Tennessee Valley Authority PARRS D 2028 (TVC) 10-K 13 Nov 24 2024 FY Annual report Financial data

DEI Document

DEI Document shares in Millions, $ in Millions	12 Months Ended
	Sep. 30, 2024 USD ($) shares
Document Information [Line Items]
Entity Registrant Name	TENNESSEE VALLEY AUTHORITY
Entity Central Index Key	0001376986
Entity Filer Category	Non-accelerated Filer
Document Type	10-K
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Common Stock, Shares Outstanding | shares	0
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Well-known Seasoned Issuer	No
Entity Public Float | $	$ 0
Document Transition Report	false
Entity File Number	000-52313
Entity Tax Identification Number	62-0474417
Entity Address, State or Province	TN
Entity Address, City or Town	Knoxville
Entity Address, Address Line One	400 W. Summit Hill Drive
Local Phone Number	632-2101
City Area Code	(865)
Entity Address, Postal Zip Code	37902 (Zip Code)
Entity Interactive Data Current	Yes
ICFR Auditor Attestation Flag	true
Entity Incorporation, State or Country Code	X1
Entity Current Reporting Status	Yes
Document Annual Report	true
Document Period End Date	Sep. 30, 2024
Entity Small Business	false
Entity Voluntary Filers	No
Current Fiscal Year End Date	--09-30
Document Financial Statement Error Correction [Flag]	false
Auditor Name	Ernst & Young LLP

Audit Information

Audit Information	12 Months Ended
	Sep. 30, 2024
Auditor [Line Items]
Auditor Name	Ernst & Young LLP
Auditor Location	Chattanooga, Tennessee
Auditor Firm ID	42

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Operating revenues
Regulated Operating Revenue	$ 12,128	$ 11,899	$ 12,371
Unregulated Operating Revenue	186	155	169
Revenue from sales of electricity	12,314	12,054	12,540
Operating expenses
Fuel	2,169	2,549	2,567
Purchased power	1,581	1,633	1,921
Operating and maintenance	3,641	3,372	2,986
Depreciation and amortization	2,138	2,213	2,054
Tax equivalents	557	593	601
Total operating expenses	10,086	10,360	10,129
Operating income	2,228	1,694	2,411
Other income (expense), net	71	61	7
Defined Benefit Plan, Other Cost (Credit)	98	199	258
Interest expense
Interest expense	1,066	1,056	1,052
Net income (loss)	$ 1,135	$ 500	$ 1,108

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Millions	Sep. 30, 2024	Sep. 30, 2023
Current assets
Cash and Cash Equivalents, at Carrying Value	$ 502	$ 501
Accounts receivable, net	1,801	1,745
Inventories, net	1,155	1,108
Regulatory assets	191	178
Other current assets	120	134
Total current assets	3,769	3,666
Property, Plant and Equipment, Gross	70,989	68,199
Property, plant, and equipment
Less accumulated depreciation	(38,793)	(35,871)
Net completed plant	32,196	32,328
Construction in progress	4,879	3,238
Nuclear fuel	1,261	1,344
Finance Lease, Right-of-Use-Asset, after Accumulated Amortization	729	572
Total property, plant, and equipment, net	39,065	37,482
Long-term Investments	4,968	4,123
Regulatory and other long-term assets
Regulatory assets	9,408	5,566
Operating Lease, Right-of-Use Asset	149	177
Other long-term assets	344	330
Investments and Other Noncurrent Assets	9,901	6,073
Total assets	57,703	51,344
Current liabilities
Accounts payable and accrued liabilities	2,910	2,618
Accrued interest	280	272
Asset Retirement Obligation, Current	283	272
Regulatory liabilities	174	222
Short-term debt, net of discounts	1,167	432
Total Current maturities of power bonds issued at par	1,022	1,022
Current maturities of long-term debt of variable interest entities issued at par	37	35
Total current liabilities	5,873	4,873
Other liabilities
Post-retirement and post-employment benefit obligations	2,887	2,527
Asset retirement obligations	10,523	7,217
Finance Lease, Liability, Noncurrent	700	576
Other long-term liabilities	1,712	1,211
Non-current regulatory liabilities	83	107
Noncurrent Liabilities Other than Long-Term Debt	15,905	11,638
Long-term debt, net
Long-term power bonds, net	17,867	17,844
Long-term debt of variable interest entities, net	897	933
Total long-term debt, net	18,764	18,777
Total liabilities	40,542	35,288
Proprietary capital
Power program appropriation investment	258	258
Power program retained earnings	16,437	15,302
Total power program proprietary capital	16,695	15,560
Nonpower programs appropriation investment, net	518	525
Accumulated other comprehensive income (loss)	(52)	(29)
Total proprietary capital	17,161	16,056
Liabilities and Equity	$ 57,703	$ 51,344

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	$ 523	$ 521	$ 520
Cash flows from operating activities
Net income (loss)	1,135	500	1,108
Adjustments to reconcile net income (loss) to net cash provided by operating activities
Depreciation and amortization (including amortization of debt issuance costs and premiums/discounts)	2,160	2,235	2,076
Amortization of nuclear fuel cost	364	371	347
Non-cash retirement benefit expense	138	241	328
Reg Asset Amortization	(71)
Regulatory asset amount expensed		31	70
Changes in current assets and liabilities
Accounts receivable, net	(16)	301	(412)
Inventories and other current assets, net	(70)	(83)	(163)
Accounts payable and accrued liabilities	44	(1)	282
Accrued interest	8	(1)	(7)
Pension contributions	(304)	(306)	(308)
Asset Retirement Obligation, Cash Paid to Settle	(283)	(327)	(291)
Other, net	(102)	(89)	(82)
Net cash provided by operating activities	3,003	2,872	2,948
Cash flows from investing activities
Construction expenditures	(3,281)	(2,526)	(2,361)
Nuclear fuel expenditures	(294)	(273)	(283)
Acquisition of leasehold interests in combustion turbine assets	0	155	0
Purchases of investments	(52)	(51)	(51)
Payments to Acquire Loans Receivable	4	7	9
Loans and other receivables
Repayments	6	8	15
Other, net	34	10	26
Net cash used in investing activities	(3,591)	(2,994)	(2,663)
Long-term debt
Issues of power bonds	991	992	484
Redemptions and repurchases of power bonds	(1,022)	(29)	(1,028)
Payments on debt of variable interest entities	(35)	(39)	(43)
Short-term debt issues (redemptions), net	734	(740)	392
Finance Lease, Principal Payments	76	56	85
Financing costs, net	(5)	(4)	(3)
Other, net	3	(1)	0
Net cash (used in) provided by financing activities	590	123	(283)
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Excluding Exchange Rate Effect		$ 1	$ 2
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect, Total	$ 2

CONSOLIDATED STATEMENTS OF CHAN

CONSOLIDATED STATEMENTS OF CHANGES IN PROPRIETARY CAPITAL - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Net income (loss)	$ 1,135	$ 500	$ 1,108
Total other comprehensive income (loss)	(23)	57	(64)
Return on power program appropriation investment	(7)	(6)	(4)
Appropriation-investment power program	258	258
Retained Earnings Power Program	16,437	15,302
Appropriation investment nonpower programs, net	518	525
Accumulated other comprehensive income (loss)	(52)	(29)
Proprietary Capital	17,161	16,056	15,505	$ 14,465
Power Program Appropriation Investment
Net income (loss)	0	0	0
Total other comprehensive income (loss)	0	0	0
Return on power program appropriation investment	0	0	0
Appropriation-investment power program	258	258	258	258
Power Program Retained Earnings
Net income (loss)	1,142	508	1,115
Total other comprehensive income (loss)	0	0	0
Return on power program appropriation investment	(7)	(6)	4
Retained Earnings Power Program	16,437	15,302	14,800	13,689
Nonpower Programs Appropriation Investment, Net
Net income (loss)	(7)	(8)	(7)
Total other comprehensive income (loss)	0	0	0
Return on power program appropriation investment	0	0	0
Appropriation investment nonpower programs, net	518	525	533	540
Accumulated Other Comprehensive Income (Loss) Net Gains (Losses) on Cash Flow Hedges
Net income (loss)	0	0	0
Total other comprehensive income (loss)	(23)	57	(64)
Return on power program appropriation investment	0	0	0
Accumulated other comprehensive income (loss)	$ (52)	$ (29)	$ (86)	$ (22)

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) Statement - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 1,135	$ 500	$ 1,108
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), before Reclassification, after Tax	25	99	(157)
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, after Tax	(48)	(42)	93
Total other comprehensive income (loss)	(23)	57	(64)
Total comprehensive income (loss)	$ 1,112	$ 557	$ 1,044

Supplemental Cash Flow Informat

Supplemental Cash Flow Information	12 Months Ended
	Sep. 30, 2024
Supplemental Cash Flow Information [Abstract]
Supplemental Cash Flow Information	Interest paid was $1.1 billion for each of 2024, 2023, and 2022. These amounts differ from interest expense in certain years due to the timing of payments. There was no interest capitalized in 2024, 2023, or 2022. Construction in progress and nuclear fuel expenditures included in Accounts payable and accrued liabilities at September 30, 2024, 2023, and 2022 were $898 million, $559 million, and $510 million, respectively, and are excluded from the Consolidated Statements of Cash Flows for the years ended September 30, 2024, 2023, and 2022 as non-cash investing activities. ARO project accruals included in Accounts payable and accrued liabilities at September 30, 2024, 2023, and 2022 were $45 million, $71 million, and $119 million, respectively, and are excluded from the Consolidated Statements of Cash Flows for the years ended September 30, 2024, 2023, and 2022 as non-cash operating activities. Excluded from the Consolidated Statements of Cash Flows for the year ended September 30, 2024, were non-cash investing and financing activities of $230 million primarily related to two finance leases. There was a $56 million lease asset and lease liability recorded as a result of a new finance lease entered into in May 2024. In addition, there was a $163 million lease liability and a $179 million lease asset recorded as a remeasurement of an existing lease due to change in lease term. There are no material finance leases that were entered into during the years ended September 30, 2023, and 2022. See Note 8 — Leases for further information regarding TVA's finance leases. Cash flows from swap contracts that are accounted for as hedges are classified in the same category as the item being hedged or on a basis consistent with the nature of the instrument.

Supplemental Cash Flow Inform_2

Supplemental Cash Flow Information - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Supplemental Cash Flow Information
Interest Paid, Excluding Capitalized Interest, Operating Activities	$ 1,100	$ 1,100	$ 1,100
ARO project accruals included in AP	45	71	119
Capital Expenditures Incurred but Not yet Paid	898	559	510
Lease assets obtained in exchange for lease obligations - finance	$ 230	$ 3	$ 0

Summary of Significant Accounti

Summary of Significant Accounting Policies [Text Block]	12 Months Ended
	Sep. 30, 2024
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	1. Summary of Significant Accounting Policies General The Tennessee Valley Authority ("TVA") is a corporate agency and instrumentality of the United States ("U.S.") that was created in 1933 by federal legislation in response to a proposal by President Franklin D. Roosevelt. TVA was created to, among other things, improve navigation on the Tennessee River, reduce the damage from destructive flood waters within the Tennessee River system and downstream on the lower Ohio and Mississippi Rivers, further the economic development of TVA's service area in the southeastern U.S., and sell the electricity generated at the facilities TVA operates. Today, TVA operates the nation's largest public power system and supplies power in most of Tennessee, northern Alabama, northeastern Mississippi, and southwestern Kentucky and in portions of northern Georgia, western North Carolina, and southwestern Virginia to a population of approximately 10 million people. TVA also manages the Tennessee River, its tributaries, and certain shorelines to provide, among other things, year-round navigation, flood damage reduction, and affordable and reliable electricity. Consistent with these primary purposes, TVA also manages the river system and public lands to provide recreational opportunities, adequate water supply, improved water quality, cultural and natural resource protection, and economic development. TVA performs these management duties in cooperation with other federal and state agencies that have jurisdiction and authority over certain aspects of the river system. In addition, the TVA Board of Directors ("TVA Board") has established two councils — the Regional Resource Stewardship Council and the Regional Energy Resource Council — to advise TVA on its stewardship activities in the Tennessee Valley and its energy resource activities. The power program has historically been separate and distinct from the stewardship programs. It is required to be self-supporting from power revenues and proceeds from power financings, such as proceeds from the issuance of bonds, notes, or other evidences of indebtedness (collectively, "Bonds"). Although TVA does not currently receive Congressional appropriations, it is required to make annual payments to the United States Department of the Treasury ("U.S. Treasury") as a return on the government's appropriation investment in TVA's power facilities (the "Power Program Appropriation Investment"). In the 1998 Energy and Water Development Appropriations Act, Congress directed TVA to fund essential stewardship activities related to its management of the Tennessee River system and nonpower or stewardship properties with power revenues in the event that there were insufficient appropriations or other available funds to pay for such activities in any fiscal year. Congress has not provided any appropriations to TVA to fund such activities since 1999. Consequently, during 2000, TVA began paying for essential stewardship activities primarily with power revenues, with the remainder funded with user fees and other forms of revenues derived in connection with those activities. The activities related to stewardship properties do not meet the criteria of an operating segment under accounting principles generally accepted in the United States of America ("GAAP"). Accordingly, these assets and properties are included as part of the power program, TVA's only operating segment. Power rates are established by the TVA Board as authorized by the Tennessee Valley Authority Act of 1933, as amended ("TVA Act"). The TVA Act requires TVA to charge rates for power that will produce gross revenues sufficient to provide funds for operation, maintenance, and administration of its power system; payments to states and counties in lieu of taxes ("tax equivalents"); debt service on outstanding indebtedness; payments to the U.S. Treasury in repayment of and as a return on the Power Program Appropriation Investment; and such additional margin as the TVA Board may consider desirable for investment in power system assets, retirement of outstanding Bonds in advance of maturity, additional reduction of the Power Program Appropriation Investment, and other purposes connected with TVA's power business. TVA fulfilled its requirement to repay $1.0 billion of the Power Program Appropriation Investment with the 2014 payment; therefore, this repayment obligation is no longer a component of rate setting. In setting TVA's rates, the TVA Board is charged by the TVA Act to have due regard for the primary objectives of the TVA Act, including the objective that power shall be sold at rates as low as are feasible. Rates set by the TVA Board are not subject to review or approval by any state or other federal regulatory body. Fiscal Year TVA's fiscal year ends September 30. Years (2024, 2023, etc.) refer to TVA's fiscal years unless they are preceded by "CY," in which case the references are to calendar years. Cost-Based Regulation Since the TVA Board is authorized by the TVA Act to set rates for power sold to its customers, TVA is self-regulated. Additionally, TVA's regulated rates are designed to recover its costs. Based on current projections, TVA believes that rates, set at levels that will recover TVA's costs, can be charged and collected. As a result of these factors, TVA records certain assets and liabilities that result from the regulated ratemaking process that would not be recorded under GAAP for non-regulated entities. Regulatory assets generally represent incurred costs that have been deferred because such costs are probable of future recovery in customer rates. Regulatory liabilities generally represent obligations to make refunds to customers for previous collections for costs that are not likely to be incurred or deferral of gains that will be credited to customers in future periods. TVA assesses whether the regulatory assets are probable of future recovery by considering factors such as applicable regulatory changes, potential legislation, and changes in technology. Based on these assessments, TVA believes the existing regulatory assets are probable of recovery. This determination reflects the current regulatory and political environment and is subject to change in the future. If future recovery of regulatory assets ceases to be probable, or TVA is no longer considered to be a regulated entity, then costs would be required to be written off. All regulatory asset write offs would be required to be recognized in earnings in the period in which future recovery ceases to be probable or in which TVA is no longer considered to be a regulated entity. Basis of Presentation The accompanying consolidated financial statements, which have been prepared in accordance with GAAP, include the accounts of TVA and variable interest entities ("VIEs") of which TVA is the primary beneficiary. See Note 11 — Variable Interest Entities . Intercompany balances and transactions have been eliminated in consolidation. Use of Estimates The preparation of financial statements requires TVA to estimate the effects of various matters that are inherently uncertain as of the date of the consolidated financial statements. Although the consolidated financial statements are prepared in conformity with GAAP, TVA is required to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities, and the amounts of revenues and expenses reported during the reporting period. Each of these estimates varies in regard to the level of judgment involved and its potential impact on TVA's financial results. Estimates are considered critical either when a different estimate could have reasonably been used, or where changes in the estimate are reasonably likely to occur from period to period, and such use or change would materially impact TVA's financial condition, results of operations, or cash flows. Cash, Cash Equivalents, and Restricted Cash Cash includes cash on hand, non-interest bearing cash, and deposit accounts. All highly liquid investments with original maturities of three months or less are considered cash equivalents. Cash and cash equivalents that are restricted, as to withdrawal or use under the terms of certain contractual agreements, are recorded in Other long-term assets on the Consolidated Balance Sheets. Restricted cash and cash equivalents include cash held in trusts that are currently restricted for TVA economic development loans and for certain TVA environmental programs in accordance with agreements related to compliance with certain environmental regulations. See Note 22 — Commitments and Contingencies — Legal Proceedings — Environmental Agreements . The following table provides a reconciliation of cash, cash equivalents, and restricted cash reported on the Consolidated Balance Sheets and Consolidated Statements of Cash Flows: Cash, Cash Equivalents, and Restricted Cash At September 30 (in millions) 2024 2023 Cash and cash equivalents $ 502 $ 501 Restricted cash and cash equivalents included in Other long-term assets 21 20 Total cash, cash equivalents, and restricted cash $ 523 $ 521 Allowance for Uncollectible Accounts TVA recognizes an allowance that reflects the current estimate for credit losses expected to be incurred over the life of the financial assets based on historical experience, current conditions, and reasonable and supportable forecasts that affect the collectability of the reported amounts. The appropriateness of the allowance is evaluated at the end of each reporting period. To determine the allowance for trade receivables, TVA considers historical experience and other currently available information, including events such as customer bankruptcy and/or a customer failing to fulfill payment arrangements by the due date. TVA's corporate credit department also performs an assessment of the financial condition of customers and the credit quality of the receivables. In addition, TVA reviews other reasonable and supportable forecasts to determine if the allowance for uncollectible amounts should be further adjusted in accordance with the accounting guidance for Current Expected Credit Losses. To determine the allowance for loans receivables, TVA aggregates loans into the appropriate pools based on the existence of similar risk characteristics such as collateral types and internal assessed credit risks. In situations where a loan exhibits unique risk characteristics and is no longer expected to experience similar risks to the rest of its pool, the loan will be evaluated separately. TVA derives an annual loss rate based on historical loss and then adjusts the rate to reflect TVA's consideration of available information on current conditions and reasonable and supportable future forecasts. This information may include economic and business conditions, default trends, and other internal and external factors. For periods beyond the reasonable and supportable forecast period, TVA uses the current calculated long-term average historical loss rate for the remaining life of the loan portfolio. The allowance for uncollectible accounts was less than $1 million at both September 30, 2024 and 2023, for trade accounts receivable. Additionally, loans receivable of $105 million and $104 million at September 30, 2024 and 2023, respectively, are included in Accounts receivable, net and Other long-term assets for the current and long-term portions, respectively. Loans receivables are reported net of allowances for uncollectible accounts of $2 million a n d $3 million at September 30, 2024 and 2023, respectively. Revenues TVA recognizes revenue from contracts with customers to depict the transfer of goods or services to customers in an amount to which the entity expects to be entitled in exchange for those goods or services. For the generation and transmission of electricity, this is generally at the time the power is delivered to a metered customer delivery point for the customer's consumption or distribution. As a result, revenues from power sales are recorded as electricity is delivered to customers. In addition to power sales invoiced and recorded during the month, TVA accrues estimated unbilled revenues for power sales provided to five customers whose billing date occurs prior to the end of the month. Exchange power sales are presented in the accompanying Consolidated Statements of Operations as a component of sales of electricity. Exchange power sales are sales of excess power after meeting TVA native load and directly served requirements. Native load refers to the customers on whose behalf a company, by statute, franchise, regulatory requirement, or contract, has undertaken an obligation to serve. TVA engages in other arrangements in addition to power sales. Certain other revenue from activities related to TVA's overall mission is recorded in Other revenue. Revenues that are not related to the overall mission are recorded in Other income, net. Inventories Certain Fuel, Materials, and Supplies . Materials and supplies inventories are valued using an average unit cost method. A new average cost is computed after each inventory purchase transaction, and inventory issuances are priced at the latest moving weighted average unit cost. Coal, fuel oil, and natural gas inventories are valued using an average cost method. A new weighted average cost is computed monthly, and monthly issues are priced accordingly. Renewable Energy Certificates. TVA accounts for Renewable Energy Certificates ("RECs") using the specific identification cost method. RECs that are acquired through power purchases are recorded as inventory and charged to purchased power expense when the RECs are subsequently used or sold. TVA assigns a value to the RECs at the inception of the power purchase arrangement using a relative standalone selling price approach. RECs created through TVA-owned asset generation are recorded at zero cost. Emission Allowances . TVA accounts for emission allowances using the specific identification cost method. Allowances that are acquired through third party purchases are recorded as inventory at cost and charged to operating expense based on tons emitted during the respective compliance periods. Allowance for Inventory Obsolescence . TVA reviews materials and supplies inventories by category and usage on a periodic basis. Each category is assigned a probability of becoming obsolete based on the type of material and historical usage data. TVA has a fleet-wide inventory management policy for each generation type. Based on the estimated value of the inventory, TVA adjusts its allowance for inventory obsolescence. Pre-Commercial Plant Operations As part of the process of completing the construction of a generating unit, the electricity produced is used to serve the demands of the electric system. TVA estimates revenues earned during pre-commercial operations at the fair value of the energy delivered based on TVA's hourly incremental dispatch cost. Pre-commercial plant operations began on Paradise CT Units 5-7 in the first quarter of 2024, and the units became operational on December 29, 2023. Estimated revenue of $3 million related to this project was capitalized to offset project costs for the year ended September 30, 2024. TVA also capitalized related fuel costs for this project of $3 million for the year ended September 30, 2024, all of which was recognized in the three months ended December 31, 2023. Property, Plant, and Equipment, and Depreciation Property, Plant, and Equipment. Additions to plant are recorded at cost, which includes direct and indirect costs. The cost of current repairs and minor replacements is charged to operating expense. When property, plant, and equipment is retired, accumulated depreciation is charged for the original cost of the assets. Gains or losses are only recognized upon the sale of land or an entire operating unit. TVA capitalizes certain costs incurred in connection with developing or obtaining internal-use software. Capitalized software costs are included in Property, plant, and equipment on the Consolidated Balance Sheets and are generally amortized over seven years. Nuclear Fuel. Nuclear fuel, which is included in Property, plant, and equipment, is valued using the average cost method for raw materials and the specific identification method for nuclear fuel in a reactor. Amortization of nuclear fuel in a reactor is calculated on a units-of-production basis and is included in fuel expense. TVA, the U.S. Department of Energy ("DOE"), and certain nuclear fuel contractors have entered into agreements, referred to as the Down-blend Offering for Tritium ("DBOT"), that provide for the production, processing, and storage of low-enriched uranium that is to be made using e fabricated into fuel for use in a nuclear power plant. Production of the low-enriched uranium began in 2019 and is contracted to continue through September 2027. Contract activity after that date will consist of storage and flag management. Flag management ensures that the uranium is unencumbered by policy restrictions, so that it can be used in connection with the production of tritium. Under the terms of the interagency agreement between the DOE and TVA, the DOE will reimburse TVA for a portion of the costs of converting the highly enriched uranium to low-enriched uranium. Since 2019, TVA has received $284 million in reimbursements from the DOE, which is recorded as a reduction in nuclear fuel inventory costs. At September 30, 2024, TVA recorded $13 million in Accounts receivable, net related to this agreement. Depreciation. TVA accounts for depreciation of its properties using the composite depreciation convention of accounting. Under the composite method, assets with similar economic characteristics are grouped and depreciated as one asset. Depreciation is generally computed on a straight-line basis over the estimated service lives of the various classes of assets. The estimation of asset useful lives requires management judgment, supported by external depreciation studies of historical asset retirement experience. Depreciation rates are determined based on external depreciation studies that are updated approximately every five years, with the latest study implemented in 2022. Depreciation expense for the years ended September 30, 2024, 2023, and 2022 was $1.8 billion, $1.9 billion, and $1.8 billion, respectively. Depreciation expense expressed as a percentage of the average annual depreciable completed plant was 2.92 percent for 2024, 3.14 percent for 2023, and 2.98 percent for 2022. Average depreciation rates by asset class are as follows: Property, Plant, and Equipment Depreciation Rates At September 30 2024 2023 2022 Asset Class Nuclear 2.71 2.73 2.72 Coal-fired (1) 4.13 4.98 4.27 Hydroelectric 1.83 1.82 1.85 Gas and oil-fired 3.31 3.17 3.38 Transmission 1.52 1.52 1.51 Other 4.98 4.43 3.64 Note (1) The rates include the acceleration of depreciation related to retiring certain coal-fired units and potentially retiring the remainder of the coal-fired fleet by 2035. See Note 7 — Plant Closures . Reacquired Rights . TVA previously entered into leasing transactions to obtain third-party financing for 24 peaking CTs as well as certain qualified technological equipment and software (“QTE”). All of the lease proceeds were accounted for as financing obligations due to TVA’s continuing involvement with the combustion turbine facilities and the QTE during the leaseback term. These financial obligations were paid off, and TVA acquired the residual leasehold interests for all of this equipment and recorded the cash consideration as reacquired rights, which is an intangible asset included in property, plant, and equipment on the Consolidated Balance Sheet. As of September 30, 2024 and 2023, property, plant, and equipment includes intangible reacquired rights, net of amortization, of $312 million and $324 million, respectively. Reacquired rights are amortized over the estimated useful lives of the underlying CTs which range from 30 to 35 years. Amortization expense was $11 million, $10 million, and $6 million for the years ended September 30, 2024, 2023, and 2022, respectively, and accumulated amortization at September 30, 2024 and 2023 totaled $63 million and $52 million, respectively. At September 30, 2024, the estimated aggregate amortization expense for each of the next five years and thereafter is shown below: 2025 2026 2027 2028 2029 Thereafter Reacquired Rights $ 12 $ 11 $ 12 $ 11 $ 11 $ 255 Impairment of Assets. TVA evaluates long-lived assets for impairment when events or changes in circumstances indicate that the carrying value of such assets may not be recoverable. For long-lived assets, TVA bases its evaluation on impairment indicators such as the nature of the assets, the future economic benefit of the assets, any historical or future profitability measurements, regulatory approval and ability to set rates at levels that allow for recoverability of the assets, and other external market conditions or factors that may be present. If such impairment indicators are present or other factors exist that indicate that the carrying amount of an asset may not be recoverable, TVA determines whether an impairment has occurred based on an estimate of undiscounted cash flows attributable to the asset as compared with the carrying value of the asset. If an impairment has occurred, the amount of the impairment recognized is measured as the excess of the asset's carrying value over its fair value. Additionally, TVA regularly evaluates construction projects. If the project is canceled or deemed to have no future economic benefit, the project is written off as an asset impairment or, upon TVA Board approval, reclassified as a regulatory asset and amortized over the Board-approved period. See Note 7 — Plant Closures . Leases TVA recognizes a lease asset and lease liability for leases with terms of greater than 12 months. Lease assets represent TVA's right to use an underlying asset for the lease term, and lease liabilities represent TVA's obligation to make lease payments arising from the lease, both of which are recognized based on the present value of the future minimum lease payments over the lease term at the commencement date. TVA has certain lease agreements that include variable lease payments that are based on energy production levels. These variable lease payments are not included in the measurement of the lease assets or lease liabilities but are recognized in the period in which the expenses are incurred. While not specifically structured as leases, certain power purchase agreements ("PPAs") are deemed to contain a lease of the underlying generating units when the terms convey the right to control the use of the assets. Amounts recorded for these leases are generally based on the amount of the scheduled capacity payments due over the remaining terms of the PPAs, the terms of which vary. The total lease obligations included in Accounts payable and accrued liabilities, Other long-term liabilities, and Finance lease liabilities related to these agreements were $550 million and $121 million for finance and operating leases, respectively, at September 30, 2024. The total lease obligations included in Accounts payable and accrued liabilities, Other long-term liabilities, and Finance lease liabilities related to these agreements were $390 million and $135 million for finance and operating leases, respectively, at September 30, 2023. TVA has agreements with lease and non-lease components and has elected to separate lease and non-lease components. Consideration is allocated to lease and non-lease components generally based on relative standalone price basis. Variable lease costs included in the agreements are allocated based on the determination of lease and non-lease components. TVA has lease agreements which include options for renewal and early termination. The intent to renew a lease varies depending on the lease type and asset. Renewal options that are reasonably certain to be exercised are included in the lease measurements. The decision to terminate a lease early is dependent on various economic factors. No termination options have been included in TVA's lease measurements. Leases with an initial term of 12 months or less, which do not include an option to extend the initial term of the lease to greater than 12 months that TVA is reasonably certain to exercise, are not recorded on the Consolidated Balance Sheets at September 30, 2024. Operating leases are recognized on a straight-line basis over the term of the lease agreement. Rent expense associated with short-term leases and variable leases is recorded in Operating and maintenance expense, Fuel expense, or Purchased power expense on the Consolidated Statements of Operations. Expenses associated with finance leases result in the separate presentation of interest expense on the lease liability and amortization expense of the related lease asset on the Consolidated Statements of Operations. Decommissioning Costs TVA recognizes legal obligations associated with the future retirement of certain tangible long-lived assets. These obligations relate to fossil fuel-fired generating plants, nuclear generating plants, hydroelectric generating plants/dams, transmission structures, and other property-related assets. Activities involved with retiring these assets could include decontamination and demolition of structures, removal and disposal of wastes, and site restoration. Revisions to the forecasted costs of decommissioning activities are made whenever factors indicate that the timing or amounts of estimated cash flows have changed materially. Studies are updated for both nuclear and non-nuclear decommissioning costs at least every five years. Any accretion or depreciation expense related to these liabilities and assets is charged to a regulatory asset. See Note 10 — Regulatory Assets and Liabilities — Nuclear Decommissioning Costs and Non-Nuclear Decommissioning Costs and Note 13 — Asset Retirement Obligations. Investment Funds Investment funds consist primarily of trust funds designated to fund decommissioning requirements (see Note 22 — Commitments and Contingencies — Contingencies — Decommissioning Costs ), the Supplemental Executive Retirement Plan ("SERP") (see Note 20 — Benefit Plans — Overview of Plans and Benefits — Supplemental Executive Retirement Plan ), the Deferred Compensation Plan ("DCP"), and the Restoration Plan ("RP"). The Nuclear Decommissioning Trust ("NDT") holds funds primarily for the ultimate decommissioning of TVA's nuclear power plants. The Asset Retirement Trust ("ART") holds funds primarily for the costs related to the future closure and retirement of TVA's other long-lived assets. The NDT, ART, SERP, DCP, and RP funds are invested in portfolios of securities generally designed to achieve a return in line with overall equity and debt market performance. The NDT, ART, SERP, DCP, and RP funds are all classified as trading. Research and Development Costs Research and development costs are expensed when incurred. TVA's research programs include those related to power delivery technologies, emerging technologies (clean energy, renewables, distributed resources, and energy efficiency), technologies related to generation (fossil fuel, nuclear, and hydroelectric), and environmental technologies. Tax Equivalents TVA is not subject to federal income taxation. In addition, neither TVA nor its property, franchises, or income is subject to taxation by states or their subdivisions. The TVA Act requires TVA to make payments to states and counties in which TVA conducts its power operations and in which TVA has acquired power properties previously subject to state and local taxation. The total amount of these payments is five percent of gross revenues from sales of power during the preceding year, excluding sales or deliveries to other federal agencies and off-system sales with other utilities, with a provision for minimum payments under certain circumstances. TVA calculates tax equivalent expense by subtracting the prior year fuel cost-related tax equivalent regulatory asset or liability from the payments made to the states and counties during the current year and adding back the current year fuel cost-related tax equivalent regulatory asset or liability. Fuel cost-related tax equivalent expense is recognized in the same accounting period in which the fuel cost-related revenue is recognized. Maintenance Costs

Impact of New Accounting Standa

Impact of New Accounting Standards and Interpretations	12 Months Ended
	Sep. 30, 2024
Accounting Changes and Error Corrections [Abstract]
Accounting Standards Update and Change in Accounting Principle [Text Block]	Impact of New Accounting Standards and Interpretations The following are accounting standard updates issued by the Financial Accounting Standards Board that TVA adopted during 2024: Accounting for Contract Assets and Contract Liabilities from Contracts with Customers Description This guidance requires an entity (acquirer) to recognize and measure contract assets and contract liabilities acquired in a business combination in accordance with revenue with customers. It is expected that an acquirer will generally recognize and measure acquired contract assets and contract liabilities in a manner consistent with how the acquiree recognized and measured contract assets and contract liabilities in the acquiree’s financial statements. The entity should apply the standard prospectively to business combinations occurring on or after the effective date of the standard. Effective Date for TVA TVA adopted the standard on October 1, 2023, on a prospective basis. Effect on the Financial Statements or Other Significant Matters Adoption of this standard did not have a material impact on TVA's financial condition, results of operations, or cash flows. Troubled Debt Restructurings and Vintage Disclosures Description This guidance eliminates the recognition and measurement guidance on troubled debt restructuring for creditors that have adopted Financial Instruments-Credit Losses and requires enhanced disclosures about loan modifications for borrowers experiencing financial difficulty. Additionally, the guidance requires public business entities to present current-period gross write-offs by year of origination in their vintage disclosures. The entity should apply the standard prospectively except for the transition method related to the recognition and measurement of troubled debt restructuring. For the transition method, an entity has the option to apply a modified retrospective transition method, resulting in a cumulative-effect adjustment to retained earnings in the period of adoption. Effective Date for TVA TVA adopted the standard on October 1, 2023, on a prospective basis. Effect on the Financial Statements or Other Significant Matters Adoption of this standard did not have a material impact on TVA's financial condition, results of operations, or cash flows. The following accounting standards or rules have been issued but as of September 30, 2024, were not effective and had not been adopted by TVA: Improvements to Reportable Segment Disclosures Description This guidance improves reportable segment disclosure requirements, primarily through enhanced disclosures about significant segment expenses. The amendment requires a public entity to disclose, on an annual and interim basis, significant segment expenses that are regularly provided to the chief operating decision maker and included within each reported measure of segment profit and loss. It also requires a public entity that has a single reportable segment to provide all of the disclosures required by the amendment and all existing segment disclosures. The amendment is effective for public entities for fiscal years beginning after December 15, 2023, and interim periods in fiscal years beginning after December 15, 2024. Upon adoption, a public entity should apply the amendments retrospectively to all prior periods presented in the financial statements. Effective Date for TVA Fiscal years beginning October 1, 2024 and interim periods beginning October 1, 2025. Effect on the Financial Statements or Other Significant Matters The adoption of this standard will result in TVA including the additional required disclosures and will have no impact on TVA's financial condition, results of operations, or cash flows. Enhancement and Standardization of Climate-Related Disclosures for Investors Description In March 2024, the SEC adopted its climate-related final rule (SEC Release No. 34-99678, The Enhancement and Standardization of Climate-Related Disclosures for Investors), and in April 2024, the SEC voluntarily stayed the new rule as a result of pending legal challenges. The new rule, if implemented as adopted, will require registrants to provide certain climate-related information in their annual reports and registration statements and will also require the dollar impact of severe weather events and other natural conditions, as well as amounts related to carbon offsets and renewable energy credits or certificates, to be disclosed in the audited financial statements in certain circumstances. The disclosure requirements are currently expected to begin phasing in for fiscal years beginning on or after January 1, 2027 for non-accelerated filers. Effective Date for TVA Fiscal year beginning October 1, 2027. Effect on the Financial Statements or Other Significant Matters TVA is currently evaluating the impact of the rule on its disclosures.

Accounts Receivable, Net

Accounts Receivable, Net	12 Months Ended
	Sep. 30, 2024
Accounts Receivable, after Allowance for Credit Loss [Abstract]
Accounts Receivable, Net	3. Accounts Receivable, Net Accounts receivable primarily consist of amounts due from customers for power sales. The table below summarizes the types and amounts of TVA's accounts receivable: Accounts Receivable, Net At September 30 (in millions) 2024 2023 Power receivables $ 1,683 $ 1,627 Other receivables 118 118 Accounts receivable, net (1) $ 1,801 $ 1,745 Note (1) Allowance for uncollectible accounts was less than $1 million at both September 30, 2024 and 2023, and therefore is not represented in the table above.

