Tennessee Valley Authority PARRS D 2028 (TVC) 10-Q 31 Jul 23 2023 Q3 Quarterly report Financial data

DEI Document

DEI Document shares in Millions	9 Months Ended
	Jun. 30, 2023 shares
DEI [Abstract]
Entity Registrant Name	TENNESSEE VALLEY AUTHORITY
Current Fiscal Year End Date	--09-30
Entity Address, Country	US
Entity Filer Category	Non-accelerated Filer
Entity Emerging Growth Company	false
Document Type	10-Q
Document Period End Date	Jun. 30, 2023
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	Q3
Amendment Flag	false
Entity Common Stock, Shares Outstanding	0
Entity Current Reporting Status	Yes
Entity Shell Company	false
Document Quarterly Report	true
Local Phone Number	632-2101
City Area Code	(865)
Entity Tax Identification Number	62-0474417
Entity File Number	000-52313
Entity Address, Address Line One	400 W. Summit Hill Drive
Entity Address, City or Town	Knoxville
Entity Address, State or Province	TN
Entity Incorporation, State or Country Code	X1
Entity Address, Postal Zip Code	37902
Entity Interactive Data Current	Yes
Entity Central Index Key	0001376986
Entity Small Business	false
Document Transition Report	false
Document Information [Line Items]
Entity Incorporation, State or Country Code	X1

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS (UNAUDITED) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Operating revenues
Sales of Electricity	$ 2,664	$ 2,932	$ 8,551	$ 8,318
Other revenue	34	38	121	119
Revenues	2,698	2,970	8,672	8,437
Operating expenses
Fuel	530	539	1,845	1,563
Purchased power	350	465	1,234	1,208
Operating and maintenance	896	722	2,546	2,269
Depreciation and amortization	548	513	1,631	1,535
Tax equivalents	137	141	435	412
Total operating expenses	2,461	2,380	7,691	6,987
Operating income	237	590	981	1,450
Other income (expense), net	20	(6)	57	11
Defined Benefit Plan, Other Cost (Credit)	51	64	153	194
Interest expense
Interest expense	264	264	794	791
Net income (loss)	$ (58)	$ 256	$ 91	$ 476

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (UNAUDITED) - USD ($)	3 Months Ended			9 Months Ended
	Jun. 30, 2023	Jun. 30, 2022		Jun. 30, 2023		Jun. 30, 2022
Net income (loss)	$ (58,000,000)	$ 256,000,000		$ 91,000,000		$ 476,000,000
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), before Reclassification, after Tax	5,000,000	(40,000,000)		79,000,000		(50,000,000)
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, after Tax	22,000,000	(34,000,000)	[1]	65,000,000	[1]	(50,000,000)
Other comprehensive income (loss)
Total other comprehensive income (loss)	(17,000,000)	(6,000,000)		14,000,000		0
Total comprehensive income (loss)	$ (75,000,000)	$ 250,000,000		$ 105,000,000		$ 476,000,000
[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 $4 million of gains from Accumulated other comprehensive income (loss) ("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.

CONSOLIDATED BALANCE SHEETS (UN

CONSOLIDATED BALANCE SHEETS (UNAUDITED) - USD ($) $ in Millions	Jun. 30, 2023	Sep. 30, 2022
Current assets
Cash and cash equivalents	$ 500	$ 500
Accounts receivable, net	1,603	2,007
Inventories, net	1,185	1,072
Regulatory assets	236	138
Other current assets	161	257
Total current assets	3,685	3,974
Property, plant, and equipment
Completed plant	67,229	66,442
Less accumulated depreciation	(35,223)	(34,239)
Net completed plant	32,006	32,203
Construction in progress	3,161	2,535
Nuclear fuel	1,410	1,492
Finance lease, asset	584	630
Total property, plant, and equipment, net	37,161	36,860
Investment funds	4,202	3,671
Regulatory and other long-term assets
Regulatory assets	5,666	6,134
Operating Lease, Right-of-Use Asset	165	155
Other long-term assets	334	394
Total regulatory and other long-term assets	6,165	6,683
Total assets	51,213	51,188
Current liabilities
Accounts payable and accrued liabilities	2,431	2,466
Accrued interest	252	273
Asset Retirement Obligation, Current	262	275
Regulatory liabilities	224	391
Short-term debt, net	722	1,172
Current maturities of power bonds	22	29
Current maturities of long-term debt of variable interest entities	35	39
Total current liabilities	3,948	4,645
Other liabilities
Post-retirement and post-employment benefit obligations	2,909	3,072
Asset retirement obligations	6,860	6,887
Finance Lease, Liability, Noncurrent	594	628
Other long-term liabilities	1,425	1,485
Regulatory liabilities	59	172
Total other liabilities	11,847	12,244
Long-term debt, net
Long-term power bonds, net	18,861	17,826
Long-term debt of variable interest entities, net	951	968
Total long-term debt, net	19,812	18,794
Total liabilities	35,607	35,683
Proprietary capital
Power program appropriation investment	258	258
Power program retained earnings	14,893	14,800
Total power program proprietary capital	15,151	15,058
Nonpower programs appropriation investment, net	527	533
Accumulated other comprehensive income (loss)	(72)	(86)
Total proprietary capital	15,606	15,505
Total liabilities and proprietary capital	$ 51,213	$ 51,188

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED) - USD ($) $ in Millions	9 Months Ended
	Jun. 30, 2023		Jun. 30, 2022
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	$ 520		$ 521
Cash flows from operating activities
Net income (loss)	91		476
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)	1,647		1,551
Amortization of nuclear fuel cost	268		252
Non-cash retirement benefit expense	186		246
Other regulatory amortization and deferrals	26		(203)
Changes in current assets and liabilities
Accounts receivable, net	401		(184)
Inventories and other current assets, net	(190)		131
Accounts payable and accrued liabilities	(120)		298
Accrued interest	(24)		(34)
Pension contributions	(231)		(233)
Other, net	(278)		204
Net cash provided by operating activities	1,776		1,834
Cash flows from investing activities
Construction expenditures	(1,825)		(1,772)
Nuclear fuel expenditures	(267)		(235)
Acquisition of leasehold interests in combustion turbine assets	(155)		0
Loans and other receivables
Advances	(7)		(9)
Repayments	6		12
Other, net	15		26
Net cash used in investing activities	(2,233)		(1,978)
Long-term debt
Redemptions and repurchases of power bonds	(29)	[1]	(28)
Repayments of Other Long-term Debt	22		21
Short-term debt issues (redemptions), net	(450)		254
Finance Lease, Principal Payments	36		63
Other, net	6		5
Net cash provided by (used in) financing activities	457		147
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect	0		3
Proceeds from Issuance of Debt	992		0
Payments of Financing Costs	(4)		$ 0
Cash and cash equivalents at end of period	$ 500
[1] (1) The 2023 Series A Bonds were issued at 99.187 percent of par. (2) All redemptions were at 100 percent of par.

CONSOLIDATED STATEMENTS OF CHAN

CONSOLIDATED STATEMENTS OF CHANGES IN PROPRIETARY CAPITAL (UNAUDITED) - USD ($)	3 Months Ended		9 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022	Mar. 31, 2023	Sep. 30, 2022	Mar. 31, 2022	Sep. 30, 2021
Power Program Appropriation Investment	$ 258,000,000		$ 258,000,000			$ 258,000,000
Power Program Retained Earnings	14,893,000,000		14,893,000,000			14,800,000,000
Nonpower Programs Appropriation Investment, Net	527,000,000		527,000,000			533,000,000
Accumulated Other Comprehensive Income (Loss) from Net Gains (Losses) on Cash Flow Hedges	(72,000,000)		(72,000,000)			(86,000,000)
Total Proprietary Capital	15,606,000,000	$ 14,938,000,000	15,606,000,000	$ 14,938,000,000	$ 15,682,000,000	15,505,000,000	$ 14,689,000,000	$ 14,465,000,000
Net income (loss)	(58,000,000)	256,000,000	91,000,000	476,000,000
Total other comprehensive income (loss)	(17,000,000)	(6,000,000)	14,000,000	0
Return on power program appropriation investment	(1,000,000)	(1,000,000)	(4,000,000)	(3,000,000)
Power Program Appropriation Investment
Power Program Appropriation Investment	258,000,000	258,000,000	258,000,000	258,000,000	258,000,000	258,000,000	258,000,000	258,000,000
Net income (loss)		0	0	0
Total other comprehensive income (loss)		0	0
Return on power program appropriation investment		0	0	0
Power Program Retained Earnings
Power Program Retained Earnings	14,893,000,000	14,167,000,000	14,893,000,000	14,167,000,000	14,950,000,000	14,800,000,000	13,910,000,000	13,689,000,000
Net income (loss)	(56,000,000)	258,000,000	97,000,000	481,000,000
Total other comprehensive income (loss)		0	0
Return on power program appropriation investment	(1,000,000)	(1,000,000)	(4,000,000)	(3,000,000)
Nonpower Programs Appropriation Investment, Net
Nonpower Programs Appropriation Investment, Net	527,000,000	535,000,000	527,000,000	535,000,000	529,000,000	533,000,000	537,000,000	540,000,000
Net income (loss)	(2,000,000)	(2,000,000)	(6,000,000)	(5,000,000)
Total other comprehensive income (loss)		0	0
Return on power program appropriation investment		0	0	0
Accumulated Other Comprehensive Income (Loss) from Net Gains (Losses) on Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss) from Net Gains (Losses) on Cash Flow Hedges	(72,000,000)	(22,000,000)	(72,000,000)	(22,000,000)	$ (55,000,000)	$ (86,000,000)	$ (16,000,000)	$ (22,000,000)
Net income (loss)		0	0	0
Total other comprehensive income (loss)	$ (17,000,000)	(6,000,000)	14,000,000
Return on power program appropriation investment		$ 0	$ 0	$ 0

Supplemental Cash Flow Informat

Supplemental Cash Flow Information Statement - USD ($) $ in Millions	9 Months Ended
	Jun. 30, 2023	Jun. 30, 2022
Other Significant Noncash Transactions [Line Items]
Capital Expenditures Incurred but Not yet Paid	$ 464	$ 470

Statement of Cash Flows, Supple

Statement of Cash Flows, Supplemental Disclosures	9 Months Ended
	Jun. 30, 2023
Supplemental Cash Flow Elements [Abstract]
Cash Flow, Supplemental Disclosures	Supplemental Cash Flow Information Construction in progress and asset retirement obligation project accruals and nuclear fuel expenditures included in Accounts payable and accrued liabilities at June 30, 2023 and 2022, were $464 million and $470 million, respectively, and are excluded from the Consolidated Statements of Cash Flows for the nine months ended June 30, 2023 and 2022, as non-cash investing activities. 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.

Summary of Significant Accounti

Summary of Significant Accounting Policies (Text Block)	9 Months Ended
	Jun. 30, 2023
Accounting Policies [Abstract]
Nature of Operations and Summary of Significant Accounting Policies	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, 16 U.S.C. §§ 831-831ee ("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 (2023, 2022, 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. Basis of Presentation TVA prepares its consolidated interim financial statements in conformity with GAAP for consolidated interim financial information. Accordingly, TVA's consolidated interim financial statements do not include all of the information and notes required by GAAP for annual financial statements. As such, they should be read in conjunction with the audited financial statements for the year ended September 30, 2022, and the notes thereto, which are contained in TVA's Annual Report on Form 10-K for the year ended September 30, 2022 (the "Annual Report"). In the opinion of management, all adjustments (consisting of items of a normal recurring nature) considered necessary for fair presentation are included on the consolidated interim financial statements. The accompanying consolidated interim 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 9 — 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. 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 (in millions) At June 30, 2023 At September 30, 2022 Cash and cash equivalents $ 500 $ 500 Restricted cash and cash equivalents included in Other long-term assets 20 20 Total cash, cash equivalents, and restricted cash $ 520 $ 520 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 June 30, 2023, and September 30, 2022, for trade accounts receivable. Additionally, loans receivable of $135 million and $105 million at June 30, 2023, and September 30, 2022, 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 $3 million at both June 30, 2023 and September 30, 2022. 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. 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 (expense), net. 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. Colbert combustion turbine units 9-10 commenced pre-commercial plant operations in June 2023 and became operational on July 25, 2023. Estimated revenue of less than $1 million related to this project was capitalized to offset project costs for the three and nine months ended June 30, 2023. TVA also capitalized related fuel costs for this project of $1 million for the three and nine months ended June 30, 2023. 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 at least every five years, with the latest study implemented during the first quarter of 2022. Depreciation expense was $482 million and $459 million for the three months ended June 30, 2023 and 2022, respectively. Depreciation expense was $1.4 billion for both the nine months ended June 30, 2023 and 2022. See Note 6 — Plant Closures for a discussion of the impact of plant closures.

Impact of New Accounting Standa

Impact of New Accounting Standards and Interpretations (Text Block)	9 Months Ended
	Jun. 30, 2023
Accounting Changes and Error Corrections [Abstract]
Accounting Standards Update and Change in Accounting Principle	Impact of New Accounting Standards and Interpretations The following accounting standards have been issued but, at June 30, 2023, were not effective and had not been adopted by TVA: 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 This new standard is effective for TVA’s interim and annual reporting periods beginning October 1, 2023. While early adoption is permitted, TVA does not currently plan to adopt this standard early. Effect on the Financial Statements or Other Significant Matters TVA does not expect the adoption of this standard to have a material impact on its 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 This new standard is effective for TVA’s interim and annual reporting periods beginning October 1, 2023. While early adoption is permitted, TVA does not currently plan to adopt this standard early. Effect on the Financial Statements or Other Significant Matters TVA does not expect the adoption of this standard to have a material impact on its financial condition, results of operations, or cash flows.

Accounts Receivable, Net (Text

Accounts Receivable, Net (Text Block)	9 Months Ended
	Jun. 30, 2023
Accounts Receivable, after Allowance for Credit Loss [Abstract]
Accounts Receivable, Net	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 (in millions) At June 30, 2023 At September 30, 2022 Power receivables $ 1,514 $ 1,899 Other receivables 89 108 Accounts receivable, net (1) $ 1,603 $ 2,007 Note

Inventories, Net (Text Block)

Inventories, Net (Text Block)	9 Months Ended
	Jun. 30, 2023
Inventory, Net [Abstract]
Inventories, Net	Inventories, Net The table below summarizes the types and amounts of TVA's inventories: Inventories, Net (in millions) At June 30, 2023 At September 30, 2022 Materials and supplies inventory $ 842 $ 808 Fuel inventory 401 303 Renewable energy certificates/emissions allowance inventory, net 17 18 Allowance for inventory obsolescence (75) (57) Inventories, net $ 1,185 $ 1,072

Deferred Costs, Capitalized, Pr

Deferred Costs, Capitalized, Prepaid, and Other Assets (Text Block)	9 Months Ended
	Jun. 30, 2023
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Other Current Assets	Other Current Assets Other current assets consisted of the following: Other Current Assets (in millions) At June 30, 2023 At September 30, 2022 (1) Commodity contract derivative assets $ 21 $ 172 Prepaid software maintenance 28 14 Prepaid insurance 26 16 Current portion of prepaid long-term service agreements 22 12 Other 64 43 Other current assets $ 161 $ 257 Note (1) At September 30, 2022, $14 million, $16 million, and $12 million previously classified as Other (a component of Other current assets) have been reclassified to Prepaid software maintenance (a component of Other current assets), Prepaid insurance (a component of Other current assets), and Current portion of prepaid long-term service agreements (a component of Other current assets), respectively, to conform with 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 13 — Risk Management Activities and Derivative Transactions — Derivatives Not Receiving Hedge Accounting Treatment — Commodity Contract Derivatives and — Commodity Derivatives under the FHP for a

Plant Closures (Text Block)

Plant Closures (Text Block)	9 Months Ended
	Jun. 30, 2023
Property, Plant and Equipment Impairment or Disposal [Abstract]
Plant Closures Disclosure	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. 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. Due to these evaluations, certain planning assumptions were updated, and their financial impacts are discussed below. In January 2023, TVA issued its Record of Decision to retire the two coal-fired units at Cumberland Fossil Plant ("Cumberland") by the end of CY 2026 and CY 2028. 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 $592 million of accelerated depreciation since the second quarter of 2019. Of this amount, $37 million and $35 million were recognized for Bull Run during the three months ended June 30, 2023 and 2022, respectively, and $110 million and $105 million were recognized during the nine months ended June 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. TVA has recognized a cumulative $32 million of additional depreciation since January 2023.

