	$	1	$	—	$	2	$	—	$	1	$	1
Total derivatives	$	1	$	—	$	1	$	—	$	2	$	—	$	1	$	1

Schedule of Volume of Derivative Activity

The following table presents the volume of derivative activity at September 30, 2023. These volumes are based on open derivative positions and represent the combined absolute value of their long and short positions.

	Current		Noncurrent
Electricity (MWh in millions):
Fixed price		2		22
Interest rate(1)(in millions)	$	—	$	71

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:

(millions)	Fair Value - Derivatives under Hedge Accounting		Fair Value - Derivatives not under Hedge Accounting		Total Fair Value
At September 30, 2023
ASSETS
Current Assets
Commodity	$	—	$	18	$	18
Total current derivative assets(1)		—		18		18
Noncurrent Assets
Commodity		—		153		153
Interest rate		—		2		2
Total noncurrent derivative assets(2)		—		155		155
Total derivative assets	$	—	$	173	$	173
LIABILITIES
Noncurrent Liabilities
Interest rate		—		1		1
Total noncurrent derivative liabilities(3)		—		1		1
Total derivative liabilities	$	—	$	1	$	1
At December 31, 2022
ASSETS
Current Assets
Commodity	$	—	$	41	$	41
Total current derivative assets(1)		—		41		41
Noncurrent Assets
Commodity		—		210		210
Interest rate		—		1		1
Total noncurrent derivative assets(2)		—		211		211
Total derivative assets	$	—	$	252	$	252
LIABILITIES
Noncurrent Liabilities
Interest rate		2		—		2
Total noncurrent derivative liabilities(3)		2		—		2
Total derivative liabilities	$	2	$	—	$	2

(1)Current derivative assets are presented in other current assets in DESC’s Consolidated Balance Sheets.

(2)Noncurrent derivative assets are presented in other deferred debits and other assets in DESC’s Consolidated Balance Sheets.

(3)Noncurrent derivative liabilities are presented in other deferred credits and other liabilities in DESC’s Consolidated Balance Sheets.

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)
Three Months Ended September 30,	2023		2022
Derivative type and location of gains (losses):
Interest rate	$	—	$	2
Total	$	—	$	2
Nine Months Ended September 30,
Derivative type and location of gains (losses):
Interest rate	$	—	$	10
Total	$	—	$	10

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

Derivatives Not Designated as Hedging Instruments

Derivatives Not Designated as Hedging Instruments

(millions)	Amount of Gain (Loss) Recognized in Income on Derivatives(1)
Three Months Ended September 30,	2023			2022
Derivative type and location of gains (losses):
Commodity:
Purchased power	$	4		$	48
Interest rate:
Interest charges		—			(1	)
Total	$	4		$	47
Nine Months Ended September 30,
Derivative type and location of gains (losses):
Commodity:
Purchased power	$	4		$	66
Interest rate:
Interest charges		(1	)		(2	)
Total	$	3		$	64

(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.

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Fair Value Measurements, Including Derivatives (Tables)

9 Months Ended

Sep. 30, 2023

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 September 30, 2023. The range and weighted average are presented in dollars for market price inputs.

	Fair Value (millions)		Valuation Techniques	Unobservable Input		Range	Weighted Average(1)
Assets
Physical forwards:
Electricity	$	171	Discounted cash flow	Market price (per MWh)	(2)	25-92	48
Total assets	$	171

(1)Averages weighted by volume.

(2)Represents market prices beyond defined terms for Levels 1 and 2.

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)

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 September 30, 2023
Assets
Commodity	$	—	$	—	$	171	$	171
Interest rate		—		2		—		2
Total assets	$	—	$	2	$	171	$	173
Liabilities
Interest rate	$	—	$	1	$	—	$	1
Total liabilities	$	—	$	1	$	—	$	1
At December 31, 2022
Assets
Commodity	$	—	$	—	$	251	$	251
Interest rate		—		1		—		1
Total assets	$	—	$	1	$	251	$	252
Liabilities
Interest rate	$	—	$	2	$	—	$	2
Total liabilities	$	—	$	2	$	—	$	2

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						Nine Months Ended
	September 30,						September 30,
	2023			2022			2023			2022
(millions)
Beginning balance	$	167		$	295		$	251		$	148
Total realized and unrealized gains (losses):
Included in earnings:
Purchased power		5			48			5			66
Included in regulatory assets/liabilities		4			(28	)		(80	)		119
Settlements		(5	)		(48	)		(5	)		(66	)
Ending balance	$	171		$	267		$	171		$	267

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:

	September 30, 2023				December 31, 2022
(millions)	Carrying Amount		Estimated Fair Value(1)		Carrying Amount		Estimated Fair Value(1)
Long-term debt(2)	$	3,726	$	3,438	$	3,725	$	3,614
Affiliated long-term debt(3)		230		230		230		230

(1)Fair value is estimated using market prices, where available, and interest rates currently available for issuance of debt with similar terms and remaining maturities. All fair value measurements are classified as Level 2. The carrying amount of debt issuances with short-term maturities and variable rates refinanced at current market rates is a reasonable estimate of their fair value.

(2)Carrying amount includes current portions presented in securities due within one year and amounts which represent the unamortized debt issuance costs and discount or premium.

(3)Carrying amount includes current portions presented in affiliated and related party payables.

