Tennessee Valley Authority PARRS D 2028 (TVC) 10-Q 4 Aug 15 2015 Q3 Quarterly report Financial data

DEI Document

DEI Document - Jun. 30, 2015 - USD ($) shares in Millions, $ in Millions	Total
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	Jun. 30, 2015
Document Fiscal Year Focus	2,015
Document Fiscal Period Focus	Q3
Amendment Flag	false
Entity Common Stock, Shares Outstanding	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		9 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Operating revenues
Revenue from sales of electricity	$ 2,522	$ 2,618	$ 7,722	$ 7,869
Other revenue	36	33	110	102
Total operating revenues	2,558	2,651	7,832	7,971
Operating expenses
Fuel	608	698	1,744	1,904
Purchased power	244	279	736	843
Operating and maintenance	738	880	2,083	2,480
Depreciation and amortization	534	463	1,440	1,357
Tax equivalents	128	133	383	395
Total operating expenses	2,252	2,453	6,386	6,979
Operating income	306	198	1,446	992
Other income (expense), net	8	10	25	37
Interest expense
Interest expense	337	334	1,020	1,009
Allowance for funds used during construction	(55)	(45)	(158)	(127)
Net interest expense	282	289	862	882
Net income (loss)	$ 32	$ (81)	$ 609	$ 147

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (UNAUDITED) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Net income (loss)		$ 32	$ (81)	$ 609	$ 147
Other comprehensive income (loss)
Net unrealized gain (loss) on cash flow hedges		62	1	(12)	23
Reclassification to earnings from cash flow hedges	[1]	(53)	(26)	31	(55)
Total other comprehensive income (loss)		9	(25)	19	(32)
Total comprehensive income (loss)		$ 41	$ (106)	$ 628	$ 115
[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 $91 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	Jun. 30, 2015	Sep. 30, 2014
Current assets
Cash and cash equivalents	$ 500	$ 500
Restricted cash and investments	0	19
Accounts receivable, net	1,575	1,676
Inventories, net	1,126	1,056
Regulatory assets	549	481
Other current assets	81	56
Total current assets	3,831	3,788
Property, plant, and equipment
Completed plant	49,782	47,564
Less accumulated depreciation	(25,755)	(24,589)
Net completed plant	24,027	22,975
Construction in progress	6,640	5,951
Nuclear fuel	1,329	1,322
Capital leases	96	102
Total property, plant, and equipment, net	32,092	30,350
Investment funds	2,079	1,981
Regulatory and other long-term assets
Regulatory assets	8,787	8,994
Other long-term assets	531	483
Total regulatory and other long-term assets	9,318	9,477
Total assets	47,320	45,596
Current liabilities
Accounts payable and accrued liabilities	1,956	2,050
Accrued interest	315	380
Current portion of leaseback obligations	79	75
Current portion of energy prepayment obligations	100	100
Regulatory liabilities	168	184
Short-term debt, net	2,582	596
Current maturities of power bonds	32	1,032
Current maturities of long-term debt of variable interest entities	33	32
Total current liabilities	5,265	4,449
Other liabilities
Post-retirement and post-employment benefit obligations	5,852	5,839
Asset retirement obligations	3,676	3,089
Other long-term liabilities	2,019	1,962
Leaseback obligations	538	616
Energy prepayment obligations	235	310
Regulatory liabilities	1	0
Total other liabilities	12,321	11,816
Long-term debt, net
Long-term power bonds, net	21,744	21,948
Long-term debt of variable interest entities	1,263	1,279
Total long-term debt, net	23,007	23,227
Total liabilities	40,593	39,492
Proprietary capital
Power program appropriation investment	258	258
Power program retained earnings	5,852	5,240
Total power program proprietary capital	6,110	5,498
Nonpower programs appropriation investment, net	593	601
Accumulated other comprehensive income (loss)	24	5
Total proprietary capital	6,727	6,104
Total liabilities and proprietary capital	$ 47,320	$ 45,596

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED) - USD ($) $ in Millions	9 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Cash flows from operating activities
Net income (loss)	$ 609	$ 147
Adjustments to reconcile net income (loss) to net cash provided by operating activities
Depreciation and amortization (including amortization of debt issuance costs and premiums/discounts)	1,475	1,391
Amortization of nuclear fuel cost	206	205
Non-cash retirement benefit expense	249	429
Prepayment credits applied to revenue	(75)	(75)
Fuel cost adjustment deferral	(6)	(91)
Fuel cost tax equivalents	(17)	1
Changes in current assets and liabilities
Accounts receivable, net	118	15
Inventories and other, net	(117)	33
Accounts payable and accrued liabilities	(208)	22
Accrued interest	(65)	(66)
Regulatory assets costs	(18)	(49)
Pension contributions	(144)	(132)
Insurance recoveries	50	175
Other, net	(41)	(18)
Net cash provided by operating activities	2,016	1,987
Cash flows from investing activities
Construction expenditures	(2,064)	(1,694)
Combined cycle plant acquisition	(342)	0
Nuclear fuel expenditures	(252)	(272)
Purchases of investments	(1)	0
Loans and other receivables
Advances	(11)	(3)
Repayments	7	5
Other, net	(27)	3
Net cash used in investing activities	(2,690)	(1,961)
Long-term debt
Redemptions and repurchases of power bonds	(1,180)	(363)
Redemptions of variable interest entities	(15)	(15)
Short-term debt issues (redemptions), net	1,986	(674)
Payments on leases and leasebacks	(77)	(70)
Payments to U.S. Treasury	(5)	(10)
Other, net	(35)	9
Net cash provided by (used in) financing activities	674	(1,123)
Net change in cash and cash equivalents	0	(1,097)
Cash and cash equivalents at beginning of period	500	1,602
Cash and cash equivalents at end of period	500	505
Significant non-cash transactions
Accrued capital and nuclear fuel expenditures	$ 414	$ 242

CONSOLIDATED STATEMENTS OF CHAN

CONSOLIDATED STATEMENTS OF CHANGES IN PROPRIETARY CAPITAL (UNAUDITED) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Balance at Beginning of Period	$ 6,687	$ 5,861	$ 6,104	$ 5,647
Net income (loss)	32	(81)	609	147
Total other comprehensive income (loss)	9	(25)	19	(32)
Return on power program appropriation investment	(1)	(1)	(5)	(3)
Return of power program appropriation investment		(2)		(7)
Balance at End of Period	6,727	5,752	6,727	5,752
Power Program Appropriation Investment
Balance at Beginning of Period	258	263	258	268
Net income (loss)	0	0	0	0
Total other comprehensive income (loss)	0	0	0	0
Return on power program appropriation investment	0	0	0	0
Return of power program appropriation investment		(2)		(7)
Balance at End of Period	258	261	258	261
Power Program Retained Earnings
Balance at Beginning of Period	5,819	4,997	5,240	4,767
Net income (loss)	34	(79)	617	153
Total other comprehensive income (loss)	0	0	0	0
Return on power program appropriation investment	(1)	(1)	(5)	(3)
Return of power program appropriation investment		0		0
Balance at End of Period	5,852	4,917	5,852	4,917
Nonpower Programs Appropriation Investment, Net
Balance at Beginning of Period	595	605	601	609
Net income (loss)	(2)	(2)	(8)	(6)
Total other comprehensive income (loss)	0	0	0	0
Return on power program appropriation investment	0	0	0	0
Return of power program appropriation investment		0		0
Balance at End of Period	593	603	593	603
Accumulated Other Comprehensive Income (Loss) from Net Gains (Losses) on Cash Flow Hedges
Balance at Beginning of Period	15	(4)	5	3
Net income (loss)	0	0	0	0
Total other comprehensive income (loss)	9	(25)	19	(32)
Return on power program appropriation investment	0	0	0	0
Return of power program appropriation investment		0		0
Balance at End of Period	$ 24	$ (29)	$ 24	$ (29)

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
	Jun. 30, 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 ( 2015 , 2014 , 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, 2014 , and the notes thereto, which are contained in TVA's Annual Report on Form 10-K for the year ended September 30, 2014 (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 9 . 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 reclassifications have been made to the Consolidated Statement of Cash Flows for the nine months ended June 30, 2015 , in the Cash flows from operating activities section as $ 51 million previously reported as Environmental cleanup costs — Kingston ash spill — non cash and $ (65) million previously reported as Environmental cleanup costs — Kingston ash spill for the for the nine months ended June 30, 2014 , were reclassified to $ (14) million Other, net. 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 after 90 days . 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 June 30, 2015 and September 30, 2014 , for accounts receivable. Additionally, loans receivable of $ 111 million and $ 92 million at June 30, 2015 and September 30, 2014 , 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 $ 9 million at both June 30, 2015 and September 30, 2014 . Depreciation Depreciation expense was $ 462 million and $ 391 million for the three months ended June 30, 2015 , and 2014 , respectively, and $ 1.2 billion and $ 1.1 billion for the nine months ended June 30, 2015 , and 2014 , respectively. In May 2015, TVA's Board approved that Widows Creek Fossil Plant ("Widows Creek") Unit 7 be retired by October 31, 2015. Management subsequently decided to retire Widows Creek Unit 7 by September 30, 2015. As a result, depreciation expense is being further accelerated over the remaining useful life. This resulted in additional accelerated depreciation expense of $81 million during both the three and nine months ended June 30, 2015. It is expected that the decision to retire Widows Creek Unit 7 by September 30, 2015 will increase depreciation expense by approximately $137 million for the remainder of 2015. 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 June 30, 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	9 Months Ended
	Jun. 30, 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 became effective for TVA on October 1, 2014. Liabilities. In February 2013, the Financial Accounting Standards Board ("FASB") issued guidance on liabilities, which defines how entities measure obligations from joint and several liability arrangements for which the total amount of the obligation is fixed at the reporting date and for which no guidance exists, except for obligations addressed within existing guidance in GAAP. The guidance also requires entities to disclose the nature and amount of the obligation as well as other information about those obligations. The standard became effective for TVA on October 1, 2014, and is applied on a retrospective basis for all comparative periods presented. Adoption of this guidance did not have a material impact on TVA’s financial condition, results of operations, or cash flows. The following accounting standards have been issued, but as of June 30, 2015 , were not effective and have 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 July 2015, the FASB adopted 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, which affects a reporting entity’s evaluation of variable interests in entities in which it is involved in determining whether consolidation is required. 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. Debt Issuance Costs . In April 2015, the 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 the carrying amount of that debt liability, consistent with debt discounts. The recognition and measurement guidance for debt issuance costs are not affected by the amendments of this update. The standard becomes effective for TVA on October 1, 2016, and will be applied on a retrospective basis for all comparative periods presented. TVA has evaluated the impact of adopting this guidance, and if the guidance had been effective for TVA as of June 30, 2015 , TVA would have reclassified $ 75 million of debt issues costs from Other long-term assets as a reduction to Long-term power bonds, net and Long-term debt, net of variable interest entities. 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 and net realizable value. The guidance applies only to inventory valued using methods other than last-in, first out (“LIFO”) or the retail inventory method (for example first-in, first-out (“FIFO”) 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 that fiscal year, 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.