Other Long-Term Assets (Text Bl

Other Long-Term Assets (Text Block)	9 Months Ended
	Jun. 30, 2023
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Other Long-Term Assets	Other Long-Term Assets The table below summarizes the types and amounts of TVA's other long-term assets: Other Long-Term Assets (in millions) At June 30, 2023 At September 30, 2022 Loans and other long-term receivables, net $ 131 $ 99 EnergyRight ® receivables, net 47 49 Prepaid long-term service agreements 57 74 Commodity contract derivative assets 1 102 Other 98 70 Total other long-term assets $ 334 $ 394 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 June 30, 2023 and September 30, 2022, the carrying amount of the loans receivable, net of discount, reported in Accounts receivable, net was $4 million and $6 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 June 30, 2023, and September 30, 2022, the carrying amount of the loans receivable, net of discount, reported in Accounts receivable, net was $12 million and $13 million, respectively. See Note 10 — Other Long-Term Liabilities for information regarding the associated financing obligation. Allowance for Loan Losses. The allowance for loan loss 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 (in millions) At June 30, 2023 At September 30, 2022 EnergyRight ® loan reserve $ 1 $ 1 Economic development loan collective reserve 1 1 Economic development loan specific loan reserve 1 1 Total allowance for loan losses $ 3 $ 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 June 30, 2023, and September 30, 2022, prepayments of $22 million and $12 million, respectively, were recorded in Other current assets. 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 13 — Risk Management Activities and Derivative Transactions — Derivatives Not Receiving Hedge Accounting Treatment — Commodity Contract Derivatives and — Commodity Derivatives under the FHP for a discussion of TVA's commodity contract derivatives.

Regulatory Assets and Liabiliti

Regulatory Assets and Liabilities	9 Months Ended
	Jun. 30, 2023
Regulatory Assets and Liabilities Disclosure [Abstract]
Regulatory Assets and Liabilities	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 (in millions) At June 30, 2023 At September 30, 2022 Current regulatory assets Unrealized losses on interest rate derivatives $ 32 $ 47 Unrealized losses on commodity derivatives 180 14 Fuel cost adjustment receivable 24 77 Total current regulatory assets 236 138 Non-current regulatory assets Retirement benefit plans deferred costs 1,746 1,839 Non-nuclear decommissioning costs 2,638 2,856 Unrealized losses on interest rate derivatives 473 479 Nuclear decommissioning costs 592 821 Unrealized losses on commodity derivatives 78 1 Other non-current regulatory assets 139 138 Total non-current regulatory assets 5,666 6,134 Total regulatory assets $ 5,902 $ 6,272 Current regulatory liabilities Fuel cost adjustment tax equivalents $ 203 $ 218 Unrealized gains on commodity derivatives 21 173 Total current regulatory liabilities 224 391 Non-current regulatory liabilities Retirement benefit plans deferred credits 58 70 Unrealized gains on commodity derivatives 1 102 Total non-current regulatory liabilities 59 172 Total regulatory liabilities $ 283 $ 563

Variable Interest Entities

Variable Interest Entities	9 Months Ended
	Jun. 30, 2023
Text Block [Abstract]
Variable Interest Entity Disclosure	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 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 at June 30, 2023, and September 30, 2022, as reflected on the Consolidated Balance Sheets, are as follows: Summary of Impact of VIEs on Consolidated Balance Sheets (in millions) At June 30, 2023 At September 30, 2022 Current liabilities Accrued interest $ 21 $ 10 Accounts payable and accrued liabilities 1 2 Current maturities of long-term debt of variable interest entities 35 39 Total current liabilities 57 51 Other liabilities Other long-term liabilities 17 18 Long-term debt, net Long-term debt of variable interest entities, net 951 968 Total liabilities $ 1,025 $ 1,037 Interest expense of $12 million and $13 million for the three months ended June 30, 2023 and 2022, respectively, and $36 million and $38 million for the nine months ended June 30, 2023 and 2022, respectively, is included in the Consolidated Statements of Operations related to debt of VIEs and membership interests of VIEs subject to mandatory redemption. 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	9 Months Ended
	Jun. 30, 2023
Other Liabilities, Noncurrent [Abstract]
Other Long-Term Liabilities	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 (in millions) At June 30, 2023 At September 30, 2022 (1) Interest rate swap liabilities $ 805 $ 851 Operating lease liabilities 92 93 Currency swap liabilities 153 228 Commodity contract derivative liabilities 78 1 EnergyRight ® financing obligation 55 58 Long-term deferred compensation 42 39 Advances for construction 51 53 Long-term deferred revenue 41 39 Other 108 123 Total other long-term liabilities $ 1,425 $ 1,485 Note (1) At September 30, 2022, $1 million previously classified as Other (a component of Other long-term liabilities) has been reclassified to Commodity contract derivative liabilities (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 Accounts payable and accrued liabilities, Accrued interest, and Other long-term liabilities on the Consolidated Balance Sheets. At June 30, 2023, and September 30, 2022, the carrying amount of the interest rate swap liabilities reported in Accounts payable and accrued liabilities and Accrued interest was $32 million and $54 million, respectively. See Note 13 — Risk Management Activities and Derivative Transactions — Derivatives Not Receiving Hedge Accounting Treatment — Interest Rate Derivatives 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 June 30, 2023 and September 30, 2022, the current portion of TVA's operating leases reported in Accounts payable and accrued liabilities was $66 million and $59 million, respectively. 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. At June 30, 2023 and September 30, 2022, the carrying amount of the currency swap liabilities recorded in Accounts payable and accrued liabilities was $8 million and $12 million, respectively. See Note 13 — Risk Management Activities and Derivative Transactions — Cash Flow Hedging Strategy for Currency Swaps for more information regarding the currency swap liabilities. 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 both June 30, 2023, and September 30, 2022, the carrying amount of the financing obligation reported in Accounts payable and accrued liabilities was $14 million. See Note 7 — 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 June 30, 2023 and September 30, 2022, the current amount of deferred compensation recorded in Accounts payable and accrued liabilities was $56 million and $53 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 June 30, 2023 and September 30, 2022, the current amount of advances for construction recorded in Accounts payable and accrued liabilities was $53 million and $33 million, respectively. Long-Term Deferred Revenue . Long-term deferred revenue represents payments received that exceed services rendered resulting in the deferral of revenue. The 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 reported in Accounts payable and accrued liabilities and Other long-term liabilities, respectively, on TVA’s Consolidated Balance Sheets. At June 30, 2023 and September 30, 2022, the current amount of deferred revenue recorded in Accounts payable and accrued liabilities was $11 million and $16 million, respectively.

Asset Retirement Obligations

Asset Retirement Obligations	9 Months Ended
	Jun. 30, 2023
Asset Retirement Obligation Disclosure [Abstract]
Asset Retirement Obligations	Asset Retirement Obligations During the nine months ended June 30, 2023, TVA's total asset retirement obligations ("ARO") liability decreased $40 million as a result of settlements related to retirement projects that were conducted during the period, partially offset by periodic accretion. The nuclear and non-nuclear accretion amounts were deferred as regulatory assets. During the nine months ended June 30, 2023, $141 million of the related regulatory assets were amortized into expense as these amounts were collected in rates. See Note 8 — Regulatory Assets and Liabilities . TVA maintains investment trusts to help fund its decommissioning obligations. See Note 14 — Fair Value Measurements — Investment Funds and Note 20 — Contingencies and Legal Proceedings — Contingencies — Decommissioning Costs for a discussion of the trusts' objectives and the current balances of the trusts. Asset Retirement Obligation Activity Nuclear Non-Nuclear Total Balance at September 30, 2022 $ 3,643 $ 3,519 $ 7,162 (1) Settlements — (195) (195) Revisions in estimate 6 (28) (22) Accretion (recorded as regulatory asset) 124 53 177 Balance at June 30, 2023 $ 3,773 $ 3,349 $ 7,122 (1) Note (1) Includes $262 million and $275 million at June 30, 2023, and September 30, 2022, respectively, in Current liabilities.

Debt and Other Obligations

Debt and Other Obligations	9 Months Ended
	Jun. 30, 2023
Debt Disclosure [Abstract]
Debt and Other Obligations	Debt and Other Obligations Debt Outstanding Total debt outstanding at June 30, 2023, and September 30, 2022, consisted of the following: Debt Outstanding At June 30, 2023 At September 30, 2022 Short-term debt Short-term debt, net of discounts $ 722 $ 1,172 Current maturities of power bonds issued at par 22 29 Current maturities of long-term debt of VIEs issued at par 35 39 Total current debt outstanding, net 779 1,240 Long-term debt Long-term power bonds (1) 18,990 17,950 Long-term debt of VIEs, net 951 968 Unamortized discounts, premiums, issue costs, and other (129) (124) Total long-term debt, net 19,812 18,794 Total debt outstanding $ 20,591 $ 20,034 Note (1) Includes net exchange gain from currency transactions of $89 million and $150 million at June 30, 2023, and September 30, 2022, respectively. Debt Securities Activity The table below summarizes the long-term debt securities activity for the period from October 1, 2022, to June 30, 2023: Debt Securities Activity Date Amount (in millions) Issues 2023 Series A (1) March 2023 $ 1,000 Discount on debt issues (8) Total long-term debt issues $ 992 Redemptions/Maturities (2) 2009 Series B December 2022 $ 1 2009 Series B June 2023 28 Total redemptions/maturities of power bonds 29 Debt of variable interest entities 22 Total redemptions/maturities of debt $ 51 Notes (1) The 2023 Series A Bonds were issued at 99.187 percent of par. (2) All redemptions were at 100 percent of par. Credit Facility Agreements TVA has funding available under four long-term revolving credit facilities totaling approximately $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 June 30, 2023, and September 30, 2022, there were $595 million and $704 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 13 — 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 Financial Hedging Program ("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 June 30, 2023 (in millions) Maturity Date Facility Limit Letters of Credit Outstanding Cash Borrowings Availability March 2026 (1) $ 150 $ 38 $ — $ 112 February 2025 500 302 — 198 September 2026 1,000 99 — 901 March 2027 1,000 156 — 844 Total $ 2,650 $ 595 $ — $ 2,055 Note (1) During the second quarter of 2023, TVA extended the maturity date from February 9, 2024 to March 29, 2026. 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 2023 with a maturity date of September 30, 2023. 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 June 30, 2023. The availability of this credit facility may be impacted by how the U.S. government addresses the possibility of approaching its debt limit. Lease/Leasebacks TVA previously entered into leasing transactions to obtain third-party financing for 24 peaking combustion turbine units ("CTs") as well as certain qualified technological equipment and software ("QTE"). Due to TVA's continuing involvement with the combustion turbine facilities and the QTE during the leaseback term, TVA accounted for the lease proceeds as financing obligations. There were no outstanding leaseback obligations related to the remaining CTs and QTE at June 30, 2023 and September 30, 2022. P rior to 2021, TVA made final rent payments involving 16 CTs and acquired the equity interest related to these transactions. Rent payments under the remaining CT lease/leaseback transactions were made through January 2022. In December 2021, TVA gave notice of its election to acquire the leasehold interests related to the remaining eight CTs for a total of $155 million. One associated acquisition closed in December 2022 for $78 million, and the other acquisition closed in May 2023 for $77 million. As a result, TVA recorded the cash consideration as reacquired rights, which is an intangible asset included in Completed plant on the Consolidated Balance Sheet. The amount will be amortized over the remaining estimated useful life of the underlying CTs. TVA recognized $2 million of amortization expense related to the reacquired rights within the Consolidated Statement of Operations for the nine months ended June 30, 2023. Transaction costs were not material. The estimated amortization expense for the remainder of 2023 is $1 million and will be $5 million annually from 2024 through 2052. The estimated amortization expense will be $2 million in 2053.

Risk Management Activities and

Risk Management Activities and Derivative Transactions	9 Months Ended
	Jun. 30, 2023
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Risk Management Activities and Derivative Transactions	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. Other than certain derivative instruments in its trust investment funds, it is TVA's FHP policy to enter into these derivative transactions solely for hedging purposes and not for speculative purposes. 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) (in millions) Three Months Ended June 30 Nine Months Ended June 30 Derivatives in Cash Flow Hedging Relationship Objective of Hedge Transaction Accounting for Derivative 2023 2022 2023 2022 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 $ 5 $ (40) $ 79 $ (50) 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 (in millions) Three Months Ended June 30 Nine Months Ended June 30 Derivatives in Cash Flow Hedging Relationship 2023 2022 2023 2022 Currency swaps $ 22 $ (34) $ 65 $ (50) 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 $4 million of gains from Accumulated other comprehensive income (loss) ("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) (in millions) Three Months Ended June 30 Nine Months Ended June 30 Derivative Type Objective of Derivative Accounting for Derivative Instrument 2023 2022 2023 2022 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 $ (10) $ (26) $ (36) $ (83) 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) (97) 14 (256) 14 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 assets and liabilities. As such, there were no related gains (losses) recognized in income for these unrealized gains (losses) for the three and nine months ended June 30, 2023 and for the three and nine months ended June 30, 2022. (2) Of the amount recognized for the three months ended June 30, 2023, $78 million and $19 million were reported in Fuel expense and Purchased power expense, respectively. Of the amount recognized for nine months ended June 30, 2023, $205 million and $51 million were reported in Fuel expense and Purchased power expense, respectively. Amounts recognized in 2022 were solely reported in Fuel expense. Fair Values of TVA Derivatives (in millions) At June 30, 2023 At September 30, 2022 Derivatives That Receive Hedge Accounting Treatment: Balance Balance Sheet Presentation Balance Balance Sheet Presentation Currency swaps £250 million Sterling $ (80) Accounts payable and accrued liabilities $(5); Other long-term liabilities $(75) $ (130) Accounts payable and accrued liabilities $(7); Other long-term liabilities $(123) £150 million Sterling (81) Accounts payable and accrued liabilities $(3); Other long-term liabilities $(78) (110) Accounts payable and accrued liabilities $(5); Other long-term liabilities $(105) Derivatives That Do Not Receive Hedge Accounting Treatment: Balance Balance Sheet Presentation Balance Balance Sheet Presentation Interest rate swaps $1.0 billion notional $ (619) Accounts payable and accrued liabilities $(19); Accrued interest $(6); Other long-term liabilities $(594) $ (672) Accounts payable and accrued liabilities $(9); Accrued interest $(33); Other long-term liabilities $(630) $476 million notional (218) Accounts payable and accrued liabilities $(6); Accrued interest $(1); Other long-term liabilities $(211) (233) Accounts payable and accrued liabilities $(3); Accrued interest $(9); Other long-term liabilities $(221) Commodity contract derivatives 11 Other current assets $21; Other long-term assets $1; Accounts payable and accrued liabilities $(10); Other long-term liabilities $(1) 145 Other current assets $118; Other long-term assets $34; Accounts payable and accrued liabilities $(6); Other long-term liabilities $(1) Commodity derivatives under the FHP (247) Accounts payable and accrued liabilities $(170); Other long-term liabilities $(77) 115 Accounts receivable, net $1; Other current assets $54; Other long-term assets $68; Accounts payable and accrued liabilities $(8) 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 occurre d. TVA h ad two currency swaps outstanding at June 30, 2023, with total currency exposure of £400 million and expiration dates in 2032 and 2043. 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 mark-to-market ("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 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 three months ended June 30, 2023 and 2022, the changes in fair market value of the interest rate swaps resulted in the reduction in unrealized losses of $85 million and $262 million, respectively. For the nine months ended June 30, 2023 and 2022, the changes in fair market value of the interest rate swaps resulted in the reduction in unrealized losses of $33 million and $533 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 Contract 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 power purchase agreements 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 June 30, 2023, TVA's natural gas contract derivatives had terms of up to three years. Commodity Contract Derivatives At June 30, 2023 At September 30, 2022 Number of Contracts Notional Amount Fair Value (MtM) (in millions) Number of Contracts Notional Amount Fair Value (MtM) (in millions) Natural gas contract derivatives 64 337 million mmBtu $ 18 44 296 million mmBtu $ 145 Power purchase agreement with option to settle 2 351 thousand MWh $ (7) — — thousand MWh $ — Commodity Derivatives under the FHP. In 2022, TVA reinstated the FHP, and hedging activity began under the program. 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 June 30, 2023, TVA's natural gas swap contracts under the FHP had remaining terms of up to five years. Commodity Derivatives under Financial Hedging Program (1) At June 30, 2023 At September 30, 2022 Number of Contracts Notional Amount Fair Value (MtM) (in millions) Number of Contracts Notional Amount Fair Value (MtM) (in millions) Natural gas Swap contracts 303 420 million mmBtu $ (247) 225 256 million mmBtu $ 115 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. The fair value of commodity derivatives under the FHP decreased $362 million primarily due to a decrease in forward natural gas prices at June 30, 2023 as compared to September 30, 2022. 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) (in millions) At June 30, 2023 At September 30, 2022 Assets Commodity contract derivatives $ 22 $ 152 Commodity derivatives under the FHP (2) — 123 Total derivatives subject to master netting or similar arrangement $ 22 $ 275 Liabilities Currency swaps $ 161 $ 240 Interest rate swaps (3) 837 905 Commodity contract derivatives 11 7 Commodity derivatives under the FHP (2) 247 8 Total derivatives subject to master netting or similar arrangement $ 1,256 $ 1,160 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 June 30, 2023, or September 30, 2022. (2) At June 30, 2023, the gross derivative asset and gross derivative liability was $25 million and $272 million, respectively, with offsetting amounts for each totaling $25 million. (3) Letters of credit of $569 million and $704 million were posted as collateral at June 30, 2023, and September 30, 2022, 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 Nuclear Decommissioning Trust ("NDT"), the Asset Retirement Trust ("ART"), the Supplemental Executive Retirement Plan ("SERP"), and the TVA Deferred Compensation Plan ("DCP"). See Note 14 — 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 June 30, 2023, and September 30, 2022, the NDT held investments in forward contracts to purchase debt securities. The fair values of these derivatives were in net asset positions totaling $8 million and $4 million at June 30, 2023, and September 30, 2022, respectively. 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 June 30, 2023, the aggregate fair value of all derivative instruments with credit-risk related contingent features that were in a liability position was $1.3 billion. TVA's collateral obligations at June 30, 2023, under these arrangements were $549 million, for which TVA had posted $569 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 Standard & Poor's Financial Services, LLC 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 $1.5 billion and $1.9 billion of receivables from power sales outstanding at June 30, 2023, and September 30, 2022, respectively, the majority of the counterparties were rated investment grade. The obligations of these customers that are not investment grade are secured by collateral. T VA 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 7 — Other Long-Term Assets . TVA had revenue from two LPCs that collectively accounted for 16 percent of total operating revenues for both the nine months ended June 30, 2023 and the nine months ended June 30, 2022. Suppliers . TVA assesses potential supplier performance risks, including procurement of fuel, 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 has experienced an increase in supplier impacts as a result of the state of global supply chains and the economy, such as project delays, limited availability of supplies, and price increases. Russia's invasion of Ukraine has further intensified the state of global supply chains and inflationary pressures, and TVA will continue to monitor these pressures. Natural Gas . 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 plans to continue using 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 suppliers are unable to perform under existing contracts, TVA can utilize its storage portfolio or other suppliers to help secure replacement natural gas volumes. Coal . To help ensure a reliable supply of coal, TVA had coal contracts with multiple suppliers as of June 30, 2023. 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. As a result of Russia’s invasion of Ukraine, new contracts for Russian origin nuclear fuel have been limited by Executive Order ("EO") 14066, and further restrictions on the purchase or use of Russian origin fuel may be forthcoming. TVA should have no direct impact from existing or future restrictions since TVA has no Russian origin nuclear fuel in inventory for use in its reactors and it is not contracted to purchase any Russian origin nuclear fuel. TVA could be impacted by higher market prices as a result of general market impacts associated with supply restrictions; however, at this time TVA's nuclear fuel is obtained predominantly through long-term contracts. Purchased Power . TVA acquires power from a variety of power producers through long-term and short-term power purchase agreements ("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 recent trade policy investigation into solar panel imports have created challenges for the U.S. solar industry. Both TVA's Self-Directed Solar project and existing solar PPA portfolio are 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 prices increases, and TVA terminated one PPA because of counterparty default. Derivative Counterparties . T

