Tennessee Valley Authority PARRS A 2029 (TVE) 10-Q 3 Feb 16 2016 Q1 Quarterly report Financial data

DEI Document

DEI Document shares in Millions, $ in Millions	3 Months Ended
	Dec. 31, 2015USD ($)shares
Document Information [Line Items]
Entity Registrant Name	Tennessee Valley Authority
Entity Central Index Key	1,376,986
Current Fiscal Year End Date	--09-30
Entity Filer Category	Non-accelerated Filer
Document Type	10-Q
Document Period End Date	Dec. 31, 2015
Document Fiscal Year Focus	2,016
Document Fiscal Period Focus	Q1
Amendment Flag	false
Entity Common Stock, Shares Outstanding | shares	0
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float | $	$ 0

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS (UNAUDITED) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Operating revenues
Revenue from sales of electricity	$ 2,246	$ 2,375
Other revenue	34	36
Total operating revenues	2,280	2,411
Operating expenses
Fuel	480	550
Purchased power	247	233
Operating and maintenance	740	688
Depreciation and amortization	461	452
Tax equivalents	124	124
Total operating expenses	2,052	2,047
Operating income	228	364
Other income (expense), net	12	9
Interest expense
Interest expense	335	342
Allowance for funds used during construction	(58)	(50)
Net interest expense	277	292
Net income (loss)	$ (37)	$ 81

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (UNAUDITED) - USD ($) $ in Millions		3 Months Ended
		Dec. 31, 2015	Dec. 31, 2014
Net income (loss)		$ (37)	$ 81
Other comprehensive income (loss)
Net unrealized gain (loss) on cash flow hedges		(27)	(15)
Reclassification to earnings from cash flow hedges	[1]	24	38
Total other comprehensive income (loss)		(3)	23
Total comprehensive income (loss)		$ (40)	$ 104
[1]	There were no ineffective portions or amounts excluded from effectiveness testing for any of the periods presented. Based on forecasted foreign currency exchange rates, TVA expects to reclassify approximately $44 million of losses from AOCI to interest expense within the next twelve months to offset amounts anticipated to be recorded in interest expense related to exchange gain on the debt.

CONSOLIDATED BALANCE SHEETS (UN

CONSOLIDATED BALANCE SHEETS (UNAUDITED) - USD ($) $ in Millions	Dec. 31, 2015	Sep. 30, 2015
Current assets
Cash and cash equivalents	$ 311	$ 300
Restricted cash and investments	20	15
Accounts receivable, net	1,239	1,600
Inventories, net	1,146	1,031
Regulatory assets	503	506
Other current assets	65	54
Total current assets	3,284	3,506
Property, plant, and equipment
Completed plant	50,457	50,069
Less accumulated depreciation	(26,653)	(26,318)
Net completed plant	23,804	23,751
Construction in progress	7,413	7,147
Nuclear fuel	1,409	1,415
Capital leases	102	94
Total property, plant, and equipment, net	32,728	32,407
Investment funds	2,083	2,011
Regulatory and other long-term assets
Regulatory assets	10,237	10,418
Other long-term assets	410	403
Total regulatory and other long-term assets	10,647	10,821
Total assets	48,742	48,745
Current liabilities
Accounts payable and accrued liabilities	1,814	2,127
Accrued interest	344	366
Current portion of leaseback obligations	79	79
Current portion of energy prepayment obligations	100	100
Regulatory liabilities	182	164
Short-term debt, net	1,504	1,034
Current maturities of power bonds	554	32
Current maturities of long-term debt of variable interest entities	33	33
Total current liabilities	4,610	3,935
Other liabilities
Post-retirement and post-employment benefit obligations	7,124	7,107
Asset retirement obligations	3,668	3,682
Other long-term liabilities	2,149	2,219
Leaseback obligations	537	537
Energy prepayment obligations	185	210
Regulatory liabilities	4	2
Total other liabilities	13,667	13,757
Long-term debt, net
Long-term power bonds, net	22,071	22,617
Long-term debt of variable interest entities, net	1,233	1,233
Total long-term debt, net	23,304	23,850
Total liabilities	41,581	41,542
Proprietary capital
Power program appropriation investment	258	258
Power program retained earnings	6,321	6,357
Total power program proprietary capital	6,579	6,615
Nonpower programs appropriation investment, net	587	590
Accumulated other comprehensive income (loss)	(5)	(2)
Total proprietary capital	7,161	7,203
Total liabilities and proprietary capital	$ 48,742	$ 48,745

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Cash flows from operating activities
Net income (loss)	$ (37)	$ 81
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)	472	463
Amortization of nuclear fuel cost	63	72
Non-cash retirement benefit expense	82	84
Prepayment credits applied to revenue	(25)	(25)
Fuel cost adjustment deferral	37	(6)
Fuel cost tax equivalents	(7)	(9)
Changes in current assets and liabilities
Accounts receivable, net	375	311
Inventories and other, net	(104)	(120)
Accounts payable and accrued liabilities	(246)	(348)
Accrued interest	(22)	(42)
Regulatory assets costs	(11)	(12)
Insurance recoveries	7	50
Other, net	(68)	(26)
Net cash provided by operating activities	516	473
Cash flows from investing activities
Construction expenditures	(866)	(751)
Nuclear fuel expenditures	(101)	(219)
Loans and other receivables
Advances	(2)	(10)
Repayments	1	2
Other, net	0	(20)
Net cash used in investing activities	(968)	(998)
Long-term debt
Redemptions and repurchases of power bonds	(4)	(4)
Short-term debt issues (redemptions), net	470	521
Payments on leases and leasebacks	(2)	(2)
Payments to U.S. Treasury	(2)	(1)
Other, net	1	10
Net cash provided by (used in) financing activities	463	524
Net change in cash and cash equivalents	11	(1)
Cash and cash equivalents at beginning of period	300	500
Cash and cash equivalents at end of period	311	499
Significant non-cash transactions
Capital Expenditures Incurred but Not yet Paid	$ 372	$ 237

CONSOLIDATED STATEMENTS OF CHAN

CONSOLIDATED STATEMENTS OF CHANGES IN PROPRIETARY CAPITAL (UNAUDITED) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Sep. 30, 2015	Sep. 30, 2014
Appropriation-investment power program	$ 258		$ 258
Net income (loss)	(37)	$ 81
Total other comprehensive income (loss)	(3)	23
Return on power program appropriation investment	(2)	(1)
Retained Earnings Power Program	6,321		6,357
Appropriation investment nonpower programs, net	587		590
Accumulated Other Comprehensive Income (Loss) from Net Gains (Losses) on Cash Flow Hedges	(5)		(2)
Proprietary Capital	7,161	6,207	7,203	$ 6,104
Power Program Appropriation Investment
Appropriation-investment power program	258	258	258	258
Net income (loss)	0	0
Total other comprehensive income (loss)	0	0
Return on power program appropriation investment	0	0
Power Program Retained Earnings
Net income (loss)	(34)	84
Total other comprehensive income (loss)	0	0
Return on power program appropriation investment	(2)	(1)
Retained Earnings Power Program	6,321	5,323	6,357	5,240
Nonpower Programs Appropriation Investment, Net
Net income (loss)	(3)	(3)
Total other comprehensive income (loss)	0	0
Return on power program appropriation investment	0	0
Appropriation investment nonpower programs, net	587	598	590	601
Accumulated Other Comprehensive Income (Loss) from Net Gains (Losses) on Cash Flow Hedges
Net income (loss)	0	0
Total other comprehensive income (loss)	(3)	23
Return on power program appropriation investment	0	0
Accumulated Other Comprehensive Income (Loss) from Net Gains (Losses) on Cash Flow Hedges	$ (5)	$ 28	$ (2)	$ 5

Summary of Significant Accounti

Summary of Significant Accounting Policies	3 Months Ended
	Dec. 31, 2015
Accounting Policies [Abstract]
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 that was created in 1933 by legislation enacted by the United States ("U.S.") Congress in response to a request 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 United States, 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 nine 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 to provide recreational opportunities, adequate water supply, improved water quality, natural resource protection, and economic development. 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 ("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 of Directors (the "TVA Board") as authorized by the Tennessee Valley Authority Act of 1933, as amended, 16 U.S.C. §§ 831-831ee (the “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. 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. TVA fulfilled its requirement to repay $ 1.0 billion of the Power Program Appropriation Investment in 2014. Fiscal Year TVA's fiscal year ends September 30. Years ( 2016 , 2015 , 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 future 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 any of the other factors described above cease to be applicable, TVA would no longer be considered to be a regulated entity and would be required to write off these costs. Most 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, 2015 , and the notes thereto, which are contained in TVA's Annual Report on Form 10-K for the year ended September 30, 2015 (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 in the interim financial statements. The accompanying consolidated interim financial statements include the accounts of TVA and three variable interest entities ("VIEs") , of which TVA is the primary beneficiary. See Note 7 . 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 deemed 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. Reclassifications Certain historical amounts have been reclassified in the Consolidated Statements of Cash Flows for the three months ended December 31, 2014 . Amounts previously presented in Cash flows from operating activities as Environmental cleanup costs – Kingston ash spill – non cash of $ 12 million and Environmental cleanup costs – Kingston ash spill of $ (9) million for the three months ended December 31, 2014 , are currently reported in Other, net. In the Consolidated Balance Sheet at September 30, 2015 , TVA reclassified $80 million of debt issuance costs previously presented in Other long-term assets and presented $67 million as a reduction to Long-term power bonds, net and $13 million as a reduction to Long-term debt, net of variable interest entities. See Note 2 – Debt Issuance Costs for additional information. Allowance for Uncollectible Accounts The allowance for uncollectible accounts reflects TVA's estimate of probable losses inherent in its accounts and loans receivable balances. TVA determines the allowance based on known accounts, historical experience, and other currently available information including events such as customer bankruptcy and/or a customer failing to fulfill payment arrangements. It also reflects TVA's corporate credit department's assessment of the financial condition of customers and the credit quality of the receivables. The allowance for uncollectible accounts was $ 1 million at both December 31, 2015 and September 30, 2015 , for accounts receivable. Additionally, loans receivable of $ 135 million and $ 129 million at December 31, 2015 and September 30, 2015 , respectively, are included in Accounts receivable, net and Other long-term assets, for the current and long-term portions, respectively, and reported net of allowances for uncollectible accounts of $ 8 million at both December 31, 2015 and September 30, 2015 . Depreciation Depreciation expense was $ 364 million and $ 380 million for the three months ended December 31, 2015 , and December 31, 2014 , respectively. In September 2015, the NRC approved renewed licenses for Sequoyah Nuclear Plant ("Sequoyah") Units 1 and 2, which allow both units to operate for an additional 20 years and TVA adjusted prospectively the Sequoyah depreciation rate. These license extensions contributed to $22 million of the decrease in depreciation expense for the three months ended December 31, 2015, as compared to the three months ended December 31, 2014 as a result of this change in estimate. Blended Low-Enriched Uranium Program Under the blended low-enriched uranium ("BLEU") program, TVA, the U.S. Department of Energy ("DOE") , and certain nuclear fuel contractors have entered into agreements providing for the DOE's surplus of enriched uranium to be blended with other uranium down to a level that allows the blended uranium to be fabricated into fuel that can be used in nuclear power plants. Under the terms of an interagency agreement between TVA and the DOE, in exchange for supplying highly enriched uranium materials to the appropriate third-party fuel processors for processing into usable BLEU fuel for TVA, the DOE participates to a degree in the savings generated by TVA’s use of this blended nuclear fuel. Over the life of the program, TVA projects that the DOE’s share of savings generated by TVA’s use of this blended nuclear fuel could result in payments to the DOE of as much as $ 162 million . TVA accrues an obligation with each BLEU reload batch related to the portion of the ultimate future payments estimated to be attributable to the BLEU fuel currently in use. At December 31, 2015 , TVA had paid out approximately $ 131 million for this program, and the obligation recorded was $ 12 million .

Impact of New Accounting Standa

Impact of New Accounting Standards and Interpretations	3 Months Ended
	Dec. 31, 2015
Accounting Changes and Error Corrections [Abstract]
Impact of New Accounting Standards and Interpretations	Impact of New Accounting Standards and Interpretations The following accounting standard was adopted by TVA on October 1, 2015. Debt Issuance Costs . In April 2015, the Financial Accounting Standards Board ("FASB") issued guidance that changes the presentation of debt issuance costs in financial statements. This standard requires that debt issuance costs related to a recognized debt liability be presented in the balance sheet as a direct reduction of that debt liability, consistent with debt discounts, including retrospectively adjusting all prior periods presented. TVA early adopted the standard on October 1, 2015. In the Consolidated Balance Sheets at December 31, 2015, TVA reclassified $80 million of debt issuance costs previously presented in Other long-term assets on the September 30, 2015 Consolidated Balance Sheets and presented these amounts as a reduction to Long-term power bonds, net and Long-term debt, net of variable interest entities. The guidance does not change the recognition and measurement of debt issuance costs. The following accounting standards have been issued, but as of December 31, 2015 , were not effective and had not been adopted by TVA. Revenue Recognition . In May 2014, the FASB issued a new revenue recognition standard that applies to revenue from contracts with customers. The standard requires that an entity recognize revenue to depict the transfer of goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. In August 2015, the FASB issued a one-year deferral of the effective date. The standard becomes effective for TVA on October 1, 2018, and allows for either a full retrospective or a modified retrospective application. Early adoption of the standard is permitted for TVA on October 1, 2017. TVA is currently evaluating the potential impact of these changes on its consolidated financial statements and related disclosures and the application method to be used. Consolidation. In February 2015, the FASB issued guidance that amends the consolidation analysis for VIEs as well as voting interest entities. The standard reduces the number of consolidation models through the elimination of the indefinite deferral for certain entities that was previously allowed and places more emphasis on risk of loss when determining a controlling financial interest. The standard becomes effective for TVA on October 1, 2016, and allows for either a full retrospective or a modified retrospective application. TVA has evaluated the impact of adopting this guidance and expects no material impact on TVA's financial condition, results of operations, or cash flows. Inventory Valuation . In July 2015, the FASB issued guidance that changes the model used for the subsequent measurement of inventory from the previous lower of cost or market model, to the lower of cost or net realizable value. The guidance applies only to inventory valued using methods other than last-in, first out or the retail inventory method (for example, first-in, first-out or average cost). This amendment is intended to simplify the subsequent measurement of inventory. The standard becomes effective for TVA on October 1, 2017, including interim periods within the fiscal year that begins on that date, and is required to be applied prospectively. Early adoption is permitted. TVA is currently evaluating the potential impact of these changes on its consolidated financial statements.

Accounts Receivable, Net

Accounts Receivable, Net	3 Months Ended
	Dec. 31, 2015
Accounts Receivable, Net [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 At December 31, 2015 At September 30, 2015 Power receivables $ 1,165 $ 1,509 Other receivables 75 92 Allowance for uncollectible accounts (1 ) (1 ) Accounts receivable, net $ 1,239 $ 1,600

Inventories, Net

Inventories, Net	3 Months Ended
	Dec. 31, 2015
Inventory, Net [Abstract]
Inventories, Net	Inventories, Net The table below summarizes the types and amounts of TVA’s inventories: Inventories, Net At December 31, 2015 At September 30, 2015 Materials and supplies inventory $ 685 $ 651 Fuel inventory 499 414 Emission allowance inventory, net 15 13 Allowance for inventory obsolescence (53 ) (47 ) Inventories, net $ 1,146 $ 1,031

Other Long-Term Assets

Other Long-Term Assets	3 Months Ended
	Dec. 31, 2015
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 At December 31, 2015 At September 30, 2015 EnergyRight ® receivables $ 123 $ 124 Loans and other long-term receivables, net 132 126 Prepaid capacity payments 50 52 Currency swap asset, net 9 25 Commodity contract derivative assets 4 1 Other 92 75 Other long-term assets $ 410 $ 403 In association with the EnergyRight ® Solutions program, local power company customers of TVA ("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 ten 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 loan receivable that has been in default for 180 days or more or that TVA has determined is 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. As of both December 31, 2015 and September 30, 2015 , the carrying amount of the loans receivable, net of discount, reported in Accounts receivable, net was approximately $ 32 million . See Note 8 for information regarding the associated financing obligation.

Regulatory Assets and Liabiliti

Regulatory Assets and Liabilities	3 Months Ended
	Dec. 31, 2015
Regulatory Assets and Liabilities Disclosure [Abstract]
Regulatory Assets and Liabilities	Regulatory Assets and 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 deferrals of gains that will be credited to customers in future periods. Components of regulatory assets and regulatory liabilities are summarized in the table below: Regulatory Assets and Liabilities At December 31, 2015 At September 30, 2015 Current regulatory assets Deferred nuclear generating units $ 237 $ 237 Unrealized losses on commodity derivatives 169 162 Environmental agreements 49 47 Environmental cleanup costs - Kingston ash spill 43 43 Fuel cost adjustment receivable 3 15 Other current regulatory assets 2 2 Total current regulatory assets 503 506 Non-current regulatory assets Deferred pension costs and other post-retirement benefits costs 5,556 5,565 Unrealized losses on interest rate derivatives 1,147 1,236 Nuclear decommissioning costs 970 1,003 Environmental cleanup costs - Kingston ash spill 331 348 Non-nuclear decommissioning costs 835 828 Deferred nuclear generating units 1,004 1,042 Environmental agreements 41 55 Unrealized losses on commodity derivatives 81 63 Other non-current regulatory assets 272 278 Total non-current regulatory assets 10,237 10,418 Total regulatory assets $ 10,740 $ 10,924 Current regulatory liabilities Fuel cost adjustment tax equivalents $ 157 $ 164 Fuel cost adjustment payable 25 — Total current regulatory liabilities 182 164 Non-current regulatory liabilities Unrealized gains on commodity derivatives 4 2 Total non-current regulatory liabilities 4 2 Total regulatory liabilities $ 186 $ 166

Variable Interest Entities

Variable Interest Entities	3 Months Ended
	Dec. 31, 2015
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Variable Interest Entities	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 variable interest entity, 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 several entities and as such is required to account for the VIEs on a consolidated basis. See discussion following. John Sevier VIE 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 is 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 scheduled 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. Southaven VIE In 2013, TVA entered into a 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 of 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 7.0 percent , which is reflected as interest expense in the consolidated statements of operations. SHLLC is required to pay a pre-determined portion of the return on investment to Seven States Southaven, LLC ("SSSL") on each lease payment date as agreed in SHLLC's formation documents (the "Seven States Return"). The current and long-term portions of the Membership interests of VIE subject to mandatory redemption are included in Accounts payable and accrued liabilities and Other long-term liabilities, respectively. The payment dates for the mandatorily redeemable membership interests are the same as those of the SHLLC notes. The SCCG notes are secured by TVA’s lease payments, and the SHLLC notes are secured by SHLLC’s investment in, and amounts receivable from, SCCG. TVA’s lease payments to SCCG are payable on the same dates as SCCG’s and SHLLC’s semi-annual debt service payments and are equal to the sum of (i) the amount of SCCG’s semi-annual debt service payments, (ii) the amount of SHLLC’s semi-annual debt service payments, and (iii) the amount of the Seven States Return. In addition to the lease payments, TVA pays administrative and miscellaneous expenses incurred by SCCG and SHLLC. Certain agreements related to this transaction contain default and acceleration provisions. In the event that TVA were to choose to exercise an early buy out feature of the Southaven Facility Lease, in part or in whole, TVA must pay to SCCG amounts sufficient for SCCG to repay or partially repay on a pro rata basis the membership interests held by SHLLC, including any outstanding investment amount plus accrued but unpaid return. TVA also has the right, at any time and without any early redemption of the other portions of the Southaven Facility Lease payments due to SCCG, to fully repay SHLLC's investment, upon which repayment SHLLC will transfer the membership interests to a designee of TVA. Impact on Consolidated Balance Sheets The financial statement items attributable to carrying amounts and classifications of JSCCG, Holdco, and SCCG as of December 31, 2015 and September 30, 2015 , as reflected in the consolidated balance sheets are as follows: Summary of Impact of VIEs on Consolidated Balance Sheets At December 31, 2015 At September 30, 2015 Current liabilities of VIE Accrued interest of VIE $ 27 $ 12 Current portion of membership interests of VIE subject to mandatory redemption 2 2 Current maturities of long-term debt of VIE 33 33 Total current liabilities of VIE 62 47 Other liabilities of VIE Membership interests of VIE subject to mandatory redemption 35 35 Long-term debt of VIE, net Long-term debt of VIE, net 1,233 1,233 Total liabilities of VIE $ 1,330 $ 1,315 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	3 Months Ended
	Dec. 31, 2015
Other Liabilities, Noncurrent [Abstract]
Other Long-Term Liabilities	Other Long-Term Liabilities Other long-term liabilities consist primarily of liabilities related to certain derivative instruments as well as liabilities under agreements related to compliance with certain environmental regulations (see Note 16 — Legal Proceedings — Environmental Agreements ). The table below summarizes the types and amounts of Other long-term liabilities: Other Long-Term Liabilities At December 31, 2015 At September 30, 2015 Interest rate swap liabilities $ 1,538 $ 1,627 EnergyRight ® financing obligation 146 148 Environmental agreements liability 41 55 Currency swap liabilities 58 47 Membership interests of VIE subject to mandatory redemption 35 35 Commodity contract derivative liabilities 46 17 Commodity swap derivative liabilities 9 10 Other 276 280 Total other long-term liabilities $ 2,149 $ 2,219 EnergyRight ® Financing Obligation . TVA purchases certain loans receivable from its LPCs in association with the EnergyRight ® Solutions 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. As of both December 31, 2015 and September 30, 2015 , the carrying amount of the financing obligation reported in Accounts payable and accrued liabilities was approximately $ 37 million . See Note 5 for information regarding the associated loans receivable and for details regarding the EnergyRight ® Solutions program.