Inventories, Net

Inventories, Net	12 Months Ended
	Sep. 30, 2024
Inventory, Net [Abstract]
Inventories, Net	4. Inventories, Net The table below summarizes the types and amounts of TVA's inventories: Inventories, Net At September 30 (in millions) 2024 2023 Materials and supplies inventory $ 931 $ 849 Fuel inventory 286 313 Renewable energy certificates/emissions allowance inventory, net 11 15 Allowance for inventory obsolescence (73) (69) Inventories, net $ 1,155 $ 1,108

Deferred Costs, Capitalized, Pr

Deferred Costs, Capitalized, Prepaid, and Other Assets - Text Block	12 Months Ended
	Sep. 30, 2024
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Other Current Assets	5. Other Current Assets Other current assets consisted of the following: Other Current Assets At September 30 (in millions) 2024 2023 (1) Inventory work-in-progress $ 41 $ 28 Prepaid software maintenance 22 18 Prepaid insurance 19 16 Prepaid cloud assets 13 7 Current portion of prepaid long-term service agreements 7 25 Commodity contract derivative assets 5 21 Other 13 19 Other current assets $ 120 $ 134 Note (1) At September 30, 2023, $7 million previously classified as Other (a component of Other current assets) has been reclassified to Prepaid cloud assets (a component of Other current assets) to conform to current year presentation. Commodity Contract Derivative Assets. TVA enters into certain derivative contracts for natural gas that require physical delivery of the contracted quantity of the commodity as well as certain financial derivative contracts to hedge exposure to the price of natural gas. Commodity contract derivative assets classified as current include deliveries or settlements that will occur within 12 months or less. See Note 15 — Risk Management Activities and Derivative Transactions — Derivatives Not Receiving Hedge Accounting Treatment — Commodity Derivatives and — Commodity Derivatives under the FHP for a

Net Completed Plant

Net Completed Plant	12 Months Ended
	Sep. 30, 2024
Property, Plant and Equipment, Net, by Type [Abstract]
Property, Plant, and Equipment and Intangible Assets	6. Net Completed Plant Net completed plant consisted of the following: Net Completed Plant At September 30 (in millions) 2024 2023 Cost Accumulated Depreciation Cost Accumulated Depreciation Net Nuclear $ 26,800 $ 14,149 $ 12,651 $ 26,803 $ 13,557 $ 13,246 Coal-fired (1) 20,177 16,635 3,542 18,525 14,464 4,061 Gas and oil-fired 7,051 2,112 4,939 6,663 2,057 4,606 Transmission 9,964 3,450 6,514 9,375 3,359 6,016 Hydroelectric 4,307 1,288 3,019 4,109 1,241 2,868 Other electrical plant 1,763 737 1,026 1,798 780 1,018 Multipurpose dams 900 413 487 900 404 496 Other stewardship 27 9 18 26 9 17 Total $ 70,989 $ 38,793 $ 32,196 $ 68,199 $ 35,871 $ 32,328 Note (1) TVA recognized accelerated depreciation as a result of the decision to idle or retire certain units and the potential retirement of the remainder of the coal-fired fleet by 2035. See Note 7 — Plant Closures

Other Long-Term Assets _Text Bl

Other Long-Term Assets [Text Block]	12 Months Ended
	Sep. 30, 2024
Assets, Noncurrent [Abstract]
Other Long-Term Assets	9. Other Long-Term Assets The table below summarizes the types and amounts of TVA's other long-term assets: Other Long-Term Assets At September 30 (in millions) 2024 2023 (1) Loans and other long-term receivables, net $ 84 $ 97 Prepaid long-term service agreements 62 64 EnergyRight ® receivables, net 44 47 Cloud assets 35 15 Prepaid capital assets 29 28 Commodity contract derivative assets 2 12 Other 88 67 Total other long-term assets $ 344 $ 330 Note (1) At September 30, 2023, $15 million previously classified as Other (a component of Other long-term assets) has been reclassified to Cloud assets (a component of Other long-term assets) to conform to current year presentation. Loans and Other Long-Term Receivables . TVA's loans and other long-term receivables primarily consist of economic development loans for qualifying organizations and a receivable for reimbursements to recover the cost of providing long-term, on-site storage for spent nuclear fuel. The current and long-term portions of the loans receivable are reported in Accounts receivable, net and Other long-term assets, respectively, on TVA's Consolidated Balance Sheets. At September 30, 2024 and 2023, the carrying amount of the loans receivable, net of discount, reported in Accounts receivable, net was $21 million and $7 million, respectively. EnergyRight ® Receivables . In association with the EnergyRight ® program, TVA's local power company customers ("LPCs") offer financing to end-use customers for the purchase of energy-efficient equipment. Depending on the nature of the energy-efficiency project, loans may have a maximum term of five years or 10 years. TVA purchases the resulting loans receivable from its LPCs. The loans receivable are then transferred to a third-party bank with which TVA has agreed to repay in full any loans receivable that have been in default for 180 days or more or that TVA has determined are uncollectible. Given this continuing involvement, TVA accounts for the transfer of the loans receivable as secured borrowings. The current and long-term portions of the loans receivable are reported in Accounts receivable, net and Other long-term assets, respectively, on TVA's Consolidated Balance Sheets. At both September 30, 2024 and 2023, the carrying amount of the loans receivable, net of discount, reported in Accounts receivable, was $12 million. See Note 12 — Other Long-Term Liabilities for information regarding the associated financing obligation. Allowance for Loan Losses. The allowance for loan losses is an estimate of expected credit losses, measured over the estimated life of the loan receivables, that considers reasonable and supportable forecasts of future economic conditions in addition to information about historical experience and current conditions. See Note 1 — Summary of Significant Accounting Policies — Allowance for Uncollectible Accounts . The allowance components, which consist of a collective allowance and specific loans allowance, are based on the risk characteristics of TVA's loans. Loans that share similar risk characteristics are evaluated on a collective basis in measuring credit losses, while loans that do not share similar risk characteristics with other loans are evaluated on an individual basis. Allowance Components At September 30 (in millions) 2024 2023 EnergyRight ® loan reserve $ 1 $ 1 Economic development loan collective reserve — 1 Economic development loan specific loan reserve 1 1 Total allowance for loan losses $ 2 $ 3 Prepaid Long-Term Service Agreements. TVA has entered into various long-term service agreements for major maintenance activities at certain of its combined cycle plants. TVA uses the direct expense method of accounting for these arrangements. TVA accrues for parts when it takes ownership and for contractor services when they are rendered. Under certain of these agreements, payments made exceed the value of parts received and services rendered. The current and long-term portions of the resulting prepayments are reported in Other current assets and Other long-term assets, respectively, on TVA's Consolidated Balance Sheets. At September 30, 2024 and 2023, prepayments of $7 million and $25 million, respectively, were recorded in Other current assets. Cloud Assets. TVA has capitalized the implementation costs of hosting arrangements that are considered service contracts as cloud assets. The cloud assets are amortized over the term of the associated hosting arrangements. The current and long-term portions of the cloud assets are reported in Other current assets and Other long-term assets, respectively, on TVA’s Consolidated Balance Sheets. At September 30, 2024, and September 30, 2023, the carrying amount of the cloud assets reported in Other current assets was $13 million and $7 million, respectively. Commodity Contract Derivative Assets. TVA enters into certain derivative contracts for natural gas that require physical delivery of the contracted quantity of the commodity as well as certain financial derivative contracts to hedge exposure to the price of natural gas. See Note 15 — Risk Management Activities and Derivative Transactions — Derivatives Not Receiving Hedge Accounting Treatment — Commodity Derivatives and — Commodity Derivatives under the FHP for a

Regulatory Assets and Liabiliti

Regulatory Assets and Liabilities [Text Block]	12 Months Ended
	Sep. 30, 2024
Regulatory Assets and Liabilities Disclosure [Abstract]
Regulatory Assets and Liabilities	10. Regulatory Assets and Liabilities TVA records certain assets and liabilities that result from the regulated ratemaking process that would not be recorded under GAAP for non-regulated entities. As such, certain items that would generally be reported in earnings or that would impact the Consolidated Statements of Operations are recorded as regulatory assets or regulatory liabilities. Regulatory assets generally represent incurred costs that have been deferred because such costs are probable of future recovery in customer rates. Regulatory liabilities generally represent obligations to make refunds to customers for previous collections for costs that are not likely to be incurred or deferral of gains that will be credited to customers in future periods. Components of regulatory assets and regulatory liabilities are summarized in the table below. Regulatory Assets and Liabilities At September 30 (in millions) 2024 2023 Current regulatory assets Unrealized losses on commodity derivatives $ 102 $ 136 Unrealized losses on interest rate derivatives 54 31 Fuel cost adjustment receivable 35 11 Total current regulatory assets 191 178 Non-current regulatory assets Non-nuclear decommissioning costs 6,187 2,922 Retirement benefit plans deferred costs 1,979 1,440 Unrealized losses on interest rate derivatives 447 272 Nuclear decommissioning costs 362 728 Environmental compliance and remediation costs 215 — Unrealized losses on commodity derivatives 64 52 Other non-current regulatory assets 154 152 Total non-current regulatory assets 9,408 5,566 Total regulatory assets $ 9,599 $ 5,744 Current regulatory liabilities Fuel cost adjustment tax equivalents $ 169 $ 201 Unrealized gains on commodity derivatives 5 21 Total current regulatory liabilities 174 222 Non-current regulatory liabilities Retirement benefit plans deferred credits 81 95 Unrealized gains on commodity derivatives 2 12 Total non-current regulatory liabilities 83 107 Total regulatory liabilities $ 257 $ 329 Retirement Benefit Plans Deferred Costs (Credits) . TVA measures the funded status of its pension and post-retirement ("OPEB") benefit plans at each year-end balance sheet date. The funded status is measured as the difference between the fair value of plan assets and the benefit obligations at the measurement date for each plan. The changes in funded status are actuarial gains and losses that are recognized on TVA's Consolidated Balance Sheets by adjusting the recognized pension and OPEB liabilities, with the offset deferred as a regulatory asset or a regulatory liability. In an unregulated environment, these deferred costs (credits) would be recognized as an increase or decrease to accumulated other comprehensive income (loss) ("AOCI"). "Incurred cost" is a cost arising from cash paid out or an obligation to pay for an acquired asset or service, and a loss from any cause that has been sustained and for which payment has been or must be made. In the cases of pension and OPEB costs, the unfunded obligation represents a projected liability to the employee for services rendered, and thus it meets the definition of an incurred cost. Therefore, amounts that otherwise would be charged to AOCI for these costs are recorded as a regulatory asset or liability since TVA has historically recovered pension and OPEB expense in rates. Through historical and current year expense included in ratemaking, the TVA Board has demonstrated the ability and intent to include pension and OPEB costs in allowable costs and in rates for ratemaking purposes. As a result, it is probable that future revenue will result from inclusion of the pension and OPEB regulatory assets or regulatory liability in allowable costs for ratemaking purposes. The regulatory asset and liability are classified as long-term, which is consistent with the pension and OPEB liabilities, and are not amortized to the Consolidated Statements of Operations over a specified recovery period. They are adjusted either upward or downward each year in conjunction with the adjustments to the unfunded pension liability and OPEB liability, as calculated by the actuaries. Ultimately the regulatory asset and liability will be recognized in the Consolidated Statements of Operations in the form of pension and OPEB expense as the actuarial liabilities are eliminated in future periods. See Note 20 — Benefit Plans — Obligations and Funded Status . Additionally on October 1, 2014, TVA began recognizing pension costs as a regulatory asset to the extent that the amount calculated under GAAP as pension expense differs from the amount TVA contributes to the pension plan. As a result of previous plan design changes, future contributions are expected to exceed the expense calculated under U.S. GAAP. Accordingly, TVA discontinued this regulatory accounting practice as all such deferred costs were recovered as of September 30, 2024. Non-Nuclear Decommissioning Costs. Non-nuclear decommissioning costs include (1) certain deferred charges related to the future closure and decommissioning of TVA's non-nuclear long-lived assets, (2) recognition of changes in the liability, (3) recognition of changes in the value of TVA's ART, and (4) certain other deferred charges under the accounting rules for asset retirement obligations ("AROs"). TVA has established the ART to more effectively segregate, manage, and invest funds to help meet future non-nuclear AROs. The funds from the ART may be used, among other things, to pay the costs related to the future closure and retirement of non-nuclear long-lived assets under various legal requirements. These future costs can be funded through a combination of investment funds set aside in the ART, future earnings on those investment funds, and future cash contributions to the ART. In 2024 and 2023, TVA recovered in rates an amount determined by the average life of debt financed for non-nuclear decommissioning expenditures, assuming a 20-year debt service period, and contributions to the ART. Deferred charges will be recovered in rates based on an analysis of the expected expenditures, contributions, and investment earnings required to recover the decommissioning costs. Recovery of future decommissioning costs is dependent upon the future earnings of the ART, timing of decommissioning activities, and changes in decommissioning estimates. The regulatory asset is classified as long-term as amounts recovered are used to service debt or to contribute to the ART, which is restricted for future decommissioning costs. During 2024, TVA recorded additional estimated AROs of $3.1 billion as a result of the Environmental Protection Agency's ("EPA's") final legacy coal combustion residual ("CCR") rule ("Legacy CCR Rule") and recorded a corresponding regulatory asset of $3.1 billion due to these AROs being associated with closed sites and asset retirement costs having been fully depreciated. See Note 13 — Asset Retirement Obligations. Environmental Compliance and Remediation Costs. TVA uses regulatory accounting for certain amounts associated with compliance with an order, regulation, settlement, or lawsuit, or certain costs associated with environmental remediation activities, including but not limited to those involving environmental cleanup activities and groundwater activities. Costs will be recovered in rates based on the average life of debt financed to fund actual expenditures. See Note 22 — Contingencies and Legal Proceedings — Contingencies — Environmental Matters. Unrealized Losses on Interest Rate Derivatives . TVA uses regulatory accounting treatment to defer the unrealized gains and losses on certain interest rate derivative contracts. When amounts in these contracts are realized, the resulting gains or losses are included in the ratemaking formula. The unrealized losses on these interest rate derivatives are recorded on TVA's Consolidated Balance Sheets as current and non-current regulatory assets, and the related realized gains or losses, if any, are recorded on TVA's Consolidated Statements of Operations when the contracts settle. A portion of certain unrealized gains and losses will be amortized into earnings over the remaining lives of the contracts. Gains and losses on interest rate derivatives that are expected to be realized within the next year are included as a current regulatory asset or liability on TVA's Consolidated Balance Sheets. TVA does not recognize unrealized gains and losses from the investment portfolios and derivative instruments within earnings but rather defers all such gains and losses within a regulatory liability or asset in accordance with its accounting policy. See Note 15 — Risk Management Activities and Derivative Transactions and Note 16 — Fair Value Measurements. Nuclear Decommissioning Costs. Nuclear decommissioning costs include (1) certain deferred charges related to the future closure and decommissioning of TVA's nuclear generating units under the Nuclear Regulatory Commission ("NRC") requirements, (2) recognition of changes in the liability, (3) recognition of changes in the value of TVA's NDT, and (4) certain other deferred charges under the accounting rules for AROs. These future costs can be funded through a combination of investment funds set aside in the NDT and ART and future earnings on those investment funds. Deferred charges will be recovered in rates based on the analysis of expected expenditures, contributions, and investment earnings required to recover the decommissioning costs. See Note 1 — Summary of Significant Accounting Policies — Investment Funds. Recovery of future decommissioning costs is dependent upon the future earnings of the NDT and ART, timing of decommissioning activities, and changes in decommissioning estimates. The regulatory asset is classified as long-term as amounts recovered are contributed to the NDT or the ART, which are restricted for future decommissioning costs. See Note 13 — Asset Retirement Obligations and Note 16 — Fair Value Measurements. Unrealized Gains (Losses) on Commodity Derivatives. TVA enters into certain derivative contracts for natural gas that require the physical delivery of the contracted quantity of the commodity. Unrealized gains (losses) on natural gas purchase contracts, included as part of unrealized gains (losses) on commodity derivatives, relate to the mark-to-market ("MtM") valuation of natural gas purchase contracts. The natural gas purchase contracts qualify as derivative contracts but do not qualify for cash flow hedge accounting treatment. As a result, TVA recognizes the changes in the market value of these derivative contracts as a regulatory liability or asset. This treatment reflects TVA's ability and intent to recover the cost of these commodity contracts on a settlement basis for ratemaking purposes through the fuel cost adjustment. TVA recognizes the actual cost of fuel received under these contracts in fuel and purchased power expense at the time the fuel is used to generate electricity. These contracts expire at various times through December 2028. Unrealized gains and losses on contracts with a maturity of less than one year are included as a current regulatory asset or liability on TVA's Consolidated Balance Sheets. See Note 15 — Risk Management Activities and Derivative Transactions . Currently, TVA is hedging exposure to the price of natural gas under the Financial Hedging Program ("FHP"). Deferred gains and losses relating to TVA's FHP are included as part of unrealized gains and losses on commodity derivatives. TVA defers all MtM unrealized gains or losses as regulatory liabilities or assets, respectively, and records the realized gains or losses in fuel and purchased power expense as the contracts settle to match the delivery period of the underlying commodity. These contracts expire at various times through March 2028. This accounting treatment reflects TVA's ability and intent to include the realized gains or losses of these commodity contracts in future periods through the fuel cost adjustment. Net unrealized gains and losses for any settlements that occur within 12 months or less are classified as a current regulatory liability or asset on TVA's Consolidated Balance Sheets. See Note 15 — Risk Management Activities and Derivative Transactions. Fuel Cost Adjustment Receivable. The fuel cost adjustment provides a mechanism to alter rates monthly to reflect changing fuel and purchased power costs. There is typically a lag between the occurrence of a change in fuel and purchased power costs and the reflection of the change in fuel rates. Balances in the fuel cost adjustment regulatory accounts represent over-collected or under-collected revenues that offset fuel and purchased power costs, and the fuel rate is designed to recover or refund the balance in less than one year. Other Non-Current Regulatory Assets. Other non-current regulatory assets consist of the following: Deferred Lease Asset and Other Financing Obligations . For certain leases, TVA recognized the initial finance lease and other financing asset and liability at inception of the lease or other obligation. However, the annual expense recognized in rates is equal to the annual payments, which differs from GAAP treatment for non-regulated entities. This practice results in TVA's asset balances being higher than they otherwise would have been under GAAP, with the difference representing a regulatory asset related to the lease or other financing obligation. These costs will be amortized over the respective lease or other financing obligation terms as payments are made. As the costs associated with this regulatory asset are not currently being considered in rates and the asset is expected to increase over the next year, the regulatory asset has been classified as long-term. Debt Reacquisition Costs . Reacquisition expenses, call premiums, and other related costs, such as unamortized debt issue costs associated with redeemed Bond issues, are deferred and amortized (accreted) on a straight-line basis over the weighted average life of TVA's debt portfolio. Because timing of additional reacquisition expenses and changes to the weighted average life of the debt are uncertain, the regulatory asset is classified as long-term. Retirement Removal Costs . Retirement removal costs, net of salvage, that are not legally required are recognized as a regulatory asset. Net removal costs are amortized over a one-year period subsequent to completion of the removal activities. TVA treats this regulatory asset as long-term in its entirety primarily because it relates to assets that are long-term in nature. Fuel Cost Adjustment Tax Equivalents.

Variable Interest Entities (Tex

Variable Interest Entities (Text Block)	12 Months Ended
	Sep. 30, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Variable Interest Entities	11. Variable Interest Entities A VIE is an entity that either (i) has insufficient equity to permit the entity to finance its activities without additional subordinated financial support or (ii) has equity investors who lack the characteristics of owning a controlling financial interest. When TVA determines that it has a variable interest in a VIE, a qualitative evaluation is performed to assess which interest holders have the power to direct the activities that most significantly impact the economic performance of the entity and have the obligation to absorb losses or receive benefits that could be significant to the entity. The evaluation considers the purpose and design of the business, the risks that the business was designed to create and pass along to other entities, the activities of the business that can be directed and which party can direct them, and the expected relative impact of those activities on the economic performance of the business through its life. TVA has the power to direct the activities of an entity when it has the ability to make key operating and financing decisions, including, but not limited to, capital investment and the issuance of debt. Based on the evaluation of these criteria, TVA has determined it is the primary beneficiary of certain entities and as such is required to account for the VIEs on a consolidated basis. John Sevier VIEs In 2012, TVA entered into a $1.0 billion construction management agreement and lease financing arrangement with John Sevier Combined Cycle Generation LLC ("JSCCG") for the completion and lease by TVA of the John Sevier Combined Cycle Facility ("John Sevier CCF"). JSCCG is a special single-purpose limited liability company formed in January 2012 to finance the John Sevier CCF through a $900 million secured note issuance (the "JSCCG notes") and the issuance of $100 million of membership interests subject to mandatory redemption. The membership interests were purchased by John Sevier Holdco LLC ("Holdco"). Holdco is a special single-purpose entity, also formed in January 2012, established to acquire and hold the membership interests in JSCCG. A non-controlling interest in Holdco is held by a third-party through nominal membership interests, to which none of the income, expenses, and cash flows are allocated. The membership interests held by Holdco in JSCCG were purchased with proceeds from the issuance of $100 million of secured notes (the "Holdco notes") and are subject to mandatory redemption pursuant to a schedule of amortizing, semi-annual payments due each January 15 and July 15, with a final payment due in January 2042. The payment dates for the mandatorily redeemable membership interests are the same as those of the Holdco notes. The sale of the JSCCG notes, the membership interests in JSCCG, and the Holdco notes closed in January 2012. The JSCCG notes are secured by TVA's lease payments, and the Holdco notes are secured by Holdco's investment in, and amounts receivable from, JSCCG. TVA's lease payments to JSCCG are equal to and payable on the same dates as JSCCG's and Holdco's semi-annual debt service payments. In addition to the lease payments, TVA pays administrative and miscellaneous expenses incurred by JSCCG and Holdco. Certain agreements related to this transaction contain default and acceleration provisions. Due to its participation in the design, business activity, and credit and financial support of JSCCG and Holdco, TVA has determined that it has a variable interest in each of these entities. Based on its analysis, TVA has concluded that it is the primary beneficiary of JSCCG and Holdco and, as such, is required to account for the VIEs on a consolidated basis. Holdco's membership interests in JSCCG are eliminated in consolidation. Southaven VIE In 2013, TVA entered into a $400 million lease financing arrangement with Southaven Combined Cycle Generation LLC ("SCCG") for the lease by TVA of the Southaven Combined Cycle Facility ("Southaven CCF"). SCCG is a special single-purpose limited liability company formed in June 2013 to finance the Southaven CCF through a $360 million secured notes issuance (the "SCCG notes") and the issuance of $40 million of membership interests subject to mandatory redemption. The membership interests were purchased by Southaven Holdco LLC ("SHLLC"). SHLLC is a special single-purpose entity, also formed in June 2013, established to acquire and hold the membership interests in SCCG. A non-controlling interest in SHLLC is held by a third-party through nominal membership interests, to which none of the income, expenses, and cash flows of SHLLC are allocated. The membership interests held by SHLLC were purchased with proceeds from the issuance of $40 million of secured notes (the "SHLLC notes") and are subject to mandatory redemption pursuant to a schedule of amortizing, semi-annual payments due each February 15 and August 15, with a final payment due on August 15, 2033. The payment dates for the mandatorily redeemable membership interests are the same as those of the SHLLC notes, and the payment amounts are sufficient to provide returns on, as well as returns of, capital until the investment has been repaid to SHLLC in full. The rate of return on investment to SHLLC is seven percent, which is reflected as interest expense in the Consolidated Statements of Operations. SHLLC is required to pay a pre-determined portion of the return on investment to Seven States Southaven, LLC ("SSSL") on each lease payment date as agreed in SHLLC's formation documents (the "Seven States Return"). The current and long-term portions of the Membership interests of VIE subject to mandatory redemption are included in Accounts payable and accrued liabilities and Other long-term liabilities, respectively. The payment dates for the mandatorily redeemable membership interests are the same as those of the SHLLC notes. The SCCG notes are secured by TVA's lease payments, and the SHLLC notes are secured by SHLLC's investment in, and amounts receivable from, SCCG. TVA's lease payments to SCCG are payable on the same dates as SCCG's and SHLLC's semi-annual debt service payments and are equal to the sum of (i) the amount of SCCG's semi-annual debt service payments, (ii) the amount of SHLLC's semi-annual debt service payments, and (iii) the amount of the Seven States Return. In addition to the lease payments, TVA pays administrative and miscellaneous expenses incurred by SCCG and SHLLC. Certain agreements related to this transaction contain default and acceleration provisions. In the event that TVA were to choose to exercise an early buy out feature of the Southaven facility lease, in part or in whole, TVA must pay to SCCG amounts sufficient for SCCG to repay or partially repay on a pro rata basis the membership interests held by SHLLC, including any outstanding investment amount plus accrued but unpaid return. TVA also has the right, at any time and without any early redemption of the other portions of the Southaven facility lease payments due to SCCG, to fully repay SHLLC's investment, upon which repayment SHLLC will transfer the membership interests to a designee of TVA. TVA participated in the design, business activity, and financial support of SCCG and has determined that it has a direct variable interest in SCCG resulting from risk associated with the value of the Southaven CCF at the end of the lease term. Based on its analysis, TVA has determined that it is the primary beneficiary of SCCG and, as such, is required to account for the VIE on a consolidated basis. Impact on Consolidated Financial Statements The financial statement items attributable to carrying amounts and classifications of JSCCG, Holdco, and SCCG as of September 30, 2024 and 2023, as reflected on the Consolidated Balance Sheets, are as follows: Summary of Impact of VIEs on Consolidated Balance Sheets At September 30 (in millions) 2024 2023 Current liabilities Accrued interest $ 9 $ 9 Accounts payable and accrued liabilities 1 1 Current maturities of long-term debt of variable interest entities 37 35 Total current liabilities 47 45 Other liabilities Other long-term liabilities 16 17 Long-term debt, net Long-term debt of variable interest entities, net 897 933 Total liabilities $ 960 $ 995 Interest expense of $46 million, $48 million, and $50 million related to debt of VIEs and membership interests of variable interest entity subject to mandatory redemption is included on the Consolidated Statements of Operations for the years ended September 30, 2024, 2023, and 2022, respectively. At September 30, 2024, TVA had outstanding debt of VIEs of $934 million and outstanding membership interests subject to mandatory redemption (including current portion) of $17 million issued by one of its VIEs of which it is the primary beneficiary. The following table sets forth TVA's future payments at September 30, 2024: Maturities Due in the Year Ending September 30 (in millions) 2025 2026 2027 2028 2029 Thereafter Long-term debt of VIEs including current maturities (1) $ 37 $ 39 $ 40 $ 42 $ 44 $ 737 Membership interests of variable interest entity subject to mandatory redemption 1 1 1 1 2 11 Note (1) Long-term debt of VIEs does not include non-cash item of unamortized debt issue costs of $5 million. Creditors of the VIEs do not have any recourse to the general credit of TVA. TVA does not have any obligations to provide financial support to the VIEs other than as prescribed in the terms of the agreements related to these transactions.

Other Long-Term Liabilities

Other Long-Term Liabilities	12 Months Ended
	Sep. 30, 2024
Other Liabilities, Noncurrent [Abstract]
Other Long-Term Liabilities	12. Other Long-Term Liabilities Other long-term liabilities consist primarily of liabilities related to certain derivative agreements as well as liabilities related to operating leases. The table below summarizes the types and amounts of Other long-term liabilities: Other Long-Term Liabilities At September 30 (in millions) 2024 2023 (1) Interest rate swap liabilities $ 792 $ 627 Environmental compliance and remediation costs 212 — Long-term project cost accruals 140 10 Currency swap liabilities 109 131 Operating lease liabilities 88 93 Commodity contract derivative liabilities 64 52 Advances for construction 55 56 EnergyRight ® financing obligation 52 55 Long-term deferred compensation 50 41 Long-term deferred revenue 48 45 Other 102 101 Total other long-term liabilities $ 1,712 $ 1,211 Note (1) At September 30, 2023, $10 million previously classified as Other (a component of Other long-term liabilities) has been reclassified to Long-term project cost accruals (a component of Other long-term liabilities) to conform with current year presentation. Interest Rate Swap Liabilities . TVA uses interest rate swaps to fix variable short-term debt to a fixed rate. The values of these derivatives are included in Other current assets, Accounts payable and accrued liabilities, Accrued interest, and Other long-term liabilities on the Consolidated Balance Sheets. See Note 15 — Risk Management Activities and Derivative Transactions — Overview of Accounting Treatment and Derivatives Not Receiving Hedge Accounting Treatment — Interest Rate Derivative s for information regarding the interest rate swap liabilities. Operating Lease Liabilities . TVA's operating leases consist primarily of railcars, equipment, real estate/land, and power generating facilities. At September 30, 2024 and 2023, the current portion of TVA's operating leases reported in Accounts payable and accrued liabilities was $ 63 million 71 million Leases for more information regarding leases. Currency Swap Liabilities . To protect against exchange rate risk related to British pound sterling denominated Bond transactions, TVA entered into foreign currency hedges. The values of these derivatives are included in Accounts payable and accrued liabilities and Other long-term liabilities on the Consolidated Balance Sheets. See Note 15 — Risk Management Activities and Derivative Transactions — Overview of Accounting Treatment and Cash Flow Hedging Strategy for Currency Swaps for more information regarding the currency swap liabilities. Commodity Contract Derivative Liabilities. TVA enters into certain derivative contracts for natural gas that require physical delivery of the contracted quantity of the commodity as well as certain financial derivative contracts to hedge exposure to the price of natural gas. See Note 15 — Risk Management Activities and Derivative Transactions — Derivatives Not Receiving Hedge Accounting Treatment — Commodity Derivatives and — Commodity Derivatives under the FHP for a discussion of TVA's commodity contract derivatives. EnergyRight ® Financing Obligation . TVA purchases certain loans receivable from its LPCs in association with the EnergyRight ® program. The current and long-term portions of the resulting financing obligation are reported in Accounts payable and accrued liabilities and Other long-term liabilities, respectively, on TVA's Consolidated Balance Sheets. At September 30, 2024 and 2023, the carrying amount of the financing obligation reported in Accounts payable and accrued liabilities was $13 million and $14 million respectively. See Note 9 — Other Long-Term Assets for information regarding the associated loans receivable. Long-Term Deferred Compensation . TVA provides compensation arrangements to engage and retain certain employees, both executive and non-executive, which are designed to provide participants with the ability to defer compensation to future periods. The current and long-term portions are recorded in Accounts payable and accrued liabilities and Other long-term liabilities, respectively, on TVA’s Consolidated Balance Sheets. At September 30, 2024 and 2023, the current amount of deferred compensation recorded in Accounts payable and accrued liabilities was $74 million and $65 million, respectively. Advances for Construction. TVA receives refundable and non-refundable advances for construction that are generally intended to defray all or a portion of the costs of building or extending TVA’s existing power assets. Amounts received are deferred as a liability with the long-term portion representing amounts that will not be recognized within the next 12 months. As projects meet milestones or other contractual obligations, the refundable portion is refunded to the customer and the non-refundable portion is recognized as contributions in aid of construction and offsets the cost of plant assets. At September 30, 2024 and 2023, the current amount of advances for construction recorded in Accounts payable and accrued liabilities was $60 million and $39 million, respectively. Long-Term Deferred Revenue . Long-term deferred revenue represents payments received that exceed services rendered resulting in the deferral of revenue. This long-term portion represents amounts that will not be recognized within the next 12 months primarily related to fiber and transmission agreements. The current and long-term portions of the deferral are recorded in Accounts payable and accrued liabilities and Other long-term liabilities, respectively, on TVA’s Consolidated Balance Sheets. At September 30, 2024 and 2023, the current amount of deferred revenue recorded in Accounts payable and accrued liabilities was $28 million and $21 million, respectively. Environmental Compliance and Remediation Costs . Environmental compliance and remediation costs represent certain costs associated with environmental remediation activities, including but not limited to those involving environmental cleanup activities and groundwater activities. The current and long-term portions of environmental compliance and remediation costs are reported in Accounts payable and accrued liabilities and Other long-term liabilities, respectively, on TVA's Consolidated Balance Sheets. At September 30, 2024, the current amount of the environmental compliance and remediation costs reported in Accounts payable and accrued liabilities was $3 million. There were no current amounts at September 30, 2023. Long-Term Project Cost Accruals

Debt and Other Obligations

Debt and Other Obligations	12 Months Ended
	Sep. 30, 2024
Debt Disclosure [Abstract]
Debt and Other Obligations	14. Debt and Other Obligations General The TVA Act authorizes TVA to issue Bonds in an amount not to exceed $30.0 billion at any time. At September 30, 2024, TVA had only two types of Bonds outstanding: power bonds and discount notes. Power bonds have maturities between one year and 50 years, and discount notes have maturities of less than one year. Power bonds and discount notes are both issued pursuant to Section 15d of the TVA Act and pursuant to the Basic Tennessee Valley Authority Power Bond Resolution adopted by the TVA Board on October 6, 1960, as amended on September 28, 1976, October 17, 1989, and March 25, 1992 (the "Basic Resolution"). Bonds are not obligations of the U.S., and the U.S. does not guarantee the payments of principal or interest on Bonds. Power bonds and discount notes rank on parity and have first priority of payment from net power proceeds, which are defined as the remainder of TVA's gross power revenues after deducting the costs of operating, maintaining, and administering its power properties and tax equivalent payments, but before deducting depreciation accruals or other charges representing the amortization of capital expenditures, plus the net proceeds from the sale or other disposition of any power facility or interest therein. TVA considers its scheduled payments under its lease financing arrangements involving John Sevier CCF and Southaven CCF as costs of operating, maintaining, and administering its power properties. Costs of operating, maintaining, and administering TVA's power properties have priority over TVA's payments on the Bonds. Once net power proceeds have been applied to payments on power bonds and discount notes as well as any other Bonds that TVA may issue in the future that rank on parity with or subordinate to power bonds and discount notes, Section 2.3 of the Basic Resolution provides that the remaining net power proceeds shall be used only for (1) minimum payments into the U.S. Treasury required by the TVA Act as repayment of, and as a return on, the Power Program Appropriation Investment; (2) investment in power system assets; (3) additional reductions of TVA's capital obligations; and (4) other lawful purposes related to TVA's power business. The TVA Act and the Basic Resolution each contain two bond tests: the rate test and the bondholder protection test. Under the rate test, TVA must charge rates for power which will produce gross revenues sufficient to provide funds for, among other things, debt service on outstanding Bonds. As of September 30, 2024, TVA was in compliance with the rate test. Under the bondholder protection test, TVA must, in successive five-year periods, use an amount of net power proceeds at least equal to the sum of (1) the depreciation accruals and other charges representing the amortization of capital expenditures and (2) the net proceeds from any disposition of power facilities for either the reduction of its capital obligations (including Bonds and the Power Program Appropriation Investment) or investment in power assets. TVA met the bondholder protection test for the five-year period ended September 30, 2020, and must next meet the bondholder protection test for the five-year period ending September 30, 2025 . Secured Debt of VIEs On August 9, 2013, SCCG issued secured notes totaling $360 million that bear interest at a rate of 3.846 percent. The SCCG notes require amortizing semi-annual payments on each February 15 and August 15, and mature on August 15, 2033. Also on August 9, 2013, SCCG issued $40 million of membership interests subject to mandatory redemption. The proceeds from the secured notes issuance and the issuance of the membership interests were paid to TVA in accordance with the terms of the Southaven head lease. See Note 11 — Variable Interest Entities — Southaven VIE . TVA used the proceeds from the transaction primarily to fund the acquisition of the Southaven CCF from SSSL. On January 17, 2012, JSCCG issued secured notes totaling $900 million in aggregate principal amount that bear interest at a rate of 4.626 percent. Also on January 17, 2012, Holdco issued secured notes totaling $100 million that bear interest at a rate of 7.1 percent. The JSCCG notes and the Holdco notes require amortizing semi-annual payments on each January 15 and July 15, and mature on January 15, 2042. The Holdco notes require a $10 million balloon payment upon maturity. See Note 11 — Variable Interest Entities — John Sevier VIEs . TVA used the proceeds from the transaction to meet its requirements under the TVA Act. Secured debt of VIEs, including current maturities, outstanding at September 30, 2024 and 2023 totaled $934 million and $968 million, respectively. Short-Term Debt The following table provides information regarding TVA's short-term borrowings: Short-Term Borrowings At September 30 2024 2023 Gross amount outstanding - discount notes (in millions) $ 1,168 $ 432 Weighted average interest rate - discount notes 4.76 % 5.29 % Put Options TVA has two issues of Putable Automatic Rate Reset Securities ("PARRS") outstanding. After a fixed-rate period of five years, the coupon rate on the PARRS may automatically be reset downward under certain market conditions on an annual basis. The coupon rate reset on the PARRS is based on a calculation. For both series of PARRS, the coupon rate will reset downward on the reset date if the rate calculated is below the then-current coupon rate on the Bond. The calculation dates, potential reset dates, and terms of the calculation are different for each series. The coupon rate on the 1998 Series D PARRS may be reset on June 1 (annually) if the sum of the five-day average of the 30-Year Constant Maturity Treasury ("CMT") rate for the week ending the last Friday in April, plus 94 basis points, is below the then-current coupon rate. The coupon rate on the 1999 Series A PARRS may be reset on May 1 (annually) if the sum of the five-day average of the 30-Year CMT rate for the week ending the last Friday in March, plus 84 basis points, is below the then-current coupon rate. The coupon rates may only be reset downward, but investors may request to redeem their Bonds at par value in conjunction with a coupon rate reset for a limited period of time prior to the reset dates under certain circumstances. The coupon rate for the 1998 Series D PARRS, which mature in June 2028, has been reset eight times, from an initial rate of 6.750 percent to the current rate of 2.134 percent. In connection with these resets, $318 million of the Bonds have been redeemed; therefore, $256 million of the Bonds were outstanding at September 30, 2024. The coupon rate for the 1999 Series A PARRS, which mature in May 2029, has been reset seven times, from an initial rate of 6.50 percent to the current rate of 2.216 percent. In connection with these resets, $316 million of the Bonds have been redeemed; therefore, $208 million of the Bonds were outstanding at September 30, 2024. Due to the contingent nature of the put option on the PARRS, TVA determines whether the PARRS should be classified as long-term debt or current maturities of long-term debt by calculating the expected reset rate for the Bonds on the calculation dates, described above. If the determination date for reset is before the balance sheet date of the reporting period and the expected reset rate is less than the then-current coupon rate on the PARRS, the PARRS are included in current maturities. Otherwise, the PARRS are included in long-term debt. Debt Securities Activity The table below summarizes the long-term debt securities activity for the years ended September 30, 2024 and 2023. Debt Securities Activity For the years ended September 30 (in millions) 2024 2023 Issues 2023 Series A (1) $ — $ 1,000 2024 Series A (2) 1,000 — Discount on debt issues (9) (8) Total $ 991 $ 992 Redemptions/Maturities (3) 2009 Series B $ 22 $ 29 2014 Series A 1,000 — Total redemptions/maturities of power bonds 1,022 29 Debt of variable interest entities 35 39 Total redemptions/maturities of debt $ 1,057 $ 68 Notes (1) The 2023 Series A Bonds were issued at 99.187 percent of par. (2) The 2024 Series A Bonds were issued at 99.109 percent of par. (3) All redemptions were at 100 percent of par. Debt Outstanding Total debt outstanding at September 30, 2024 and 2023, consisted of the following: Short-Term Debt At September 30 (in millions) CUSIP or Other Identifier Maturity 2024 2023 Short-term debt, net of discounts $ 1,167 $ 432 Current maturities of long-term debt of VIEs issued at par 37 35 Current maturities of power bonds issued at par 880591ER9 9/15/2024 2.875% — 1,000 880591EF5 12/15/2024 3.770% 1 1 880591EW8 5/15/2025 0.750% 1,000 — 880591EF5 6/15/2025 3.770% 21 21 Total current maturities of power bonds issued at par 1,022 1,022 Total current debt outstanding, net $ 2,226 $ 1,489 Long-Term Debt At September 30 (in millions) CUSIP or Other Identifier Maturity Coupon 2024 Par 2023 Par Stock Exchange Listings 880591EW8 5/15/2025 0.750% $ — $ 1,000 New York 880591CJ9 11/1/2025 6.750% 1,350 1,350 New York, Hong Kong, Luxembourg, Singapore 880591EU2 2/1/2027 2.875% 1,000 1,000 New York 880591EZ1 3/15/2028 3.875% 1,000 1,000 New York 880591300 (1) 6/1/2028 2.134% 256 256 New York 880591409 (1) 5/1/2029 2.216% 208 208 New York 880591DM1 5/1/2030 7.125% 1,000 1,000 New York, Luxembourg 880591EX6 9/15/2031 1.500% 500 500 New York 880591DP4 6/7/2032 6.587% (2) 335 (3) 305 (3) New York, Luxembourg 880591DV1 7/15/2033 4.700% 472 472 New York, Luxembourg 880591EF5 6/15/2034 3.770% 116 139 None 880591FB3 8/1/2034 4.375% 1,000 — New York 880591DX7 6/15/2035 4.650% 436 436 New York 880591CK6 4/1/2036 5.980% 121 121 New York 880591CS9 4/1/2036 5.880% 1,500 1,500 New York 880591CP5 1/15/2038 6.150% 1,000 1,000 New York 880591ED0 6/15/2038 5.500% 500 500 New York 880591EH1 9/15/2039 5.250% 2,000 2,000 New York 880591EP3 12/15/2042 3.500% 1,000 1,000 New York 880591DU3 6/7/2043 4.962% (2) 201 (3) 183 (3) New York, Luxembourg 880591EB4 1/15/2048 4.875% 500 500 New York, Luxembourg 880591EY4 9/15/2052 4.250% 500 500 New York 880591DZ2 4/1/2056 5.375% 1,000 1,000 New York 880591EJ7 9/15/2060 4.625% 1,000 1,000 New York 880591ES7 9/15/2065 4.250% 1,000 1,000 New York Subtotal 17,995 17,970 Unamortized discounts, premiums, issue costs, and other (128) (126) Total long-term outstanding power bonds, net 17,867 17,844 Long-term debt of VIEs, net 897 933 Total long-term debt, net $ 18,764 $ 18,777 Notes (1) TVA PARRS, CUSIP numbers 880591300 and 880591409, may be redeemed under certain conditions. See Put Options above. (2) The coupon rate represents TVA's effective interest rate. (3) CUSIP numbers 880591DP4 and 880591DU3 include total net exchange gain from currency transactions of $62 million and $109 million at September 30, 2024 and 2023, respectively. Maturities Due in the Year Ending September 30 (in millions) 2025 2026 2027 2028 2029 Thereafter Total Long-term power bonds including current maturities (1) $ 1,022 $ 1,370 $ 1,020 $ 1,272 $ 220 $ 14,175 $ 19,079 Short-term debt net of discounts 1,167 — — — — — 1,167 Notes (1) Long-term power bonds do not include non-cash items of foreign currency exchange gain of $62 million, unamortized debt issue costs of $41 million, or net discount on sale of Bonds of $87 million. Credit Facility Agreements TVA has funding available under four long-term revolving credit facilities totaling $2.7 billion. See the table below for additional information on the four long-term revolving credit facilities. The interest rate on any borrowing under these facilities varies based on market factors and the rating of TVA's senior unsecured, long-term, non-credit-enhanced debt. TVA is required to pay an unused facility fee on the portion of the total $2.7 billion that TVA has not borrowed or committed under letters of credit. This fee, along with letter of credit fees, may fluctuate depending on the rating of TVA's senior unsecured, long-term, non-credit-enhanced debt. At September 30, 2024 and 2023, there were $566 million and $535 million, respectively, of letters of credit outstanding under these facilities, and there were no borrowings outstanding. TVA's letters of credit are primarily posted as collateral under TVA's interest rate swaps. See Note 15 — Risk Management Activities and Derivative Transactions — Other Derivative Instruments — Collateral . TVA may also post collateral for TVA's currency swaps, for commodity derivatives under the FHP, or for certain transactions with third parties that require TVA to post letters of credit. The following table provides additional information regarding TVA's funding available under the four long-term revolving credit facilities: Summary of Long-Term Credit Facilities At September 30, 2024 (in millions) Maturity Date Facility Limit Letters of Credit Outstanding Cash Borrowings Availability March 2026 $ 150 $ 38 $ — $ 112 September 2026 1,000 134 — 866 March 2027 1,000 180 — 820 February 2028 500 214 — 286 Total $ 2,650 $ 566 $ — $ 2,084 TVA and the U.S. Treasury, pursuant to the TVA Act, have entered into a memorandum of understanding under which the U.S. Treasury provides TVA with a $150 million credit facility. This credit facility was renewed for 2025 with a maturity date of September 30, 2025. Access to this credit facility or other similar financing arrangements with the U.S. Treasury has been available to TVA since the 1960s. TVA can borrow under the U.S. Treasury credit facility only if it cannot issue Bonds in the market on reasonable terms, and TVA considers the U.S. Treasury credit facility a secondary source of liquidity. The interest rate on any borrowing under this facility is based on the average rate on outstanding marketable obligations of the U.S. with maturities from date of issue of 12 months or less. There were no outstanding borrowings under the facility at September 30, 2024. The availability of this credit facility may be impacted by how the U.S. government addresses the possibility of approaching its debt limit.