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Jun. 30, 2023
Fair Value Disclosures [Abstract]
Fair Value Measurements	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 and DCP 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 June 30, 2023, Investment funds were comprised of $4.2 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, and DCP. 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 $2.9 billion and $1.2 billion, respectively, at June 30, 2023. 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 NDT, ART, SERP, and DCP 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, and DCP 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, real estate investment trust securities, and cash 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. 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 $210 million, private real assets of $123 million, and private credit of $64 million at June 30, 2023. The ART had unfunded commitments related to limited partnerships in private equity of $116 million, private real assets of $61 million, and private credit of $34 million at June 30, 2023. 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, and DCP 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 8 — 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) (in millions) Three Months Ended June 30 Nine Months Ended June 30 Fund Financial Statement Presentation 2023 2022 2023 2022 NDT Regulatory assets (1) $ 51 $ (331) $ 292 $ (305) ART Regulatory assets (2) 24 (139) 145 (147) SERP Other income (expense) 2 (9) 9 (14) DCP Other income (expense) 1 (2) 2 (4) Notes (1) Includes $31 million of unrealized gains and $105 million of unrealized losses related to NDT equity securities (excluding commingled funds) for the three months ended June 30, 2023 and 2022, respectively. Includes $79 million of unrealized gains and $85 million of unrealized losses related to NDT equity securities (excluding commingled funds) for the nine months ended June 30, 2023 and 2022, respectively. (2) Includes $7 million of unrealized gains and $35 million of unrealized losses related to ART equity securities (excluding commingled funds) for the three months ended June 30, 2023 and 2022, respectively. Includes $23 million of unrealized gains and $26 million of unrealized losses related to ART equity securities (excluding commingled funds) for nine months ended June 30, 2023 and 2022, respectively. Currency and Interest Rate Swap Derivatives See Note 13 — 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. Embedded derivatives for power purchase agreements are valued based on an income approach using observable market inputs provided by an independent industry pricing 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 13 — Risk Management Activities and Derivative Transactions — Derivatives Not Receiving Hedge Accounting Treatment — Commodity Contract 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 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 2022) 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 June 30, 2023. 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 June 30, 2023, and September 30, 2022. 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 (in millions) Quoted Prices in Active Significant Other Significant Total Assets Investments Equity securities $ 658 $ — $ — $ 658 Government debt securities (1) 302 61 — 363 Corporate debt securities (2) — 444 — 444 Mortgage and asset-backed securities — 35 — 35 Institutional mutual funds 290 — — 290 Forward debt securities contracts — 8 — 8 Private equity funds measured at net asset value (3) — — — 605 Private real asset funds measured at net asset value (3) — — — 382 Private credit measured at net asset value (3) — — — 144 Commingled funds measured at net asset value (3) — — — 1,273 Total investments 1,250 548 — 4,202 Commodity contract derivatives — 22 — 22 Total $ 1,250 $ 570 $ — $ 4,224 Quoted Prices in Active Significant Other Significant Total Liabilities Currency swaps (4) $ — $ 161 $ — $ 161 Interest rate swaps — 837 — 837 Commodity contract derivatives — 11 — 11 Commodity derivatives under the FHP — 247 — 247 Total $ — $ 1,256 $ — $ 1,256 Notes (1) Includes government-sponsored entities, including $302 million of U.S. Treasury securities within Level 1 of the fair value hierarchy. (2) Includes both U.S. and foreign debt. (3) Certain investments that are measured at fair value using the NAV per share (or its equivalent) practical expedient have not been categorized in the fair value hierarchy. 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. (4) TVA records currency swaps net of cash collateral received from or paid to the counterparty if applicable, to the extent such amount is not recorded in Accounts payable and accrued liabilities. See Note 13 — Risk Management Activities and Derivative Transactions — Offsetting of Derivative Assets and Liabilities . Fair Value Measurements (in millions) Quoted Prices in Active Significant Other Significant Total Assets Investments Equity securities $ 534 $ — $ — $ 534 Government debt securities (1) 358 36 — 394 Corporate debt securities (2) — 283 — 283 Mortgage and asset-backed securities — 52 — 52 Institutional mutual funds 242 — — 242 Forward debt securities contracts — 4 — 4 Private equity funds measured at net asset value (3) — — — 487 Private real asset funds measured at net asset value (3) — — — 369 Private credit measured at net asset value (3) — — — 103 Commingled funds measured at net asset value (3) — — — 1,203 Total investments 1,134 375 — 3,671 Commodity contract derivatives — 152 — 152 Commodity derivatives under the FHP — 123 — 123 Total $ 1,134 $ 650 $ — $ 3,946 Quoted Prices in Active Significant Other Significant Total Liabilities Currency swaps (4) $ — $ 240 $ — $ 240 Interest rate swaps — 905 — 905 Commodity contract derivatives — 7 — 7 Commodity derivatives under the FHP — 8 — 8 Total $ — $ 1,160 $ — $ 1,160 Notes (1) Includes government-sponsored entities, including $358 million of U.S. Treasury securities within Level 1 of the fair value hierarchy. (2) Includes both U.S. and foreign debt. (3) Certain investments that are measured at fair value using the NAV per share (or its equivalent) practical expedient have not been categorized in the fair value hierarchy. 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. (4) TVA records currency swaps net of cash collateral received from or paid to the counterparty if applicable, to the extent such amount is not recorded in Accounts payable and accrued liabilities. See Note 13 — 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 June 30, 2023, and September 30, 2022, 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 June 30, 2023, and September 30, 2022, were as follows: Estimated Values of Financial Instruments Not Recorded at Fair Value (in millions) At June 30, 2023 At September 30, 2022 Valuation Classification Carrying Fair Carrying Fair EnergyRight ® receivables, net (including current portion) Level 2 $ 59 $ 59 $ 62 $ 62 Loans and other long-term receivables, net (including current portion) Level 2 135 127 105 96 EnergyRight ® financing obligations (including current portion) Level 2 69 78 72 81 Membership interests of VIEs subject to mandatory redemption (including current portion) Level 2 18 21 20 22 Long-term outstanding power bonds, net (including current maturities) Level 2 18,883 18,971 17,856 18,070 Long-term debt of VIEs, net (including current maturities) Level 2 986 988 1,007 989 The carrying value 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	9 Months Ended
	Jun. 30, 2023
Other Income and Expenses [Abstract]
Other Income (Expense), Net	Other Income (Expense), Net Income and expenses not related to TVA's operating activities are summarized in the following table: Other Income (Expense), Net (in millions) Three Months Ended June 30 Nine Months Ended June 30 2023 2022 2023 2022 Interest income $ 9 $ 2 $ 25 $ 9 External services 5 3 11 11 Gains (losses) on investments 5 (11) 15 (13) Miscellaneous 1 — 6 4 Other income (expense), net $ 20 $ (6) $ 57 $ 11

Benefit Plans

Benefit Plans	9 Months Ended
	Jun. 30, 2023
Retirement Benefits [Abstract]
Benefit Plans	Benefit Plans TVA sponsors a pension plan that covers most of its full-time employees hired before July 1, 2014, a qualified defined contribution plan ("401(k) plan") that covers most of its full-time employees, two unfunded post-retirement health care plans that provide for non-vested contributions toward the cost of eligible retirees' medical coverage, other post-employment benefits, such as workers' compensation, and the SERP. The pension plan and the 401(k) plan are administered by a separate legal entity, the TVA Retirement System ("TVARS"), which is governed by its own board of directors. The components of net periodic benefit cost and other amounts recognized as changes in regulatory assets for the three and nine months ended June 30, 2023 and 2022, were as follows: Components of TVA's Benefit Plans (1) (in millions) For the Three Months Ended June 30 For the Nine Months Ended June 30 Pension Benefits Other Post-Retirement Benefits Pension Benefits Other Post-Retirement Benefits 2023 2022 2023 2022 2023 2022 2023 2022 Service cost $ 8 $ 13 $ 3 $ 5 $ 24 $ 39 $ 9 $ 13 Interest cost 142 94 5 4 426 283 16 11 Expected return on plan assets (123) (108) — — (369) (326) — — Amortization of prior service credit (22) (23) (4) (5) (66) (70) (13) (13) Recognized net actuarial loss 34 97 — 2 101 294 — 5 Total net periodic benefit cost as actuarially determined 39 73 4 6 116 220 12 16 Amount expensed due to actions of regulator 19 3 — — 58 10 — — Total net periodic benefit cost $ 58 $ 76 $ 4 $ 6 $ 174 $ 230 $ 12 $ 16 Note (1) The components of net benefit cost other than the service cost component are included in Other net periodic benefit cost on the Consolidated Statements of Operations. TVA's minimum required pension plan contribution for 2023 is $300 million. TVA contributes $25 million per month to TVARS and as of June 30, 2023, had contributed $225 million. The remaining $75 million will be contributed by September 30, 2023. For the nine months ended June 30, 2023, TVA also contributed $79 million to the 401(k) plan and $19 million (net of $3 million in rebates) to the other post-retirement plans. TVA expects to contribute $6 million to the SERP in 2023.

Revenue (Notes)

Revenue (Notes)	9 Months Ended
	Jun. 30, 2023
Revenue from Contract with Customer [Abstract]
Revenue from Contract with Customer [Text Block]	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 91 percent of TVA's Revenue from sales of electricity for both the three and nine months ended June 30, 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. 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. Credits are designed to achieve objectives of the TVA Act and include items such as hydro preference credits for residential customers of LPCs, economic development credits to promote growth in the Tennessee Valley, wholesale bill credits to maintain long-term partnerships with LPCs, pandemic credits created to support LPCs and strengthen the public power response to the COVID-19 pandemic, 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. 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, pandemic credits created to support directly served customers in response to the COVID-19 pandemic, 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 the three and nine months ended June 30, 2023, revenues generated from TVA's electricity sales were $2.7 billion and $8.6 billion, respectively, and accounted for virtually all of TVA's revenues. TVA's operating revenues by state for the three and nine months ended June 30, 2023 and 2022, are detailed in the table below: Operating Revenues By State (in millions) Three Months Ended June 30 Nine Months Ended June 30 2023 2022 2023 2022 Alabama $ 388 $ 419 $ 1,244 $ 1,203 Georgia 59 69 207 207 Kentucky 172 195 562 556 Mississippi 263 283 814 788 North Carolina 17 20 67 63 Tennessee 1,754 1,929 5,613 5,455 Virginia 9 10 35 34 Subtotal 2,662 2,925 8,542 8,306 Off-system sales 2 7 9 12 Revenue from sales of electricity 2,664 2,932 8,551 8,318 Other revenue 34 38 121 119 Total operating revenues $ 2,698 $ 2,970 $ 8,672 $ 8,437 TVA's operating revenues by customer type for the three and nine months ended June 30, 2023 and 2022, are detailed in the table below: Operating Revenues by Customer Type (in millions) Three Months Ended June 30 Nine Months Ended June 30 2023 2022 2023 2022 Revenue from sales of electricity Local power companies $ 2,431 $ 2,662 $ 7,811 $ 7,576 Industries directly served 203 229 645 640 Federal agencies and other 30 41 95 102 Revenue from sales of electricity 2,664 2,932 8,551 8,318 Other revenue 34 38 121 119 Total operating revenues $ 2,698 $ 2,970 $ 8,672 $ 8,437 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 as provided for in the agreements going forward. 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 $45 million and $48 million for the three months ended June 30, 2023 and 2022, respectively. The total wholesale bill credits to LPCs participating in the partnership agreement were $140 million and $141 million for the nine months ended June 30, 2023 and 2022, respectively. 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. As of July 31, 2023, 147 LPCs had signed the partnership agreement with TVA, and 86 LPCs had signed a Power Supply Flexibility Agreement. In 2021, the TVA Board approved a 2.5 percent monthly base rate credit, the Pandemic Recovery Credit, which was effective for 2022. In 2022, the TVA Board approved a 2.5 percent monthly base rate credit, which is an extension of the Pandemic Recovery Credit, and is effective for 2023. These pandemic credits apply to service provided to TVA's LPCs, their large commercial and industrial customers, and TVA directly served customers. The 2023 credit is expected to approximate $230 million. For the three months ended June 30, 2023 and 2022, pandemic credits totaled $52 million and $56 million, respectively. For the nine months ended June 30, 2023 and 2022, pandemic credits totaled $158 million and $161 million, respectively. The number of LPCs by contract arrangement, the revenues derived from such arrangements for the three and nine months ended June 30, 2023, and the percentage those revenues comprised of TVA's total operating revenues for the same periods, are summarized in the tables below: TVA Local Power Company Contracts At or for the Three Months Ended June 30, 2023 Contract Arrangements (1) Number of LPCs Revenue from Sales of Electricity to LPCs (in millions) Percentage of Total Operating Revenues 20-year termination notice 147 $ 2,073 76.8 % 5-year termination notice 6 358 13.3 % Total 153 $ 2,431 90.1 % 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 Local Power Company Contracts At or for the Nine Months Ended June 30, 2023 Contract Arrangements (1) Number of LPCs Revenue from Sales of Electricity to LPCs (in millions) Percentage of Total Operating Revenues 20-year termination notice 147 $ 6,741 77.7 % 5-year termination notice 6 1,070 12.3 % Total 153 $ 7,811 90.0 % 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 each accounted for eight percent of TVA's total operating revenues for both the nine months ended June 30, 2023 and the nine months ended June 30, 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 June 30, 2023. 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 10 — Other Long-Term Liabilities — Long-Term Deferred Revenue .