Restructuring

Restructuring	9 Months Ended
	Jun. 30, 2015
Restructuring and Related Activities [Abstract]
Restructuring	Restructuring TVA is undertaking cost reduction initiatives with the goal of keeping rates low, keeping reliability high, and continuing to fulfill its broader mission of environmental stewardship and economic development. TVA’s current focus is on reducing operating and maintenance costs through further efficiency gains and streamlining the organization. The goal is to reduce TVA’s operating and maintenance costs by $500 million by the end of 2015 as compared to its 2013 budget. As part of these cost reduction initiatives, an organizational restructuring occurred in 2014, which resulted in approximately 2,000 position reductions achieved through attrition, elimination of vacant positions, and employees leaving TVA either voluntarily or involuntarily. In May 2015, TVA announced a limited reduction in force for selected business units and anticipates another approximately 200 employees will be leaving TVA. Certain employees were eligible for severance payments as a result of these cost reduction initiatives. These severance amounts are included in Accounts payable and accrued liabilities and Other long-term liabilities, as applicable, on the Consolidated Balance Sheets. The restructuring expenses are included in Operating and maintenance on the Consolidated Statements of Operations. The table below summarizes the activity related to severance costs: Severance Cost Liability Activity Three Months Ended June 30 Nine Months Ended June 30 2015 2014 2015 2014 Severance cost liability at beginning of period $ 1 $ 32 $ 45 $ — Liabilities incurred during the period 7 21 7 56 Actual costs paid during the period (1 ) (7 ) (44 ) (10 ) Adjustments to estimate during the period — — (1 ) — Severance cost liability at end of period $ 7 $ 46 $ 7 $ 46 TVA plans to continue to evaluate its operations after it reaches its 2015 cost reduction goal. These evaluations could include additional staff restructuring and severance costs.

Accounts Receivable, Net

Accounts Receivable, Net	9 Months Ended
	Jun. 30, 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 June 30, 2015 At September 30, 2014 Power receivables $ 1,451 $ 1,576 Other receivables 125 101 Allowance for uncollectible accounts (1 ) (1 ) Accounts receivable, net $ 1,575 $ 1,676

Inventories, Net

Inventories, Net	9 Months Ended
	Jun. 30, 2015
Inventory, Net [Abstract]
Inventories, Net	Inventories, Net The table below summarizes the types and amounts of TVA’s inventories: Inventories, Net At June 30, 2015 At September 30, 2014 Fuel inventory $ 513 $ 473 Materials and supplies inventory 648 616 Emission allowance inventory, net 13 13 Allowance for inventory obsolescence (48 ) (46 ) Inventories, net $ 1,126 $ 1,056

Acquisition (Notes)

Acquisition (Notes)	9 Months Ended
	Jun. 30, 2015
Business Combinations [Abstract]
Acquisition	Acquisition On April 14, 2015, TVA acquired a 700 -megawatt combined-cycle gas plant located in Ackerman, Mississippi, from Quantum Choctaw Power, an affiliate of Quantum Utility Generation. TVA has purchased the electricity generated by the plant since 2008. TVA acquired the plant for total cash consideration of $342 million . The plant is located within TVA's service area and is already connected to TVA's transmission grid. The plant is expected to provide greater transmission flexibility and system reliability as TVA retires older, coal-burning units. The facility has been renamed Ackerman Combined Cycle Plant. The purchase price allocation of the fair value of the assets acquired consisted of $333 million of Completed plant, $6 million of Other long-term assets, and $3 million of Inventories, net. Transaction costs were expensed as incurred and were not material.

Other Long-Term Assets

Other Long-Term Assets	9 Months Ended
	Jun. 30, 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 June 30, 2015 At September 30, 2014 EnergyRight ® receivables $ 123 $ 123 Unamortized debt issue cost of power bonds and variable interest entities 75 68 Loans and other long-term receivables, net 108 87 Prepaid capacity payments 53 58 Restricted cash — 64 Currency swap asset, net 61 — Commodity contract derivative assets 1 — Other 110 83 Other long-term assets $ 531 $ 483 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 June 30, 2015 and September 30, 2014 , the carrying amount of the loans receivable, net of discount, reported in Accounts receivable, net was approximately $ 32 million and $ 33 million , respectively. See Note 11 for information regarding the associated financing obligation.

Regulatory Assets and Liabiliti

Regulatory Assets and Liabilities	9 Months Ended
	Jun. 30, 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 June 30, 2015 At September 30, 2014 Current regulatory assets Deferred nuclear generating units $ 236 $ 237 Unrealized losses on commodity derivatives 182 134 Environmental agreements 70 54 Environmental cleanup costs - Kingston ash spill 45 47 Fuel cost adjustment receivable 14 9 Other current regulatory assets 2 — Total current regulatory assets 549 481 Non-current regulatory assets Deferred pension costs and other post-retirement benefits costs 4,087 4,297 Deferred pension costs due to actions of regulator 171 — Unrealized losses on interest rate derivatives 1,028 957 Nuclear decommissioning costs 892 931 Environmental cleanup costs - Kingston ash spill 362 421 Non-nuclear decommissioning costs 720 645 Deferred nuclear generating units 1,097 1,255 Environmental agreements 63 108 Unrealized losses on commodity derivatives 81 72 Other non-current regulatory assets 286 308 Total non-current regulatory assets 8,787 8,994 Total regulatory assets $ 9,336 $ 9,475 Current regulatory liabilities Fuel cost adjustment tax equivalents $ 165 $ 182 Unrealized gains on commodity derivatives 3 2 Total current regulatory liabilities 168 184 Non-current regulatory liabilities Unrealized gains on commodity derivatives 1 — Total non-current regulatory liabilities 1 — Total regulatory liabilities $ 169 $ 184 Deferred Pension Costs Due to Actions of Regulator . In 2015, TVA began including its cash contributions to the pension plan in the rate-making formula; accordingly, on October 1, 2014, TVA began recognizing 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.

Variable Interest Entities

Variable Interest Entities	9 Months Ended
	Jun. 30, 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. The analysis to determine whether an entity is a VIE considers factors such as contracts with an entity, credit support for an entity, the adequacy of the equity investment of an entity, the extent of an entity's activities that either involve or are conducted on behalf of an investor with disproportionate voting rights, and the relationship of voting power to the amount of equity invested in an entity. A VIE is consolidated by its primary beneficiary. The primary beneficiary has both (i) the power to direct the activities that most significantly impact the entity's economic performance and (ii) the obligation to absorb losses or the right to receive benefits from the entity that could potentially be significant to the VIE. The determination of the primary beneficiary requires continual reassessment. 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. Southaven VIE On August 9, 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 scheduled amortizing, semi-annual payments due each August 15 and February 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. The sale of the SCCG notes, the membership interests in SCCG, and the SHLLC notes all closed on August 9, 2013. 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 scheduled pre-determined payments to be made to Seven States Southaven, LLC on each lease payment date by SHLLC as agreed in SHLLC’s formation documents (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. TVA participated in the design, business conduct, and financial support of SCCG and has determined that it has a direct variable interest in SCCG resulting from risk associated with the value of the Southaven CCF at the end of the lease term. Based on its analysis, TVA has determined that it is the primary beneficiary of SCCG and, as such, is required to account for the VIE on a consolidated basis. John Sevier VIE On January 17, 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 of Holdco are allocated. The membership interests held by Holdco in JSCCG were purchased with proceeds from the issuance of $ 100 million of secured notes (the “Holdco notes") and are subject to mandatory redemption pursuant to scheduled amortizing, semi-annual payments due each January 15 and July 15, with a final payment due on January 15, 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 all closed on January 17, 2012. The JSCCG notes are secured by TVA’s lease payments, and the Holdco notes are secured by Holdco's investment in, and amounts receivable from, JSCCG. TVA’s lease payments to JSCCG are equal to and payable on the same dates as JSCCG’s and Holdco’s semi-annual debt service payments. In addition to the lease payments, TVA pays administrative and miscellaneous expenses incurred by JSCCG and Holdco. Certain agreements related to this transaction contain default and acceleration provisions. Due to its participation in the design, business conduct, and credit and financial support of JSCCG and Holdco, TVA has determined that it has a variable interest in both of these entities. Based on its analysis, TVA has concluded that it is the primary beneficiary of JSCCG and Holdco and, as such, is required to account for the VIEs on a consolidated basis. Holdco’s membership interests in JSCCG are eliminated in consolidation. Impact on Consolidated Balance Sheets The financial statement items attributable to carrying amounts and classifications of JSCCG, Holdco, and SCCG as of June 30, 2015 and September 30, 2014 , as reflected in the consolidated balance sheets are as follows: Summary of Impact of VIEs on Consolidated Balance Sheets At June 30, 2015 At September 30, 2014 Current liabilities of VIE Accrued interest of VIE $ 26 $ 12 Current portion of membership interests of VIE subject to mandatory redemption 2 2 Current maturities of long-term debt of VIE 33 32 Total current liabilities of VIE 61 46 Other liabilities of VIE Membership interests of VIE subject to mandatory redemption 36 37 Long-term debt of VIE, net Long-term debt of VIE 1,263 1,279 Total liabilities of VIE $ 1,360 $ 1,362 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.