Asset Retirement Obligations

Asset Retirement Obligations	3 Months Ended
	Dec. 31, 2015
Asset Retirement Obligation Disclosure [Abstract]
Asset Retirement Obligations	Asset Retirement Obligations During the three months ended December 31, 2015 , TVA's total ARO liability increased $ 8 million . To estimate its decommissioning obligation related to its nuclear generating stations, TVA uses a probability-weighted, discounted cash flow model which, on a unit-by-unit basis, considers multiple outcome scenarios that include significant estimations and assumptions. Those assumptions include (1) estimates of the cost of decommissioning, (2) the method of decommissioning and the timing of the related cash flows, (3) the license period of the nuclear plant, considering the probability of license extensions, (4) cost escalation factors, and (5) the credit adjusted risk free rate to measure the obligation at the present value of the future estimated costs. TVA has ascribed probabilities to two different decommissioning methods related to its nuclear decommissioning obligation estimate: the DECON method and the SAFESTOR method. The DECON method requires radioactive contamination to be removed from a site and safely disposed of or decontaminated to a level that permits the site to be released for unrestricted use shortly after it ceases operation. The SAFSTOR method allows nuclear facilities to be placed and maintained in a condition that allows the facilities to be safely stored and subsequently decontaminated to levels that permit release for unrestricted use. TVA bases its nuclear decommissioning estimates on site-specific cost studies. These studies will be updated for each of TVA’s nuclear units at least every 5 years and were most recently performed in 2014. In April 2015, the EPA published its final rule governing coal combustion residuals, which regulates landfill and impoundment location, design, and operations; dictates certain pond-closure conditions; and establishes groundwater monitoring and closure and post-closure standards. As a result of these rules, TVA recorded certain adjustments to its ARO liabilities in 2015. TVA continues to evaluate the impact of the rule on its operations, including cost and timing estimates of related projects. As a result, further adjustments to its ARO liabilities may be required as estimates are refined. During the three months ended December 31, 2015 , both the nuclear and non-nuclear liabilities were increased by periodic accretion, partially offset by settlement projects that were conducted during these periods. The nuclear and non-nuclear accretion amounts were deferred as regulatory assets. During the three months ended December 31, 2015 , $ 36 million of the related regulatory assets were amortized into expense as these amounts were collected in rates. See Note 6 . TVA maintains investment trusts to help fund its decommissioning obligations. See Note 13 and Note 16 — 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, 2015 $ 2,187 $ 1,656 $ 3,843 Settlements — (22 ) (22 ) Change in estimate — (7 ) (7 ) Accretion (recorded as regulatory asset) 26 11 37 Balance at December 31, 2015 $ 2,213 $ 1,638 $ 3,851 (1 ) Note (1) The current portion of ARO in the amount of $ 183 million is included in Accounts payable and accrued liabilities at December 31, 2015 .

Debt and Other Obligations

Debt and Other Obligations	3 Months Ended
	Dec. 31, 2015
Debt Disclosure [Abstract]
Debt and Other Obligations	Debt and Other Obligations Debt Outstanding Total debt outstanding at December 31, 2015 , and September 30, 2015 , consisted of the following: Debt Outstanding At December 31, 2015 At September 30, 2015 Short-term debt Short-term debt, net $ 1,504 $ 1,034 Current maturities of long-term debt of variable interest entities 33 33 Current maturities of power bonds 554 32 Total current debt outstanding, net 2,091 1,099 Long-term debt Long-term debt of variable interest entities 1,246 1,246 Long-term power bonds (1) 22,242 22,792 Unamortized discounts, premiums, issue costs, and other (184 ) (188 ) Total long-term debt, net 23,304 23,850 Total outstanding debt $ 25,395 $ 24,949 Note (1) Includes net exchange gain from currency transactions of $ 44 million at December 31, 2015 and $ 21 million at September 30, 2015 . Debt Securities Activity The table below summarizes the long-term debt securities activity for the period from October 1, 2015, to December 31, 2015 : Debt Securities Activity Date Amount Interest Rate Redemptions/Maturities electronotes ® First Quarter 2016 $ 1 2.65 % 2009 Series A November 2015 2 2.25 % 2009 Series B December 2015 1 3.77 % Total redemptions/maturities of power bonds 4 Total redemptions/maturities of debt $ 4 Note (1) All redemptions were at 100 percent of par. Credit Facility Agreements 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 2016 with a maturity date of September 30, 2016. 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 United States with maturities from date of issue of one year or less. There were no outstanding borrowings under the facility at December 31, 2015 . The availability of this credit facility may be impacted by how the U.S. government addresses the situation of approaching its debt limit. TVA also has funding available in the form of three long-term revolving credit facilities totaling $ 2.5 billion . The $ 500 million credit facility matures on February 1, 2020, one $ 1.0 billion credit facility matures on June 2, 2020, and another $ 1.0 billion credit facility matures on September 30, 2020. 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 $ 2.5 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 both December 31, 2015 and September 30, 2015 , there were $ 1.1 billion of letters of credit outstanding under the facilities, and there were no borrowings outstanding. See Note 12 — Other Derivative Instruments — Collateral . The following table provides additional information regarding TVA's funding available in the form of three long-term credit facilities: Summary of Long-Term Credit Facilities At December 31, 2015 (in billions) Maturity Date Facility Limit Letters of Credit Outstanding Cash Borrowings Availability February 2020 $ 0.5 $ 0.5 $ — $ — June 2020 1.0 0.3 — 0.7 September 2020 1.0 0.3 — 0.7 Total $ 2.5 $ 1.1 $ — $ 1.4 Lease/Leaseback Obligations Prior to 2004, TVA received approximately $ 945 million in proceeds by entering into lease/leaseback transactions for 24 new peaking combustion turbine units. TVA also received approximately $ 389 million in proceeds by entering into lease/leaseback transactions for qualified technological equipment and software in 2003. Due to TVA's continuing involvement in the operation and maintenance of the leased units and equipment and its control over the distribution of power produced by the combustion turbine facilities during the leaseback term, TVA accounted for the lease proceeds as financing obligations. At both December 31, 2015 , and September 30, 2015 , the outstanding lease/leaseback obligations were $ 616 million .

Accumulated Other Comprehensive

Accumulated Other Comprehensive Income (Loss)	3 Months Ended
	Dec. 31, 2015
Equity [Abstract]
Accumulated Other Comprehensive Income (Loss)	Accumulated Other Comprehensive Income (Loss) Accumulated other comprehensive income (loss) ("AOCI") represents market valuation adjustments related to TVA’s currency swaps. The currency swaps are cash flow hedges and are the only derivatives in TVA’s portfolio that have been designated and qualify for hedge accounting treatment. TVA records exchange rate gains and losses on its foreign currency-denominated debt in net income and marks its currency swap assets and liabilities to market through other comprehensive income (loss) ("OCI") . TVA then reclassifies an amount out of AOCI into net income, offsetting the exchange gain/loss recorded on the debt. During the three months ended December 31, 2015 and 2014 , TVA reclassified $24 million and $38 million of losses, respectively, related to its cash flow hedges from AOCI to Interest expense. 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 AOCI or that would impact the statements of operations are recorded as regulatory assets or regulatory liabilities. See Note 6 for a schedule of regulatory assets and liabilities. See Note 12 for a discussion of the recognition in AOCI of gains and losses associated with certain derivative contracts. See Note 13 for a discussion of the recognition of certain investment fund gains and losses as regulatory assets and liabilities. See Note 15 for a discussion of the regulatory accounting related to components of TVA’s benefit plans.

Risk Management Activities and

Risk Management Activities and Derivative Transactions	3 Months Ended
	Dec. 31, 2015
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. These include 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 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 policy to enter into these derivative transactions solely for hedging purposes and not for speculative purposes. TVA plans to continue to manage fuel price volatility through various methods, but is currently evaluating the future use of financial instruments. 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 OCI Three Months Ended Derivatives in Cash Flow Hedging Relationship Objective of Hedge Transaction Accounting for Derivative Hedging Instrument 2015 2014 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 $ (27 ) $ (15 ) Summary of Derivative Instruments That Receive Hedge Accounting Treatment (part 2) Amount of Gain (Loss) Reclassified from OCI to Interest Expense Three Months Ended Derivatives in Cash Flow Hedging Relationship 2015 2014 Currency swaps $ (24 ) $ (38 ) Note There were no ineffective portions or amounts excluded from effectiveness testing for any of the periods presented. Based on forecasted foreign currency exchange rates, TVA expects to reclassify approximately $ 44 million of losses from AOCI to interest expense within the next twelve months to offset amounts anticipated to be recorded in interest expense related to exchange gain on the debt. Summary of Derivative Instruments That Do Not Receive Hedge Accounting Treatment Amount of Gain (Loss) Recognized in Income on Derivatives Three Months Ended December 31 ( 1) Derivative Type Objective of Derivative Accounting for Derivative Instrument 2015 2014 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 assets or liabilities. Realized gains and losses are recognized in interest expense when payments are made or received on the swap settlement dates. $ (28 ) $ (29 ) Commodity contract derivatives To protect against fluctuations in market prices of purchased coal or natural gas (price risk) Mark-to-market gains and losses are recorded as regulatory assets or liabilities. Realized gains and losses due to contract settlements are recognized in fuel expense as incurred. — — Commodity derivatives under financial trading program ("FTP") To protect against fluctuations in market prices of purchased commodities (price risk) Mark-to-market gains and losses are recorded as regulatory assets or liabilities. Realized gains and losses are recognized in fuel expense or purchased power expense when the related commodity is used in production. (36 ) (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 was no related gain (loss) recognized in income for these unrealized gains (losses) for the three months ended December 31, 2015 and 2014 . Fair Values of TVA Derivatives At December 31, 2015 At September 30, 2015 Derivatives That Receive Hedge Accounting Treatment Balance Balance Sheet Presentation Balance Balance Sheet Presentation Currency swaps £200 million Sterling $ (43 ) Other long-term liabilities $ (41 ) Other long-term liabilities £250 million Sterling 9 Other long-term assets 25 Other long-term assets £150 million Sterling (15 ) Other long-term liabilities (6 ) Other long-term liabilities At December 31, 2015 At September 30, 2015 Derivatives That Do Not Receive Hedge Accounting Treatment Balance Balance Sheet Presentation Balance Balance Sheet Presentation Interest rate swaps $1.0 billion notional (1,115 ) Other long-term liabilities (1,177 ) Other long-term liabilities $476 million notional (412 ) Other long-term liabilities (438 ) Other long-term liabilities $42 million notional (11 ) Other long-term liabilities (12 ) Other long-term liabilities Commodity contract derivatives (138 ) Other long-term assets $4; Other long-term liabilities $(46); Accounts payable and accrued liabilities $(96) (97 ) Other long-term assets $1; Other long-term liabilities $(17); Accounts payable and accrued liabilities $(81) FTP Derivatives under FTP (1) (101 ) Other current assets $(80); Other long-term liabilities $(9); Accounts payable and accrued liabilities $(12) (116 ) Other current assets $(89); Other long-term liabilities $(10); Accounts payable and accrued liabilities $(17) Note (1) Fair values of certain derivatives under the FTP that were in net liability positions totaling $80 million and $ 89 million at December 31, 2015 and September 30, 2015 , respectively, are recorded in TVA's margin cash accounts in Other current assets. These derivatives are transacted with futures commission merchants, and cash deposits have been posted to the margin cash accounts held with each futures commission merchant to offset the net liability positions in full. Cash Flow Hedging Strategy for Currency Swaps To protect against exchange rate risk related to three British pound sterling denominated Bond transactions, TVA entered into foreign currency hedges at the time the Bond transactions occurred. TVA had the following currency swaps outstanding as of December 31, 2015 : Currency Swaps Outstanding At December 31, 2015 Effective Date of Currency Swap Contract Associated TVA Bond Issues Currency Exposure Expiration Date of Swap Overall Effective Cost to TVA 1999 £200 million 2021 5.81% 2001 £250 million 2032 6.59% 2003 £150 million 2043 4.96% When the dollar strengthens against the British pound sterling, the exchange gain on the Bond liability is offset by an exchange loss on the swap contract. Conversely, when the dollar weakens against the British pound sterling, the exchange loss on the Bond liability is offset by an exchange gain on the swap contract. All such exchange gains or losses on the Bond liability are included in Long-term debt, net. 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. Derivatives Not Receiving Hedge Accounting Treatment Interest Rate Derivatives . 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 assets or liabilities on TVA's consolidated balance sheets and are included in the ratemaking formula when the transactions settle. The values of these derivatives are included in Other long-term assets or Other long-term liabilities on the consolidated balance sheets, and realized gains and losses, if any, are included in TVA's consolidated statements of operations. For the three months ended December 31, 2015 and 2014 , the changes in fair market value of the interest rate swaps resulted in deferred unrealized gains (losses) of $ 89 million and $ (184) million , respectively. Commodity Derivatives . TVA enters into certain derivative contracts for coal and natural gas that require physical delivery of the contracted quantity of the commodity. TVA marks to market all such contracts and defers the fair market values as regulatory assets or liabilities on a gross basis. At December 31, 2015 , TVA's coal and natural gas contract derivatives both had terms of up to 3 years . Commodity Contract Derivatives At December 31, 2015 At September 30, 2015 Number of Contracts Notional Amount Fair Value (MtM) Number of Contracts Notional Amount Fair Value ( MtM ) Coal contract derivatives 12 20 million tons $ (123 ) 14 19 million tons $ (98 ) Natural gas contract derivatives 30 132 million mmBtu $ (15 ) 33 134 million mmBtu $ 1 Derivatives Under FTP. While TVA is currently evaluating the use of financial instruments for price hedging, certain natural gas swaps with a maturity of two years or less remain as part of the suspended FTP. The FTP is designed to allow TVA to purchase and sell futures, swaps, options, and combinations of these instruments (as long as they are standard in the industry) to hedge TVA’s exposure to (1) the price of natural gas, fuel oil, electricity, coal, emission allowances, nuclear fuel, and other commodities included in TVA’s fuel cost adjustment calculation, (2) the price of construction materials, and (3) contracts for goods priced in or indexed to foreign currencies. The combined transaction limit for the fuel cost adjustment and construction material transactions is $ 130 million (based on one-day value at risk). In addition, the maximum hedge volume for the construction material transactions is 75 percent of the underlying net notional volume of the material that TVA anticipates using in approved TVA projects, and the market value of all outstanding hedging transactions involving construction materials is limited to $ 100 million at the execution of any new transaction. The portfolio value at risk limit for the foreign currency transactions is $ 5 million and is separate and distinct from the $ 130 million transaction limit discussed above. TVA's policy prohibits trading financial instruments under the FTP for speculative purposes. Derivatives Under Financial Trading Program At December 31, 2015 At September 30, 2015 Notional Amount Fair Value (MtM) (in millions) Notional Amount Fair Value (MtM) (in millions) Natural gas (in mmBtu) Swap contracts 40,977,500 $ (101 ) 51,495,000 $ (116 ) Note Fair value amounts presented are based on the net commodity position with the counterparty. Notional amounts disclosed represent the net absolute value of contractual amounts. TVA defers all FTP unrealized gains (losses) as regulatory liabilities (assets) and records only realized gains or losses to match the delivery period of the underlying commodity. In addition to the open commodity derivatives disclosed above, TVA had closed derivative contracts with market values of $ (6) million at December 31, 2015 , and $ (11) million at September 30, 2015 . TVA experienced the following unrealized and realized gains and losses related to the FTP at the dates and during the periods, as applicable, set forth in the tables below: Financial Trading Program Unrealized Gains (Losses) At December 31, 2015 At September 30, 2015 FTP unrealized gains (losses) deferred as regulatory liabilities (assets) Natural gas $ (101 ) $ (116 ) Financial Trading Program Realized Gains (Losses) For the Three Months Ended 2015 2014 Decrease (increase) in fuel expense Natural gas $ (29 ) $ (12 ) Fuel oil/crude oil — 1 Financial Trading Program Realized Gains (Losses) For the Three Months Ended 2015 2014 Decrease (increase) in purchased power expense Natural gas $ (7 ) $ (3 ) Offsetting of Derivative Assets and Liabilities The amounts of TVA's derivative instruments as reported in the Consolidated Balance Sheets as of December 31, 2015 , and September 30, 2015 , are shown in the table below: Derivative Assets and Liabilities As of December 31, 2015 Gross Amounts of Recognized Assets/Liabilities Gross Amounts Offset in the Balance Sheet (1) Net Amounts of Assets/Liabilities Presented in the Balance Sheet (2) Assets Currency swap(s) (3)(4) $ 9 $ — $ 9 Commodity derivatives under FTP 36 (36 ) — Total derivatives subject to master netting or similar arrangement 45 (36 ) 9 Total derivatives not subject to master netting or similar arrangement 4 — 4 Total $ 49 $ (36 ) $ 13 Liabilities Currency swap(s) (4) $ 58 $ — $ 58 Interest rate swaps (4) 1,538 — 1,538 Commodity derivatives under FTP 137 (116 ) 21 Total derivatives subject to master netting or similar arrangement 1,733 (116 ) 1,617 Total derivatives not subject to master netting or similar arrangement 142 — 142 Total $ 1,875 $ (116 ) $ 1,759 As of September 30, 2015 Gross Amounts of Recognized Assets/Liabilities Gross Amounts Offset in the Balance Sheet (1) Net Amounts of Assets/Liabilities Presented in the Balance Sheet (2) Assets Currency swap(s) (3)(4) $ 25 $ — $ 25 Commodity derivatives under FTP 49 (49 ) — Total derivatives subject to master netting or similar arrangement 74 (49 ) 25 Total derivatives not subject to master netting or similar arrangement 1 — 1 Total $ 75 $ (49 ) $ 26 Liabilities Currency swap(s) (4) $ 47 $ — $ 47 Interest rate swaps (4) 1,627 — 1,627 Commodity derivatives under FTP 165 (138 ) 27 Total derivatives subject to master netting or similar arrangement 1,839 (138 ) 1,701 Total derivatives not subject to master netting or similar arrangement 98 — 98 Total $ 1,937 $ (138 ) $ 1,799 Notes (1) Amounts primarily include counterparty netting of derivative contracts, margin account deposits for futures commission merchants transactions, and cash collateral received or paid in accordance with the accounting guidance for derivatives and hedging transactions. (2) There are no derivative contracts subject to a master netting arrangement or similar agreement which are not offset in the balance sheets. (3) At December 31, 2015 and September 30, 2015 , there were no securities posted by a counterparty on TVA's behalf to partially secure the asset position(s) of currency swaps in accordance with the collateral requirements for these derivatives. (4) Letters of credit of approximately $ 1.1 billion were posted as collateral at both December 31, 2015 and September 30, 2015 , to partially secure the liability positions of one of the currency swaps and one of the interest rate swaps in accordance with the collateral requirements for these derivatives. TVA held $ 20 million and $15 million cash collateral in excess of collateral requirements at December 31, 2015 and September 30, 2015 , respectively. Cash collateral held in excess of collateral requirements is recorded in Restricted cash and investments with a corresponding obligation of the same amount recorded in Accounts payable and accrued liabilities. 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 Long-Term Deferred Compensation Plan ("LTDCP") . All securities in the trusts are classified as trading. See Note 13 — Investment Funds for a discussion of the trusts' objectives and the types of investments included in the various trusts. These trusts may invest in derivative instruments which may include swaps, futures, options, forwards, and other instruments. At December 31, 2015 and September 30, 2015 , the NDT held investments in forward contracts to purchase debt securities. The fair values of these derivatives were in net liability positions totaling $8 million and $ 59 million at December 31, 2015 and September 30, 2015 , respectively. At December 31, 2015 and September 30, 2015 , the fair value of other derivative instruments in these trusts was not material to TVA's consolidated financial statements. Collateral . TVA's interest rate swaps and currency swaps 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 December 31, 2015 , the aggregate fair value of all derivative instruments with credit-risk related contingent features that were in a liability position was $ 1.6 billion . TVA's collateral obligations at December 31, 2015 , under these arrangements were approximately $ 1.1 billion , for which TVA had posted approximately $ 1.1 billion 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 contract 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 ("S&P") or Moody's Investors Service, Inc. ("Moody's") downgrades TVA's credit rating to AA or Aa2, respectively, TVA's collateral obligations would likely increase by $ 22 million and • If TVA ceases to be majority-owned by the U.S. government, TVA's credit rating would likely be downgraded and TVA would be required to post additional collateral. Counterparty Credit Risk Credit risk is the exposure to economic loss that would occur as a result of a counterparty's nonperformance of its contractual obligations. Where exposed to counterparty credit 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 employs credit mitigation measures, such as collateral or prepayment arrangements and master purchase and sale agreements, to mitigate credit risk. Credit of Customers . The majority of TVA's counterparty credit risk is associated with trade accounts receivable from delivered power sales to LPCs, all located in the Tennessee Valley region. To a lesser extent, TVA is exposed to credit risk from industries and federal agencies directly served and 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 had concentrations of revenue from six LPCs that accounted for 32 percent of total operating revenue for both the three months ended December 31, 2015 and the three months ended December 31, 2014 . Credit of Derivative Counterparties . TVA has entered into physical and financial contracts that qualify as derivatives for hedging purposes, and TVA's NDT fund and qualified defined benefit pension plan have entered into derivative contracts for investment purposes. If a counterparty to one of TVA's hedging transactions defaults, TVA might incur substantial costs in connection with entering into a replacement hedging transaction. If a counterparty to the derivative contracts into which the NDT fund and the pension plan have entered for investment purposes defaults, the value of the investment could decline significantly or perhaps become worthless. TVA has concentrations of credit risk from the banking and coal industries because multiple companies in these industries serve as counterparties to TVA in various derivative transactions. At December 31, 2015 , all of TVA's currency swaps, interest rate swaps, and commodity derivatives under the FTP were with banking counterparties whose Moody's credit rating was Baa1 or higher. TVA classifies qualifying forward coal contracts as derivatives. At December 31, 2015 , these contracts were with suppliers whose Moody's credit rating, or TVA’s internal analysis when such information was unavailable, ranged from Ca to Baa3 . Emerging technologies, environmental regulations, and low gas prices have contributed to weak demand for coal. As a result, coal suppliers are facing increased financial pressure which has led to relatively poor credit ratings and bankruptcies. Continued difficulties by coal suppliers could result in consolidations, additional bankruptcies, restructuring, contract renegotiations, or other scenarios. Under these scenarios and TVA’s potential available responses, TVA does not anticipate a significant financial impact in obtaining continued fuel supply for its coal-fired generation. TVA does not have any derivative contracts with coal counterparties in an asset position as of December 31, 2015. See Derivatives Not Receiving Hedge Accounting Treatment above. TVA currently utilizes two futures commission merchants ("FCMs") to clear commodity contracts, including futures, options, and similar financial derivatives. These transactions are executed under the FTP by the FCMs on exchanges on behalf of TVA. TVA maintains margin cash accounts with the FCMs. TVA makes deposits to the margin cash accounts to adequately cover any net liability positions on its derivatives transacted with the FCMs. See the note to the Fair Values of TVA Derivatives table above. Credit of Suppliers . If one of TVA's fuel or purchased power suppliers fails to perform under the terms of its 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. To help ensure a reliable supply of coal, TVA had coal contracts with multiple suppliers at December 31, 2015 . The contracted supply of coal is sourced from multiple geographic regions of the United States and is to be delivered via various transportation methods (for example, barge, rail, and truck). Nuclear fuel requirements including uranium mining and milling, conversion services, enrichment services, and fabrication services are met from various suppliers, depending on type of service. TVA purchases the majority of its natural gas requirements from a variety of suppliers under short-term contracts. TVA has a power purchase agreement that expires on March 31, 2032, with a supplier of electricity for 440 megawatts ("MW") of summer net capability from a lignite-fired generating plant. TVA has determined that the supplier has the equivalent of a non-investment grade credit rating; therefore, the supplier has provided credit assurance to TVA under the terms of the agreement.