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Employee Benefit Plans (Tables)

9 Months Ended

Sep. 30, 2023

Retirement Benefits [Abstract]

Components of Net Periodic Benefit Cost (Credit)

(millions)	Pension Benefits						Other Postretirement Benefits
Three Months Ended September 30,	2023			2022			2023			2022
Service cost	$	2		$	2		$	—		$	—
Interest cost		8			5			2			1
Expected return on assets		(8	)		(12	)		—			—
Amortization of actuarial losses		3			1			(1	)		—
Net periodic benefit cost (credit)	$	5		$	(4	)	$	1		$	1
Nine Months Ended September 30,
Service cost	$	6		$	6		$	1		$	1
Interest cost		24			16			6			4
Expected return on assets		(25	)		(37	)		—			—
Amortization of actuarial losses		9			1			(3	)		—
Net periodic benefit cost (credit)	$	14		$	(14	)	$	4		$	5

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Operating Segments (Tables)

9 Months Ended

Sep. 30, 2023

Segment Reporting [Abstract]

Schedule of Segment Reporting Information, by Segment

(millions)	External Revenue		Comprehensive Income (Loss) Available (Attributable) to Common Shareholder
Three Months Ended September 30, 2023
Dominion Energy South Carolina	$	848	$	137
Corporate and Other		—		4
Consolidated Total	$	848	$	141
Three Months Ended September 30, 2022
Dominion Energy South Carolina	$	1,083	$	169
Corporate and Other		—		(1	)
Consolidated Total	$	1,083	$	168
Nine Months Ended September 30, 2023
Dominion Energy South Carolina	$	2,311	$	286
Corporate and Other		—		23
Consolidated total	$	2,311	$	309
Nine Months Ended September 30, 2022
Dominion Energy South Carolina	$	2,841	$	392
Corporate and Other		—		(2	)
Consolidated total	$	2,841	$	390

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Affiliated and Related Party Transactions (Tables)

9 Months Ended

Sep. 30, 2023

Related Party Transactions [Abstract]

Schedule of Affiliated Transactions

Amounts expensed are primarily recorded in other operations and maintenance - affiliated suppliers and other income, net in the Consolidated Statements of Comprehensive Income.

	Three Months Ended September 30,				Nine Months Ended September 30,
(millions)	2023		2022		2023		2022
Direct and allocated costs from DES(1)	$	53	$	52	$	165	$	158
Operating Revenues - Electric from sales to affiliate		1		1		3		3
Operating Revenues - Gas from sales to affiliate		1		1		1		1
Operating Expenses - Other taxes from affiliate		2		1		7		6
Purchases of electricity from solar affiliates		5		5		11		12

(1)Includes capitalized expenditures of $15 million and $12 million for the three months ended September 30, 2023 and 2022, respectively and $44 million and $36 million for the nine months ended September 30, 2023 and 2022.

Schedule of Affiliated Transactions

(millions)	September 30, 2023		December 31, 2022
Payable to Dominion Energy	$	2	$	1
Payable to DES		18		22
Payable to SCANA Corporation		7		7
Payable to Public Service Company of North Carolina, Incorporated		9		12
Payable to solar affiliates		1		—
Derivative assets with affiliates(1)		33		51

(1)Includes amounts recorded in other current assets of $4 million and $8 million as of September 30, 2023 and December 31, 2022, respectively, and amounts recorded in other deferred debits and other assets of $29 million and $43 million as of September 30, 2023 and December 31, 2022, respectively.

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Other Income, Net (Tables)

9 Months Ended

Sep. 30, 2023

Income Statement [Abstract]

Components of Other Income, Net

Components of other income, net are as follows:

	Three Months Ended September 30,						Nine Months Ended September 30,
(millions)	2023			2022			2023			2022
Other income	$	2		$	2		$	5		$	5
Other expense		(4	)		(1	)		(11	)		—
Gains on sales of assets(1)		—			20			32			37
Allowance for equity funds used during construction		—			1			—			4
Other income, net	$	(2	)	$	22		$	26		$	46

(1) Includes amounts recognized in connection with the transfer of property to satisfy litigation. See Note 10 for additional information.

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Summary of Significant Accounting Policies - Additional Information (Details) $ in Millions	3 Months Ended
	Jun. 30, 2023 USD ($)
Accounting Policies [Abstract]
Increase in asset retirement obligations	$ 43

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Rate and Other Regulatory Matters (Narrative) (Detail) - USD ($) $ in Millions	1 Months Ended				9 Months Ended
	Sep. 30, 2023	Apr. 30, 2023	Mar. 31, 2023	Jan. 31, 2023	Sep. 30, 2023	Feb. 28, 2023
Rate And Other Regulatory Matters [Line Items]
South Carolina Commission Order for Increase/Decrease of Total Fuel Cost Component of Retail Electric Rates to produce a projected under-recovery						$ 176
Annual increase (decrease) in pension cost rider		$ 24
Estimated electric transmission cost			$ 55
Amount of increase in proposed base rate	$ 9		$ 19
Percentage of currently authorized ROE	9.49%		10.25%
Percentage of proposed ROE			10.38%
Regulatory asset recovery assessment end period					2047
Storm restoration recovery period					10 years
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 not designed, amortized to interest, 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					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					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					2033
Advanced Metering Infrastructure Project [Member]
Rate And Other Regulatory Matters [Line Items]
New expected amortization of carrying value of coal-fired generating unit					2028
Demand Side Management Programs [Member]
Rate And Other Regulatory Matters [Line Items]
Recovery period of regulatory asset	3 years				3 years
Asset Retirement Obligation Costs [Member]
Rate And Other Regulatory Matters [Line Items]
Recovery period of regulatory asset	105 years				105 years
Environmental Remediation Costs [Member]
Rate And Other Regulatory Matters [Line Items]
Recovery period of regulatory asset	29 years				29 years
Deferred Transmission Operating Costs [Member]
Rate And Other Regulatory Matters [Line Items]
Recovery period of regulatory asset	42 years				42 years
Rider D S M [Member]
Rate And Other Regulatory Matters [Line Items]
South Carolina Commission Order, Annual DSM Program Rate Rider Recovery Amount				$ 46
South Carolina Commission [Member]
Rate And Other Regulatory Matters [Line Items]
South Carolina Commission Order for Increase/Decrease of Total Fuel Cost Component of Retail Electric Rates to produce a projected under-recovery		$ 121