Kingston Fossil Plant Ash Spill

Kingston Fossil Plant Ash Spill	9 Months Ended
	Jun. 30, 2015
Environmental Remediation Obligations [Abstract]
Kingston Fossil Plant Ash Spill	Kingston Fossil Plant Ash Spill The Event In December 2008, one of the dredge cells at the Kingston Fossil Plant ("Kingston") failed, and over five million cubic yards of water and coal fly ash flowed out of the cell. TVA, in coordination with federal and state agencies, has completed cleanup and recovery efforts. TVA completed the removal of time-critical ash from the river during the third quarter of 2010. In November 2012, the Environmental Protection Agency ("EPA") and the Tennessee Department of Environment and Conservation ("TDEC") approved a plan to allow the Emory River's natural processes to remediate the remaining ash in the river, and to conduct a long-term monitoring program. TVA submitted a final completion report to the EPA on April 22, 2015, for review and approval. Claims and Litigation See Note 19 — Legal Proceedings — Legal Proceedings Related to the Kingston Ash Spill and Civil Penalty and Natural Resource Damages for the Kingston Ash Spill . Financial Impact TVA recorded an estimate of $ 1.1 billion for the cost of cleanup related to this event. In August 2009, TVA began using regulatory accounting treatment to defer all actual costs already incurred and expected future costs related to the ash spill. The cost is being charged to expense as it is collected in rates over 15 years , beginning October 1, 2009. Amounts spent since the event through June 30, 2015 , totaled $ 1.1 billion . The remaining estimated liability at June 30, 2015 , was $ 18 million and is included in Accounts payable and accrued liabilities and Other long-term liabilities. TVA has not included the following categories of costs in the above estimate since it has been determined that these costs are currently either not probable or not reasonably estimable: penalties (other than the penalties set out in a June 2010 TDEC order), regulatory directives, natural resources damages (other than payments required under a memorandum of agreement with TDEC and the U.S. Fish and Wildlife Service establishing a process and a method for resolving the natural resource damages claim), future lawsuits, future claims, long-term environmental impact costs, final long-term disposition of the ash processing area, and costs associated with new laws and regulations. There are certain other costs that will be incurred that have not been included in the estimate as they are appropriately accounted for in other areas of the consolidated financial statements. Associated capital asset purchases are recorded in property, plant, and equipment except for $ 12 million classified as assets held for sale and recorded in Other current assets. Ash handling and disposition costs from current plant operations are recorded in operating expenses. A portion of the dredge cell closure costs are also excluded from the estimate, as they are included in the non-nuclear ARO liability. Insurance TVA had property and excess liability insurance programs in place at the time of the Kingston ash spill. TVA pursued claims under both the property and excess liability programs and has settled all of its property insurance claims and some of its excess liability insurance claims. In April 2012, TVA initiated arbitration proceedings against the remaining excess liability insurance companies in accordance with the policies’ dispute resolution provisions. TVA is seeking recovery of certain costs incurred in the cleanup project, including the costs of removing ash from property or waters owned by the State of Tennessee, and related expenses. TVA has received insurance proceeds of $ 317 million .

Other Long-Term Liabilities

Other Long-Term Liabilities	9 Months Ended
	Jun. 30, 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 19 — Legal Proceedings — Environmental Agreements ). The table below summarizes the types and amounts of Other long-term liabilities: Other Long-Term Liabilities At June 30, 2015 At September 30, 2014 Interest rate swap liabilities $ 1,419 $ 1,348 Environmental Agreements liability 63 108 EnergyRight ® financing obligation 149 152 Membership interests of VIE subject to mandatory redemption 36 37 Commodity contract derivative liabilities 29 17 Currency swap liabilities 23 15 Commodity swap derivative liabilities 11 14 Other 289 271 Total other long-term liabilities $ 2,019 $ 1,962 EnergyRight ® Financing Obligation . TVA purchases certain loans receivable from its LPCs in association with the EnergyRight ® Solutions program. Depending on the nature of the energy-efficiency project, loans may have a maximum term of five years or ten years . 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 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 June 30, 2015 and September 30, 2014 , the carrying amount of the financing obligation reported in Accounts payable and accrued liabilities was approximately $37 million and $ 38 million , respectively. See Note 7 for information regarding the associated loans receivable. Membership Interests of VIE Subject to Mandatory Redemption. On August 9, 2013, SCCG issued 100 percent of its membership interests to SHLLC for a total of $ 40 million . The membership interests in SCCG are mandatorily redeemable pursuant to a schedule of payments that indicates the amount of each payment and the corresponding dates on which each payment is due. The schedule requires SCCG to make semi-annual payments to SHLLC sufficient to provide returns on, as well as returns of, capital until the investment has been repaid in full, including a $ 4 million balloon payment as part of the final disbursement which is due on August 15, 2033. The return on capital includes the Seven States Return. These payments provide a return on investment to SHLLC of 7.0 percent , which is reflected as interest expense in the consolidated statements of operations. As of June 30, 2015 and September 30, 2014 , the carrying amount of the membership interests of VIE subject to mandatory redemption were $ 38 million and $ 39 million , respectively. As of June 30, 2015 and September 30, 2014 , $ 2 million of this was current and included in Accounts payable and accrued liabilities. 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. See Note 9 — Southaven VIE .

Asset Retirement Obligations

Asset Retirement Obligations	9 Months Ended
	Jun. 30, 2015
Asset Retirement Obligation Disclosure [Abstract]
Asset Retirement Obligations	Asset Retirement Obligations During the nine months ended June 30, 2015 , TVA's total ARO liability increased $ 687 million . In April 2015, the EPA published its final rule governing coal combustion residuals, which will regulate landfill and impoundment location, design, and operations; dictate certain pond-closure conditions; and establish groundwater monitoring and closure and post-closure standards. As a result of the ruling, TVA has made revisions to the assumptions and estimates used to calculate asset retirement obligations. Increases to estimated project costs, including expansion of work scope and higher costs of materials, have resulted in TVA recording a $539 million increase to the ARO liability during the three months ended June 30, 2015. TVA is continuing to evaluate the rules and their impact on its operations, including the cost and timing estimates of related projects. As a result, adjustments to its ARO liabilities may be required as estimates are refined. TVA also recorded an additional $60 million of other new AROs related to TVA’s coal-fired plants and a $7 million ARO related to the Ackerman Combined Cycle Plant acquisition during the same period. See Note 6 . 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. Decommissioning cost studies will be updated for each of TVA’s nuclear units at least every five years . Both the nuclear and non-nuclear liabilities were increased by periodic accretion. This was partially offset by ash area settlement projects that were conducted during the nine months ended June 30, 2015 . The nuclear and non-nuclear accretion were deferred as regulatory assets, and $ 33 million of the related regulatory assets was amortized into expense as this amount was collected in rates. Asset Retirement Obligation Activity Nuclear Non-Nuclear Total Balance at September 30, 2014 $ 2,052 $ 1,117 $ 3,169 Settlements (ash storage areas) — (33 ) (33 ) Additional obligations — 606 606 Accretion (recorded as regulatory asset) 74 40 114 Balance at June 30, 2015 $ 2,126 $ 1,730 $ 3,856 (1 ) Note (1) The current portion of ARO in the amount of $ 180 million is included in Accounts payable and accrued liabilities at June 30, 2015 .

Debt and Other Obligations

Debt and Other Obligations	9 Months Ended
	Jun. 30, 2015
Debt Disclosure [Abstract]
Debt and Other Obligations	Debt and Other Obligations Debt Outstanding Total debt outstanding at June 30, 2015 , and September 30, 2014 , consisted of the following: Debt Outstanding At June 30, 2015 At September 30, 2014 Short-term debt Short-term debt, net $ 2,582 $ 596 Current maturities of long-term debt of variable interest entities 33 32 Current maturities of power bonds 32 1,032 Total current debt outstanding, net 2,647 1,660 Long-term debt Long-term debt of variable interest entities 1,263 1,279 Long-term power bonds (1) 21,827 22,037 Unamortized discounts, premiums, and other (83 ) (89 ) Total long-term debt, net 23,007 23,227 Total outstanding debt $ 25,654 $ 24,887 Note (1) Includes net exchange losses from currency transactions of $ 14 million at June 30, 2015 and $ 44 million at September 30, 2014 . Debt Securities Activity The table below summarizes the long-term debt securities activity for the period from October 1, 2014, to June 30, 2015 : Debt Securities Activity Date Amount Interest Rate Redemptions/Maturities electronotes ® First Quarter 2015 $ 1 2.65 % electronotes ® Second Quarter 2015 42 4.20 % electronotes ® Third Quarter 2015 19 4.05 % 2009 Series A November 2014 2 2.25 % 2009 Series B December 2014 1 3.77 % 1999 Series A May 2015 38 3.96 % 2009 Series A May 2015 1 2.25 % 1998 Series D June 2015 50 3.83 % 2009 Series B June 2015 26 3.77 % 2005 Series B June 2015 1,000 4.38 % Total redemptions/maturities of power bonds 1,180 Variable interest entities Second Quarter 2015 15 4.29 % Total redemptions/maturities of debt $ 1,195 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 2015 with a maturity date of September 30, 2015. 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 June 30, 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 . One $ 1.0 billion credit facility matures on December 13, 2017, another $ 500 million credit facility matures on April 5, 2018, and one $1.0 billion credit facility matures on June 2, 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 June 30, 2015 , and September 30, 2014 , there were approximately $ 1.1 billion and $ 1.0 billion , respectively, of letters of credit outstanding under the facilities, and there were no borrowings outstanding. See Note 15 — Other Derivative Instruments — Collateral . The following table provides additional information regarding TVA's funding available in the form or three long-term credit facilities: Summary of Long-Term Credit Facilities At June 30, 2015 (in billions) Maturity Date Facility Limit Letters of Credit Outstanding Cash Borrowings Availability December 2017 $ 1.0 $ 0.3 $ — $ 0.7 April 2018 0.5 0.5 — — June 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 June 30, 2015 , and September 30, 2014 , the outstanding lease/leaseback obligations were $ 617 million and $ 691 million , respectively.