Risk Management Activities and

Risk Management Activities and Derivative Transactions	12 Months Ended
	Sep. 30, 2024
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Risk Management Activities and Derivative Transactions	TVA is exposed to various risks related to commodity prices, investment prices, interest rates, currency exchange rates, and inflation as well as counterparty credit and performance risks. To help manage certain of these risks, TVA has historically entered into various derivative transactions, principally commodity option contracts, forward contracts, swaps, swaptions, futures, and options on futures. Overview of Accounting Treatment TVA recognizes certain of its derivative instruments as either assets or liabilities on its Consolidated Balance Sheets at fair value. The accounting for changes in the fair value of these instruments depends on (1) whether TVA uses regulatory accounting to defer the derivative gains and losses, (2) whether the derivative instrument has been designated and qualifies for hedge accounting treatment, and (3) if so, the type of hedge relationship (for example, cash flow hedge). The following tables summarize the accounting treatment that certain of TVA's financial derivative transactions receive: Summary of Derivative Instruments That Receive Hedge Accounting Treatment (part 1) Amount of Mark-to-Market Gain (Loss) Recognized in Accumulated Other Comprehensive Income (Loss) For the years ended September 30 (in millions) Derivatives in Cash Flow Hedging Relationship Objective of Hedge Transaction Accounting for Derivative 2024 2023 Currency swaps To protect against changes in cash flows caused by changes in foreign currency exchange rates (exchange rate risk) Unrealized gains and losses are recorded in AOCI and reclassified to Interest expense to the extent they are offset by gains and losses on the hedged transaction $ 25 $ 99 Summary of Derivative Instruments That Receive Hedge Accounting Treatment (part 2) (1) Amount of Gain (Loss) Reclassified from Accumulated Other Comprehensive Income (Loss) to Interest Expense For the years ended September 30 (in millions) Derivatives in Cash Flow Hedging Relationship 2024 2023 Currency swaps $ 48 $ 42 Note (1) There were no amounts excluded from effectiveness testing for any of the periods presented. Based on forecasted foreign currency exchange rates, TVA expects to reclassify approximately $1 million of gains from AOCI to Interest expense within the next 12 months to offset amounts anticipated to be recorded in Interest expense related to the forecasted exchange loss on the debt. Summary of Derivative Instruments That Do Not Receive Hedge Accounting Treatment Amount of Gain (Loss) Recognized in Income on Derivatives (1) For the years ended September 30 (in millions) Derivative Type Objective of Derivative Accounting for Derivative Instrument 2024 2023 Interest rate swaps To fix short-term debt variable rate to a fixed rate (interest rate risk) Mark-to-market gains and losses are recorded as regulatory liabilities and assets, respectively Realized gains and losses are recognized in Interest expense when incurred during the settlement period and are presented in operating cash flow $ (31) $ (45) Commodity derivatives To protect against fluctuations in market prices of purchased commodities (price risk) Mark-to-market gains and losses are recorded as regulatory liabilities and assets, respectively Realized gains and losses are recognized in Fuel expense or Purchased power expense as the contracts settle to match the delivery period of the underlying commodity (2) (295) (348) Notes (1) All of TVA's derivative instruments that do not receive hedge accounting treatment have unrealized gains (losses) that would otherwise be recognized in income but instead are deferred as regulatory liabilities and assets. As such, there were no related gains (losses) recognized in income for these unrealized gains (losses) for the years ended September 30, 2024 and 2023. (2) Of the amount recognized in 2024, $245 million and $50 million were reported in Fuel expense and Purchased power expense, respectively. Of the amount recognized in 2023, $301 million and $47 million were reported in Fuel expense and Purchased power expense, respectively. Fair Values of TVA Derivatives At September 30 (in millions) 2024 2023 Derivatives That Receive Hedge Accounting Treatment: Balance Balance Sheet Presentation Balance Balance Sheet Presentation Currency swaps £250 million Sterling $ (49) Accounts payable and accrued liabilities $(4); Other long-term liabilities $(45) $ (72) Accounts payable and accrued liabilities $(6); Other long-term liabilities $(66) £150 million Sterling (67) Accounts payable and accrued liabilities $(3); Other long-term liabilities $(64) (69) Accounts payable and accrued liabilities $(4); Other long-term liabilities $(65) Derivatives That Do Not Receive Hedge Accounting Treatment: Balance Balance Sheet Presentation Balance Balance Sheet Presentation Interest rate swaps $1.0 billion notional $ (622) Accounts payable and accrued liabilities $(10); Accrued interest $(26); Other long-term liabilities $(586) $ (499) Other current assets $1; Accrued interest $(27); Other long-term liabilities $(473) $476 million notional (218) Accounts payable and accrued liabilities $(3); Accrued interest $(9); Other long-term liabilities $(206) (159) Other current assets $3; Accrued interest $(8); Other long-term liabilities $(154) Commodity contract derivatives 2 Other current assets $5; Other long-term assets $2; Accounts payable and accrued liabilities $(3); Other long-term liabilities $(2) 31 Other current assets $21; Other long-term assets $12; Accounts payable and accrued liabilities $(1); Other long-term liabilities $(1) Commodity derivatives under the FHP (161) Accounts payable and accrued liabilities $(99); Other long-term liabilities $(62) (186) Accounts payable and accrued liabilities $(135); Other long-term liabilities $(51) Cash Flow Hedging Strategy for Currency Swaps To protect against exchange rate risk related to British pound sterling denominated Bond transactions, TVA entered into foreign currency hedges at the time the Bond transactions occurred. TVA had the following currency swaps outstanding at September 30, 2024: Currency Swaps Outstanding Effective Date of Currency Swap Contract Associated TVA Bond Issues Currency Exposure Expiration Date of Swap Overall Effective 2001 £250 million 2032 6.587% 2003 £150 million 2043 4.962% When the dollar strengthens against the British pound sterling, the exchange gain on the Bond liability and related accrued interest is offset by an equal amount of loss on the swap contract that is reclassified out of AOCI. Conversely, the exchange loss on the Bond liability and related accrued interest is offset by an equal amount of gain on the swap contract that is reclassified out of AOCI. All such exchange gains or losses on the Bond liability and related accrued interest are included in Long-term debt, net and Accrued interest, respectively. The offsetting exchange losses or gains on the swap contracts are recognized in AOCI. If any gain (loss) were to be incurred as a result of the early termination of the foreign currency swap contract, the resulting income (expense) would be amortized over the remaining life of the associated Bond as a component of Interest expense. The values of the currency swap liabilities are included in Accounts payable and accrued liabilities and Other long-term liabilities on the Consolidated Balance Sheets. Derivatives Not Receiving Hedge Accounting Treatment Interest Rate Derivatives . Generally TVA uses interest rate swaps to fix variable short-term debt to a fixed rate, and TVA uses regulatory accounting treatment to defer the MtM gains and losses on its interest rate swaps. The net deferred unrealized gains and losses are classified as regulatory liabilities or assets on TVA's Consolidated Balance Sheets and are included in the ratemaking formula when gains or losses are realized. The values of these derivatives are included in Other current assets, Accounts payable and accrued liabilities, Accrued interest, and Other long-term liabilities on the Consolidated Balance Sheets, and realized gains and losses, if any, are included on TVA's Consolidated Statements of Operations. For the years ended September 30, 2024 and 2023, the changes in fair market value of the interest rate swaps resulted in the increase in unrealized losses of $182 million and the reduction in unrealized losses of $240 million, respectively. TVA may hold short-term debt balances lower than the notional amount of the interest rate swaps from time to time due to changes in business conditions and other factors. While actual balances vary, TVA generally plans to maintain average balances of short-term debt equal to or in excess of the combined notional amount of the interest rate swaps. Commodity Derivatives . TVA enters into certain derivative contracts for natural gas that require physical delivery of the contracted quantity of the commodity. TVA may also enter into short-term PPAs with a term of less than one year that provide an option to financially settle contracted power deliveries. This option creates an embedded derivative in the hosting power purchase agreement. TVA marks to market these contracts and defers the unrealized gains (losses) as regulatory liabilities (assets). At September 30, 2024, TVA's natural gas contract derivatives had terms of up to four years. Commodity Contract Derivatives At September 30 2024 2023 Number of Contracts Notional Amount Fair Value (MtM) Number of Contracts Notional Amount Fair Value ( MtM ) (in millions) Natural gas contract derivatives 45 321 million mmBtu $ 2 54 318 million mmBtu $ 31 Commodity Derivatives under the FHP. Currently, TVA is hedging exposure to the price of natural gas under the FHP. There is no Value at Risk aggregate transaction limit under the current FHP structure, but the TVA Board reviews and authorizes the use of tolerances and measures annually. TVA's FHP policy prohibits trading financial instruments under the FHP for speculative purposes. At September 30, 2024, TVA's natural gas swap contracts under the FHP had remaining terms of up to four years. Commodity Derivatives under Financial Hedging Program (1) At September 30 2024 2023 Number of Contracts Notional Amount Fair Value (MtM) (in millions) Number of Contracts Notional Amount Fair Value (MtM) (in millions) Natural gas swap contracts 126 230 million mmBtu $ (161) 221 388 million mmBtu $ (186) Note (1) Fair value amounts presented are based on the net commodity position with the counterparty. Notional amounts disclosed represent the net value of contractual amounts. TVA defers all FHP unrealized gains (losses) as regulatory liabilities (assets) and records the realized gains or losses in Fuel expense and Purchased power expense to match the delivery period of the underlying commodity. Offsetting of Derivative Assets and Liabilities The amounts of TVA's derivative instruments as reported on the Consolidated Balance Sheets are shown in the table below: Derivative Assets and Liabilities (1) At September 30 (in millions) 2024 2023 Assets Interest rate swaps $ — $ 4 Commodity contract derivatives 7 33 Commodity derivatives under the FHP (2) — — Total derivatives subject to master netting or similar arrangement $ 7 $ 37 Liabilities Currency swaps $ 116 $ 141 Interest rate swaps (3) 840 662 Commodity contract derivatives 5 2 Commodity derivatives under the FHP (2) 161 186 Total derivatives subject to master netting or similar arrangement $ 1,122 $ 991 Notes (1) Offsetting amounts include counterparty netting of derivative contracts. Except as discussed below, there were no other material offsetting amounts on TVA's Consolidated Balance Sheets at either September 30, 2024 or 2023. (2) At September 30, 2024, the gross derivative asset and gross derivative liability was $4 million and $165 million, respectively, with offsetting amounts for each totaling $4 million. At September 30, 2023, the gross derivative asset and gross derivative liability were $26 million and $212 million, respectively, with offsetting amounts for each totaling $26 million. (3) Letters of credit of approximately $535 million and $509 million were posted as collateral at September 30, 2024 and 2023, respectively, to partially secure the liability positions of one of the interest rate swaps in accordance with the collateral requirements for this derivative. Other Derivative Instruments Investment Fund Derivatives . Investment funds consist primarily of funds held in the NDT, ART, SERP, DCP, and RP. See Note 16 — Fair Value Measurements — Investment Funds for a discussion of the trusts, plans, and types of investments. The NDT and ART may invest in derivative instruments which may include swaps, futures, options, forwards, and other instruments. At September 30, 2024 and 2023, the NDT held investments in forward contracts to purchase debt securities. The fair values of these derivatives were in net asset positions totaling $11 million at both September 30, 2024 and 2023. Collateral . TVA's interest rate swaps, currency swaps, and commodity derivatives under the FHP contain contract provisions that require a party to post collateral (in a form such as cash or a letter of credit) when the party's liability balance under the agreement exceeds a certain threshold. At September 30, 2024, the aggregate fair value of all derivative instruments with credit-risk related contingent features that were in a liability position was $1.1 billion. TVA's collateral obligations at September 30, 2024, under these arrangements were $552 million, for which TVA had posted $535 million in letters of credit. These letters of credit reduce the available balance under the related credit facilities. TVA's assessment of the risk of its nonperformance includes a reduction in its exposure under the interest rate swap contracts as a result of this posted collateral. For all of its derivative instruments with credit-risk related contingent features: • If TVA remains a majority-owned U.S. government entity but S&P Global Ratings ("S&P") or Moody's Investors Service, Inc. ("Moody's") downgrades TVA's credit rating to AA or Aa2, respectively, TVA's collateral obligations would likely increase by $22 million, and • If TVA ceases to be majority-owned by the U.S. government, TVA's credit rating would likely be downgraded and TVA would be required to post additional collateral. Counterparty Risk TVA may be exposed to certain risks when a counterparty has the potential to fail to meet its obligations in accordance with agreed terms. These risks may be related to credit, operational, or nonperformance matters. To mitigate certain counterparty risk, TVA analyzes the counterparty's financial condition prior to entering into an agreement, establishes credit limits, monitors the appropriateness of those limits, as well as any changes in the creditworthiness of the counterparty, on an ongoing basis, and when required, employs credit mitigation measures, such as collateral or prepayment arrangements and master purchase and sale agreements. Customers . TVA is exposed to counterparty credit risk associated with trade accounts receivable from delivered power sales to LPCs, and from industries and federal agencies directly served, all located in the Tennessee Valley region. Of the $1.7 billion and $1.6 billion of receivables from power sales outstanding at September 30, 2024 and 2023, respectively, nearly all of the counterparties were rated investment grade. The majority of the obligations of these customers that are not investment grade are secured by collateral. TVA is also exposed to risk from exchange power arrangements with a small number of investor-owned regional utilities related to either delivered power or the replacement of open positions of longer-term purchased power or fuel agreements. TVA believes its policies and procedures for counterparty performance risk reviews have generally protected TVA against significant exposure related to market and economic conditions. See Note 1 — Summary of Significant Accounting Policies — Allowance for Uncollectible Accounts, Note 3 — Accounts Receivable, Net , and Note 9 — Other Long-Term Assets . TVA had revenue from two LPCs that collectively accounted for 17 percent of total operating revenues for both the years ended September 30, 2024 and 2023. Suppliers. TVA assesses potential supplier performance risks, including procurement of fuel, purchased power, parts, and services. If suppliers are unable to perform under TVA's existing contracts or if TVA is unable to obtain similar services or supplies from other vendors, TVA could experience delays, disruptions, additional costs, or other operational outcomes that may impact generation, maintenance, and capital programs. If certain fuel or purchased power suppliers fail to perform under the terms of their contract with TVA, TVA might lose the money that it paid to the supplier under the contract and have to purchase replacement fuel or power on the spot market, perhaps at a significantly higher price than TVA was entitled to pay under the contract. In addition, TVA might not be able to acquire replacement fuel or power in a timely manner and thus might be unable to satisfy its own obligations to deliver power. TVA continues evaluating potential supplier performance risks and supplier impact but cannot determine or predict the duration of such risks/impacts or the extent to which such risks/impacts could affect TVA's business, operations, and financial results or cause potential business disruptions. TVA continues to experience impacts due to inflation, supply chain material challenges, and labor availability. This has led to project delays, limited availability, and/or price increases for supplies and labor. TVA has been able to manage these challenges with limited business disruptions at this time; however, should pressures continue long term, TVA could experience more significant disruptions and pressure to further increase power rates. Natural Gas and Fuel Oil . TVA purchases a significant amount of its natural gas requirements through contracts with a variety of suppliers and purchases substantially all of its fuel oil requirements on the spot market. TVA delivers to its gas fleet under firm and non-firm transportation contracts on multiple interstate natural gas pipelines. TVA contracts for storage capacity that allows for operational flexibility and increased supply during peak gas demand scenarios or supply disruptions. TVA uses contracts of various lengths and terms to meet the projected natural gas needs of its natural gas fleet. TVA also maintains on-site, fuel oil backup to operate at the majority of the combustion turbine sites in the event of major supply disruptions. In the event a supplier experiences an incident that limits its ability to fulfill its firm contractual obligations to supply TVA with natural gas, TVA intends to leverage its storage and balancing services and/or replace the volume with a third party to ensure reliability of generation. Coal . To help ensure a reliable supply of coal, TVA had coal contracts with multiple suppliers at September 30, 2024. The contracted supply of coal is sourced from several geographic regions of the U.S. and is delivered via barge and rail. As a result of emerging technologies, environmental regulations, industry trends, and natural gas market volatility over the past few years, coal suppliers are facing increased financial pressure, which has led to relatively poor credit ratings and bankruptcies, restructuring, mine closures, or other scenarios. A long-term continued decline in demand for coal could result in more consolidations, additional bankruptcies, restructuring, mine closures, or other scenarios. Nuclear Fuel . Nuclear fuel is obtained predominantly through long-term uranium concentrate supply contracts, contracted conversion services, contracted enrichment services, or a combination thereof, and contracted fuel fabrication services. The supply markets for uranium concentrates and certain nuclear fuel services are subject to price fluctuations and availability restrictions. Supply market conditions may make procurement contracts subject to credit risk related to the potential nonperformance of counterparties. In the event of nonperformance by these or other suppliers, TVA believes that replacement uranium concentrate and nuclear fuel services can be obtained, although at prices that may be unfavorable when compared to the prices under the current supply agreements. Purchased Power . TVA acquires power from a variety of power producers through long-term and short-term PPAs as well as through spot market purchases. Because of the reliability risk of purchased power, TVA requires that the PPAs contain certain counterparty performance assurance requirements to help insure counterparty performance during the term of the agreements. Other Suppliers . Mounting solar supply chain constraints, commodity price increases, and the trade policy investigation into solar panel imports have created challenges for the U.S. solar industry. TVA's existing solar PPA portfolio is not immune from these challenges. Similar to the experience of the rest of the industry, the majority of TVA's contracted PPAs from previous requests for proposals ("RFPs") that are not yet online have been impacted by project delays and price increases. Derivative Counterparties

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Sep. 30, 2024
Fair Value Disclosures [Abstract]
Fair Value Measurements	16. Fair Value Measurements Fair value is determined based on the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the asset or liability's principal market, or in the absence of a principal market, the most advantageous market for the asset or liability in an orderly transaction between market participants. TVA uses market or observable inputs as the preferred source of values, followed by assumptions based on hypothetical transactions in the absence of market inputs. Valuation Techniques The measurement of fair value results in classification into a hierarchy by the inputs used to determine the fair value as follows: Level 1 — Unadjusted quoted prices in active markets accessible by the reporting entity for identical assets or liabilities. Active markets are those in which transactions for the asset or liability occur with sufficient frequency and volume to provide pricing. Level 2 — Pricing inputs other than quoted market prices included in Level 1 that are based on observable market data and that are directly or indirectly observable for substantially the full term of the asset or liability. These include quoted market prices for similar assets or liabilities, quoted market prices for identical or similar assets in markets that are not active, adjusted quoted market prices, inputs from observable data such as interest rate and yield curves, volatilities and default rates observable at commonly quoted intervals, and inputs derived from observable market data by correlation or other means. Level 3 — Pricing inputs that are unobservable, or less observable, from objective sources. Unobservable inputs are only to be used to the extent observable inputs are not available. These inputs maintain the concept of an exit price from the perspective of a market participant and should reflect assumptions of other market participants. An entity should consider all market participant assumptions that are available without unreasonable cost and effort. These are given the lowest priority and are generally used in internally developed methodologies to generate management's best estimate of the fair value when no observable market data is available. A financial instrument's level within the fair value hierarchy (where Level 1 is the highest and Level 3 is the lowest) is based on the lowest level of input significant to the fair value measurement. The following sections describe the valuation methodologies TVA uses to measure different financial instruments at fair value. Except for gains and losses on SERP, DCP, and RP assets, all changes in fair value of these assets and liabilities have been recorded as changes in regulatory assets, regulatory liabilities, or AOCI on TVA's Consolidated Balance Sheets and Consolidated Statements of Comprehensive Income (Loss). Except for gains and losses on SERP and DCP assets, there has been no impact to the Consolidated Statements of Operations or the Consolidated Statements of Cash Flows related to these fair value measurements. Investment Funds At September 30, 2024, Investment funds were comprised of $5.0 billion of equity securities and debt securities classified as trading measured at fair value. Equity and trading debt securities are held in the NDT, ART, SERP, DCP, and RP. The NDT holds funds for the ultimate decommissioning of TVA's nuclear power plants. The ART holds funds primarily for the costs related to the future closure and retirement of TVA's other long-lived assets. The balances in the NDT and ART were $3.3 billion and $1.5 billion, respectively, at September 30, 2024. TVA established a SERP to provide benefits to selected employees of TVA which are comparable to those provided by competing organizations. The DCP is designed to provide participants with the ability to defer compensation to future periods. The RP is a non-qualified excess 401(k) plan designed to allow certain eligible employees whose contributions to the 401(k) plan are limited by Internal Revenue Service ("IRS") rules to save additional amounts for retirement and receive non-elective and matching employer contributions. The NDT, ART, SERP, DCP, and RP funds are invested in portfolios of securities generally designed to achieve a return in line with overall equity and debt market performance. The NDT, ART, SERP, DCP, and RP are composed of multiple types of investments and are managed by external institutional investment managers. Most U.S. and international equities, U.S. Treasury inflation-protected securities ("TIPS"), and real estate investment trust securities, and certain derivative instruments are measured based on quoted exchange prices in active markets and are classified as Level 1 valuations. Fixed-income investments, high-yield fixed-income investments, currencies, and most derivative instruments are non-exchange traded and are classified as Level 2 valuations. These measurements are based on market and income approaches with observable market inputs. Cash equivalents and other short-term investments are highly liquid securities with maturities of less than three months and 12 months, respectively. These consist primarily of discount securities such as repurchase agreements and U.S. Treasury bills. These securities may be priced at cost, which approximates fair value due to the short-term nature of the instruments. These securities are classified as Level 2. Active market pricing may be utilized for U.S. Treasury bills, which are classified as Level 1. Private equity limited partnerships, private real asset investments, and private credit investments may include holdings of investments in private real estate, venture capital, buyout, mezzanine or subordinated debt, restructuring or distressed debt, and special situations through funds managed by third-party investment managers. These investments generally involve a three-to-four-year period where the investor contributes capital, followed by a period of distribution, typically over several years. The investment period is generally, at a minimum, 10 years or longer. The NDT had unfunded commitments related to private equity limited partnerships of $382 million, private real assets of $120 million, and private credit of $87 million at September 30, 2024. The ART had unfunded commitments related to limited partnerships in private equity of $152 million, private real assets of $61 million, and private credit of $46 million at September 30, 2024. These investments have no redemption or limited redemption options and may also impose restrictions on the NDT's and ART's ability to liquidate their investments. There are no readily available quoted exchange prices for these investments. The fair value of these investments is based on information provided by the investment managers. These investments are valued on a quarterly basis. TVA's private equity limited partnerships, private real asset investments, and private credit investments are valued at net asset values ("NAV") as a practical expedient for fair value. TVA classifies its interest in these types of investments as investments measured at NAV in the fair value hierarchy. Commingled funds represent investment funds comprising multiple individual financial instruments. The commingled funds held by the NDT, ART, SERP, DCP, and RP consist of either a single class of securities, such as equity, debt, or foreign currency securities, or multiple classes of securities. All underlying positions in these commingled funds are either exchange traded or measured using observable inputs for similar instruments. The fair value of commingled funds is based on NAV per fund share (the unit of account), derived from the prices of the underlying securities in the funds. These commingled funds can be redeemed at the measurement date NAV and are classified as Commingled funds measured at NAV in the fair value hierarchy. Realized and unrealized gains and losses on equity and trading debt securities are recognized in current earnings and are based on average cost. The gains and losses of the NDT and ART are subsequently reclassified to a regulatory asset or liability account in accordance with TVA's regulatory accounting policy. See Note 1 — Summary of Significant Accounting Policies — Cost-Based Regulation and Note 10 — Regulatory Assets and Liabilities . TVA recorded unrealized gains and losses related to its equity and trading debt securities held during each period as follows: Unrealized Investment Gains (Losses) (1) For the years ended September 30 (in millions) Fund Financial Statement Presentation 2024 2023 NDT Regulatory assets (2) $ 324 $ 162 ART Regulatory assets (3) 171 96 SERP Other income (expense) 14 6 DCP Other income (expense) 2 1 Notes (1) The unrealized losses for the RP were less than $1 million for both the years ended September 30, 2024 and 2023 and therefore were not represented in the table above. (2) Includes $93 million of unrealized gains and $27 million of unrealized gains related to NDT equity securities (excluding commingled funds) for the years ended September 30, 2024 and 2023, respectively. (3) Includes $36 million of unrealized gains and $13 million of unrealized gains related to ART equity securities (excluding commingled funds) for the years ended September 30, 2024 and 2023, respectively. Currency and Interest Rate Swap Derivatives See Note 15 — Risk Management Activities and Derivative Transactions — Cash Flow Hedging Strategy for Currency Swaps and Derivatives Not Receiving Hedge Accounting Treatment for a discussion of the nature, purpose, and contingent features of TVA's currency swaps and interest rate swaps. These swaps are classified as Level 2 valuations and are valued based on income approaches using observable market inputs for similar instruments. Commodity Contract Derivatives and Commodity Derivatives under the FHP Commodity Contract Derivatives. Most of these derivative contracts are valued based on market approaches, which utilize short-term and mid-term market-quoted prices from an external industry brokerage service. These contracts are classified as Level 2 valuations. Commodity Derivatives under the FHP. Swap contracts are valued using a pricing model based on New York Mercantile Exchange inputs and are subject to nonperformance risk outside of the exit price. These contracts are classified as Level 2 valuations. See Note 15 — Risk Management Activities and Derivative Transactions — Derivatives Not Receiving Hedge Accounting Treatment — Commodity Derivatives and — Commodity Derivatives under the FHP . Nonperformance Risk The assessment of nonperformance risk, which includes credit risk, considers changes in current market conditions, readily available information on nonperformance risk, letters of credit, collateral, other arrangements available, and the nature of master netting arrangements. TVA is a counterparty to currency swaps, interest rate swaps, commodity contracts, and other derivatives which subject TVA to nonperformance risk. Nonperformance risk on the majority of investments and certain exchange-traded instruments held by TVA is incorporated into the exit price that is derived from quoted market data that is used to mark the investment to market. Nonperformance risk for most of TVA's derivative instruments is an adjustment to the initial asset/liability fair value. TVA adjusts for nonperformance risk, both of TVA (for liabilities) and the counterparty (for assets), by applying credit valuation adjustments ("CVAs"). TVA determines an appropriate CVA for each applicable financial instrument based on the term of the instrument and TVA's or the counterparty's credit rating as obtained from Moody's. For companies that do not have an observable credit rating, TVA uses internal analysis to assign a comparable rating to the counterparty. TVA discounts each financial instrument using the historical default rate (as reported by Moody's for CY 1983 to CY 2023) for companies with a similar credit rating over a time period consistent with the remaining term of the contract. The application of CVAs resulted in a less than $1 million decrease in the fair value of assets and a $1 million decrease in the fair value of liabilities at September 30, 2024. Fair Value Measurements The following tables set forth by level, within the fair value hierarchy, TVA's financial assets and liabilities that were measured at fair value on a recurring basis at September 30, 2024 and 2023. Financial assets and liabilities have been classified in their entirety based on the lowest level of input that is significant to the fair value measurement. TVA's assessment of the significance of a particular input to the fair value measurement requires judgment and may affect the determination of the fair value of the assets and liabilities and their classification in the fair value hierarchy levels. Fair Value Measurements At September 30, 2024 (in millions) Quoted Prices in Active Significant Other Significant Total Assets Investments Equity securities $ 770 $ — $ — $ 770 Government debt securities (1)(2) 400 57 — 457 Corporate debt securities (4) — 378 — 378 Mortgage and asset-backed securities — 43 — 43 Institutional mutual funds 342 — — 342 Forward debt securities contracts — 11 — 11 Cash equivalents and other short-term investments (2)(3) 95 183 — 278 Private equity funds measured at net asset value (5) — — — 738 Private real asset funds measured at net asset value (5) — — — 432 Private credit funds measured at net asset value (5) — — — 219 Commingled funds measured at net asset value (5) — — — 1,300 Total investments 1,607 672 — 4,968 Interest rate swaps — — — — Commodity contract derivatives — 7 — 7 Total $ 1,607 $ 679 $ — $ 4,975 Quoted Prices in Active Markets for Identical Liabilities Significant Other Significant Total Liabilities Currency swaps (6) $ — $ 116 $ — $ 116 Interest rate swaps — 840 — 840 Commodity contract derivatives — 5 — 5 Commodity derivatives under the FHP — 161 — 161 Total $ — $ 1,122 $ — $ 1,122 Notes (1) Includes obligations of government-sponsored entities. (2) There are $400 million of U.S. Treasury securities in Level 1 Government debt securities and $95 million of U.S. Treasury securities in Level 1 Cash equivalents and other short-term investments for a total of $495 million of U.S. Treasury securities within Level 1 of the fair value hierarchy. (3) Includes $78 million net payables (interest receivable, dividends receivable, receivables for investments sold, and payables for investments purchased), and $174 million of repurchase agreements in Level 2 Cash equivalents and other short-term investments. (4) Includes both U.S. and foreign debt. (5) Certain investments that are measured at fair value using the NAV or its equivalent (alternative investments) have not been categorized in the fair value hierarchy. The inputs to these fair value measurements include underlying NAVs, discounted cash flow valuations, comparable market valuations, estimated benchmark yields, and adjustments for currency, credit, liquidity, and other risks. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the amounts presented on the Consolidated Balance Sheets. (6) TVA records currency swaps net of cash collateral received from or paid to the counterparty, to the extent such amount is not recorded in Accounts payable and accrued liabilities. See Note 15 — Risk Management Activities and Derivative Transactions — Offsetting of Derivative Assets and Liabilities . Fair Value Measurements At September 30, 2023 (in millions) Quoted Prices in Active Significant Other Significant Total Assets Investments Equity securities $ 608 $ — $ — $ 608 Government debt securities (1)(2) 287 60 — 347 Corporate debt securities (4) — 300 — 300 Mortgage and asset-backed securities — 36 — 36 Institutional mutual funds 288 — — 288 Forward debt securities contracts — 11 — 11 Cash equivalents and other short-term investments (2)(3) 104 166 — 270 Private equity funds measured at net asset value (5) — — — 583 Private real asset funds measured at net asset value (5) — — — 387 Private credit funds measured at net asset value (5) — — — 158 Commingled funds measured at net asset value (5) — — — 1,135 Total investments 1,287 573 — 4,123 Interest rate swaps — 4 — 4 Commodity contract derivatives — 33 — 33 Total $ 1,287 $ 610 $ — $ 4,160 Quoted Prices in Active Markets for Identical Liabilities Significant Other Significant Total Liabilities Currency swaps (6) $ — $ 141 $ — $ 141 Interest rate swaps — 662 — 662 Commodity contract derivatives — 2 — 2 Commodity derivatives under the FHP — 186 — 186 Total $ — $ 991 $ — $ 991 Notes (1) Includes obligations of government-sponsored entities. (2) There are $287 million of U.S. Treasury securities in Level 1 Government debt securities and $104 million of U.S. Treasury securities in Level 1 Cash equivalents and other short-term investments for a total of $391 million of U.S. Treasury securities within Level 1 of the fair value hierarchy. (3) Includes $73 million net payables (interest receivable, dividends receivable, receivables for investments sold, and payables for investments purchased). (4) Includes both U.S. and foreign debt. (5) Certain investments that are measured at fair value using the NAV or its equivalent (alternative investments) have not been categorized in the fair value hierarchy. The inputs to these fair value measurements include underlying NAVs, discounted cash flow valuations, comparable market valuations, estimated benchmark yields, and adjustments for currency, credit, liquidity, and other risks. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the amounts presented on the Consolidated Balance Sheets. (6) TVA records currency swaps net of cash collateral received from or paid to the counterparty, to the extent such amount is not recorded in Accounts payable and accrued liabilities. See Note 15 — Risk Management Activities and Derivative Transactions — Offsetting of Derivative Assets and Liabilities . Other Financial Instruments Not Recorded at Fair Value TVA uses the methods and assumptions described below to estimate the fair value of each significant class of financial instruments. The fair value of the financial instruments held at September 30, 2024 and 2023, may not be representative of the actual gains or losses that will be recorded when these instruments mature or are called or presented for early redemption. The estimated values of TVA's financial instruments not recorded at fair value at September 30, 2024 and 2023, were as follows: Estimated Values of Financial Instruments Not Recorded at Fair Value (in millions) At September 30, 2024 At September 30, 2023 Valuation Classification Carrying Fair Carrying Fair EnergyRight ® receivables, net (including current portion) Level 2 $ 56 $ 56 $ 59 $ 55 Loans and other long-term receivables, net (including current portion) Level 2 105 99 104 96 EnergyRight ® financing obligations (including current portion) Level 2 66 74 69 81 Unfunded loan commitments Level 2 — — — 1 Membership interests of VIEs subject to mandatory redemption (including current portion) Level 2 17 19 18 19 Long-term outstanding power bonds, net (including current maturities) Level 2 18,889 19,416 18,866 17,963 Long-term debt of VIEs, net (including current maturities) Level 2 934 966 968 927 The carrying values of Cash and cash equivalents, Restricted cash and cash equivalents, Accounts receivable, net, and Short-term debt, net approximate their fair values. The fair value for loans and other long-term receivables is estimated by determining the present value of future cash flows using a discount rate equal to lending rates for similar loans made to borrowers with similar credit ratings and for similar remaining maturities, where applicable. The fair value of long-term debt and membership interests of VIEs subject to mandatory redemption is estimated by determining the present value of future cash flows using current market rates for similar obligations, giving effect to credit ratings and remaining maturities.

Other Income (Expense), Net

Other Income (Expense), Net	12 Months Ended
	Sep. 30, 2024
Other Income and Expenses [Abstract]
Other Income (Expense), Net	18. Other Income, Net Income and expenses not related to TVA's operating activities are summarized in the following table: Other Income, Net For the years ended September 30 (in millions) 2024 2023 2022 Interest income $ 42 $ 34 $ 15 External services 17 15 16 Gains (losses) on investments 23 13 (17) Miscellaneous (11) (1) (7) Total other income, net $ 71 $ 61 $ 7

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Sep. 30, 2024
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	22. Commitments and Contingencies Commitments Power Purchase Obligations. TVA has contracted with various independent power producers and LPCs for additional capacity to be made available to TVA. Several of these agreements have contractual minimum payments and are accounted for as either finance or operating leases. In total, these agreements provide 4,487 megawatts ("MW") of summer net capability. The remaining terms of the agreements range up to 11 years. Additionally, TVA has contracted with regional transmission organizations to reserve 4,750 MW of transmission service to support purchases from the market and wind PPAs. The remaining terms of these agreements range up to five years. TVA has recorded $519 million, $355 million, and $366 million of expense under these power purchase and transmission service agreements during 2024, 2023, and 2022, respectively. TVA has one power purchase agreement that was negotiated as part of arranging financing for the facility. At September 30, 2024, the non-lease portion of the commitment for each of the next five years and thereafter is shown below: 2025 2026 2027 2028 2029 Thereafter Unconditional purchase obligation $ 166 $ 166 $ 166 $ 165 $ 166 $ 413 Under federal law, TVA is obligated to purchase power from qualifying facilities (cogenerators and small power producers). As of September 30, 2024, there was a combined qualifying facility capacity of 279 MW from 1,197 different generation sources, from which TVA purchased power under this law. Unfunded Loan Commitments . At September 30, 2024, TVA had no commitments under unfunded loan commitments for 2025 through 2029. Other Commitments. See Note 8 — Leases , Note 11 — Variable Interest Entities , Note 14 — Debt and Other Obligations , and Note 20 — Benefit Plans for the obligations and commitments attributable to leases, VIEs and membership interests of VIEs subject to mandatory redemption, leaseback obligations, and the retirement plan, respectively. Contingencies Nuclear Insurance . Section 170 of the Atomic Energy Act, commonly known as the Price-Anderson Act, provides a layered framework of financial protection to compensate for liability claims of members of the public for personal injury and property damages arising from a nuclear incident in the U.S. This financial protection consists of two layers of coverage. The primary level is private insurance underwritten by American Nuclear Insurers and provides public liability insurance coverage of $500 million for each nuclear power plant licensed to operate. If this amount is not sufficient to cover claims arising from a nuclear incident, the second level, Secondary Financial Protection, applies. Within the Secondary Financial Protection level, the licensee of each nuclear reactor has a contingent obligation to pay a retrospective premium, equal to its proportionate share of the loss in excess of the primary level, regardless of proximity to the incident of fault, up to a maximum of $166 million per reactor per incident. With TVA's seven reactors, the maximum total contingent obligation per incident is $1.2 billion. This retrospective premium is payable at a maximum rate currently set at $25 million per year per nuclear incident per reactor. Currently, 95 reactors are participating in the Secondary Financial Protection program. In the event that a nuclear incident results in public liability claims, the primary level provided by American Nuclear Insurers combined with the Secondary Financial Protection should provide up to $16.3 billion in coverage. Federal law requires that each NRC power reactor licensee obtain property insurance from private sources to cover the cost of stabilizing and decontaminating a reactor and its station site after an accident. TVA carries property, decommissioning liability, and decontamination liability insurance from Nuclear Electric Insurance Limited ("NEIL") and European Mutual Association for Nuclear Insurance. The limits available for a loss are up to $2.1 billion for two of TVA's nuclear sites and up to $2.8 billion for the remaining site. Some of this insurance may require the payment of retrospective premiums up to a maximum of $114 million. TVA purchases accidental outage (business interruption) insurance for TVA's nuclear sites from NEIL. In the event that an accident covered by this policy takes a nuclear unit offline or keeps a nuclear unit offline, NEIL will pay TVA, after a waiting period, an indemnity (a set dollar amount per week) with a maximum indemnity of $490 million per unit. This insurance policy may require the payment of retrospective premiums up to a maximum of $44 million, but only to the extent the retrospective premium is deemed necessary by the NEIL Board of Directors to pay losses unable to be covered by NEIL's surplus. Decommissioning Costs. TVA recognizes legal obligations associated with the future retirement of certain tangible long-lived assets related primarily to nuclear generating plants, coal-fired generating plants, hydroelectric generating plants/dams, transmission structures, and other property-related assets. See Note 13 — Asset Retirement Obligations . Nuclear Decommissioning . Provision for decommissioning costs of nuclear generating units is based on options prescribed by the NRC procedures to dismantle and decontaminate the facilities to meet the NRC criteria for license termination. At September 30, 2024, $3.8 billion, representing the discounted value of future estimated nuclear decommissioning costs, was included in nuclear AROs. The actual decommissioning costs may vary from the derived estimates because of, among other things, changes in current assumptions, such as the assumed dates of decommissioning, changes in regulatory requirements, changes in technology, and changes in the cost of labor, materials, and equipment. Utilities that own and operate nuclear plants are required to use different procedures in calculating nuclear decommissioning costs under GAAP than those that are used in calculating nuclear decommissioning costs when reporting to the NRC. The two sets of procedures produce different estimates for the costs of decommissioning primarily because of differences in the underlying assumptions. TVA bases its nuclear decommissioning estimates on site-specific cost studies. The most recent study was approved and implemented in September 2022. Site-specific cost studies are updated for each of TVA's nuclear units at least every five years. TVA maintains an NDT to provide funding for the ultimate decommissioning of its nuclear power plants. See Note 16 — Fair Value Measurements — Investment Funds . TVA monitors the value of its NDT and believes that, over the long term and before cessation of nuclear plant operations and commencement of decommissioning activities, adequate funds from investments and additional contributions, if necessary, will be available to support decommissioning. TVA's operating nuclear power units are licensed through various dates between 2033 - 2055, depending on the unit. It may be possible to extend the operating life of some of the units with approval from the NRC. See Note 10 — Regulatory Assets and Liabilities — Nuclear Decommissioning Costs and Note 13 — Asset Retirement Obligations . Non-Nuclear Decommissioning . At September 30, 2024, $7.0 billion, representing the discounted value of future estimated non-nuclear decommissioning costs, was included in non-nuclear AROs. This decommissioning cost estimate involves estimating the amount and timing of future expenditures and making judgments concerning whether or not such costs are considered a legal obligation. Estimating the amount and timing of future expenditures includes, among other things, making projections of the timing and duration of the asset retirement process and how costs will escalate with inflation. The actual decommissioning costs may vary from the derived estimates because of changes in current assumptions, such as the assumed dates of decommissioning, changes in regulatory requirements, changes in technology, and changes in the cost of labor, materials, and equipment. TVA updates its underlying assumptions for non-nuclear decommissioning AROs at least every five years. However, material changes in underlying assumptions that impact the amount and timing of undiscounted cash flows are continuously monitored and incorporated into ARO balances in the period identified. TVA maintains an ART to help fund the ultimate decommissioning of its non-nuclear power assets. See Note 16 — Fair Value Measurements — Investment Funds . Estimates involved in determining if additional funding will be made to the ART include inflation rate, rate of return projections on the fund investments, and the planned use of other sources to fund decommissioning costs. See Note 10 — Regulatory Assets and Liabilities — Non-Nuclear Decommissioning Costs and Note 13 — Asset Retirement Obligations . Environmental Matters. TVA's generation activities, like those across the utility industry and in other industrial sectors, are subject to federal, state, and local environmental laws and regulations. Major areas of regulation affecting TVA's activities include air quality control, greenhouse gas ("GHG") emissions, water quality control, and management and disposal of solid and hazardous wastes. Regulations in these major areas continue to become more stringent and have, and will continue to have, a particular emphasis on climate change, renewable generation, and energy efficiency. TVA has incurred, and expects to continue to incur, substantial capital and operating and maintenance costs to comply with evolving environmental requirements primarily associated with, but not limited to, the operation of TVA's coal-fired and natural gas-fired generating units in general and emissions of pollutants from those units. Environmental requirements placed on the operation of coal-fired and other generating units using fossil fuels such as oil and natural gas will likely continue to become more restrictive over time. Failure to comply with environmental and safety requirements can result in enforcement actions and litigation, which can lead to the imposition of significant civil liability, including fines and penalties, criminal sanctions, and/or temporary or permanent closure of non-compliant facilities. Historical non-compliance can also lead to difficulty in renewing existing permits, as well as difficulty in obtaining permits to bring new generation facilities online. Other obstacles to renewal or permitting of new facilities include a proliferation of non-government organizations seeking to use litigation tools to delay or stop altogether permitting of new fossil fuel facilities in favor of renewable energy projects . Compliance with the 2015 CCR Rule required implementation of a groundwater monitoring program, additional engineering, evaluation of authorized closure methods, coordination with certain state authorities, and ongoing analysis at each TVA CCR unit. As further analyses are performed, including evaluation of monitoring results, there is the potential for additional costs for investigation and/or remediation. In addition, on May 8, 2024, EPA published its Legacy CCR Rule, which expands the scope of the existing regulatory requirements of the 2015 CCR Rule to include two additional classes of CCR units: Legacy SIs and CCRMUs. See Note 13 — Asset Retirement Obligations . In May 2024, EPA also published (1) a final rule that establishes more stringent technology-based effluent limitations for four waste streams from coal-fired plants, (2) a rule that strengthens and updates the Mercury and Air Toxics Standards for electric generating units to reflect recent developments in control technologies, and (3) a rule that establishes GHG emission guidelines for existing coal-fired plants and GHG performance standards for new natural gas-fired power plants. These rules are all subject to legal challenges, and if the challenges are not successful, TVA would incur substantial costs to comply with the rules. Liability for releases, natural resource damages, and required cleanup of hazardous substances is primarily regulated by the federal Comprehensive Environmental Response, Compensation, and Liability Act ("CERCLA"), the Resource Conservation and Recovery Act ("RCRA"), and other federal and parallel state statutes. In a manner similar to many other governmental entities, industries, and power systems, TVA has generated or used hazardous substances over the years. TVA operations at some facilities have resulted in releases of contaminants that TVA has addressed or is addressing consistent with state and federal requirements. At September 30, 2024 and 2023, TVA's estimated liability for required cleanup and similar environmental work for those sites for which sufficient information is available to develop a cost estimate was $15 million and $16 million, respectively, on a non-discounted basis, and was included in Accounts payable and accrued liabilities and Other long- term liabilities on the Consolidated Balance Sheets. Additionally, the potential inclusion of new hazardous substances under CERCLA and RCRA jurisdiction could significantly affect TVA's future liability for remediating historical releases. In August 2015, Tennessee Department of Environment and Conservation ("TDEC") issued an order that includes an iterative process through which TVA and TDEC will identify and evaluate any CCR contamination risks and, if necessary, respond to such risks. TVA is also following a similar process pursuant to a consent order. At September 30, 2024, TVA's estimated liability for costs associated with environmental remediation activities for the sites covered by these orders for which sufficient information is available to develop a cost estimate was approximately $215 million on a non-discounted basis and was included in Accounts payable and accrued liabilities and Other long-term liabilities on the Consolidated Balance Sheets. The current estimated time frame for work related to these remediation activities for which TVA has a cost estimate is through 2046. Potential Liability Associated with Workers' Exposure to CCR Materials. In response to the 2008 ash spill at Kingston, TVA hired Jacobs Engineering Group, Inc. ("Jacobs") to oversee aspects of the cleanup. After the cleanup was completed, Jacobs was sued in the U.S. District Court for the Eastern District of Tennessee ("Eastern District") by employees of a contractor involved in the cleanup and family members of some of the employees. The plaintiffs alleged that Jacobs failed to take or provide proper health precautions and misled workers about the health risks associated with exposure to coal fly ash, which is a CCR material. The plaintiffs also alleged that exposure to the fly ash caused significant illnesses, including in some cases death. Other contractor employees and family members also filed lawsuits against Jacobs in the Eastern District. In the third quarter of 2023, Jacobs announced that it reached a global settlement that resolved all of these lawsuits. While TVA was not a party to any of these lawsuits, Jacobs claimed that TVA had an indemnity obligation to reimburse Jacobs under TVA's contract with Jacobs. In August 2024, TVA entered into a settlement arrangement with Jacobs and its insurers that releases TVA from all past, present, and future claims under the contract. The settlement arrangement did not have a material adverse impact on TVA's results of operations or financial condition. Legal Proceedings From time to time, TVA is party to or otherwise involved in lawsuits, claims, proceedings, investigations, and other legal matters ("Legal Proceedings") that have arisen in the ordinary course of conducting TVA's activities. General. At September 30, 2024, TVA had accrued $10 million of probable losses with respect to Legal Proceedings. Of the accrued amount, $9 million is included in Other long-term liabilities and $1 million is included in Accounts payable and accrued liabilities. No assurance can be given that TVA will not be subject to significant additional claims and liabilities. If actual liabilities significantly exceed the estimates made, TVA's results of operations, liquidity, and financial condition could be materially adversely affected. Environmental Agreements . On April 14, 2011, TVA entered into two substantively similar agreements, one with the EPA and the other with Alabama, Kentucky, North Carolina, Tennessee, and three environmental advocacy groups (collectively, the "Environmental Agreements"). To resolve alleged New Source Review claims, TVA committed under the Environmental Agreements to, among other things, take now-completed actions regarding coal units and invest $290 million in certain TVA environmental projects. Of this amount, TVA had spent approximately $284 million as of September 30, 2024. Additionally, TVA holds restricted cash in an interest earning trust to fund the remaining project commitments. Any interest earned through the trust must also be spent on agreed upon environmental projects. The total remaining committed costs, including interest earned through the trust, were approximately $7 million as of September 30, 2024. The liabilities related to the Environmental Agreements are included in Accounts payable and accrued liabilities and Other long-term liabilities on the September 30, 2024, Consolidated Balance Sheets. In conjunction with the approval of the Environmental Agreements, the TVA Board determined that it was appropriate to record TVA's obligations under the Environmental Agreements as regulatory assets, and they are included as such on the September 30, 2024, Consolidated Balance Sheets and will be recovered in rates in future periods. Case Involving Johnsonville Aeroderivative Combustion Turbine Project. On December 22, 2022, the Southern Environmental Law Center filed a lawsuit in the U.S. District Court for the Middle District of Tennessee on behalf of the Sierra Club, alleging that TVA violated the National Environmental Policy Act ("NEPA") in deciding to build a new aeroderivative combustion turbine project at its Johnsonville facility. The Sierra Club claims that TVA violated NEPA by failing to adequately analyze the climate consequences of the project, adequately address GHG mitigation in light of EOs to decarbonize the power sector, consider a reasonable range of alternatives to the project, and prepare an environmental impact statement ("EIS"). The Sierra Club requests the federal court to enter a declaratory judgment that TVA's environmental assessment ("EA") violates NEPA and that TVA's decision to issue a finding of no significant impact ("FONSI") was arbitrary, vacate the EA and FONSI, order TVA to prepare an EIS, and prohibit further construction and operation of the combustion turbines until TVA has complied with NEPA. Both parties moved for summary judgment, and on September 30, 2024, the court granted TVA's motion for summary judgment and dismissed the lawsuit. The Sierra Club has 60 days from the date of the decision to appeal. Case Involving Cumberland Combined Cycle Plant. On June 14, 2023, Appalachian Voices, the Center for Biological Diversity, and the Sierra Club filed a lawsuit in the United States District Court for the Middle District of Tennessee alleging that TVA violated NEPA in deciding to build a 1,450 MW combined cycle plant at its Cumberland facility. The plaintiffs request the court, among other things, to enter a declaratory judgment that the Cumberland EIS violated NEPA and TVA's decision to issue the Cumberland Record of Decision was arbitrary, capricious, and/or not in accordance with law; enter a declaratory judgment that TVA’s failure to supplement the Cumberland EIS violated NEPA and was arbitrary, capricious, and/or not in accordance with law; vacate the Cumberland EIS and the Cumberland Record of Decision; order TVA to prepare a revised draft EIS or supplemental EIS subject to public comment that corrects the NEPA violations identified by the plaintiffs; and enjoin further construction and operation of the Cumberland combined cycle plant until TVA has complied with NEPA. TVA filed an amended answer on September 14, 2023. On February 13, 2024, the plaintiffs filed a motion to complete the administrative record that TVA submitted in support of the EIS for this project, alleging that the administrative record submitted by TVA is incomplete. The magistrate judge issued an order granting in part and denying in part the plaintiffs' motion to complete the administrative record. TVA subsequently filed a motion challenging the magistrate judge's ruling, and TVA's motion is pending before the court. In light of the outstanding issues related to the administrative record, the court suspended the parties' summary judgment deadlines. TVA cannot predict the outcome of this litigation. Case Involving Kingston Gas-Fired Plant. On October 10, 2024, Appalachian Voices, the Center for Biological Diversity, and the Sierra Club filed a lawsuit in the United States District Court for the Eastern District of Tennessee alleging that TVA violated NEPA and TVA’s least-cost planning obligations in deciding to build a gas plant at its Kingston facility. The plaintiffs requested that the court, among other things, enter a declaratory judgment that the Kingston EIS violated NEPA and that TVA's decision to issue the Kingston Record of Decision was arbitrary, capricious, and/or not in accordance with law; enter a declaratory judgment that TVA’s least-cost-planning analysis was arbitrary, capricious, and/or not in accordance with law; vacate the Kingston Final EIS and the Kingston Record of Decision; order TVA to prepare a revised draft EIS or supplemental EIS that complies with NEPA and least-cost-planning requirements; and enjoin further construction and operation of the Kingston Gas Plant until TVA has complied with NEPA, least-cost-planning requirements, and the Administrative Procedure Act. TVA anticipates filing its response in December 2024. TVA cannot predict the outcome of this litigation.