Fair Value Measurements

Fair Value Measurements	3 Months Ended
	Dec. 31, 2015
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 3 is the lowest and Level 1 is the highest) 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 LTDCP 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 LTDCP 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 December 31, 2015 , Investment funds were composed of $ 2.1 billion of securities classified as trading and measured at fair value and less than $ 1 million of equity investments not required to be measured at fair value. Trading securities are held in the NDT, ART, SERP, and LTDCP. 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 $ 1.5 billion and $ 449 million , respectively, at December 31, 2015 . TVA established a SERP for certain executives in critical positions to provide supplemental pension benefits tied to compensation that exceeds limits set by Internal Revenue Service rules applicable to the qualified defined benefit pension plan. The LTDCP is designed to provide long-term incentives to executives to encourage them to stay with TVA and to provide competitive levels of total compensation to such executives. The NDT and SERP are invested in securities generally designed to achieve a return in line with overall equity market performance, and the ART and LTDCP are invested in securities generally designed to achieve a return in line with overall debt and equity market performance. The NDT, ART, SERP, and LTDCP are composed of multiple types of investments and are managed by external institutional managers. Most U.S. and international equities, 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 partnership 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. Investments in private partnerships generally involve a three-to-four-year period where the investor contributes capital. This is followed by a period of distribution, typically over several years. The investment period is generally, at a minimum, ten years or longer. The NDT had unfunded commitments related to private partnerships of $ 79 million at December 31, 2015 . These investments have no redemption or limited redemption options and may also have imposed restrictions on the NDT’s ability to liquidate its investment. There are no readily available quoted exchange prices for these investments. The fair value of the investments is based on TVA’s ownership percentage of the fair value of the underlying investments as provided by the investment managers. These investments are typically valued on a quarterly basis. TVA’s private partnership 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 net asset value 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 LTDCP 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 investments measured at net asset value in the fair value hierarchy. Realized and unrealized gains and losses on trading 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 — Cost-Based Regulation . TVA recorded unrealized gains and losses related to its trading securities held as of the end of each period as follows: Unrealized Investment Gains (Losses) For the Three Months Ended Financial Statement Presentation 2015 2014 SERP Other income (expense) $ — $ (1 ) LTDCP Other income (expense) — (1 ) NDT Regulatory asset 39 23 ART Regulatory asset 12 6 Currency and Interest Rate Swaps See Note 12 — 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 FTP Commodity Contract Derivatives. Most of these contracts are valued based on market approaches which utilize short- and mid-term market-quoted prices from an external industry brokerage service. A small number of these contracts are valued based on a pricing model using long-term price estimates from TVA's coal price forecast. To value the volume option component of applicable coal contracts, TVA uses a Black-Scholes pricing model which includes inputs from the forecast, contract-specific terms, and other market inputs. These contracts are classified as Level 3 valuations. Commodity Derivatives Under FTP. These contracts are valued based on market approaches which utilize Chicago Mercantile Exchange ("CME") quoted prices and other observable inputs. Futures and options contracts settled on the CME are classified as Level 1 valuations. Swap contracts are valued using a pricing model based on CME inputs and are subject to nonperformance risk outside of the exit price. These contracts are classified as Level 2 valuations. See Note 12 — Derivatives Not Receiving Hedge Accounting Treatment — Commodity Derivatives and — Derivatives Under FTP for a discussion of the nature and purpose of coal contracts and derivatives under TVA's FTP. Nonperformance Risk The assessment of nonperformance risk, which includes credit risk, considers changes in current market conditions, readily available information on nonperformance risk, letters of credit, collateral, other arrangements available, and the nature of master netting arrangements. TVA is a counterparty to currency swaps, interest rate swaps, commodity contracts, and other derivatives which subject TVA to nonperformance risk. Nonperformance risk on the majority of investments and certain exchange-traded instruments held by TVA is incorporated into the exit price that is derived from quoted market data that is used to mark the investment to market. Nonperformance risk for most of TVA's derivative instruments is an adjustment to the initial asset/liability fair value. TVA adjusts for nonperformance risk, both of TVA (for liabilities) and the counterparty (for assets), by applying credit valuation adjustments ("CVAs") . TVA determines an appropriate CVA for each applicable financial instrument based on the term of the instrument and TVA's or the counterparty's credit rating as obtained from Moody's. For companies that do not have an observable credit rating, TVA uses internal analysis to assign a comparable rating to the company. TVA discounts each financial instrument using the historical default rate (as reported by Moody's for CY 1983 to CY 2015) 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 December 31, 2015 . 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 as of December 31, 2015 , and September 30, 2015 . Financial assets and liabilities have been classified in their entirety based on the lowest level of input that is significant to the fair value measurement. TVA's assessment of the significance of a particular input to the fair value measurement requires judgment and may affect the determination of the fair value of the assets and liabilities and their classification in the fair value hierarchy levels. Fair Value Measurements At December 31, 2015 Assets Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total Investments Equity securities $ 185 $ — $ — $ 185 Debt securities U.S. government corporations and agencies 200 39 — 239 Corporate debt securities — 254 — 254 Residential mortgage-backed securities — 16 — 16 Commercial mortgage-backed securities — 5 — 5 Collateralized debt obligations — 28 — 28 Institutional mutual funds 88 — — 88 Forward debt securities contracts — (8 ) — (8 ) Private partnerships measured at net asset value (1) — — — 245 Commingled funds measured at net asset value (1) — — — 1,031 Total investments 473 334 — 2,083 Currency swap(s) (2) — 9 — 9 Commodity contract derivatives — 4 — 4 Commodity derivatives under FTP (2) Swap contracts — — — — Total $ 473 $ 347 $ — $ 2,096 Liabilities Quoted Prices in Active Markets for Identical Liabilities (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total Currency swap(s) (2) $ — $ 58 $ — $ 58 Interest rate swaps — 1,538 — 1,538 Commodity contract derivatives — 19 123 142 Commodity derivatives under FTP (2) Swap contracts — 21 — 21 Total $ — $ 1,636 $ 123 $ 1,759 Notes (1) Certain investments that are measured at fair value using the net asset value 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 in the consolidated balance sheets. (2) Due to the right of setoff and method of settlement, TVA elects to record commodity derivatives under the FTP based on its net commodity position with the counterparty or FCM. Deposits are made to TVA's margin cash accounts held with each FCM to offset any net liability positions in full for derivatives that are transacted with FCMs. TVA records currency swaps net of cash collateral received from or paid to the counterparty, to the extent such amount is not recorded in Accounts payable and accrued liabilities. See Note 12 — Offsetting of Derivative Assets and Liabilities . Fair Value Measurements At September 30, 2015 Assets Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total Investments Equity securities $ 166 $ — $ — $ 166 Debt securities U.S. government corporations and agencies 203 31 — 234 Corporate debt securities — 225 — 225 Residential mortgage-backed securities — 17 — 17 Commercial mortgage-backed securities — 7 — 7 Collateralized debt obligations — 29 — 29 Institutional mutual funds 91 — — 91 Forward debt securities contracts — (59 ) — (59 ) Private partnerships measured at net asset value (1) — — — 240 Commingled funds measured at net asset value (1) — — — 1,061 Total investments 460 250 — 2,011 Currency swap(s) (2) — 25 — 25 Commodity contract derivatives — 1 — 1 Commodity derivatives under FTP (2) Swap contracts — — — — Total $ 460 $ 276 $ — $ 2,037 Liabilities Quoted Prices in Active Markets for Identical Liabilities (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total Currency swap(s) (2) $ — $ 47 $ — $ 47 Interest rate swaps — 1,627 — 1,627 Commodity contract derivatives — — 98 98 Commodity derivatives under FTP (2) Swap contracts — 27 — 27 Total $ — $ 1,701 $ 98 $ 1,799 Notes (1) Certain investments that are measured at fair value using the net asset value 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 in the consolidated balance sheets. (2) Due to the right of setoff and method of settlement, TVA elects to record commodity derivatives under the FTP based on its net commodity position with the counterparty or FCM. Deposits are made to TVA's margin cash accounts held with each FCM to offset any net liability positions in full for derivatives that are transacted with FCMs. TVA records currency swaps net of cash collateral received from or paid to the counterparty, to the extent such amount is not recorded in Accounts payable and accrued liabilities. See Note 12 — Offsetting of Derivative Assets and Liabilities . TVA uses internal valuation specialists for the calculation of its commodity contract derivatives fair value measurements classified as Level 3. Analytical testing is performed on the change in fair value measurements each period to ensure the valuation is reasonable based on changes in general market assumptions. Significant changes to the estimated data used for unobservable inputs, in isolation or combination, may result in significant variations to the fair value measurement reported. The following table presents a reconciliation of all commodity contract derivatives measured at fair value on a recurring basis using significant unobservable inputs (Level 3): Fair Value Measurements Using Significant Unobservable Inputs Commodity Contract Derivatives Balance At September 30, 2014 $ (85 ) Purchases — Issuances — Sales — Settlements — Net unrealized gains (losses) deferred as regulatory assets and liabilities (22 ) Balance at December 31, 2014 $ (107 ) Balance at September 30, 2015 $ (98 ) Purchases — Issuances — Sales — Settlements — Net unrealized gains (losses) deferred as regulatory assets and liabilities (25 ) Balance at December 31, 2015 $ (123 ) The following table presents quantitative information related to the significant unobservable inputs used in the measurement of fair value of TVA's assets and liabilities classified as Level 3 in the fair value hierarchy: Quantitative Information about Level 3 Fair Value Measurements Fair Value at December 31 2015 Valuation Technique(s) Unobservable Inputs Range Assets Commodity contract derivatives $ — Pricing model Coal supply and demand 0.8 - 1.0 billion tons/year Long-term market prices $9.83 - $121.51/ton Liabilities Commodity contract derivatives $ 123 Pricing model Coal supply and demand 0.8 - 1.0 billion tons/year Long-term market prices $9.83 - $121.51/ton Quantitative Information about Level 3 Fair Value Measurements Fair Value at September 30 2015 Valuation Technique(s) Unobservable Inputs Range Assets Commodity contract derivatives $ — Pricing model Coal supply and demand 0.8 - 1.0 billion tons/year Long-term market prices $10.64 - $103.41/ton Liabilities Commodity contract derivatives $ 98 Pricing model Coal supply and demand 0.8 - 1.0 billion tons/year Long-term market prices $10.64 - $103.41/ton 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 instrument. The fair values of the financial instruments held at December 31, 2015 , and September 30, 2015 , 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 fair values of TVA's financial instruments not recorded at fair value at December 31, 2015 , and September 30, 2015 , were as follows: Estimated Values of Financial Instruments Not Recorded at Fair Value At December 31, 2015 At September 30, 2015 Valuation Classification Carrying Amount Fair Value Carrying Amount Fair Value EnergyRight ® receivables (including current portion) Level 2 $ 155 $ 161 $ 156 $ 162 Loans and other long-term receivables, net (including current portion) Level 2 $ 135 $ 124 $ 129 $ 117 EnergyRight ® financing obligation (including current portion) Level 2 $ 183 $ 205 $ 185 $ 208 Unfunded loan commitments Level 2 $ — $ 11 $ — $ 9 Membership interest of variable interest entity subject to mandatory redemption (including current portion) Level 2 $ 37 $ 46 $ 37 $ 47 Long-term outstanding power bonds (including current maturities), net Level 2 $ 22,625 $ 26,155 $ 22,649 $ 25,468 Long-term debt of variable interest entities (including current maturities), net Level 2 $ 1,266 $ 1,388 $ 1,266 $ 1,407 Due to the short-term maturity of Cash and cash equivalents, Restricted cash and investments, and Short-term debt, net (each considered a Level 1 valuation classification), the carrying amounts of these instruments 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 traded in the public market is determined by multiplying the par value of the debt by the indicative market price at the balance sheet date. The fair value of other long-term debt and membership interests of variable interest entity 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	3 Months Ended
	Dec. 31, 2015
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 For the Three Months Ended 2015 2014 Interest income $ 6 $ 6 External services 4 3 Gains (losses) on investments 3 1 Miscellaneous (1 ) (1 ) Total other income (expense), net $ 12 $ 9

Benefit Plans

Benefit Plans	3 Months Ended
	Dec. 31, 2015
Compensation and Retirement Disclosure [Abstract]
Benefit Plans	Benefit Plans TVA sponsors a qualified defined benefit pension plan (the "Plan") that covers most of its full-time employees hired before July 1, 2014, a qualified defined contribution 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 postemployment benefits, such as workers' compensation, and the SERP. The components of net periodic benefit cost and other amounts recognized as changes in regulatory assets for the three months ended December 31, 2015 , and 2014 , were as follows: Components of TVA’s Benefit Plans For the Three Months Ended December 31 Pension Benefits Other Post-Retirement Benefits 2015 2014 2015 2014 Service cost $ 32 $ 34 $ 4 $ 5 Interest cost 140 133 7 8 Expected return on plan assets (111 ) (109 ) — — Amortization of prior service credit (6 ) (5 ) (1 ) (2 ) Recognized net actuarial loss 73 69 2 2 Total net periodic benefit cost as actuarially determined 128 122 12 13 Amount capitalized due to actions of regulator (58 ) (51 ) — — Total net periodic benefit cost $ 70 $ 71 $ 12 $ 13 TVA contributes to the Plan such amounts as are necessary on an actuarial basis to provide the Plan with assets sufficient to meet TVA-funded benefit obligations to be paid to members. TVA contributed $ 275 million to the Plan in 2015 and expects to contribute the same amount in 2016. TVA does not separately set aside assets to fund other benefit costs, but rather funds such costs on an as-paid basis. TVA provided approximately $ 17 million and $ 16 million , net of rebates and subsidies, to other post-retirement benefit plans for the three months ended December 31, 2015 , and 2014 , respectively. TVA includes its cash contributions to the pension plan in the rate-making formula; accordingly, TVA recognizes pension costs as regulatory assets to the extent that the amount calculated under GAAP as pension expense differs from the amount TVA contributes to the pension plan.