Accumulated Other Comprehensive

Accumulated Other Comprehensive Income (Loss)	9 Months Ended
	Jun. 30, 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 and nine months ended June 30, 2015 , TVA reclassified $ 53 million and $ (31) million of gains (losses), respectively, related to its cash flow hedges from AOCI to Interest expense. During the three and nine months ended June 30, 2014 , TVA reclassified $ 26 million and $ 55 million of gains, respectively, related to its cash flow hedges from AOCI to Interest expense. See Note 15 . 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 8 , Note 15 — Overview of Accounting Treatment , Note 16 — Fair Value Measurements, and Note 18 .

Risk Management Activities and

Risk Management Activities and Derivative Transactions	9 Months Ended
	Jun. 30, 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 June 30 Nine Months Ended June 30 Derivatives in Cash Flow Hedging Relationship Objective of Hedge Transaction Accounting for Derivative Hedging Instrument 2015 2014 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 $ 62 $ 1 $ (12 ) $ 23 Summary of Derivative Instruments That Receive Hedge Accounting Treatment (part 2) Amount of Gain (Loss) Reclassified from OCI to Interest Expense Three Months Ended Nine Months Ended Derivatives in Cash Flow Hedging Relationship 2015 2014 2015 2014 Currency swaps $ 53 $ 26 $ (31 ) $ 55 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 $ 91 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 June 30 ( 1) Nine Months Ended June 30 (1) Derivative Type Objective of Derivative Accounting for Derivative Instrument 2015 2014 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 until settlement, at which time the gains/losses are recognized in gain/loss on derivative contracts. $ — $ — $ — $ — 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. (30 ) (6 ) (69 ) (29 ) 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 and nine months ended June 30, 2015 and 2014 . Fair Values of TVA Derivatives At June 30, 2015 At September 30, 2014 Derivatives that Receive Hedge Accounting Treatment Balance Balance Sheet Presentation Balance Balance Sheet Presentation Currency swaps £200 million Sterling $ (23 ) Other long-term liabilities $ (15 ) Other long-term liabilities £250 million Sterling 49 Other long-term assets 56 Other long-term assets £150 million Sterling 12 Other long-term assets 8 Other long-term assets At June 30, 2015 At September 30, 2014 Derivatives that Do Not Receive Hedge Accounting Treatment Balance Balance Sheet Presentation Balance Balance Sheet Presentation Interest rate swaps $1.0 billion notional (1,034 ) Other long-term liabilities (987 ) Other long-term liabilities $476 million notional (373 ) Other long-term liabilities (349 ) Other long-term liabilities $42 million notional (12 ) Other long-term liabilities (12 ) Other long-term liabilities Commodity contract derivatives (125 ) Other current assets $2; Other long-term assets $1; Other long-term liabilities $(29); Accounts payable and accrued liabilities $(99) (96 ) Other current assets $1; Other long-term liabilities $(17); Accounts payable and accrued liabilities $(80) FTP Derivatives under FTP (1) (125 ) Other current assets $(91); Other long-term liabilities $(11); Accounts payable and accrued liabilities $(23) (103 ) Other current assets $(69); Other long-term liabilities $(14); Accounts payable and accrued liabilities $(20) Note (1) Fair values of certain derivatives under the FTP that were in net liability positions totaling $ 91 million and $ 69 million at June 30, 2015 and September 30, 2014 , 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 June 30, 2015 : Currency Swaps Outstanding At June 30, 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 June 30, 2015 and 2014 , the changes in fair market value of the interest rate swaps resulted in deferred unrealized gains (losses) of $ 278 million and $ (65) million , respectively. For the nine months ended June 30, 2015 and 2014 , the changes in fair market value of the interest rate swaps resulted in deferred unrealized gains (losses) of $ (71) million and $ (90) 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 June 30, 2015 , TVA's coal and natural gas contract derivatives both had terms of up to three years . Commodity Contract Derivatives At June 30, 2015 At September 30, 2014 Number of Contracts Notional Amount Fair Value (MtM) Number of Contracts Notional Amount Fair Value ( MtM ) Coal contract derivatives 13 22 million tons $ (128 ) 24 31 million tons $ (86 ) Natural gas contract derivatives 36 146 million mmBtu $ 3 46 62 million mmBtu $ (10 ) Derivatives Under FTP. While TVA is currently evaluating the use of financial instruments for price hedging, certain natural gas swaps remain as part of the suspended FTP. Under the FTP, TVA may 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. At June 30, 2015 and September 30, 2014 , the risks hedged under the FTP were the economic risks associated with the prices of natural gas, fuel oil, and crude oil. At June 30, 2015 and September 30, 2014 , TVA had no outstanding coal contract derivatives under the FTP. At June 30, 2015 , there were no futures contracts or options contracts outstanding under the FTP, and swap contracts under the FTP had remaining terms of three years or less. Derivatives Under Financial Trading Program At June 30, 2015 At September 30, 2014 Notional Amount Fair Value (MtM) (in millions) Notional Amount Fair Value (MtM) (in millions) Natural gas (in mmBtu) Swap contracts 63,835,000 $ (125 ) 102,227,500 $ (103 ) 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 $ (10) million at June 30, 2015 , and $ (5) million at September 30, 2014 . 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 June 30, 2015 At September 30, 2014 FTP unrealized gains (losses) deferred as regulatory liabilities (assets) Natural gas $ (125 ) $ (103 ) Financial Trading Program Realized Gains (Losses) For the Three Months Ended June 30 For the Nine Months Ended June 30 2015 2014 2015 2014 Decrease (increase) in fuel expense Natural gas $ (24 ) $ (5 ) $ (56 ) $ (23 ) Fuel oil/crude oil — — 1 2 Financial Trading Program Realized Gains (Losses) For the Three Months Ended For the Nine Months Ended 2015 2014 2015 2014 Decrease (increase) in purchased power expense Natural gas $ (6 ) $ (1 ) $ (14 ) $ (9 ) Offsetting of Derivative Assets and Liabilities The amounts of TVA's derivative instruments as reported in the Consolidated Balance Sheets as of June 30, 2015 , and September 30, 2014 , are shown in the table below: As of June 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) $ 61 $ — $ 61 Commodity derivatives under FTP 55 (55 ) — Total derivatives subject to master netting or similar arrangement 116 (55 ) 61 Total derivatives not subject to master netting or similar arrangement 3 — 3 Total $ 119 $ (55 ) $ 64 Liabilities Currency swap(s) (4) $ 23 $ — $ 23 Interest rate swaps (4) 1,419 — 1,419 Commodity derivatives under FTP 180 (146 ) 34 Total derivatives subject to master netting or similar arrangement 1,622 (146 ) 1,476 Total derivatives not subject to master netting or similar arrangement 128 — 128 Total $ 1,750 $ (146 ) $ 1,604 As of September 30, 2014 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) $ 64 $ (64 ) $ — Commodity derivatives under FTP 51 (51 ) — Total derivatives subject to master netting or similar arrangement 115 (115 ) — Total derivatives not subject to master netting or similar arrangement 1 — 1 Total $ 116 $ (115 ) $ 1 Liabilities Currency swap(s) (4) $ 15 $ — $ 15 Interest rate swaps (4) 1,348 — 1,348 Commodity derivatives under FTP 154 (120 ) 34 Total derivatives subject to master netting or similar arrangement 1,517 (120 ) 1,397 Total derivatives not subject to master netting or similar arrangement 97 — 97 Total $ 1,614 $ (120 ) $ 1,494 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 Consolidated Balance Sheets. (3) At June 30, 2015 , securities of approximately $ 9 million were 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 and $1.0 billion were posted as collateral at June 30, 2015 and September 30, 2014 , respectively, 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. At June 30, 2015 , TVA held no cash collateral in excess of collateral requirements and at September 30, 2014 , TVA held $19 million of cash collateral in excess of collateral requirements that was classified in Restricted cash and investments with a corresponding obligation recorded in Accounts payable and accrued liabilities in the same amount. Other Derivative Instruments Investment Fund Derivatives . Investment funds consist primarily of funds held in the Nuclear Decommissioning Trust ("NDT") , the Asset Retirement Trust ("ART") , and a Rabbi Trust. The funds in the Rabbi Trust are held for the Supplemental Executive Retirement Plan ("SERP") , the Long-Term Deferred Compensation Plan ("LTDCP") , and the TVA Deferred Compensation Plan ("DCP") . All securities in the trusts are classified as trading. See Note 16 — Investments 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 June 30, 2015 , and September 30, 2014 , the fair value of 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 June 30, 2015 , the aggregate fair value of all derivative instruments with credit-risk related contingent features that were in a liability position was $ 1.4 billion . TVA's collateral obligations at June 30, 2015 , under these arrangements were approximately $ 1.0 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 accounts receivable from three LPCs that represented 26 percent and 27 percent of total outstanding accounts receivable at June 30, 2015 and September 30, 2014 , respectively. Credit of Derivative Counterparties . TVA has entered into derivative contracts for hedging purposes, and TVA's NDT fund and 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 June 30, 2015 , all of TVA's currency swaps, interest rate swaps, and commodity derivatives under the FTP were with counterparties whose Moody's credit rating was Baa1 or higher. At June 30, 2015 , all of TVA's coal contract derivatives were with counterparties whose Moody's credit rating, or TVA's internal analysis when such information was unavailable, was Ca or higher, except for one counterparty whose rating was D. See Derivatives Not Receiving Hedge Accounting Treatment . 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 June 30, 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). 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	9 Months Ended