Related Parties

Related Parties	12 Months Ended
	Sep. 30, 2024
Related Party Transactions [Abstract]
Related Parties	TVA is a wholly-owned corporate agency of the federal government, and because of this relationship, TVA's revenues and expenses are included as part of the federal budget as a revolving fund. TVA's purpose and responsibilities as an agency are described under the "Other Agencies" section of the federal budget. TVA's power program and stewardship (nonpower) programs were originally funded primarily by appropriations from Congress. In 1959, Congress passed an amendment to the TVA Act that required TVA's power program to be self-financing from power revenues and proceeds from power program financings. While TVA's power program did not directly receive appropriated funds after it became self-financing, TVA continued to receive appropriations for certain multipurpose and other nonpower mission-related activities as well as for its stewardship activities. TVA has not received any appropriations from Congress for any activities since 1999, and since that time, TVA has funded stewardship program activities primarily with power revenues. The 1959 amendment to the TVA Act also required TVA, beginning in 1961, to make annual payments to the U.S. Treasury from net power proceeds as a repayment of and as a return on the Power Program Appropriation Investment until a total of $1.0 billion of the Power Program Appropriation Investment has been repaid in accordance with the 1959 amendment. TVA fulfilled its requirement to repay $1.0 billion of the Power Program Appropriation Investment in 2014. The TVA Act requires TVA to continue making payments to the U.S. Treasury as a return on the remaining $258 million of the Power Program Appropriation Investment. TVA paid the U.S. Treasury $7 million, $6 million, and $4 million in 2024, 2023, and 2022, respectively, as a return on the Power Program Appropriation Investment. The amount of the return on the Power Program Appropriation Investment is based on the Power Program Appropriation Investment balance at the beginning of that year and the computed average interest rate payable by the U.S. Treasury on its total marketable public obligations at the same date. The interest rates payable by TVA on the Power Program Appropriation Investment were 3.02 percent, 1.99 percent, and 1.47 percent for 2024, 2023, and 2022, respectively. TVA also has access to a financing arrangement with the U.S. Treasury pursuant to the TVA Act. TVA and the U.S. Treasury entered into a memorandum of understanding under which the U.S. Treasury provides TVA with a $150 million credit facility. This credit facility has a maturity date of September 30, 2025, and is typically renewed annually. Access to this credit facility or other similar financing arrangements has been available to TVA since the 1960s. See Note 14 — Debt and Other Obligations — Credit Facility Agreements. In the normal course of business, TVA contracts with other federal agencies for sales of electricity and other services. Transactions with agencies of the federal government were as follows: Related Party Transactions At or for the years ended September 30 (in millions) 2024 2023 2022 Revenue from sales of electricity $ 118 $ 120 $ 134 Other income 273 282 296 Expenditures Operating expenses 241 234 228 Additions to property, plant, and equipment 12 8 11 Cash and cash equivalents 31 31 30 Accounts receivable, net 81 87 78 Investment funds 495 391 358 Long-term accounts receivable 35 38 43 Accounts payable and accrued liabilities 45 42 42 Long-term power bonds, net 3 1 1 Return on power program appropriation investment 7 6 4

Revenue

Revenue	12 Months Ended
	Sep. 30, 2024
Revenue from Contract with Customer [Abstract]
Revenue from Contract with Customer	17. Revenue Revenue from Sales of Electricity TVA's revenue from contracts with customers is primarily derived from the generation and sale of electricity to its customers and is included in Revenue from sales of electricity on the Consolidated Statements of Operations. Electricity is sold primarily to LPCs for distribution to their end-use customers. In addition, TVA sells electricity to directly served industrial companies, federal agencies, and others. LPC sales Approximately 92 percent of TVA's Revenue from sales of electricity for both the years ended September 30, 2024 and 2023, was from LPCs, which then distribute the power to their customers using their own distribution systems. Power is delivered to each LPC at delivery points within the LPC's service territory. TVA recognizes revenue when the customer takes possession of the power at the delivery point. For power sales, the performance obligation to deliver power is satisfied in a series over time because the sales of electricity over the term of the customer contract are a series of distinct goods that are substantially the same and have the same pattern of transfer to the customer. TVA has no continuing performance obligations subsequent to delivery. Using the output method for revenue recognition provides a faithful depiction of the transfer of electricity as customers obtain control of the power and benefit from its use at delivery. Additionally, TVA has an enforceable right to consideration for energy delivered at any discrete point in time and will recognize revenue at an amount that reflects the consideration to which TVA is entitled for the energy delivered. Directly served customers Directly served customers, including industrial customers, federal agencies, and other customers, take power for their own consumption. Similar to LPCs, power is delivered to a delivery point, at which time the customer takes possession and TVA recognizes revenue. For all power sales, the performance obligation to deliver power is satisfied in a series over time since the sales of electricity over the term of the customer contract are a series of distinct goods that are substantially the same and have the same pattern of transfer to the customer. TVA has no continuing performance obligations subsequent to delivery. Using the output method for revenue recognition provides a faithful depiction of the transfer of electricity as customers obtain control of the power and benefit from its use at delivery. Additionally, TVA has an enforceable right to consideration for energy delivered at any discrete point in time and will recognize revenue at an amount that reflects the consideration to which TVA is entitled for the energy delivered. The amount of revenue is based on contractual prices approved by the TVA Board. Customers are invoiced monthly for power delivered as measured by meters located at the delivery points. The net transaction price is offset by certain credits available to customers that are known at the time of billing. Examples of credits include items such as economic development credits to promote growth in the Tennessee Valley and demand response credits allowing TVA to reduce industrial customer usage in periods of peak demand to balance system demand. Payments are typically due within approximately one month of invoice issuance. Other Revenue Other revenue consists primarily of wheeling and network transmission charges, sales of excess steam that is a by-product of power production, delivery point charges for interconnection points between TVA and the customer, REC sales, and certain other ancillary goods or services. Disaggregated Revenues During 2024, revenues generated from TVA's electricity sales were $12.1 billion and accounted for virtually all of TVA's revenues. TVA's operating revenues by state for each of the last three years are detailed in the table below: Operating Revenues By State For the years ended September 30 (in millions) 2024 2023 2022 Alabama $ 1,768 $ 1,731 $ 1,778 Georgia 295 284 299 Kentucky 776 773 821 Mississippi 1,150 1,146 1,182 North Carolina 89 89 87 Tennessee 7,998 7,819 8,137 Virginia 47 46 48 Subtotal 12,123 11,888 12,352 Off-system sales 8 14 19 Revenue capitalized during pre-commercial plant operations (1) (3) (3) — Revenue from sales of electricity 12,128 11,899 12,371 Other revenue 186 155 169 Total operating revenues $ 12,314 $ 12,054 $ 12,540 Note (1) Represents revenue capitalized during pre-commercial operations at Paradise CTs 5-7 in 2024 and Colbert CTs 9-11 in 2023. TVA's operating revenues by customer type for each of the last three years are detailed in the table below: Operating Revenues by Customer Type For the years ended September 30 (in millions) 2024 2023 2022 Revenue from sales of electricity Local power companies $ 11,138 $ 10,903 $ 11,291 Industries directly served 868 864 926 Federal agencies and other 125 135 154 Revenue capitalized during pre-commercial plant operations (1) (3) (3) — Revenue from sales of electricity 12,128 11,899 12,371 Other revenue 186 155 169 Total operating revenues $ 12,314 $ 12,054 $ 12,540 Note (1) Represents revenue capitalized during pre-commercial operations at Paradise CTs 5-7 in 2024 and Colbert CTs 9-11 in 2023. TVA and LPCs continue to work together to meet the changing needs of consumers around the Tennessee Valley. In 2019, the TVA Board approved a Partnership Agreement option that better aligns the length of LPC power contracts with TVA's long-term commitments. Under the partnership arrangement, the LPC power contracts automatically renew each year and have a 20-year termination notice. The partnership arrangements can be terminated under certain circumstances, including TVA's failure to limit rate increases to no more than 10 percent during any consecutive five-fiscal-year period, as more specifically described in the agreements. Participating LPCs receive benefits including a 3.1 percent wholesale bill credit in exchange for their long-term commitment, which enables TVA to recover its long-term financial commitments over a commensurate period. The total wholesale bill credits to LPCs participating in the Partnership Agreement were $215 million, $199 million, and $199 million, respectively, for the years ended September 30, 2024, 2023, and 2022. In 2020, TVA provided participating LPCs a flexibility option, named Generation Flexibility, that allows them to locally generate or purchase up to approximately five percent of their average total hourly energy sales over a certain time period in order to meet their individual customers' needs. Revised flexibility agreements were made available to LPCs in August 2023 which permit projects to be located anywhere in TVA's service area, either connected to the LPC distribution system or TVA's transmission system, and make it easier for LPCs to partner in projects. As of September 30, 2024, 148 LPCs had signed the Partnership Agreement with TVA, and 102 LPCs had signed a Power Supply Flexibility Agreement. In previous years, the TVA Board approved pandemic credits, which were effective in both 2022 and 2023. These credits provided an annual 2.5 percent monthly base rate credit and applied to service provided to TVA's LPCs, their large commercial and industrial customers, and TVA directly served customers. For the years ended September 30, 2023 and 2022, pandemic credits totaled $225 million, and $228 million, respectively. The pandemic credits ended September 30, 2023. The number of LPCs by contract arrangement, the revenues derived from such arrangements for 2024, and the percentage those revenues comprised of TVA's total operating revenues for 2024, are summarized in the table below: TVA Local Power Company Contracts At or for the year ended September 30, 2024 Contract Arrangements (1) Number of LPCs Revenue from Sales of Electricity to LPCs Percentage of Total Operating Revenues 20-year termination notice 148 $ 9,621 78.1 % 5-year termination notice 5 1,517 12.3 % Total 153 $ 11,138 90.4 % Note (1) Ordinarily, the LPCs and TVA have the same termination notice period; however, in a contract with one of the LPCs with a five-year termination notice, TVA has a 10-year termination notice (which becomes a five-year termination notice if TVA loses its discretionary wholesale rate-setting authority). Certain LPCs have five-year termination notices or a shorter period if any act of Congress, court decision, or regulatory change requires or permits that election. TVA's two largest LPCs — Memphis Light, Gas and Water Division ("MLGW") and Nashville Electric Service ("NES") — have contracts with a five-year and a 20-year termination notice period, respectively. Sales to MLGW and NES accounted for nine percent and eight percent, respectively, of TVA's total operating revenues in 2024, 2023, and 2022. Contract Balances Contract assets represent an entity's right to consideration in exchange for goods and services that the entity has transferred to customers. TVA did not have any material contract assets at September 30, 2024. Contract liabilities represent an entity's obligations to transfer goods or services to customers for which the entity has received consideration (or an amount of consideration is due) from the customers. These contract liabilities are primarily related to upfront consideration received prior to the satisfaction of the performance obligation. See Economic Development Incentives below and Note 12 — Other Long-Term Liabilities — Long-Term Deferred Revenue . Economic Development Incentives.

Subsequent Events (Notes)

Subsequent Events (Notes)	12 Months Ended
	Sep. 30, 2024
Subsequent Events [Abstract]
Subsequent Events [Text Block]	. Subsequent Events In October 2024, TVA entered into an $800 million construction management agreement and lease financing arrangement with Johnsonville Aeroderivative Combustion Turbine Generation LLC ("JACTG") for the completion and lease by TVA of the Johnsonville Aeroderivative Combustion Turbine Facility ("Johnsonville Facility"). JACTG is a special single-purpose limited liability company formed in September 2024 to finance the Johnsonville Facility through a $720 million secured note issuance (the "JACTG notes") and the issuance of $80 million of membership interests subject to mandatory redemption. The membership interests were purchased by Johnsonville Holdco LLC ("JHLLC"). JHLLC is a special single-purpose entity, also formed in September 2024, established to acquire and hold the membership interests in JACTG. A non-controlling interest in JHLLC is held by a third-party through nominal membership interests, to which none of the income, expenses, and cash flows are allocated. The membership interests held by JHLLC in JACTG were purchased with proceeds from the issuance of $80 million of secured notes (the "JHLLC notes") and are subject to mandatory redemption pursuant to a schedule of amortizing, semi-annual payments due each April 1st and October 1st, with a final payment due in October 2054. The payment dates for the mandatorily redeemable membership interests are the same as those of the JHLLC notes. The sale of the JACTG notes, the membership interests in JACTG, and the JHLLC notes closed in October 2024. The JACTG notes are secured by TVA's lease payments, and the JHLLC notes are secured by JHLLC's investment in, and amounts receivable from, JACTG. TVA's lease payments to JACTG are equal to and payable on the same dates as JACTG's and JHLLC's semi-annual debt service payments. In addition to the lease payments, TVA pays administrative and miscellaneous expenses incurred by JACTG and JHLLC. Certain agreements related to this transaction contain default and acceleration provisions. Due to its participation in the design, business activity, and credit and financial support of JACTG and JHLLC, TVA has determined that it has a variable interest in each of these entities. Based on its analysis, TVA has concluded that it is the primary beneficiary of JACTG and JHLLC and, as such, is required to account for the VIEs on a consolidated basis. JHLLC's membership interests in JACTG are eliminated in consolidation. As a result of the transaction, TVA recorded $791 million in long-term debt of variable interest entities and $9 million in current maturities of long-term debt of variable interest entities.

Plant Closures (Text Block)

Plant Closures (Text Block)	12 Months Ended
	Sep. 30, 2024
Property, Plant and Equipment [Abstract]
Plant Closures	7. Plant Closures Background TVA must continuously evaluate all generating assets to ensure an optimal energy portfolio that provides safe, clean, and reliable power while maintaining flexibility and fiscal responsibility to the people of the Tennessee Valley. Based on results of assessments presented to the TVA Board in 2019, the retirement of Bull Run Fossil Plant ("Bull Run") by December 2023 was approved, and as of September 30, 2023, the facility was retired. In January 2023, TVA issued its Record of Decision to retire two coal-fired units at Cumberland Fossil Plant ("Cumberland") by the end of CY 2026 and CY 2028. In April 2024, TVA issued its Record of Decision to retire the nine coal-fired units at Kingston Fossil Plant ("Kingston") by CY 2027. In addition, TVA is evaluating the impact of retiring the balance of the coal-fired fleet by 2035, and that evaluation includes environmental reviews, public input, and TVA Board approval. Financial Impact TVA's policy is to adjust depreciation rates to reflect the most current assumptions, ensuring units will be fully depreciated by the applicable retirement dates. As a result of TVA's decision to accelerate the retirement of Bull Run, TVA has recognized a cumulative $659 million of accelerated depreciation since the second quarter of 2019 through September 30, 2023. Of this amount, $177 million and $140 million were recognized for the years ended September 30, 2023, and 2022, respectively. TVA's decision to retire the two units at Cumberland is estimated to result in approximately $16 million of additional depreciation quarterly, which does not include any potential impact from additions or retirements to net completed plant. The cumulative impact approximates $112 million of additional depreciation since January 2023, related to this decision. In addition, TVA's decision to retire the nine units at Kingston is estimated to result in approximately $9 million of additional depreciation quarterly, which does not include any potential impact from additions or retirements to net completed plant. The cumulative impact approximates $18 million of additional depreciation since April 2024, related to this decision. TVA also recognized $15 million, $14 million, and $22 million in Operating and maintenance expense related to additional inventory reserves and project write-offs for the coal-fired fleet, including Kingston, Cumberland, and Bull Run, for the years ended September 30, 2024, 2023, and 2022, respectively.

Leases (Text Block)

Leases (Text Block)	12 Months Ended
	Sep. 30, 2024
Leases [Abstract]
Lessee, Operating Leases	8 . Leases The following table provides information regarding the presentation of leases on the Consolidated Balance Sheets: Amounts Recognized on TVA's Consolidated Balance Sheets At September 30 (in millions) 2024 2023 Assets Operating Operating lease assets, net of amortization $ 149 $ 177 Finance Finance leases 729 572 Total lease assets $ 878 $ 749 Liabilities Current Operating Accounts payable and accrued liabilities $ 63 $ 71 Finance Accounts payable and accrued liabilities 80 56 Non-current Operating Other long-term liabilities 88 93 Finance Finance lease liabilities 700 576 Total lease liabilities $ 931 $ 796 TVA's leases consist primarily of railcars, equipment, real estate/land, power generating facilities, and gas pipelines. TVA's leases have various terms and expiration dates remaining from less than one year to 22 years. The components of lease costs were as follows: Lease Costs For the years ended September 30 (in millions) 2024 2023 2022 Operating lease costs (1) $ 77 $ 69 $ 56 Variable lease costs (1)(5) 258 134 78 Short-term lease costs (1) 10 18 26 Finance lease costs Amortization of lease assets (2) 79 57 58 Interest on lease liabilities (3)(4) 37 43 42 Total finance lease costs 116 100 100 Total lease costs $ 461 $ 321 $ 260 Notes (1) Costs are included in Operating and maintenance expense, Fuel expense, Purchased power expense, and Tax equivalents expense on the Consolidated Statements of Operations. (2) Expense is included in Depreciation and amortization expense on the Consolidated Statements of Operations. (3) Expense is included in Interest expense on the Consolidated Statements of Operations. (4) Certain finance leases receive regulatory accounting treatment and are reclassified to Fuel expense and Purchased power expense. (5) Variable lease costs include costs related to variable payments that are based on energy production levels, which are allocated to expense based on the determination of lease and non-lease components associated with the underlying agreements. TVA's variable lease costs are primarily related to renewable energy purchase agreements that require TVA to purchase all output from the underlying facility. Payments under those agreements are solely based on the actual output over the lease term. Certain TVA lease agreements contain renewal options. Those renewal options that are reasonably certain to be exercised are included in the lease measurements. The following table contains additional information with respect to cash and non-cash activities related to leases: Amounts Recognized on TVA's Consolidated Statements of Cash Flows For the years ended September 30 (in millions) 2024 2023 2022 Operating cash flows for operating leases $ 78 $ 77 $ 57 Operating cash flows for finance leases 37 43 42 Financing cash flows for finance leases 76 56 60 Lease assets obtained in exchange for lease obligations (non-cash) Operating leases $ 115 $ 84 $ 43 Finance leases 230 3 — TVA has certain finance leases under PPAs under which the present value of the minimum lease payments exceeds the fair value of the related lease asset at the date of measurement. This resulted in an interest rate that was higher than TVA's incremental borrowing rate. The weighted average remaining lease terms in years and the weighted average discount rate for TVA's operating and finance leases were as follows: Weighted Averages At September 30 2024 2023 Weighted average remaining lease terms Operating leases 4 years 3 years Finance leases (1) 9 years 10 years Weighted average discount rate (2) Operating leases 4.3% 4.1% Finance leases 17.6% 21.6% Note (1) One of TVA's finance leases includes an option period to extend, which TVA is reasonably certain to exercise. (2) The discount rate is calculated using the rate implicit in a lease if it is readily determinable. If the rate used by the lessor is not readily determinable, TVA uses its incremental borrowing rate as permitted by accounting guidance. The incremental borrowing rate is influenced by TVA's credit rating and lease term and as such may differ for individual leases, embedded leases, or portfolios of leased assets. . The following table presents maturities of lease liabilities and a reconciliation of the undiscounted cash flows to lease liabilities at September 30, 2024 : Future Minimum Lease Payments Minimum payments outstanding at September 30, 2024 (in millions) Operating leases 2025 $ 68 2026 34 2027 31 2028 18 2029 4 Thereafter 8 Minimum annual payments 163 Less: present value discount (12) Operating present value of net minimum lease payments $ 151 Finance leases 2025 $ 140 2026 139 2027 137 2028 133 2029 132 Thereafter 452 Minimum annual payments 1,133 Less: amount representing interest (353) Finance present value of net minimum lease payments $ 780 TVA has entered into four PPAs with renewable resource providers for solar generation and rights to charge and discharge battery energy storage systems. The systems are considered a lease component in these agreements. These PPAs have terms of 15 - 20 years and are expected to commence between January 2025 and December 2028. Total capacity payments related to these batteries over the term of these PPAs are expected to total $991 million.
Lessee, Finance Leases	8 . Leases The following table provides information regarding the presentation of leases on the Consolidated Balance Sheets: Amounts Recognized on TVA's Consolidated Balance Sheets At September 30 (in millions) 2024 2023 Assets Operating Operating lease assets, net of amortization $ 149 $ 177 Finance Finance leases 729 572 Total lease assets $ 878 $ 749 Liabilities Current Operating Accounts payable and accrued liabilities $ 63 $ 71 Finance Accounts payable and accrued liabilities 80 56 Non-current Operating Other long-term liabilities 88 93 Finance Finance lease liabilities 700 576 Total lease liabilities $ 931 $ 796 TVA's leases consist primarily of railcars, equipment, real estate/land, power generating facilities, and gas pipelines. TVA's leases have various terms and expiration dates remaining from less than one year to 22 years. The components of lease costs were as follows: Lease Costs For the years ended September 30 (in millions) 2024 2023 2022 Operating lease costs (1) $ 77 $ 69 $ 56 Variable lease costs (1)(5) 258 134 78 Short-term lease costs (1) 10 18 26 Finance lease costs Amortization of lease assets (2) 79 57 58 Interest on lease liabilities (3)(4) 37 43 42 Total finance lease costs 116 100 100 Total lease costs $ 461 $ 321 $ 260 Notes (1) Costs are included in Operating and maintenance expense, Fuel expense, Purchased power expense, and Tax equivalents expense on the Consolidated Statements of Operations. (2) Expense is included in Depreciation and amortization expense on the Consolidated Statements of Operations. (3) Expense is included in Interest expense on the Consolidated Statements of Operations. (4) Certain finance leases receive regulatory accounting treatment and are reclassified to Fuel expense and Purchased power expense. (5) Variable lease costs include costs related to variable payments that are based on energy production levels, which are allocated to expense based on the determination of lease and non-lease components associated with the underlying agreements. TVA's variable lease costs are primarily related to renewable energy purchase agreements that require TVA to purchase all output from the underlying facility. Payments under those agreements are solely based on the actual output over the lease term. Certain TVA lease agreements contain renewal options. Those renewal options that are reasonably certain to be exercised are included in the lease measurements. The following table contains additional information with respect to cash and non-cash activities related to leases: Amounts Recognized on TVA's Consolidated Statements of Cash Flows For the years ended September 30 (in millions) 2024 2023 2022 Operating cash flows for operating leases $ 78 $ 77 $ 57 Operating cash flows for finance leases 37 43 42 Financing cash flows for finance leases 76 56 60 Lease assets obtained in exchange for lease obligations (non-cash) Operating leases $ 115 $ 84 $ 43 Finance leases 230 3 — TVA has certain finance leases under PPAs under which the present value of the minimum lease payments exceeds the fair value of the related lease asset at the date of measurement. This resulted in an interest rate that was higher than TVA's incremental borrowing rate. The weighted average remaining lease terms in years and the weighted average discount rate for TVA's operating and finance leases were as follows: Weighted Averages At September 30 2024 2023 Weighted average remaining lease terms Operating leases 4 years 3 years Finance leases (1) 9 years 10 years Weighted average discount rate (2) Operating leases 4.3% 4.1% Finance leases 17.6% 21.6% Note (1) One of TVA's finance leases includes an option period to extend, which TVA is reasonably certain to exercise. (2) The discount rate is calculated using the rate implicit in a lease if it is readily determinable. If the rate used by the lessor is not readily determinable, TVA uses its incremental borrowing rate as permitted by accounting guidance. The incremental borrowing rate is influenced by TVA's credit rating and lease term and as such may differ for individual leases, embedded leases, or portfolios of leased assets. . The following table presents maturities of lease liabilities and a reconciliation of the undiscounted cash flows to lease liabilities at September 30, 2024 : Future Minimum Lease Payments Minimum payments outstanding at September 30, 2024 (in millions) Operating leases 2025 $ 68 2026 34 2027 31 2028 18 2029 4 Thereafter 8 Minimum annual payments 163 Less: present value discount (12) Operating present value of net minimum lease payments $ 151 Finance leases 2025 $ 140 2026 139 2027 137 2028 133 2029 132 Thereafter 452 Minimum annual payments 1,133 Less: amount representing interest (353) Finance present value of net minimum lease payments $ 780 TVA has entered into four PPAs with renewable resource providers for solar generation and rights to charge and discharge battery energy storage systems. The systems are considered a lease component in these agreements. These PPAs have terms of 15 - 20 years and are expected to commence between January 2025 and December 2028. Total capacity payments related to these batteries over the term of these PPAs are expected to total $991 million.

Research and Development

Research and Development	12 Months Ended
	Sep. 30, 2024
Research and Development [Abstract]
Collaborative Arrangement Disclosure	21 . Collaborative Arrangement In 2023, TVA, Ontario Power Generation, BWRX TCA sp. z.o.o., and GE Hitachi Nuclear Energy ("GEH") entered into a multi-party collaborative arrangement to advance the global deployment of the GEH BWRX-300 small modular reactor. GEH is responsible for standard design development. Under the agreement, TVA will contribute up to $88 million for design costs incurred by GEH through 2026. At the time feasibility is determined, TVA will have the right to use the design and may receive additional economic benefits. Payments pursuant to the agreement are recorded as research and development expense, which is reflected as Operating and maintenance expense on TVA's Consolidated Statements of Operations in the period incurred. TVA recorded $41 million and $31 million of expenses related to this agreement for the years ended September 30, 2024 and 2023, respectively. TVA also had a $6 million letter of credit posted under this arrangement at September 30, 2024.

Pay vs Performance Disclosure

Pay vs Performance Disclosure - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Pay vs Performance Disclosure
Net income (loss)	$ 1,135	$ 500	$ 1,108

Insider Trading Arrangements

Insider Trading Arrangements	3 Months Ended
	Sep. 30, 2024
Trading Arrangements, by Individual
Rule 10b5-1 Arrangement Adopted	false
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false

Summary of Significant Accoun_2

Summary of Significant Accounting Policies [Policy Text Block]	12 Months Ended
	Sep. 30, 2024
Accounting Policies [Abstract]
General	General The Tennessee Valley Authority ("TVA") is a corporate agency and instrumentality of the United States ("U.S.") that was created in 1933 by federal legislation in response to a proposal by President Franklin D. Roosevelt. TVA was created to, among other things, improve navigation on the Tennessee River, reduce the damage from destructive flood waters within the Tennessee River system and downstream on the lower Ohio and Mississippi Rivers, further the economic development of TVA's service area in the southeastern U.S., and sell the electricity generated at the facilities TVA operates. Today, TVA operates the nation's largest public power system and supplies power in most of Tennessee, northern Alabama, northeastern Mississippi, and southwestern Kentucky and in portions of northern Georgia, western North Carolina, and southwestern Virginia to a population of approximately 10 million people. TVA also manages the Tennessee River, its tributaries, and certain shorelines to provide, among other things, year-round navigation, flood damage reduction, and affordable and reliable electricity. Consistent with these primary purposes, TVA also manages the river system and public lands to provide recreational opportunities, adequate water supply, improved water quality, cultural and natural resource protection, and economic development. TVA performs these management duties in cooperation with other federal and state agencies that have jurisdiction and authority over certain aspects of the river system. In addition, the TVA Board of Directors ("TVA Board") has established two councils — the Regional Resource Stewardship Council and the Regional Energy Resource Council — to advise TVA on its stewardship activities in the Tennessee Valley and its energy resource activities. The power program has historically been separate and distinct from the stewardship programs. It is required to be self-supporting from power revenues and proceeds from power financings, such as proceeds from the issuance of bonds, notes, or other evidences of indebtedness (collectively, "Bonds"). Although TVA does not currently receive Congressional appropriations, it is required to make annual payments to the United States Department of the Treasury ("U.S. Treasury") as a return on the government's appropriation investment in TVA's power facilities (the "Power Program Appropriation Investment"). In the 1998 Energy and Water Development Appropriations Act, Congress directed TVA to fund essential stewardship activities related to its management of the Tennessee River system and nonpower or stewardship properties with power revenues in the event that there were insufficient appropriations or other available funds to pay for such activities in any fiscal year. Congress has not provided any appropriations to TVA to fund such activities since 1999. Consequently, during 2000, TVA began paying for essential stewardship activities primarily with power revenues, with the remainder funded with user fees and other forms of revenues derived in connection with those activities. The activities related to stewardship properties do not meet the criteria of an operating segment under accounting principles generally accepted in the United States of America ("GAAP"). Accordingly, these assets and properties are included as part of the power program, TVA's only operating segment. Power rates are established by the TVA Board as authorized by the Tennessee Valley Authority Act of 1933, as amended ("TVA Act"). The TVA Act requires TVA to charge rates for power that will produce gross revenues sufficient to provide funds for operation, maintenance, and administration of its power system; payments to states and counties in lieu of taxes ("tax equivalents"); debt service on outstanding indebtedness; payments to the U.S. Treasury in repayment of and as a return on the Power Program Appropriation Investment; and such additional margin as the TVA Board may consider desirable for investment in power system assets, retirement of outstanding Bonds in advance of maturity, additional reduction of the Power Program Appropriation Investment, and other purposes connected with TVA's power business. TVA fulfilled its requirement to repay $1.0 billion of the Power Program Appropriation Investment with the 2014 payment; therefore, this repayment obligation is no longer a component of rate setting. In setting TVA's rates, the TVA Board is charged by the TVA Act to have due regard for the primary objectives of the TVA Act, including the objective that power shall be sold at rates as low as are feasible. Rates set by the TVA Board are not subject to review or approval by any state or other federal regulatory body.
Fiscal Year	Fiscal Year TVA's fiscal year ends September 30. Years (2024, 2023, etc.) refer to TVA's fiscal years unless they are preceded by "CY," in which case the references are to calendar years.
Cost-Based Regulation	Cost-Based Regulation Since the TVA Board is authorized by the TVA Act to set rates for power sold to its customers, TVA is self-regulated. Additionally, TVA's regulated rates are designed to recover its costs. Based on current projections, TVA believes that rates, set at levels that will recover TVA's costs, can be charged and collected. As a result of these factors, TVA records certain assets and liabilities that result from the regulated ratemaking process that would not be recorded under GAAP for non-regulated entities. Regulatory assets generally represent incurred costs that have been deferred because such costs are probable of future recovery in customer rates. Regulatory liabilities generally represent obligations to make refunds to customers for previous collections for costs that are not likely to be incurred or deferral of gains that will be credited to customers in future periods. TVA assesses whether the regulatory assets are probable of future recovery by considering factors such as applicable regulatory changes, potential legislation, and changes in technology. Based on these assessments, TVA believes the existing regulatory assets are probable of recovery. This determination reflects the current regulatory and political environment and is subject to change in the future. If future recovery of regulatory assets ceases to be probable, or TVA is no longer considered to be a regulated entity, then costs would be required to be written off. All regulatory asset write offs would be required to be recognized in earnings in the period in which future recovery ceases to be probable or in which TVA is no longer considered to be a regulated entity.
Basis of Presentation	Basis of Presentation The accompanying consolidated financial statements, which have been prepared in accordance with GAAP, include the accounts of TVA and variable interest entities ("VIEs") of which TVA is the primary beneficiary. See Note 11 — Variable Interest Entities
Use of Estimates	Use of Estimates The preparation of financial statements requires TVA to estimate the effects of various matters that are inherently uncertain as of the date of the consolidated financial statements. Although the consolidated financial statements are prepared in conformity with GAAP, TVA is required to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities, and the amounts of revenues and expenses reported during the reporting period. Each of these estimates varies in regard to the level of judgment involved and its potential impact on TVA's financial results. Estimates are considered critical either when a different estimate could have reasonably been used, or where changes in the estimate are reasonably likely to occur from period to period, and such use or change would materially impact TVA's financial condition, results of operations, or cash flows.
Cash and Cash Equivalents and Restricted Cash and Investments	Cash, Cash Equivalents, and Restricted Cash Cash includes cash on hand, non-interest bearing cash, and deposit accounts. All highly liquid investments with original maturities of three months or less are considered cash equivalents. Cash and cash equivalents that are restricted, as to withdrawal or use under the terms of certain contractual agreements, are recorded in Other long-term assets on the Consolidated Balance Sheets. Restricted cash and cash equivalents include cash held in trusts that are currently restricted for TVA economic development loans and for certain TVA environmental programs in accordance with agreements related to compliance with certain environmental regulations. See Note 22 — Commitments and Contingencies — Legal Proceedings — Environmental Agreements . The following table provides a reconciliation of cash, cash equivalents, and restricted cash reported on the Consolidated Balance Sheets and Consolidated Statements of Cash Flows: Cash, Cash Equivalents, and Restricted Cash At September 30 (in millions) 2024 2023 Cash and cash equivalents $ 502 $ 501 Restricted cash and cash equivalents included in Other long-term assets 21 20 Total cash, cash equivalents, and restricted cash $ 523 $ 521
Allowance for Uncollectible Accounts	Allowance for Uncollectible Accounts TVA recognizes an allowance that reflects the current estimate for credit losses expected to be incurred over the life of the financial assets based on historical experience, current conditions, and reasonable and supportable forecasts that affect the collectability of the reported amounts. The appropriateness of the allowance is evaluated at the end of each reporting period. To determine the allowance for trade receivables, TVA considers historical experience and other currently available information, including events such as customer bankruptcy and/or a customer failing to fulfill payment arrangements by the due date. TVA's corporate credit department also performs an assessment of the financial condition of customers and the credit quality of the receivables. In addition, TVA reviews other reasonable and supportable forecasts to determine if the allowance for uncollectible amounts should be further adjusted in accordance with the accounting guidance for Current Expected Credit Losses. To determine the allowance for loans receivables, TVA aggregates loans into the appropriate pools based on the existence of similar risk characteristics such as collateral types and internal assessed credit risks. In situations where a loan exhibits unique risk characteristics and is no longer expected to experience similar risks to the rest of its pool, the loan will be evaluated separately. TVA derives an annual loss rate based on historical loss and then adjusts the rate to reflect TVA's consideration of available information on current conditions and reasonable and supportable future forecasts. This information may include economic and business conditions, default trends, and other internal and external factors. For periods beyond the reasonable and supportable forecast period, TVA uses the current calculated long-term average historical loss rate for the remaining life of the loan portfolio. The allowance for uncollectible accounts was less than $1 million at both September 30, 2024 and 2023, for trade accounts receivable. Additionally, loans receivable of $105 million and $104 million at September 30, 2024 and 2023, respectively, are included in Accounts receivable, net and Other long-term assets for the current and long-term portions, respectively. Loans receivables are reported net of allowances for uncollectible accounts of $2 million a n
Revenues	Revenues TVA recognizes revenue from contracts with customers to depict the transfer of goods or services to customers in an amount to which the entity expects to be entitled in exchange for those goods or services. For the generation and transmission of electricity, this is generally at the time the power is delivered to a metered customer delivery point for the customer's consumption or distribution. As a result, revenues from power sales are recorded as electricity is delivered to customers. In addition to power sales invoiced and recorded during the month, TVA accrues estimated unbilled revenues for power sales provided to five customers whose billing date occurs prior to the end of the month. Exchange power sales are presented in the accompanying Consolidated Statements of Operations as a component of sales of electricity. Exchange power sales are sales of excess power after meeting TVA native load and directly served requirements. Native load refers to the customers on whose behalf a company, by statute, franchise, regulatory requirement, or contract, has undertaken an obligation to serve. TVA engages in other arrangements in addition to power sales. Certain other revenue from activities related to TVA's overall mission is recorded in Other revenue. Revenues that are not related to the overall mission are recorded in Other income, net.
Inventories	Inventories Certain Fuel, Materials, and Supplies . Materials and supplies inventories are valued using an average unit cost method. A new average cost is computed after each inventory purchase transaction, and inventory issuances are priced at the latest moving weighted average unit cost. Coal, fuel oil, and natural gas inventories are valued using an average cost method. A new weighted average cost is computed monthly, and monthly issues are priced accordingly. Renewable Energy Certificates. TVA accounts for Renewable Energy Certificates ("RECs") using the specific identification cost method. RECs that are acquired through power purchases are recorded as inventory and charged to purchased power expense when the RECs are subsequently used or sold. TVA assigns a value to the RECs at the inception of the power purchase arrangement using a relative standalone selling price approach. RECs created through TVA-owned asset generation are recorded at zero cost. Emission Allowances . TVA accounts for emission allowances using the specific identification cost method. Allowances that are acquired through third party purchases are recorded as inventory at cost and charged to operating expense based on tons emitted during the respective compliance periods. Allowance for Inventory Obsolescence . TVA reviews materials and supplies inventories by category and usage on a periodic basis. Each category is assigned a probability of becoming obsolete based on the type of material and historical usage data. TVA has a fleet-wide inventory management policy for each generation type. Based on the estimated value of the inventory, TVA adjusts its allowance for inventory obsolescence.
Property, Plant, and Equipment, and Depreciation	Property, Plant, and Equipment, and Depreciation Property, Plant, and Equipment. Additions to plant are recorded at cost, which includes direct and indirect costs. The cost of current repairs and minor replacements is charged to operating expense. When property, plant, and equipment is retired, accumulated depreciation is charged for the original cost of the assets. Gains or losses are only recognized upon the sale of land or an entire operating unit. TVA capitalizes certain costs incurred in connection with developing or obtaining internal-use software. Capitalized software costs are included in Property, plant, and equipment on the Consolidated Balance Sheets and are generally amortized over seven years. Nuclear Fuel. Nuclear fuel, which is included in Property, plant, and equipment, is valued using the average cost method for raw materials and the specific identification method for nuclear fuel in a reactor. Amortization of nuclear fuel in a reactor is calculated on a units-of-production basis and is included in fuel expense. TVA, the U.S. Department of Energy ("DOE"), and certain nuclear fuel contractors have entered into agreements, referred to as the Down-blend Offering for Tritium ("DBOT"), that provide for the production, processing, and storage of low-enriched uranium that is to be made using e fabricated into fuel for use in a nuclear power plant. Production of the low-enriched uranium began in 2019 and is contracted to continue through September 2027. Contract activity after that date will consist of storage and flag management. Flag management ensures that the uranium is unencumbered by policy restrictions, so that it can be used in connection with the production of tritium. Under the terms of the interagency agreement between the DOE and TVA, the DOE will reimburse TVA for a portion of the costs of converting the highly enriched uranium to low-enriched uranium. Since 2019, TVA has received $284 million in reimbursements from the DOE, which is recorded as a reduction in nuclear fuel inventory costs. At September 30, 2024, TVA recorded $13 million in Accounts receivable, net related to this agreement. Depreciation. TVA accounts for depreciation of its properties using the composite depreciation convention of accounting. Under the composite method, assets with similar economic characteristics are grouped and depreciated as one asset. Depreciation is generally computed on a straight-line basis over the estimated service lives of the various classes of assets. The estimation of asset useful lives requires management judgment, supported by external depreciation studies of historical asset retirement experience. Depreciation rates are determined based on external depreciation studies that are updated approximately every five years, with the latest study implemented in 2022. Depreciation expense for the years ended September 30, 2024, 2023, and 2022 was $1.8 billion, $1.9 billion, and $1.8 billion, respectively. Depreciation expense expressed as a percentage of the average annual depreciable completed plant was 2.92 percent for 2024, 3.14 percent for 2023, and 2.98 percent for 2022. Average depreciation rates by asset class are as follows: Property, Plant, and Equipment Depreciation Rates At September 30 2024 2023 2022 Asset Class Nuclear 2.71 2.73 2.72 Coal-fired (1) 4.13 4.98 4.27 Hydroelectric 1.83 1.82 1.85 Gas and oil-fired 3.31 3.17 3.38 Transmission 1.52 1.52 1.51 Other 4.98 4.43 3.64 Note (1) The rates include the acceleration of depreciation related to retiring certain coal-fired units and potentially retiring the remainder of the coal-fired fleet by 2035. See Note 7 — Plant Closures . Reacquired Rights . TVA previously entered into leasing transactions to obtain third-party financing for 24 peaking CTs as well as certain qualified technological equipment and software (“QTE”). All of the lease proceeds were accounted for as financing obligations due to TVA’s continuing involvement with the combustion turbine facilities and the QTE during the leaseback term. These financial obligations were paid off, and TVA acquired the residual leasehold interests for all of this equipment and recorded the cash consideration as reacquired rights, which is an intangible asset included in property, plant, and equipment on the Consolidated Balance Sheet. As of September 30, 2024 and 2023, property, plant, and equipment includes intangible reacquired rights, net of amortization, of $312 million and $324 million, respectively. Reacquired rights are amortized over the estimated useful lives of the underlying CTs which range from 30 to 35 years. Amortization expense was $11 million, $10 million, and $6 million for the years ended September 30, 2024, 2023, and 2022, respectively, and accumulated amortization at September 30, 2024 and 2023 totaled $63 million and $52 million, respectively. At September 30, 2024, the estimated aggregate amortization expense for each of the next five years and thereafter is shown below: 2025 2026 2027 2028 2029 Thereafter Reacquired Rights $ 12 $ 11 $ 12 $ 11 $ 11 $ 255 Impairment of Assets. TVA evaluates long-lived assets for impairment when events or changes in circumstances indicate that the carrying value of such assets may not be recoverable. For long-lived assets, TVA bases its evaluation on impairment indicators such as the nature of the assets, the future economic benefit of the assets, any historical or future profitability measurements, regulatory approval and ability to set rates at levels that allow for recoverability of the assets, and other external market conditions or factors that may be present. If such impairment indicators are present or other factors exist that indicate that the carrying amount of an asset may not be recoverable, TVA determines whether an impairment has occurred based on an estimate of undiscounted cash flows attributable to the asset as compared with the carrying value of the asset. If an impairment has occurred, the amount of the impairment recognized is measured as the excess of the asset's carrying value over its fair value. Additionally, TVA regularly evaluates construction projects. If the project is canceled or deemed to have no future economic benefit, the project is written off as an asset impairment or, upon TVA Board approval, reclassified as a regulatory asset and amortized over the Board-approved period. See Note 7 — Plant Closures
Lessee, Leases	Leases TVA recognizes a lease asset and lease liability for leases with terms of greater than 12 months. Lease assets represent TVA's right to use an underlying asset for the lease term, and lease liabilities represent TVA's obligation to make lease payments arising from the lease, both of which are recognized based on the present value of the future minimum lease payments over the lease term at the commencement date. TVA has certain lease agreements that include variable lease payments that are based on energy production levels. These variable lease payments are not included in the measurement of the lease assets or lease liabilities but are recognized in the period in which the expenses are incurred. While not specifically structured as leases, certain power purchase agreements ("PPAs") are deemed to contain a lease of the underlying generating units when the terms convey the right to control the use of the assets. Amounts recorded for these leases are generally based on the amount of the scheduled capacity payments due over the remaining terms of the PPAs, the terms of which vary. The total lease obligations included in Accounts payable and accrued liabilities, Other long-term liabilities, and Finance lease liabilities related to these agreements were $550 million and $121 million for finance and operating leases, respectively, at September 30, 2024. The total lease obligations included in Accounts payable and accrued liabilities, Other long-term liabilities, and Finance lease liabilities related to these agreements were $390 million and $135 million for finance and operating leases, respectively, at September 30, 2023. TVA has agreements with lease and non-lease components and has elected to separate lease and non-lease components. Consideration is allocated to lease and non-lease components generally based on relative standalone price basis. Variable lease costs included in the agreements are allocated based on the determination of lease and non-lease components. TVA has lease agreements which include options for renewal and early termination. The intent to renew a lease varies depending on the lease type and asset. Renewal options that are reasonably certain to be exercised are included in the lease measurements. The decision to terminate a lease early is dependent on various economic factors. No termination options have been included in TVA's lease measurements. Leases with an initial term of 12 months or less, which do not include an option to extend the initial term of the lease to greater than 12 months that TVA is reasonably certain to exercise, are not recorded on the Consolidated Balance Sheets at September 30, 2024. Operating leases are recognized on a straight-line basis over the term of the lease agreement. Rent expense associated with short-term leases and variable leases is recorded in Operating and maintenance expense, Fuel expense, or Purchased power expense on the Consolidated Statements of Operations. Expenses associated with finance leases result in the separate presentation of interest expense on the lease liability and amortization expense of the related lease asset on the Consolidated Statements of Operations.
Decommissioning Costs	Decommissioning Costs TVA recognizes legal obligations associated with the future retirement of certain tangible long-lived assets. These obligations relate to fossil fuel-fired generating plants, nuclear generating plants, hydroelectric generating plants/dams, transmission structures, and other property-related assets. Activities involved with retiring these assets could include decontamination and demolition of structures, removal and disposal of wastes, and site restoration. Revisions to the forecasted costs of decommissioning activities are made whenever factors indicate that the timing or amounts of estimated cash flows have changed materially. Studies are updated for both nuclear and non-nuclear decommissioning costs at least every five years. Any accretion or depreciation expense related to these liabilities and assets is charged to a regulatory asset. See Note 10 — Regulatory Assets and Liabilities — Nuclear Decommissioning Costs and Non-Nuclear Decommissioning Costs and Note 13 — Asset Retirement Obligations.
Investment Funds	Investment Funds Investment funds consist primarily of trust funds designated to fund decommissioning requirements (see Note 22 — Commitments and Contingencies — Contingencies — Decommissioning Costs ), the Supplemental Executive Retirement Plan ("SERP") (see Note 20 — Benefit Plans — Overview of Plans and Benefits — Supplemental Executive Retirement Plan ), the Deferred Compensation Plan ("DCP"), and the Restoration Plan ("RP"). The Nuclear Decommissioning Trust ("NDT") holds funds primarily for the ultimate decommissioning of TVA's nuclear power plants. The Asset Retirement Trust ("ART") holds funds primarily for the costs related to the future closure and retirement of TVA's other long-lived assets. The NDT, ART, SERP, DCP, and RP funds are invested in portfolios of securities generally designed to achieve a return in line with overall equity and debt market performance. The NDT, ART, SERP, DCP, and RP funds are all classified as trading.
Research and Development Costs	Research and Development Costs Research and development costs are expensed when incurred. TVA's research programs include those related to power delivery technologies, emerging technologies (clean energy, renewables, distributed resources, and energy efficiency), technologies related to generation (fossil fuel, nuclear, and hydroelectric), and environmental technologies.
Tax Equivalents	Tax Equivalents TVA is not subject to federal income taxation. In addition, neither TVA nor its property, franchises, or income is subject to taxation by states or their subdivisions. The TVA Act requires TVA to make payments to states and counties in which TVA conducts its power operations and in which TVA has acquired power properties previously subject to state and local taxation. The total amount of these payments is five percent of gross revenues from sales of power during the preceding year, excluding sales or deliveries to other federal agencies and off-system sales with other utilities, with a provision for minimum payments under certain circumstances. TVA calculates tax equivalent expense by subtracting the prior year fuel cost-related tax equivalent regulatory asset or liability from the payments made to the states and counties during the current year and adding back the current year fuel cost-related tax equivalent regulatory asset or liability. Fuel cost-related tax equivalent expense is recognized in the same accounting period in which the fuel cost-related revenue is recognized.
Maintenance Costs	Maintenance Costs
Pre-Commercial Plant Operations	Pre-Commercial Plant Operations As part of the process of completing the construction of a generating unit, the electricity produced is used to serve the demands of the electric system. TVA estimates revenues earned during pre-commercial operations at the fair value of the energy delivered based on TVA's hourly incremental dispatch cost. Pre-commercial plant operations began on Paradise CT Units 5-7 in the first quarter of 2024, and the units became operational on December 29, 2023. Estimated revenue of $3 million related to this project was capitalized to offset project costs for the year ended September 30, 2024. TVA also capitalized related fuel costs for this project of $3 million for the year ended September 30, 2024, all of which was recognized in the three months ended December 31, 2023.