Contingencies and Legal Proceed

Contingencies and Legal Proceedings	3 Months Ended
	Dec. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Contingencies and Legal Proceedings	Contingencies and Legal Proceedings Contingencies Nuclear Insurance . The Price-Anderson Act provides a layered framework of protection to compensate for losses arising from a nuclear event in the United States. For the first layer, all of the NRC nuclear plant licensees, including TVA, purchase $ 375 million of nuclear liability insurance from American Nuclear Insurers for each plant with an operating license. Funds for the second layer, the Secondary Financial Program, would come from an assessment of up to $ 127 million from the licensees of each of the 103 NRC licensed reactors in the United States. The assessment for any nuclear accident would be limited to $ 19 million per year per unit. American Nuclear Insurers, under a contract with the NRC, administers the Secondary Financial Program. With its seven licensed units, TVA could be required to pay a maximum of $ 891 million per nuclear incident, but it would have to pay no more than $ 133 million per incident in any one year. When the contributions of the nuclear plant licensees are added to the insurance proceeds of $ 375 million , over $ 13.0 billion , including a five percent surcharge for legal expenses, would be available. Under the Price-Anderson Act, if the first two layers are exhausted, the U.S. Congress is required to take action to provide additional funds to cover the additional losses. TVA carries property, decommissioning, and decontamination insurance of $ 5.1 billion for its licensed nuclear plants, with up to $ 2.1 billion available for a loss at any one site, to cover the cost of stabilizing or shutting down a reactor after an accident. Some of this insurance, which is purchased from Nuclear Electric Insurance Limited ("NEIL") , may require the payment of retrospective premiums up to a maximum of approximately $ 127 million . TVA purchases accidental outage (business interruption) insurance for TVA’s nuclear sites from NEIL. In the event that an accident covered by this policy takes a nuclear unit offline or keeps a nuclear unit offline, NEIL will pay TVA, after a waiting period, an indemnity (a set dollar amount per week) up to a maximum indemnity of $ 490 million per unit. This insurance policy may require the payment of retrospective premiums up to a maximum of approximately $ 36 million . Decommissioning Costs. TVA recognizes legal obligations associated with the future retirement of certain tangible long-lived assets related primarily to coal-fired generating plants and nuclear generating plants, hydroelectric generating plants/dams, transmission structures, and other property-related assets. See Note 9 . Nuclear Decommissioning . Provision for decommissioning costs of nuclear generating units is based on options prescribed by the NRC procedures to dismantle and decontaminate the facilities to meet the NRC criteria for license termination. At December 31, 2015 , the present value of the estimated future decommissioning cost of $ 2.2 billion was included in AROs. The actual decommissioning costs may vary from the derived estimates because of, among other things, changes in current assumptions, such as the assumed dates of decommissioning, changes in regulatory requirements, changes in technology, and changes in the cost of labor, materials, and equipment. Utilities that own and operate nuclear plants are required to use different procedures in calculating nuclear decommissioning costs under GAAP than those that are used in calculating nuclear decommissioning costs when reporting to the NRC. The two sets of procedures produce different estimates for the costs of decommissioning primarily because of the difference in the discount rates used to calculate the present value of decommissioning costs. TVA maintains a NDT to provide funding for the ultimate decommissioning of its nuclear power plants. See Note 13 . TVA monitors the value of its NDT and believes that, over the long term and before cessation of nuclear plant operations and commencement of decommissioning activities, adequate funds from investments will be available to support decommissioning. TVA’s operating nuclear power units are licensed through 2033 - 2055, depending on the unit. It may be possible to extend the operating life of some of the units with approval from the NRC. Non-Nuclear Decommissioning . The present value of the estimated future non-nuclear decommissioning ARO was $ 1.6 billion at December 31, 2015 . This decommissioning cost estimate involves estimating the amount and timing of future expenditures and making judgments concerning whether or not such costs are considered a legal obligation. Estimating the amount and timing of future expenditures includes, among other things, making projections of the timing and duration of the asset retirement process and how costs will escalate with inflation. The actual decommissioning costs may vary from the derived estimates because of changes in current assumptions, such as the assumed dates of decommissioning, changes in regulatory requirements, changes in technology, and changes in the cost of labor, materials, and equipment. TVA maintains an ART to help fund the ultimate decommissioning of its power assets. See Note 13 . Estimates involved in determining if additional funding will be made to the ART include inflation rate and rate of return projections on the fund investments. Environmental Matters. TVA’s power generation activities, like those across the utility industry and in other industrial sectors, are subject to most federal, state, and local environmental laws and regulations. Major areas of regulation affecting TVA’s activities include air quality control, water quality control, and management and disposal of solid and hazardous wastes. In the future, regulations in all of these areas are expected to become more stringent. Regulations are also expected to apply to new emissions and sources, with a particular emphasis on climate change, renewable generation, and energy efficiency. TVA has incurred, and expects to continue to incur, substantial capital and operating and maintenance costs to comply with evolving environmental requirements primarily associated with, but not limited to, the operation of TVA’s coal-fired generating units. It is virtually certain that environmental requirements placed on the operation of TVA’s coal-fired and other generating units will continue to become more restrictive and potentially apply to new emissions and sources. Litigation over emissions or discharges from coal-fired generating units is also occurring, including litigation against TVA. Failure to comply with environmental and safety laws can result in TVA being subject to enforcement actions, which can lead to the imposition of significant civil liability, including fines and penalties, criminal sanctions, and/or the shutting down of non-compliant facilities . TVA estimates that compliance with future Clean Air Act ("CAA") requirements (excluding greenhouse gas ("GHG") requirements) could lead to additional costs of $650 million from 2016 to 2025 for additional clean air controls. There could be additional material costs if reductions of GHGs, including carbon dioxide ("CO 2 "), are mandated under the CAA or by legislation or regulation, or if future legislative, regulatory, or judicial actions lead to more stringent emission reduction requirements for conventional pollutants. These costs cannot reasonably be predicted at this time because of the uncertainty of such potential actions. Liability for releases and cleanup of hazardous substances is primarily regulated by the federal Comprehensive Environmental Response, Compensation, and Liability Act, and other federal and parallel state statutes. In a manner similar to many other industries and power systems, TVA has generated or used hazardous substances over the years. TVA is aware of alleged hazardous-substance releases at certain non-TVA areas in connection with which other potentially responsible parties may seek monetary damages from TVA. There is information indicating that TVA sent a small amount of equipment to Ward Transformer ("Ward") , a non-TVA site in Raleigh, North Carolina. The site is contaminated by PCBs from electrical equipment due to Ward’s practice of draining such equipment. A working group of potentially responsible parties is cleaning up on-site contamination in accordance with an agreement with the EPA. The cleanup effort has been divided into multiple phases, including on-site and downstream cleanup activities, two phases of soil cleanup, supplemental groundwater remediation, and cleanup of off-site contamination in the downstream drainage basin. TVA settled its potential liability for the on-site removal action for $ 300 thousand and has agreed to pay approximately $ 8 thousand to settle its potential liability in connection with an EPA study of the site. TVA believes that its liability for the remaining cleanup and remediation activities as well as any natural resource damages will be less than $ 1 million . TVA operations at some TVA facilities have resulted in contamination that TVA is addressing. At December 31, 2015 , TVA’s estimated liability for cleanup and similar environmental work for those sites for which sufficient information is available to develop a cost estimate (primarily the TVA sites) was approximately $ 23 million on a non-discounted basis, and was included in Accounts payable and accrued liabilities and Other long-term liabilities on the December 31, 2015 Consolidated Balance Sheet. In November 2015, TDEC informed TVA that it agreed that TVA had complied with all the requirements of the orders issued by TDEC after the December 22, 2008 ash spill at the Kingston Fossil Plant. This closes all TDEC orders related to the ash spill. TVA has requested that the EPA close its CERCLA order related to the spill, but the order currently remains open. Legal Proceedings From time to time, TVA is party to or otherwise involved in lawsuits, claims, proceedings, investigations, and other legal matters ("Legal Proceedings") that have arisen in the ordinary course of conducting TVA's activities, as a result of a catastrophic event or otherwise. General. At December 31, 2015 , TVA had accrued $ 99 million of probable losses with respect to Legal Proceedings. Of the accrued amount, $ 41 million is included in Other long-term liabilities and $ 58 million is included in Accounts payable and accrued liabilities. TVA is currently unable to estimate any amount or any range of amounts of reasonably possible losses, and no assurance can be given that TVA will not be subject to significant additional claims and liabilities. If actual liabilities significantly exceed the estimates made, TVA's results of operations, liquidity, and financial condition could be materially adversely affected. Environmental Agreements . In April 2011, TVA entered into two substantively similar agreements, a Federal Facilities Compliance Agreement with the EPA and a consent decree with Alabama, Kentucky, North Carolina, Tennessee, and three environmental advocacy groups: the Sierra Club, National Parks Conservation Association, and Our Children's Earth Foundation (collectively, the "Environmental Agreements"). They became effective in June 2011. Under the Environmental Agreements, TVA committed to (1) retire on a phased schedule 18 coal-fired units with a combined summer net dependable capability of 2,200 MW, (2) control, convert, or retire additional coal-fired units with a combined summer net dependable capability of 3,500 MW, (3) comply with annual, declining emission caps for sulfur dioxide ("SO 2 ") and nitrogen oxide ("NO x "), (4) invest $ 290 million in certain TVA environmental projects, (5) provide $ 60 million to Alabama, Kentucky, North Carolina, and Tennessee to fund environmental projects, and (6) pay civil penalties of $ 10 million . In exchange for these commitments, most existing and possible claims against TVA based on alleged New Source Review and associated violations were waived and cannot be brought against TVA. Some possible claims for sulfuric acid mist and GHG emissions can still be brought against TVA, and claims for increases in particulates can also be pursued at many of TVA’s coal-fired units. Additionally, the Environmental Agreements do not address compliance with new laws and regulations or the cost associated with such compliance. Case Involving Tennessee Valley Authority Retirement System . In March 2010, eight current and former participants in and beneficiaries of TVARS filed suit in the United States District Court for the Middle District of Tennessee challenging the TVARS Board's 2009 decision to make changes to the TVARS Rules and Regulations (“Rules”) in exchange for a $1 billion contribution from TVA. The changes approved by the TVARS Board (1) suspended the TVA contribution requirements for 2010 through 2013, (2) reduced the calculation for COLA benefits for CY 2010 through CY 2013, (3) reduced the interest crediting rate for the fixed fund accounts, and (4) increased the eligibility age to receive COLAs from age 55 to 60 . The plaintiffs alleged that these changes violated their constitutional rights (due process, equal protection, and property rights), violated the Administrative Procedure Act, and breached statutory duties owed to the plaintiffs. TVA and plaintiffs filed cross motions for summary judgment. In August 2015, the court granted TVA’s motion for summary judgment and dismissed the case with prejudice. In September 2015, the plaintiffs appealed this decision to the United States Court of Appeals for the Sixth Circuit (the "Sixth Circuit"). Cases Involving Gallatin Fossil Plant CCR Facilities. In January 2015, the State of Tennessee filed a lawsuit against TVA in the Chancery Court for Davidson County, Tennessee. The lawsuit alleges that waste materials have been released into waters of the state from coal combustion residual ("CCR") facilities at Gallatin Fossil Plant ("Gallatin") in violation of the Tennessee Water Quality Control Act and the Tennessee Solid Waste Disposal Act. TDEC is seeking injunctive relief as well as civil penalties of up to $17,000 per day for each day TVA is found to have violated the statutes. In February 2015, the court issued an order allowing the Tennessee Scenic Rivers Association ("TSRA") and the Tennessee Clean Water Network ("TCWN") to intervene in the case. In April 2015, TSRA and TCWN filed a lawsuit against TVA in the United States District Court for the Middle District of Tennessee alleging that waste materials have been released into the Cumberland River from CCR facilities at Gallatin in violation of the Clean Water Act. The plaintiffs are seeking injunctive relief and civil penalties of up to $37,500 per violation per day. In January 2016, following negotiations among the parties, the state court issued an agreed temporary injunction requiring TVA to conduct further environmental studies at Gallatin and develop any necessary corrective action plan in cooperation with the other parties. The injunction on its terms is not intended to impact the federal lawsuit. Case Involving the NRC Waste Confidence Decision on Spent Nuclear Fuel Storage. In June 2012, The U.S. Court of Appeals for the District of Columbia Circuit ("D.C. Circuit") vacated the NRC's updated Waste Confidence Decision ("WCD") . The WCD is a generic determination by the NRC that spent nuclear fuel can be safely managed until a permanent off-site repository is established; this determination has been a key component of NRC licensing activities since 1984. In August 2014, the NRC issued its final rule on continued storage of spent nuclear fuel (the "Continued Storage Rule"), which replaced the WCD. Several petitions for review were filed in October 2014 in the D.C. Circuit challenging the Continued Storage Rule. Administrative Proceeding Regarding Renewal of Operating License for Sequoyah Nuclear Plant. In May 2013, the Blue Ridge Environmental Defense League ("BREDL") , the Bellefonte Efficiency and Sustainability Team ("BEST") , and Mothers Against Tennessee River Radiation filed a petition with the NRC opposing the renewal of the operating license for Sequoyah Units 1 and 2. The petition contained eight specific contentions challenging the adequacy of the license renewal application that TVA submitted to the NRC in January 2013. TVA filed a response with the Atomic Safety and Licensing Board ("ASLB") opposing the admission of all eight of the petitioners' contentions. In July 2013, the ASLB concluded that BREDL was the only one of the three petitioners that had standing to intervene in this proceeding. The ASLB also held that seven of the contentions were inadmissible, and held one portion of the remaining contention related to the WCD in abeyance pending further direction from the NRC. In September 2014, the ASLB denied BREDL's contention related to the WCD. Following the publication of the Continued Storage Rule, BREDL filed a petition with the NRC seeking suspension of the issuance of a final decision in the Sequoyah proceeding and a motion with the ASLB seeking leave to file a new, late-filed contention related to the Continued Storage Rule. The NRC rejected this petition in February 2015. See Case Involving the NRC Waste Confidence Decision on Spent Nuclear Fuel Storage . With the NRC’s rejection of the final pending contention, the ASLB issued an order terminating the administrative proceeding in March 2015. In April 2015, BREDL filed motions with the NRC to reopen the record and to admit a new contention arguing that the environmental impact statement for Sequoyah must incorporate by reference the generic environmental impact statement released in connection with the Continued Storage Rule. The NRC rejected these motions in June 2015. In August 2015, BREDL asked the D.C. Circuit to review the NRC's decision after the court issues a decision on BREDL's petition for review challenging the Continued Storage Rule. The NRC issued the license renewal of the facility operating licenses for both units effective September 28, 2015. Administrative Proceedings Regarding Bellefonte Units 3 and 4 . TVA submitted its combined construction and operating license ("COL") application for two Advanced Passive 1000 reactors at Bellefonte Nuclear Plant ("Bellefonte") Units 3 and 4 to the NRC in October 2007. In June 2008, BEST, BREDL, and Southern Alliance for Clean Energy ("SACE") submitted a joint petition for intervention and a request for a hearing. The ASLB denied standing to BEST and admitted four of the 20 contentions submitted by BREDL and SACE. The NRC reversed the ASLB's decision to admit two of the four contentions, leaving only two contentions (concerning the estimated costs of the new nuclear plant and the impact of the facility's operations on aquatic ecology) to be litigated in a future hearing. In January 2012, TVA notified the ASLB that the NRC had placed the COL in “suspended” status indefinitely at TVA's request, and TVA requested that the ASLB hold the proceeding in abeyance pending a decision by TVA regarding the best path forward with regards to the COL. In April 2012, the ASLB issued an order maintaining the proceeding in "active" status, but amending the disclosure schedule. The ASLB again modified the disclosure schedule in December 2015. Administrative Proceedings Regarding Watts Bar Unit 2 . In October 2015, the NRC issued the operating license for Watts Bar Unit 2. In November 2015, SACE filed a petition in the D.C. Circuit seeking review of the issuance of the operating license for Watts Bar Unit 2. TVA moved to intervene in the proceeding in December 2015. The case has been held in abeyance while the D.C. Circuit resolves the ongoing challenge to the Continued Storage Rule. National Environmental Policy Act Challenge at Paradise Fossil Plant . To comply with the EPA’s Mercury and Air Toxics Standards, TVA chose to retire two coal-fired units at Paradise Fossil Plant and replace them with natural gas generation. Prior to making this decision, TVA completed an Environmental Assessment in November 2013 under National Environmental Policy Act ("NEPA") . In July 2014, the Kentucky Coal Association and several individuals filed suit in the United States District Court for the Western District of Kentucky alleging that TVA violated NEPA and the Energy Policy Act of 1992 in deciding to switch to natural gas generation. The plaintiffs demand that TVA prepare an Environmental Impact Statement, and are asking the court to preliminarily enjoin TVA from taking any further action relating to these matters pending compliance with NEPA. The court denied the plaintiffs' motion for a preliminary injunction in December 2014 and dismissed the case in February 2015. In March 2015, the plaintiffs appealed the court's decision to the Sixth Circuit, and in October 2015, the Sixth Circuit affirmed the court's decision. Kingston Fossil Plant NPDES Permit Administrative Appeal . The Sierra Club filed a challenge to the National Pollutant Discharge Elimination System ("NPDES") permit issued by Tennessee for the scrubber-gypsum pond discharge at Kingston in November 2009 before the Tennessee Board of Water Quality, Oil and Gas ("TN Board") . TDEC is the defendant in the challenge, and TVA has intervened in support of TDEC's decision to issue the permit. Bull Run Fossil Plant NPDES Permit Administrative Appeal. SACE and the TCWN filed a challenge to the NPDES permit for the Bull Run Fossil Plant in November 2010. TDEC is the defendant in the challenge, and TVA's motion to intervene to support TDEC's decision to issue the permit was granted in January 2011. At the contested case hearing in October 2013, the TN Board granted TDEC's and TVA's joint motion for involuntary dismissal following the conclusion of the petitioners' presentation of evidence. In December 2013, TCWN and SACE filed a petition for review of the TN Board's decision in the Chancery Court for Davidson County, Tennessee. In March 2015, the court issued a final order affirming the TN Board's decision, and the petitioners subsequently appealed the court's decision to the Tennessee Court of Appeals. Gallatin Fossil Plant NPDES Permit Administrative Appeal . SACE, TCWN, and the Sierra Club filed a challenge to the NPDES permit for Gallatin in June 2012. TDEC is the defendant in the challenge. TVA's motion to intervene was granted in September 2012. Following discovery, SACE, TCWN, and the Sierra Club voluntarily dismissed seven of the eight claims asserted in their petition. TVA moved to dismiss the remaining claim, and the Administrative Law Judge ("ALJ") assigned to the matter granted TVA’s motion and dismissed the case. On November 7, 2014, SACE, TWCN, and the Sierra Club filed a petition for review of the ALJ's dismissal in the Chancery Court for Davidson County, Tennessee. In February 2015, the court issued a final order affirming that the Gallatin NPDES permit was lawfully issued. In March 2015, the petitioners appealed the court's decision to the Tennessee Court of Appeals.