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Rate and Other Regulatory Matters (Schedule of Regulatory Assets) (Detail) - USD ($) $ in Millions		Sep. 30, 2023	Dec. 31, 2022
Regulatory Assets
Regulatory assets, current		$ 563	$ 743
Regulatory assets, noncurrent		3,182	3,289
Total regulatory assets		3,745	4,032
NND Project Costs [Member]
Regulatory Assets
Regulatory assets, current	[1]	138	138
Regulatory assets, noncurrent	[1]	1,984	2,088
Deferred Employee Benefit Plan Costs [Member]
Regulatory Assets
Regulatory assets, current	[2]	11	4
Regulatory assets, noncurrent	[2]	145	161
Interest Rate Hedges [Member]
Regulatory Assets
Regulatory assets, noncurrent	[3]	168	169
Other Unrecovered Plant [Member]
Regulatory Assets
Regulatory assets, current	[4]	18	17
Regulatory assets, noncurrent	[4]	55	58
Demand Side Management Programs [Member]
Regulatory Assets
Regulatory assets, current	[5]	20	21
Regulatory assets, noncurrent	[5]	43	41
Other Regulatory Assets [Member]
Regulatory Assets
Regulatory assets, current		57	47
Regulatory assets, noncurrent	[6]	134	131
Cost of Fuel and Purchased Gas Under-Collections [Member]
Regulatory Assets
Regulatory assets, current	[7]	275	508
Asset Retirement Obligation Costs [Member]
Regulatory Assets
Regulatory assets, current	[8]	44	8
Regulatory assets, noncurrent	[8]	399	381
Environmental Remediation Costs [Member]
Regulatory Assets
Regulatory assets, noncurrent	[9]	39	37
Deferred Storm Damage Costs [Member]
Regulatory Assets
Regulatory assets, noncurrent	[10]	40	43
Deferred Transmission Operating Costs [Member]
Regulatory Assets
Regulatory assets, noncurrent	[11]	74	75
Derivative [Member]
Regulatory Assets
Regulatory assets, noncurrent	[12]	$ 101	$ 105

[1] Reflects expenditures associated with the NND Project, which pursuant to the SCANA Merger Approval Order, will be recovered from electric service customers over a 20-year period ending in 2039.

[2] Employee benefit plan costs have historically been recovered as they have been recorded under GAAP. Deferred employee benefit plan costs represent amounts of pension and other postretirement benefit costs which were accrued as liabilities and treated as regulatory assets pursuant to FERC guidance, and costs deferred pursuant to specific South Carolina Commission regulatory orders. DESC expects to recover deferred pension costs through utility rates over periods through 2044. DESC expects to recover other deferred benefit costs through utility rates, primarily over average service periods of participating employees up to 11 years.

[3] Represents the changes in fair value and payments made or received upon settlement of certain interest rate derivatives designated as cash flow hedges. The amounts recorded are expected to be amortized to interest expense over the lives of the underlying debt through 2065.

[4] Represents the carrying value of coal-fired generating units, including related materials and supplies inventory, retired from service prior to being fully depreciated. DESC is amortizing these amounts through cost of service rates following depreciation amounts that were designed to recover the retired units cost over their previous estimated remaining useful lives, which has been estimated to be through 2025. Based on current projections of remaining decommissioning costs, projected recovery is expected to extend through 2033. 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 over five years related to the transition or conversion from coal to gas fired generation at certain facilities.

[5] 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] Various other regulatory assets are expected to be recovered through rates over varying periods through 2047.

[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] 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.

[9] Reflects amounts associated with the assessment and clean-up of sites currently or formerly owned by DESC. Such remediation costs are expected to be recovered over periods of up to 29 years. See Note 10 for additional information.

[10] Represents storm restoration costs for which DESC expects to receive future recovery through customer rates over approximately 10 years pursuant to the settlement agreement approved in DESC’s retail electric base rate case. Unamortized amounts are included in rate base and are earning a current return.

[11] Includes deferred depreciation and property taxes associated with certain transmission assets for which DESC expects recovery from customers through future rates over approximately 42 years pursuant to the settlement agreement approved in DESC’s retail electric base rate case. Unamortized amounts are included in rate base and earning a current return. See Note 12 to the Consolidated Financial Statements in DESC’s Annual Report on Form 10-K for the year ended December 31, 2022.

[12] Represents changes in the fair value of derivatives, excluding separately presented interest rate hedges, that following settlement are expected to be recovered from or refunded to customers.

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Rate and Other Regulatory Matters (Schedule of Regulatory Liabilities) (Detail) - USD ($) $ in Millions		Sep. 30, 2023	Dec. 31, 2022
Regulatory Liabilities
Regulatory liability, current		$ 212	$ 251
Regulatory liability, noncurrent		2,629	2,785
Total regulatory liabilities		2,841	3,036
Monetization Of Guaranty Settlement [Member]
Regulatory Liabilities
Regulatory liability, current	[1]	67	67
Regulatory liability, noncurrent	[1]	652	702
Income Taxes Refundable Through Future Rates [Member]
Regulatory Liabilities
Regulatory liability, current	[2]	36	34
Regulatory liability, noncurrent	[2]	847	871
Reserve For Refunds To Electric Utility Customers [Member]
Regulatory Liabilities
Regulatory liability, current	[3]	87	100
Regulatory liability, noncurrent	[3]	261	325
Other Regulatory Liability [Member]
Regulatory Liabilities
Regulatory liability, current		1	7
Regulatory liability, noncurrent		6	15
Asset Removal Costs [Member]
Regulatory Liabilities
Regulatory liability, noncurrent	[4]	645	596
Derivative [Member]
Regulatory Liabilities
Regulatory liability, current	[5]	21	43
Regulatory liability, noncurrent	[5]	$ 218	$ 276

[1] Represents proceeds related to the monetization of the Toshiba Settlement. In accordance with the SCANA Merger Approval Order, this balance, net of amounts that may be required to satisfy liens, will be refunded to electric customers over a 20-year period ending in 2039.