Deferred Costs, Capitalized, _2

Deferred Costs, Capitalized, Prepaid, and Other Assets (Policies)	12 Months Ended
	Sep. 30, 2024
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Derivatives, Methods of Accounting, Hedging Derivatives	Commodity Contract Derivative Assets. TVA enters into certain derivative contracts for natural gas that require physical delivery of the contracted quantity of the commodity as well as certain financial derivative contracts to hedge exposure to the price of natural gas. Commodity contract derivative assets classified as current include deliveries or settlements that will occur within 12 months or less. See Note 15 — Risk Management Activities and Derivative Transactions — Derivatives Not Receiving Hedge Accounting Treatment — Commodity Derivatives and — Commodity Derivatives under the FHP for a

Deferred Costs, Capitalized, _3

Deferred Costs, Capitalized, Prepaid, and Other Assets (Policies)	12 Months Ended
	Sep. 30, 2024
Assets, Noncurrent [Abstract]
Financing Receivable	Loans and Other Long-Term Receivables
Transfers and Servicing of Financial Assets, Transfers of Financial Assets, Financings, Policy	EnergyRight ® Receivables . In association with the EnergyRight ® program, TVA's local power company customers ("LPCs") offer financing to end-use customers for the purchase of energy-efficient equipment. Depending on the nature of the energy-efficiency project, loans may have a maximum term of five years or 10 years. TVA purchases the resulting loans receivable from its LPCs. The loans receivable are then transferred to a third-party bank with which TVA has agreed to repay in full any loans receivable that have been in default for 180 days or more or that TVA has determined are uncollectible. Given this continuing involvement, TVA accounts for the transfer of the loans receivable as secured borrowings. The current and long-term portions of the loans receivable are reported in Accounts receivable, net and Other long-term assets, respectively, on TVA's Consolidated Balance Sheets. At both September 30, 2024 and 2023, the carrying amount of the loans receivable, net of discount, reported in Accounts receivable, was $12 million. See Note 12 — Other Long-Term Liabilities for information regarding the associated financing obligation.
Credit Loss, Financial Instrument	Allowance for Loan Losses. The allowance for loan losses is an estimate of expected credit losses, measured over the estimated life of the loan receivables, that considers reasonable and supportable forecasts of future economic conditions in addition to information about historical experience and current conditions. See Note 1 — Summary of Significant Accounting Policies — Allowance for Uncollectible Accounts . The allowance components, which consist of a collective allowance and specific loans allowance, are based on the risk characteristics of TVA's loans. Loans that share similar risk characteristics are evaluated on a collective basis in measuring credit losses, while loans that do not share similar risk characteristics with other loans are evaluated on an individual basis. Allowance Components At September 30 (in millions) 2024 2023 EnergyRight ® loan reserve $ 1 $ 1 Economic development loan collective reserve — 1 Economic development loan specific loan reserve 1 1 Total allowance for loan losses $ 2 $ 3
Service Agreements	Prepaid Long-Term Service Agreements. TVA has entered into various long-term service agreements for major maintenance activities at certain of its combined cycle plants. TVA uses the direct expense method of accounting for these arrangements. TVA accrues for parts when it takes ownership and for contractor services when they are rendered. Under certain of these agreements, payments made exceed the value of parts received and services rendered. The current and long-term portions of the resulting prepayments are reported in Other current assets and Other long-term assets, respectively, on TVA's Consolidated Balance Sheets. At September 30, 2024 and 2023, prepayments of $7 million and $25 million, respectively, were recorded in Other current assets.
Commodity contract derivative asset	Commodity Contract Derivative Assets. TVA enters into certain derivative contracts for natural gas that require physical delivery of the contracted quantity of the commodity as well as certain financial derivative contracts to hedge exposure to the price of natural gas. See Note 15 — Risk Management Activities and Derivative Transactions — Derivatives Not Receiving Hedge Accounting Treatment — Commodity Derivatives and — Commodity Derivatives under the FHP for a
Goodwill and Intangible Assets, Intangible Assets, Policy	Cloud Assets. TVA has capitalized the implementation costs of hosting arrangements that are considered service contracts as cloud assets. The cloud assets are amortized over the term of the associated hosting arrangements. The current and long-term portions of the cloud assets are reported in Other current assets and Other long-term assets, respectively, on TVA’s Consolidated Balance Sheets. At September 30, 2024, and September 30, 2023, the carrying amount of the cloud assets reported in Other current assets was $13 million and $7 million, respectively.

Variable Interest Entities (Pol

Variable Interest Entities (Policies)	12 Months Ended
	Sep. 30, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Summary of Impact of VIEs on Consolidated Balance Sheets	The financial statement items attributable to carrying amounts and classifications of JSCCG, Holdco, and SCCG as of September 30, 2024 and 2023, as reflected on the Consolidated Balance Sheets, are as follows: Summary of Impact of VIEs on Consolidated Balance Sheets At September 30 (in millions) 2024 2023 Current liabilities Accrued interest $ 9 $ 9 Accounts payable and accrued liabilities 1 1 Current maturities of long-term debt of variable interest entities 37 35 Total current liabilities 47 45 Other liabilities Other long-term liabilities 16 17 Long-term debt, net Long-term debt of variable interest entities, net 897 933 Total liabilities $ 960 $ 995
Consolidation, Variable Interest Entity, Policy	A VIE is an entity that either (i) has insufficient equity to permit the entity to finance its activities without additional subordinated financial support or (ii) has equity investors who lack the characteristics of owning a controlling financial interest. When TVA determines that it has a variable interest in a VIE, a qualitative evaluation is performed to assess which interest holders have the power to direct the activities that most significantly impact the economic performance of the entity and have the obligation to absorb losses or receive benefits that could be significant to the entity. The evaluation considers the purpose and design of the business, the risks that the business was designed to create and pass along to other entities, the activities of the business that can be directed and which party can direct them, and the expected relative impact of those activities on the economic performance of the business through its life. TVA has the power to direct the activities of an entity when it has the

Asset Retirement Obligations As

Asset Retirement Obligations Asset Retirement Obligations (Policies)	12 Months Ended
	Sep. 30, 2024
Asset Retirement Obligation Disclosure [Abstract]
Asset Retirement Obligations, Policy	Decommissioning Costs TVA recognizes legal obligations associated with the future retirement of certain tangible long-lived assets. These obligations relate to fossil fuel-fired generating plants, nuclear generating plants, hydroelectric generating plants/dams, transmission structures, and other property-related assets. Activities involved with retiring these assets could include decontamination and demolition of structures, removal and disposal of wastes, and site restoration. Revisions to the forecasted costs of decommissioning activities are made whenever factors indicate that the timing or amounts of estimated cash flows have changed materially. Studies are updated for both nuclear and non-nuclear decommissioning costs at least every five years. Any accretion or depreciation expense related to these liabilities and assets is charged to a regulatory asset. See Note 10 — Regulatory Assets and Liabilities — Nuclear Decommissioning Costs and Non-Nuclear Decommissioning Costs and Note 13 — Asset Retirement Obligations.

Benefit Plans Benefit Plans (Po

Benefit Plans Benefit Plans (Policies)	12 Months Ended
	Sep. 30, 2024
Retirement Benefits [Abstract]
Benefit Plans	Accounting Mechanisms Regulatory Accounting. TVA has classified all amounts related to unrecognized prior service costs/(credits), net actuarial gains or losses, and the funded status as regulatory assets or liabilities as such amounts are probable of collection in future rates. Additionally, TVA recognizes pension costs as regulatory assets or regulatory liabilities to the extent that the amount calculated under U.S. GAAP as pension expense differs from the amount TVA contributes to the pension plan as pension plan contributions. As a result of plan design changes, future contributions are expected to exceed the expense calculated under U.S. GAAP. Accordingly, TVA discontinued this regulatory accounting practice as all such deferred costs were recovered as of September 30, 2023. Cost Method. TVA uses the projected unit credit cost method to determine the service cost and the projected benefit obligation for retirement, termination, and ancillary benefits. Under this method, a "projected accrued benefit" is calculated at the beginning of the year and at the end of the year for each benefit that may be payable in the future. The "projected accrued benefit" is based on the plan's accrual formula and upon service at the beginning or end of the year, but it uses final average compensation, social security benefits, and other relevant factors projected to the age at which the employee is assumed to leave active service. The projected benefit obligation is the actuarial present value of the "projected accrued benefits" at the beginning of the year for employed participants and is the actuarial present value of all benefits for other participants. The service cost is the actuarial present value of the difference between the "projected accrued benefits" at the beginning and end of the year. Amortization of Net Gain or Loss. TVA utilizes the corridor approach for gain/loss amortization. Differences between actuarial assumptions and actual plan results are deferred and amortized into periodic cost only when the accumulated differences exceed 10 percent of the greater of the projected benefit obligation or the market-related value of plan assets. If necessary, the excess is amortized over the average future expected working lifetime of participants expected to receive benefits, which is approximately 11 years for the pension plan and 15 years for the post-retirement plans. Amortization of Prior Service Cost/(Credit). Amortization of net prior service cost/(credit) resulting from a plan change is included as a component of period expense in the year first recognized and every year thereafter until it is fully amortized. The increase or decrease in the benefit obligation due to the plan change is amortized over the average remaining service period of participating employees expected to receive benefits under the plan. The pension and post-retirement plans currently have prior service costs/(credits) from plan changes made in 2016, 2018, and 2021 with remaining amortization periods ranging from one to five years. However, when a plan change reduces the benefit obligation, existing positive prior service costs are reduced or eliminated starting with the earliest established before a new prior service credit base is established. Asset Method . TVA's asset method calculates a market-related value of assets ("MRVA") that recognizes realized and unrealized investment gains and losses over a three-year smoothing period to decrease the volatility of annual net periodic pension benefit costs. The MRVA is used to determine the expected return on plan assets, a component of net periodic pension benefit cost. The difference in the expected return on the MRVA and the actual return on the fair value on plan assets is recognized as an actuarial (gain)/loss in the pension benefit obligation at September 30. However, the MRVA has no impact on the fair value of plan assets measured at September 30.

Revenue (Policies)

Revenue (Policies)	12 Months Ended
	Sep. 30, 2024
Revenue from Contract with Customer [Abstract]
Revenues	Revenues TVA recognizes revenue from contracts with customers to depict the transfer of goods or services to customers in an amount to which the entity expects to be entitled in exchange for those goods or services. For the generation and transmission of electricity, this is generally at the time the power is delivered to a metered customer delivery point for the customer's consumption or distribution. As a result, revenues from power sales are recorded as electricity is delivered to customers. In addition to power sales invoiced and recorded during the month, TVA accrues estimated unbilled revenues for power sales provided to five customers whose billing date occurs prior to the end of the month. Exchange power sales are presented in the accompanying Consolidated Statements of Operations as a component of sales of electricity. Exchange power sales are sales of excess power after meeting TVA native load and directly served requirements. Native load refers to the customers on whose behalf a company, by statute, franchise, regulatory requirement, or contract, has undertaken an obligation to serve. TVA engages in other arrangements in addition to power sales. Certain other revenue from activities related to TVA's overall mission is recorded in Other revenue. Revenues that are not related to the overall mission are recorded in Other income, net.

Plant Closures (Policies)

Plant Closures (Policies)	12 Months Ended
	Sep. 30, 2024
Plant Closure [Abstract]
Plant Retirement and Abandonment, Policy [Policy Text Block]	Background TVA must continuously evaluate all generating assets to ensure an optimal energy portfolio that provides safe, clean, and reliable power while maintaining flexibility and fiscal responsibility to the people of the Tennessee Valley. Based on results of assessments presented to the TVA Board in 2019, the retirement of Bull Run Fossil Plant ("Bull Run") by December 2023 was approved, and as of September 30, 2023, the facility was retired. In January 2023, TVA issued its Record of Decision to retire two coal-fired units at Cumberland Fossil Plant ("Cumberland") by the end of CY 2026 and CY 2028. In April 2024, TVA issued its Record of Decision to retire the nine coal-fired units at Kingston Fossil Plant ("Kingston") by CY 2027. In addition, TVA is evaluating the impact of retiring the balance of the coal-fired fleet by 2035, and that evaluation includes environmental reviews, public input, and TVA Board approval. Financial Impact TVA's policy is to adjust depreciation rates to reflect the most current assumptions, ensuring units will be fully depreciated by the applicable retirement dates. As a result of TVA's decision to accelerate the retirement of Bull Run, TVA has recognized a cumulative $659 million of accelerated depreciation since the second quarter of 2019 through September 30, 2023. Of this amount, $177 million and $140 million were recognized for the years ended September 30, 2023, and 2022, respectively. TVA's decision to retire the two units at Cumberland is estimated to result in approximately $16 million of additional depreciation quarterly, which does not include any potential impact from additions or retirements to net completed plant. The cumulative impact approximates $112 million of additional depreciation since January 2023, related to this decision. In addition, TVA's decision to retire the nine units at Kingston is estimated to result in approximately $9 million of additional depreciation quarterly, which does not include any potential impact from additions or retirements to net completed plant. The cumulative impact approximates $18 million of additional depreciation since April 2024, related to this decision. TVA also recognized $15 million, $14 million, and $22 million in Operating and maintenance expense related to additional inventory reserves and project write-offs for the coal-fired fleet, including Kingston, Cumberland, and Bull Run, for the years ended September 30, 2024, 2023, and 2022, respectively.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies [Table Text Block]	12 Months Ended
	Sep. 30, 2024
Accounting Policies [Abstract]
Property, Plant, and Equipment Depreciation Rates	Average depreciation rates by asset class are as follows: Property, Plant, and Equipment Depreciation Rates At September 30 2024 2023 2022 Asset Class Nuclear 2.71 2.73 2.72 Coal-fired (1) 4.13 4.98 4.27 Hydroelectric 1.83 1.82 1.85 Gas and oil-fired 3.31 3.17 3.38 Transmission 1.52 1.52 1.51 Other 4.98 4.43 3.64
Schedule of Cash and Cash Equivalents	The following table provides a reconciliation of cash, cash equivalents, and restricted cash reported on the Consolidated Balance Sheets and Consolidated Statements of Cash Flows: Cash, Cash Equivalents, and Restricted Cash At September 30 (in millions) 2024 2023 Cash and cash equivalents $ 502 $ 501 Restricted cash and cash equivalents included in Other long-term assets 21 20 Total cash, cash equivalents, and restricted cash $ 523 $ 521

Accounts Receivable, Net Accoun

Accounts Receivable, Net Accounts Receivable, Net (Tables)	12 Months Ended
	Sep. 30, 2024
Accounts Receivable, after Allowance for Credit Loss [Abstract]
Accounts Receivable, Net	Accounts receivable primarily consist of amounts due from customers for power sales. The table below summarizes the types and amounts of TVA's accounts receivable: Accounts Receivable, Net At September 30 (in millions) 2024 2023 Power receivables $ 1,683 $ 1,627 Other receivables 118 118 Accounts receivable, net (1) $ 1,801 $ 1,745 Note (1) Allowance for uncollectible accounts was less than $1 million at both September 30, 2024 and 2023, and therefore is not represented in the table above.

Inventories, Net Inventories, N

Inventories, Net Inventories, Net (Tables)	12 Months Ended
	Sep. 30, 2024
Inventory, Net [Abstract]
Inventories, Net	The table below summarizes the types and amounts of TVA's inventories: Inventories, Net At September 30 (in millions) 2024 2023 Materials and supplies inventory $ 931 $ 849 Fuel inventory 286 313 Renewable energy certificates/emissions allowance inventory, net 11 15 Allowance for inventory obsolescence (73) (69) Inventories, net $ 1,155 $ 1,108

Deferred Costs, Capitalized, _4

Deferred Costs, Capitalized, Prepaid, and Other Assets (Tables)	12 Months Ended
	Sep. 30, 2024
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Schedule of Other Current Assets	Other current assets consisted of the following: Other Current Assets At September 30 (in millions) 2024 2023 (1) Inventory work-in-progress $ 41 $ 28 Prepaid software maintenance 22 18 Prepaid insurance 19 16 Prepaid cloud assets 13 7 Current portion of prepaid long-term service agreements 7 25 Commodity contract derivative assets 5 21 Other 13 19 Other current assets $ 120 $ 134 Note (1) At September 30, 2023, $7 million previously classified as Other (a component of Other current assets) has been reclassified to Prepaid cloud assets (a component of Other current assets) to conform to current year presentation.

Net Completed Plant Net Complet

Net Completed Plant Net Completed Plant (Tables)	12 Months Ended
	Sep. 30, 2024
Property, Plant and Equipment, Net, by Type [Abstract]
Net Completed Plant	Net completed plant consisted of the following: Net Completed Plant At September 30 (in millions) 2024 2023 Cost Accumulated Depreciation Cost Accumulated Depreciation Net Nuclear $ 26,800 $ 14,149 $ 12,651 $ 26,803 $ 13,557 $ 13,246 Coal-fired (1) 20,177 16,635 3,542 18,525 14,464 4,061 Gas and oil-fired 7,051 2,112 4,939 6,663 2,057 4,606 Transmission 9,964 3,450 6,514 9,375 3,359 6,016 Hydroelectric 4,307 1,288 3,019 4,109 1,241 2,868 Other electrical plant 1,763 737 1,026 1,798 780 1,018 Multipurpose dams 900 413 487 900 404 496 Other stewardship 27 9 18 26 9 17 Total $ 70,989 $ 38,793 $ 32,196 $ 68,199 $ 35,871 $ 32,328 Note (1) TVA recognized accelerated depreciation as a result of the decision to idle or retire certain units and the potential retirement of the remainder of the coal-fired fleet by 2035. See Note 7 — Plant Closures

Other Long-Term Assets (Tables)

Other Long-Term Assets (Tables)	12 Months Ended
	Sep. 30, 2024
Assets, Noncurrent [Abstract]
Other Long-Term Assets	The table below summarizes the types and amounts of TVA's other long-term assets: Other Long-Term Assets At September 30 (in millions) 2024 2023 (1) Loans and other long-term receivables, net $ 84 $ 97 Prepaid long-term service agreements 62 64 EnergyRight ® receivables, net 44 47 Cloud assets 35 15 Prepaid capital assets 29 28 Commodity contract derivative assets 2 12 Other 88 67 Total other long-term assets $ 344 $ 330 Note (1) At September 30, 2023, $15 million previously classified as Other (a component of Other long-term assets) has been reclassified to Cloud assets (a component of Other long-term assets) to conform to current year presentation.

Regulatory Assets and Liabili_2

Regulatory Assets and Liabilities Regulatory Assets and Liabilities (Tables)	12 Months Ended
	Sep. 30, 2024
Regulatory Assets and Liabilities Disclosure [Abstract]
Regulatory Assets and Liabilities	Components of regulatory assets and regulatory liabilities are summarized in the table below. Regulatory Assets and Liabilities At September 30 (in millions) 2024 2023 Current regulatory assets Unrealized losses on commodity derivatives $ 102 $ 136 Unrealized losses on interest rate derivatives 54 31 Fuel cost adjustment receivable 35 11 Total current regulatory assets 191 178 Non-current regulatory assets Non-nuclear decommissioning costs 6,187 2,922 Retirement benefit plans deferred costs 1,979 1,440 Unrealized losses on interest rate derivatives 447 272 Nuclear decommissioning costs 362 728 Environmental compliance and remediation costs 215 — Unrealized losses on commodity derivatives 64 52 Other non-current regulatory assets 154 152 Total non-current regulatory assets 9,408 5,566 Total regulatory assets $ 9,599 $ 5,744 Current regulatory liabilities Fuel cost adjustment tax equivalents $ 169 $ 201 Unrealized gains on commodity derivatives 5 21 Total current regulatory liabilities 174 222 Non-current regulatory liabilities Retirement benefit plans deferred credits 81 95 Unrealized gains on commodity derivatives 2 12 Total non-current regulatory liabilities 83 107 Total regulatory liabilities $ 257 $ 329

Asset Retirement Obligations _2

Asset Retirement Obligations Asset Retirement Obligations (Tables)	12 Months Ended
	Sep. 30, 2024
Asset Retirement Obligation Disclosure [Abstract]
Asset Retirement Obligation Activity	Asset Retirement Obligation Activity (in millions) Nuclear Non-Nuclear Total Balance at September 30, 2022 $ 3,643 $ 3,519 $ 7,162 Settlements (8) (271) (279) Revisions in estimate (non-cash) 7 362 369 Accretion (recorded as regulatory asset) 166 71 237 Balance at September 30, 2023 3,808 3,681 7,489 (1) Settlements (4) (253) (257) Revisions in estimate (non-cash) (160) 292 132 Additional obligations (non-cash) — 3,136 3,136 Accretion (recorded as regulatory asset) 170 136 306 Balance at September 30, 2024 $ 3,814 $ 6,992 $ 10,806 (1) Note (1) Includes $283 million and $272 million at September 30, 2024 and 2023, respectively, in Current liabilities.

Other Long-Term Liabilities Oth

Other Long-Term Liabilities Other Long-Term Liabilities (Tables)	12 Months Ended
	Sep. 30, 2024
Other Liabilities, Noncurrent [Abstract]
Other Long-Term Liabilities	The table below summarizes the types and amounts of Other long-term liabilities: Other Long-Term Liabilities At September 30 (in millions) 2024 2023 (1) Interest rate swap liabilities $ 792 $ 627 Environmental compliance and remediation costs 212 — Long-term project cost accruals 140 10 Currency swap liabilities 109 131 Operating lease liabilities 88 93 Commodity contract derivative liabilities 64 52 Advances for construction 55 56 EnergyRight ® financing obligation 52 55 Long-term deferred compensation 50 41 Long-term deferred revenue 48 45 Other 102 101 Total other long-term liabilities $ 1,712 $ 1,211 Note

Debt and Other Obligations Debt

Debt and Other Obligations Debt and Other Obligations (Tables)	12 Months Ended
	Sep. 30, 2024
Debt and Other Obligations [Abstract]
Schedule of short-term borrowings	The following table provides information regarding TVA's short-term borrowings: Short-Term Borrowings At September 30 2024 2023 Gross amount outstanding - discount notes (in millions) $ 1,168 $ 432 Weighted average interest rate - discount notes 4.76 % 5.29 %
Debt Securities Activity	The table below summarizes the long-term debt securities activity for the years ended September 30, 2024 and 2023. Debt Securities Activity For the years ended September 30 (in millions) 2024 2023 Issues 2023 Series A (1) $ — $ 1,000 2024 Series A (2) 1,000 — Discount on debt issues (9) (8) Total $ 991 $ 992 Redemptions/Maturities (3) 2009 Series B $ 22 $ 29 2014 Series A 1,000 — Total redemptions/maturities of power bonds 1,022 29 Debt of variable interest entities 35 39 Total redemptions/maturities of debt $ 1,057 $ 68 Notes (1) The 2023 Series A Bonds were issued at 99.187 percent of par. (2) The 2024 Series A Bonds were issued at 99.109 percent of par. (3) All redemptions were at 100 percent of par.
Debt Outstanding	Total debt outstanding at September 30, 2024 and 2023, consisted of the following: Short-Term Debt At September 30 (in millions) CUSIP or Other Identifier Maturity 2024 2023 Short-term debt, net of discounts $ 1,167 $ 432 Current maturities of long-term debt of VIEs issued at par 37 35 Current maturities of power bonds issued at par 880591ER9 9/15/2024 2.875% — 1,000 880591EF5 12/15/2024 3.770% 1 1 880591EW8 5/15/2025 0.750% 1,000 — 880591EF5 6/15/2025 3.770% 21 21 Total current maturities of power bonds issued at par 1,022 1,022 Total current debt outstanding, net $ 2,226 $ 1,489 Long-Term Debt At September 30 (in millions) CUSIP or Other Identifier Maturity Coupon 2024 Par 2023 Par Stock Exchange Listings 880591EW8 5/15/2025 0.750% $ — $ 1,000 New York 880591CJ9 11/1/2025 6.750% 1,350 1,350 New York, Hong Kong, Luxembourg, Singapore 880591EU2 2/1/2027 2.875% 1,000 1,000 New York 880591EZ1 3/15/2028 3.875% 1,000 1,000 New York 880591300 (1) 6/1/2028 2.134% 256 256 New York 880591409 (1) 5/1/2029 2.216% 208 208 New York 880591DM1 5/1/2030 7.125% 1,000 1,000 New York, Luxembourg 880591EX6 9/15/2031 1.500% 500 500 New York 880591DP4 6/7/2032 6.587% (2) 335 (3) 305 (3) New York, Luxembourg 880591DV1 7/15/2033 4.700% 472 472 New York, Luxembourg 880591EF5 6/15/2034 3.770% 116 139 None 880591FB3 8/1/2034 4.375% 1,000 — New York 880591DX7 6/15/2035 4.650% 436 436 New York 880591CK6 4/1/2036 5.980% 121 121 New York 880591CS9 4/1/2036 5.880% 1,500 1,500 New York 880591CP5 1/15/2038 6.150% 1,000 1,000 New York 880591ED0 6/15/2038 5.500% 500 500 New York 880591EH1 9/15/2039 5.250% 2,000 2,000 New York 880591EP3 12/15/2042 3.500% 1,000 1,000 New York 880591DU3 6/7/2043 4.962% (2) 201 (3) 183 (3) New York, Luxembourg 880591EB4 1/15/2048 4.875% 500 500 New York, Luxembourg 880591EY4 9/15/2052 4.250% 500 500 New York 880591DZ2 4/1/2056 5.375% 1,000 1,000 New York 880591EJ7 9/15/2060 4.625% 1,000 1,000 New York 880591ES7 9/15/2065 4.250% 1,000 1,000 New York Subtotal 17,995 17,970 Unamortized discounts, premiums, issue costs, and other (128) (126) Total long-term outstanding power bonds, net 17,867 17,844 Long-term debt of VIEs, net 897 933 Total long-term debt, net $ 18,764 $ 18,777 Notes (1) TVA PARRS, CUSIP numbers 880591300 and 880591409, may be redeemed under certain conditions. See Put Options above. (2) The coupon rate represents TVA's effective interest rate.
Maturities Due in the Year Ending September 30	Maturities Due in the Year Ending September 30 (in millions) 2025 2026 2027 2028 2029 Thereafter Total Long-term power bonds including current maturities (1) $ 1,022 $ 1,370 $ 1,020 $ 1,272 $ 220 $ 14,175 $ 19,079 Short-term debt net of discounts 1,167 — — — — — 1,167 Notes (1) Long-term power bonds do not include non-cash items of foreign currency exchange gain of $62 million, unamortized debt issue costs of $41 million, or net discount on sale of Bonds of $87 million.
Summary of Long-Term Credit Facilities	The following table provides additional information regarding TVA's funding available under the four long-term revolving credit facilities: Summary of Long-Term Credit Facilities At September 30, 2024 (in millions) Maturity Date Facility Limit Letters of Credit Outstanding Cash Borrowings Availability March 2026 $ 150 $ 38 $ — $ 112 September 2026 1,000 134 — 866 March 2027 1,000 180 — 820 February 2028 500 214 — 286 Total $ 2,650 $ 566 $ — $ 2,084

Risk Management Activities an_2

Risk Management Activities and Derivative Transactions Risk Management Activities and Derivative Transactions (Tables)	12 Months Ended
	Sep. 30, 2024
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Summary of Derivative Instruments That Receive Hedge Accounting Treatment	The following tables summarize the accounting treatment that certain of TVA's financial derivative transactions receive: Summary of Derivative Instruments That Receive Hedge Accounting Treatment (part 1) Amount of Mark-to-Market Gain (Loss) Recognized in Accumulated Other Comprehensive Income (Loss) For the years ended September 30 (in millions) Derivatives in Cash Flow Hedging Relationship Objective of Hedge Transaction Accounting for Derivative 2024 2023 Currency swaps To protect against changes in cash flows caused by changes in foreign currency exchange rates (exchange rate risk) Unrealized gains and losses are recorded in AOCI and reclassified to Interest expense to the extent they are offset by gains and losses on the hedged transaction $ 25 $ 99 Summary of Derivative Instruments That Receive Hedge Accounting Treatment (part 2) (1) Amount of Gain (Loss) Reclassified from Accumulated Other Comprehensive Income (Loss) to Interest Expense For the years ended September 30 (in millions) Derivatives in Cash Flow Hedging Relationship 2024 2023 Currency swaps $ 48 $ 42 Note (1) There were no amounts excluded from effectiveness testing for any of the periods presented. Based on forecasted foreign currency exchange rates, TVA expects to reclassify approximately $1 million of gains from AOCI to Interest expense within the next 12 months to offset amounts anticipated to be recorded in Interest expense related to the forecasted exchange loss on the debt.
Summary of Derivative Instruments That Do Not Receive Hedge Accounting Treatment	Summary of Derivative Instruments That Do Not Receive Hedge Accounting Treatment Amount of Gain (Loss) Recognized in Income on Derivatives (1) For the years ended September 30 (in millions) Derivative Type Objective of Derivative Accounting for Derivative Instrument 2024 2023 Interest rate swaps To fix short-term debt variable rate to a fixed rate (interest rate risk) Mark-to-market gains and losses are recorded as regulatory liabilities and assets, respectively Realized gains and losses are recognized in Interest expense when incurred during the settlement period and are presented in operating cash flow $ (31) $ (45) Commodity derivatives To protect against fluctuations in market prices of purchased commodities (price risk) Mark-to-market gains and losses are recorded as regulatory liabilities and assets, respectively Realized gains and losses are recognized in Fuel expense or Purchased power expense as the contracts settle to match the delivery period of the underlying commodity (2) (295) (348) Notes (1) All of TVA's derivative instruments that do not receive hedge accounting treatment have unrealized gains (losses) that would otherwise be recognized in income but instead are deferred as regulatory liabilities and assets. As such, there were no related gains (losses) recognized in income for these unrealized gains (losses) for the years ended September 30, 2024 and 2023. (2) Of the amount recognized in 2024, $245 million and $50 million were reported in Fuel expense and Purchased power expense, respectively. Of the amount recognized in 2023, $301 million and $47 million were reported in Fuel expense and Purchased power expense, respectively.
Fair Values of TVA Derivatives	Fair Values of TVA Derivatives At September 30 (in millions) 2024 2023 Derivatives That Receive Hedge Accounting Treatment: Balance Balance Sheet Presentation Balance Balance Sheet Presentation Currency swaps £250 million Sterling $ (49) Accounts payable and accrued liabilities $(4); Other long-term liabilities $(45) $ (72) Accounts payable and accrued liabilities $(6); Other long-term liabilities $(66) £150 million Sterling (67) Accounts payable and accrued liabilities $(3); Other long-term liabilities $(64) (69) Accounts payable and accrued liabilities $(4); Other long-term liabilities $(65) Derivatives That Do Not Receive Hedge Accounting Treatment: Balance Balance Sheet Presentation Balance Balance Sheet Presentation Interest rate swaps $1.0 billion notional $ (622) Accounts payable and accrued liabilities $(10); Accrued interest $(26); Other long-term liabilities $(586) $ (499) Other current assets $1; Accrued interest $(27); Other long-term liabilities $(473) $476 million notional (218) Accounts payable and accrued liabilities $(3); Accrued interest $(9); Other long-term liabilities $(206) (159) Other current assets $3; Accrued interest $(8); Other long-term liabilities $(154) Commodity contract derivatives 2 Other current assets $5; Other long-term assets $2; Accounts payable and accrued liabilities $(3); Other long-term liabilities $(2) 31 Other current assets $21; Other long-term assets $12; Accounts payable and accrued liabilities $(1); Other long-term liabilities $(1) Commodity derivatives under the FHP (161) Accounts payable and accrued liabilities $(99); Other long-term liabilities $(62) (186) Accounts payable and accrued liabilities $(135); Other long-term liabilities $(51)
Currency Swaps Outstanding	TVA had the following currency swaps outstanding at September 30, 2024: Currency Swaps Outstanding Effective Date of Currency Swap Contract Associated TVA Bond Issues Currency Exposure Expiration Date of Swap Overall Effective 2001 £250 million 2032 6.587% 2003 £150 million 2043 4.962%
Commodity Contract Derivatives	Commodity Contract Derivatives At September 30 2024 2023 Number of Contracts Notional Amount Fair Value (MtM) Number of Contracts Notional Amount Fair Value ( MtM ) (in millions) Natural gas contract derivatives 45 321 million mmBtu $ 2 54 318 million mmBtu $ 31
Offsetting Assets and Liabilities	The amounts of TVA's derivative instruments as reported on the Consolidated Balance Sheets are shown in the table below: Derivative Assets and Liabilities (1) At September 30 (in millions) 2024 2023 Assets Interest rate swaps $ — $ 4 Commodity contract derivatives 7 33 Commodity derivatives under the FHP (2) — — Total derivatives subject to master netting or similar arrangement $ 7 $ 37 Liabilities Currency swaps $ 116 $ 141 Interest rate swaps (3) 840 662 Commodity contract derivatives 5 2 Commodity derivatives under the FHP (2) 161 186 Total derivatives subject to master netting or similar arrangement $ 1,122 $ 991 Notes (1) Offsetting amounts include counterparty netting of derivative contracts. Except as discussed below, there were no other material offsetting amounts on TVA's Consolidated Balance Sheets at either September 30, 2024 or 2023. (2) At September 30, 2024, the gross derivative asset and gross derivative liability was $4 million and $165 million, respectively, with offsetting amounts for each totaling $4 million. At September 30, 2023, the gross derivative asset and gross derivative liability were $26 million and $212 million, respectively, with offsetting amounts for each totaling $26 million.
Schedule of Derivative Instruments Commodity Contracts under FHP	Commodity Derivatives under Financial Hedging Program (1) At September 30 2024 2023 Number of Contracts Notional Amount Fair Value (MtM) (in millions) Number of Contracts Notional Amount Fair Value (MtM) (in millions) Natural gas swap contracts 126 230 million mmBtu $ (161) 221 388 million mmBtu $ (186) Note (1) Fair value amounts presented are based on the net commodity position with the counterparty. Notional amounts disclosed represent the net value of contractual amounts.