Research and Development

Research and Development	9 Months Ended
	Jun. 30, 2023
Research and Development [Abstract]
Collaborative Arrangement Disclosure	19. Collaborative Arrangement In December 2022, TVA, Ontario Power Generation, Synthos Green Energy, 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 Statement of Operations in the period incurred. TVA recorded $6 million and $24 million of expenses related to this agreement for the three and nine months ended June 30, 2023, respectively. TVA also has a $6 million letter of credit posted under this arrangement at June 30, 2023.

Pay vs Performance Disclosure

Pay vs Performance Disclosure - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Pay vs Performance Disclosure
Net income (loss)	$ (58)	$ 256	$ 91	$ 476

Insider Trading Arrangements

Insider Trading Arrangements	3 Months Ended
	Jun. 30, 2023
Trading Arrangements, by Individual
Rule 10b5-1 Arrangement Adopted	false
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	3 Months Ended	9 Months Ended
	Jun. 30, 2023	Jun. 30, 2023
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
Fiscal Year		Fiscal Year TVA's fiscal year ends September 30. Years (2023, 2022, 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.
Basis of Presentation		Basis of Presentation TVA prepares its consolidated interim financial statements in conformity with GAAP for consolidated interim financial information. Accordingly, TVA's consolidated interim financial statements do not include all of the information and notes required by GAAP for annual financial statements. As such, they should be read in conjunction with the audited financial statements for the year ended September 30, 2022, and the notes thereto, which are contained in TVA's Annual Report on Form 10-K for the year ended September 30, 2022 (the "Annual Report"). In the opinion of management, all adjustments (consisting of items of a normal recurring nature) considered necessary for fair presentation are included on the consolidated interim financial statements. The accompanying consolidated interim 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 9 — Variable Interest Entities
Use of Estimates		Use of EstimatesThe 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, Restricted Cash and Cash Equivalents, Policy [Policy Text Block]	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. 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 (in millions) At June 30, 2023 At September 30, 2022 Cash and cash equivalents $ 500 $ 500 Restricted cash and cash equivalents included in Other long-term assets 20 20 Total cash, cash equivalents, and restricted cash $ 520 $ 520
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 June 30, 2023, and September 30, 2022, for trade accounts receivable. Additionally, loans receivable of $135 million and $105 million at June 30, 2023, and September 30, 2022, 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 $3 million at both June 30, 2023 and September 30, 2022.
Inventory, Policy	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
Revenue	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 (expense), net. 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. Colbert combustion turbine units 9-10 commenced pre-commercial plant operations in June 2023 and became operational on July 25, 2023. Estimated revenue of less than $1 million related to this project was capitalized to offset project costs for the three and nine months ended June 30, 2023. TVA also capitalized related fuel costs for this project of $1 million for the three and nine months ended June 30, 2023.
Depreciation		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 at least every five years, with the latest study implemented during the first quarter of 2022. Depreciation expense was $482 million and $459 million for the three months ended June 30, 2023 and 2022, respectively. Depreciation expense was $1.4 billion for both the nine months ended June 30, 2023 and 2022. See Note 6 — Plant Closures for a discussion of the impact of plant closures.

Accounting Changes and Error Co

Accounting Changes and Error Corrections (Policies)	9 Months Ended
	Jun. 30, 2023
Accounting Changes and Error Corrections [Abstract]
Impact of New Accounting Standards and Interpretations	The following accounting standards have been issued but, at June 30, 2023, were not effective and had not been adopted by TVA: 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 This new standard is effective for TVA’s interim and annual reporting periods beginning October 1, 2023. While early adoption is permitted, TVA does not currently plan to adopt this standard early. Effect on the Financial Statements or Other Significant Matters TVA does not expect the adoption of this standard to have a material impact on its 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 This new standard is effective for TVA’s interim and annual reporting periods beginning October 1, 2023. While early adoption is permitted, TVA does not currently plan to adopt this standard early. Effect on the Financial Statements or Other Significant Matters TVA does not expect the adoption of this standard to have a material impact on its financial condition, results of operations, or cash flows.

Deferred Costs, Capitalized, _2

Deferred Costs, Capitalized, Prepaid, and Other Assets (Policies)	9 Months Ended
	Jun. 30, 2023
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 13 — Risk Management Activities and Derivative Transactions — Derivatives Not Receiving Hedge Accounting Treatment — Commodity Contract Derivatives and — Commodity Derivatives under the FHP for a

Variable Interest Entities (Pol

Variable Interest Entities (Policies)	9 Months Ended
	Jun. 30, 2023
Text Block [Abstract]
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 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.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies Cash, Cash Equivalents, and Restricted Cash (Tables)	9 Months Ended
	Jun. 30, 2023
Cash and Cash Equivalents [Abstract]
Schedule of Cash and Cash Equivalents	Cash, Cash Equivalents, and Restricted Cash (in millions) At June 30, 2023 At September 30, 2022 Cash and cash equivalents $ 500 $ 500 Restricted cash and cash equivalents included in Other long-term assets 20 20 Total cash, cash equivalents, and restricted cash $ 520 $ 520

Impact of New Accounting Stan_2

Impact of New Accounting Standards and Interpretations Impact of New Accounting Standards and Interpretations (Tables)	9 Months Ended
	Jun. 30, 2023
Accounting Changes and Error Corrections [Abstract]
Schedule of New Accounting Pronouncements and Changes in Accounting Principles	The following accounting standards have been issued but, at June 30, 2023, were not effective and had not been adopted by TVA: 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 This new standard is effective for TVA’s interim and annual reporting periods beginning October 1, 2023. While early adoption is permitted, TVA does not currently plan to adopt this standard early. Effect on the Financial Statements or Other Significant Matters TVA does not expect the adoption of this standard to have a material impact on its 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 This new standard is effective for TVA’s interim and annual reporting periods beginning October 1, 2023. While early adoption is permitted, TVA does not currently plan to adopt this standard early. Effect on the Financial Statements or Other Significant Matters TVA does not expect the adoption of this standard to have a material impact on its financial condition, results of operations, or cash flows.

Accounts Receivable, Net (Table

Accounts Receivable, Net (Tables)	9 Months Ended
	Jun. 30, 2023
Accounts Receivable, after Allowance for Credit Loss [Abstract]
Accounts Receivable, Net	The table below summarizes the types and amounts of TVA's accounts receivable: Accounts Receivable, Net (in millions) At June 30, 2023 At September 30, 2022 Power receivables $ 1,514 $ 1,899 Other receivables 89 108 Accounts receivable, net (1) $ 1,603 $ 2,007 Note

Inventories, Net (Tables)

Inventories, Net (Tables)	9 Months Ended
	Jun. 30, 2023
Inventory, Net [Abstract]
Inventories, Net	The table below summarizes the types and amounts of TVA's inventories: Inventories, Net (in millions) At June 30, 2023 At September 30, 2022 Materials and supplies inventory $ 842 $ 808 Fuel inventory 401 303 Renewable energy certificates/emissions allowance inventory, net 17 18 Allowance for inventory obsolescence (75) (57) Inventories, net $ 1,185 $ 1,072

Deferred Costs, Capitalized, _3

Deferred Costs, Capitalized, Prepaid, and Other Assets (Tables)	9 Months Ended
	Jun. 30, 2023
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Schedule of Other Current Assets	Other current assets consisted of the following: Other Current Assets (in millions) At June 30, 2023 At September 30, 2022 (1) Commodity contract derivative assets $ 21 $ 172 Prepaid software maintenance 28 14 Prepaid insurance 26 16 Current portion of prepaid long-term service agreements 22 12 Other 64 43 Other current assets $ 161 $ 257 Note (1) At September 30, 2022, $14 million, $16 million, and $12 million previously classified as Other (a component of Other current assets) have been reclassified to Prepaid software maintenance (a component of Other current assets), Prepaid insurance (a component of Other current assets), and Current portion of prepaid long-term service agreements (a component of Other current assets), respectively, to conform with current year presentation.

Other Long-Term Assets (Tables)

Other Long-Term Assets (Tables)	9 Months Ended
	Jun. 30, 2023
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Other Long-Term Assets	The table below summarizes the types and amounts of TVA's other long-term assets: Other Long-Term Assets (in millions) At June 30, 2023 At September 30, 2022 Loans and other long-term receivables, net $ 131 $ 99 EnergyRight ® receivables, net 47 49 Prepaid long-term service agreements 57 74 Commodity contract derivative assets 1 102 Other 98 70 Total other long-term assets $ 334 $ 394

Regulatory Assets and Liabili_2

Regulatory Assets and Liabilities (Tables)	9 Months Ended
	Jun. 30, 2023
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 (in millions) At June 30, 2023 At September 30, 2022 Current regulatory assets Unrealized losses on interest rate derivatives $ 32 $ 47 Unrealized losses on commodity derivatives 180 14 Fuel cost adjustment receivable 24 77 Total current regulatory assets 236 138 Non-current regulatory assets Retirement benefit plans deferred costs 1,746 1,839 Non-nuclear decommissioning costs 2,638 2,856 Unrealized losses on interest rate derivatives 473 479 Nuclear decommissioning costs 592 821 Unrealized losses on commodity derivatives 78 1 Other non-current regulatory assets 139 138 Total non-current regulatory assets 5,666 6,134 Total regulatory assets $ 5,902 $ 6,272 Current regulatory liabilities Fuel cost adjustment tax equivalents $ 203 $ 218 Unrealized gains on commodity derivatives 21 173 Total current regulatory liabilities 224 391 Non-current regulatory liabilities Retirement benefit plans deferred credits 58 70 Unrealized gains on commodity derivatives 1 102 Total non-current regulatory liabilities 59 172 Total regulatory liabilities $ 283 $ 563

Variable Interest Entities (Tab

Variable Interest Entities (Tables)	9 Months Ended
	Jun. 30, 2023
Text Block [Abstract]
Schedule of Variable Interest Entities	The financial statement items attributable to carrying amounts and classifications of JSCCG, Holdco, and SCCG at June 30, 2023, and September 30, 2022, as reflected on the Consolidated Balance Sheets, are as follows: Summary of Impact of VIEs on Consolidated Balance Sheets (in millions) At June 30, 2023 At September 30, 2022 Current liabilities Accrued interest $ 21 $ 10 Accounts payable and accrued liabilities 1 2 Current maturities of long-term debt of variable interest entities 35 39 Total current liabilities 57 51 Other liabilities Other long-term liabilities 17 18 Long-term debt, net Long-term debt of variable interest entities, net 951 968 Total liabilities $ 1,025 $ 1,037

Other Long-Term Liabilities (Ta

Other Long-Term Liabilities (Tables)	9 Months Ended
	Jun. 30, 2023
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 (in millions) At June 30, 2023 At September 30, 2022 (1) Interest rate swap liabilities $ 805 $ 851 Operating lease liabilities 92 93 Currency swap liabilities 153 228 Commodity contract derivative liabilities 78 1 EnergyRight ® financing obligation 55 58 Long-term deferred compensation 42 39 Advances for construction 51 53 Long-term deferred revenue 41 39 Other 108 123 Total other long-term liabilities $ 1,425 $ 1,485

Asset Retirement Obligations (T

Asset Retirement Obligations (Tables)	9 Months Ended
	Jun. 30, 2023
Asset Retirement Obligation Disclosure [Abstract]
Asset Retirement Obligation Activity	Asset Retirement Obligation Activity Nuclear Non-Nuclear Total Balance at September 30, 2022 $ 3,643 $ 3,519 $ 7,162 (1) Settlements — (195) (195) Revisions in estimate 6 (28) (22) Accretion (recorded as regulatory asset) 124 53 177 Balance at June 30, 2023 $ 3,773 $ 3,349 $ 7,122 (1) Note (1) Includes $262 million and $275 million at June 30, 2023, and September 30, 2022, respectively, in Current liabilities.

Debt and Other Obligations (Tab

Debt and Other Obligations (Tables)	9 Months Ended
	Jun. 30, 2023
Debt Disclosure [Abstract]
Debt Outstanding	Total debt outstanding at June 30, 2023, and September 30, 2022, consisted of the following: Debt Outstanding At June 30, 2023 At September 30, 2022 Short-term debt Short-term debt, net of discounts $ 722 $ 1,172 Current maturities of power bonds issued at par 22 29 Current maturities of long-term debt of VIEs issued at par 35 39 Total current debt outstanding, net 779 1,240 Long-term debt Long-term power bonds (1) 18,990 17,950 Long-term debt of VIEs, net 951 968 Unamortized discounts, premiums, issue costs, and other (129) (124) Total long-term debt, net 19,812 18,794 Total debt outstanding $ 20,591 $ 20,034 Note (1) Includes net exchange gain from currency transactions of $89 million and $150 million at June 30, 2023, and September 30, 2022, respectively.
Debt Securities Activity	Debt Securities Activity The table below summarizes the long-term debt securities activity for the period from October 1, 2022, to June 30, 2023: Debt Securities Activity Date Amount (in millions) Issues 2023 Series A (1) March 2023 $ 1,000 Discount on debt issues (8) Total long-term debt issues $ 992 Redemptions/Maturities (2) 2009 Series B December 2022 $ 1 2009 Series B June 2023 28 Total redemptions/maturities of power bonds 29 Debt of variable interest entities 22 Total redemptions/maturities of debt $ 51 Notes (1) The 2023 Series A Bonds were issued at 99.187 percent of par. (2) All redemptions were at 100 percent of par.