Summary of Significant Accoun23

Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Dec. 31, 2015
Accounting Policies [Abstract]
General	General The Tennessee Valley Authority ("TVA") is a corporate agency and instrumentality of the United States that was created in 1933 by legislation enacted by the United States ("U.S.") Congress in response to a request 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 United States, 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 nine 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 to provide recreational opportunities, adequate water supply, improved water quality, natural resource protection, and economic development. 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 ("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 of Directors (the "TVA Board") as authorized by the Tennessee Valley Authority Act of 1933, as amended, 16 U.S.C. §§ 831-831ee (the “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. 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. TVA fulfilled its requirement to repay $ 1.0 billion of the Power Program Appropriation Investment in 2014.
Fiscal Year	Fiscal Year TVA's fiscal year ends September 30. Years ( 2016 , 2015 , 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 future 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 any of the other factors described above cease to be applicable, TVA would no longer be considered to be a regulated entity and would be required to write off these costs. Most 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, 2015 , and the notes thereto, which are contained in TVA's Annual Report on Form 10-K for the year ended September 30, 2015 (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 in the interim financial statements. The accompanying consolidated interim financial statements include the accounts of TVA and three variable interest entities ("VIEs") , of which TVA is the primary beneficiary. See Note 7 . Intercompany balances and transactions have been eliminated in consolidation.
Use of Estimates	Use of Estimates The preparation of financial statements requires TVA to estimate the effects of various matters that are inherently uncertain as of the date of the consolidated financial statements. Although the consolidated financial statements are prepared in conformity with GAAP, TVA is required to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities, and the amounts of revenues and expenses reported during the reporting period. Each of these estimates varies in regard to the level of judgment involved and its potential impact on TVA's financial results. Estimates are deemed 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.
Reclassifications	Reclassifications Certain historical amounts have been reclassified in the Consolidated Statements of Cash Flows for the three months ended December 31, 2014 . Amounts previously presented in Cash flows from operating activities as Environmental cleanup costs – Kingston ash spill – non cash of $ 12 million and Environmental cleanup costs – Kingston ash spill of $ (9) million for the three months ended December 31, 2014 , are currently reported in Other, net. In the Consolidated Balance Sheet at September 30, 2015 , TVA reclassified $80 million of debt issuance costs previously presented in Other long-term assets and presented $67 million as a reduction to Long-term power bonds, net and $13 million as a reduction to Long-term debt, net of variable interest entities. See Note 2 – Debt Issuance Costs for additional information.
Allowance for Uncollectible Accounts	Allowance for Uncollectible Accounts The allowance for uncollectible accounts reflects TVA's estimate of probable losses inherent in its accounts and loans receivable balances. TVA determines the allowance based on known accounts, historical experience, and other currently available information including events such as customer bankruptcy and/or a customer failing to fulfill payment arrangements. It also reflects TVA's corporate credit department's assessment of the financial condition of customers and the credit quality of the receivables. The allowance for uncollectible accounts was $ 1 million at both December 31, 2015 and September 30, 2015 , for accounts receivable. Additionally, loans receivable of $ 135 million and $ 129 million at December 31, 2015 and September 30, 2015 , respectively, are included in Accounts receivable, net and Other long-term assets, for the current and long-term portions, respectively, and reported net of allowances for uncollectible accounts of $ 8 million at both December 31, 2015 and September 30, 2015 .
Depreciation	Depreciation Depreciation expense was $ 364 million and $ 380 million for the three months ended December 31, 2015 , and December 31, 2014 , respectively. In September 2015, the NRC approved renewed licenses for Sequoyah Nuclear Plant ("Sequoyah") Units 1 and 2, which allow both units to operate for an additional 20 years and TVA adjusted prospectively the Sequoyah depreciation rate. These license extensions contributed to $22 million of the decrease in depreciation expense for the three months ended December 31, 2015, as compared to the three months ended December 31, 2014 as a result of this change in estimate.
Blended Low-Enriched Uranium Program	Blended Low-Enriched Uranium Program Under the blended low-enriched uranium ("BLEU") program, TVA, the U.S. Department of Energy ("DOE") , and certain nuclear fuel contractors have entered into agreements providing for the DOE's surplus of enriched uranium to be blended with other uranium down to a level that allows the blended uranium to be fabricated into fuel that can be used in nuclear power plants. Under the terms of an interagency agreement between TVA and the DOE, in exchange for supplying highly enriched uranium materials to the appropriate third-party fuel processors for processing into usable BLEU fuel for TVA, the DOE participates to a degree in the savings generated by TVA’s use of this blended nuclear fuel. Over the life of the program, TVA projects that the DOE’s share of savings generated by TVA’s use of this blended nuclear fuel could result in payments to the DOE of as much as $ 162 million . TVA accrues an obligation with each BLEU reload batch related to the portion of the ultimate future payments estimated to be attributable to the BLEU fuel currently in use. At December 31, 2015 , TVA had paid out approximately $ 131 million for this program, and the obligation recorded was $ 12 million .

Variable Interest Entities (Pol

Variable Interest Entities (Policies)	3 Months Ended
	Dec. 31, 2015
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
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 variable interest entity, 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 several entities and as such is required to account for the VIEs on a consolidated basis.

Asset Retirement Obligations As

Asset Retirement Obligations Asset Retirement Obligations (Policies)	3 Months Ended
	Dec. 31, 2015
Asset Retirement Obligation Disclosure [Abstract]
Asset Retirement Obligations, Policy [Policy Text Block]	To estimate its decommissioning obligation related to its nuclear generating stations, TVA uses a probability-weighted, discounted cash flow model which, on a unit-by-unit basis, considers multiple outcome scenarios that include significant estimations and assumptions. Those assumptions include (1) estimates of the cost of decommissioning, (2) the method of decommissioning and the timing of the related cash flows, (3) the license period of the nuclear plant, considering the probability of license extensions, (4) cost escalation factors, and (5) the credit adjusted risk free rate to measure the obligation at the present value of the future estimated costs. TVA has ascribed probabilities to two different decommissioning methods related to its nuclear decommissioning obligation estimate: the DECON method and the SAFESTOR method. The DECON method requires radioactive contamination to be removed from a site and safely disposed of or decontaminated to a level that permits the site to be released for unrestricted use shortly after it ceases operation. The SAFSTOR method allows nuclear facilities to be placed and maintained in a condition that allows the facilities to be safely stored and subsequently decontaminated to levels that permit release for unrestricted use. TVA bases its nuclear decommissioning estimates on site-specific cost studies. These studies will be updated for each of TVA’s nuclear units at least every 5 years and were most recently performed in 2014. In April 2015, the EPA published its final rule governing coal combustion residuals, which regulates landfill and impoundment location, design, and operations; dictates certain pond-closure conditions; and establishes groundwater monitoring and closure and post-closure standards. As a result of these rules, TVA recorded certain adjustments to its ARO liabilities in 2015. TVA continues to evaluate the impact of the rule on its operations, including cost and timing estimates of related projects. As a result, further adjustments to its ARO liabilities may be required as estimates are refined.

Accounts Receivable, Net (Table

Accounts Receivable, Net (Tables)	3 Months Ended
	Dec. 31, 2015
Accounts Receivable, Net [Abstract]
Accounts Receivable, Net	The table below summarizes the types and amounts of TVA’s accounts receivable: Accounts Receivable, Net At December 31, 2015 At September 30, 2015 Power receivables $ 1,165 $ 1,509 Other receivables 75 92 Allowance for uncollectible accounts (1 ) (1 ) Accounts receivable, net $ 1,239 $ 1,600

Inventories, Net (Tables)

Inventories, Net (Tables)	3 Months Ended
	Dec. 31, 2015
Inventory, Net [Abstract]
Inventories, Net	The table below summarizes the types and amounts of TVA’s inventories: Inventories, Net At December 31, 2015 At September 30, 2015 Materials and supplies inventory $ 685 $ 651 Fuel inventory 499 414 Emission allowance inventory, net 15 13 Allowance for inventory obsolescence (53 ) (47 ) Inventories, net $ 1,146 $ 1,031

Other Long-Term Assets (Tables)

Other Long-Term Assets (Tables)	3 Months Ended
	Dec. 31, 2015
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 At December 31, 2015 At September 30, 2015 EnergyRight ® receivables $ 123 $ 124 Loans and other long-term receivables, net 132 126 Prepaid capacity payments 50 52 Currency swap asset, net 9 25 Commodity contract derivative assets 4 1 Other 92 75 Other long-term assets $ 410 $ 403

Regulatory Assets and Liabili29

Regulatory Assets and Liabilities (Tables)	3 Months Ended
	Dec. 31, 2015
Regulatory Assets and Liabilities Disclosure [Abstract]
Regulatory Assets and Liabilities	Components of regulatory assets and regulatory liabilities are summarized in the table below: Regulatory Assets and Liabilities At December 31, 2015 At September 30, 2015 Current regulatory assets Deferred nuclear generating units $ 237 $ 237 Unrealized losses on commodity derivatives 169 162 Environmental agreements 49 47 Environmental cleanup costs - Kingston ash spill 43 43 Fuel cost adjustment receivable 3 15 Other current regulatory assets 2 2 Total current regulatory assets 503 506 Non-current regulatory assets Deferred pension costs and other post-retirement benefits costs 5,556 5,565 Unrealized losses on interest rate derivatives 1,147 1,236 Nuclear decommissioning costs 970 1,003 Environmental cleanup costs - Kingston ash spill 331 348 Non-nuclear decommissioning costs 835 828 Deferred nuclear generating units 1,004 1,042 Environmental agreements 41 55 Unrealized losses on commodity derivatives 81 63 Other non-current regulatory assets 272 278 Total non-current regulatory assets 10,237 10,418 Total regulatory assets $ 10,740 $ 10,924 Current regulatory liabilities Fuel cost adjustment tax equivalents $ 157 $ 164 Fuel cost adjustment payable 25 — Total current regulatory liabilities 182 164 Non-current regulatory liabilities Unrealized gains on commodity derivatives 4 2 Total non-current regulatory liabilities 4 2 Total regulatory liabilities $ 186 $ 166

Variable Interest Entities (Tab

Variable Interest Entities (Tables)	3 Months Ended
	Dec. 31, 2015
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Summary of Impact of VIEs on Consolidated Balance Sheets	The financial statement items attributable to carrying amounts and classifications of JSCCG, Holdco, and SCCG as of December 31, 2015 and September 30, 2015 , as reflected in the consolidated balance sheets are as follows: Summary of Impact of VIEs on Consolidated Balance Sheets At December 31, 2015 At September 30, 2015 Current liabilities of VIE Accrued interest of VIE $ 27 $ 12 Current portion of membership interests of VIE subject to mandatory redemption 2 2 Current maturities of long-term debt of VIE 33 33 Total current liabilities of VIE 62 47 Other liabilities of VIE Membership interests of VIE subject to mandatory redemption 35 35 Long-term debt of VIE, net Long-term debt of VIE, net 1,233 1,233 Total liabilities of VIE $ 1,330 $ 1,315

Other Long-Term Liabilities (Ta

Other Long-Term Liabilities (Tables)	3 Months Ended
	Dec. 31, 2015
Other Liabilities, Noncurrent [Abstract]
Other Long-Term Liabilities	The table below summarizes the types and amounts of Other long-term liabilities: Other Long-Term Liabilities At December 31, 2015 At September 30, 2015 Interest rate swap liabilities $ 1,538 $ 1,627 EnergyRight ® financing obligation 146 148 Environmental agreements liability 41 55 Currency swap liabilities 58 47 Membership interests of VIE subject to mandatory redemption 35 35 Commodity contract derivative liabilities 46 17 Commodity swap derivative liabilities 9 10 Other 276 280 Total other long-term liabilities $ 2,149 $ 2,219

Debt and Other Obligations (Tab

Debt and Other Obligations (Tables)	3 Months Ended
	Dec. 31, 2015
Debt Disclosure [Abstract]
Debt Outstanding	Total debt outstanding at December 31, 2015 , and September 30, 2015 , consisted of the following: Debt Outstanding At December 31, 2015 At September 30, 2015 Short-term debt Short-term debt, net $ 1,504 $ 1,034 Current maturities of long-term debt of variable interest entities 33 33 Current maturities of power bonds 554 32 Total current debt outstanding, net 2,091 1,099 Long-term debt Long-term debt of variable interest entities 1,246 1,246 Long-term power bonds (1) 22,242 22,792 Unamortized discounts, premiums, issue costs, and other (184 ) (188 ) Total long-term debt, net 23,304 23,850 Total outstanding debt $ 25,395 $ 24,949 Note (1) Includes net exchange gain from currency transactions of $ 44 million at December 31, 2015 and $ 21 million at September 30, 2015 .
Debt Securities Activity	The table below summarizes the long-term debt securities activity for the period from October 1, 2015, to December 31, 2015 : Debt Securities Activity Date Amount Interest Rate Redemptions/Maturities electronotes ® First Quarter 2016 $ 1 2.65 % 2009 Series A November 2015 2 2.25 % 2009 Series B December 2015 1 3.77 % Total redemptions/maturities of power bonds 4 Total redemptions/maturities of debt $ 4 Note (1) All redemptions were at 100 percent of par.
Credit Facility Agreements
Summary of Long-Term Credit Facilities	The following table provides additional information regarding TVA's funding available in the form of three long-term credit facilities: Summary of Long-Term Credit Facilities At December 31, 2015 (in billions) Maturity Date Facility Limit Letters of Credit Outstanding Cash Borrowings Availability February 2020 $ 0.5 $ 0.5 $ — $ — June 2020 1.0 0.3 — 0.7 September 2020 1.0 0.3 — 0.7 Total $ 2.5 $ 1.1 $ — $ 1.4

Asset Retirement Obligations (T

Asset Retirement Obligations (Tables)	3 Months Ended
	Dec. 31, 2015
Asset Retirement Obligation Disclosure [Abstract]
Asset Retirement Obligation Activity	Asset Retirement Obligation Activity Nuclear Non-Nuclear Total Balance at September 30, 2015 $ 2,187 $ 1,656 $ 3,843 Settlements — (22 ) (22 ) Change in estimate — (7 ) (7 ) Accretion (recorded as regulatory asset) 26 11 37 Balance at December 31, 2015 $ 2,213 $ 1,638 $ 3,851 (1 ) Note (1) The current portion of ARO in the amount of $ 183 million is included in Accounts payable and accrued liabilities at December 31, 2015 .