Fair Value Measurements (Tables

Fair Value Measurements (Tables) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023
Fair Value Disclosures [Abstract]
Transfers Accounted for as Secured Borrowings, Assets, Carrying Amount	$ 56	$ 55
Valuation Techniques	The measurement of fair value results in classification into a hierarchy by the inputs used to determine the fair value as follows: Level 1 — Unadjusted quoted prices in active markets accessible by the reporting entity for identical assets or liabilities. Active markets are those in which transactions for the asset or liability occur with sufficient frequency and volume to provide pricing. Level 2 — Pricing inputs other than quoted market prices included in Level 1 that are based on observable market data and that are directly or indirectly observable for substantially the full term of the asset or liability. These include quoted market prices for similar assets or liabilities, quoted market prices for identical or similar assets in markets that are not active, adjusted quoted market prices, inputs from observable data such as interest rate and yield curves, volatilities and default rates observable at commonly quoted intervals, and inputs derived from observable market data by correlation or other means. Level 3 — Pricing inputs that are unobservable, or less observable, from objective sources. Unobservable inputs are only to be used to the extent observable inputs are not available. These inputs maintain the concept of an exit price from the perspective of a market participant and should reflect assumptions of other market participants. An entity should consider all market participant assumptions that are available without unreasonable cost and effort. These are given the lowest priority and are generally used in internally developed methodologies to generate management's best estimate of the fair value when no observable market data is available.
Unrealized Investment Gains (Losses)	TVA recorded unrealized gains and losses related to its equity and trading debt securities held during each period as follows: Unrealized Investment Gains (Losses) (1) For the years ended September 30 (in millions) Fund Financial Statement Presentation 2024 2023 NDT Regulatory assets (2) $ 324 $ 162 ART Regulatory assets (3) 171 96 SERP Other income (expense) 14 6 DCP Other income (expense) 2 1 Notes (1) The unrealized losses for the RP were less than $1 million for both the years ended September 30, 2024 and 2023 and therefore were not represented in the table above. (2) Includes $93 million of unrealized gains and $27 million of unrealized gains related to NDT equity securities (excluding commingled funds) for the years ended September 30, 2024 and 2023, respectively.
Fair Value Measurements		Fair Value Measurements At September 30, 2024 (in millions) Quoted Prices in Active Significant Other Significant Total Assets Investments Equity securities $ 770 $ — $ — $ 770 Government debt securities (1)(2) 400 57 — 457 Corporate debt securities (4) — 378 — 378 Mortgage and asset-backed securities — 43 — 43 Institutional mutual funds 342 — — 342 Forward debt securities contracts — 11 — 11 Cash equivalents and other short-term investments (2)(3) 95 183 — 278 Private equity funds measured at net asset value (5) — — — 738 Private real asset funds measured at net asset value (5) — — — 432 Private credit funds measured at net asset value (5) — — — 219 Commingled funds measured at net asset value (5) — — — 1,300 Total investments 1,607 672 — 4,968 Interest rate swaps — — — — Commodity contract derivatives — 7 — 7 Total $ 1,607 $ 679 $ — $ 4,975 Quoted Prices in Active Markets for Identical Liabilities Significant Other Significant Total Liabilities Currency swaps (6) $ — $ 116 $ — $ 116 Interest rate swaps — 840 — 840 Commodity contract derivatives — 5 — 5 Commodity derivatives under the FHP — 161 — 161 Total $ — $ 1,122 $ — $ 1,122 Notes (1) Includes obligations of government-sponsored entities. (2) There are $400 million of U.S. Treasury securities in Level 1 Government debt securities and $95 million of U.S. Treasury securities in Level 1 Cash equivalents and other short-term investments for a total of $495 million of U.S. Treasury securities within Level 1 of the fair value hierarchy. (3) Includes $78 million net payables (interest receivable, dividends receivable, receivables for investments sold, and payables for investments purchased), and $174 million of repurchase agreements in Level 2 Cash equivalents and other short-term investments. (4) Includes both U.S. and foreign debt. (5) Certain investments that are measured at fair value using the NAV or its equivalent (alternative investments) have not been categorized in the fair value hierarchy. The inputs to these fair value measurements include underlying NAVs, discounted cash flow valuations, comparable market valuations, estimated benchmark yields, and adjustments for currency, credit, liquidity, and other risks. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the amounts presented on the Consolidated Balance Sheets. (6) TVA records currency swaps net of cash collateral received from or paid to the counterparty, to the extent such amount is not recorded in Accounts payable and accrued liabilities. See Note 15 — Risk Management Activities and Derivative Transactions — Offsetting of Derivative Assets and Liabilities . Fair Value Measurements At September 30, 2023 (in millions) Quoted Prices in Active Significant Other Significant Total Assets Investments Equity securities $ 608 $ — $ — $ 608 Government debt securities (1)(2) 287 60 — 347 Corporate debt securities (4) — 300 — 300 Mortgage and asset-backed securities — 36 — 36 Institutional mutual funds 288 — — 288 Forward debt securities contracts — 11 — 11 Cash equivalents and other short-term investments (2)(3) 104 166 — 270 Private equity funds measured at net asset value (5) — — — 583 Private real asset funds measured at net asset value (5) — — — 387 Private credit funds measured at net asset value (5) — — — 158 Commingled funds measured at net asset value (5) — — — 1,135 Total investments 1,287 573 — 4,123 Interest rate swaps — 4 — 4 Commodity contract derivatives — 33 — 33 Total $ 1,287 $ 610 $ — $ 4,160 Quoted Prices in Active Markets for Identical Liabilities Significant Other Significant Total Liabilities Currency swaps (6) $ — $ 141 $ — $ 141 Interest rate swaps — 662 — 662 Commodity contract derivatives — 2 — 2 Commodity derivatives under the FHP — 186 — 186 Total $ — $ 991 $ — $ 991 Notes (1) Includes obligations of government-sponsored entities. (2) There are $287 million of U.S. Treasury securities in Level 1 Government debt securities and $104 million of U.S. Treasury securities in Level 1 Cash equivalents and other short-term investments for a total of $391 million of U.S. Treasury securities within Level 1 of the fair value hierarchy. (3) Includes $73 million net payables (interest receivable, dividends receivable, receivables for investments sold, and payables for investments purchased). (4) Includes both U.S. and foreign debt. (5) Certain investments that are measured at fair value using the NAV or its equivalent (alternative investments) have not been categorized in the fair value hierarchy. The inputs to these fair value measurements include underlying NAVs, discounted cash flow valuations, comparable market valuations, estimated benchmark yields, and adjustments for currency, credit, liquidity, and other risks. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the amounts presented on the Consolidated Balance Sheets. (6) TVA records currency swaps net of cash collateral received from or paid to the counterparty, to the extent such amount is not recorded in Accounts payable and accrued liabilities. See Note 15 — Risk Management Activities and Derivative Transactions — Offsetting of Derivative Assets and Liabilities .
Estimated Values of Financial Instruments Not Recorded at Fair Value	The estimated values of TVA's financial instruments not recorded at fair value at September 30, 2024 and 2023, were as follows: Estimated Values of Financial Instruments Not Recorded at Fair Value (in millions) At September 30, 2024 At September 30, 2023 Valuation Classification Carrying Fair Carrying Fair EnergyRight ® receivables, net (including current portion) Level 2 $ 56 $ 56 $ 59 $ 55 Loans and other long-term receivables, net (including current portion) Level 2 105 99 104 96 EnergyRight ® financing obligations (including current portion) Level 2 66 74 69 81 Unfunded loan commitments Level 2 — — — 1 Membership interests of VIEs subject to mandatory redemption (including current portion) Level 2 17 19 18 19 Long-term outstanding power bonds, net (including current maturities) Level 2 18,889 19,416 18,866 17,963 Long-term debt of VIEs, net (including current maturities) Level 2 934 966 968 927

Other Income (Expense), Net Oth

Other Income (Expense), Net Other Income (Expense), Net (Tables)	12 Months Ended
	Sep. 30, 2024
Other Income and Expenses [Abstract]
Other Income (Expense), Net	Income and expenses not related to TVA's operating activities are summarized in the following table: Other Income, Net For the years ended September 30 (in millions) 2024 2023 2022 Interest income $ 42 $ 34 $ 15 External services 17 15 16 Gains (losses) on investments 23 13 (17) Miscellaneous (11) (1) (7) Total other income, net $ 71 $ 61 $ 7

Benefit Plans Benefit Plans (Ta

Benefit Plans Benefit Plans (Tables)	12 Months Ended
	Sep. 30, 2024
Retirement Benefits [Abstract]
Obligations and Funded Status	The changes in plan obligations, assets, and funded status for the years ended September 30, 2024 and 2023, were as follows: Obligations and Funded Status For the years ended September 30 (in millions) 867,300,000 Pension Benefits Other Post-Retirement Benefits 812,900,000 2024 2023 2024 2023 Change in benefit obligation Benefit obligation at beginning of year $ 10,099 $ 10,536 $ 347 $ 388 Service cost 29 32 11 10 Interest cost 579 568 21 18 Plan participants' contributions 3 4 — — Collections (1) — — 12 13 Actuarial (gain) loss 1,059 (284) (4) (44) Net transfers (to) from variable fund/401(k) plan 5 4 — — Expenses paid (6) (7) — — Benefits paid (766) (754) (34) (38) Benefit obligation at end of year 11,002 10,099 353 347 Change in plan assets Fair value of net plan assets at beginning of year 8,129 8,094 — — Actual return on plan assets 1,004 482 — — Plan participants' contributions 3 4 — — Collections (1) — — 12 13 Net transfers (to) from variable fund/401(k) plan 5 4 — — Employer contributions 304 306 22 25 Expenses paid (6) (7) — — Benefits paid (766) (754) (34) (38) Fair value of net plan assets at end of year 8,673 8,129 — — Funded status $ (2,329) $ (1,970) $ (353) $ (347) Note (1) Collections include retiree contributions as well as provider discounts and rebates.
Amounts Recognized on TVA's Consolidated Balance Sheets	Amounts related to these benefit plans recognized on TVA's Consolidated Balance Sheets consist of regulatory assets and liabilities that have not been recognized as components of net periodic benefit cost at September 30, 2024 and 2023, and the funded status of TVA's benefit plans, which are included in Accounts payable and accrued liabilities and Post-retirement and post-employment benefit obligations: Amounts Recognized on TVA's Consolidated Balance Sheets At September 30 (in millions) Pension Benefits Other Post-Retirement Benefits 2024 2023 2024 2023 Regulatory assets (liabilities) $ 1,979 $ 1,440 $ (81) $ (95) Accounts payable and accrued liabilities (6) (6) (20) (21) Pension and post-retirement benefit obligations (1) (2,323) (1,964) (333) (326) Note
Post-Retirement Benefit Costs Deferred as Regulatory Assets	Unrecognized amounts included in regulatory assets or liabilities yet to be recognized as components of accrued benefit cost at September 30, 2024 and 2023, consisted of the following: Post-Retirement Benefit Costs Deferred as Regulatory Assets (Liabilities) At September 30 (in millions) Pension Benefits Other Post-Retirement Benefits 2024 2023 2024 2023 Unrecognized prior service credit $ (247) $ (336) $ (42) $ (59) Unrecognized net loss (gain) 2,226 1,776 (39) (36) Total regulatory assets (liabilities) $ 1,979 $ 1,440 $ (81) $ (95)
Projected Benefit Obligations and Accumulated Benefit Obligations in Excess of Plan Assets	Information for the pension projected benefit obligation ("PBO") in excess of plan assets and other post-retirement accumulated postretirement benefit obligation ("APBO") has been disclosed in the Obligations and Funded Status table above. The following table provides the pension plan accumulated benefit obligation ("ABO") in excess of plan assets. The other post-retirement plans are unfunded or have no plan assets. Accumulated Benefit Obligations in Excess of Plan Assets At September 30 (in millions) 2024 2023 Accumulated benefit obligation $ 10,971 $ 10,069 Fair value of net plan assets 8,673 8,129
Components of Net Periodic Benefit Cost	The components of net periodic benefit cost for the years ended September 30, 2024, 2023, and 2022 were as follows: Components of Net Periodic Benefit Cost (1) For the years ended September 30 (in millions) Pension Benefits Other Post-Retirement Benefits 2024 2023 2022 2024 2023 2022 Service cost $ 29 $ 32 $ 53 $ 11 $ 10 $ 17 Interest cost 579 568 378 21 18 15 Expected return on plan assets (494) (492) (435) — — — Amortization of prior service credit (89) (88) (93) (17) (17) (17) Recognized net actuarial loss (gain) 99 135 392 (1) (2) 5 Total net periodic benefit cost as actuarially determined 124 155 295 14 9 20 Amount expensed due to actions of regulator — 77 13 — — — Net periodic benefit cost $ 124 $ 232 $ 308 $ 14 $ 9 $ 20
Sensitivity to Certain Changes in Pension Assumptions	The following chart reflects the sensitivity of pension cost to changes in certain actuarial assumptions: Sensitivity to Certain Changes in Pension Assumptions Actuarial Assumption Change in Assumption Impact on 2024 Pension Cost (in millions) Impact on 2024 Projected Benefit Obligation (in millions) Discount rate (0.25) % $ 11 $ 273 Rate of return on plan assets (0.25) % 19 N/A Cost of living adjustments 0.25 % 22 188
Asset Holdings and Fair Value Measurements	At September 30, 2024 and 2023, the asset holdings of TVARS included the following: Asset Holdings of TVARS Plan Assets at September 30 Asset Category Target Allocation 2024 2023 Growth assets 17 % 21 % 22 % Defensive growth assets 30 % 23 % 33 % Defensive assets 33 % 34 % 17 % Inflation-sensitive assets 20 % 22 % 28 % Total 100 % 100 % 100 % Fair Value Measurements The following table provides the fair value measurement amounts for assets held by TVARS at September 30, 2024: TVA Retirement System At September 30, 2024 (in millions) Total (1)(2) Quoted Prices in Active Markets for Identical Significant Other Significant Assets Equity securities $ 670 $ 668 $ — $ 2 Preferred securities 3 — 2 1 Debt securities Corporate debt securities 1,122 — 1,121 1 Mortgage and asset-backed securities 572 — 511 61 Debt securities issued by U.S. Treasury 543 543 — — Debt securities issued by foreign governments 19 — 19 — Debt securities issued by state/local governments 23 — 23 — Commingled funds measured at net asset value (3) Equity 245 — — — Debt 1,236 — — — Institutional mutual funds 180 180 — — Cash equivalents and other short-term investments 249 5 244 — Private credit funds measured at net asset value (3) 1,126 — — — Private equity funds measured at net asset value (3) 1,580 — — — Private real asset funds measured at net asset value (3) 1,150 — — — Securities lending collateral 235 — 235 — Derivatives Swaps 6 — 6 — Total assets $ 8,959 $ 1,396 $ 2,161 $ 65 Liabilities Derivatives Futures $ 1 $ 1 $ — $ — Swaps 3 — 3 — Total liabilities $ 4 $ 1 $ 3 $ — Notes (1) Excludes approximately $47 million in net payables associated with security purchases and sales and various other payables. (2) Excludes a $235 million payable for collateral on loaned securities in connection with TVARS's participation in securities lending programs. (3) Certain investments that are measured at fair value using the NAV or its equivalent ("alternative investments") have not been categorized in the fair value hierarchy. The inputs to these fair value measurements include underlying NAVs, discounted cash flow valuations, comparable market valuations, estimated benchmark yields, and adjustments for currency, credit, liquidity, and other risks. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the amounts presented on the Consolidated Balance Sheets as the fair value of net plan assets. The following table provides the fair value measurement amounts for assets held by TVARS at September 30, 2023: TVA Retirement System At September 30, 2023 (in millions) Total (1)(2) Quoted Prices in Active Markets for Identical Significant Other Significant Assets Equity securities $ 732 $ 731 $ — $ 1 Preferred securities 4 — 4 — Debt securities Corporate debt securities 1,109 — 1,107 2 Mortgage and asset-backed securities 616 — 561 55 Debt securities issued by U.S. Treasury 602 602 — — Debt securities issued by foreign governments 12 — 10 2 Debt securities issued by state/local governments 21 — 21 — Commingled funds measured at net asset value (3) Equity 360 — — — Debt 544 — — — Blended 101 — — — Institutional mutual funds 363 363 — — Cash equivalents and other short-term investments 315 51 264 — Private credit funds measured at net asset value (3) 694 — — — Private equity funds measured at net asset value (3) 1,769 — — — Private real asset funds measured at net asset value (3) 1,162 — — — Securities lending collateral 181 — 181 — Derivatives Futures 1 1 — — Swaps 17 — 17 — Foreign currency forward receivable 2 — 2 — Total assets $ 8,605 $ 1,748 $ 2,167 $ 60 Liabilities Derivatives Futures $ 5 $ 5 $ — $ — Swaps 26 — 26 — Options 1 1 — — Securities sold under agreements to repurchase 96 — 96 — Total liabilities $ 128 $ 6 $ 122 $ — Notes (1) Excludes approximately $167 million in net payables associated with security purchases and sales and various other payables. (2) Excludes a $181 million payable for collateral on loaned securities in connection with TVARS's participation in securities lending programs. (3) Certain investments that are measured at fair value using the NAV or its equivalent ("alternative investments") have not been categorized in the fair value hierarchy. The inputs to these fair value measurements include underlying NAVs, discounted cash flow valuations, comparable market valuations, estimated benchmark yields, and adjustments for currency, credit, liquidity, and other risks. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the amounts presented on the Consolidated Balance Sheets as the fair value of net plan assets.
Fair Value Measurements Using Significant Unobservable Inputs	The following table provides a reconciliation of beginning and ending balances of pension plan assets measured at fair value on a recurring basis where the determination of fair value includes significant unobservable inputs (Level 3): Fair Value Measurements Using Significant Unobservable Inputs (in millions) Fair Value Measurements Using Significant Unobservable Inputs (Level 3) Balance at September 30, 2022 $ 62 Net realized/unrealized gains (losses) 1 Purchases, sales, issuances, and settlements (net) 2 Transfers in and/or out of Level 3 (5) Balance at September 30, 2023 60 Net realized/unrealized gains (losses) 2 Purchases, sales, issuances, and settlements (net) 10 Transfers in and/or out of Level 3 (7) Balance at September 30, 2024 $ 65
Estimated Future Benefit Payments	Cash Flows Estimated Future Benefit Payments. The following table sets forth the estimated future benefit payments under the benefit plans. Estimated Future Benefits Payments At September 30, 2024 (in millions) Pension Benefits (1) Other Post-Retirement Benefits 2025 $ 820 $ 20 2026 821 19 2027 821 19 2028 819 19 2029 813 19 2030 - 2034 3,917 106 Note (1) Participants are assumed to receive the Fixed Fund in a lump sum in lieu of available annuity options allowed for certain grandfathered participants resulting in higher estimated pension benefits payments.
Amounts recognized on Consolidated Balance Sheets	Amounts Recognized on TVA's Consolidated Balance Sheets At September 30 (in millions) 2024 2023 Accounts payable and accrued liabilities $ 28 $ 29 Post-retirement and post-employment benefit obligations 230 237

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Sep. 30, 2024
Commitments and Contingencies Disclosure [Abstract]
Unfunded loan commitments	At September 30, 2024, TVA had no commitments under unfunded loan commitments for 2025 through 2029.

Related Parties Related Parties

Related Parties Related Parties (Tables)	12 Months Ended
	Sep. 30, 2024
Related Party Transactions [Abstract]
Related Party Transactions	Transactions with agencies of the federal government were as follows: Related Party Transactions At or for the years ended September 30 (in millions) 2024 2023 2022 Revenue from sales of electricity $ 118 $ 120 $ 134 Other income 273 282 296 Expenditures Operating expenses 241 234 228 Additions to property, plant, and equipment 12 8 11 Cash and cash equivalents 31 31 30 Accounts receivable, net 81 87 78 Investment funds 495 391 358 Long-term accounts receivable 35 38 43 Accounts payable and accrued liabilities 45 42 42 Long-term power bonds, net 3 1 1 Return on power program appropriation investment 7 6 4

Revenue (Tables)

Revenue (Tables)	12 Months Ended
	Sep. 30, 2024
Revenue from Contract with Customer [Abstract]
Revenues	Revenues TVA recognizes revenue from contracts with customers to depict the transfer of goods or services to customers in an amount to which the entity expects to be entitled in exchange for those goods or services. For the generation and transmission of electricity, this is generally at the time the power is delivered to a metered customer delivery point for the customer's consumption or distribution. As a result, revenues from power sales are recorded as electricity is delivered to customers. In addition to power sales invoiced and recorded during the month, TVA accrues estimated unbilled revenues for power sales provided to five customers whose billing date occurs prior to the end of the month. Exchange power sales are presented in the accompanying Consolidated Statements of Operations as a component of sales of electricity. Exchange power sales are sales of excess power after meeting TVA native load and directly served requirements. Native load refers to the customers on whose behalf a company, by statute, franchise, regulatory requirement, or contract, has undertaken an obligation to serve. TVA engages in other arrangements in addition to power sales. Certain other revenue from activities related to TVA's overall mission is recorded in Other revenue. Revenues that are not related to the overall mission are recorded in Other income, net.
Disaggregation of Revenue [Table Text Block]	TVA's operating revenues by state for each of the last three years are detailed in the table below: Operating Revenues By State For the years ended September 30 (in millions) 2024 2023 2022 Alabama $ 1,768 $ 1,731 $ 1,778 Georgia 295 284 299 Kentucky 776 773 821 Mississippi 1,150 1,146 1,182 North Carolina 89 89 87 Tennessee 7,998 7,819 8,137 Virginia 47 46 48 Subtotal 12,123 11,888 12,352 Off-system sales 8 14 19 Revenue capitalized during pre-commercial plant operations (1) (3) (3) — Revenue from sales of electricity 12,128 11,899 12,371 Other revenue 186 155 169 Total operating revenues $ 12,314 $ 12,054 $ 12,540 Note (1) Represents revenue capitalized during pre-commercial operations at Paradise CTs 5-7 in 2024 and Colbert CTs 9-11 in 2023.
Revenue from External Customers by Products and Services	TVA's operating revenues by customer type for each of the last three years are detailed in the table below: Operating Revenues by Customer Type For the years ended September 30 (in millions) 2024 2023 2022 Revenue from sales of electricity Local power companies $ 11,138 $ 10,903 $ 11,291 Industries directly served 868 864 926 Federal agencies and other 125 135 154 Revenue capitalized during pre-commercial plant operations (1) (3) (3) — Revenue from sales of electricity 12,128 11,899 12,371 Other revenue 186 155 169 Total operating revenues $ 12,314 $ 12,054 $ 12,540 Note (1) Represents revenue capitalized during pre-commercial operations at Paradise CTs 5-7 in 2024 and Colbert CTs 9-11 in 2023.
Schedule of Long-Term Contracts for Purchase of Electric Power	The number of LPCs by contract arrangement, the revenues derived from such arrangements for 2024, and the percentage those revenues comprised of TVA's total operating revenues for 2024, are summarized in the table below: TVA Local Power Company Contracts At or for the year ended September 30, 2024 Contract Arrangements (1) Number of LPCs Revenue from Sales of Electricity to LPCs Percentage of Total Operating Revenues 20-year termination notice 148 $ 9,621 78.1 % 5-year termination notice 5 1,517 12.3 % Total 153 $ 11,138 90.4 % Note (1) Ordinarily, the LPCs and TVA have the same termination notice period; however, in a contract with one of the LPCs with a five-year termination notice, TVA has a 10-year termination notice (which becomes a five-year termination notice if TVA loses its discretionary wholesale rate-setting authority). Certain LPCs have five-year termination notices or a shorter period if any act of Congress, court decision, or regulatory change requires or permits that election.

Leases (Table Text Block)

Leases (Table Text Block)	12 Months Ended
	Sep. 30, 2024
Leases [Abstract]
Amounts Recognized on Balance Sheets	The following table provides information regarding the presentation of leases on the Consolidated Balance Sheets: Amounts Recognized on TVA's Consolidated Balance Sheets At September 30 (in millions) 2024 2023 Assets Operating Operating lease assets, net of amortization $ 149 $ 177 Finance Finance leases 729 572 Total lease assets $ 878 $ 749 Liabilities Current Operating Accounts payable and accrued liabilities $ 63 $ 71 Finance Accounts payable and accrued liabilities 80 56 Non-current Operating Other long-term liabilities 88 93 Finance Finance lease liabilities 700 576 Total lease liabilities $ 931 $ 796
Amounts Recognized on Statements of Cash Flows	The following table contains additional information with respect to cash and non-cash activities related to leases: Amounts Recognized on TVA's Consolidated Statements of Cash Flows For the years ended September 30 (in millions) 2024 2023 2022 Operating cash flows for operating leases $ 78 $ 77 $ 57 Operating cash flows for finance leases 37 43 42 Financing cash flows for finance leases 76 56 60 Lease assets obtained in exchange for lease obligations (non-cash) Operating leases $ 115 $ 84 $ 43 Finance leases 230 3 —
Weighted Averages	TVA has certain finance leases under PPAs under which the present value of the minimum lease payments exceeds the fair value of the related lease asset at the date of measurement. This resulted in an interest rate that was higher than TVA's incremental borrowing rate. The weighted average remaining lease terms in years and the weighted average discount rate for TVA's operating and finance leases were as follows: Weighted Averages At September 30 2024 2023 Weighted average remaining lease terms Operating leases 4 years 3 years Finance leases (1) 9 years 10 years Weighted average discount rate (2) Operating leases 4.3% 4.1% Finance leases 17.6% 21.6% Note (1) One of TVA's finance leases includes an option period to extend, which TVA is reasonably certain to exercise. (2) The discount rate is calculated using the rate implicit in a lease if it is readily determinable. If the rate used by the lessor is not readily determinable, TVA uses its incremental borrowing rate as permitted by accounting guidance. The incremental borrowing rate is influenced by TVA's credit rating and lease term and as such may differ for individual leases, embedded leases, or portfolios of leased assets. .
Future Minimum Lease Payments	The following table presents maturities of lease liabilities and a reconciliation of the undiscounted cash flows to lease liabilities at September 30, 2024 : Future Minimum Lease Payments Minimum payments outstanding at September 30, 2024 (in millions) Operating leases 2025 $ 68 2026 34 2027 31 2028 18 2029 4 Thereafter 8 Minimum annual payments 163 Less: present value discount (12) Operating present value of net minimum lease payments $ 151 Finance leases 2025 $ 140 2026 139 2027 137 2028 133 2029 132 Thereafter 452 Minimum annual payments 1,133 Less: amount representing interest (353) Finance present value of net minimum lease payments $ 780
Lease, Cost	TVA's leases consist primarily of railcars, equipment, real estate/land, power generating facilities, and gas pipelines. TVA's leases have various terms and expiration dates remaining from less than one year to 22 years. The components of lease costs were as follows: Lease Costs For the years ended September 30 (in millions) 2024 2023 2022 Operating lease costs (1) $ 77 $ 69 $ 56 Variable lease costs (1)(5) 258 134 78 Short-term lease costs (1) 10 18 26 Finance lease costs Amortization of lease assets (2) 79 57 58 Interest on lease liabilities (3)(4) 37 43 42 Total finance lease costs 116 100 100 Total lease costs $ 461 $ 321 $ 260 Notes (1) Costs are included in Operating and maintenance expense, Fuel expense, Purchased power expense, and Tax equivalents expense on the Consolidated Statements of Operations. (2) Expense is included in Depreciation and amortization expense on the Consolidated Statements of Operations. (3) Expense is included in Interest expense on the Consolidated Statements of Operations. (4) Certain finance leases receive regulatory accounting treatment and are reclassified to Fuel expense and Purchased power expense. (5) Variable lease costs include costs related to variable payments that are based on energy production levels, which are allocated to expense based on the determination of lease and non-lease components associated with the underlying agreements.

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - General (Details) $ in Millions	12 Months Ended
	Sep. 30, 2024 USD ($) People	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)	Sep. 30, 2021 USD ($)	Sep. 30, 2014 USD ($)
Accounting Policies [Abstract]
Cash and Cash Equivalents, at Carrying Value	$ 502	$ 501
Reimbursements from DOE	284
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	523	521	$ 520	$ 518
Accounts receivable from DOE	13
Appropriation-investment power program	$ 258	258			$ 1,000
Population of Service Area [Line Items]
Population of service area | People	10,000,000
Cash and Cash Equivalents, at Carrying Value	$ 502	501
Restricted Cash and Cash Equivalents, Noncurrent	21	20
Accumulated depreciation	$ 38,793	$ 35,871

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Reclassificatons (Details) $ in Millions	Sep. 30, 2024 USD ($)
Reclassifications
Finance Lease, Liability	$ 780

Summary of Significant Accoun_6

Summary of Significant Accounting Policies - Allowance for Uncollectible Accounts (Details) - USD ($) $ in Millions	Sep. 30, 2024	Sep. 30, 2023
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, after Allowance for Credit Loss	$ 99	$ 96
Allowance for uncollectible accounts - receivables	1	1	[1]
Loans and Leases Receivable, Allowance	2	3
Reported Value Measurement
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, after Allowance for Credit Loss	$ 105	$ 104
[1]Allowance for uncollectible accounts was less than $1 million at both September 30, 2024 and 2023, and therefore is not represented in the table above.

Summary of Significant Accoun_7

Summary of Significant Accounting Policies - Property, Plant, and Equipment, and Depreciation (Details) - USD ($) $ in Millions	12 Months Ended			57 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023
Property, Plant, and Equipment, and Depreciation
Depreciation	$ 1,800	$ 1,900	$ 1,800
Composite depreciation rate for completed plant	2.92%	3.14%	2.98%
Reacquired Rights	$ 312	$ 324		$ 324
Amortization of Reacquired Rights	$ 11	10	$ 6
Capitalized software amortization period	7 years
Accelerated depreciation		177	$ 140	659
Accumulated Amortization of Reacquired Rights	$ 63	$ 52		$ 52
Amortization Reacquired Rights, Year 1	12
Amortization Reacquired Rights, Year 2	11
Amortization Reacquired Rights, Year 3	12
Amortization Reacquired Rights, Year 4	11
Amortization Reacquired Rights, Year 5	11
Amortization Reacquired Rights, Year Thereafter	255
Reimbursements from DOE	284
Accounts receivable from DOE	$ 13
Nuclear
Property, Plant, and Equipment, and Depreciation
Composite depreciation rate for completed plant	2.71%	2.73%	2.72%
Coal-fired
Property, Plant, and Equipment, and Depreciation
Composite depreciation rate for completed plant	4.13%	4.98%	4.27%
Hydroelectric
Property, Plant, and Equipment, and Depreciation
Composite depreciation rate for completed plant	1.83%	1.82%	1.85%
Gas and oil-fired
Property, Plant, and Equipment, and Depreciation
Composite depreciation rate for completed plant	3.31%	3.17%	3.38%
Transmission
Property, Plant, and Equipment, and Depreciation
Composite depreciation rate for completed plant	1.52%	1.52%	1.51%
Other
Property, Plant, and Equipment, and Depreciation
Composite depreciation rate for completed plant	4.98%	4.43%	3.64%

Summary of Significant Accoun_8

Summary of Significant Accounting Policies - Energy Prepayment Obligations and Discounts on Sales (Details) - USD ($) $ in Millions	Sep. 30, 2024	Sep. 30, 2023
Energy Prepayment Obligations and Discounts on Sales
Accounts Receivable, Allowance for Credit Loss, Current	$ 1	$ 1	[1]
[1]Allowance for uncollectible accounts was less than $1 million at both September 30, 2024 and 2023, and therefore is not represented in the table above.

Summary of Significant Accoun_9

Summary of Significant Accounting Policies - Leases (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Leases
Finance lease under PPA	$ 550	$ 390
Operating lease under PPA	121	135
Operating cash flows for operating leases	78	$ 77	$ 57
Finance Lease, Liability, Payment, Due	$ 1,133

Summary of Significant Accou_10

Summary of Significant Accounting Policies - Pre-commercial Plant Ops (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue capitalized during pre-commercial operations	$ 3	$ 3	$ 0
Fuel capitalized during pre-commercial ops	$ 3

Impact of New Accounting Stan_2

Impact of New Accounting Standards and Interpretations (Details) - USD ($) $ in Millions	Sep. 30, 2024	Sep. 30, 2023
Lessee, Lease, Description [Line Items]
Operating Lease, Right-of-Use Asset	$ 149	$ 177

Accounts Receivable, Net Acco_2

Accounts Receivable, Net Accounts Receivable, Net (Details) - USD ($) $ in Millions	Sep. 30, 2024	Sep. 30, 2023
Accounts, Notes, Loans and Financing Receivable [Line Items]
Power receivables	$ 1,683	$ 1,627
Other receivables	118	118
Accounts receivable, net	1,801	1,745
Allowance for uncollectible accounts - receivables	$ 1	$ 1	[1]
[1]Allowance for uncollectible accounts was less than $1 million at both September 30, 2024 and 2023, and therefore is not represented in the table above.

Inventories, Net Inventories,_2

Inventories, Net Inventories, Net (Details) - USD ($) $ in Millions	Sep. 30, 2024	Sep. 30, 2023
Inventories, Net
Materials and supplies inventory	$ 931	$ 849
Fuel inventory	286	313
Renewable energy certificates/emissions allowance inventory, net	11	15
Allowance for inventory obsolescence	(73)	(69)
Inventories, net	$ 1,155	$ 1,108

Deferred Costs, Capitalized, _5

Deferred Costs, Capitalized, Prepaid, and Other Assets (Details) - USD ($) $ in Millions	Sep. 30, 2024	Sep. 30, 2023
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Inventory, Work in Process, Gross	$ 41	$ 28
Prepaid long-term service agreements, current	7	25
Fair value	64	52
Other current assets	120	134
Prepaid Insurance	19	16
Other Assets, Miscellaneous, Current	13	19
Prepaid software maintenance	22	18
Other Intangible Assets, Net	$ 35	$ 15

Net Completed Plant Net Compl_2

Net Completed Plant Net Completed Plant (Details) - USD ($) $ in Millions	Sep. 30, 2024	Sep. 30, 2023
Completed Plant
Accumulated depreciation	$ 38,793	$ 35,871
Net completed plant	32,196	32,328
Property, Plant and Equipment, Gross	70,989	68,199
Coal-fired
Completed Plant
Completed plant cost	20,177	18,525
Accumulated depreciation	16,635	14,464
Net completed plant	3,542	4,061
Gas and oil-fired
Completed Plant
Completed plant cost	7,051	6,663
Accumulated depreciation	2,112	2,057
Net completed plant	4,939	4,606
Nuclear
Completed Plant
Completed plant cost	26,800	26,803
Accumulated depreciation	14,149	13,557
Net completed plant	12,651	13,246
Transmission
Completed Plant
Completed plant cost	9,964	9,375
Accumulated depreciation	3,450	3,359
Net completed plant	6,514	6,016
Hydroelectric
Completed Plant
Completed plant cost	4,307	4,109
Accumulated depreciation	1,288	1,241
Net completed plant	3,019	2,868
Other electrical plant
Completed Plant
Completed plant cost	1,763	1,798
Accumulated depreciation	737	780
Net completed plant	1,026	1,018
Multipurpose dams
Completed Plant
Completed plant cost	900	900
Accumulated depreciation	413	404
Net completed plant	487	496
Other stewardship
Completed Plant
Completed plant cost	27	26
Accumulated depreciation	9	9
Net completed plant	$ 18	$ 17

Other Long-Term Assets (Details

Other Long-Term Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023
Assets, Noncurrent [Abstract]
Financing Receivable, after Allowance for Credit Loss, Noncurrent	$ 84	$ 97
Financing Receivable, after Allowance for Credit Loss, Current	21	7
Prepaid long-term service agreements, noncurrent	62	64
Prepaid capital assets	29	28
Total other long-term assets	344	330
Other Long-Term Assets
Loans and Leases Receivable, Allowance	2	3
Other Assets, Miscellaneous, Current	13	19
Other Intangible Assets, Net	35	15
Prepaid long-term service agreements, noncurrent	62	64
Transfers Accounted for as Secured Borrowings, Assets, Carrying Amount, Long-term	44
Prepaid long-term service agreements, current	7	25
Transfers Accounted for as Secured Borrowings, Assets, Carrying Amount	56	55
Transfers Accounted for as Secured Borrowings, Assets, Carrying Amount Current	12	12
Other Noncurrent Assets [Member]
Assets, Noncurrent [Abstract]
Other Assets, Miscellaneous, Noncurrent	88	67
Other Long-Term Assets
Other Assets, Miscellaneous, Noncurrent	88	67
Transfers Accounted for as Secured Borrowings, Assets, Carrying Amount, Long-term		47
Other current assets
Other Long-Term Assets
Other Intangible Assets, Net	13	7
EnergyRight loan reserve
Other Long-Term Assets
Loans and Leases Receivable, Allowance	1	1
Economic development loan collective reserve
Other Long-Term Assets
Loans and Leases Receivable, Allowance	0	1
Economic development loan specific loan reserve
Other Long-Term Assets
Loans and Leases Receivable, Allowance	1	1
Other Noncurrent Assets [Member]
Assets, Noncurrent [Abstract]
Commodity contract derivative assets	2	12
Other Long-Term Assets
Commodity contract derivative assets	$ 2	$ 12
Energy Right
Other Long-Term Assets
Number of days in default	180 days
Minimum | Energy Right
Other Long-Term Assets
EnergyRight loan terms	5 years
Maximum | Energy Right
Other Long-Term Assets
EnergyRight loan terms	10 years

Regulatory Assets and Liabili_3

Regulatory Assets and Liabilities Regulatory Assets and Liabilities (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2024
Regulatory Assets and Liabilities
Non-current regulatory liabilities	$ 107	$ 107		$ 83
Current regulatory assets	178	178		191
Regulatory assets	5,566	5,566		9,408
Net unrealized gains (losses)	(52)	(52)		(64)
Regulatory Assets	5,744	5,744		9,599
Current regulatory liabilities	222	222		174
Regulatory asset amount expensed		31	$ 70
Regulatory Liabilities	329	329		257
Regulatory Asset
Regulatory Assets and Liabilities
Regulatory assets	152	152		154
Unrealized losses on interest rate derivatives
Regulatory Assets and Liabilities
Current regulatory assets	31	31		54
Regulatory assets	272	272		447
Non-nuclear decommissioning costs
Regulatory Assets and Liabilities
Regulatory assets	2,922	2,922		6,187
Increase (Decrease) in Deferred Charges	3,100
Pension Costs [Member]
Regulatory Assets and Liabilities
Regulatory assets	1,440	1,440		1,979
Unrealized gains/losses on commodity derivatives
Regulatory Assets and Liabilities
Current regulatory assets	136	136		102
Regulatory assets	52	52		64
Deferred Fuel Costs [Member]
Regulatory Assets and Liabilities
Current regulatory assets	11	11		35
Nuclear decommissioning costs
Regulatory Assets and Liabilities
Regulatory assets	728	728		362
Unrealized gains/losses on commodity derivatives
Regulatory Assets and Liabilities
Non-current regulatory liabilities	12	12		2
Current regulatory liabilities	21	21		5
Deferred other post-retirement benefits cost
Regulatory Assets and Liabilities
Non-current regulatory liabilities	95	95		81
Fuel cost adjustment tax equivalents
Regulatory Assets and Liabilities
Current regulatory liabilities	$ 201	$ 201		$ 169

Variable Interest Entities (Det

Variable Interest Entities (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022	Oct. 02, 2024	Sep. 30, 2013	Sep. 30, 2012
Liabilities
Current maturities of long-term debt of variable interest entities issued at par	$ 37	$ 35
Liabilities, Current	5,873	4,873
Other long-term liabilities	1,712	1,211
Long-term debt of variable interest entities, net	897	933
VIE Financing
Face Amount	$ 40				$ 360
Rate of Return SHLLC	7%
Accrued interest	$ 9	9
Minimum payments on membership interests subject to mandatory redemption, due in next twelve months	1
Minimum payments on membership interests subject to mandatory redemption, due in year two	1
Minimum payments on membership interests subject to mandatory redemption, due in year three	1
Minimum payments on membership interests subject to mandatory redemption, due in year four	1
Minimum payments on membership interests subject to mandatory redemption, due in year five	2
Minimum payments on membership interests subject to mandatory redemption, due thereafter	11
2018	1,022
2019	1,370
2020	1,020
2021	1,272
2022	220
Thereafter	14,175
Long-term debt of variable interest entities (including current maturities)	966	927
Amount of letters of credit outstanding	6
Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net	128	126
Variable Interest Entity, Primary Beneficiary [Member]
VIE Financing
Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net	5
Letter of Credit
VIE Financing
Amount of letters of credit outstanding	566	535
SCCG
VIE Financing
Debt and Lease Obligation					$ 400
Holdco
VIE Financing
Face Amount				$ 80		$ 100
JSCCG
VIE Financing
Face Amount						900
Variable Interest Entity, Primary Beneficiary [Member]
Liabilities
Liabilities, Current	47	45
Other long-term liabilities	16	17
VIE Financing
Debt and Lease Obligation				$ 800
Accounts Payable and Accrued Liabilities	1	1
Liabilities	960	995				$ 1,000
Interest Expense	46	$ 48	$ 50
2018	37
2019	39
2020	40
2021	42
2022	44
Thereafter	$ 737

Asset Retirement Obligations _3

Asset Retirement Obligations Asset Retirement Obligations (Details) - USD ($) $ in Millions		12 Months Ended
		Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Liabilities Settled [Line Items]
Increase in ARO liability		$ 3,300
Change in estimate	[1]	132	$ 369
Additional obligations		3,136
Balance	[1]	10,806	7,489	$ 7,162
Asset Retirement Obligation, Liabilities Settled	[1]	257	279
Accretion (recorded as regulatory asset)	[1]	306	237
Asset Retirement Obligation, Current		283	272
Amortization and Depreciation of Decontaminating and Decommissioning Assets		188	188	137
Total ARO change due to CCR			458
Change in estimate due to Gallatin CCR closure			60
Changes in closure liabilities			15
Increase in Asset Retirement Obligation, Revisions in Estimate			9
estimate revision of SLR		(164)
Nuclear
Liabilities Settled [Line Items]
Change in estimate		(160)	7
Additional obligations		0
Balance		3,814	3,808	3,643
Asset Retirement Obligation, Liabilities Settled		4	8
Accretion (recorded as regulatory asset)		170	166
Non-nuclear
Liabilities Settled [Line Items]
Change in estimate		292	362
Additional obligations		3,136
Balance		6,992	3,681	$ 3,519
Asset Retirement Obligation, Liabilities Settled		253	271
Accretion (recorded as regulatory asset)		$ 136	$ 71
[1] (1) Includes $283 million and $272 million at September 30, 2024 and 2023, respectively, in Current liabilities.