[2] Includes (i) excess deferred income taxes arising from the remeasurement of deferred income taxes in connection with the enactment of the 2017 Tax Reform Act (certain of which are protected under normalization rules and will be amortized over the remaining lives of related property, and certain of which will be amortized to the benefit of customers over prescribed periods as instructed by regulators) and (ii) deferred income taxes arising from investment tax credits, offset by (iii) deferred income taxes that arise from utility operations that have not been included in customer rates (a portion of which relate to depreciation and are expected to be recovered over the remaining lives of the related property which may range up to 85 years). See Note 7 to the Consolidated Financial Statements in DESC’s Annual Report on Form 10-K for the year ended December 31, 2022 for additional information.

[3] 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.

[4] Represents estimated net collections through depreciation rates of amounts to be expended for the removal of assets in the future.

[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.

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Revenue Recognition (Disaggregation of Revenue) (Detail) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Total Operating Revenues	[1]	$ 848	$ 1,083	$ 2,311	$ 2,841
Electric Operations
Operating revenue from contracts with customers		755	936	1,939	2,357
Other revenues		9	8	21	22
Total Operating Revenues		764	944	1,960	2,379
Gas Distribution
Operating revenue from contracts with customers		84	138	350	461
Other revenues			1	1	1
Total Operating Revenues		84	139	351	462
Residential | Electric Operations
Operating revenue from contracts with customers		382	433	910	1,065
Residential | Gas Distribution
Operating revenue from contracts with customers		34	39	186	193
Commercial | Electric Operations
Operating revenue from contracts with customers		238	294	633	740
Commercial | Gas Distribution
Operating revenue from contracts with customers		23	41	90	124
Industrial | Electric Operations
Operating revenue from contracts with customers		94	153	282	396
Industrial | Gas Distribution
Operating revenue from contracts with customers		19	54	56	128
Other | Electric Operations
Operating revenue from contracts with customers		41	56	114	156
Other | Gas Distribution
Operating revenue from contracts with customers		$ 8	$ 4	$ 18	$ 16

[1] See Note 12 for amounts attributable to affiliates.

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Revenue Recognition (Narrative) (Detail) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Revenue from Contract with Customer [Abstract]
Contract liability balances	$ 7		$ 12
Revenue recognized from contract liability balances	$ 9	$ 6

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Revenue Recognition (Balance and Activity Related to Contract Costs Deferred as Regulatory Assets) (Detail) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2023	Dec. 31, 2022
Revenues [Abstract]
Beginning balance	$ 9	$ 11
Amortization	0	(2)
Ending balance	$ 9	$ 9

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Equity (Narrative) (Detail) - USD ($) $ in Millions	1 Months Ended
	May 31, 2022	Sep. 30, 2023	Dec. 31, 2022
Class Of Stock [Line Items]
Common stock, par value
Common stock, shares authorized		50,000,000	50,000,000
Common stock, shares issued		40,300,000	40,300,000
Common stock, shares outstanding		40,300,000	40,300,000
Preferred stock, par value
Preferred stock, shares authorized		20,000,000	20,000,000
Preferred stock, shares issued		1,000	1,000
Preferred stock, shares outstanding		1,000	1,000
Dominion Energy | SCDOR | Common Stock
Class Of Stock [Line Items]
Common stock issued to satisfy the settlement	$ 72

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Long-Term and Short-Term Debt (Narrative) (Detail) - USD ($)		1 Months Ended		3 Months Ended		9 Months Ended
		Oct. 31, 2023	Mar. 31, 2023	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Debt Instrument [Line Items]
Commercial paper borrowing limit			$ 2,200,000,000
Affiliated and related party payables and other				$ 135,000,000		$ 135,000,000		$ 115,000,000
Interest charges	[1]			64,000,000	$ 57,000,000	186,000,000	$ 162,000,000
Maximum [Member]
Debt Instrument [Line Items]
Short term commercial paper maturity period			1 year
Genco
Debt Instrument [Line Items]
Commercial paper borrowing limit			$ 200,000,000
Genco | Maximum [Member]
Debt Instrument [Line Items]
Short term commercial paper maturity period			1 year
Dominion Energy
Debt Instrument [Line Items]
Affiliated and related party payables and other				1,000,000,000		1,000,000,000		$ 769,000,000
Interest charges				16,000,000	$ 4,000,000	44,000,000	$ 9,000,000
Inter company credit facility maximum capacity				900,000,000		900,000,000
Dominion Energy | Senior Notes Due in 2025 | Subsequent Event
Debt Instrument [Line Items]
Total Long-term Debt		$ 500,000,000
Interest rate percentage		6.25%
Debt instrument maturity year		2053
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 | Dominion Energy
Debt Instrument [Line Items]
Maximum Facility Sub-Limit				6,000,000,000		6,000,000,000
Industrial Revenue Bonds
Debt Instrument [Line Items]
Total Long-term Debt				$ 68,000,000		$ 68,000,000

[1] See Note 12 for amounts attributable to affiliates.

[2] A maximum of $1.0 billion of the facility is available to DESC, assuming adequate capacity is available after giving effect to uses by co-borrowers Dominion Energy, Virginia Power and Questar Gas. 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 September 30, 2023, the sub-limit for DESC was $500 million. If DESC has liquidity needs in excess of its sub-limit, the sub-limit may be changed or such needs may be satisfied through short-term intercompany borrowings from Dominion Energy. This credit facility matures in June 2026, with the potential to be extended by the borrowers to June 2028. The credit facility can be used to support bank borrowings and the issuance of commercial paper, as well as to support up to $1.0 billion (or the sub-limit, whichever is less) of letters of credit.

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Long-Term and Short-Term Debt (Schedule of Line of Credit Facilities) (Detail) - Joint Revolving Credit Facility	Sep. 30, 2023 USD ($)	[1]
Debt Instrument [Line Items]
Maximum Facility Sub-Limit	$ 1,000,000,000
Outstanding Commercial Paper	287,000,000
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, Virginia Power and Questar Gas. 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 September 30, 2023, the sub-limit for DESC was $500 million. If DESC has liquidity needs in excess of its sub-limit, the sub-limit may be changed or such needs may be satisfied through short-term intercompany borrowings from Dominion Energy. This credit facility matures in June 2026, with the potential to be extended by the borrowers to June 2028. The credit facility can be used to support bank borrowings and the issuance of commercial paper, as well as to support up to $1.0 billion (or the sub-limit, whichever is less) of letters of credit.