Risk Management Activities an34

Risk Management Activities and Derivative Transactions (Tables)	3 Months Ended
	Dec. 31, 2015
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 OCI Three Months Ended Derivatives in Cash Flow Hedging Relationship Objective of Hedge Transaction Accounting for Derivative Hedging Instrument 2015 2014 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 $ (27 ) $ (15 ) Summary of Derivative Instruments That Receive Hedge Accounting Treatment (part 2) Amount of Gain (Loss) Reclassified from OCI to Interest Expense Three Months Ended Derivatives in Cash Flow Hedging Relationship 2015 2014 Currency swaps $ (24 ) $ (38 ) Note There were no ineffective portions or amounts excluded from effectiveness testing for any of the periods presented. Based on forecasted foreign currency exchange rates, TVA expects to reclassify approximately $ 44 million of losses from AOCI to interest expense within the next twelve months to offset amounts anticipated to be recorded in interest expense related to exchange gain 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 Three Months Ended December 31 ( 1) Derivative Type Objective of Derivative Accounting for Derivative Instrument 2015 2014 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 assets or liabilities. Realized gains and losses are recognized in interest expense when payments are made or received on the swap settlement dates. $ (28 ) $ (29 ) Commodity contract derivatives To protect against fluctuations in market prices of purchased coal or natural gas (price risk) Mark-to-market gains and losses are recorded as regulatory assets or liabilities. Realized gains and losses due to contract settlements are recognized in fuel expense as incurred. — — Commodity derivatives under financial trading program ("FTP") To protect against fluctuations in market prices of purchased commodities (price risk) Mark-to-market gains and losses are recorded as regulatory assets or liabilities. Realized gains and losses are recognized in fuel expense or purchased power expense when the related commodity is used in production. (36 ) (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 was no related gain (loss) recognized in income for these unrealized gains (losses) for the three months ended December 31, 2015 and 2014 .
Fair Value of TVA Derivatives	Fair Values of TVA Derivatives At December 31, 2015 At September 30, 2015 Derivatives That Receive Hedge Accounting Treatment Balance Balance Sheet Presentation Balance Balance Sheet Presentation Currency swaps £200 million Sterling $ (43 ) Other long-term liabilities $ (41 ) Other long-term liabilities £250 million Sterling 9 Other long-term assets 25 Other long-term assets £150 million Sterling (15 ) Other long-term liabilities (6 ) Other long-term liabilities At December 31, 2015 At September 30, 2015 Derivatives That Do Not Receive Hedge Accounting Treatment Balance Balance Sheet Presentation Balance Balance Sheet Presentation Interest rate swaps $1.0 billion notional (1,115 ) Other long-term liabilities (1,177 ) Other long-term liabilities $476 million notional (412 ) Other long-term liabilities (438 ) Other long-term liabilities $42 million notional (11 ) Other long-term liabilities (12 ) Other long-term liabilities Commodity contract derivatives (138 ) Other long-term assets $4; Other long-term liabilities $(46); Accounts payable and accrued liabilities $(96) (97 ) Other long-term assets $1; Other long-term liabilities $(17); Accounts payable and accrued liabilities $(81) FTP Derivatives under FTP (1) (101 ) Other current assets $(80); Other long-term liabilities $(9); Accounts payable and accrued liabilities $(12) (116 ) Other current assets $(89); Other long-term liabilities $(10); Accounts payable and accrued liabilities $(17) Note (1) Fair values of certain derivatives under the FTP that were in net liability positions totaling $80 million and $ 89 million at December 31, 2015 and September 30, 2015 , respectively, are recorded in TVA's margin cash accounts in Other current assets. These derivatives are transacted with futures commission merchants, and cash deposits have been posted to the margin cash accounts held with each futures commission merchant to offset the net liability positions in full.
Currency Swaps Outstanding	TVA had the following currency swaps outstanding as of December 31, 2015 : Currency Swaps Outstanding At December 31, 2015 Effective Date of Currency Swap Contract Associated TVA Bond Issues Currency Exposure Expiration Date of Swap Overall Effective Cost to TVA 1999 £200 million 2021 5.81% 2001 £250 million 2032 6.59% 2003 £150 million 2043 4.96%
Commodity Contract Derivatives	Commodity Contract Derivatives At December 31, 2015 At September 30, 2015 Number of Contracts Notional Amount Fair Value (MtM) Number of Contracts Notional Amount Fair Value ( MtM ) Coal contract derivatives 12 20 million tons $ (123 ) 14 19 million tons $ (98 ) Natural gas contract derivatives 30 132 million mmBtu $ (15 ) 33 134 million mmBtu $ 1
Derivatives Under Financial Trading Program	Derivatives Under Financial Trading Program At December 31, 2015 At September 30, 2015 Notional Amount Fair Value (MtM) (in millions) Notional Amount Fair Value (MtM) (in millions) Natural gas (in mmBtu) Swap contracts 40,977,500 $ (101 ) 51,495,000 $ (116 ) Note Fair value amounts presented are based on the net commodity position with the counterparty. Notional amounts disclosed represent the net absolute value of contractual amounts.
Financial Trading Program Unrealized Gains (Losses)	TVA experienced the following unrealized and realized gains and losses related to the FTP at the dates and during the periods, as applicable, set forth in the tables below: Financial Trading Program Unrealized Gains (Losses) At December 31, 2015 At September 30, 2015 FTP unrealized gains (losses) deferred as regulatory liabilities (assets) Natural gas $ (101 ) $ (116 )
Financial Trading Program Realized Gains (Losses)	Financial Trading Program Realized Gains (Losses) For the Three Months Ended 2015 2014 Decrease (increase) in fuel expense Natural gas $ (29 ) $ (12 ) Fuel oil/crude oil — 1 Financial Trading Program Realized Gains (Losses) For the Three Months Ended 2015 2014 Decrease (increase) in purchased power expense Natural gas $ (7 ) $ (3 )
Offsetting of Derivative Assets and Liabilities	The amounts of TVA's derivative instruments as reported in the Consolidated Balance Sheets as of December 31, 2015 , and September 30, 2015 , are shown in the table below: Derivative Assets and Liabilities As of December 31, 2015 Gross Amounts of Recognized Assets/Liabilities Gross Amounts Offset in the Balance Sheet (1) Net Amounts of Assets/Liabilities Presented in the Balance Sheet (2) Assets Currency swap(s) (3)(4) $ 9 $ — $ 9 Commodity derivatives under FTP 36 (36 ) — Total derivatives subject to master netting or similar arrangement 45 (36 ) 9 Total derivatives not subject to master netting or similar arrangement 4 — 4 Total $ 49 $ (36 ) $ 13 Liabilities Currency swap(s) (4) $ 58 $ — $ 58 Interest rate swaps (4) 1,538 — 1,538 Commodity derivatives under FTP 137 (116 ) 21 Total derivatives subject to master netting or similar arrangement 1,733 (116 ) 1,617 Total derivatives not subject to master netting or similar arrangement 142 — 142 Total $ 1,875 $ (116 ) $ 1,759 As of September 30, 2015 Gross Amounts of Recognized Assets/Liabilities Gross Amounts Offset in the Balance Sheet (1) Net Amounts of Assets/Liabilities Presented in the Balance Sheet (2) Assets Currency swap(s) (3)(4) $ 25 $ — $ 25 Commodity derivatives under FTP 49 (49 ) — Total derivatives subject to master netting or similar arrangement 74 (49 ) 25 Total derivatives not subject to master netting or similar arrangement 1 — 1 Total $ 75 $ (49 ) $ 26 Liabilities Currency swap(s) (4) $ 47 $ — $ 47 Interest rate swaps (4) 1,627 — 1,627 Commodity derivatives under FTP 165 (138 ) 27 Total derivatives subject to master netting or similar arrangement 1,839 (138 ) 1,701 Total derivatives not subject to master netting or similar arrangement 98 — 98 Total $ 1,937 $ (138 ) $ 1,799 Notes (1) Amounts primarily include counterparty netting of derivative contracts, margin account deposits for futures commission merchants transactions, and cash collateral received or paid in accordance with the accounting guidance for derivatives and hedging transactions. (2) There are no derivative contracts subject to a master netting arrangement or similar agreement which are not offset in the balance sheets. (3) At December 31, 2015 and September 30, 2015 , there were no securities posted by a counterparty on TVA's behalf to partially secure the asset position(s) of currency swaps in accordance with the collateral requirements for these derivatives. (4) Letters of credit of approximately $ 1.1 billion were posted as collateral at both December 31, 2015 and September 30, 2015 , to partially secure the liability positions of one of the currency swaps and one of the interest rate swaps in accordance with the collateral requirements for these derivatives. TVA held $ 20 million and $15 million cash collateral in excess of collateral requirements at December 31, 2015 and September 30, 2015 , respectively. Cash collateral held in excess of collateral requirements is recorded in Restricted cash and investments with a corresponding obligation of the same amount recorded in Accounts payable and accrued liabilities.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
	Dec. 31, 2015
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 Investments Gains (Losses)	TVA recorded unrealized gains and losses related to its trading securities held as of the end of each period as follows: Unrealized Investment Gains (Losses) For the Three Months Ended Financial Statement Presentation 2015 2014 SERP Other income (expense) $ — $ (1 ) LTDCP Other income (expense) — (1 ) NDT Regulatory asset 39 23 ART Regulatory asset 12 6
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 as of December 31, 2015 , and September 30, 2015 . Financial assets and liabilities have been classified in their entirety based on the lowest level of input that is significant to the fair value measurement. TVA's assessment of the significance of a particular input to the fair value measurement requires judgment and may affect the determination of the fair value of the assets and liabilities and their classification in the fair value hierarchy levels. Fair Value Measurements At December 31, 2015 Assets Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total Investments Equity securities $ 185 $ — $ — $ 185 Debt securities U.S. government corporations and agencies 200 39 — 239 Corporate debt securities — 254 — 254 Residential mortgage-backed securities — 16 — 16 Commercial mortgage-backed securities — 5 — 5 Collateralized debt obligations — 28 — 28 Institutional mutual funds 88 — — 88 Forward debt securities contracts — (8 ) — (8 ) Private partnerships measured at net asset value (1) — — — 245 Commingled funds measured at net asset value (1) — — — 1,031 Total investments 473 334 — 2,083 Currency swap(s) (2) — 9 — 9 Commodity contract derivatives — 4 — 4 Commodity derivatives under FTP (2) Swap contracts — — — — Total $ 473 $ 347 $ — $ 2,096 Liabilities Quoted Prices in Active Markets for Identical Liabilities (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total Currency swap(s) (2) $ — $ 58 $ — $ 58 Interest rate swaps — 1,538 — 1,538 Commodity contract derivatives — 19 123 142 Commodity derivatives under FTP (2) Swap contracts — 21 — 21 Total $ — $ 1,636 $ 123 $ 1,759 Notes (1) Certain investments that are measured at fair value using the net asset value 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 in the consolidated balance sheets. (2) Due to the right of setoff and method of settlement, TVA elects to record commodity derivatives under the FTP based on its net commodity position with the counterparty or FCM. Deposits are made to TVA's margin cash accounts held with each FCM to offset any net liability positions in full for derivatives that are transacted with FCMs. TVA records currency swaps net of cash collateral received from or paid to the counterparty, to the extent such amount is not recorded in Accounts payable and accrued liabilities. See Note 12 — Offsetting of Derivative Assets and Liabilities . Fair Value Measurements At September 30, 2015 Assets Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total Investments Equity securities $ 166 $ — $ — $ 166 Debt securities U.S. government corporations and agencies 203 31 — 234 Corporate debt securities — 225 — 225 Residential mortgage-backed securities — 17 — 17 Commercial mortgage-backed securities — 7 — 7 Collateralized debt obligations — 29 — 29 Institutional mutual funds 91 — — 91 Forward debt securities contracts — (59 ) — (59 ) Private partnerships measured at net asset value (1) — — — 240 Commingled funds measured at net asset value (1) — — — 1,061 Total investments 460 250 — 2,011 Currency swap(s) (2) — 25 — 25 Commodity contract derivatives — 1 — 1 Commodity derivatives under FTP (2) Swap contracts — — — — Total $ 460 $ 276 $ — $ 2,037 Liabilities Quoted Prices in Active Markets for Identical Liabilities (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total Currency swap(s) (2) $ — $ 47 $ — $ 47 Interest rate swaps — 1,627 — 1,627 Commodity contract derivatives — — 98 98 Commodity derivatives under FTP (2) Swap contracts — 27 — 27 Total $ — $ 1,701 $ 98 $ 1,799 Notes (1) Certain investments that are measured at fair value using the net asset value 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 in the consolidated balance sheets. (2) Due to the right of setoff and method of settlement, TVA elects to record commodity derivatives under the FTP based on its net commodity position with the counterparty or FCM. Deposits are made to TVA's margin cash accounts held with each FCM to offset any net liability positions in full for derivatives that are transacted with FCMs. TVA records currency swaps net of cash collateral received from or paid to the counterparty, to the extent such amount is not recorded in Accounts payable and accrued liabilities. See Note 12 — Offsetting of Derivative Assets and Liabilities .
Fair Value Measurements Using Significant Unobservable Inputs	The following table presents a reconciliation of all commodity contract derivatives measured at fair value on a recurring basis using significant unobservable inputs (Level 3): Fair Value Measurements Using Significant Unobservable Inputs Commodity Contract Derivatives Balance At September 30, 2014 $ (85 ) Purchases — Issuances — Sales — Settlements — Net unrealized gains (losses) deferred as regulatory assets and liabilities (22 ) Balance at December 31, 2014 $ (107 ) Balance at September 30, 2015 $ (98 ) Purchases — Issuances — Sales — Settlements — Net unrealized gains (losses) deferred as regulatory assets and liabilities (25 ) Balance at December 31, 2015 $ (123 )
Quantitative Information about Level 3 Fair Value Measurements	The following table presents quantitative information related to the significant unobservable inputs used in the measurement of fair value of TVA's assets and liabilities classified as Level 3 in the fair value hierarchy: Quantitative Information about Level 3 Fair Value Measurements Fair Value at December 31 2015 Valuation Technique(s) Unobservable Inputs Range Assets Commodity contract derivatives $ — Pricing model Coal supply and demand 0.8 - 1.0 billion tons/year Long-term market prices $9.83 - $121.51/ton Liabilities Commodity contract derivatives $ 123 Pricing model Coal supply and demand 0.8 - 1.0 billion tons/year Long-term market prices $9.83 - $121.51/ton Quantitative Information about Level 3 Fair Value Measurements Fair Value at September 30 2015 Valuation Technique(s) Unobservable Inputs Range Assets Commodity contract derivatives $ — Pricing model Coal supply and demand 0.8 - 1.0 billion tons/year Long-term market prices $10.64 - $103.41/ton Liabilities Commodity contract derivatives $ 98 Pricing model Coal supply and demand 0.8 - 1.0 billion tons/year Long-term market prices $10.64 - $103.41/ton
Estimated Values of Financial Instruments Not Recorded at Fair Value	The estimated fair values of TVA's financial instruments not recorded at fair value at December 31, 2015 , and September 30, 2015 , were as follows: Estimated Values of Financial Instruments Not Recorded at Fair Value At December 31, 2015 At September 30, 2015 Valuation Classification Carrying Amount Fair Value Carrying Amount Fair Value EnergyRight ® receivables (including current portion) Level 2 $ 155 $ 161 $ 156 $ 162 Loans and other long-term receivables, net (including current portion) Level 2 $ 135 $ 124 $ 129 $ 117 EnergyRight ® financing obligation (including current portion) Level 2 $ 183 $ 205 $ 185 $ 208 Unfunded loan commitments Level 2 $ — $ 11 $ — $ 9 Membership interest of variable interest entity subject to mandatory redemption (including current portion) Level 2 $ 37 $ 46 $ 37 $ 47 Long-term outstanding power bonds (including current maturities), net Level 2 $ 22,625 $ 26,155 $ 22,649 $ 25,468 Long-term debt of variable interest entities (including current maturities), net Level 2 $ 1,266 $ 1,388 $ 1,266 $ 1,407

Other Income (Expense), Net (Ta

Other Income (Expense), Net (Tables)	3 Months Ended
	Dec. 31, 2015
Other Income and Expenses [Abstract]
Other Income (Expense), Net	Income and expenses not related to TVA’s operating activities are summarized in the following table: Other Income (Expense), Net For the Three Months Ended 2015 2014 Interest income $ 6 $ 6 External services 4 3 Gains (losses) on investments 3 1 Miscellaneous (1 ) (1 ) Total other income (expense), net $ 12 $ 9

Benefit Plans (Tables)

Benefit Plans (Tables)	3 Months Ended
	Dec. 31, 2015
Compensation and Retirement Disclosure [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 months ended December 31, 2015 , and 2014 , were as follows: Components of TVA’s Benefit Plans For the Three Months Ended December 31 Pension Benefits Other Post-Retirement Benefits 2015 2014 2015 2014 Service cost $ 32 $ 34 $ 4 $ 5 Interest cost 140 133 7 8 Expected return on plan assets (111 ) (109 ) — — Amortization of prior service credit (6 ) (5 ) (1 ) (2 ) Recognized net actuarial loss 73 69 2 2 Total net periodic benefit cost as actuarially determined 128 122 12 13 Amount capitalized due to actions of regulator (58 ) (51 ) — — Total net periodic benefit cost $ 70 $ 71 $ 12 $ 13

Summary of Significant Accoun38

Summary of Significant Accounting Policies General and Basis of Presentation (Details) People in Millions, $ in Millions	3 Months Ended		12 Months Ended
	Dec. 31, 2015USD ($)variable_interest_entitiesPeople	Dec. 31, 2014USD ($)	Sep. 30, 2016USD ($)	Sep. 30, 2015USD ($)	Sep. 30, 2014USD ($)
General and Basis of Presentation
Population of TVA's service area | People	9
Amount of appropriation investment that was repaid					$ 1,000
Number of variable interest entities | variable_interest_entities	3
Reclassification from Environmental cleanup costs-Kingston ash spill-non cash to Other, net		$ 12
Reclassification from Environmental cleanup costs-Kingston ash spill to Other, net		(9)
Reclassification from Other Long-Term Assets to Long-Term Debt, Net	$ 80
Reclassification from Other Long-Term Assets to Long-term Power Bonds, Net	67
Reclassification from Other Long-Term Assets to Long-Term Variable Interest Entities, Net	13
Allowance for uncollectible accounts, accounts receivable	1			$ 1
Loans receivable	124			117
Loans receivable, allowance	8			$ 8
Depreciation expense	364	$ 380
Change in depreciation	22
Total estimated amount of BLEU payments	162
Payments attributable to BLEU fuel program	131
BLEU fuel obligation	$ 12
Scenario, Forecast
General and Basis of Presentation
Change in depreciation			$ 83

Impact of New Accounting Stan39

Impact of New Accounting Standards and Interpretations Impact of New Accounting Standards and Interpretations (Details) $ in Millions	Sep. 30, 2015USD ($)
Other long-term assets
Unamortized debt issue cost of power bonds and variable interest entities	$ 80

Accounts Receivable, Net (Detai

Accounts Receivable, Net (Details) - USD ($) $ in Millions	Dec. 31, 2015	Sep. 30, 2015
Accounts Receivable, Net
Power receivables	$ 1,165	$ 1,509
Other receivables	75	92
Allowance for uncollectible accounts	(1)	(1)
Accounts receivable, net	$ 1,239	$ 1,600

Inventories, Net (Details)

Inventories, Net (Details) - USD ($) $ in Millions	Dec. 31, 2015	Sep. 30, 2015
Inventories, Net
Materials and supplies inventory	$ 685	$ 651
Fuel inventory	499	414
Emission allowance inventory, net	15	13
Allowance for inventory obsolescence	(53)	(47)
Inventories, net	$ 1,146	$ 1,031

Other Long-Term Assets (Details

Other Long-Term Assets (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2015		Sep. 30, 2015
Other Long-Term Assets
EnergyRight receivables	$ 161		$ 162
Currency swap asset, net	9	[1]	25	[2]
Total other long-term assets	$ 410		403
Energy Right Program
Other Long-Term Assets
Number of days in default	180 days
Other long-term assets
Other Long-Term Assets
EnergyRight receivables	$ 123		124
Loans and other long-term receivables, net	132		126
Prepaid capacity payments	50		52
Currency swap asset, net	9		25
Commodity contract derivative assets	4		1
Other	92		$ 75
Accounts Receivable [Member]
Other Long-Term Assets
EnergyRight receivables	$ 32
Minimum | Energy Right Program
Other Long-Term Assets
EnergyRight loan term	5 years
Maximum | Energy Right Program
Other Long-Term Assets
EnergyRight loan term	10 years
[1]	Due to the right of setoff and method of settlement, TVA elects to record commodity derivatives under the FTP based on its net commodity position with the counterparty or FCM. Deposits are made to TVA's margin cash accounts held with each FCM to offset any net liability positions in full for derivatives that are transacted with FCMs. TVA records currency swaps net of cash collateral received from or paid to the counterparty, to the extent such amount is not recorded in Accounts payable and accrued liabilities. See Note 12 — Offsetting of Derivative Assets and Liabilities.
[2]	Due to the right of setoff and method of settlement, TVA elects to record commodity derivatives under the FTP based on its net commodity position with the counterparty or FCM. Deposits are made to TVA's margin cash accounts held with each FCM to offset any net liability positions in full for derivatives that are transacted with FCMs. TVA records currency swaps net of cash collateral received from or paid to the counterparty, to the extent such amount is not recorded in Accounts payable and accrued liabilities. See Note 12 — Offsetting of Derivative Assets and Liabilities.