	Jun. 30, 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. Investments At June 30, 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, the ART, and a Rabbi Trust. The funds in the Rabbi Trust are held for the SERP, LTDCP, and DCP. The NDT holds funds for the ultimate decommissioning of TVA's nuclear power plants. The ART holds funds primarily for the costs related to the future closure and retirement of TVA's other long-lived assets. 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. TVA established the DCP to provide participants with deferrals of compensation as a supplement to retirement benefits. The NDT and SERP are invested in a mix of investments generally designed to achieve a return in line with overall equity market performance, and the ART and LTDCP are invested in a mix of investments generally designed to achieve a return in line with equity and fixed-income market performance. The NDT, ART, SERP, LTDCP, and DCP 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 $ 92 million at June 30, 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 Level 3 within the fair value hierarchy. Commingled funds represent investment funds comprising multiple individual financial instruments. The commingled funds held by the NDT, ART, SERP, LTDCP, and DCP consist of 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 (Level 1) or measured using observable inputs for similar instruments (Level 2). 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 Level 2 valuations. 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 June 30 For the Nine Months Ended June 30 Financial Statement Presentation 2015 2014 2015 2014 SERP Other income (expense) $ — $ 1 $ — $ 2 LTDCP Other income (expense) — — (1 ) — NDT Regulatory asset (19 ) 36 15 72 ART Regulatory asset (3 ) 9 12 27 Currency and Interest Rate Swaps See Note 15 — 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. Coal and natural gas commodity contracts are classified as Level 3 and Level 2 valuations, respectively, and are valued based on income approaches. TVA develops an overall price forecast using widely used short-term and mid-range market data from an external pricing specialist. In addition, coal commodity contracts include adjustments for long-term internal estimates. To value the volume option component of applicable coal contracts, TVA uses a Black-Scholes pricing model which includes inputs from the overall coal price forecast, contract-specific terms, and other market inputs. 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 15 — Derivatives Not Receiving Hedge Accounting Treatment — Commodity Derivatives and — Derivatives Under FTP for a discussion of the nature and purpose of coal and natural gas 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 2014) 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 $ 4 million decrease in the fair value of assets and a $ 1 million decrease in the fair value of liabilities at June 30, 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 June 30, 2015 , and September 30, 2014 . 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 June 30, 2015 Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total Assets Investments Equity securities $ 181 $ — $ — $ 181 Debt securities U.S. government corporations and agencies 59 7 — 66 Corporate debt securities — 336 — 336 Residential mortgage-backed securities — 16 — 16 Commercial mortgage-backed securities — 5 — 5 Collateralized debt obligations — 29 — 29 Private partnerships — — 238 238 Commingled funds (1) Equity security commingled funds 44 942 — 986 Debt security commingled funds 44 178 — 222 Total investments 328 1,513 238 2,079 Currency swap(s) (2) — 61 — 61 Commodity contract derivatives — — 3 3 Commodity derivatives under FTP (2) Swap contracts — — — — Total $ 328 $ 1,574 $ 241 $ 2,143 Quoted Prices in Active Markets for Identical Liabilities (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total Liabilities Currency swap(s) (2) $ — $ 23 $ — $ 23 Interest rate swaps — 1,419 — 1,419 Commodity contract derivatives — — 128 128 Commodity derivatives under FTP (2) Swap contracts — 34 — 34 Total $ — $ 1,476 $ 128 $ 1,604 Notes (1) Commingled funds represent investment funds comprising multiple individual financial instruments and are classified in the table based on their existing investment portfolio as of the measurement date. Commingled funds primarily composed of one class of security are classified in that category. (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 any cash collateral received from or paid to the counterparty, to the extent such amount is not recorded in Accounts payable and accrued liabilities. See Note 15 — Offsetting of Derivative Assets and Liabilities . Fair Value Measurements At September 30, 2014 Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total Assets Investments Equity securities $ 162 $ — $ — $ 162 Debt securities U.S. government corporations and agencies 46 39 — 85 Corporate debt securities — 290 — 290 Residential mortgage-backed securities — 14 — 14 Commercial mortgage-backed securities — 7 — 7 Collateralized debt obligations — 29 — 29 Private partnerships — — 214 214 Commingled funds (1) Equity security commingled funds 40 903 — 943 Debt security commingled funds 61 176 — 237 Total investments 309 1,458 214 1,981 Currency swap(s) (2) — — — — Commodity contract derivatives — — 1 1 Commodity derivatives under FTP (2) Swap contracts — — — — Total $ 309 $ 1,458 $ 215 $ 1,982 Quoted Prices in Active Markets for Identical Liabilities (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total Liabilities Currency swap(s) (2) $ — $ 15 $ — $ 15 Interest rate swaps — 1,348 — 1,348 Commodity contract derivatives — — 97 97 Commodity derivatives under FTP (2) Swap contracts — 34 — 34 Total $ — $ 1,397 $ 97 $ 1,494 Notes (1) Commingled funds represent investment funds comprising multiple individual financial instruments and are classified in the table based on their existing investment portfolio as of the measurement date. Commingled funds primarily composed of one class of security are classified in that category. (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 any cash collateral received from or paid to the counterparty. See Note 15 — Offsetting of Derivative Assets and Liabilities . TVA uses internal and external valuation specialists for the calculation of its 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 assets and liabilities measured at fair value on a recurring basis using significant unobservable inputs (Level 3): Fair Value Measurements Using Significant Unobservable Inputs For the Three Months Ended For the Nine Months Ended Private Partnerships Commodity Contract Derivatives Private Partnerships Commodity Contract Derivatives Balance at beginning of period $ 180 $ (131 ) $ 159 $ (140 ) Purchases 7 — 23 — Issuances — — — — Sales (6 ) — (7 ) — Settlements — — — — Net unrealized gains (losses) deferred as regulatory assets and liabilities 7 (15 ) 13 (6 ) Balance at June 30, 2014 $ 188 $ (146 ) $ 188 $ (146 ) Balance at beginning of period $ 223 $ (149 ) $ 214 $ (96 ) Purchases 11 — 21 — Issuances — — — — Sales (5 ) — (12 ) — Settlements — — — — Net unrealized gains (losses) deferred as regulatory assets and liabilities 9 24 15 (29 ) Balance at June 30, 2015 $ 238 $ (125 ) $ 238 $ (125 ) There were no realized gains or losses related to the instruments measured at fair value using significant unobservable inputs that affected net income during the three and nine months ended June 30, 2015 . All unrealized gains and losses related to these instruments have been reflected as increases or decreases in regulatory assets and liabilities. See Note 8 . 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 June 30 2015 Valuation Technique(s) Unobservable Inputs Range Assets Commodity contract derivatives $ 3 Pricing model Coal supply and demand 0.8 - 1.0 billion tons/year Long-term market prices $10.08 - $103.41/ton Liabilities Commodity contract derivatives $ 128 Pricing model Coal supply and demand 0.8 - 1.0 billion tons/year Long-term market prices $10.08 - $103.41/ton Quantitative Information about Level 3 Fair Value Measurements Fair Value at September 30 2014 Valuation Technique(s) Unobservable Inputs Range Assets Commodity contract derivatives $ 1 Discounted cash flow Credit risk 2 - 5 % (1) Pricing model Coal supply and demand 1.0 - 1.1 billion tons/year Long-term market prices $11.24 - $67.07/ton Liabilities Commodity contract derivatives $ 97 Pricing model Coal supply and demand 1.0 - 1.1 billion tons/year Long-term market prices $11.24 - $67.07/ton Note (1) Applies to two contracts. 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 June 30, 2015 , and September 30, 2014 , 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 June 30, 2015 , and September 30, 2014 , were as follows: Estimated Values of Financial Instruments Not Recorded at Fair Value At June 30, 2015 At September 30, 2014 Valuation Classification Carrying Amount Fair Value Carrying Amount Fair Value EnergyRight ® receivables (including current portion) Level 2 $ 155 $ 163 $ 156 $ 166 Loans and other long-term receivables, net (including current portion) Level 2 $ 111 $ 99 $ 92 $ 81 EnergyRight ® financing obligation (including current portion) Level 2 $ 186 $ 209 $ 190 $ 215 Unfunded loan commitments Level 2 $ — $ 20 $ — $ 18 Membership interest of variable interest entity subject to mandatory redemption (including current portion) Level 2 $ 38 $ 47 $ 39 $ 50 Long-term outstanding power bonds (including current maturities), net Level 2 $ 21,776 $ 25,134 $ 22,980 $ 26,889 Long-term debt of variable interest entities (including current maturities) Level 2 $ 1,296 $ 1,392 $ 1,311 $ 1,425 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 values of the EnergyRight ® Solutions receivables, loans and other long-term receivables, and unfunded loan commitments are estimated by determining the present values of future cash flows using discount rates equal to lending rates for similar loans made to borrowers with similar credit ratings and similar remaining maturities, where applicable. The fair value of the 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 values of the EnergyRight ® Solutions financing obligation and membership interests and long-term debt of VIEs are estimated by determining the present value of future cash flows using current market rates for similar obligations, giving effect to credit ratings and remaining maturities.