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Long-Term and Short-Term Debt (Schedule of Line of Credit Facilities) (Parenthetical) (Detail)	9 Months Ended
	Sep. 30, 2023 USD ($)
Minimum [Member]
Debt Instrument [Line Items]
Line of credit facility maturity date	2026-06
Maximum [Member]
Debt Instrument [Line Items]
Line of credit facility maturity date	2028-06
Joint Revolving Credit Facility
Debt Instrument [Line Items]
Maximum Facility Sub-Limit	$ 1,000,000,000	[1]
Line of Credit Facility
Debt Instrument [Line Items]
Maximum Facility Sub-Limit	500,000,000
Letter of Credit
Debt Instrument [Line Items]
Maximum Facility Sub-Limit	$ 1,000,000,000

[1] A maximum of $1.0 billion of the facility is available to DESC, assuming adequate capacity is available after giving effect to uses by co-borrowers Dominion Energy, Virginia Power and Questar Gas. 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 September 30, 2023, the sub-limit for DESC was $500 million. If DESC has liquidity needs in excess of its sub-limit, the sub-limit may be changed or such needs may be satisfied through short-term intercompany borrowings from Dominion Energy. This credit facility matures in June 2026, with the potential to be extended by the borrowers to June 2028. The credit facility can be used to support bank borrowings and the issuance of commercial paper, as well as to support up to $1.0 billion (or the sub-limit, whichever is less) of letters of credit.

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Income Taxes - Schedule of Effective Income Tax Rate Reconciliation (Detail)	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Income Tax Disclosure [Abstract]
U.S. statutory rate	21.00%	21.00%
Increases (reductions) resulting from:
State taxes, net of federal benefit	4.10%	4.00%
Reversal of excess deferred income taxes	(4.80%)	(4.50%)
Allowance for equity funds used during construction	0.00%	(0.20%)
Settlements of uncertain tax positions	(2.70%)	0.00%
Other, net	(0.20%)	(0.20%)
Effective tax rate	17.40%	20.10%

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Income Taxes (Narrative) (Detail) $ in Millions	Sep. 30, 2023 USD ($)
Income Taxes [Line Items]
Income tax benefit reasonably possible to occur	$ 11

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Derivative Financial Instruments (Narrative) (Detail) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Derivative [Line Items]
Additional collateral to its counterparties	$ 0	$ 1
Collateral already posted	1	1
Fair value of derivative instruments with credit-related contingent provisions that are in liability position and not fully collateralized with cash	$ 1	$ 2

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Derivative Financial Instruments (Offsetting Assets and Liabilities) (Detail) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Assets
Derivative [Line Items]
Assets not offset in the consolidated balance sheet	$ 2	$ 1
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
Assets | Interest Rate Contract [Member] | Over The Counter [Member]
Derivative [Line Items]
Assets not offset in the consolidated balance sheet	2	1
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
Liability
Derivative [Line Items]
Gross liabilities presented in the consolidated balance sheet	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	1	1
Gross amounts not offset in the consolidated balance sheet, net amounts	0	1
Liability | Interest Rate Contract [Member] | Over The Counter [Member]
Derivative [Line Items]
Gross liabilities presented in the consolidated balance sheet	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	1	1
Gross amounts not offset in the consolidated balance sheet, net amounts	$ 0	$ 1

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Derivative Financial Instruments (Schedule of Volume of Derivative Activity) (Detail) MWh in Millions	9 Months Ended
	Sep. 30, 2023 USD ($) MWh
Interest Rate Swap Current [Member]
Derivative [Line Items]
Interest rate | $	$ 0	[1]
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] | Electricity [Member]
Derivative [Line Items]
Fixed price | MWh	22

[1] Maturity is determined based on final settlement period.