Regulatory Assets and Liabili43

Regulatory Assets and Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2015	Sep. 30, 2015
Regulatory Assets and Liabilities
Current regulatory assets	$ 503	$ 506
Non-current regulatory assets	10,237	10,418
Regulatory assets	10,740	10,924
Current regulatory liabilities	182	164
Non-current regulatory liabilities	4	2
Regulatory liabilities	186	166
Fuel cost adjustment tax equivalents
Regulatory Assets and Liabilities
Current regulatory liabilities	157	164
Unrealized gains/losses on commodity derivatives
Regulatory Assets and Liabilities
Non-current regulatory liabilities	4	2
Fuel cost adjustment receivable/liability
Regulatory Assets and Liabilities
Current regulatory liabilities	25	0
Deferred nuclear generating units
Regulatory Assets and Liabilities
Current regulatory assets	237	237
Non-current regulatory assets	1,004	1,042
Unrealized gains/losses on commodity derivatives
Regulatory Assets and Liabilities
Current regulatory assets	169	162
Non-current regulatory assets	81	63
Environmental agreements
Regulatory Assets and Liabilities
Current regulatory assets	49	47
Non-current regulatory assets	41	55
Environmental cleanup costs - Kingston ash spill
Regulatory Assets and Liabilities
Current regulatory assets	43	43
Non-current regulatory assets	331	348
Fuel cost adjustment receivable/liability
Regulatory Assets and Liabilities
Current regulatory assets	3	15
Other current regulatory assets
Regulatory Assets and Liabilities
Current regulatory assets	2	2
Deferred pension costs and other post-retirement benefits costs
Regulatory Assets and Liabilities
Non-current regulatory assets	5,556	5,565
Unrealized losses on interest rate derivatives
Regulatory Assets and Liabilities
Non-current regulatory assets	1,147	1,236
Nuclear decommissioning costs
Regulatory Assets and Liabilities
Non-current regulatory assets	970	1,003
Non-nuclear decommissioning costs
Regulatory Assets and Liabilities
Non-current regulatory assets	835	828
Other non-current regulatory assets
Regulatory Assets and Liabilities
Non-current regulatory assets	$ 272	$ 278

Variable Interest Entities Vari

Variable Interest Entities Variable Interest Entities (Details) - USD ($) $ in Millions	Dec. 31, 2015	Sep. 30, 2015	Sep. 30, 2013	Sep. 30, 2012
VIE Financing
Face amount			$ 40
Membership interests of VIE subject to mandatory redemption	$ 46	$ 47	$ 40
Liabilities
Total liabilities of VIE	1,330	1,315		$ 1,000
Long-term debt of VIE, net	1,233	1,233
Financial instruments subject to mandatory redemption, interest rate, stated percentage			7.00%
SCCG
VIE Financing
Face amount			$ 360
JSCCG
VIE Financing
Face amount				900
Holdco
VIE Financing
Face amount				100
Issuance of membership interests				$ 100
Accrued interest of VIE
Liabilities
Total liabilities of VIE	27	12
Current portion of membership interests of VIE subject to mandatory redemption
Liabilities
Total liabilities of VIE	2	2
Current maturities of long-term debt of VIE
Liabilities
Total liabilities of VIE	33	33
Total current liabilities of VIE
Liabilities
Total liabilities of VIE	62	47
Membership interests of VIE subject to mandatory redemption
Liabilities
Total liabilities of VIE	$ 35	$ 35

Other Long-Term Liabilities (De

Other Long-Term Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2015		Sep. 30, 2015
Other Long-Term Liabilities
Interest rate swap liabilities	$ 1,538		$ 1,627
EnergyRight® financing obligation	205		208
Currency swap liabilities	58	[1]	47	[2]
Total other long-term liabilities	2,149		2,219
Other Noncurrent Liabilities
Other Long-Term Liabilities
Interest rate swap liabilities	1,538		1,627
EnergyRight® financing obligation	146		148
Environmental agreements liability	41		55
Currency swap liabilities	58		47
Membership interests of VIE subject to mandatory redemption	35		35
Commodity contract derivative liabilities	46		17
Commodity swap derivative liabilities	9		10
Other	276		280
Accounts payable and accrued liabilities
Other Long-Term Liabilities
EnergyRight® financing obligation	$ 37		$ 37
[1]	Due to the right of setoff and method of settlement, TVA elects to record commodity derivatives under the FTP based on its net commodity position with the counterparty or FCM. Deposits are made to TVA's margin cash accounts held with each FCM to offset any net liability positions in full for derivatives that are transacted with FCMs. TVA records currency swaps net of cash collateral received from or paid to the counterparty, to the extent such amount is not recorded in Accounts payable and accrued liabilities. See Note 12 — Offsetting of Derivative Assets and Liabilities.
[2]	Due to the right of setoff and method of settlement, TVA elects to record commodity derivatives under the FTP based on its net commodity position with the counterparty or FCM. Deposits are made to TVA's margin cash accounts held with each FCM to offset any net liability positions in full for derivatives that are transacted with FCMs. TVA records currency swaps net of cash collateral received from or paid to the counterparty, to the extent such amount is not recorded in Accounts payable and accrued liabilities. See Note 12 — Offsetting of Derivative Assets and Liabilities.

Debt and Other Obligations Debt

Debt and Other Obligations Debt Outstanding (Details) - USD ($) $ in Millions		3 Months Ended	12 Months Ended
		Dec. 31, 2015	Sep. 30, 2015
Short-term debt
Short-term debt, net		$ 1,504	$ 1,034
Current maturities of long-term debt of variable interest entities		33	33
Current maturities of power bonds		554	32
Total current debt outstanding, net		2,091	1,099
Long-term debt
Long-term debt of variable interest entities		1,246	1,246
Long-term power bonds	[1]	22,242	22,792
Unamortized discounts, premiums, issue costs, and other		(184)	(188)
Total long-term debt, net		23,304	23,850
Total outstanding debt		25,395	24,949
Foreign Currency Transaction Gain (Loss), before Tax		$ 44	$ 21
[1]	Includes net exchange gain from currency transactions of $44 million at December 31, 2015 and $21 million at September 30, 2015.

Asset Retirement Obligations (D

Asset Retirement Obligations (Details) $ in Millions	3 Months Ended
	Dec. 31, 2015USD ($)
Asset Retirement Obligations
Asset retirement obligations, period increase (decrease)	$ (8)
Decommissioning study update - ARO nuclear	5 years
Accretion expense	$ 36
Balance at September 30, 2015	3,843	[1]
Settlements	(22)	[1]
Asset Retirement Obligation, Revision of Estimate	(7)	[1]
Accretion (recorded as regulatory asset)	37	[1]
Balance at December 31, 2015	3,851	[1]
Current portion of ARO	183
Nuclear
Asset Retirement Obligations
Balance at September 30, 2015	2,187	[1]
Settlements	0	[1]
Asset Retirement Obligation, Revision of Estimate	0	[1]
Accretion (recorded as regulatory asset)	26	[1]
Balance at December 31, 2015	2,213	[1]
Non-nuclear
Asset Retirement Obligations
Balance at September 30, 2015	1,656	[1]
Settlements	(22)	[1]
Asset Retirement Obligation, Revision of Estimate	(7)	[1]
Accretion (recorded as regulatory asset)	11	[1]
Balance at December 31, 2015	$ 1,638	[1]
[1]	The current portion of ARO in the amount of $183 million is included in Accounts payable and accrued liabilities at December 31, 2015.

Debt and Other Obligations De48

Debt and Other Obligations Debt Securities Activity (Details) - USD ($) $ in Millions	1 Months Ended		3 Months Ended
	Dec. 31, 2015	Nov. 30, 2015	Dec. 31, 2015	Dec. 31, 2014
Debt Instrument
Redemptions/maturities of power bonds			$ 4	$ 4
Total redemptions/maturities of debt			4
electronotes
Debt Instrument
Redemptions/maturities of power bonds			$ 1
Interest rate	2.65%		2.65%
2009 Series A
Debt Instrument
Redemptions/maturities of power bonds		$ 2
Interest rate		2.25%
2009 Series B
Debt Instrument
Redemptions/maturities of power bonds	$ 1
Interest rate	3.77%		3.77%
Total
Debt Instrument
Percent of par value	100.00%		100.00%

Debt and Other Obligations Cred

Debt and Other Obligations Credit Facility Agreements (Details) $ in Millions	Dec. 31, 2015USD ($)Credit_facilities	Sep. 30, 2015USD ($)
Line of Credit
Credit Facility Agreements
Current borrowing capacity for credit facilities	$ 150
Total Cash Borrowings for Credit Facilities	$ 0
Revolving Credit Facilities
Credit Facility Agreements
Number of revolving credit facilities | Credit_facilities	3
February 2020 Credit Facility	$ 500
June 2020 Credit Facility	1,000
September 2020 Credit Facility	1,000
Current borrowing capacity for credit facilities	2,500
Letter of Credit Outstanding, September 2020 Credit Facility	300
Cash Borrowings-February 2020 Credit Facility	0
Cash Borrowings-June 2020 Credit Facility	0
Cash Borrowings-September 2020 Credit Facility	0
Total Cash Borrowings for Credit Facilities	0	$ 0
Remaining Availability, February 2020 Credit Facility	0
Remaining Availability, June 2020 Credit Facility	700
Remaining Availability, September 2020 Credit Facility	700
Total Remaining Availability for Credit Facilities	1,400
Letter of Credit
Credit Facility Agreements
Letter of Credit Outstanding, February 2020 Credit Facility	500
Letter of Credit Outstanding, June 2020 Credit Facility	300
Amount of letters of credit outstanding for credit facilities	$ 1,100	$ 1,100

Debt and Other Obligations Leas

Debt and Other Obligations Lease/Leaseback Obligations (Details) $ in Millions	12 Months Ended
	Sep. 30, 2003USD ($)Units	Dec. 31, 2015USD ($)
Debt Disclosure [Abstract]
Proceeds prior to 2004	$ 945
Leaseback transaction, number of units | Units	24
Proceeds in 2003	$ 389
CT and QTE outstanding leaseback obligation		$ 616

Accumulated Other Comprehensi51

Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions		3 Months Ended
		Dec. 31, 2015	Dec. 31, 2014
Equity [Abstract]
Reclassification to earnings from cash flow hedges	[1]	$ 24	$ 38
[1]	There were no ineffective portions or amounts excluded from effectiveness testing for any of the periods presented. Based on forecasted foreign currency exchange rates, TVA expects to reclassify approximately $44 million of losses from AOCI to interest expense within the next twelve months to offset amounts anticipated to be recorded in interest expense related to exchange gain on the debt.

Risk Management Activities an52

Risk Management Activities and Derivative Transactions Derivative Instruments That Receive Hedge Accounting Treatment (Details) - USD ($)		3 Months Ended
		Dec. 31, 2015	Dec. 31, 2014
Summary of Derivative Instruments That Receive Hedge Accounting Treatment
Net unrealized gain (loss) on cash flow hedges		$ (27,000,000)	$ (15,000,000)
Reclassification to earnings from cash flow hedges	[1]	(24,000,000)	(38,000,000)
Ineffective portion excluded from testing		0	$ 0
Reclassification to earnings from cash flow hedges in the next 12 months		$ 44,000,000
Reclassification to earnings from cash flow hedges estimated time to transfer		12 months
[1]	There were no ineffective portions or amounts excluded from effectiveness testing for any of the periods presented. Based on forecasted foreign currency exchange rates, TVA expects to reclassify approximately $44 million of losses from AOCI to interest expense within the next twelve months to offset amounts anticipated to be recorded in interest expense related to exchange gain on the debt.

Risk Management Activities an53

Risk Management Activities and Derivative Transactions Derivative Instruments That Do Not Receive Hedge Accounting Treatment (Details)		3 Months Ended
		Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)	Sep. 30, 2015USD ($)
Derivative
Unrealized gain (loss) on derivatives		$ 0	$ 0
Change in Unrealized gains (losses) on Interest Rate Derivatives		89,000,000	(184,000,000)
Interest Rate Swap
Derivative
Amount of gain (loss) recognized in income on derivatives	[1]	(28,000,000)	(29,000,000)
Commodity Contract Derivatives
Derivative
Amount of gain (loss) recognized in income on derivatives	[1]	0	0
Fair value		(138,000,000)		$ (97,000,000)
Commodity derivatives under the financial trading program
Derivative
Amount of gain (loss) recognized in income on derivatives	[1]	(36,000,000)	$ (14,000,000)
Fair value	[2]	$ (101,000,000)		$ (116,000,000)
Coal Contract Derivatives
Derivative
Number of contracts		12		14
Notional amount		20,000,000		19,000,000
Fair value		$ (123,000,000)		$ (98,000,000)
Natural Gas
Derivative
Number of contracts		30		33
Notional amount		132,000,000		134,000,000
Fair value		$ (15,000,000)		$ 1,000,000
Maximum | Coal Contract Derivatives
Derivative
Derivative, Term of Contract		3 years
Maximum | Natural Gas
Derivative
Derivative, Term of Contract		3 years
Natural Gas
Derivative
Fair value		$ (101,000,000)		$ (116,000,000)
[1]	All of TVA's derivative instruments that do not receive hedge accounting treatment have unrealized gains (losses) that would otherwise be recognized in incomebut instead are deferred as regulatory assets and liabilities. As such, there was no related gain (loss) recognized in income for these unrealized gains (losses) for the three months ended December 31, 2015 and 2014.
[2]	Fair values of certain derivatives under the FTP that were in net liability positions totaling $80 million and $89 million at December 31, 2015 and September 30, 2015, respectively, are recorded in TVA's margin cash accounts in Other current assets. These derivatives are transacted with futures commission merchants, and cash deposits have been posted to the margin cash accounts held with each futures commission merchant to offset the net liability positions in full.

Risk Management Activities an54

Risk Management Activities and Derivative Transactions Fair Values of TVA Derivatives (Details) - USD ($) $ in Millions		Dec. 31, 2015	Sep. 30, 2015
Derivatives, Fair Value
Gross amounts of recognized liabilities		$ 1,733	$ 1,839
200 million Sterling currency swap | Other long-term liabilities
Derivatives, Fair Value
Fair value		(43)	(41)
250 million Sterling currency swap | Other long-term assets
Derivatives, Fair Value
Fair value		9	25
150 million Sterling currency swap | Other long-term liabilities
Derivatives, Fair Value
Fair value		(15)	(6)
$1.0 billion notional interest rate swap | Other long-term liabilities
Derivatives, Fair Value
Fair value		(1,115)	(1,177)
$476 million notional interest rate swap | Other long-term liabilities
Derivatives, Fair Value
Fair value		(412)	(438)
$42 million notional interest rate swap | Other long-term liabilities
Derivatives, Fair Value
Fair value		(11)	(12)
Commodity contract derivatives
Derivatives, Fair Value
Fair value		(138)	(97)
Commodity contract derivatives | Other long-term assets
Derivatives, Fair Value
Fair value		4	1
Commodity contract derivatives | Other long-term liabilities
Derivatives, Fair Value
Fair value		(46)	(17)
Commodity contract derivatives | Accounts payable and accrued liabilities
Derivatives, Fair Value
Fair value		(96)	(81)
Commodity derivatives under FTP
Derivatives, Fair Value
Fair value	[1]	(101)	(116)
Commodity derivatives under FTP | Other current assets
Derivatives, Fair Value
Gross amounts of recognized liabilities		80	89
Fair value		(80)	(89)
Commodity derivatives under FTP | Other long-term liabilities
Derivatives, Fair Value
Fair value		(9)	(10)
Commodity derivatives under FTP | Accounts payable and accrued liabilities
Derivatives, Fair Value
Fair value		$ (12)	$ (17)
[1]	Fair values of certain derivatives under the FTP that were in net liability positions totaling $80 million and $89 million at December 31, 2015 and September 30, 2015, respectively, are recorded in TVA's margin cash accounts in Other current assets. These derivatives are transacted with futures commission merchants, and cash deposits have been posted to the margin cash accounts held with each futures commission merchant to offset the net liability positions in full.

Risk Management Activities an55

Risk Management Activities and Derivative Transactions Currency Swaps Outstanding (Details) £ in Millions	3 Months Ended
	Dec. 31, 2015GBP (£)
1999 Currency Swap Contract
Derivative
Effective Date of Currency Swap Contract	1,999
Associated TVA bond issues currency exposure	£ 200
Expiration Date of Swap	2,021
Overall effective cost to TVA	5.81%
2001 Currency Swap Contract
Derivative
Effective Date of Currency Swap Contract	2,001
Associated TVA bond issues currency exposure	£ 250
Expiration Date of Swap	2,032
Overall effective cost to TVA	6.59%
2003 Currency Swap Contract
Derivative
Effective Date of Currency Swap Contract	2,003
Associated TVA bond issues currency exposure	£ 150
Expiration Date of Swap	2,043
Overall effective cost to TVA	4.96%

Risk Management Activities an56

Risk Management Activities and Derivative Transactions Derivatives Under FTP (Details) $ in Millions		3 Months Ended
		Dec. 31, 2015USD ($)	Sep. 30, 2015USD ($)
Derivative
FTP transaction limit		$ 130
Maximum hedge volume		75.00%
Market value limitation of outstanding construction materials hedging transactions		$ 100
Portfolio value at risk limit for foreign currency transactions		$ 5
Natural Gas
Derivative
Notional amount		132,000,000	134,000,000
Fair value		$ (15)	$ 1
Number of Price Risk Derivatives Held		30	33
Coal Contract
Derivative
Notional amount		20,000,000	19,000,000
Fair value		$ (123)	$ (98)
Number of Price Risk Derivatives Held		12	14
Swap contracts
Derivative
Remaining terms		2
Natural Gas Swap
Derivative
Notional amount	[1]	40,977,500	51,495,000
Fair value	[1]	$ (101)	$ (116)
Maximum | Natural Gas
Derivative
Derivative, Term of Contract		3 years
Maximum | Coal Contract
Derivative
Derivative, Term of Contract		3 years
[1]	Fair value amounts presented are based on the net commodity position with the counterparty. Notional amounts disclosed represent the net absolute value of contractual amounts.

Risk Management Activities an57

Risk Management Activities and Derivative Transactions Derivatives Under Financial Trading Program (Details) - USD ($) $ in Millions		3 Months Ended
		Dec. 31, 2015	Dec. 31, 2014	Sep. 30, 2015
Natural Gas Swap
Derivative
Fair value	[1]	$ (101)		$ (116)
Natural Gas Total Contracts
Derivative
Fair value		(101)		(116)
Decrease (increase) in fuel expense		(29)	$ (12)
Decrease (increase) in purchased power expense		(7)	(3)
Fuel Oil and Crude Oil Total Contracts
Derivative
Decrease (increase) in fuel expense		0	$ 1
Closed derivative contracts
Derivative
Fair value		$ (6)		$ (11)
[1]	Fair value amounts presented are based on the net commodity position with the counterparty. Notional amounts disclosed represent the net absolute value of contractual amounts.

Risk Management Activities an58

Risk Management Activities and Derivative Transactions Offsetting of Derivative Assets (Details) - USD ($) $ in Millions		Dec. 31, 2015	Sep. 30, 2015
Offsetting Assets [Line Items]
Gross Amounts of Recognized Assets		$ 45	$ 74
Gross Amounts Offset in the Balance Sheet	[1]	(36)	(49)
Net Amounts of Assets Presented in the Balance Sheet	[2]	13	26
Total derivatives not subject to master netting or similar arrangement	[2]	4	1
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement		49	75
Currency Swap [Member]
Offsetting Assets [Line Items]
Gross Amounts of Recognized Assets	[3],[4]	9	25
Gross Amounts Offset in the Balance Sheet	[1],[3],[4]	0	0
Net Amounts of Assets Presented in the Balance Sheet	[2],[3],[4]	9	25
Commodity derivatives under FTP
Offsetting Assets [Line Items]
Gross Amounts of Recognized Assets		36	49
Gross Amounts Offset in the Balance Sheet	[1]	(36)	(49)
Net Amounts of Assets Presented in the Balance Sheet	[2]	0	0
Total derivatives subject to master netting or similar arrangement [Member]
Offsetting Assets [Line Items]
Net Amounts of Assets Presented in the Balance Sheet	[2]	$ 9	$ 25
[1]	Amounts primarily include counterparty netting of derivative contracts, margin account deposits for futures commission merchants transactions, and cash collateral received or paid in accordance with the accounting guidance for derivatives and hedging transactions.
[2]	There are no derivative contracts subject to a master netting arrangement or similar agreement which are not offset in the balance sheets.
[3]	At December 31, 2015 and September 30, 2015, there were no securities posted by a counterparty on TVA's behalf to partially secure the asset position(s) of currency swaps in accordance with the collateral requirements for these derivatives.
[4]	Letters of credit of approximately $1.1 billion were posted as collateral at both December 31, 2015 and September 30, 2015, to partially secure the liability positions of one of the currency swaps and one of the interest rate swaps in accordance with the collateral requirements for these derivatives. TVA held $20 million and $15 million cash collateral in excess of collateral requirements at December 31, 2015 and September 30, 2015, respectively. Cash collateral held in excess of collateral requirements is recorded in Restricted cash and investments with a corresponding obligation of the same amount recorded in Accounts payable and accrued liabilities.