Risk Management Activities an_2

Risk Management Activities and Derivative Transactions (Tables)	9 Months Ended
	Jun. 30, 2023
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) (in millions) Three Months Ended June 30 Nine Months Ended June 30 Derivatives in Cash Flow Hedging Relationship Objective of Hedge Transaction Accounting for Derivative 2023 2022 2023 2022 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 $ 5 $ (40) $ 79 $ (50) 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 (in millions) Three Months Ended June 30 Nine Months Ended June 30 Derivatives in Cash Flow Hedging Relationship 2023 2022 2023 2022 Currency swaps $ 22 $ (34) $ 65 $ (50) 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 $4 million of gains from Accumulated other comprehensive income (loss) ("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) (in millions) Three Months Ended June 30 Nine Months Ended June 30 Derivative Type Objective of Derivative Accounting for Derivative Instrument 2023 2022 2023 2022 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 $ (10) $ (26) $ (36) $ (83) 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) (97) 14 (256) 14 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 assets and liabilities. As such, there were no related gains (losses) recognized in income for these unrealized gains (losses) for the three and nine months ended June 30, 2023 and for the three and nine months ended June 30, 2022. (2) Of the amount recognized for the three months ended June 30, 2023, $78 million and $19 million were reported in Fuel expense and Purchased power expense, respectively. Of the amount recognized for nine months ended June 30, 2023, $205 million and $51 million were reported in Fuel expense and Purchased power expense, respectively. Amounts recognized in 2022 were solely reported in Fuel expense.
Fair Value of TVA Derivatives	Fair Values of TVA Derivatives (in millions) At June 30, 2023 At September 30, 2022 Derivatives That Receive Hedge Accounting Treatment: Balance Balance Sheet Presentation Balance Balance Sheet Presentation Currency swaps £250 million Sterling $ (80) Accounts payable and accrued liabilities $(5); Other long-term liabilities $(75) $ (130) Accounts payable and accrued liabilities $(7); Other long-term liabilities $(123) £150 million Sterling (81) Accounts payable and accrued liabilities $(3); Other long-term liabilities $(78) (110) Accounts payable and accrued liabilities $(5); Other long-term liabilities $(105) Derivatives That Do Not Receive Hedge Accounting Treatment: Balance Balance Sheet Presentation Balance Balance Sheet Presentation Interest rate swaps $1.0 billion notional $ (619) Accounts payable and accrued liabilities $(19); Accrued interest $(6); Other long-term liabilities $(594) $ (672) Accounts payable and accrued liabilities $(9); Accrued interest $(33); Other long-term liabilities $(630) $476 million notional (218) Accounts payable and accrued liabilities $(6); Accrued interest $(1); Other long-term liabilities $(211) (233) Accounts payable and accrued liabilities $(3); Accrued interest $(9); Other long-term liabilities $(221) Commodity contract derivatives 11 Other current assets $21; Other long-term assets $1; Accounts payable and accrued liabilities $(10); Other long-term liabilities $(1) 145 Other current assets $118; Other long-term assets $34; Accounts payable and accrued liabilities $(6); Other long-term liabilities $(1) Commodity derivatives under the FHP (247) Accounts payable and accrued liabilities $(170); Other long-term liabilities $(77) 115 Accounts receivable, net $1; Other current assets $54; Other long-term assets $68; Accounts payable and accrued liabilities $(8)
Commodity Contract Derivatives	Commodity Contract Derivatives At June 30, 2023 At September 30, 2022 Number of Contracts Notional Amount Fair Value (MtM) (in millions) Number of Contracts Notional Amount Fair Value (MtM) (in millions) Natural gas contract derivatives 64 337 million mmBtu $ 18 44 296 million mmBtu $ 145 Power purchase agreement with option to settle 2 351 thousand MWh $ (7) — — thousand MWh $ —
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) (in millions) At June 30, 2023 At September 30, 2022 Assets Commodity contract derivatives $ 22 $ 152 Commodity derivatives under the FHP (2) — 123 Total derivatives subject to master netting or similar arrangement $ 22 $ 275 Liabilities Currency swaps $ 161 $ 240 Interest rate swaps (3) 837 905 Commodity contract derivatives 11 7 Commodity derivatives under the FHP (2) 247 8 Total derivatives subject to master netting or similar arrangement $ 1,256 $ 1,160 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 June 30, 2023, or September 30, 2022. (2) At June 30, 2023, the gross derivative asset and gross derivative liability was $25 million and $272 million, respectively, with offsetting amounts for each totaling $25 million.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Jun. 30, 2023
Fair Value Disclosures [Abstract]
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) (in millions) Three Months Ended June 30 Nine Months Ended June 30 Fund Financial Statement Presentation 2023 2022 2023 2022 NDT Regulatory assets (1) $ 51 $ (331) $ 292 $ (305) ART Regulatory assets (2) 24 (139) 145 (147) SERP Other income (expense) 2 (9) 9 (14) DCP Other income (expense) 1 (2) 2 (4) Notes (1) Includes $31 million of unrealized gains and $105 million of unrealized losses related to NDT equity securities (excluding commingled funds) for the three months ended June 30, 2023 and 2022, respectively. Includes $79 million of unrealized gains and $85 million of unrealized losses related to NDT equity securities (excluding commingled funds) for the nine months ended June 30, 2023 and 2022, respectively. (2) Includes $7 million of unrealized gains and $35 million of unrealized losses related to ART equity securities (excluding commingled funds) for the three months ended June 30, 2023 and 2022, respectively. Includes $23 million of unrealized gains and $26 million of unrealized losses related to ART equity securities (excluding commingled funds) for nine months ended June 30, 2023 and 2022, respectively.
Fair Value Measurements	Fair Value Measurements (in millions) Quoted Prices in Active Significant Other Significant Total Assets Investments Equity securities $ 658 $ — $ — $ 658 Government debt securities (1) 302 61 — 363 Corporate debt securities (2) — 444 — 444 Mortgage and asset-backed securities — 35 — 35 Institutional mutual funds 290 — — 290 Forward debt securities contracts — 8 — 8 Private equity funds measured at net asset value (3) — — — 605 Private real asset funds measured at net asset value (3) — — — 382 Private credit measured at net asset value (3) — — — 144 Commingled funds measured at net asset value (3) — — — 1,273 Total investments 1,250 548 — 4,202 Commodity contract derivatives — 22 — 22 Total $ 1,250 $ 570 $ — $ 4,224 Quoted Prices in Active Significant Other Significant Total Liabilities Currency swaps (4) $ — $ 161 $ — $ 161 Interest rate swaps — 837 — 837 Commodity contract derivatives — 11 — 11 Commodity derivatives under the FHP — 247 — 247 Total $ — $ 1,256 $ — $ 1,256 Notes (1) Includes government-sponsored entities, including $302 million of U.S. Treasury securities within Level 1 of the fair value hierarchy. (2) Includes both U.S. and foreign debt. (3) Certain investments that are measured at fair value using the NAV per share (or its equivalent) practical expedient have not been categorized in the fair value hierarchy. 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. (4) TVA records currency swaps net of cash collateral received from or paid to the counterparty if applicable, to the extent such amount is not recorded in Accounts payable and accrued liabilities. See Note 13 — Risk Management Activities and Derivative Transactions — Offsetting of Derivative Assets and Liabilities . Fair Value Measurements (in millions) Quoted Prices in Active Significant Other Significant Total Assets Investments Equity securities $ 534 $ — $ — $ 534 Government debt securities (1) 358 36 — 394 Corporate debt securities (2) — 283 — 283 Mortgage and asset-backed securities — 52 — 52 Institutional mutual funds 242 — — 242 Forward debt securities contracts — 4 — 4 Private equity funds measured at net asset value (3) — — — 487 Private real asset funds measured at net asset value (3) — — — 369 Private credit measured at net asset value (3) — — — 103 Commingled funds measured at net asset value (3) — — — 1,203 Total investments 1,134 375 — 3,671 Commodity contract derivatives — 152 — 152 Commodity derivatives under the FHP — 123 — 123 Total $ 1,134 $ 650 $ — $ 3,946 Quoted Prices in Active Significant Other Significant Total Liabilities Currency swaps (4) $ — $ 240 $ — $ 240 Interest rate swaps — 905 — 905 Commodity contract derivatives — 7 — 7 Commodity derivatives under the FHP — 8 — 8 Total $ — $ 1,160 $ — $ 1,160 Notes (1) Includes government-sponsored entities, including $358 million of U.S. Treasury securities within Level 1 of the fair value hierarchy. (2) Includes both U.S. and foreign debt. (3) Certain investments that are measured at fair value using the NAV per share (or its equivalent) practical expedient have not been categorized in the fair value hierarchy. 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. (4) TVA records currency swaps net of cash collateral received from or paid to the counterparty if applicable, to the extent such amount is not recorded in Accounts payable and accrued liabilities. See Note 13 — 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 June 30, 2023, and September 30, 2022, were as follows: Estimated Values of Financial Instruments Not Recorded at Fair Value (in millions) At June 30, 2023 At September 30, 2022 Valuation Classification Carrying Fair Carrying Fair EnergyRight ® receivables, net (including current portion) Level 2 $ 59 $ 59 $ 62 $ 62 Loans and other long-term receivables, net (including current portion) Level 2 135 127 105 96 EnergyRight ® financing obligations (including current portion) Level 2 69 78 72 81 Membership interests of VIEs subject to mandatory redemption (including current portion) Level 2 18 21 20 22 Long-term outstanding power bonds, net (including current maturities) Level 2 18,883 18,971 17,856 18,070 Long-term debt of VIEs, net (including current maturities) Level 2 986 988 1,007 989

Other Income (Expense), Net (Ta

Other Income (Expense), Net (Tables)	9 Months Ended
	Jun. 30, 2023
Other Income and Expenses [Abstract]
Other Income (Expense), Net	16. Other Income (Expense), Net Income and expenses not related to TVA's operating activities are summarized in the following table: Other Income (Expense), Net (in millions) Three Months Ended June 30 Nine Months Ended June 30 2023 2022 2023 2022 Interest income $ 9 $ 2 $ 25 $ 9 External services 5 3 11 11 Gains (losses) on investments 5 (11) 15 (13) Miscellaneous 1 — 6 4 Other income (expense), net $ 20 $ (6) $ 57 $ 11

Benefit Plans (Tables)

Benefit Plans (Tables)	9 Months Ended
	Jun. 30, 2023
Retirement Benefits [Abstract]
Components of TVA's Benefit Plans	The components of net periodic benefit cost and other amounts recognized as changes in regulatory assets for the three and nine months ended June 30, 2023 and 2022, were as follows: Components of TVA's Benefit Plans (1) (in millions) For the Three Months Ended June 30 For the Nine Months Ended June 30 Pension Benefits Other Post-Retirement Benefits Pension Benefits Other Post-Retirement Benefits 2023 2022 2023 2022 2023 2022 2023 2022 Service cost $ 8 $ 13 $ 3 $ 5 $ 24 $ 39 $ 9 $ 13 Interest cost 142 94 5 4 426 283 16 11 Expected return on plan assets (123) (108) — — (369) (326) — — Amortization of prior service credit (22) (23) (4) (5) (66) (70) (13) (13) Recognized net actuarial loss 34 97 — 2 101 294 — 5 Total net periodic benefit cost as actuarially determined 39 73 4 6 116 220 12 16 Amount expensed due to actions of regulator 19 3 — — 58 10 — — Total net periodic benefit cost $ 58 $ 76 $ 4 $ 6 $ 174 $ 230 $ 12 $ 16 Note (1) The components of net benefit cost other than the service cost component are included in Other net periodic benefit cost on the Consolidated Statements of Operations.

Revenue (Tables)

Revenue (Tables)	3 Months Ended	9 Months Ended
	Jun. 30, 2023	Jun. 30, 2023
Revenue from Contract with Customer [Abstract]
State [Table Text Block]		TVA's operating revenues by state for the three and nine months ended June 30, 2023 and 2022, are detailed in the table below: Operating Revenues By State (in millions) Three Months Ended June 30 Nine Months Ended June 30 2023 2022 2023 2022 Alabama $ 388 $ 419 $ 1,244 $ 1,203 Georgia 59 69 207 207 Kentucky 172 195 562 556 Mississippi 263 283 814 788 North Carolina 17 20 67 63 Tennessee 1,754 1,929 5,613 5,455 Virginia 9 10 35 34 Subtotal 2,662 2,925 8,542 8,306 Off-system sales 2 7 9 12 Revenue from sales of electricity 2,664 2,932 8,551 8,318 Other revenue 34 38 121 119 Total operating revenues $ 2,698 $ 2,970 $ 8,672 $ 8,437
Revenue from External Customers by Products and Services [Table Text Block]		TVA's operating revenues by customer type for the three and nine months ended June 30, 2023 and 2022, are detailed in the table below: Operating Revenues by Customer Type (in millions) Three Months Ended June 30 Nine Months Ended June 30 2023 2022 2023 2022 Revenue from sales of electricity Local power companies $ 2,431 $ 2,662 $ 7,811 $ 7,576 Industries directly served 203 229 645 640 Federal agencies and other 30 41 95 102 Revenue from sales of electricity 2,664 2,932 8,551 8,318 Other revenue 34 38 121 119 Total operating revenues $ 2,698 $ 2,970 $ 8,672 $ 8,437
Schedule of Long-term Contracts for Purchase of Electric Power	The number of LPCs by contract arrangement, the revenues derived from such arrangements for the three and nine months ended June 30, 2023, and the percentage those revenues comprised of TVA's total operating revenues for the same periods, are summarized in the tables below: TVA Local Power Company Contracts At or for the Three Months Ended June 30, 2023 Contract Arrangements (1) Number of LPCs Revenue from Sales of Electricity to LPCs (in millions) Percentage of Total Operating Revenues 20-year termination notice 147 $ 2,073 76.8 % 5-year termination notice 6 358 13.3 % Total 153 $ 2,431 90.1 % 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 Local Power Company Contracts At or for the Nine Months Ended June 30, 2023 Contract Arrangements (1) Number of LPCs Revenue from Sales of Electricity to LPCs (in millions) Percentage of Total Operating Revenues 20-year termination notice 147 $ 6,741 77.7 % 5-year termination notice 6 1,070 12.3 % Total 153 $ 7,811 90.0 % Note

Revenue Local Power Company Con

Revenue Local Power Company Contracts (Tables)	9 Months Ended
	Jun. 30, 2023
Long-term Contract for Purchase of Electric Power [Line Items]
Long-term Contracts or Programs Disclosure [Text Block]	The number of LPCs by contract arrangement, the revenues derived from such arrangements for the three and nine months ended June 30, 2023, and the percentage those revenues comprised of TVA's total operating revenues for the same periods, are summarized in the tables below: TVA Local Power Company Contracts At or for the Three Months Ended June 30, 2023 Contract Arrangements (1) Number of LPCs Revenue from Sales of Electricity to LPCs (in millions) Percentage of Total Operating Revenues 20-year termination notice 147 $ 2,073 76.8 % 5-year termination notice 6 358 13.3 % Total 153 $ 2,431 90.1 % 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.

Summary of Significant Accoun_4

Summary of Significant Accounting Policies General and Basis of Presentation (Details) $ in Millions	Jun. 30, 2023 People	Sep. 30, 2022 USD ($)
Accounting Policies [Abstract]
Population of TVA's service area | People	10
Appropriation-investment power program | $		$ 1,000

Accounting Policies Cash and Ca

Accounting Policies Cash and Cash Equivalents (Details) - USD ($) $ in Millions	Jun. 30, 2023	Sep. 30, 2022	Jun. 30, 2022	Sep. 30, 2021
Cash and Cash Equivalents [Line Items]
Cash and Cash Equivalents, at Carrying Value	$ 500	$ 500
Restricted Cash and Cash Equivalents, Noncurrent	20	20
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	$ 520	$ 520	$ 521	$ 518

Summary of Significant Accoun_5

Summary of Significant Accounting Policies Allowance for Uncollectible Accounts (Details) - USD ($) $ in Millions	Jun. 30, 2023	Sep. 30, 2022
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for uncollectible accounts	$ 1	$ 1
Financing Receivable, after Allowance for Credit Loss	127	96
Loans and Leases Receivable, Allowance	3	3
Reported Value Measurement
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, after Allowance for Credit Loss	$ 135	$ 105

Summary of Significant Accoun_6

Summary of Significant Accounting Policies Revenues (Details) $ in Millions	9 Months Ended
	Jun. 30, 2023 USD ($) Item
Accounting Policies [Abstract]
Number of customers with billing dates before month end | Item	5
Property, Plant and Equipment [Line Items]
Pre-commercial Ops - capitalized revenue	$ 1
Pre-commercial Ops - Capitalized Fuel	$ 1

Summary of Significant Accoun_7

Summary of Significant Accounting Policies Depreciation (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2022
Property, Plant and Equipment [Line Items]
Depreciation expense	$ 482	$ 459	$ 1,400

Accounts Receivable, Net (Detai

Accounts Receivable, Net (Details) - USD ($) $ in Millions	Jun. 30, 2023	Sep. 30, 2022
Accounts Receivable, Net
Accounts Receivable, before Allowance for Credit Loss, Current	$ 1,514	$ 1,899
Other receivables	89	108
Allowance for uncollectible accounts	1	1
Accounts receivable, net	$ 1,603	$ 2,007

Inventories, Net (Details)

Inventories, Net (Details) - USD ($) $ in Millions	Jun. 30, 2023	Sep. 30, 2022
Inventories, Net
Materials and supplies inventory	$ 842	$ 808
Fuel inventory	401	303
Renewable energy certificates/emission allowance inventory, net	17	18
Allowance for inventory obsolescence	(75)	(57)
Inventories, net	$ 1,185	$ 1,072

Deferred Costs, Capitalized, _4

Deferred Costs, Capitalized, Prepaid, and Other Assets (Details) - USD ($) $ in Millions	Jun. 30, 2023	Sep. 30, 2022
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Other Assets, Miscellaneous, Current	$ 64	$ 43
Other current assets	161	257
Prepaid Insurance	26	16
Prepaid Expense, Current	22	12
Prepaid software maintenance	$ 28	$ 14