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Derivative Financial Instruments (Fair Value of Derivatives) (Detail) - USD ($) $ in Millions		Sep. 30, 2023	Dec. 31, 2022
Derivative [Line Items]
Derivative Asset, Current	[1]	$ 18	$ 41
Derivative Asset, Current, Statement of Financial Position [Extensible Enumeration]		Other Assets, Current	Other Assets, Current
Derivative Asset, Noncurrent	[2]	$ 155	$ 211
Derivative Asset, Noncurrent, Statement of Financial Position [Extensible Enumeration]		Regulated Entity, Other Assets, Noncurrent	Regulated Entity, Other Assets, Noncurrent
Derivative Assets		$ 173	$ 252
Derivative Asset, Statement of Financial Position [Extensible Enumeration]		Assets	Assets
Derivative Liability, Noncurrent	[3]	$ 1	$ 2
Derivative Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration]		Liabilities, Noncurrent	Liabilities, Noncurrent
Derivative Liability		$ 1	$ 2
Derivative Liability, Statement of Financial Position [Extensible Enumeration]		Liabilities and Equity	Liabilities and Equity
Commodity Contract [Member]
Derivative [Line Items]
Derivative Asset, Current		$ 18	$ 41
Derivative Asset, Current, Statement of Financial Position [Extensible Enumeration]		Other Assets, Current	Other Assets, Current
Derivative Asset, Noncurrent		$ 153	$ 210
Derivative Asset, Noncurrent, Statement of Financial Position [Extensible Enumeration]		Regulated Entity, Other Assets, Noncurrent	Regulated Entity, Other Assets, Noncurrent
Interest Rate Contract [Member]
Derivative [Line Items]
Derivative Asset, Noncurrent		$ 2	$ 1
Derivative Asset, Noncurrent, Statement of Financial Position [Extensible Enumeration]		Regulated Entity, Other Assets, Noncurrent
Derivative Liability, Noncurrent		$ 1	$ 2
Derivative Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration]		Liabilities, Noncurrent	Liabilities, Noncurrent
Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative Asset, Current	[1]	$ 0	$ 0
Derivative Asset, Current, Statement of Financial Position [Extensible Enumeration]		Other Assets, Current	Other Assets, Current
Derivative Asset, Noncurrent	[2]	$ 0	$ 0
Derivative Asset, Noncurrent, Statement of Financial Position [Extensible Enumeration]		Regulated Entity, Other Assets, Noncurrent	Regulated Entity, Other Assets, Noncurrent
Derivative Assets		$ 0	$ 0
Derivative Asset, Statement of Financial Position [Extensible Enumeration]		Assets	Assets
Derivative Liability, Noncurrent	[3]	$ 0	$ 2
Derivative Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration]		Liabilities, Noncurrent	Liabilities, Noncurrent
Derivative Liability		$ 0	$ 2
Derivative Liability, Statement of Financial Position [Extensible Enumeration]		Liabilities and Equity	Liabilities and Equity
Designated as Hedging Instrument [Member] | Commodity Contract [Member]
Derivative [Line Items]
Derivative Asset, Current		$ 0	$ 0
Derivative Asset, Current, Statement of Financial Position [Extensible Enumeration]		Other Assets, Current	Other Assets, Current
Derivative Asset, Noncurrent		$ 0	$ 0
Derivative Asset, Noncurrent, Statement of Financial Position [Extensible Enumeration]		Regulated Entity, Other Assets, Noncurrent	Regulated Entity, Other Assets, Noncurrent
Designated as Hedging Instrument [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Derivative Asset, Noncurrent		$ 0	$ 0
Derivative Asset, Noncurrent, Statement of Financial Position [Extensible Enumeration]		Regulated Entity, Other Assets, Noncurrent
Derivative Liability, Noncurrent		$ 0	$ 2
Derivative Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration]		Liabilities, Noncurrent	Liabilities, Noncurrent
Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative Asset, Current	[1]	$ 18	$ 41
Derivative Asset, Current, Statement of Financial Position [Extensible Enumeration]		Other Assets, Current	Other Assets, Current
Derivative Asset, Noncurrent	[2]	$ 155	$ 211
Derivative Asset, Noncurrent, Statement of Financial Position [Extensible Enumeration]		Regulated Entity, Other Assets, Noncurrent	Regulated Entity, Other Assets, Noncurrent
Derivative Assets		$ 173	$ 252
Derivative Asset, Statement of Financial Position [Extensible Enumeration]		Assets	Assets
Derivative Liability, Noncurrent	[3]	$ 1	$ 0
Derivative Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration]		Liabilities, Noncurrent	Liabilities, Noncurrent
Derivative Liability		$ 1	$ 0
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		$ 18	$ 41
Derivative Asset, Current, Statement of Financial Position [Extensible Enumeration]		Other Assets, Current	Other Assets, Current
Derivative Asset, Noncurrent		$ 153	$ 210
Derivative Asset, Noncurrent, Statement of Financial Position [Extensible Enumeration]		Regulated Entity, Other Assets, Noncurrent	Regulated Entity, Other Assets, Noncurrent
Not Designated as Hedging Instrument [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Derivative Asset, Noncurrent		$ 2	$ 1
Derivative Asset, Noncurrent, Statement of Financial Position [Extensible Enumeration]		Regulated Entity, Other Assets, Noncurrent
Derivative Liability, Noncurrent		$ 1	$ 0
Derivative Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration]		Liabilities, Noncurrent	Liabilities, Noncurrent

[1] Current derivative assets are presented in other current assets in DESC’s Consolidated Balance Sheets.

[2] Noncurrent derivative assets are presented in other deferred debits and other assets in DESC’s Consolidated Balance Sheets.

[3] Noncurrent derivative liabilities are presented in other deferred credits and other liabilities in DESC’s Consolidated Balance Sheets.

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Derivative Financial Instruments (Derivatives in Cash Flow Hedging Relationships) (Detail) - Cash Flow Hedging [Member] - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Derivative [Line Items]
Increase (Decrease) in Derivatives Subject to Regulatory Treatment	[1]	$ 0	$ 2	$ 0	$ 10
Interest Rate Contract [Member]
Derivative [Line Items]
Increase (Decrease) in Derivatives Subject to Regulatory Treatment	[1]	$ 0	$ 2	$ 0	$ 10

[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.

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Derivative Financial Instruments (Derivatives Not Designated as Hedging Instruments) (Detail) - Not Designated as Hedging Instruments [Member] - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Derivative [Line Items]
Amount of Gain (Loss) Recognized in Income on Derivatives	[1]	$ 4	$ 47	$ 3	$ 64
Commodity Contract [Member]
Derivative [Line Items]
Amount of Gain (Loss) Recognized in Income on Derivatives	[1]	$ 4	$ 48	$ 4	$ 66
Derivative, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]		Utilities Operating Expense, Purchased Power	Utilities Operating Expense, Purchased Power	Utilities Operating Expense, Purchased Power	Utilities Operating Expense, Purchased Power
Interest Rate Contract [Member]
Derivative [Line Items]
Amount of Gain (Loss) Recognized in Income on Derivatives	[1]	$ 0	$ (1)	$ (1)	$ (2)
Derivative, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]		Interest Expense	Interest Expense	Interest Expense	Interest Expense

[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.

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Fair Value Measurements, Including Derivatives (Schedule of Quantitative Information About Level 3 Fair Value Measurements) (Details)	Sep. 30, 2023 USD ($)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total assets, fair value	$ 171,000,000
Electricity [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total assets, fair value	171,000,000
Minimum [Member] | Electricity [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total assets, fair value	25,000,000
Maximum [Member] | Electricity [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total assets, fair value	92,000,000
Weighted Average [Member] | Electricity [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total assets, fair value	$ 48,000,000	[1]

[1] Averages weighted by volume.