Other Income (Expense), Net

Other Income (Expense), Net	9 Months Ended
	Jun. 30, 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 For the Nine Months Ended 2015 2014 2015 2014 Interest income $ 6 $ 6 $ 18 $ 17 External services 3 3 9 15 Gains (losses) on investments — 2 3 4 Miscellaneous (1 ) (1 ) (5 ) 1 Total other income (expense), net $ 8 $ 10 $ 25 $ 37

Benefit Plans

Benefit Plans	9 Months Ended
	Jun. 30, 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 and nine months ended June 30, 2015 , and 2014 , were as follows: Components of TVA’s Benefit Plans For the Three Months Ended June 30 For the Nine Months Ended June 30 Pension Benefits Other Post-Retirement Benefits Pension Benefits Other Post-Retirement Benefits 2015 2014 2015 2014 2015 2014 2015 2014 Service cost $ 32 $ 33 $ 4 $ 5 $ 97 $ 98 $ 12 $ 14 Interest cost 135 139 7 8 405 418 22 24 Expected return on plan assets (110 ) (109 ) — — (328 ) (326 ) — — Amortization of prior service credit (5 ) (5 ) (2 ) (2 ) (16 ) (16 ) (5 ) (5 ) Recognized net actuarial loss 75 71 3 3 225 214 7 8 Total net periodic benefit cost as actuarially determined 127 129 12 14 383 388 36 41 Amount capitalized due to actions of regulator (57 ) — — — (171 ) — — — Total net periodic benefit cost $ 70 $ 129 $ 12 $ 14 $ 212 $ 388 $ 36 $ 41 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 expects to contribute $ 275 million to the Plan in 2015. As of June 30, 2015 , TVA had contributed $ 138 million to the Plan and expects to contribute the remaining $ 137 million by September 30, 2015. TVA contributed $ 250 million to the Plan in 2014. TVA does not separately set aside assets to fund other benefit costs, but rather funds such costs on an as-paid basis. For the nine months ended June 30, 2015 , TVA provided approximately $ 31 million , net of rebates and subsidies, to other post-retirement benefit plans and approximately $ 7 million to the SERP. For the nine months ended June 30, 2014 , TVA provided approximately $ 23 million , net of rebates and subsidies, to other post-retirement benefit plans and approximately $ 6 million to the SERP.

Contingencies and Legal Proceed

Contingencies and Legal Proceedings	9 Months Ended
	Jun. 30, 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 102 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 six licensed units, TVA could be required to pay a maximum of $ 764 million per nuclear incident, but it would have to pay no more than $ 114 million per incident in any one year. When the contributions of the nuclear plant licensees are added to the insurance proceeds of $ 375 million , $ 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. Nuclear . 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 June 30, 2015 , the present value of the estimated future decommissioning cost of $ 2.1 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. 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 nuclear power units are currently authorized to operate until 2020-2036, depending on the unit. It may be possible to extend the operating life of some of the units with approval from the NRC. See Note 8 and Note 12 . Non-Nuclear Decommissioning . The present value of the estimated future non-nuclear decommissioning ARO was $ 1.7 billion at June 30, 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 non-nuclear power assets. 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. See Note 8 and Note 12 . 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 $800 million from 2015 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 oil spills and other contamination that TVA is addressing. At June 30, 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 $ 9 million on a non-discounted basis, and was included in Accounts payable and accrued liabilities and Other long-term liabilities on the consolidated balance sheet. 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 June 30, 2015 , TVA had accrued $ 145 million of probable losses with respect to Legal Proceedings. Of the accrued amount, $ 63 million is included in Other long-term liabilities and $ 82 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. Legal Proceedings Related to the Kingston Ash Spill . Seventy-eight lawsuits based on the Kingston ash spill were filed in the United States District Court for the Eastern District of Tennessee. Fifteen of these lawsuits were dismissed. On August 4, 2014, the court issued an agreed order that implements a mediated global resolution of pending claims. Under the order, the 63 pending cases were dismissed with prejudice, and TVA deposited $ 28 million with the court, which is responsible for disbursing the funds. The order anticipates that further legal proceedings will be required to resolve the claims of nine of the plaintiffs, and a portion of the $ 28 million was set aside under the order to cover the anticipated costs of resolving these claims. Claims of seven of the nine plaintiffs have been resolved. In April 2015, the court dismissed the claims of the remaining two plaintiffs, and these plaintiffs did not appeal the dismissal of their claims. Civil Penalty and Natural Resource Damages for the Kingston Ash Spill . In June 2010, TDEC issued a civil penalty order of approximately $ 12 million to TVA for the Kingston ash spill, citing violations of the Tennessee Solid Waste Disposal Act and the Tennessee Water Quality Control Act. Of the $ 12 million , TVA initially paid $ 10 million , and agreed to undertake environmental projects valued at $ 2 million as a credit against the remaining penalty amount. TVA completed several of those projects and paid TDEC the small remaining difference rather than do more projects. In addition, TVA paid $ 750 thousand over three years into the Natural Resource Restoration Fund associated with the Kingston spill. In July 2015, TDEC, TVA and the United States Department of the Interior entered into an administrative order on consent which determined that TVA’s restoration activities were the appropriate measures to remedy any natural resource damages, and released TVA from any claims for such damages. 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 against the six then-current members of the TVARS Board. The lawsuit challenged the TVARS Board's decision to suspend the TVA contribution requirements for 2010 through 2013, and to amend the TVARS Rules and Regulations to (1) reduce the calculation for COLA benefits for CY 2010 through CY 2013, (2) reduce the interest crediting rate for the fixed fund accounts, and (3) increase the eligibility age to receive COLAs from age 55 to 60 . In September 2010, the district court dismissed this action, allowing the plaintiffs to file an amended complaint within 14 days against TVARS and TVA but not the individual directors, which the plaintiffs did shortly thereafter. The plaintiffs allege, among other things, violations of their constitutional rights (due process, equal protection, and property rights), violations of the Administrative Procedure Act, and breach of statutory duties owed to the plaintiffs. They seek a declaratory judgment and appropriate relief for the alleged statutory and constitutional violations and breaches of duty. TVA filed its answer to the amended complaint in December 2010. In May 2012, the court granted the parties' joint motion to administratively close the case subject to reopening to allow the parties the opportunity to engage in mediation. In July 2013, the court granted the plaintiffs' motion to reopen the lawsuit. In November 2013, TVA filed a motion for summary judgment, and the plaintiffs filed a motion for summary judgment on February 8, 2015. The motions are pending before the court. 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. 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 the NRC licensing activities since 1984. The most recent update provided that a permanent repository would be available when necessary and that spent fuel could be safely stored for 60 years after a plant's operating license was terminated. The D.C. Circuit vacated this update on the grounds that, among other things, the NRC failed to support these findings with an adequate National Environmental Policy Act ("NEPA") review and the NRC did not evaluate environmental impacts if the repository was never built. In June 2012, multiple intervenor groups submitted a petition to the NRC to (1) hold in abeyance all pending reactor licensing decisions that would depend upon the WCD and (2) establish a process for ensuring that the remanded proceeding complies with the public participation requirements of Section 189a of the Atomic Energy Act. In August 2012, the NRC issued an order (the "August 2012 NRC Order") preventing the issuance of a final licensing decision in all proceedings affected by the petition, including the proceedings involving Watts Bar Nuclear Plant ("Watts Bar") Unit 2, Sequoyah Nuclear Plant ("Sequoyah") , and Bellefonte Nuclear Plant ("Bellefonte") Units 3 and 4. In August 2014, the NRC issued its final rule on continued storage of spent nuclear fuel ("Continued Storage Rule") , which replaced the WCD, and terminated its suspension of final licensing decisions, dismissed contentions related to the WCD pending before the NRC, and directed Atomic Safety and Licensing Boards ("ASLBs") to dismiss contentions related to the WCD that were being held in abeyance. In September 2014, multiple intervenor groups submitted a petition to the NRC in multiple reactor licensing proceedings to suspend the issuance of final decisions in those proceedings until the NRC generically makes additional findings related to spent fuel disposal or those findings are made in individual licensing proceedings. The NRC rejected this petition in February 2015. In addition, several petitions for review were filed in October 2014 in the D.C. Circuit challenging the Continued Storage Rule. In January 2015, multiple intervenor groups submitted a petition to the NRC in multiple reactor licensing proceedings, asking the NRC to direct its staff to supplement environmental impact statements to incorporate by reference the generic environmental impact statement released in connection with the Continued Storage Rule. The NRC rejected this petition. 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 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. Administrative Proceedings Regarding Bellefonte Units 3 and 4 . TVA submitted its combined construction and operating license application ("COL") for two Advanced Passive 1000 reactors at 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. In July 2012, BREDL petitioned for the admission of another new, late-filed contention stemming from the D.C. Circuit's order vacating the WCD. In September 2014, the ASLB denied BREDL’s request to file the new contention. 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 Bellefonte Units 3 and 4 proceeding and a motion with the ASLB seeking leave to file a new, late-filed contention stemming from 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 . Administrative Proceedings Regarding Watts Bar Unit 2 . In July 2009, SACE, the Tennessee Environmental Council, the Sierra Club, We the People, and BREDL filed a request for a hearing and petition to intervene in the NRC administrative process reviewing TVA's application for an operating license for Watts Bar Unit 2. In November 2009, the ASLB granted SACE's request for hearing, admitted two of SACE's seven contentions for hearing, and denied the request for hearing submitted on behalf of the other four petitioners. The ASLB subsequently dismissed one contention, leaving one aquatic impact contention. In July 2013, SACE filed a motion to withdraw its remaining aquatic impact contention. The ASLB granted this motion later that same month. In July 2012, SACE petitioned for the admission of another new, late-filed contention, similar to the one filed in the Bellefonte Units 3 and 4 proceeding, stemming from the D.C. Circuit's order vacating the WCD. In September 2014, the ASLB denied SACE’s request to file the contention related to the WCD and terminated the proceeding. Following the publication of the Continued Storage Rule, SACE filed a petition with the NRC seeking suspension of the issuance of a final decision in the Watts Bar Unit 2 proceeding and motions with the ASLB to reopen the record and for leave to file a new, late-filed contention stemming from 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 . In addition, in February 2015, SACE filed motions with the NRC to reopen the record and to admit a new contention relating to the expedited seismic evaluation process report for Watts Bar that TVA filed with the NRC in December 2014 as part of the Fukushima lessons-learned review process. These motions were denied in April 2015, and SACE appealed this decision to the NRC in May 2015. In April 2015, SACE filed motions with the NRC to reopen the record and to admit a new contention arguing that the environmental impact statement for Watts Bar Unit 2 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. John Sevier Fossil Plant Clean Air Act Permit . In September 2010, the Environmental Integrity Project, the Southern Environmental Law Center, and the Tennessee Environmental Council filed a petition with the EPA, requesting that the EPA Administrator object to the CAA permit issued to TVA for operation of John Sevier. Among other things, the petitioners allege that repair, maintenance, or replacement activities undertaken at John Sevier Unit 3 in 1986 triggered the Prevention of Significant Deterioration ("PSD") requirements for SO 2 and NO x . The CAA permit, issued by TDEC, remains in effect pending the disposition of the petition. TVA has now retired all four John Sevier coal-fired units, and this challenge likely will not proceed. 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 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 United States Court of Appeal for the Sixth Circuit. 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. At the request of the parties, the Administrative Law Judge ("ALJ") assigned to the matter stayed the case until October 15, 2015. 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. Johnsonville Fossil Plant NPDES Permit Administrative Appeal. SACE and TCWN filed a challenge to the NPDES permit for the Johnsonville Fossil Plant in March 2011. TDEC is the defendant in the challenge. TVA's motion to intervene was granted in August 2011. The plaintiffs voluntarily dismissed this case in February 2015. John Sevier Fossil Plant NPDES Permit Administrative Appeal. SACE and TCWN filed a challenge to the NPDES permit for John Sevier in May 2011. TDEC is the defendant in the challenge. TVA's motion to intervene was granted in August 2011. The plaintiffs voluntarily dismissed this case in February 2015. 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 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. Petitions Resulting from Japanese Nuclear Events. As a result of events that occurred at the Fukushima Daiichi Nuclear Power Plant in March 2011, petitions have been filed with the NRC which could impact TVA's nuclear program. • Petition to Immediately Suspend the Operating Licenses of GE BWR Mark I Units Pending the Full NRC Review With Independent Expert and Public Participation From Affected Emergency Planning Zone Communities Beyond Nuclear filed a petition in April 2011, requesting that the NRC take emergency enforcement action against all nuclear reactor licensees that operate units that use the General Electric Mark I BWR design. TVA uses this design at Browns Ferry Nuclear Plant ("Browns Ferry") Units 1, 2, and 3. The petition requests the NRC to take several actions, including the suspension of the operating licenses at the affected nuclear units, including Browns Ferry, until several milestones have been met. In December 2011, the NRC provided its initial response to the petition. The NRC accepted five specific requests that would apply directly or indirectly to Browns Ferry, including issues relating to spent fuel pool use and location, Mark I containment hardened vent systems and design, and backup electrical power. Each of these items was accepted for further investigation, but the requests for immediate action were rejected. The NRC ultimately denied the petition. • Petition Pursuant to 10 CFR 2.206 - Demand For Information Regarding Compliance with 10 CFR 50, Appendix A, General Design Criterion 44, Cooling Water, and 10 CFR 50.49, Environmental Qualification of Electric Equipment Important to Safety for Nuclear Power Plants A petition was filed by the Union of Concerned Scientists in July 2011, requesting that a demand for information be issued for affected licensees, including TVA with regards to Browns Ferry, describing how the facilities comply with General Design Criterion 44, Cooling Water, within Appendix A to 10 CFR Part 50, and with 10 CFR 50.49, Environmental Qualification of Electric Equipment Important to Safety for Nuclear Power Plants, for all applicable design and licensing bases events. The NRC has not yet rendered a decision regarding