Plant Closures (Details)

Plant Closures (Details) - USD ($)	3 Months Ended		9 Months Ended		24 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022	Mar. 31, 2021
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Disposals	$ 3,000,000	$ 6,000,000	$ 11,000,000	$ 17,000,000
Accelerated depreciation	37,000,000	35,000,000	110,000,000	105,000,000	$ 592,000,000
Depreciation expense	482,000,000	$ 459,000,000		$ 1,400,000,000
Cumberland
Property, Plant and Equipment [Line Items]
Accelerated depreciation	$ 16,000,000		$ 32,000,000

Other Long-Term Assets (Details

Other Long-Term Assets (Details) - USD ($) $ in Millions	9 Months Ended
	Jun. 30, 2023	Sep. 30, 2022
Other Long-Term Assets
EnergyRight® receivables, net	$ 59	$ 62
Prepaid Expense, Noncurrent	57	74
Total other long-term assets	334	394
Prepaid Expense, Current	22	12
Loans and Leases Receivable, Allowance	3	3
Financing Receivable, after Allowance for Credit Loss, Current	4	6
EnergyRight loan reserve
Other Long-Term Assets
Loans and Leases Receivable, Allowance	1	1
Economic development loan specific 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	1	1
Accounts Receivable [Member]
Other Long-Term Assets
EnergyRight® receivables, net	12	13
Other long-term assets
Other Long-Term Assets
Loans and other long-term receivables, net	131	99
EnergyRight® receivables, net	47	49
Other	98	70
Other long-term assets
Other Long-Term Assets
Commodity Contract Asset, Noncurrent	$ 1	$ 102
Energy Right
Other Long-Term Assets
Number of days in default	180 days
Energy Right | Minimum
Other Long-Term Assets
Debt Instrument, Term	5 years
Energy Right | Maximum
Other Long-Term Assets
Debt Instrument, Term	10 years

Regulatory Assets and Liabili_3

Regulatory Assets and Liabilities (Details) $ in Millions	Jun. 30, 2023 USD ($) Units	Sep. 30, 2022 USD ($) Units
Regulatory Assets and Liabilities
Current regulatory assets	$ 236	$ 138
Non-current regulatory assets	5,666	6,134
Regulatory assets	5,902	6,272
Current regulatory liabilities	224	391
Regulatory Liability, Noncurrent	59	172
Regulatory Liabilities	283	563
Fair value	$ 78	$ 1
Power Purchase Agreement with Option to Settle
Regulatory Assets and Liabilities
Number of contracts | Units	2	0
Derivative, Nonmonetary Notional Amount	351	0
Fair value	$ (7)	$ 0
Fuel cost adjustment tax equivalents
Regulatory Assets and Liabilities
Current regulatory liabilities	203	218
Unrealized gains/losses on commodity derivatives
Regulatory Assets and Liabilities
Current regulatory liabilities	21	173
Regulatory Liability, Noncurrent	1	102
Postretirement Benefit Costs
Regulatory Assets and Liabilities
Regulatory Liability, Noncurrent	58	70
Unrealized losses on interest rate derivatives [Member]
Regulatory Assets and Liabilities
Current regulatory assets	32	47
Non-current regulatory assets	473	479
Unrealized gains/losses on commodity derivatives
Regulatory Assets and Liabilities
Current regulatory assets	180	14
Non-current regulatory assets	78	1
Fuel cost adjustment receivable/liability
Regulatory Assets and Liabilities
Current regulatory assets	24	77
Pension Costs [Member]
Regulatory Assets and Liabilities
Non-current regulatory assets	1,746	1,839
Nuclear desommissioning costs [Member]
Regulatory Assets and Liabilities
Non-current regulatory assets	592	821
Non-nuclear decommissioning [Member]
Regulatory Assets and Liabilities
Non-current regulatory assets	2,638	2,856
Other non-current regulatory assets [Member]
Regulatory Assets and Liabilities
Non-current regulatory assets	$ 139	$ 138

Variable Interest Entities Vari

Variable Interest Entities Variable Interest Entities (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022	Sep. 30, 2022	Sep. 30, 2013	Sep. 30, 2012
Variable Interest Entities
Other long-term liabilities	$ 1,425		$ 1,425		$ 1,485
Accrued interest	21		21		10
VIE Financing
Face amount	$ 40		$ 40			$ 360
Financial instruments subject to mandatory redemption, interest rate, stated percentage	7%		7%
Liabilities
Current maturities of long-term debt of variable interest entities	$ 35		$ 35		39
Long-term debt of variable interest entities, net	951		951		968
Liabilities, Current	3,948		3,948		4,645
Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entities
Other long-term liabilities	17		17		18
Liabilities	1,025		1,025		1,037		$ 1,000
Liabilities
Liabilities, Current	57		57		51
Interest Expense	12	$ 13	36	$ 38
Accounts Payable and Accrued Liabilities	$ 1		$ 1		$ 2
JSCCG
VIE Financing
Face amount							900
Holdco
VIE Financing
Face amount							$ 100
SCCG
VIE Financing
Debt and Lease Obligation						$ 400

Other Long-Term Liabilities (De

Other Long-Term Liabilities (Details) - USD ($) $ in Millions		Jun. 30, 2023	Sep. 30, 2022
Other Long-Term Liabilities
Pipeline financing obligation		$ 42	$ 39
Deferred Revenue, Noncurrent		41	39
Interest Rate Derivative Liabilities, at Fair Value		837	905
Operating Lease, Liability, Noncurrent		92	93
Currency swap liabilities	[1]	161	240
Fair value		78	1
EnergyRight® financing obligation		(78)	(81)
Other long-term liabilities		1,425	1,485
Regulatory Liability, Noncurrent		59	172
Deferred Compensation Liability, Current		56	53
Deferred Revenue, Current		11	16
Operating lease liability [Member]
Other Long-Term Liabilities
Accounts Payable and Accrued Liabilities		66	59
Accounts payable and accrued liabilities
Other Long-Term Liabilities
Interest Rate Derivative Liabilities, at Fair Value		32	54
EnergyRight® financing obligation		(14)	(14)
Customer Advances for Construction		53	33
Other long-term liabilities
Other Long-Term Liabilities
Interest Rate Derivative Liabilities, at Fair Value		805	851
Currency swap liabilities		153	228
EnergyRight® financing obligation		(55)	(58)
Other		108	123
Customer Advances for Construction		51	53
Other Current Liabilities
Other Long-Term Liabilities
Currency swap liabilities		$ 8	$ 12
[1]TVA records currency swaps net of cash collateral received from or paid to the counterparty if applicable, to the extent such amount is not recorded in Accounts payable and accrued liabilities. See Note 13 — Risk Management Activities and Derivative Transactions — Offsetting of Derivative Assets and Liabilities .

Asset Retirement Obligations (D

Asset Retirement Obligations (Details) - USD ($) $ in Millions	9 Months Ended
	Jun. 30, 2023	Sep. 30, 2022
Asset Retirement Obligations
Asset Retirement Obligation, Period Increase (Decrease)	$ (40)
Amortization and Depreciation of Decontaminating and Decommissioning Assets	141
Asset Retirement Obligation, Beginning Balance	7,162
Settlements	(195)
Asset Retirement Obligation, Revision of Estimate	(22)
Accretion (recorded as regulatory asset)	177
Asset Retirement Obligation, Ending Balance	7,122
Current portion of ARO	(262)	$ (275)
Asset Retirement Obligation, Revision of Estimate	9
Changes in closure liabilities	15
Nuclear
Asset Retirement Obligations
Asset Retirement Obligation, Beginning Balance	3,643
Settlements	0
Asset Retirement Obligation, Revision of Estimate	6
Accretion (recorded as regulatory asset)	124
Asset Retirement Obligation, Ending Balance	3,773
Non-nuclear
Asset Retirement Obligations
Asset Retirement Obligation, Beginning Balance	3,519
Settlements	(195)
Asset Retirement Obligation, Revision of Estimate	(28)
Accretion (recorded as regulatory asset)	53
Asset Retirement Obligation, Ending Balance	$ 3,349

Debt and Other Obligations Debt

Debt and Other Obligations Debt Outstanding (Details) - USD ($) $ in Millions	Jun. 30, 2023	Sep. 30, 2022
Short-term debt
Short-term debt, net	$ 722	$ 1,172
Current maturities of power bonds	22	29
Current maturities of long-term debt of variable interest entities	35	39
Total current debt outstanding, net	779	1,240
Long-term debt
Long-term power bonds	18,990	17,950
Unamortized discounts, premiums, issues costs, and other	129	124
Total long-term debt, net	19,812	18,794
Total outstanding debt	20,591	20,034
Long-term debt of variable interest entities, net	951	968
Net exchange gain from currency transaction, noncurrent	$ 89	$ 150

Debt and Other Obligations De_2

Debt and Other Obligations Debt Securities Activity (Details) - USD ($) $ in Millions		3 Months Ended	9 Months Ended
		Jun. 30, 2023	Jun. 30, 2023		Jun. 30, 2022	Sep. 30, 2022
Debt Instrument
Total long-term debt, net		$ 19,812	$ 19,812			$ 18,794
Redemptions and repurchases of power bonds			29	[1]	$ 28
Total redemptions/maturities of debt	[1]		(51)
Proceeds from Issuance of Debt			992		0
Debt Instrument, Unamortized Discount		(8)	(8)
Amount of letters of credit outstanding		$ 6	$ 6
Percent of par value		99.187%	99.187%
Long-term power bonds, net		$ 18,861	$ 18,861			$ 17,826
Repayments of Other Long-term Debt			22		$ 21
2023 Series A
Debt Instrument
Long-term power bonds, net		$ 1,000	$ 1,000
Total
Debt Instrument
Percent of par value		100%	100%
2009 Series B June Payment
Debt Instrument
Redemptions and repurchases of power bonds			$ 28
2009 Series B [Member]
Debt Instrument
Redemptions and repurchases of power bonds			$ 1
Debt of variable interest entities [Member]
Debt Instrument
Repayments of Other Long-term Debt		$ 22
[1] (1) The 2023 Series A Bonds were issued at 99.187 percent of par. (2) All redemptions were at 100 percent of par.

Debt and Other Obligations Cred

Debt and Other Obligations Credit Facility Agreements (Details)	9 Months Ended
	Jun. 30, 2023 USD ($) Credit_facilities	Sep. 30, 2022 USD ($)
Line of Credit Facility [Line Items]
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 June 30, 2023 (in millions) Maturity Date Facility Limit Letters of Credit Outstanding Cash Borrowings Availability March 2026 (1) $ 150 $ 38 $ — $ 112 February 2025 500 302 — 198 September 2026 1,000 99 — 901 March 2027 1,000 156 — 844 Total $ 2,650 $ 595 $ — $ 2,055 Note (1) During the second quarter of 2023, TVA extended the maturity date from February 9, 2024 to March 29, 2026.
Borrowings under U.S. Treasury credit facility	$ 0
February 2022 Credit Facility	1,000,000,000
Amount of letters of credit outstanding for credit facilities	6,000,000
Line of Credit
Line of Credit Facility [Line Items]
Current borrowing capacity for credit facilities	150,000,000
Revolving Credit Facilities
Line of Credit Facility [Line Items]
Current borrowing capacity for credit facilities	$ 2,650,000,000
Number of revolving credit facilities | Credit_facilities	4
December 2019 Credit Facility	$ 150,000,000
June 2020 Credit Facility	500,000,000
September 2020 Credit Facility	1,000,000,000
Cash Borrowings-December 2019 Credit Facility	0
Cash Borrowings-June 2020 Credit Facility	0
Cash Borrowings-September 2020 Credit Facility	0
Total Cash Borrowings for Credit Facilities	0
Remaining Availability, December 2019 Credit Facility	112,000,000
Remaining Availability, February 2022 Credit Facility	844,000,000
Long-term Line of Credit, Borrowings 3	0
Remaining Availability, June 2020 Credit Facility	198,000,000
Remaining Availability, September 2020 Credit Facility	901,000,000
Total Remaining Availability for Credit Facilities	2,055,000,000
Letter of Credit
Line of Credit Facility [Line Items]
Letters of Credit Outstanding, Amount 1	302,000,000
Letter of Credit Outstanding, December 2019 Credit Facility	38,000,000
Letter of Credit Outstanding, February 2022 Credit Facility	156,000,000
Letter of Credit Outstanding, September 2020 Credit Facility	99,000,000
Amount of letters of credit outstanding for credit facilities	$ 595,000,000	$ 704,000,000

Debt and Other Obligations Leas

Debt and Other Obligations Lease/Leaseback Obligations (Details) $ in Millions	3 Months Ended	6 Months Ended	9 Months Ended	12 Months Ended
	Jun. 30, 2023 USD ($)	Sep. 30, 2023 USD ($)	Jun. 30, 2023 USD ($)	Sep. 30, 2053 USD ($)	Sep. 30, 2024 USD ($)	Sep. 30, 2022
Sale Leaseback Transaction [Line Items]
CT and QTE outstanding leaseback obligation	$ 0		$ 0
Leasing transaction, number of units						16
Leasing transaction, number of units						16
CT and QTE outstanding leaseback obligation	0		0
Lagoon Creek
Sale Leaseback Transaction [Line Items]
Amortization of reacquired rights	2
Lagoon Creek | Forecast
Sale Leaseback Transaction [Line Items]
Amortization of reacquired rights		$ 1		$ 2	$ 5
Kemper/Lagoon Creek leasehold interests
Sale Leaseback Transaction [Line Items]
leasehold interest	155
leasehold interest	$ 155
Lagoon Creek
Sale Leaseback Transaction [Line Items]
leasehold interest			78
leasehold interest			78
Kemper
Sale Leaseback Transaction [Line Items]
leasehold interest			77
leasehold interest			$ 77
Kemper/Lagoon Creek leasehold interests
Sale Leaseback Transaction [Line Items]
Leasing transaction, number of units						8
Leasing transaction, number of units						8

Risk Management Activities an_3

Risk Management Activities and Derivative Transactions Derivative Instruments That Receive Hedge Accounting Treatment (Details) - USD ($) $ in Millions	3 Months Ended			9 Months Ended
	Jun. 30, 2023	Jun. 30, 2022		Jun. 30, 2023		Jun. 30, 2022
Summary of Derivative Instruments That Receive Hedge Accounting Treatment
Reclassification to earnings from cash flow hedges in the next 12 months				$ (4)
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, after Tax	$ 22	$ (34)	[1]	65	[1]	$ (50)
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), before Reclassification, after Tax	5	$ (40)		79		$ (50)
Fuel Expense | Commodity Contract under FHP
Summary of Derivative Instruments That Receive Hedge Accounting Treatment
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	78			205
Purchased Power Expense | Commodity Contract under FHP
Summary of Derivative Instruments That Receive Hedge Accounting Treatment
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	$ 19			$ 51
[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 $4 million of gains from Accumulated other comprehensive income (loss) ("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.

Risk Management Activities an_4

Risk Management Activities and Derivative Transactions Derivative Instruments That Do Not Receive Hedge Accounting Treatment (Details)	3 Months Ended			9 Months Ended
	Jun. 30, 2023 USD ($) Years	Jun. 30, 2022 USD ($)		Jun. 30, 2023 USD ($) Years		Jun. 30, 2022 USD ($)		Sep. 30, 2022 USD ($)
Derivative
Change in Unrealized gains (losses) on Interest Rate Derivatives	$ (85,000,000)	$ 262,000,000		$ (33,000,000)		$ 533,000,000
Fair value	78,000,000			78,000,000				$ 1,000,000
Increase (Decrease) in Derivative Assets				362,000,000
Interest Rate Swap
Derivative
Gain (loss) recognized in income on derivatives	(10,000,000)	(26,000,000)	[1]	(36,000,000)	[1]	(83,000,000)	[1]
Amount recognized for unrealized gains (losses)				0
Fair value	(218,000,000)			(218,000,000)				(233,000,000)
Commodity Contract Derivatives
Derivative
Fair value	$ 11,000,000			$ 11,000,000				$ 145,000,000
Natural Gas [Member]
Derivative
Number of contracts	64			64				44
Derivative, Nonmonetary Notional Amount	337,000,000			337,000,000				296,000,000
Fair value	$ 18,000,000			$ 18,000,000				$ 145,000,000
Commodity Contract under FHP
Derivative
Gain (loss) recognized in income on derivatives	$ (97,000,000)	$ 14,000,000		$ (256,000,000)		$ 14,000,000
Number of contracts	303			303				225
Derivative, Nonmonetary Notional Amount	420			420				256
Fair value	$ (247,000,000)			$ (247,000,000)				$ 115,000,000
Number Commodity Contract Term Years | Years	5			5
[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 assets and liabilities. As such, there were no related gains (losses) recognized in income for these unrealized gains (losses) for the three and nine months ended June 30, 2023 and for the three and nine months ended June 30, 2022.(2) Of the amount recognized for the three months ended June 30, 2023, $78 million and $19 million were reported in Fuel expense and Purchased power expense, respectively. Of the amount recognized for nine months ended June 30, 2023, $205 million and $51 million were reported in Fuel expense and Purchased power expense, respectively. Amounts recognized in 2022 were solely reported in Fuel expense.