Risk Management Activities an59

Risk Management Activities and Derivative Transactions Offsetting for Derivative Liabilities (Details) - USD ($) $ in Millions		Dec. 31, 2015	Sep. 30, 2015
Offsetting Liabilities [Line Items]
Securities Borrowed		$ 0	$ 0
Cash Collateral in Excess of Collateral Requirements		20	15
Forward Contract Derivative Liability, at Fair Value		8	59
Gross amounts of recognized liabilities		1,733	1,839
Gross Amounts Offset in the Balance Sheet	[1]	(116)	(138)
Net Amounts of Liabilities Presented in the Balance Sheet	[2]	1,759	1,799
Total derivatives not subject to master netting or similar arrangement	[2]	142	98
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement		1,875	1,937
Currency Swap [Member]
Offsetting Liabilities [Line Items]
Gross amounts of recognized liabilities	[3]	58	47
Gross Amounts Offset in the Balance Sheet	[1],[3]	0	0
Net Amounts of Liabilities Presented in the Balance Sheet	[2],[3]	58	47
Interest Rate Contract [Member]
Offsetting Liabilities [Line Items]
Gross amounts of recognized liabilities	[3]	1,538	1,627
Gross Amounts Offset in the Balance Sheet	[1],[3]	0	0
Net Amounts of Liabilities Presented in the Balance Sheet	[2],[3]	1,538	1,627
Commodity derivatives under FTP
Offsetting Liabilities [Line Items]
Gross amounts of recognized liabilities		137	165
Gross Amounts Offset in the Balance Sheet	[1]	(116)	(138)
Net Amounts of Liabilities Presented in the Balance Sheet	[2]	21	27
Total derivatives subject to master netting or similar arrangement [Member]
Offsetting Liabilities [Line Items]
Net Amounts of Liabilities Presented in the Balance Sheet	[2]	1,617	1,701
Fair Value, Inputs, Level 2
Offsetting Liabilities [Line Items]
Forward Contract Derivative Liability, at Fair Value		8	59
Letter of Credit
Offsetting Liabilities [Line Items]
Amount of letters of credit outstanding		$ 1,100	$ 1,100
[1]	Amounts primarily include counterparty netting of derivative contracts, margin account deposits for futures commission merchants transactions, and cash collateral received or paid in accordance with the accounting guidance for derivatives and hedging transactions.
[2]	There are no derivative contracts subject to a master netting arrangement or similar agreement which are not offset in the balance sheets.
[3]	Letters of credit of approximately $1.1 billion were posted as collateral at both December 31, 2015 and September 30, 2015, to partially secure the liability positions of one of the currency swaps and one of the interest rate swaps in accordance with the collateral requirements for these derivatives. TVA held $20 million and $15 million cash collateral in excess of collateral requirements at December 31, 2015 and September 30, 2015, respectively. Cash collateral held in excess of collateral requirements is recorded in Restricted cash and investments with a corresponding obligation of the same amount recorded in Accounts payable and accrued liabilities.

Risk Management Activities an60

Risk Management Activities and Derivative Transactions Collateral (Details) $ in Millions	Dec. 31, 2015USD ($)
Derivative
Likely cash collateral obligation increase	$ 22
Collateral
Derivative
Derivative, net liability position, aggregate fair value	1,600
Collateral obligations	1,100
Collateral already posted	$ 1,100

Risk Management Activities an61

Risk Management Activities and Derivative Transactions Counterparty Credit Risk (Details)	3 Months Ended
	Dec. 31, 2015merchantsCustomersmegawatts	Dec. 31, 2014Customers	Sep. 30, 2015Customers
Derivative
Number of active future commission merchants | merchants	2
Credit of Customers
Derivative
Number of customers that represent the percent of sales	6	6
Number of customers that represent the concentration of accounts receivable percent outstanding			3
Sales Concentration	32.00%	32.00%
Percent of total outstanding accounts receivables			27.00%
Megawatts of Power Purchase Agreement
Derivative
Megawatts of Power Purchase Agreement | megawatts	440

Fair Value Measurements Investm

Fair Value Measurements Investments Gains (Losses) (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Investment Gains (Losses)
Securities classified as trading and measured at fair value	$ 2,100
NDT unfunded commitments related to private partnerships	79
Nuclear Decommissioning Fund Investments, Fair Value	1,500
Decommissioning Fund Investments, Fair Value	449
SERP
Investment Gains (Losses)
Unrealized gains (losses) on investments	0	$ (1)
LTDCP
Investment Gains (Losses)
Unrealized gains (losses) on investments	0	(1)
NDT
Investment Gains (Losses)
Unrealized gains (losses) on investments	39	23
ART
Investment Gains (Losses)
Unrealized gains (losses) on investments	12	$ 6
Maximum
Investment Gains (Losses)
Derivative Credit Risk Valuation Adjustment, Derivative Assets	1
Equity investments not required to be measured at fair value	$ 1

Fair Value Measurements Nonperf

Fair Value Measurements Nonperformance Risk (Details) $ in Millions	Dec. 31, 2015USD ($)
Nonperformance Risk
Derivative credit valuation adjustment, liabilities	$ 1

Fair Value Measurements Fair Va

Fair Value Measurements Fair Value Measurements (Details) - USD ($) $ in Millions	Dec. 31, 2015		Sep. 30, 2015
Investments
Equity securities	$ 185		$ 166
Debt Instruments
U.S. government corporations and agencies	239		234
Corporate debt securities	254		225
Residential mortgage-backed securities	16		17
Commercial mortgage-backed securities	5		7
Collateralized debt obligations	28		29
Institutional mutual funds	88		91
Forward debt securities contracts	(8)		(59)
Private partnerships measured at net asset value	245	[1]	240	[2]
Commingled funds measured at net asset value	1,031	[1]	1,061	[2]
Total investments	2,083		2,011
Currency swap(s)	9	[3]	25	[4]
Commodity contract derivatives	4		1
Commodity derivatives under FTP
Swap contracts	0	[3]	0	[4]
Total	2,096		2,037
Liabilities
Currency swap(s)	58	[3]	47	[4]
Interest rate swaps	1,538		1,627
Commodity contract derivatives	142		98
Commodity derivatives under FTP
Swap contracts	21	[3]	27	[4]
Total	1,759		1,799
Fair Value, Inputs, Level 1
Investments
Equity securities	185		166
Debt Instruments
U.S. government corporations and agencies	200		203
Corporate debt securities	0		0
Residential mortgage-backed securities	0		0
Commercial mortgage-backed securities	0		0
Collateralized debt obligations	0		0
Institutional mutual funds	88		91
Forward debt securities contracts	0		0
Private partnerships measured at net asset value	0	[1]	0	[2]
Commingled funds measured at net asset value	0	[1]	0	[2]
Total investments	473		460
Currency swap(s)	0	[3]	0	[4]
Commodity contract derivatives	0		0
Commodity derivatives under FTP
Swap contracts	0	[3]	0	[4]
Total	473		460
Liabilities
Currency swap(s)	0	[3]	0	[4]
Interest rate swaps	0		0
Commodity contract derivatives	0		0
Commodity derivatives under FTP
Swap contracts	0	[3]	0	[4]
Total	0		0
Fair Value, Inputs, Level 2
Investments
Equity securities	0		0
Debt Instruments
U.S. government corporations and agencies	39		31
Corporate debt securities	254		225
Residential mortgage-backed securities	16		17
Commercial mortgage-backed securities	5		7
Collateralized debt obligations	28		29
Institutional mutual funds	0		0
Forward debt securities contracts	(8)		(59)
Private partnerships measured at net asset value	0	[1]	0	[2]
Commingled funds measured at net asset value	0	[1]	0	[2]
Total investments	334		250
Currency swap(s)	9	[3]	25	[4]
Commodity contract derivatives	4		1
Commodity derivatives under FTP
Swap contracts	0	[3]	0	[4]
Total	347		276
Liabilities
Currency swap(s)	58	[3]	47	[4]
Interest rate swaps	1,538		1,627
Commodity contract derivatives	19		0
Commodity derivatives under FTP
Swap contracts	21	[3]	27	[4]
Total	1,636		1,701
Fair Value, Inputs, Level 3
Investments
Equity securities	0		0
Debt Instruments
U.S. government corporations and agencies	0		0
Corporate debt securities	0		0
Residential mortgage-backed securities	0		0
Commercial mortgage-backed securities	0		0
Collateralized debt obligations	0		0
Institutional mutual funds	0		0
Forward debt securities contracts	0		0
Private partnerships measured at net asset value	0	[1]	0	[2]
Commingled funds measured at net asset value	0	[1]	0	[2]
Total investments	0		0
Currency swap(s)	0	[3]	0	[4]
Commodity contract derivatives	0		0
Commodity derivatives under FTP
Swap contracts	0	[3]	0	[4]
Total	0		0
Liabilities
Currency swap(s)	0	[3]	0	[4]
Interest rate swaps	0		0
Commodity contract derivatives	123		98
Commodity derivatives under FTP
Swap contracts	0	[3]	0	[4]
Total	$ 123		$ 98
[1]	Certain investments that are measured at fair value using the net asset value 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 in the consolidated balance sheets.
[2]	Certain investments that are measured at fair value using the net asset value 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 in the consolidated balance sheets.
[3]	Due to the right of setoff and method of settlement, TVA elects to record commodity derivatives under the FTP based on its net commodity position with the counterparty or FCM. Deposits are made to TVA's margin cash accounts held with each FCM to offset any net liability positions in full for derivatives that are transacted with FCMs. TVA records currency swaps net of cash collateral received from or paid to the counterparty, to the extent such amount is not recorded in Accounts payable and accrued liabilities. See Note 12 — Offsetting of Derivative Assets and Liabilities.
[4]	Due to the right of setoff and method of settlement, TVA elects to record commodity derivatives under the FTP based on its net commodity position with the counterparty or FCM. Deposits are made to TVA's margin cash accounts held with each FCM to offset any net liability positions in full for derivatives that are transacted with FCMs. TVA records currency swaps net of cash collateral received from or paid to the counterparty, to the extent such amount is not recorded in Accounts payable and accrued liabilities. See Note 12 — Offsetting of Derivative Assets and Liabilities.

Fair Value Measurements Fair 65

Fair Value Measurements Fair Value Measurements Using Significant Unobservable Inputs (Details) tons-per-year in Billions	3 Months Ended
	Dec. 31, 2015USD ($)tons-per-year	Dec. 31, 2014USD ($)	Sep. 30, 2015USD ($)tons-per-year	Sep. 30, 2014USD ($)
ASSETS
Commodity contract derivatives	$ 4,000,000		$ 1,000,000
Liabilities
Commodity contract derivatives	$ 142,000,000		$ 98,000,000
Maximum
ASSETS
Fair value measurements tons per year | tons-per-year	1		1
Price per ton	$ 121.51		$ 103.41
Liabilities
Fair value measurements tons per year | tons-per-year	1		1
Price per ton	$ 121.51		$ 103.41
Minimum
ASSETS
Fair value measurements tons per year | tons-per-year	0.8		0.8
Price per ton	$ 9.83		$ 10.64
Liabilities
Fair value measurements tons per year | tons-per-year	0.8		0.8
Price per ton	$ 9.83		$ 10.64
Fair Value, Inputs, Level 3
ASSETS
Commodity contract derivatives	0		0
Liabilities
Commodity contract derivatives	123,000,000		98,000,000
Commodity Contract Derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Balance	(123,000,000)	$ (107,000,000)	$ (98,000,000)	$ (85,000,000)
Purchases	0	0
Issuances	0	0
Sales	0	0
Settlements	0	0
Net unrealized gains (losses) deferred as regulatory assets and liabilities	$ (25,000,000)	$ (22,000,000)

Fair Value Measurements Estimat

Fair Value Measurements Estimated Values of Financial Instruments Not Recorded at Fair Value (Details) - USD ($) $ in Millions	Dec. 31, 2015	Sep. 30, 2015	Sep. 30, 2013
Estimated Values of Financial Intruments Not Recorded at Fair Value
EnergyRight receivables (including current portion)	$ 161	$ 162
Loans and other long-term receivables, net (including current portion)	124	117
EnergyRight® financing obligation (including current portion)	205	208
Unfunded Loan Commitments	11	9
Membership interest of variable interest entity subject to mandatory redemption (including current portion)	46	47	$ 40
Long-term outstanding power bonds (including current maturities), net	26,155	25,468
Long-term debt of variable interest entities (including current maturities), net	1,388	1,407
Carrying Value
Estimated Values of Financial Intruments Not Recorded at Fair Value
EnergyRight receivables (including current portion)	155	156
Loans and other long-term receivables, net (including current portion)	135	129
EnergyRight® financing obligation (including current portion)	183	185
Unfunded Loan Commitments	0	0
Membership interest of variable interest entity subject to mandatory redemption (including current portion)	37	37
Long-term outstanding power bonds (including current maturities), net	22,625	22,649
Long-term debt of variable interest entities (including current maturities), net	$ 1,266	$ 1,266

Other Income (Expense), Net (De

Other Income (Expense), Net (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Other Income (Expense), Net
Interest income	$ 6	$ 6
External services	4	3
Gains (losses) on investments	3	1
Miscellaneous	(1)	(1)
Total other income (expense), net	$ 12	$ 9

Benefit Plans Components of Ben

Benefit Plans Components of Benefit Plans (Details)	3 Months Ended
	Dec. 31, 2015plans
Defined Benefit Plan Disclosure
Number of defined benefit plans	1
Number of defined contribution plans	1
Number of unfunded post-retirement health care plans	2

Benefit Plans Components of Net

Benefit Plans Components of Net Periodic Benefit Cost (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Pension Benefits
Defined Benefit Plan Disclosure
Service cost	$ 32	$ 34
Interest cost	140	133
Expected return on plan assets	(111)	(109)
Amortization of prior service cost	(6)	(5)
Recognized net actuarial loss	73	69
Total net periodic benefit cost as actuarially determined	128	122
Amount capitalized due to actions of regulator	(58)	(51)
Total net periodic benefit cost	70	71
Other Post-retirement Benefits
Defined Benefit Plan Disclosure
Service cost	4	5
Interest cost	7	8
Expected return on plan assets	0	0
Amortization of prior service cost	(1)	(2)
Recognized net actuarial loss	2	2
Total net periodic benefit cost as actuarially determined	12	13
Amount capitalized due to actions of regulator	0	0
Total net periodic benefit cost	$ 12	$ 13

Benefit Plans Contributions (De

Benefit Plans Contributions (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Sep. 30, 2016	Sep. 30, 2015
Other Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure
Defined Benefit Plan, Contributions by Employer				$ 275
Other Post-retirement Benefits
Defined Benefit Plan Disclosure
Defined Benefit Plan, Contributions by Employer	$ 17	$ 16
Scenario, Forecast | Other Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure
Defined Benefit Plan, Contributions by Employer			$ 275

Contingencies and Legal Proce71

Contingencies and Legal Proceedings Contingencies (Details) $ in Thousands	3 Months Ended
	Dec. 31, 2015USD ($)UnitsreactorsInsurance_layersProceduresSites
Loss Contingencies
Nuclear liability insurance	$ 375,000
Number of sites | Sites	1
Assessment from licensees for each licensed reactor	$ 127,000
Number of licensed reactors in US | reactors	103
Nuclear accident assessment limitation per year per unit	$ 19,000
Number of licensed nuclear units | Units	7
Maximum assessment per nuclear incident	$ 891,000
Maximum payment required per incident in any one year	133,000
Total amount of protection available	$ 13,000,000
Surcharge for legal expenses	5.00%
Number of layers before Congress is required to take action | Insurance_layers	2
Amount of property, decommissioning, and decontamination insurance carried	$ 5,100,000
Amount of insurance available for loss at any one site	2,100,000
Maximum amount of retrospecitve premiums	127,000
Maximum indemnity if a covered accident takes or keeps a nuclear unit offline	490,000
Maximum retrospective premiums	$ 36,000
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	$ 650,000
Amount of settlement for potential liability related to soil cleanup	300
Amount of settlement for potential liability related to EPA study of site	8
Remaining cleanup, remediation, and natural resource damages are less than	1,000
Accrual for Environmental Loss Contingencies, Gross	23,000
Non-nuclear | Non-nuclear
Loss Contingencies
Present value of estimated future decommissioning cost	1,600,000
Nuclear | Nuclear
Loss Contingencies
Present value of estimated future decommissioning cost	$ 2,200,000

Contingencies and Legal Proce72

Contingencies and Legal Proceedings Legal Proceedings (Details)	1 Months Ended						3 Months Ended	12 Months Ended
	Jul. 31, 2013Legal_actions	May. 31, 2013	Apr. 30, 2011GroupsAgreements	Mar. 31, 2010USD ($)People	Jun. 30, 2008Legal_actions	Oct. 31, 2007Legal_actions	Dec. 31, 2015USD ($)	Dec. 31, 2010Years	Jun. 30, 2011USD ($)Unitsmegawatts
Legal Proceedings
Possible additional future costs for compliance with Clean Air Act requirements							$ 650,000,000
TDEC civil penalties related to Gallatin							17,000
Plaintiff civil penalties related to Gallatin							$ 37,500
Units Affected by Paradise Case							2
Number of claims dismissed related to NPDES permit							7
Number of claims filed on Gallatin NPDES permit							8
Number of reactors a CCOLA was submitted for | Legal_actions						2
General
Legal Proceedings
Legal loss contingency accrual							$ 99,000,000
Environmental Agreements
Legal Proceedings
Number of similar environmental agreements entered into | Agreements			2
Number of environmental agreements entered into with the EPA | Agreements			1
Number of environmental agreements entered into with Alabama, Kentucky, North Carolina, and Tennessee | Agreements			1
Number of environmental agreements entered into with environmental advocacy groups | Groups			3
Number of units to be idled | Units									18
Megawatts | megawatts									2,200
Megawatts option 2									3,500
Amount to be invested in certain TVA environmental projects									$ 290,000,000
Amount to be provided to fund environmental projects									60,000,000
Amount to pay civil penalties									$ 10,000,000
Case Involving Tennessee Valley Authority Retirement System
Legal Proceedings
Number of participants that filed suit | People				8
Pension and Other Postretirement Benefit Contributions				$ 1,000,000,000
Retirement age of eligibility for cost of living adjustment before January 1, 2010 | Years								55
Retirement age of eligibility for cost of living adjustment after January 1, 2010 | Years								60
Administrative Proceedings Regarding Sequoyah U1 and U2 [Member]
Legal Proceedings
Number of contentions submitted by BREDL BEST and MATRR		8
Opposed contentions		8
Number of petitioners with standing	1
Number of petitioners	3
Number of contentions dismissed | Legal_actions	7
Number of contentions left | Legal_actions	1
Administrative Proceedings Regarding Bellefonte Units 3 and 4
Legal Proceedings
Number of contentions left | Legal_actions					2
Number of admitted contentions submitted by BREDL and SACE | Legal_actions					4
Number of contentions submitted by BREDL and SACE | Legal_actions					20
Number of contentions no longer admitted | Legal_actions					2
Other Noncurrent Liabilities | General
Legal Proceedings
Legal loss contingency accrual							41,000,000
Accounts payable and accrued liabilities | General
Legal Proceedings
Legal loss contingency accrual							$ 58,000,000