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Fair Value Measurements, Including Derivatives (Schedule of Assets and Liabilities Measured at Fair Value on Recurring Basis) (Details) - Fair value, recurring - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Assets
Total assets	$ 173	$ 252
Liabilities
Total liabilities	1	2
Commodity Contract [Member]
Assets
Total assets	171	251
Interest Rate Contract [Member]
Assets
Total assets	2	1
Liabilities
Total liabilities	1	2
Level 1
Assets
Total assets	0	0
Liabilities
Total liabilities	0	0
Level 1 | Commodity Contract [Member]
Assets
Total assets	0	0
Level 1 | Interest Rate Contract [Member]
Assets
Total assets	0	0
Liabilities
Total liabilities	0	0
Level 2
Assets
Total assets	2	1
Liabilities
Total liabilities	1	2
Level 2 | Commodity Contract [Member]
Assets
Total assets	0	0
Level 2 | Interest Rate Contract [Member]
Assets
Total assets	2	1
Liabilities
Total liabilities	1	2
Level 3
Assets
Total assets	171	251
Liabilities
Total liabilities	0	0
Level 3 | Commodity Contract [Member]
Assets
Total assets	171	251
Level 3 | Interest Rate Contract [Member]
Assets
Total assets	0	0
Liabilities
Total liabilities	$ 0	$ 0

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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		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Regulatory Assets
Beginning balance	$ 167	$ 295	$ 251	$ 148
Included in earnings:
Purchased power	5	48	5	66
Settlements	(5)	(48)	(5)	(66)
Ending balance	171	267	171	267
Other Regulatory Assets Liabilities
Included in earnings:
Included in regulatory assets/liabilities	$ 4	$ (28)	$ (80)	$ 119

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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		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Unrealized gains and losses	$ 0	$ 0	$ 0	$ 0

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Fair Value Measurements, Including Derivatives (Schedule of Carrying Values and Estimated Fair Values of Debt Instruments) (Detail) - USD ($) $ in Millions		Sep. 30, 2023	Dec. 31, 2022
Carrying Amount
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Long-term debt	[1]	$ 3,726	$ 3,725
Affiliated long-term debt	[2]	230	230
Estimated Fair Value
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Long-term debt	[1],[3]	3,438	3,614
Affiliated long-term debt	[2],[3]	$ 230	$ 230

[1] Carrying amount includes current portions presented in securities due within one year and amounts which represent the unamortized debt issuance costs and discount or premium.

[2] Carrying amount includes current portions presented in affiliated and related party payables.

[3] Fair value is estimated using market prices, where available, and interest rates currently available for issuance of debt with similar terms and remaining maturities. All fair value measurements are classified as Level 2. The carrying amount of debt issuances with short-term maturities and variable rates refinanced at current market rates is a reasonable estimate of their fair value.

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Employee Benefit Plans (Components of Net Periodic Benefit Cost (Credit) (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 2	$ 2	$ 6	$ 6
Interest cost	8	5	24	16
Expected return on assets	(8)	(12)	(25)	(37)
Amortization of actuarial losses	3	1	9	1
Net periodic benefit cost (credit)	5	(4)	14	(14)
Other Postretirement Benefits Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	0	1	1
Interest cost	2	1	6	4
Expected return on assets	0	0	0	0
Amortization of actuarial losses	(1)		(3)
Net periodic benefit cost (credit)	$ 1	$ 1	$ 4	$ 5

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Employee Benefit Plans (Narrative) (Detail) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2023
Retirement Benefits [Abstract]
Defined benefit plan, contributions by employer	$ 0	$ 0

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Commitments and Contingencies (Narrative) (Detail) shares in Millions		1 Months Ended														3 Months Ended	9 Months Ended
	Oct. 31, 2014 MGD Facility	Jul. 31, 2023 USD ($)	Jun. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)	Jun. 30, 2022 USD ($)	May 31, 2022 shares	Aug. 31, 2021 shares	Jun. 30, 2021 USD ($)	Dec. 31, 2020 USD ($)	Oct. 31, 2020	Nov. 30, 2019 gal	Jun. 30, 2018 USD ($)	Sep. 30, 2017 Petition	Apr. 30, 2017 Petition	Aug. 31, 2016 T	Mar. 31, 2023 USD ($)	Sep. 30, 2023 USD ($) Facility Indicator Product	Dec. 31, 2022 USD ($)
Loss Contingencies [Line Items]
Electric generating stations with water withdrawals under CWA | MGD	125
Electric generating stations with water withdrawals with heightened entrainment analysis under CWA | MGD	2
Number of DESC facilities subject to final regulations | Facility	5
Number of DESC hydroelectric facilities subject to regulations | Facility	5
Measurement of groundwater withdrawals | gal											3,000,000
Number of manufacturing gas plant decommissioned sites that contain residues of byproduct chemicals | Product																	4
Estimated environmental remediation activities at manufacturing gas plant sites																	$ 17,000,000
Environmental remediation costs recognized in regulatory assets																	$ 41,000,000
Number of facilities inactive subject to final rule | Facility																	3
Reserves for litigation and regulatory proceedings																	$ 3,000,000	$ 94,000,000
Insurance receivables																	26,000,000	68,000,000
Proportionate ownership share in project												100.00%
Proposed assessment amount from SCDOR audit												$ 410,000,000
Litigation settlement expense awarded									$ 165,000,000
Real estate transfer to satisfy obligation under settlement					$ 51,000,000
SCDOR
Loss Contingencies [Line Items]
Fair value of certain additional utility property transferred																		3,000,000
Fair value of certain remaining utility property transferred			$ 11,000,000
Fair value of certain non-utility property transferred				$ 28,000,000
Fair value of certain utility property transferred																$ 10,000,000
Gain from transferred utility property																	9,000,000
Gain from transferred utility property, after tax																	7,000,000
Gain from transferred remaining utility property																	11,000,000
Gain from transferred remaining utility property, after tax																	$ 8,000,000
Common Stock | Dominion Energy
Loss Contingencies [Line Items]
Litigation settlement through cash								$ 43,000,000
Shares issued on settlement | shares						0.9	0.6
Unfavorable Regulatory Action | CWA
Loss Contingencies [Line Items]
Number of mandatory facility specific factors. | Indicator																	5
Number of optional facility specific factors | Indicator																	6
Personal Injury or Wrongful Death Cases
Loss Contingencies [Line Items]
Reserves for litigation and regulatory proceedings																		$ 68,000,000
Maximum [Member] | SCDOR
Loss Contingencies [Line Items]
Cash payment		$ 1,000,000
Carbon Regulations [Member] | Minimum [Member]
Loss Contingencies [Line Items]
Significant emission rate per year CO2 equivalent | T															75,000
EPA
Loss Contingencies [Line Items]
Number of petition agreed for reconsideration | Petition													2
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
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 circumstances period										2021
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 circumstances period										2028