Risk Management Activities an_5

Risk Management Activities and Derivative Transactions Fair Values of TVA Derivatives (Details) - USD ($) $ in Millions	Jun. 30, 2023	Sep. 30, 2022
Derivatives, Fair Value
Forward Contract Derivative Asset, at Fair Value	$ 8	$ 4
Fair value	78	1
Gross amounts of recognized liabilities	1,256	1,160
250 million Sterling currency swap
Derivatives, Fair Value
Fair value	(80)	(130)
250 million Sterling currency swap | Other long-term liabilities
Derivatives, Fair Value
Fair value	(75)	(123)
250 million Sterling currency swap | Accounts payable and accrued liabilities
Derivatives, Fair Value
Fair value	(5)	(7)
150 million Sterling currency swap
Derivatives, Fair Value
Fair value	(81)	(110)
150 million Sterling currency swap | Other long-term liabilities
Derivatives, Fair Value
Fair value	(78)	(105)
150 million Sterling currency swap | Accounts payable and accrued liabilities
Derivatives, Fair Value
Fair value	(3)	(5)
$1.0 billion notional interest rate swap
Derivatives, Fair Value
Fair value	(619)	(672)
$1.0 billion notional interest rate swap | Other long-term liabilities
Derivatives, Fair Value
Fair value	(594)	(630)
$1.0 billion notional interest rate swap | Accounts payable and accrued liabilities
Derivatives, Fair Value
Fair value	(19)	(9)
$1.0 billion notional interest rate swap | Interest payable, current
Derivatives, Fair Value
Fair value	(6)	(33)
$476 million notional interest rate swap
Derivatives, Fair Value
Fair value	(218)	(233)
$476 million notional interest rate swap | Other long-term liabilities
Derivatives, Fair Value
Fair value	(211)	(221)
$476 million notional interest rate swap | Accounts payable and accrued liabilities
Derivatives, Fair Value
Fair value	(6)	(3)
$476 million notional interest rate swap | Interest payable, current
Derivatives, Fair Value
Fair value		(9)
Commodity contract derivatives
Derivatives, Fair Value
Fair value	11	145
Commodity contract derivatives | Other long-term assets
Derivatives, Fair Value
Fair value	1	34
Commodity contract derivatives | Other current assets
Derivatives, Fair Value
Fair value	21	172
Commodity contract derivatives | Other long-term liabilities
Derivatives, Fair Value
Fair value	(1)	(1)
Commodity contract derivatives | Accounts payable and accrued liabilities
Derivatives, Fair Value
Fair value	(10)	(6)
Commodity Contract under FHP
Derivatives, Fair Value
Fair value	(247)	115
Commodity Contract under FHP | Other long-term assets
Derivatives, Fair Value
Fair value		68
Commodity Contract under FHP | Other current assets
Derivatives, Fair Value
Fair value		54
Commodity Contract under FHP | Other long-term liabilities
Derivatives, Fair Value
Fair value	(77)
Commodity Contract under FHP | Accounts payable and accrued liabilities
Derivatives, Fair Value
Fair value	(170)	(8)
Commodity Contract under FHP | Accounts Receivable [Member]
Derivatives, Fair Value
Fair value		1
Commodity Contract not under FHP | Other current assets
Derivatives, Fair Value
Fair value		118
Fair Value, Inputs, Level 2
Derivatives, Fair Value
Forward Contract Derivative Asset, at Fair Value	$ 8	$ 4

Risk Management Activities an_6

Risk Management Activities and Derivative Transactions Currency Swaps Outstanding (Details) $ in Millions	9 Months Ended
	Jun. 30, 2023 USD ($)	Sep. 30, 2022 Bond_issues
Derivative
Number of currency swaps outstanding | Bond_issues		2
Amount of letters of credit outstanding for credit facilities	$ 6
Associated TVA bond issues currency exposure	$ 400
Minimum
Derivative
Expiration date range of swaps	2032
Maximum
Derivative
Expiration date range of swaps	2043

Risk Management Activities an_7

Risk Management Activities and Derivative Transactions Derivatives Under FTP (Details) - USD ($) $ in Millions	Jun. 30, 2023	Sep. 30, 2022
Derivative
Forward Contract Derivative Asset, at Fair Value	$ 8	$ 4
Fair value	78	1
Natural Gas Contract Derivatives
Derivative
Fair value	18	145
Commodity Contract under FHP
Derivative
Fair value	(247)	115
Fair Value, Inputs, Level 2
Derivative
Forward Contract Derivative Asset, at Fair Value	$ 8	$ 4

Risk Management Activities an_8

Risk Management Activities and Derivative Transactions Offsetting of Derivative Assets (Details) - USD ($) $ in Millions	Jun. 30, 2023	Sep. 30, 2022
Offsetting Assets [Line Items]
Gross amounts of recognized liabilities	$ 1,256	$ 1,160
Total derivatives not subject to master netting or similar arrangement	22	152
Amount of letters of credit outstanding for credit facilities	6
Forward Contract Derivative Asset, at Fair Value	8	4
Derivative Liability, Not Subject to Master Netting Arrangement	11	7
Derivative Asset, Fair Value, Gross Liability	22	275
Offsetting Derivative Assets [Abstract]
Derivative, Fair Value, Amount Offset Against Collateral, Net	25
Letter of Credit
Offsetting Assets [Line Items]
Amount of letters of credit outstanding for credit facilities	595	704
Currency Swap
Offsetting Assets [Line Items]
Derivative Liability, Subject to Master Netting Arrangement, after Offset	161	240
Interest Rate Contract
Offsetting Assets [Line Items]
Gross amounts of recognized liabilities	837	905
Commodity Contract under FHP
Offsetting Assets [Line Items]
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement	272
Total derivatives not subject to master netting or similar arrangement		123
Derivative Asset, Subject to Master Netting Arrangement, after Offset	0	123
Derivative Liability, Not Subject to Master Netting Arrangement	247	8
Derivative Liability, Subject to Master Netting Arrangement, after Offset	247	8
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement	25
Fair Value, Inputs, Level 2
Offsetting Assets [Line Items]
Forward Contract Derivative Asset, at Fair Value	8	4
Fair Value, Inputs, Level 2 | Commodity Contract under FHP
Offsetting Assets [Line Items]
Total derivatives not subject to master netting or similar arrangement		123
Derivative Liability, Not Subject to Master Netting Arrangement	$ 247	$ 8

Risk Management Activities an_9

Risk Management Activities and Derivative Transactions Offsetting for Derivative Liabilities (Details) $ in Millions	Jun. 30, 2023 USD ($)	Sep. 30, 2022 USD ($) Bond_issues
Offsetting Liabilities [Line Items]
Number of currency swaps outstanding | Bond_issues		2
Accounts Receivable, before Allowance for Credit Loss, Current	$ 1,514	$ 1,899
Total derivatives not subject to master netting or similar arrangement	22	152
Gross amounts of recognized liabilities	1,256	1,160
Derivative Liability, Not Subject to Master Netting Arrangement	11	7
Amount of letters of credit outstanding	6
Forward Contract Derivative Asset, at Fair Value	8	4
Interest Rate Contract
Offsetting Liabilities [Line Items]
Gross amounts of recognized liabilities	837	905
Letter of Credit
Offsetting Liabilities [Line Items]
Amount of letters of credit outstanding	595	704
Interest Swap Collateral
Offsetting Liabilities [Line Items]
Amount of letters of credit outstanding	569
Fair Value, Inputs, Level 2
Offsetting Liabilities [Line Items]
Forward Contract Derivative Asset, at Fair Value	$ 8	$ 4

Risk Management Activities a_10

Risk Management Activities and Derivative Transactions Collateral (Details) - USD ($) $ in Millions	Jun. 30, 2023	Sep. 30, 2022
Derivative
Amount of letters of credit outstanding	$ 6
Forward Contract Derivative Asset, at Fair Value	8	$ 4
Likely cash collateral obligation increase	22
Collateralized Securities [Member]
Derivative
Derivative, Collateral, Right to Reclaim Cash	549
Letter of Credit
Derivative
Amount of letters of credit outstanding	595	704
Fair Value, Inputs, Level 2
Derivative
Forward Contract Derivative Asset, at Fair Value	$ 8	$ 4

Risk Management Activities a_11

Risk Management Activities and Derivative Transactions Counterparty Credit Risk (Details) $ in Millions	3 Months Ended	9 Months Ended
	Jun. 30, 2023 USD ($)	Jun. 30, 2023 USD ($) Customers	Sep. 30, 2022 USD ($)
Derivative
Accounts Receivable, before Allowance for Credit Loss, Current | $	$ 1,514	$ 1,514	$ 1,899
Total derivatives not subject to master netting or similar arrangement | $	$ 22	$ 22	$ 152
Two Largest Customer Percentage of Total Operating Revenue	1,600%
Moody's, A1 Rating [Member]
Derivative
Banking Counterparties Credit Rating		A2
Natural Gas Banking Counterparties Credit Rating		A1
Moody's, Caa1 Rating [Member]
Derivative
Natural Gas Banking Counterparties Credit Rating		B1
Credit of Customers
Derivative
Number of customers that represent the percent of sales | Customers		2
Number of customers that represent the percent of sales | Customers		2

Risk Management Activities a_12

Risk Management Activities and Derivative Transactions Cash Flow from Hedging (Details) $ in Millions	Jun. 30, 2023 USD ($)
Cash Flow from Hedging [Abstract]
Associated bond issues currency exposure	$ 400

Fair Value Measurements Fair Va

Fair Value Measurements Fair Value Measurements - Investments (Details) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2023 USD ($) Units	Jun. 30, 2022 USD ($)	Jun. 30, 2023 USD ($) Units	Jun. 30, 2022 USD ($)	Sep. 30, 2022 USD ($)
Investment Gains (Losses)
Financing Receivable, after Allowance for Credit Loss	$ 127		$ 127		$ 96
Balance in NDT	$ 2,900		$ 2,900
Period of time where the investor contributes capital to an investment in a private partnership - minimum | Units	3		3
Period of time where the investor contributes capital to an investment in a private partnership - maximum | Units	4		4
Minimum investment period | Units	10		10
Number of readily available quoted exchange prices for the investments	0		0
Investment funds	$ 4,202		$ 4,202		3,671
Affiliated Entity
Investment Gains (Losses)
Investment funds	302		302		$ 358
LTDCP [Member]
Investment Gains (Losses)
Unrealized gains (losses) on investments	(1)	$ 2	(2)	$ 4
SERP
Investment Gains (Losses)
Unrealized gains (losses) on investments	(2)	9	(9)	14
ART [Member]
Investment Gains (Losses)
Unrealized gains (losses) on investments	(24)	139	(145)	147
NDT [Member]
Investment Gains (Losses)
Unrealized gains (losses) on investments	(51)	$ 331	292	$ 305
Equity Funds
Investment Gains (Losses)
NDT unfunded commitments related to private equity and real estate	210		210
Real Estate Funds
Investment Gains (Losses)
NDT unfunded commitments related to private equity and real estate	123		123
Credit [Member]
Investment Gains (Losses)
NDT unfunded commitments related to private equity and real estate	64		64
Private Equity Funds [Member]
Investment Gains (Losses)
NDT unfunded commitments related to private equity and real estate	116		116
Private real estate funds [Member]
Investment Gains (Losses)
Fair value plan assets gross	61		61
Private Credit [Member]
Investment Gains (Losses)
NDT unfunded commitments related to private equity and real estate	$ 34		$ 34

Fair Value Measurements Fair _2

Fair Value Measurements Fair Value Measurements - Nonperformance Risk (Details) $ in Millions	Jun. 30, 2023 USD ($)
Nonperformance Risk
Derivative Credit Risk Valuation Adjustment, Derivative Assets	$ 1
Derivative Credit Risk Valuation Adjustment, Derivative Liabilities	$ 1

Fair Value Measurements Fair _3

Fair Value Measurements Fair Value Measurements (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022	Sep. 30, 2022
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financing Receivable, after Allowance for Credit Loss		$ 127		$ 127		$ 96
Investments
Government debt securities		363		363		394
Corporate debt securities		444		444		283
Mortgage and asset-backed securities		35		35		52
Institutional mutual funds		290		290		242
Forward debt securities contracts		8		8		4
Private credit measured at net asset value		144		144		103
Private equity funds measured at net asset value(1)		605		605		487	[1]
Private real estate funds measured at net asset value(1)		382		382		369	[1]
Commingled funds measured at net asset value(1)		1,273		1,273		1,203	[1]
Total investments		4,202		4,202		3,671
Commodity contract derivatives		22		22		152
Total derivatives not subject to master netting or similar arrangement		22		22		152
Total		4,224		4,224		3,946
Liabilities
Currency swaps	[2]	161		161		240
Interest rate swaps		837		837		905
Commodity contract derivatives		11		11		7
Derivative Liability, Not Subject to Master Netting Arrangement		11		11		7
Total		1,256		1,256		1,160
Decommissioning Fund Investments		1,200		1,200
Balance in NDT		2,900		2,900
Equity Securities, FV-NI		658		658		534
Commodity Contract under FHP
Investments
Total derivatives not subject to master netting or similar arrangement						123
Liabilities
Derivative Liability, Not Subject to Master Netting Arrangement		247		247		8
NDT [Member]
Liabilities
Debt and Equity Securities, Unrealized Gain (Loss)		31	$ 105	79	$ 85
Debt and Equity Securities, Unrealized Gain (Loss)		31	105	79	85
ART [Member]
Liabilities
Debt and Equity Securities, Unrealized Gain (Loss)		7	35	23	26
Debt and Equity Securities, Unrealized Gain (Loss)		7	$ 35	23	$ 26
Fair Value, Inputs, Level 1
Investments
Government debt securities		302		302		358
Corporate debt securities		0		0		0
Mortgage and asset-backed securities		0		0		0
Institutional mutual funds		290		290		242
Forward debt securities contracts		0		0		0
Private credit measured at net asset value		0		0		0
Private equity funds measured at net asset value(1)	[1]					0
Private real estate funds measured at net asset value(1)		0		0		0	[1]
Commingled funds measured at net asset value(1)		0		0		0	[1]
Total investments		1,250		1,250		1,134
Commodity contract derivatives		0		0		0
Total		1,250		1,250		1,134
Liabilities
Currency swaps		0		0		0	[2]
Interest rate swaps		0		0		0
Commodity contract derivatives		0		0		0
Total		0		0		0
Equity Securities, FV-NI		658		658		534
Fair Value, Inputs, Level 1 | Commodity Contract under FHP
Investments
Total derivatives not subject to master netting or similar arrangement						0
Liabilities
Derivative Liability, Not Subject to Master Netting Arrangement		0		0		0
Fair Value, Inputs, Level 2
Investments
Government debt securities		61		61		36
Corporate debt securities		444		444		283
Mortgage and asset-backed securities		35		35		52
Institutional mutual funds		0		0		0
Forward debt securities contracts		8		8		4
Private credit measured at net asset value		0		0		0
Private equity funds measured at net asset value(1)	[1]					0
Private real estate funds measured at net asset value(1)		0		0		0	[1]
Commingled funds measured at net asset value(1)		0		0		0	[1]
Total investments		548		548		375
Commodity contract derivatives		22		22		152
Total		570		570		650
Liabilities
Currency swaps		161		161		240	[2]
Interest rate swaps		837		837		905
Commodity contract derivatives		11		11		7
Total		1,256		1,256		1,160
Equity Securities, FV-NI		0		0		0
Fair Value, Inputs, Level 2 | Commodity Contract under FHP
Investments
Total derivatives not subject to master netting or similar arrangement						123
Liabilities
Derivative Liability, Not Subject to Master Netting Arrangement		247		247		8
Fair Value, Inputs, Level 3
Investments
Government debt securities		0		0		0
Corporate debt securities		0		0		0
Mortgage and asset-backed securities		0		0		0
Institutional mutual funds		0		0		0
Forward debt securities contracts		0		0		0
Private credit measured at net asset value		0		0		0
Private equity funds measured at net asset value(1)	[1]					0
Private real estate funds measured at net asset value(1)		0		0		0	[1]
Commingled funds measured at net asset value(1)		0		0		0	[1]
Total investments		0		0		0
Commodity contract derivatives		0		0		0
Total		0		0		0
Liabilities
Currency swaps		0		0		0	[2]
Interest rate swaps		0		0		0
Commodity contract derivatives		0		0		0
Total		0		0		0
Equity Securities, FV-NI		0		0		0
Fair Value, Inputs, Level 3 | Commodity Contract under FHP
Investments
Total derivatives not subject to master netting or similar arrangement						0
Liabilities
Derivative Liability, Not Subject to Master Netting Arrangement		$ 0		$ 0		$ 0
[1]Certain investments that are measured at fair value using the NAV per share (or its equivalent) practical expedient have not been categorized in the fair value hierarchy. 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. (4) TVA records currency swaps net of cash collateral received from or paid to the counterparty if applicable, to the extent such amount is not recorded in Accounts payable and accrued liabilities. See Note 13 — Risk Management Activities and Derivative Transactions — Offsetting of Derivative Assets and Liabilities . Risk Management Activities and Derivative Transactions — Offsetting of Derivative Assets and Liabilities .