Other Long-Term Liabilities O_2

Other Long-Term Liabilities Other Long-Term Liabilities (Details) - USD ($) $ in Millions	Sep. 30, 2024	Sep. 30, 2023
Other Long-Term Liabilities
Interest rate swaps	$ 840	$ 662
Currency swap liabilities	116	141	[1]
Operating Lease, Liability, Noncurrent	88	93
Derivative, Fair Value, Net [Abstract]
EnergyRight financing obligation	(74)	(81)
Deferred Revenue, Noncurrent	48	45
Non-current regulatory liabilities	83	107
Total other long-term liabilities	1,712	1,211
Finance Lease, Liability	780
Deferred Compensation Liability, Current	(74)	(65)
Current portion of energy prepayment obligations	28	21
Fair value	64	52
Long-term debt of variable interest entities (including current maturities)	966	927
Long-term project cost accruals	140	10
Environmental Exit Costs, Costs Accrued to Date	212	0
Deferred Compensation Liability, Classified, Noncurrent	50	41
Other long-term liabilities
Other Long-Term Liabilities
Interest rate swaps	792	627
Currency swap liabilities	109	131
Derivative, Fair Value, Net [Abstract]
EnergyRight financing obligation	(52)	(55)
Customer Advances for Construction	55	56
Other	102	101
Accounts payable and accrued liabilities
Derivative, Fair Value, Net [Abstract]
EnergyRight financing obligation	(13)	(14)
Customer Advances for Construction	60	39
Long-term project cost accruals	124
Environmental Exit Costs, Costs Accrued to Date	$ 3	0
Accounts Payable [Member]
Derivative, Fair Value, Net [Abstract]
Long-term project cost accruals		$ 14
[1]See Note 15 — Risk Management Activities and Derivative Transactions — Offsetting of Derivative Assets and Liabilities .

Debt and Other Obligations De_2

Debt and Other Obligations Debt and Other Obligations - General (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2013
Debt Instrument
Debt ceiling	$ 30,000
Face Amount	$ 40	$ 360
PARRS 1998 Series D Bond
Debt Instrument
PARRS interest rate after rate reset	2.134%
Amount of bonds redeemed	$ 318
Amount of redeemable bond issues outstanding	$ 256
PARRS interest rate after rate reset	2.134%
PARRS 1999 Series A Bond
Debt Instrument
PARRS interest rate after rate reset	2.216%
Amount of bonds redeemed	$ 316
Amount of redeemable bond issues outstanding	$ 208
PARRS interest rate after rate reset	2.216%

Debt and Other Obligations De_3

Debt and Other Obligations Debt and Other Obligations - Secured Debt of VIEs (Details) - USD ($)	Oct. 02, 2024	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2013	Aug. 09, 2013	Sep. 30, 2012	Jan. 17, 2012
Variable Interest Entities
Face Amount		$ 40,000,000		$ 360,000,000
Financial Instruments Subject to Mandatory Redemption, Settlement Terms, Share Value, Amount		19,000,000	$ 19,000,000
Long-term debt of variable interest entities (including current maturities)		966,000,000	927,000,000
Reported Value Measurement
Variable Interest Entities
Financial Instruments Subject to Mandatory Redemption, Settlement Terms, Share Value, Amount		17,000,000	18,000,000
Long-term debt of variable interest entities (including current maturities)		934,000,000	$ 968,000,000
SCCG
Variable Interest Entities
Interest rate					3.846%
JSCCG
Variable Interest Entities
Face Amount						$ 900,000,000
Interest rate							4.626%
Holdco
Variable Interest Entities
Face Amount	$ 80,000,000					$ 100,000,000
Interest rate							7.10%
Holdco balloon payment upon maturity		$ 10,000,000

Debt and Other Obligations De_4

Debt and Other Obligations Debt and Other Obligations - Secured Notes of SPEs (Details) - USD ($) $ in Millions	Sep. 30, 2024	Sep. 30, 2013
Secured notes
Secured notes	$ 40	$ 360

Debt and Other Obligations De_5

Debt and Other Obligations Debt and Other Obligations - Short-Term Debt (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023
Short-Term Debt, Gross [Line Items]
Short-term Borrowings Gross	$ 1,168	$ 432
Weighted average interest rate - discount notes	4.76%	5.29%
Foreign Currency Transaction Gain (Loss), Unrealized	$ 62	$ 109

Debt and Other Obligations De_6

Debt and Other Obligations Debt and Other Obligations - Put and Call Options (Details) $ in Millions	12 Months Ended
	Sep. 30, 2024 USD ($)
PARRS 1998 Series D Bond
Debt Instrument
Amount of redeemable bond issues outstanding	$ 256
PARRS interest rate prior to rate reset	6.75%
PARRS interest rate after rate reset	2.134%
Amount of bonds redeemed	$ 318
PARRS 1999 Series A Bond
Debt Instrument
Amount of redeemable bond issues outstanding	$ 208
PARRS interest rate prior to rate reset	6.50%
PARRS interest rate after rate reset	2.216%
Amount of bonds redeemed	$ 316

Debt and Other Obligations De_7

Debt and Other Obligations Debt and Other Obligations - Debt Securities Activity (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2013
Debt Instrument
Face Amount	$ 40			$ 360
Discount on debt issues	(9)	$ (8)
Redemptions/Maturities of variable interest entities	35	39	$ 43
Redemptions/Maturities of power bonds	$ 1,022	$ 29	$ 1,028
Percent of par value	99.109%	99.187%
Total Current maturities of power bonds issued at par	$ 1,022	$ 1,022
Short-term debt, net of discounts	1,167	432
Current maturities of long-term debt of variable interest entities issued at par	37	35
Long-term power bonds, net	17,867	17,844
880591EF5 (12.15.20)
Debt Instrument
Total Current maturities of power bonds issued at par	$ 1	1
Interest rate	3.77%
Debt Instrument, Maturity Date	Dec. 15, 2024
880591EF5 (6.15.21)
Debt Instrument
Total Current maturities of power bonds issued at par	$ 21	21
Interest rate	3.77%
Debt Instrument, Maturity Date	Jun. 15, 2025
880591ER9
Debt Instrument
Total Current maturities of power bonds issued at par	$ 0	1,000
Interest rate	2.875%
Debt Instrument, Maturity Date	Sep. 15, 2024
880591EW8 [Member]
Debt Instrument
Total Current maturities of power bonds issued at par	$ 1,000	$ 0
Interest rate	0.75%
Debt Instrument, Maturity Date	May 15, 2025
Total
Debt Instrument
Debt Instrument, Redemption Period, End Date	1,057	68
Percent of par value	100%
Debt of variable interest entities
Debt Instrument
Redemptions/Maturities of variable interest entities	$ 35	$ 39
2009 Series B
Debt Instrument
Redemptions/Maturities of power bonds	22	29
2012 Series A
Debt Instrument
Redemptions/Maturities of power bonds	1,000	0
Total
Debt Instrument
Debt Securities Issues	$ 991	992
880591EY4
Debt Instrument
Interest rate	4.25%
Debt Instrument, Maturity Date	Sep. 15, 2052
Long-term power bonds, net	$ 500	500
880591EX6
Debt Instrument
Interest rate	1.50%
Debt Instrument, Maturity Date	Sep. 15, 2031
Long-term power bonds, net	$ 500	500
880591EZ1
Debt Instrument
Face Amount	$ 0	1,000
Interest rate	3.875%
Debt Instrument, Maturity Date	Mar. 15, 2028
Long-term power bonds, net	$ 1,000	1,000
880591FB3
Debt Instrument
Interest rate	4.375%
Debt Instrument, Maturity Date	Aug. 01, 2034
Long-term power bonds, net	$ 1,000	$ 0

Debt and Other Obligations De_8

Debt and Other Obligations Debt and Other Obligations - Debt Outstanding (Details) - USD ($) $ in Millions		12 Months Ended
		Sep. 30, 2024	Sep. 30, 2023
Short-term debt
Short-term debt, net of discounts		$ 1,167	$ 432
Current maturities of long-term debt of variable interest entities issued at par		37	35
Total Current maturities of power bonds issued at par		1,022	1,022
Total current debt outstanding, net		2,226	1,489
Long-term debt
Long-term power bonds, net		17,867	17,844
Long-term power bonds	[1]	17,995	17,970
Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net		(128)	(126)
Long-term debt of variable interest entities, net		897	933
Total long-term debt, net		$ 18,764	18,777
880591DX7
Short-term debt
Coupon rate		4.65%
Debt Instrument, Maturity Date		Jun. 15, 2035
Long-term debt
Long-term power bonds, net		$ 436	436
880591EF5
Short-term debt
Coupon rate		3.77%
Debt Instrument, Maturity Date		Jun. 15, 2034
Long-term debt
Long-term power bonds, net		$ 116	139
880591CJ9
Short-term debt
Coupon rate		6.75%
Debt Instrument, Maturity Date		Nov. 01, 2025
Long-term debt
Long-term power bonds, net		$ 1,350	1,350
880591EU2 [Member]
Short-term debt
Coupon rate		2.875%
Debt Instrument, Maturity Date		Feb. 01, 2027
Long-term debt
Long-term power bonds, net		$ 1,000	1,000
880591300
Short-term debt
Coupon rate		2.134%
Debt Instrument, Maturity Date		Jun. 01, 2028
Long-term debt
Long-term power bonds, net		$ 256	256
880591409
Short-term debt
Coupon rate		2.216%
Debt Instrument, Maturity Date		May 01, 2029
Long-term debt
Long-term power bonds, net		$ 208	208
880591DM1
Short-term debt
Coupon rate		7.125%
Debt Instrument, Maturity Date		May 01, 2030
Long-term debt
Long-term power bonds, net		$ 1,000	1,000
880591DV1
Short-term debt
Coupon rate		4.70%
Debt Instrument, Maturity Date		Jul. 15, 2033
Long-term debt
Long-term power bonds, net		$ 472	472
880591DP4
Short-term debt
Coupon rate		6.587%
Debt Instrument, Maturity Date		Jun. 07, 2032
Long-term debt
Long-term power bonds, net		$ 335	305
880591CK6
Short-term debt
Coupon rate		5.98%
Debt Instrument, Maturity Date		Apr. 01, 2036
Long-term debt
Long-term power bonds, net		$ 121	121
880591CS9
Short-term debt
Coupon rate		5.88%
Debt Instrument, Maturity Date		Apr. 01, 2036
Long-term debt
Long-term power bonds, net		$ 1,500	1,500
880591CP5
Short-term debt
Coupon rate		6.15%
Debt Instrument, Maturity Date		Jan. 15, 2038
Long-term debt
Long-term power bonds, net		$ 1,000	1,000
880591ED0
Short-term debt
Coupon rate		5.50%
Debt Instrument, Maturity Date		Jun. 15, 2038
Long-term debt
Long-term power bonds, net		$ 500	500
880591EH1
Short-term debt
Coupon rate		5.25%
Debt Instrument, Maturity Date		Sep. 15, 2039
Long-term debt
Long-term power bonds, net		$ 2,000	2,000
880591EP3
Short-term debt
Coupon rate		3.50%
Debt Instrument, Maturity Date		Dec. 15, 2042
Long-term debt
Long-term power bonds, net		$ 1,000	1,000
880591DU3
Short-term debt
Coupon rate		4.962%
Debt Instrument, Maturity Date		Jun. 07, 2043
Long-term debt
Long-term power bonds, net		$ 201	183
880591EB4
Short-term debt
Coupon rate		4.875%
Debt Instrument, Maturity Date		Jan. 15, 2048
Long-term debt
Long-term power bonds, net		$ 500	500
880591DZ2
Short-term debt
Coupon rate		5.375%
Debt Instrument, Maturity Date		Apr. 01, 2056
Long-term debt
Long-term power bonds, net		$ 1,000	1,000
880591EJ7
Short-term debt
Coupon rate		4.625%
Debt Instrument, Maturity Date		Sep. 15, 2060
Long-term debt
Long-term power bonds, net		$ 1,000	1,000
880591ES7
Short-term debt
Coupon rate		4.25%
Debt Instrument, Maturity Date		Sep. 15, 2065
Long-term debt
Long-term power bonds, net		$ 1,000	1,000
880591EW8 [Member]
Short-term debt
Coupon rate		0.75%
Debt Instrument, Maturity Date		May 15, 2025
Long-term debt
Long-term power bonds, net		$ 0	1,000
880591EX6
Short-term debt
Coupon rate		1.50%
Debt Instrument, Maturity Date		Sep. 15, 2031
Long-term debt
Long-term power bonds, net		$ 500	500
880591EY4
Short-term debt
Coupon rate		4.25%
Debt Instrument, Maturity Date		Sep. 15, 2052
Long-term debt
Long-term power bonds, net		$ 500	500
880591EZ1
Short-term debt
Coupon rate		3.875%
Debt Instrument, Maturity Date		Mar. 15, 2028
Long-term debt
Long-term power bonds, net		$ 1,000	1,000
880591FB3
Short-term debt
Coupon rate		4.375%
Debt Instrument, Maturity Date		Aug. 01, 2034
Long-term debt
Long-term power bonds, net		$ 1,000	$ 0
[1]nclude total net exchange gain from currency transactions of $62 million and $109 million at September 30, 2024 and 2023

Debt and Other Obligations De_9

Debt and Other Obligations Debt and Other Obligations - Maturities Due (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2030	Sep. 30, 2029	Sep. 30, 2028	Sep. 30, 2027	Sep. 30, 2026
Debt Instrument
2018	$ 1,022
2019	1,370
2020	1,020
2021	1,272
2022	220
Thereafter	14,175
Total	19,079
Short-Term Debt	1,167	$ 432
Net discount on sale of Bonds	87
Foreign Currency Transaction Gain (Loss), Unrealized	62	$ 109
Scenario, Forecast
Debt Instrument
Short-Term Debt			$ 0	$ 0	$ 0	$ 0	$ 0
Power bonds
Debt Instrument
Debt issuance costs	$ 41

Debt and Other Obligations D_10

Debt and Other Obligations Debt and Other Obligations - Credit Facility Agreements (Details)	Sep. 30, 2024 USD ($) Credit_facilities	Sep. 30, 2023 USD ($)
Credit Facility Agreements
Amount of letters of credit outstanding	$ 6,000,000
Letters of Credit Outstanding, Amount 3	134,000,000
Letter of Credit Outstanding, Amount 2	180,000,000
Long-term Line of Credit, Borrowings 3	0
Long-term Line of Credit, Borrowings 2	0
Borrowings under U.S. Treasury credit facility	0
Revolving Credit Facilities
Credit Facility Agreements
Current borrowing capacity	2,650,000,000
Credit facility agreements borrowings outstanding	$ 0
Number of revolving credit facilities | Credit_facilities	4
Revolving Credit Facility 4	$ 150,000,000
Revolving credit facility 3	1,000,000,000
Revolving credit facility 1	500,000,000
Revolving Credit Facility 2	1,000,000,000
Long-term Line of Credit, Borrowings 4	0
Long-term Line of Credit, Borrowings 1	0
Line of Credit Facility, Remaining Borrowing Capacity 4	112,000,000
Line of Credit Facility, Remaining Borrowing Capacity 2	820,000,000
Line of Credit Facility, Remaining Borrowing Capacity 3	866,000,000
Line of Credit Facility, Remaining Borrowing Capacity 1	286,000,000
Line of Credit Facility, Remaining Borrowing Capacity	2,084,000,000
Letter of Credit
Credit Facility Agreements
Amount of letters of credit outstanding	566,000,000	$ 535,000,000
Letters of Credit Outstanding, Amount 4	38,000,000
Letters of Credit Outstanding, Amount 1	214,000,000
Line of Credit
Credit Facility Agreements
Current borrowing capacity	$ 150,000,000

Risk Management Activities an_3

Risk Management Activities and Derivative Transactions Risk Management Activities and Derivative Transactions - Derivative Instruments That Receive Hedge Accounting Treatment (Details) - USD ($)	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Summary of Derivative Instruments That Receive Hedge Accounting Treatment
Interest rate swaps	$ 840,000,000	$ 662,000,000
Ineffective portion excluded from testing	0
Derivative Instruments, Gain (Loss) Reclassification from Accumulated OCI to Income, Estimated Net Amount to be Transferred	1,000,000
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, after Tax	48,000,000	42,000,000	$ (93,000,000)
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), before Reclassification, after Tax	$ 25,000,000	$ 99,000,000	$ (157,000,000)

Risk Management Activities an_4

Risk Management Activities and Derivative Transactions Risk Management Activities and Derivative Transactions - Derivative Instruments That Do Not Receive Hedge Accounting Treatment (Details)	12 Months Ended
	Sep. 30, 2024 USD ($)	Sep. 30, 2023 USD ($)
Derivative
Change in Unrealized gains (losses) on Interest Rate Derivatives	$ (182,000,000)	$ (240,000,000)
Fair value	64,000,000	52,000,000
Interest rate swaps	840,000,000	662,000,000
Interest Rate Swap
Derivative
Unrealized gains/losses on derivatives	(31,000,000)	$ (45,000,000)
Unrealized gains/losses on derivatives	$ 0
Commodity Contract Derivatives
Derivative
Number of contracts	45	54
Notional amount	321,000,000	318,000,000
Fair value	$ 2,000,000	$ 31,000,000
Commodity Contract under FHP
Derivative
Unrealized gains/losses on derivatives	$ (295,000,000)	$ (348,000,000)
Number of contracts	126	221
Notional amount	230	388
Fair value	$ (161,000,000)	$ (186,000,000)
Commodity Contract under FHP | Fuel Expense
Derivative
Unrealized gains/losses on derivatives	(245,000,000)	301,000,000
Commodity Contract under FHP | Purchased Power Expense
Derivative
Unrealized gains/losses on derivatives	(50,000,000)	47,000,000
Accounts payable and accrued liabilities | Commodity Contract Derivatives
Derivative
Fair value	(3,000,000)	(1,000,000)
Accounts payable and accrued liabilities | Commodity Contract under FHP
Derivative
Fair value	$ (99,000,000)	$ (135,000,000)

Risk Management Activities an_5

Risk Management Activities and Derivative Transactions Risk Management Activities and Derivative Transactions - Mark-to-Market Values of TVA Derivatives (Details) - USD ($) $ in Millions	Sep. 30, 2024	Sep. 30, 2023
Derivatives, Fair Value
Amount of letters of credit outstanding	$ 6
Fair value	64	$ 52
250 million Sterling currency swap
Derivatives, Fair Value
Fair value	(49)	(72)
250 million Sterling currency swap | Other long-term liabilities
Derivatives, Fair Value
Fair value	(45)	(66)
250 million Sterling currency swap | Accounts payable and accrued liabilities
Derivatives, Fair Value
Fair value	(4)	(6)
150 million Sterling currency swap
Derivatives, Fair Value
Fair value	(67)	(69)
150 million Sterling currency swap | Other long-term liabilities
Derivatives, Fair Value
Fair value	(64)	(65)
150 million Sterling currency swap | Accounts payable and accrued liabilities
Derivatives, Fair Value
Fair value	(3)	(4)
$1.0 billion notional interest rate swap
Derivatives, Fair Value
Fair value	(622)	(499)
$1.0 billion notional interest rate swap | Other long-term liabilities
Derivatives, Fair Value
Fair value	(586)	(473)
$1.0 billion notional interest rate swap | Other current assets
Derivatives, Fair Value
Fair value		1
$1.0 billion notional interest rate swap | Interest payable, current
Derivatives, Fair Value
Fair value	(26)	(27)
Commodity contract derivatives
Derivatives, Fair Value
Fair value	2	31
Commodity contract derivatives | Other Noncurrent Assets [Member]
Derivatives, Fair Value
Fair value	2	12
Commodity contract derivatives | Other long-term liabilities
Derivatives, Fair Value
Fair value	(2)	(1)
Commodity contract derivatives | Other current assets
Derivatives, Fair Value
Fair value	5	21
Commodity contract derivatives | Accounts payable and accrued liabilities
Derivatives, Fair Value
Fair value	(3)	(1)
$14 million notional
Derivatives, Fair Value
Fair value	(218)	(159)
$14 million notional | Other long-term liabilities
Derivatives, Fair Value
Fair value	(206)	(154)
$14 million notional | Interest payable, current
Derivatives, Fair Value
Fair value	(9)	(8)
Commodity Contract under FHP
Derivatives, Fair Value
Derivative Liability, Fair Value, Gross Liability	165	212
Fair value	(161)	(186)
Commodity Contract under FHP | Other long-term liabilities
Derivatives, Fair Value
Fair value	(62)	(51)
Commodity Contract under FHP | Accounts payable and accrued liabilities
Derivatives, Fair Value
Fair value	$ (99)	$ (135)

Risk Management Activities an_6

Risk Management Activities and Derivative Transactions Risk Management Activities and Derivative Transactions - Currency Swaps Outstanding (Details) £ in Millions	Sep. 30, 2024 GBP (£)
250 million Sterling currency swap
Derivative
Effective Date of Currency Swap Contract	2001
Associated TVA bond issues currency exposure	£ 250
Expiration Date of Swap	2032
Overall effective cost to TVA	6.587%
150 million Sterling currency swap
Derivative
Effective Date of Currency Swap Contract	2003
Associated TVA bond issues currency exposure	£ 150
Expiration Date of Swap	2043
Overall effective cost to TVA	4.962%

Risk Management Activities an_7

Risk Management Activities and Derivative Transactions Risk Management Activities and Derivative Transactions - Derivatives Under Financial Trading Program (Details) - USD ($) $ in Millions	Sep. 30, 2024	Sep. 30, 2023
Derivative
Unrealized gains (losses) deferred as regulatory liabilities (assets)	$ 64	$ 52

Risk Management Activities an_8

Risk Management Activities and Derivative Transactions Risk Management Activities and Derivative Transactions - Counterparty Credit Risk (Details) $ in Millions	12 Months Ended
	Sep. 30, 2024 USD ($) Customers	Sep. 30, 2023 USD ($)
Derivative
Receivables from power sales | $	$ 1,683	$ 1,627
Credit of Customers
Derivative
Number of customers that represent the percent of sales | Customers	2

Risk Management Activities an_9

Risk Management Activities and Derivative Transactions Risk Management Activities and Derivative Transactions - Offsetting of Derivative Assets (Details) - USD ($) $ in Millions	Sep. 30, 2024	Sep. 30, 2023
Offsetting Assets [Line Items]
Amount of letters of credit outstanding	$ 6
Letter of Credit
Offsetting Assets [Line Items]
Amount of letters of credit outstanding	566	$ 535
Commodity Contract under FHP
Offsetting Assets [Line Items]
Gross Amounts of Recognized Assets, subject to master netting or similar arrangements	$ 4	$ 26

Risk Management Activities a_10

Risk Management Activities and Derivative Transactions Risk Management Activities and Derivative Transactions - Offsetting of Derivative Liabilities (Details) - USD ($) $ in Millions	Sep. 30, 2024	Sep. 30, 2023
Offsetting Liabilities [Line Items]
Gross Amounts Offset in the Balance Sheet	$ 4	$ 26
Amount of letters of credit outstanding	6
Derivative Liability, Subject to Master Netting Arrangement, after Offset	1,122	991
Derivative Asset, Subject to Master Netting Arrangement, after Offset	7	37
Commodity contract derivatives	7	33
Currency Swap
Offsetting Liabilities [Line Items]
Derivative Liability, Subject to Master Netting Arrangement, after Offset	116	141
Commodity Contract under FHP
Offsetting Liabilities [Line Items]
Gross Amounts of Recognized Liabilities, subject to master netting or similar arrangements	165	212
Derivative Liability, Subject to Master Netting Arrangement, after Offset	161	186
Derivative Asset, Subject to Master Netting Arrangement, after Offset	0	0
Interest Rate Swap
Offsetting Liabilities [Line Items]
Derivative Liability, Subject to Master Netting Arrangement, after Offset	840	662
Derivative Asset, Subject to Master Netting Arrangement, after Offset	0	4
Commodity Contract Derivatives
Offsetting Liabilities [Line Items]
Derivative Liability, Subject to Master Netting Arrangement, after Offset	5	2
Derivative Asset, Subject to Master Netting Arrangement, after Offset	7	33
Letter of Credit
Offsetting Liabilities [Line Items]
Amount of letters of credit outstanding	$ 566	535
Interest rate swap collateral [Member]
Offsetting Liabilities [Line Items]
Amount of letters of credit outstanding		$ 509

Risk Management Activities a_11

Risk Management Activities and Derivative Transactions Risk Management Activities and Derivative Transactions - Other Derivative Instruments (Details) - USD ($) $ in Millions	Sep. 30, 2024	Sep. 30, 2023
Derivative
Forward Contract Derivative Asset, at Fair Value	$ 11	$ 11
Derivative Liability, Subject to Master Netting Arrangement, after Offset	1,122	991
Fair Value, Inputs, Level 2
Derivative
Forward Contract Derivative Asset, at Fair Value	$ 11	$ 11

Risk Management Activities a_12

Risk Management Activities and Derivative Transactions Risk Management Activities and Derivative Transactions - Collateral (Details) - USD ($) $ in Millions	Sep. 30, 2024	Sep. 30, 2023
Derivative
Amount of letters of credit outstanding	$ 6
Likely collateral obligation increase if downgraded	22
Derivative Liability, Subject to Master Netting Arrangement, after Offset	1,122	$ 991
Collateralized Securities [Member]
Derivative
Collateral obligations	552
Credit Risk
Derivative
Derivative Liability, Subject to Master Netting Arrangement, after Offset	1,100
Letter of Credit
Derivative
Amount of letters of credit outstanding	566	$ 535
Interest swap collateral
Derivative
Amount of letters of credit outstanding	$ 535

Risk Management Activities a_13

Risk Management Activities and Derivative Transactions Counterparty Credit Risk (Details)	12 Months Ended
	Sep. 30, 2024
Derivative
Two Largest Customer Percentage of Total Operating Revenue	17%
Moody's, A1 Rating
Derivative
Natural Gas Banking Counterparties Credit Rating	A1
Moody's, B1 Rating
Derivative
Natural Gas Banking Counterparties Credit Rating	B1
Moody's, A2 Rating
Derivative
Banking Counterparties Credit Rating	A2

Fair Value Measurements - Inves

Fair Value Measurements - Investments (Details) $ in Millions	12 Months Ended
	Sep. 30, 2024 USD ($) Units	Sep. 30, 2023 USD ($)
Fair Value, Measured on Recurring Basis, Gain (Loss) Included in Earnings [Line Items]
Long-term Investments	$ 4,968	$ 4,123
Period of time where the investor contributes capital to an investment in a private partnership - minimum | Units	3
Period of time where the investor contributes capital to an investment in a private partnership - maximum | Units	4
Minimum investment period	10 years
Fair value of gross plan assets	$ 8,959	8,605
Number of readily available quoted exchange prices for the investments	0
NDT
Fair Value, Measured on Recurring Basis, Gain (Loss) Included in Earnings [Line Items]
Long-term Investments	$ 3,300
ART
Fair Value, Measured on Recurring Basis, Gain (Loss) Included in Earnings [Line Items]
Long-term Investments	1,500
LTDCP
Fair Value, Measured on Recurring Basis, Gain (Loss) Included in Earnings [Line Items]
Unrealized gains (losses) on investments	2	1
SERP
Fair Value, Measured on Recurring Basis, Gain (Loss) Included in Earnings [Line Items]
Unrealized gains (losses) on investments	14	6
ART
Fair Value, Measured on Recurring Basis, Gain (Loss) Included in Earnings [Line Items]
Unrealized gains (losses) on investments	171	96
Debt and Equity Securities, Unrealized Gain (Loss)	36	13
NDT
Fair Value, Measured on Recurring Basis, Gain (Loss) Included in Earnings [Line Items]
Unrealized gains (losses) on investments	324	162
Debt and Equity Securities, Unrealized Gain (Loss)	93	27
Equity Funds [Member] | NDT
Fair Value, Measured on Recurring Basis, Gain (Loss) Included in Earnings [Line Items]
Commitments, Fair Value Disclosure	382
Real Estate Funds [Member] | NDT
Fair Value, Measured on Recurring Basis, Gain (Loss) Included in Earnings [Line Items]
Commitments, Fair Value Disclosure	120
Credit [Member] | NDT
Fair Value, Measured on Recurring Basis, Gain (Loss) Included in Earnings [Line Items]
Commitments, Fair Value Disclosure	87
Defensive growth assets | ART
Fair Value, Measured on Recurring Basis, Gain (Loss) Included in Earnings [Line Items]
Commitments, Fair Value Disclosure	152
Private real estate funds | ART
Fair Value, Measured on Recurring Basis, Gain (Loss) Included in Earnings [Line Items]
Commitments, Fair Value Disclosure	61
Private Credit [Member] | ART
Fair Value, Measured on Recurring Basis, Gain (Loss) Included in Earnings [Line Items]
Commitments, Fair Value Disclosure	46
RP
Fair Value, Measured on Recurring Basis, Gain (Loss) Included in Earnings [Line Items]
Debt and Equity Securities, Unrealized Gain (Loss)	$ 1	$ 1

Fair Value Measurements - Nonpe

Fair Value Measurements - Nonperformance Risk (Details) $ in Millions	Sep. 30, 2024 USD ($)
Nonperformance Risk
Derivative credit valuation adjustment, assets	$ 1
Derivative credit valuation adjustment, liabilities	$ 1

Fair Value Measurements - Fair

Fair Value Measurements - Fair Value Measurements (Details) - USD ($) $ in Millions	Sep. 30, 2024	Sep. 30, 2023
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value	$ 64	$ 52
Investments
Government debt securities	457	347
Corporate debt securities	378	300
Mortgage and asset-backed securities	43	36
Institutional mutual funds	342	288
Forward debt securities contracts - asset	11	11
Cash, Cash Equivalents, and Short-term Investments	278	270
Private equity funds measured at net asset value	738	583
Private real estate measured at net asset value	432	387
Private credit measured at net asset value	219	158
Commingled funds measured at net asset value	1,300	1,135
Total investments	4,968	4,123
Interest Rate Derivative Assets, at Fair Value	0	4
Commodity contract derivatives	7	33
Total	4,975	4,160
Liabilities
Currency swaps	116	141	[1]
Interest rate swaps	840	662
Commodity contract derivatives	5	2
Total	1,122	991
Equity Securities, FV-NI, Noncurrent	770	608
Derivative Liability, Subject to Master Netting Arrangement, after Offset	1,122	991
Derivative Asset, Subject to Master Netting Arrangement, after Offset	7	37
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Cash, Cash Equivalents, and Short-term Investments	278	270
Government debt securities reclassed		104
Commodity Contract under FHP
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value	(161)	(186)
Liabilities
Derivative Liability, Subject to Master Netting Arrangement, after Offset	161	186
Derivative Asset, Subject to Master Netting Arrangement, after Offset	0	0
Fair Value, Inputs, Level 1
Investments
Government debt securities	400	287
Corporate debt securities	0	0
Mortgage and asset-backed securities	0	0
Institutional mutual funds	342	288
Forward debt securities contracts - asset	0	0
Cash, Cash Equivalents, and Short-term Investments	95	104
Private equity funds measured at net asset value	0	0
Private real estate measured at net asset value	0	0
Private credit measured at net asset value	0	0
Commingled funds measured at net asset value	0	0
Total investments	1,607	1,287
Interest Rate Derivative Assets, at Fair Value	0	0
Commodity contract derivatives	0	0
Total	1,607	1,287
Liabilities
Currency swaps	0	0
Interest rate swaps	0	0
Commodity contract derivatives	0	0
Total	0	0
Equity Securities, FV-NI, Noncurrent	770	608
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Cash, Cash Equivalents, and Short-term Investments	95	104
Fair Value, Inputs, Level 1 | Commodity Contract under FHP
Liabilities
Derivative Liability, Subject to Master Netting Arrangement, after Offset	0	0
Fair Value, Inputs, Level 2
Investments
Government debt securities	57	60
Corporate debt securities	378	300
Mortgage and asset-backed securities	43	36
Institutional mutual funds	0	0
Forward debt securities contracts - asset	11	11
Cash, Cash Equivalents, and Short-term Investments	183	166
Private equity funds measured at net asset value	0	0
Private real estate measured at net asset value	0	0
Private credit measured at net asset value	0	0
Commingled funds measured at net asset value	0	0
Total investments	672	573
Interest Rate Derivative Assets, at Fair Value	0	4
Commodity contract derivatives	7	33
Total	679	610
Liabilities
Currency swaps	116	141
Interest rate swaps	840	662
Commodity contract derivatives	5	2
Total	1,122	991
Equity Securities, FV-NI, Noncurrent	0	0
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Cash, Cash Equivalents, and Short-term Investments	183	166
Fair Value, Inputs, Level 2 | Commodity Contract under FHP
Liabilities
Derivative Liability, Subject to Master Netting Arrangement, after Offset	161	186
Fair Value, Inputs, Level 3
Investments
Government debt securities	0	0
Corporate debt securities	0	0
Mortgage and asset-backed securities	0	0
Institutional mutual funds	0	0
Forward debt securities contracts - asset	0	0
Cash, Cash Equivalents, and Short-term Investments	0	0
Private equity funds measured at net asset value	0	0
Private real estate measured at net asset value	0	0
Private credit measured at net asset value	0	0
Commingled funds measured at net asset value	0	0
Total investments	0	0
Interest Rate Derivative Assets, at Fair Value	0	0
Commodity contract derivatives	0	0
Total	0	0
Liabilities
Currency swaps	0	0
Interest rate swaps	0	0
Commodity contract derivatives	0	0
Total	0	0
Equity Securities, FV-NI, Noncurrent	0	0
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Cash, Cash Equivalents, and Short-term Investments	0	0
Fair Value, Inputs, Level 3 | Commodity Contract under FHP
Liabilities
Derivative Liability, Subject to Master Netting Arrangement, after Offset	$ 0	$ 0
[1]See Note 15 — Risk Management Activities and Derivative Transactions — Offsetting of Derivative Assets and Liabilities .

Fair Value Measurements - Fai_2

Fair Value Measurements - Fair Value Measurements Using Significant Unobservable Inputs (Details) - USD ($) $ in Millions	Sep. 30, 2024	Sep. 30, 2023
Fair Value Measurements
Commodity contract derivatives, assets	$ 7	$ 33
Commodity contract derivatives, liabilities	5	2
Fair Value, Inputs, Level 3
Fair Value Measurements
Commodity contract derivatives, assets	0	0
Commodity contract derivatives, liabilities	$ 0	$ 0

Fair Value Measurements - Estim

Fair Value Measurements - Estimated Values of Financial Instruments (Details) - USD ($)	Sep. 30, 2024	Sep. 30, 2023
Estimated Values of Financial Instruments (Level 2 Valuation)
EnergyRight receivables (including current portion)	$ 56,000,000	$ 55,000,000
Financing Receivable, after Allowance for Credit Loss	99,000,000	96,000,000
EnergyRight® financing obligations (including current portion)	74,000,000	81,000,000
Unfunded Loan Commitments		1,000,000
Financial Instruments Subject to Mandatory Redemption, Settlement Terms, Share Value, Amount	19,000,000	19,000,000
Long-term outstanding power bonds (including current maturities), net	19,416,000,000	17,963,000,000
Long-term debt of variable interest entities (including current maturities)	966,000,000	927,000,000
Portion at Other than Fair Value Measurement [Member]
Estimated Values of Financial Instruments (Level 2 Valuation)
EnergyRight receivables (including current portion)	56,000,000	59,000,000
Reported Value Measurement
Estimated Values of Financial Instruments (Level 2 Valuation)
Financing Receivable, after Allowance for Credit Loss	105,000,000	104,000,000
EnergyRight® financing obligations (including current portion)	66,000,000	69,000,000
Unfunded Loan Commitments	0	0
Financial Instruments Subject to Mandatory Redemption, Settlement Terms, Share Value, Amount	17,000,000	18,000,000
Long-term outstanding power bonds (including current maturities), net	18,889,000,000	18,866,000,000
Long-term debt of variable interest entities (including current maturities)	$ 934,000,000	$ 968,000,000

Proprietary Capital (Details)

Proprietary Capital (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Appropriation Investment
Amount of appropriation investment that was repaid	$ 1,000
Net income (loss)	1,135	$ 500	$ 1,108
Return on power program appropriation investment	(7)	(6)	(4)
Net proprietary capital at September 30	$ 17,161	$ 16,056	$ 15,505	$ 14,465
Computed average interest rate payable	3.02%	1.99%	1.47%
Power Program Appropriation Investment
Appropriation Investment
Net income (loss)	$ 0	$ 0	$ 0
Return on power program appropriation investment	0	0	0
Power Program Retained Earnings
Appropriation Investment
Net income (loss)	1,142	508	1,115
Return on power program appropriation investment	(7)	(6)	4
Nonpower Programs Appropriation Investment, Net
Appropriation Investment
Net income (loss)	(7)	(8)	(7)
Return on power program appropriation investment	0	0	0
Affiliated Entity
Appropriation Investment
Return on power program appropriation investment	$ (7)	$ (6)	$ (4)

Proprietary Capital - Accumulat

Proprietary Capital - Accumulated Other Comprehensive Income (Loss) (Details) $ in Millions	12 Months Ended
	Sep. 30, 2024 USD ($)
Accumulated Other Comprehensive Income (Loss)
Reclassification to earnings from cash flow hedges in the next twelve months	$ (1)

Other Income (Expense), Net O_2

Other Income (Expense), Net Other Income (Expense), Net (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Other Income (Expense), Net
Interest income	$ 42	$ 34	$ 15
External services	17	15	16
Gain (Loss) on Investments	23	13	(17)
Miscellaneous	(11)	(1)	(7)
Other income (expense), net	$ 71	$ 61	$ 7

Benefit Plans Components of Ben

Benefit Plans Components of Benefit Plans (Details) - USD ($)	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Defined Benefit Plan Disclosure
Fixed and variable fund annual maximum contribution	$ 10,000
Defined contribution plan contribution amount	116,000,000	$ 105,000,000	$ 97,000,000
Nonqualified Excess 401(k) Plan	1,000,000	1,000,000
Accounts Payable and Accrued Liabilities, Current	$ 2,910,000,000	$ 2,618,000,000
Minimum
Defined Benefit Plan Disclosure
Threshold for Deferral of Actuarial Gain/Loss Under Corridor Approach	10%

Benefit Plans Obligations and F

Benefit Plans Obligations and Funded Status (Details) - USD ($) $ in Millions		12 Months Ended
		Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Pension Benefits
Change in benefit obligation
Benefit obligation		$ 10,099	$ 10,536
Defined Benefit Plan, Pension Plan with Projected Benefit Obligation in Excess of Plan Assets, Projected Benefit Obligation		11,002	10,099
Service cost		29	32	$ 53
Plan participants' contributions		3	4
Change in Plan Assets due to Collections		0	0
Collections	[1]	0	0
Actuarial loss (gain)		(1,059)	(284)
Net transfers from variable fund/401(k) plan		5	4
Expenses paid		(6)	(7)
Benefits paid		766	754
Defined Benefit Plan, Pension Plan with Projected Benefit Obligation in Excess of Plan Assets, Plan Assets		8,673	8,129
Change in plan assets
Fair value of net plan assets		8,129	8,094
Actual return on plan assets		1,004	482
Employer contributions		304	306
Defined Benefit Plan, Funded (Unfunded) Status of Plan [Abstract]
Funded status		$ (2,329)	$ (1,970)
Discount rate		4.95%	5.95%	5.60%
Amount of defined benefit plan actuarial gain (loss) from discount rate change		$ (981)	$ (334)
Amount of defined benefit plan actuarial gain (loss) from change in mortality assumption		(46)	(12)
Amount of defined benefit plan actuarial gain (loss) from change in demograhic and plan experience		37
Other Post-retirement Benefits
Change in benefit obligation
Benefit obligation		353	347
Postconfirmation, Other Postretirement Obligations			388
Service cost		11	10	$ 17
Plan participants' contributions		0	0
Change in Plan Assets due to Collections		12	13
Collections	[1]	12	13
Actuarial loss (gain)		4	44
Net transfers from variable fund/401(k) plan		0	0
Expenses paid		0	0
Benefits paid		34	38
Actuarial Gain (Loss) from Changes in Discount Rate		43
Actuarial Gain (Loss) from pre-Medicare Trend Rate Assumptions			27
Actuarial Gain (Loss) from Changes in Mortality Assumptions			17
Change in plan assets
Fair value of net plan assets		0	0
Actual return on plan assets		0	0
Employer contributions		22	25
Defined Benefit Plan, Funded (Unfunded) Status of Plan [Abstract]
Funded status		$ (353)	$ (347)
Discount rate		5%	6.05%	565%
Amount of defined benefit plan actuarial gain (loss) from change in demograhic and plan experience			$ 10
Amount of defined benefit plan actuarial gain (loss) from assumption change in elections			$ 61
[1]Collections include retiree contributions as well as provider discounts and rebates.