Summary of Significant Accoun26

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Jun. 30, 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 ( 2015 , 2014 , 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, 2014 , and the notes thereto, which are contained in TVA's Annual Report on Form 10-K for the year ended September 30, 2014 (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 9 . 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 reclassifications have been made to the Consolidated Statement of Cash Flows for the nine months ended June 30, 2015 , in the Cash flows from operating activities section as $ 51 million previously reported as Environmental cleanup costs — Kingston ash spill — non cash and $ (65) million previously reported as Environmental cleanup costs — Kingston ash spill for the for the nine months ended June 30, 2014 , were reclassified to $ (14) million Other, net.
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 after 90 days . 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 June 30, 2015 and September 30, 2014 , for accounts receivable. Additionally, loans receivable of $ 111 million and $ 92 million at June 30, 2015 and September 30, 2014 , 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 $ 9 million at both June 30, 2015 and September 30, 2014 .
Depreciation	Depreciation Depreciation expense was $ 462 million and $ 391 million for the three months ended June 30, 2015 , and 2014 , respectively, and $ 1.2 billion and $ 1.1 billion for the nine months ended June 30, 2015 , and 2014 , respectively. In May 2015, TVA's Board approved that Widows Creek Fossil Plant ("Widows Creek") Unit 7 be retired by October 31, 2015. Management subsequently decided to retire Widows Creek Unit 7 by September 30, 2015. As a result, depreciation expense is being further accelerated over the remaining useful life. This resulted in additional accelerated depreciation expense of $81 million during both the three and nine months ended June 30, 2015. It is expected that the decision to retire Widows Creek Unit 7 by September 30, 2015 will increase depreciation expense by approximately $137 million for the remainder of 2015.
Blended Low-Enriched Uranium Program [Policy Text Block]	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 June 30, 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)	9 Months Ended
	Jun. 30, 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. The analysis to determine whether an entity is a VIE considers factors such as contracts with an entity, credit support for an entity, the adequacy of the equity investment of an entity, the extent of an entity's activities that either involve or are conducted on behalf of an investor with disproportionate voting rights, and the relationship of voting power to the amount of equity invested in an entity. A VIE is consolidated by its primary beneficiary. The primary beneficiary has both (i) the power to direct the activities that most significantly impact the entity's economic performance and (ii) the obligation to absorb losses or the right to receive benefits from the entity that could potentially be significant to the VIE. The determination of the primary beneficiary requires continual reassessment. 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. Southaven VIE On August 9, 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 scheduled amortizing, semi-annual payments due each August 15 and February 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. The sale of the SCCG notes, the membership interests in SCCG, and the SHLLC notes all closed on August 9, 2013. 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 scheduled pre-determined payments to be made to Seven States Southaven, LLC on each lease payment date by SHLLC as agreed in SHLLC’s formation documents (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. TVA participated in the design, business conduct, and financial support of SCCG and has determined that it has a direct variable interest in SCCG resulting from risk associated with the value of the Southaven CCF at the end of the lease term. Based on its analysis, TVA has determined that it is the primary beneficiary of SCCG and, as such, is required to account for the VIE on a consolidated basis. John Sevier VIE On January 17, 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 of Holdco are allocated. The membership interests held by Holdco in JSCCG were purchased with proceeds from the issuance of $ 100 million of secured notes (the “Holdco notes") and are subject to mandatory redemption pursuant to scheduled amortizing, semi-annual payments due each January 15 and July 15, with a final payment due on January 15, 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 all closed on January 17, 2012. The JSCCG notes are secured by TVA’s lease payments, and the Holdco notes are secured by Holdco's investment in, and amounts receivable from, JSCCG. TVA’s lease payments to JSCCG are equal to and payable on the same dates as JSCCG’s and Holdco’s semi-annual debt service payments. In addition to the lease payments, TVA pays administrative and miscellaneous expenses incurred by JSCCG and Holdco. Certain agreements related to this transaction contain default and acceleration provisions. Due to its participation in the design, business conduct, and credit and financial support of JSCCG and Holdco, TVA has determined that it has a variable interest in both of these entities. Based on its analysis, TVA has concluded that it is the primary beneficiary of JSCCG and Holdco and, as such, is required to account for the VIEs on a consolidated basis. Holdco’s membership interests in JSCCG are eliminated in consolidation.

Kingston Fossil Plant Ash Spi28

Kingston Fossil Plant Ash Spill (Policies)	9 Months Ended
	Jun. 30, 2015
Environmental Remediation Obligations [Abstract]
Kingston Fossil Plant Ash Spill Policy	Financial Impact TVA recorded an estimate of $ 1.1 billion for the cost of cleanup related to this event. In August 2009, TVA began using regulatory accounting treatment to defer all actual costs already incurred and expected future costs related to the ash spill. The cost is being charged to expense as it is collected in rates over 15 years , beginning October 1, 2009. Amounts spent since the event through June 30, 2015 , totaled $ 1.1 billion . The remaining estimated liability at June 30, 2015 , was $ 18 million and is included in Accounts payable and accrued liabilities and Other long-term liabilities. TVA has not included the following categories of costs in the above estimate since it has been determined that these costs are currently either not probable or not reasonably estimable: penalties (other than the penalties set out in a June 2010 TDEC order), regulatory directives, natural resources damages (other than payments required under a memorandum of agreement with TDEC and the U.S. Fish and Wildlife Service establishing a process and a method for resolving the natural resource damages claim), future lawsuits, future claims, long-term environmental impact costs, final long-term disposition of the ash processing area, and costs associated with new laws and regulations. There are certain other costs that will be incurred that have not been included in the estimate as they are appropriately accounted for in other areas of the consolidated financial statements. Associated capital asset purchases are recorded in property, plant, and equipment except for $ 12 million classified as assets held for sale and recorded in Other current assets. Ash handling and disposition costs from current plant operations are recorded in operating expenses. A portion of the dredge cell closure costs are also excluded from the estimate, as they are included in the non-nuclear ARO liability. Insurance TVA had property and excess liability insurance programs in place at the time of the Kingston ash spill. TVA pursued claims under both the property and excess liability programs and has settled all of its property insurance claims and some of its excess liability insurance claims. In April 2012, TVA initiated arbitration proceedings against the remaining excess liability insurance companies in accordance with the policies’ dispute resolution provisions. TVA is seeking recovery of certain costs incurred in the cleanup project, including the costs of removing ash from property or waters owned by the State of Tennessee, and related expenses. TVA has received insurance proceeds of $ 317 million

Asset Retirement Obligations As

Asset Retirement Obligations Asset Retirement Obligations (Policies)	9 Months Ended
	Jun. 30, 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. Decommissioning cost studies will be updated for each of TVA’s nuclear units at least every five years .