Fair Value Measurements Fair _4

Fair Value Measurements Fair Value Measurements Using Significant Unobservable Inputs (Details) - USD ($) $ in Millions	Jun. 30, 2023	Sep. 30, 2022
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Commodity contract derivatives	$ 22	$ 152
Commodity contract derivatives	11	7
Fair Value, Inputs, Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Commodity contract derivatives	0	0
Commodity contract derivatives	$ 0	$ 0

Fair Value Measurements Estimat

Fair Value Measurements Estimated Values of Financial Instruments Not Recorded at Fair Value (Details) - USD ($) $ in Millions	Jun. 30, 2023	Sep. 30, 2022
Estimated Values of Financial Intruments Not Recorded at Fair Value
EnergyRight® receivables, net (including current portion)	$ 59	$ 62
Loans and other long-term receivables, net (including current portion)	127	96
EnergyRight® financing obligations (including current portion)	78	81
Membership interests of VIEs subject to mandatory redemption (including current portion)	21	22
Long-term outstanding power bonds, net (including current maturities)	18,971	18,070
Long-term debt of VIEs, net (including current maturities)	988	989
Portion at Other than Fair Value Measurement [Member]
Estimated Values of Financial Intruments Not Recorded at Fair Value
EnergyRight® receivables, net (including current portion)	59	62
EnergyRight® financing obligations (including current portion)	69	72
Membership interests of VIEs subject to mandatory redemption (including current portion)	18	20
Long-term outstanding power bonds, net (including current maturities)		17,856
Long-term debt of VIEs, net (including current maturities)	18,883	$ 1,007
Long-term notes payable (including current maturities)	$ 986

Other Income (Expense), Net (De

Other Income (Expense), Net (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Other Income (Expense), Net
External services	$ 5	$ 3	$ 11	$ 11
Interest income	9	2	25	9
Gains (losses) on investments	5	(11)	15	(13)
Miscellaneous	1	0	6	4
Other income (expense), net	$ 20	$ (6)	$ 57	$ 11

Benefit Plans Components of Ben

Benefit Plans Components of Benefit Plans (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Pension Plan
Retirement Plan Disclosure
Service cost	$ 8	$ 13	$ 24	$ 39
Interest cost	142	94	426	283
Defined Benefit Plan, Expected Return (Loss) on Plan Assets	(123)	108	(369)	326
Amortization of prior service cost	(22)	(23)	(66)	(70)
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)	34	(97)	101	(294)
Net periodic benefit cost as acutarially determined	39	73	116	220
Amount capitalized due to actions of regulator	(19)	(3)	58	10
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)	58	76	174	230
Other Postretirement Benefit Plan
Retirement Plan Disclosure
Service cost	3	5	9	13
Interest cost	5	4	16	11
Defined Benefit Plan, Expected Return (Loss) on Plan Assets	0	0	0	0
Amortization of prior service cost	(4)	(5)	(13)	(13)
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)	0	(2)	0	(5)
Net periodic benefit cost as acutarially determined	4	6	12	16
Amount capitalized due to actions of regulator	0		0	0
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)	$ 4	$ 6	12	$ 16
Defined benefit plan contributions			19
Other Pension Plan
Retirement Plan Disclosure
Defined benefit plan contributions			225
401K [Member]
Retirement Plan Disclosure
Defined benefit plan contributions			$ 79

Benefit Plans Components of Net

Benefit Plans Components of Net Periodic Benefit Cost (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Other Pension Plan
Retirement Plan Disclosure
Defined benefit plan contributions			$ 225
Pension Benefits
Retirement Plan Disclosure
Service cost	$ 8	$ 13	24	$ 39
Interest cost	142	94	426	283
Expected return on plan assets	123	(108)	369	(326)
Amortization of prior service cost	(22)	(23)	(66)	(70)
Recognized net actuarial loss	(34)	97	(101)	294
Total net periodic benefit cost as actuarially determined	39	73	116	220
Amount capitalized due to actions of regulator	19	3	(58)	(10)
Total net periodic benefit cost	58	76	174	230
Other Post-retirement Benefits
Retirement Plan Disclosure
Defined benefit plan contributions			19
Service cost	3	5	9	13
Interest cost	5	4	16	11
Expected return on plan assets	0	0	0	0
Amortization of prior service cost	(4)	(5)	(13)	(13)
Recognized net actuarial loss	0	2	0	5
Total net periodic benefit cost as actuarially determined	4	6	12	16
Amount capitalized due to actions of regulator	0		0	0
Total net periodic benefit cost	$ 4	$ 6	$ 12	$ 16

Benefit Plans Contributions (De

Benefit Plans Contributions (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Jun. 30, 2023	Jun. 30, 2023
Retirement Plan Disclosure
Remaining Employer Contributions		$ 75
Other Pension Plan
Retirement Plan Disclosure
Defined benefit plan contributions		225
defined benefit plan, plan assets, monthly contributions by employer		25
Other Post-retirement Benefits
Retirement Plan Disclosure
Defined benefit plan contributions		19
SERP
Retirement Plan Disclosure
Defined benefit plan contributions		6
Rebates [Member]
Retirement Plan Disclosure
Defined benefit plan contributions		3
401K [Member]
Retirement Plan Disclosure
Defined benefit plan contributions		$ 79
Minimum | Other Pension Plan
Retirement Plan Disclosure
Defined benefit plan contributions	$ 300

Contingencies and Legal Proceed

Contingencies and Legal Proceedings Contingencies (Details)	9 Months Ended
	Jun. 30, 2023 USD ($) reactors Procedures Insurance_layers	Sep. 30, 2022 USD ($)
Loss Contingencies
Nuclear liability insurance	$ 450,000,000
Assessment from licensees for each licensed reactor	$ 138,000,000
Number of licensed reactors in US | reactors	96
Nuclear accident assessment limitation per year per unit	$ 20,000,000
Maximum assessment per nuclear incident	963,000,000
Total amount of protection available	13,700,000,000
Amount of insurance available for loss at any one site	2,100,000,000
Maximum amount of retrospective premiums	114,000,000
Maximum idemnity if a covered accident takes or keeps a nuclear unit offline	490,000,000
Maximum retrospective premiums	44,000,000
Estimated future decommissioning cost	$ 7,122,000,000	$ 7,162,000,000
Number of procedures for determining estimates for the costs of nuclear decommissioning | Procedures	2
Possible additional future costs for compliance with Clean Air Act requirements	$ 231,000,000
Possible additional future costs for compliance with CCR requirements	711,000,000
Possible additional future costs for compliance with Clean Water requirements.	48,000,000
Estimated liability for cleanup and environmental work	16	17,000,000
Amount of insurance available for loss at any one site (top range)	2,800,000,000
Long-term debt of VIEs, net (including current maturities)	988,000,000	989,000,000
Legal loss contingency accrual	$ 28,000,000
The U.S. Congress is required to take action if these layes are exhausted | Insurance_layers	2
Nuclear
Loss Contingencies
Estimated future decommissioning cost	$ 3,773,000,000	3,643,000,000
Non-nuclear
Loss Contingencies
Estimated future decommissioning cost	$ 3,349,000,000	$ 3,519,000,000

Contingencies and Legal Proce_2

Contingencies and Legal Proceedings Legal Proceedings (Details) $ in Millions	Jun. 30, 2023 USD ($) Units
Legal Proceedings
Number of licensed nuclear units | Units	7
Legal loss contingency accrual	$ 28
Accounts payable and accrued liabilities
Legal Proceedings
Legal loss contingency accrual	18
Other Liabilities
Legal Proceedings
Legal loss contingency accrual	$ 10

Subsequent Event (Details)

Subsequent Event (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023		Jun. 30, 2022	Sep. 30, 2022
Subsequent Event [Line Items]
Redemptions and repurchases of power bonds			$ 29	[1]	$ 28
Current regulatory assets	$ 236		236			$ 138
Operating and maintenance	896	$ 722	2,546		2,269
Interest expense	264	$ 264	794		$ 791
Non-current regulatory assets	5,666		5,666			6,134
Regulatory Liability, Noncurrent	59		59			172
Unrealized gains/losses on commodity derivatives
Subsequent Event [Line Items]
Regulatory Liability, Noncurrent	1		1			102
Unrealized gains/losses on commodity derivatives
Subsequent Event [Line Items]
Current regulatory assets	180		180			14
Non-current regulatory assets	$ 78		$ 78			$ 1
[1] (1) The 2023 Series A Bonds were issued at 99.187 percent of par. (2) All redemptions were at 100 percent of par.

Gallatin Coal Combustion Residu

Gallatin Coal Combustion Residual Facilities (Details) - USD ($) $ in Millions	Jun. 30, 2023	Sep. 30, 2022
Other Long-Term Liabilities
Current regulatory assets	$ 236	$ 138

Revenue (Details)

Revenue (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022	Sep. 30, 2023
State [Line Items]
Electric revenue	$ (2,662)	$ (2,925)	$ (8,542)	$ (8,306)
Sales of Electricity	2,664	2,932	8,551	8,318
Off System Sales of Electricity	2		9	12
Other revenue	$ 34	38	$ 121	119
Total long duration contract revenue recognition	2,431		7,811
Revenues	$ 2,698	2,970	$ 8,672	8,437
Off system sales		7
Percent of wholesale Credit offered			310%
Percent of Pandemic Credit Offered			2.50%
Pandemic Relief Credit	(52)	(56)	$ (158)	(161)
Percent of Generation Flexibility Credit			5%
NES's % of operating revenues			800%
Percent of Generation Flexibility Credit			5%
Forecast
State [Line Items]
Pandemic Relief Credit					$ 230
ALABAMA
State [Line Items]
Electric revenue	(388)	(419)	$ (1,244)	(1,203)
GEORGIA
State [Line Items]
Electric revenue	(59)	(69)	(207)	(207)
KENTUCKY
State [Line Items]
Electric revenue	(172)	(195)	(562)	(556)
MISSISSIPPI
State [Line Items]
Electric revenue	(263)	(283)	(814)	(788)
NORTH CAROLINA
State [Line Items]
Electric revenue	(17)	(20)	(67)	(63)
TENNESSEE
State [Line Items]
Electric revenue	(1,754)	(1,929)	(5,613)	(5,455)
VIRGINIA
State [Line Items]
Electric revenue	(9)	$ (10)	(35)	$ (34)
20-year Termination Notice [Member]
State [Line Items]
Revenues	2,073		6,741
5-year termination notice [Member]
State [Line Items]
Revenues	$ 358		$ 1,070

Revenue Customer Type (Details)

Revenue Customer Type (Details) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Jun. 30, 2023 USD ($) Units	Jun. 30, 2022 USD ($)	Jun. 30, 2023 USD ($) Units	Jun. 30, 2022 USD ($)	Sep. 30, 2023 USD ($)
Revenue, Major Customer [Line Items]
MLGW's % of operating revenues			800%
NES's % of operating revenues			800%
Sales of Electricity	$ 2,664	$ 2,932	$ 8,551	$ 8,318
Electric revenue	2,662	2,925	8,542	8,306
Off System Sales of Electricity	2		9	12
Other revenue	34	38	121	119
Revenues	2,698	2,970	8,672	8,437
Bill credits for LTA	$ (45)	(48)	$ (140)	(141)
Number of LPCs signed LTA | Units	147		147
Number of LPCs signed Flexibility Agreement | Units	86		86
Percent of sales of electricity to LPCs	91%
Pandemic Relief Credit	$ (52)	(56)	$ (158)	(161)
Forecast
Revenue, Major Customer [Line Items]
Pandemic Relief Credit					$ 230
lpcs [Domain]
Revenue, Major Customer [Line Items]
Electric revenue	2,431	2,662	7,811	7,576
industries directly served [Domain]
Revenue, Major Customer [Line Items]
Electric revenue	203	229	645	640
federal agencies and other [Domain]
Revenue, Major Customer [Line Items]
Electric revenue	30	41	95	102
ALABAMA
Revenue, Major Customer [Line Items]
Electric revenue	388	419	1,244	1,203
GEORGIA
Revenue, Major Customer [Line Items]
Electric revenue	59	69	207	207
KENTUCKY
Revenue, Major Customer [Line Items]
Electric revenue	172	195	562	556
MISSISSIPPI
Revenue, Major Customer [Line Items]
Electric revenue	263	283	814	788
NORTH CAROLINA
Revenue, Major Customer [Line Items]
Electric revenue	17	20	67	63
TENNESSEE
Revenue, Major Customer [Line Items]
Electric revenue	1,754	1,929	5,613	5,455
VIRGINIA
Revenue, Major Customer [Line Items]
Electric revenue	$ 9	$ 10	$ 35	$ 34

Revenue Unpaid Incentives (Deta

Revenue Unpaid Incentives (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022	Sep. 30, 2022
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Paid Economic Incentives	$ 84	$ 81	$ 248	$ 249
Unpaid Economic Incentives	$ (192)		$ (192)		$ (187)

Revenue Local Power Company C_2

Revenue Local Power Company Contracts (Details) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2023 USD ($) Units	Jun. 30, 2022 USD ($)	Jun. 30, 2023 USD ($) Units	Jun. 30, 2022 USD ($)
Long-term Contract for Purchase of Electric Power [Line Items]
Long-Duration Contracts Revenue Recognition, Policy [Policy Text Block]	$ 2,698	$ 2,970	$ 8,672	$ 8,437
Total long-duration contracts revenue recognition	2,431		7,811
Total percentage of operating revenues	90.10%		90%
Number of LPCs signed LTA | Units	147		147
Total Number of LPCs | Units	153		153
5-year Termination Notice [Member]
Long-term Contract for Purchase of Electric Power [Line Items]
Long-Duration Contracts Revenue Recognition, Policy [Policy Text Block]	$ 358		$ 1,070
Percentage of total operating revenues	13.30%		12.30%
Number of LPCs signed LTA | Units	6		6
20-year Termination Notice [Member]
Long-term Contract for Purchase of Electric Power [Line Items]
Long-Duration Contracts Revenue Recognition, Policy [Policy Text Block]	$ 2,073		$ 6,741
Percentage of total operating revenues	76.80%		77.70%

Leases (Details)

Leases (Details) - USD ($) $ in Millions	Jun. 30, 2023	Sep. 30, 2022
Amounts Recognized on TVA's Consolidated Balance Sheet [Line Items]
Finance lease, asset	$ 584	$ 630
Operating Lease, Liability, Noncurrent	92	93
Finance Lease, Liability, Noncurrent	$ 594	$ 628

Research and Development (Detai

Research and Development (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended	48 Months Ended
	Jun. 30, 2023	Jun. 30, 2023	Sep. 30, 2026
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Other Research and Development Expense	$ 6	$ 24
Forecast
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Other Research and Development Expense			$ 88