Benefit Plans Amounts Recognize

Benefit Plans Amounts Recognized on TVA's Consolidated Balance Sheets (Details) - USD ($) $ in Millions		Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Defined Benefit Plan Disclosure
Regulatory assets		$ (9,408)	$ (5,566)
Non-current regulatory liabilities		(83)	(107)
Accounts payable and accrued liabilities		(2,910)	(2,618)
Pension and post-retirement benefit obligations		(2,887)	(2,527)
Postemployment benefits liability, noncurrent		258	266
Pension Benefits
Defined Benefit Plan Disclosure
Regulatory assets		(1,979)	(1,440)
Accounts payable and accrued liabilities		(6)	(6)
Pension and post-retirement benefit obligations	[1]	(2,323)	(1,964)
Other Post-retirement Benefits
Defined Benefit Plan Disclosure
Regulatory assets		(81)	(95)
Non-current regulatory liabilities		(81)
Accounts payable and accrued liabilities		(20)	(21)
Pension and post-retirement benefit obligations	[1]	(333)	(326)
Pension and Other Postretirement Defined Benefit Plans, Liabilities, Noncurrent
Defined Benefit Plan Disclosure
Postemployment benefits liability, noncurrent		$ 230	$ 237	$ 299
[1]The table above excludes $230 million of post-employment benefit costs and $1 million of Restoration Plan costs at September 30, 2024, and $237 million of post-employment benefit costs at September 30, 2023 that are recorded in Post-retirement and post-employment benefit obligations on the Consolidated Balance Sheets.

Benefit Plans Postretirement Be

Benefit Plans Postretirement Benefit Costs Deferred as Regulatory Assets (Details) - USD ($) $ in Millions	Sep. 30, 2024	Sep. 30, 2023
Defined Benefit Plan Disclosure
Regulatory assets	$ (9,408)	$ (5,566)
Non-current regulatory liabilities	83	107
Pension Benefits
Defined Benefit Plan Disclosure
Unrecognized prior service cost (credit)	(247)	(336)
Unrecognized net loss	2,226	1,776
Regulatory assets	(1,979)	(1,440)
Other Post-retirement Benefits
Defined Benefit Plan Disclosure
Unrecognized prior service cost (credit)	(42)	(59)
Unrecognized net loss	(39)	(36)
Regulatory assets	(81)	$ (95)
Non-current regulatory liabilities	$ 81

Benefit Plans Projected Benefit

Benefit Plans Projected Benefit Obligations and Accumulated Benefit Obligations in Exess of Plan Assets (Details) - Pension Benefits - USD ($) $ in Millions	Sep. 30, 2024	Sep. 30, 2023
Defined Benefit Plan Disclosure
Accumulated benefit obligation	$ 10,971	$ 10,069
Defined Benefit Plan, Pension Plan with Projected Benefit Obligation in Excess of Plan Assets, Plan Assets	8,673	8,129
Fair value of net plan assets	$ 8,129	$ 8,094

Benefit Plans Components of Net

Benefit Plans Components of Net Periodic Benefit Cost (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Pension Benefits
Defined Benefit Plan Disclosure
Service cost	$ 29	$ 32	$ 53
DefinedBenefitPlanNetPeriodicBenefitCostCreditInterestCostStatementOfIncome	579	568	378
DefinedBenefitPlanNetPeriodicBenefitCostCreditExpectedReturnLossStatementOfIncome	(494)	(492)	(435)
DefinedBenefitPlanNetPeriodicBenefitCostCreditAmortizationOfPriorServiceCostCreditStatementOfIncome	(89)	(88)	(93)
DefinedBenefitPlanNetPeriodicBenefitCostCreditAmortizationOfGainLossStatementOfIncome	99	135	392
Net periodic benefit cost as acutarially determined	124	155	295
Amount expensed due to actions of regulator	0	(77)	(13)
Total net period benefit cost	124	232	308
Other Post-retirement Benefits
Defined Benefit Plan Disclosure
Service cost	11	10	17
DefinedBenefitPlanNetPeriodicBenefitCostCreditInterestCostStatementOfIncome	21	18	15
Expected return on plan assets	0	0	0
DefinedBenefitPlanNetPeriodicBenefitCostCreditAmortizationOfPriorServiceCostCreditStatementOfIncome	(17)	(17)	(17)
DefinedBenefitPlanNetPeriodicBenefitCostCreditAmortizationOfGainLossStatementOfIncome	(1)	2	(5)
Net periodic benefit cost as acutarially determined	14	9	20
Amount expensed due to actions of regulator	0	0	0
Total net period benefit cost	$ 14	$ 9	$ 20

Benefit Plans Actuarial Assumpt

Benefit Plans Actuarial Assumptions (Details) - USD ($)	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2025
Defined Benefit Plan Disclosure
Defined Benefit Plan, Cost of Living Adjustment Assumption	0.25%
Pension Benefits
Defined Benefit Plan Disclosure
Discount rate	5.95%	5.60%	2.90%
Discount rate	4.95%	5.95%	5.60%
Rate of compensation increase	4.01%	4.05%
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Weighted-Average Interest Crediting Rate	5.13%	5.13%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Weighted-Average Interest Crediting Rate	5.13%	5.14%	5.14%
Expected return on plan assets	6.50%	6.50%	5.75%
Defined Benefit Plan, Cost of Living Adjustment Assumption	2%	2%	2%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Rate of Compensation Increase		3.28%	3.32%
COLA percentage increase (decrease)	6%
Actual Return on Plan Assets	12.72%	6.13%	(6.64%)
Other Post-retirement Benefits
Defined Benefit Plan Disclosure
Discount rate	6.05%	5.65%	3.05%
Discount rate	5%	6.05%	565%
Defined Benefit Plan, Cost of Living Adjustment Assumption	2%	2%	2%
Minimum
Defined Benefit Plan Disclosure
Rate of compensation increase	3%
Maximum
Defined Benefit Plan Disclosure
Rate of compensation increase	5.50%
Scenario, Forecast | Pension Benefits
Defined Benefit Plan Disclosure
Defined Benefit Plan, Cost of Living Adjustment Assumption Next Fiscal Year				2.79%
Post-Medicare Eligible [Member] [Member] | Other Post-retirement Benefits
Defined Benefit Plan Disclosure
Current health care cost trend rate	0%	0%	0%
Ultimate health care cost trend rate	4%	4%	4%
Year health care cost ultimate trend rate is reached for Net Benefit Cost Assumption	2026	2026	2024
Defined Benefit Plan, Year Health Care Cost Trend Rate Reaches Ultimate Trend Rate	2026	2026
Pre-Medicare Eligible per Capita Claim Costs | Other Post-retirement Benefits
Defined Benefit Plan Disclosure
Current health care cost trend rate	7.50%	7%	6.25%
Ultimate health care cost trend rate	5%	5%	5%
Defined Benefit Plan, Year Health Care Cost Trend Rate Reaches Ultimate Trend Rate	2034	2034	2027
Initial health care cost trend rate	$ 0.0725	$ 0.0750
Defined Benefit Plan, Year ultimate trend rate is reached for net periodic benefit	2034	2031
Pre-Medicare Eligible per Capita Contributions | Other Post-retirement Benefits
Defined Benefit Plan Disclosure
Current health care cost trend rate	5%	5%	8.51%
Ultimate health care cost trend rate	5%	5%	5%
Defined Benefit Plan, Year ultimate trend rate is reached per capita contributions		2022
Defined Benefit Plan, Year Health Care Cost Trend Rate Reaches Ultimate Trend Rate	2034	2022	2027
Initial health care cost trend rate	$ 0.0725	$ 0.0500
Pre-Medicare Eligible per Capita Contributions | Pension Costs [Member]
Defined Benefit Plan Disclosure
Defined Benefit Plan, Year Health Care Cost Trend Rate Reaches Ultimate Trend Rate	2022

Benefit Plans Sensitivity to Ce

Benefit Plans Sensitivity to Certain Changes in Pension Assumptions (Details) - USD ($)	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Defined Benefit Plan Disclosure
Defined Benefit Plan, Cost of Living Adjustment Assumption	0.25%
Discount rate
Defined Benefit Plan Disclosure
Change in Assumption	(0.25%)
Impact on Pension Cost	$ 11,000,000
Impact on Projected Benefit Obligation	$ 273,000,000
Rate of return on plan assets
Defined Benefit Plan Disclosure
Change in Assumption	(0.25%)
Impact on Pension Cost	$ 19,000,000
Cost of Living Adjustments [Domain]
Defined Benefit Plan Disclosure
Change in Assumption	0.25%
Impact on Pension Cost	$ 22,000,000
Impact on Projected Benefit Obligation	$ 188,000,000
Other Post-retirement Benefits
Defined Benefit Plan Disclosure
Defined Benefit Plan, Cost of Living Adjustment Assumption	2%	2%	2%
Discount rate	5%	6.05%	565%
Actuarial assumption COLA	$ 0.0444	$ 0.06	$ 0.035
Pension Benefits
Defined Benefit Plan Disclosure
Defined Benefit Plan, Cost of Living Adjustment Assumption	2%	2%	2%
COLA percentage increase (decrease)	6%
Discount rate	4.95%	5.95%	5.60%

Benefit Plans Asset Holdings (D

Benefit Plans Asset Holdings (Details) - USD ($)	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Defined Benefit Plan Disclosure
Target Allocation	100%
Plan Asset Allocations	100%	100%
Growth Assets
Defined Benefit Plan Disclosure
Target Allocation	17%
Plan Asset Allocations	21%	22%
Defensive growth assets
Defined Benefit Plan Disclosure
Target Allocation	30%
Plan Asset Allocations	23%	33%
Defensive Assets
Defined Benefit Plan Disclosure
Target Allocation	33%
Plan Asset Allocations	34%	17%
Inflation-sensitive Assets
Defined Benefit Plan Disclosure
Target Allocation	20%
Plan Asset Allocations	22%	28%
Other Post-retirement Benefits
Defined Benefit Plan Disclosure
Actuarial assumption COLA	$ 0.0444	$ 0.06	$ 0.035

Benefit Plans Fair Value Measur

Benefit Plans Fair Value Measurements (Details) $ in Millions	12 Months Ended
	Sep. 30, 2024 USD ($) Years	Sep. 30, 2023 USD ($)	Oct. 01, 2019 USD ($)
Defined Benefit Plan Disclosure
Fair value of gross plan assets	$ 8,959	$ 8,605
Derivative liabilities	4	128
Net payables	47	167
Payables for collateral on loaned securities	$ 235	181
Voting percentage required to desolve partnership in private equity	80%
Fair Value, Inputs, Level 1
Defined Benefit Plan Disclosure
Fair value of gross plan assets	$ 1,396	1,748
Derivative liabilities	1	6
Fair Value, Inputs, Level 2
Defined Benefit Plan Disclosure
Fair value of gross plan assets	2,161	2,167
Derivative liabilities	3	122
Fair Value, Inputs, Level 3
Defined Benefit Plan Disclosure
Fair value of gross plan assets	65	60	$ 62
Derivative liabilities	0	0
Equity securities
Defined Benefit Plan Disclosure
Fair value of gross plan assets	670	732
Equity securities | Fair Value, Inputs, Level 1
Defined Benefit Plan Disclosure
Fair value of gross plan assets	668	731
Equity securities | Fair Value, Inputs, Level 2
Defined Benefit Plan Disclosure
Fair value of gross plan assets	0	0
Equity securities | Fair Value, Inputs, Level 3
Defined Benefit Plan Disclosure
Fair value of gross plan assets	2	1
Preferred securities
Defined Benefit Plan Disclosure
Fair value of gross plan assets	3	4
Preferred securities | Fair Value, Inputs, Level 1
Defined Benefit Plan Disclosure
Fair value of gross plan assets	0	0
Preferred securities | Fair Value, Inputs, Level 2
Defined Benefit Plan Disclosure
Fair value of gross plan assets	2	4
Preferred securities | Fair Value, Inputs, Level 3
Defined Benefit Plan Disclosure
Fair value of gross plan assets	1	0
Corporate debt securities
Defined Benefit Plan Disclosure
Fair value of gross plan assets	1,122	1,109
Corporate debt securities | Fair Value, Inputs, Level 1
Defined Benefit Plan Disclosure
Fair value of gross plan assets	0	0
Corporate debt securities | Fair Value, Inputs, Level 2
Defined Benefit Plan Disclosure
Fair value of gross plan assets	1,121	1,107
Corporate debt securities | Fair Value, Inputs, Level 3
Defined Benefit Plan Disclosure
Fair value of gross plan assets	1	2
Residential mortgage-backed securities
Defined Benefit Plan Disclosure
Fair value of gross plan assets	572
Residential mortgage-backed securities | Fair Value, Inputs, Level 1
Defined Benefit Plan Disclosure
Fair value of gross plan assets	0
Residential mortgage-backed securities | Fair Value, Inputs, Level 2
Defined Benefit Plan Disclosure
Fair value of gross plan assets	511	561
Residential mortgage-backed securities | Fair Value, Inputs, Level 3
Defined Benefit Plan Disclosure
Fair value of gross plan assets	61	55
Debt securities issued by U.S. Treasury and other U.S. government agencies
Defined Benefit Plan Disclosure
Fair value of gross plan assets	543	602
Debt securities issued by U.S. Treasury and other U.S. government agencies | Fair Value, Inputs, Level 1
Defined Benefit Plan Disclosure
Fair value of gross plan assets	543	602
Debt securities issued by U.S. Treasury and other U.S. government agencies | Fair Value, Inputs, Level 2
Defined Benefit Plan Disclosure
Fair value of gross plan assets	0	0
Debt securities issued by U.S. Treasury and other U.S. government agencies | Fair Value, Inputs, Level 3
Defined Benefit Plan Disclosure
Fair value of gross plan assets	0	0
Debt securities issued by state/local governments
Defined Benefit Plan Disclosure
Fair value of gross plan assets	23	21
Debt securities issued by state/local governments | Fair Value, Inputs, Level 1
Defined Benefit Plan Disclosure
Fair value of gross plan assets	0	0
Debt securities issued by state/local governments | Fair Value, Inputs, Level 2
Defined Benefit Plan Disclosure
Fair value of gross plan assets	23	21
Debt securities issued by state/local governments | Fair Value, Inputs, Level 3
Defined Benefit Plan Disclosure
Fair value of gross plan assets	0	0
Debt securities issued by foreign governments
Defined Benefit Plan Disclosure
Fair value of gross plan assets	19	12
Debt securities issued by foreign governments | Fair Value, Inputs, Level 1
Defined Benefit Plan Disclosure
Fair value of gross plan assets	0	0
Debt securities issued by foreign governments | Fair Value, Inputs, Level 2
Defined Benefit Plan Disclosure
Fair value of gross plan assets	19	10
Debt securities issued by foreign governments | Fair Value, Inputs, Level 3
Defined Benefit Plan Disclosure
Fair value of gross plan assets	0	2
Equity security commingled funds
Defined Benefit Plan Disclosure
Fair value of gross plan assets	245	360
Equity security commingled funds | Fair Value, Inputs, Level 1
Defined Benefit Plan Disclosure
Fair value of gross plan assets	0	0
Equity security commingled funds | Fair Value, Inputs, Level 2
Defined Benefit Plan Disclosure
Fair value of gross plan assets	0	0
Equity security commingled funds | Fair Value, Inputs, Level 3
Defined Benefit Plan Disclosure
Fair value of gross plan assets	0	0
Debt security commingled funds
Defined Benefit Plan Disclosure
Fair value of gross plan assets	1,236	544
Debt security commingled funds | Fair Value, Inputs, Level 1
Defined Benefit Plan Disclosure
Fair value of gross plan assets	0	0
Debt security commingled funds | Fair Value, Inputs, Level 2
Defined Benefit Plan Disclosure
Fair value of gross plan assets	0	0
Debt security commingled funds | Fair Value, Inputs, Level 3
Defined Benefit Plan Disclosure
Fair value of gross plan assets	0	0
Blended security commingled funds
Defined Benefit Plan Disclosure
Fair value of gross plan assets		101
Blended security commingled funds | Fair Value, Inputs, Level 1
Defined Benefit Plan Disclosure
Fair value of gross plan assets		0
Blended security commingled funds | Fair Value, Inputs, Level 2
Defined Benefit Plan Disclosure
Fair value of gross plan assets		0
Blended security commingled funds | Fair Value, Inputs, Level 3
Defined Benefit Plan Disclosure
Fair value of gross plan assets		0
Institutional mutual funds
Defined Benefit Plan Disclosure
Fair value of gross plan assets	180	363
Institutional mutual funds | Fair Value, Inputs, Level 1
Defined Benefit Plan Disclosure
Fair value of gross plan assets	180	363
Institutional mutual funds | Fair Value, Inputs, Level 2
Defined Benefit Plan Disclosure
Fair value of gross plan assets	0	0
Institutional mutual funds | Fair Value, Inputs, Level 3
Defined Benefit Plan Disclosure
Fair value of gross plan assets	0	0
Cash equivalents and other short-term investments
Defined Benefit Plan Disclosure
Fair value of gross plan assets	249	315
Cash equivalents and other short-term investments | Fair Value, Inputs, Level 1
Defined Benefit Plan Disclosure
Fair value of gross plan assets	5	51
Cash equivalents and other short-term investments | Fair Value, Inputs, Level 2
Defined Benefit Plan Disclosure
Fair value of gross plan assets	244	264
Cash equivalents and other short-term investments | Fair Value, Inputs, Level 3
Defined Benefit Plan Disclosure
Fair value of gross plan assets	0	0
Private Credit [Member]
Defined Benefit Plan Disclosure
Fair value of gross plan assets	1,126	694
Private Credit [Member] | Fair Value, Inputs, Level 1
Defined Benefit Plan Disclosure
Fair value of gross plan assets	0	0
Private Credit [Member] | Fair Value, Inputs, Level 2
Defined Benefit Plan Disclosure
Fair value of gross plan assets	0	0
Private Credit [Member] | Fair Value, Inputs, Level 3
Defined Benefit Plan Disclosure
Fair value of gross plan assets	0	0
Private equity funds measured at net asset value
Defined Benefit Plan Disclosure
Fair value of gross plan assets	1,580	1,769
Private equity funds measured at net asset value | Fair Value, Inputs, Level 1
Defined Benefit Plan Disclosure
Fair value of gross plan assets	0	0
Private equity funds measured at net asset value | Fair Value, Inputs, Level 2
Defined Benefit Plan Disclosure
Fair value of gross plan assets	0	0
Private equity funds measured at net asset value | Fair Value, Inputs, Level 3
Defined Benefit Plan Disclosure
Fair value of gross plan assets	0	0
Private real estate funds
Defined Benefit Plan Disclosure
Fair value of gross plan assets	1,150	1,162
Private real estate funds | Fair Value, Inputs, Level 1
Defined Benefit Plan Disclosure
Fair value of gross plan assets	0	0
Private real estate funds | Fair Value, Inputs, Level 2
Defined Benefit Plan Disclosure
Fair value of gross plan assets	0	0
Private real estate funds | Fair Value, Inputs, Level 3
Defined Benefit Plan Disclosure
Fair value of gross plan assets	0	0
Securities lending commingled funds
Defined Benefit Plan Disclosure
Fair value of gross plan assets	235	181
Securities lending commingled funds | Fair Value, Inputs, Level 1
Defined Benefit Plan Disclosure
Fair value of gross plan assets	0	0
Securities lending commingled funds | Fair Value, Inputs, Level 2
Defined Benefit Plan Disclosure
Fair value of gross plan assets	235	181
Securities lending commingled funds | Fair Value, Inputs, Level 3
Defined Benefit Plan Disclosure
Fair value of gross plan assets	0	0
Futures
Defined Benefit Plan Disclosure
Fair value of gross plan assets		1
Derivative liabilities	1	5
Futures | Fair Value, Inputs, Level 1
Defined Benefit Plan Disclosure
Fair value of gross plan assets		1
Derivative liabilities	1	5
Futures | Fair Value, Inputs, Level 2
Defined Benefit Plan Disclosure
Fair value of gross plan assets		0
Derivative liabilities	0	0
Futures | Fair Value, Inputs, Level 3
Defined Benefit Plan Disclosure
Fair value of gross plan assets		0
Derivative liabilities	0	0
Purchased options
Defined Benefit Plan Disclosure
Fair value of gross plan assets	6	17
Purchased options | Fair Value, Inputs, Level 1
Defined Benefit Plan Disclosure
Fair value of gross plan assets	0	0
Purchased options | Fair Value, Inputs, Level 2
Defined Benefit Plan Disclosure
Fair value of gross plan assets	6	17
Purchased options | Fair Value, Inputs, Level 3
Defined Benefit Plan Disclosure
Fair value of gross plan assets	0	0
Interest Rate Swap
Defined Benefit Plan Disclosure
Derivative liabilities	3	26
Interest Rate Swap | Fair Value, Inputs, Level 1
Defined Benefit Plan Disclosure
Derivative liabilities	0	0
Interest Rate Swap | Fair Value, Inputs, Level 2
Defined Benefit Plan Disclosure
Derivative liabilities	3	26
Interest Rate Swap | Fair Value, Inputs, Level 3
Defined Benefit Plan Disclosure
Derivative liabilities	$ 0	0
Foreign currency forward
Defined Benefit Plan Disclosure
Fair value of gross plan assets		2
Foreign currency forward | Fair Value, Inputs, Level 1
Defined Benefit Plan Disclosure
Fair value of gross plan assets		0
Foreign currency forward | Fair Value, Inputs, Level 2
Defined Benefit Plan Disclosure
Fair value of gross plan assets		2
Foreign currency forward | Fair Value, Inputs, Level 3
Defined Benefit Plan Disclosure
Fair value of gross plan assets		0
Credit default swaps
Defined Benefit Plan Disclosure
Derivative liabilities		1
Credit default swaps | Fair Value, Inputs, Level 1
Defined Benefit Plan Disclosure
Derivative liabilities		1
Credit default swaps | Fair Value, Inputs, Level 2
Defined Benefit Plan Disclosure
Derivative liabilities		0
Credit default swaps | Fair Value, Inputs, Level 3
Defined Benefit Plan Disclosure
Derivative liabilities		0
Securities Sold under Agreements to Repurchase [Member]
Defined Benefit Plan Disclosure
Derivative liabilities		96
Securities Sold under Agreements to Repurchase [Member] | Fair Value, Inputs, Level 1
Defined Benefit Plan Disclosure
Derivative liabilities		0
Securities Sold under Agreements to Repurchase [Member] | Fair Value, Inputs, Level 2
Defined Benefit Plan Disclosure
Derivative liabilities		96
Securities Sold under Agreements to Repurchase [Member] | Fair Value, Inputs, Level 3
Defined Benefit Plan Disclosure
Derivative liabilities		$ 0
Minimum
Defined Benefit Plan Disclosure
Number of years partnerships in private equity generally continue | Years	10
Number of one year extensions for partnerships in private equity | Years	2
Maximum
Defined Benefit Plan Disclosure
Number of years partnerships in private equity generally continue | Years	14
Number of one year extensions for partnerships in private equity | Years	3

Benefit Plans Fair Value Meas_2

Benefit Plans Fair Value Measurements Using Significant Unobservable Inputs (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Oct. 01, 2019
Defined Benefit Plan Disclosure
Net payables	$ 47	$ 167
Payables for collateral on loaned securities	235	181
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward]
Fair value of gross plan assets	8,959	8,605
Fair Value, Inputs, Level 3
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward]
Fair value of gross plan assets	65	60	$ 62
Net realized/unrealized gains	2	1
Purchases, sales, issuances, and settlements, net	10	2
Transfers in and/or out of Level 3	(7)	$ (5)
Fair value of net plan assets	$ 65

Benefit Plans Estimated Future

Benefit Plans Estimated Future Benefit Payments (Details) $ in Millions	Sep. 30, 2024 USD ($)
Pension Benefits
Defined Benefit Plan Disclosure
Defined Benefit Plan, Expected Future Benefit Payments, Next Twelve Months	$ 820
Defined Benefit Plan, Expected Future Benefit Payments, Year Two	821
Defined Benefit Plan, Expected Future Benefit Payments, Year Three	821
Defined Benefit Plan, Expected Future Benefit Payments, Year Four	819
Defined Benefit Plan, Expected Future Benefit Payments, Year Five	813
Defined Benefit Plan, Expected Future Benefit Payment, Five Fiscal Years Thereafter	3,917
Other Post-retirement Benefits
Defined Benefit Plan Disclosure
Defined Benefit Plan, Expected Future Benefit Payments, Next Twelve Months	20
Defined Benefit Plan, Expected Future Benefit Payments, Year Two	19
Defined Benefit Plan, Expected Future Benefit Payments, Year Three	19
Defined Benefit Plan, Expected Future Benefit Payments, Year Four	19
Defined Benefit Plan, Expected Future Benefit Payments, Year Five	19
Defined Benefit Plan, Expected Future Benefit Payment, Five Fiscal Years Thereafter	$ 106

Benefit Plans Contributions (De

Benefit Plans Contributions (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Defined Benefit Plan Disclosure
Defined contribution plan contribution amount		$ 116	$ 105	$ 97
Other postretirement benefit contributions		22	25
Contribution related to TVARS case		5	4
Supplemental Employee Retirement Plans, Defined Benefit
Defined Benefit Plan Disclosure
Defined Benefit Plan, Related to SERP		4	6
Other Post-retirement Benefits
Defined Benefit Plan Disclosure
Employer contributions		22	25
Pension Benefits
Defined Benefit Plan Disclosure
Employer contributions		304	$ 306
Other Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure
Employer contributions		300
Minimum | Other Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure
Employer contributions		$ 300
Scenario, Forecast | Other Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure
Employer contributions	$ 300

Benefit Plans Other Postemploym

Benefit Plans Other Postemployment Benefits (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2025
Other Post-Employment Benefits
Discount rate	3.81%	4.59%	3.83%
Period expense	$ 21	$ 3	$ 40
Postemployment benefits liability, noncurrent	258	266
Accounts Payable and Accrued Liabilities
Other Post-Employment Benefits
Postemployment Benefits Liability, Current	28	29
Accounts Payable and Accrued Liabilities | Scenario, Forecast
Other Post-Employment Benefits
Postemployment Benefits Liability, Current				$ 25
Pension and Other Postretirement Defined Benefit Plans, Liabilities, Noncurrent
Other Post-Employment Benefits
Postemployment benefits liability, noncurrent	$ 230	$ 237	$ 299

Commitments and Contingencies -

Commitments and Contingencies - Table (Details) $ in Millions		12 Months Ended
		Sep. 30, 2024 USD ($) megawatts	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)
Obligations
Megawatts provided under transmission obligations | megawatts		4,750
Accrual for Environmental Loss Contingencies, Gross		$ 15	$ 16
Estimated future decommissioning cost	[1]	$ 10,806	7,489	$ 7,162
Remaining terms of the transmission obligations, high end of range		5 years
Nuclear
Obligations
Estimated future decommissioning cost		$ 3,814	$ 3,808	$ 3,643
[1] (1) Includes $283 million and $272 million at September 30, 2024 and 2023, respectively, in Current liabilities.

Commitments and Contingencies_2

Commitments and Contingencies - Membership Interests of VIE Subject to Mandatory Redemption (Details) - USD ($) $ in Millions	Sep. 30, 2024	Sep. 30, 2023
Long-term Purchase Commitment [Line Items]
Financial Instruments Subject to Mandatory Redemption, Settlement Terms, Share Value, Amount	$ 19	$ 19
Minimum payments on membership interests subject to mandatory redemption, due in next twelve months	1
Minimum payments on membership interests subject to mandatory redemption, due in year two	1
Minimum payments on membership interests subject to mandatory redemption, due in year three	1
Minimum payments on membership interests subject to mandatory redemption, due in year four	1
Minimum payments on membership interests subject to mandatory redemption, due in year five	$ 2

Commitments and Contingencies_3

Commitments and Contingencies - Leases (Details) - USD ($) $ in Millions		Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Leases
Estimated future decommissioning cost	[1]	$ 10,806	$ 7,489	$ 7,162
[1] (1) Includes $283 million and $272 million at September 30, 2024 and 2023, respectively, in Current liabilities.

Commitments and Contingencies_4

Commitments and Contingencies - Purchase Obligations (Details) $ in Millions	12 Months Ended
	Sep. 30, 2024 USD ($) Megawatts Units megawatts	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)	Sep. 30, 2030 USD ($)	Sep. 30, 2029 USD ($)	Sep. 30, 2028 USD ($)	Sep. 30, 2027 USD ($)	Sep. 30, 2026 USD ($)	Sep. 30, 2025 USD ($)
Obligations
Megawatts provided under power purchase obligations | Megawatts	4,487
Remaining terms of the agreements, high end of range	11 years
Megawatts provided under transmission obligations | megawatts	4,750
Power purchased under agreement	$ 519	$ 355	$ 366
2019	$ 0
Scenario, Forecast
Obligations
Unrecorded Unconditional Purchase Obligation, Including Lease Not yet Commenced, Total				$ 413	$ 166	$ 165	$ 166	$ 166	$ 166
Purchase Agreements Required by Federal Law
Obligations
Megawatts provided under power purchase obligations | Units	279
Number of generation sources under PPAs | Units	1,197

Commitments and Contingencies_5

Commitments and Contingencies - Contingencies (Details) $ in Millions		12 Months Ended
		Sep. 30, 2024 USD ($) reactors Units Procedures Insurance_layers	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)
Contingencies
Nuclear liability insurance		$ 500
Assessment from licensees for each licensed reactor		$ 166
Number of licensed reactors in US | reactors		95
Nuclear accident assessment limitation per year per unit		$ 25
Number of licensed nuclear units | Units		7
Maximum assessment per nuclear incident		$ 1,200
Total amount of protection available		$ 16,300
Number of layers until the U.S. Congress is required to take action | Insurance_layers		2
Maximum amount of retrospective premiums		$ 114
Maximum idemnity if a covered accident tasks or keeps a nuclear unit offline		490
Maximum amount of retrospective premiums		44
Estimated future decommissioning cost	[1]	$ 10,806	$ 7,489	$ 7,162
Number of procedures for determining estimates for the costs of nuclear decommissioning | Procedures		2
Estimated liability for cleanup and similar environmental work on a non-discounted basis		$ 15	16
Amount of insurance available for loss at any one site (bottom range)		2,100
Amount of insurance available for loss at any one site (top range)		$ 2,800
Environmental Remediation
Contingencies
Accrual for Environmental Loss Contingencies, Significant Assumptions		215 million
Nuclear
Contingencies
Estimated future decommissioning cost		$ 3,814	3,808	3,643
Non-nuclear
Contingencies
Estimated future decommissioning cost		$ 6,992	$ 3,681	$ 3,519
[1] (1) Includes $283 million and $272 million at September 30, 2024 and 2023, respectively, in Current liabilities.

Commitments and Contingencies_6

Commitments and Contingencies - Legal Proceedings (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023
Legal Proceedings
Contribution related to TVARS case	$ 5	$ 4
Amount remaining to be spent under environmental agreements	7
General
Legal Proceedings
Legal loss contingency accrual	10
Environmental Agreements
Legal Proceedings
Amount to be invested in certain environmental projects	290
Amount invested in certain environmental projects	284
Other long-term liabilities | General
Legal Proceedings
Legal loss contingency accrual	9
Accounts payable and accrued liabilities | General
Legal Proceedings
Legal loss contingency accrual	$ 1

Commitments and Contingencies U

Commitments and Contingencies Unfunded loan commitments (Details) $ in Millions	Sep. 30, 2024 USD ($)
Other commitments - unfunded loan commitments [Abstract]
2019	$ 0
2020	$ 0

Related Parties Related Parti_2

Related Parties Related Parties (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Related Parties
Long-term Investments	$ 4,968	$ 4,123
Return on power program appropriation investment	(7)	(6)	$ (4)
Related Party Transactions
Related Parties
Revenue from sales of electricity	118	120	134
Other income	273	282	296
Operating expenses	241	234	228
Additions to property, plant, and equipment	12	8	11
Cash and cash equivalents	31	31	30
Receivables from Customers	81	87	78
Long-term Investments	495	391	358
Receivables, Long-term Contracts or Programs	35	38	43
Accounts payable and accrued liabilities	45	42	42
Long-term power bonds, net	3	1	1
Return on power program appropriation investment	$ (7)	$ (6)	$ (4)

Unaudited Quarterly Financial I

Unaudited Quarterly Financial Information Unaudited Quarterly Financial Information (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Quarterly Financial Information Disclosure [Abstract]
Operating expenses	$ 10,086	$ 10,360	$ 10,129
Operating income	2,228	1,694	2,411
Net income (loss)	$ 1,135	$ 500	$ 1,108

Revenue (Details)

Revenue (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Off-system sales	$ 8	$ 14	$ 19
Electric revenue	$ (12,123)	(11,888)	(12,352)
Pandemic Relief Credit		$ (225)	$ 228
Revenue from Contract with Customer [Abstract]
Percent of Pandemic Credit Offered	2.50%

Revenue Customer Type (Details)

Revenue Customer Type (Details) $ in Millions	12 Months Ended
	Sep. 30, 2024 USD ($) Units	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)
Electric revenue	$ 12,123	$ 11,888	$ 12,352
Bill credits for LTA	$ (215)	(199)	199
Percentage of total operating revenues	90.40%
Total number of LPCs | Units	153
Off-system sales	$ 8	14	19
Revenue capitalized during pre-commercial operations	$ (3)	(3)	0
Pandemic Relief Credit		$ (225)	228
Number of LPCs signed flexibility agreement | Units	102
Percent of sales of electricity to LPCs	92%	92%
Regulated Operating Revenue	$ 12,128	$ 11,899	12,371
Unregulated Operating Revenue	186	155	169
Regulated and Unregulated Operating Revenue	$ 12,314	$ 12,054	$ 12,540
MLGW's % of operating revenues	9%	9%	9%
NES's % of operating revenues	8%	8%	8%
ALABAMA
Regulated Operating Revenue	$ 1,768	$ 1,731	$ 1,778
GEORGIA
Regulated Operating Revenue	295	284	299
KENTUCKY
Regulated Operating Revenue	776	773	821
MISSISSIPPI
Regulated Operating Revenue	1,150	1,146	1,182
NORTH CAROLINA
Regulated Operating Revenue	89	89	87
TENNESSEE
Regulated Operating Revenue	7,998	7,819	8,137
VIRGINIA
Regulated Operating Revenue	$ 47	46	48
5-year contract arrangement [Member]
Number of LPCs signed LTA | Units	5
Percentage of total operating revenues	12.30%
Revenues	$ 1,517
20-year Termination Notice
Number of LPCs signed LTA | Units	148
Percentage of total operating revenues	78.10%
Revenues	$ 9,621
Federal agencies and other [Member]
Regulated Operating Revenue	125	135	154
Local Power Company [Member]
Electric revenue	11,138
Regulated Operating Revenue	11,138	10,903	11,291
Industries Directly Served [Member]
Regulated Operating Revenue	$ 868	$ 864	$ 926

Revenue Local Power Company Con

Revenue Local Power Company Contracts (Details) $ in Millions	12 Months Ended
	Sep. 30, 2024 USD ($) Units	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)
Electric revenue | $	$ 12,123	$ 11,888	$ 12,352
Total number of LPCs | Units	153
Percentage of total operating revenues	90.40%
Percent of wholesale Credit offered	3.10%
Local Power Company [Member]
Electric revenue | $	$ 11,138
5-year contract arrangement [Member]
Number of LPCs signed LTA | Units	5
Percentage of total operating revenues	12.30%

Revenue Economic Development In

Revenue Economic Development Incentives (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Revenue from Contract with Customer [Abstract]
Revenues	$ 318	$ 330	$ 328
Unpaid economic incentives	$ (187)	$ (188)

Subsequent Events (Details)

Subsequent Events (Details) - USD ($) $ in Millions	Oct. 02, 2024	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2013	Sep. 30, 2012
Debt Instrument, Redemption [Line Items]
Non-current regulatory liabilities		$ 83	$ 107
Regulatory assets		9,408	5,566
Face Amount		40		$ 360
Long-term debt of variable interest entities, net		897	933
Current maturities of long-term debt of variable interest entities issued at par		37	35
JACTG
Debt Instrument, Redemption [Line Items]
Face Amount	$ 720
Long-term debt of variable interest entities, net	791
Current maturities of long-term debt of variable interest entities issued at par	9
Variable Interest Entity, Primary Beneficiary [Member]
Debt Instrument, Redemption [Line Items]
Debt and Lease Obligation	800
Holdco
Debt Instrument, Redemption [Line Items]
Face Amount	$ 80				$ 100
Unrealized gains/losses on commodity derivatives
Debt Instrument, Redemption [Line Items]
Regulatory assets		64	52
Unrealized gains/losses on commodity derivatives
Debt Instrument, Redemption [Line Items]
Non-current regulatory liabilities		$ 2	$ 12

Plant Closures (Details)

Plant Closures (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended			57 Months Ended
	Sep. 30, 2024	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023
Property, Plant and Equipment [Abstract]
Accelerated depreciation			$ 177	$ 140	$ 659
Completed Plant
Accelerated depreciation			177	140	659
Depreciation		$ 1,800	1,900	$ 1,800
Accumulated depreciation	$ 38,793	38,793	$ 35,871		$ 35,871
Cumberland
Property, Plant and Equipment [Abstract]
Accelerated depreciation	16	112
Completed Plant
Accelerated depreciation	16	112
Kingston
Property, Plant and Equipment [Abstract]
Accelerated depreciation	9	18
Completed Plant
Accelerated depreciation	$ 9	$ 18
Property, Plant and Equipment [Member]
Completed Plant
Property, Plant and Equipment, Dispositions		15 million	14 million	22 million

Leases (Details)

Leases (Details) - USD ($)	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Lessee, Lease, Description [Line Items]
Operating Lease, Right-of-Use Asset	$ 149,000,000	$ 177,000,000
Finance Lease, Right-of-Use-Asset, after Accumulated Amortization	729,000,000	572,000,000
Total lease assets	$ 878,000,000	$ 749,000,000
Operating Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration]	Accounts Payable and Accrued Liabilities, Current	Accounts Payable and Accrued Liabilities, Current
Current Finance Lease Liability	$ 80,000,000	$ 56,000,000
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration]	Other long-term liabilities	Other long-term liabilities
Total lease liabilities	$ 931,000,000	$ 796,000,000
Operating Lease, Cost	77,000,000	69,000,000	$ 56,000,000
Variable Lease, Cost	258,000,000	134,000,000	78,000,000
Short-term Lease, Cost	10,000,000	18,000,000	26,000,000
Finance Lease, Right-of-Use Asset, Amortization	79,000,000	57,000,000	58,000,000
Finance Lease, Interest Expense	37,000,000	43,000,000	42,000,000
Total finance lease costs	116,000,000	100,000,000	100,000,000
Lease, Cost	461,000,000	321,000,000	$ 260,000,000
Operating lease under PPA	121,000,000	135,000,000
Finance Lease, Liability, Noncurrent	700,000,000	576,000,000
Leases
Finance lease under PPA	550,000,000	$ 390,000,000
New PPAs with battery storage	$ 991,000,000

Leases, SoCF (Details)

Leases, SoCF (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Lessee, Lease, Description [Line Items]
Operating cash flows for operating leases	$ 78	$ 77	$ 57
Operating cash flows for finance leases	37	43	42
Financing cash flows for finance leases	76	56	60
Lease assets obtained in exchange for lease obligations - finance	230	3	0
Lease assets obtained in exchange for lease obligations - operating	$ 115	$ 84	$ 43

Leases, Weighted Averages (Deta

Leases, Weighted Averages (Details)	Sep. 30, 2024	Sep. 30, 2023
Lessee, Lease, Description [Line Items]
Operating Lease, Weighted Average Remaining Lease Term	4 years	3 years
Finance Lease, Weighted Average Remaining Lease Term	9 years	10 years
Operating Lease, Weighted Average Discount Rate, Percent	4.30%	4.10%
Finance Lease, Weighted Average Discount Rate, Percent	17.60%	21.60%

Leases, Future Minimum Payments

Leases, Future Minimum Payments (Details) $ in Millions	Sep. 30, 2024 USD ($)
Lessee, Lease, Description [Line Items]
Operating Leases, Future Minimum Payments Due, Next Twelve Months	$ 68
Total	163
Operating Leases, Future Minimum Payments, Due in Two Years	34
Present value of future minimum lease payments, operating	(12)
Finance Lease, Liability, to be Paid, Year One	140
Finance Lease, Liability, to be Paid, Year Two	139
Finance Lease, Liability, to be Paid, Year Three	137
Finance Lease, Liability, to be Paid, Year Four	133
Finance Lease, Liability, to be Paid, Year Five	132
Finance Lease, Liability, to be Paid, after Year Five	452
Finance Lease, Liability, Payment, Due	1,133
Finance Lease, Liability, Payment Amounts Representing Interest	(353)
Finance Lease, Liability	780
Finance present value of net minimum lease payments	(151)
Operating Leases, Future Minimum Payments, Due in Three Years	31
Operating Leases, Future Minimum Payments, Due in Four Years	18
Operating Leases, Future Minimum Payments, Due in Five Years	4
Operating Leases, Future Minimum Payments, Due Thereafter	8
New PPAs with battery storage	$ 991

Research and Development (Detai

Research and Development (Details) - USD ($) $ in Millions	12 Months Ended		48 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2026
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research and Development Arrangement, Contract to Perform for Others, Costs Incurred, Gross	$ 41	$ 31
Amount of letters of credit outstanding	$ 6
Scenario, Forecast
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Other Research and Development Expense			$ 88