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Operating Segments (Narrative) (Details) - Operating Segments $ in Millions	9 Months Ended
	Sep. 30, 2023 USD ($)
Corporate and Other
Segment Reporting Information [Line Items]
After- tax net income	$ 23
Dominion Energy South Carolina, Inc. [Member]
Segment Reporting Information [Line Items]
After- tax net income	21
Benefit related to real estate transactions	31
Benefit related to real estate transactions, after tax	$ 23

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Operating Segments - Schedule of Segment Information (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Segment Reporting Information [Line Items]
External revenue	[1]	$ 848	$ 1,083	$ 2,311	$ 2,841
Comprehensive income (loss) available (attributable) to common shareholder		141	168	309	390
Dominion Energy South Carolina, Inc. [Member]
Segment Reporting Information [Line Items]
External revenue		848	1,083	2,311	2,841
Comprehensive income (loss) available (attributable) to common shareholder		137	169	286	392
Corporate and Other
Segment Reporting Information [Line Items]
External revenue		0	0	0	0
Comprehensive income (loss) available (attributable) to common shareholder		$ 4	$ (1)	$ 23	$ (2)

[1] See Note 12 for amounts attributable to affiliates.

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Affiliated and Related Party Transactions (Schedule of Affiliated Transactions - Income Statement) (Detail) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Related Party Transaction [Line Items]
Operating Revenues - Electric from sales to affiliate		$ 1	$ 1	$ 3	$ 3
Operating Revenues – Gas from sales to affiliate		1	1	1	1
Operating Expenses - Other taxes from affiliate		2	1	7	6
Solar Affiliates [Member]
Related Party Transaction [Line Items]
Purchases from affiliate		5	5	11	12
Related Party | DES
Related Party Transaction [Line Items]
Direct and allocated costs	[1]	$ 53	$ 52	$ 165	$ 158

[1] Includes capitalized expenditures of $15 million and $12 million for the three months ended September 30, 2023 and 2022, respectively and $44 million and $36 million for the nine months ended September 30, 2023 and 2022.

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Affiliated and Related Party Transactions (Schedule of Affiliated Transactions - Income Statement) (Parenthetical) (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
DES
Related Party Transaction [Line Items]
Capitalized expenditures	$ 15	$ 12	$ 44	$ 36

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Affiliated and Related Party Transactions (Schedule of Affiliated Transactions - Balance Sheet) (Detail) - USD ($) $ in Millions		Sep. 30, 2023	Jun. 30, 2023	Dec. 31, 2022
Related Party Transaction [Line Items]
Affiliated and related party payables and other		$ 135		$ 115
Derivative assets with affiliates	[1]		$ 33	51
Solar Affiliates [Member]
Related Party Transaction [Line Items]
Affiliated and related party payables and other			1	0
Dominion Energy | Related Party
Related Party Transaction [Line Items]
Affiliated and related party payables and other			2	1
DES | Related Party
Related Party Transaction [Line Items]
Affiliated and related party payables and other			18	22
SCANA Corporation | Related Party
Related Party Transaction [Line Items]
Affiliated and related party payables and other			7	7
Public Service Company Of North Carolina Incorporated | Related Party
Related Party Transaction [Line Items]
Affiliated and related party payables and other			$ 9	$ 12

[1] Includes amounts recorded in other current assets of $4 million and $8 million as of September 30, 2023 and December 31, 2022, respectively, and amounts recorded in other deferred debits and other assets of $29 million and $43 million as of September 30, 2023 and December 31, 2022, respectively.

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Affiliated and Related Party Transactions (Schedule of Affiliated Transactions - Balance Sheet) (Parenthetical) (Detail) - USD ($) $ in Millions		Sep. 30, 2023	Jun. 30, 2023	Dec. 31, 2022
Related Party Transaction [Line Items]
Derivative assets with affiliates	[1]		$ 33	$ 51
Other Current Assets [Member]
Related Party Transaction [Line Items]
Derivative assets with affiliates		$ 4		8
Other Deferred Debits and Other Assets [Member]
Related Party Transaction [Line Items]
Derivative assets with affiliates		$ 29		$ 43

[1] Includes amounts recorded in other current assets of $4 million and $8 million as of September 30, 2023 and December 31, 2022, respectively, and amounts recorded in other deferred debits and other assets of $29 million and $43 million as of September 30, 2023 and December 31, 2022, respectively.

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Other Income, Net (Components of Other Income, Net) (Detail) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Income Statement [Abstract]
Other income		$ 2	$ 2	$ 5	$ 5
Other expense		(4)	(1)	(11)
Gains on sales of assets	[1]		20	32	37
Allowance for equity funds used during construction			1		4
Other income, net		$ (2)	$ 22	$ 26	$ 46

[1] Includes amounts recognized in connection with the transfer of property to satisfy litigation. See Note 10 for additional information.

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Other Income, Net (Additional Information) (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Income Statement [Abstract]
Total cash consideration			$ 11	$ 16
Gain on sale of assets	$ 11	$ 16
Gain on sale of assets, after tax	$ 8	$ 12