Restructuring (Tables)

Restructuring (Tables)	9 Months Ended
	Jun. 30, 2015
Restructuring and Related Activities [Abstract]
Schedule of Restructuring Reserve by Type of Cost [Table Text Block]	The table below summarizes the activity related to severance costs: Severance Cost Liability Activity Three Months Ended June 30 Nine Months Ended June 30 2015 2014 2015 2014 Severance cost liability at beginning of period $ 1 $ 32 $ 45 $ — Liabilities incurred during the period 7 21 7 56 Actual costs paid during the period (1 ) (7 ) (44 ) (10 ) Adjustments to estimate during the period — — (1 ) — Severance cost liability at end of period $ 7 $ 46 $ 7 $ 46

Accounts Receivable, Net (Table

Accounts Receivable, Net (Tables)	9 Months Ended
	Jun. 30, 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 June 30, 2015 At September 30, 2014 Power receivables $ 1,451 $ 1,576 Other receivables 125 101 Allowance for uncollectible accounts (1 ) (1 ) Accounts receivable, net $ 1,575 $ 1,676

Inventories, Net (Tables)

Inventories, Net (Tables)	9 Months Ended
	Jun. 30, 2015
Inventory, Net [Abstract]
Inventories, Net	The table below summarizes the types and amounts of TVA’s inventories: Inventories, Net At June 30, 2015 At September 30, 2014 Fuel inventory $ 513 $ 473 Materials and supplies inventory 648 616 Emission allowance inventory, net 13 13 Allowance for inventory obsolescence (48 ) (46 ) Inventories, net $ 1,126 $ 1,056

Other Long-Term Assets (Tables)

Other Long-Term Assets (Tables)	9 Months Ended
	Jun. 30, 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 June 30, 2015 At September 30, 2014 EnergyRight ® receivables $ 123 $ 123 Unamortized debt issue cost of power bonds and variable interest entities 75 68 Loans and other long-term receivables, net 108 87 Prepaid capacity payments 53 58 Restricted cash — 64 Currency swap asset, net 61 — Commodity contract derivative assets 1 — Other 110 83 Other long-term assets $ 531 $ 483

Regulatory Assets and Liabili34

Regulatory Assets and Liabilities (Tables)	9 Months Ended
	Jun. 30, 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 June 30, 2015 At September 30, 2014 Current regulatory assets Deferred nuclear generating units $ 236 $ 237 Unrealized losses on commodity derivatives 182 134 Environmental agreements 70 54 Environmental cleanup costs - Kingston ash spill 45 47 Fuel cost adjustment receivable 14 9 Other current regulatory assets 2 — Total current regulatory assets 549 481 Non-current regulatory assets Deferred pension costs and other post-retirement benefits costs 4,087 4,297 Deferred pension costs due to actions of regulator 171 — Unrealized losses on interest rate derivatives 1,028 957 Nuclear decommissioning costs 892 931 Environmental cleanup costs - Kingston ash spill 362 421 Non-nuclear decommissioning costs 720 645 Deferred nuclear generating units 1,097 1,255 Environmental agreements 63 108 Unrealized losses on commodity derivatives 81 72 Other non-current regulatory assets 286 308 Total non-current regulatory assets 8,787 8,994 Total regulatory assets $ 9,336 $ 9,475 Current regulatory liabilities Fuel cost adjustment tax equivalents $ 165 $ 182 Unrealized gains on commodity derivatives 3 2 Total current regulatory liabilities 168 184 Non-current regulatory liabilities Unrealized gains on commodity derivatives 1 — Total non-current regulatory liabilities 1 — Total regulatory liabilities $ 169 $ 184

Variable Interest Entities (Tab

Variable Interest Entities (Tables)	9 Months Ended
	Jun. 30, 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 June 30, 2015 and September 30, 2014 , as reflected in the consolidated balance sheets are as follows: Summary of Impact of VIEs on Consolidated Balance Sheets At June 30, 2015 At September 30, 2014 Current liabilities of VIE Accrued interest of VIE $ 26 $ 12 Current portion of membership interests of VIE subject to mandatory redemption 2 2 Current maturities of long-term debt of VIE 33 32 Total current liabilities of VIE 61 46 Other liabilities of VIE Membership interests of VIE subject to mandatory redemption 36 37 Long-term debt of VIE, net Long-term debt of VIE 1,263 1,279 Total liabilities of VIE $ 1,360 $ 1,362

Other Long-Term Liabilities (Ta

Other Long-Term Liabilities (Tables)	9 Months Ended
	Jun. 30, 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 June 30, 2015 At September 30, 2014 Interest rate swap liabilities $ 1,419 $ 1,348 Environmental Agreements liability 63 108 EnergyRight ® financing obligation 149 152 Membership interests of VIE subject to mandatory redemption 36 37 Commodity contract derivative liabilities 29 17 Currency swap liabilities 23 15 Commodity swap derivative liabilities 11 14 Other 289 271 Total other long-term liabilities $ 2,019 $ 1,962

Asset Retirement Obligations (T

Asset Retirement Obligations (Tables)	9 Months Ended
	Jun. 30, 2015
Asset Retirement Obligation Disclosure [Abstract]
Asset Retirement Obligation Activity	Asset Retirement Obligation Activity Nuclear Non-Nuclear Total Balance at September 30, 2014 $ 2,052 $ 1,117 $ 3,169 Settlements (ash storage areas) — (33 ) (33 ) Additional obligations — 606 606 Accretion (recorded as regulatory asset) 74 40 114 Balance at June 30, 2015 $ 2,126 $ 1,730 $ 3,856 (1 ) Note (1) The current portion of ARO in the amount of $ 180 million is included in Accounts payable and accrued liabilities at June 30, 2015 .

Debt and Other Obligations (Tab

Debt and Other Obligations (Tables)	9 Months Ended
	Jun. 30, 2015
Debt Disclosure [Abstract]
Debt Outstanding	Total debt outstanding at June 30, 2015 , and September 30, 2014 , consisted of the following: Debt Outstanding At June 30, 2015 At September 30, 2014 Short-term debt Short-term debt, net $ 2,582 $ 596 Current maturities of long-term debt of variable interest entities 33 32 Current maturities of power bonds 32 1,032 Total current debt outstanding, net 2,647 1,660 Long-term debt Long-term debt of variable interest entities 1,263 1,279 Long-term power bonds (1) 21,827 22,037 Unamortized discounts, premiums, and other (83 ) (89 ) Total long-term debt, net 23,007 23,227 Total outstanding debt $ 25,654 $ 24,887 Note (1) Includes net exchange losses from currency transactions of $ 14 million at June 30, 2015 and $ 44 million at September 30, 2014 .
Debt Securities Activity	The table below summarizes the long-term debt securities activity for the period from October 1, 2014, to June 30, 2015 : Debt Securities Activity Date Amount Interest Rate Redemptions/Maturities electronotes ® First Quarter 2015 $ 1 2.65 % electronotes ® Second Quarter 2015 42 4.20 % electronotes ® Third Quarter 2015 19 4.05 % 2009 Series A November 2014 2 2.25 % 2009 Series B December 2014 1 3.77 % 1999 Series A May 2015 38 3.96 % 2009 Series A May 2015 1 2.25 % 1998 Series D June 2015 50 3.83 % 2009 Series B June 2015 26 3.77 % 2005 Series B June 2015 1,000 4.38 % Total redemptions/maturities of power bonds 1,180 Variable interest entities Second Quarter 2015 15 4.29 % Total redemptions/maturities of debt $ 1,195 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 or three long-term credit facilities: Summary of Long-Term Credit Facilities At June 30, 2015 (in billions) Maturity Date Facility Limit Letters of Credit Outstanding Cash Borrowings Availability December 2017 $ 1.0 $ 0.3 $ — $ 0.7 April 2018 0.5 0.5 — — June 2020 1.0 0.3 — 0.7 Total $ 2.5 $ 1.1 $ — $ 1.4

Risk Management Activities an39

Risk Management Activities and Derivative Transactions (Tables)	9 Months Ended
	Jun. 30, 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 June 30 Nine Months Ended June 30 Derivatives in Cash Flow Hedging Relationship Objective of Hedge Transaction Accounting for Derivative Hedging Instrument 2015 2014 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 $ 62 $ 1 $ (12 ) $ 23 Summary of Derivative Instruments That Receive Hedge Accounting Treatment (part 2) Amount of Gain (Loss) Reclassified from OCI to Interest Expense Three Months Ended Nine Months Ended Derivatives in Cash Flow Hedging Relationship 2015 2014 2015 2014 Currency swaps $ 53 $ 26 $ (31 ) $ 55 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 $ 91 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 June 30 ( 1) Nine Months Ended June 30 (1) Derivative Type Objective of Derivative Accounting for Derivative Instrument 2015 2014 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 until settlement, at which time the gains/losses are recognized in gain/loss on derivative contracts. $ — $ — $ — $ — 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. (30 ) (6 ) (69 ) (29 ) 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 and nine months ended June 30, 2015 and 2014 .
Fair Value of TVA Derivatives	Fair Values of TVA Derivatives At June 30, 2015 At September 30, 2014 Derivatives that Receive Hedge Accounting Treatment Balance Balance Sheet Presentation Balance Balance Sheet Presentation Currency swaps £200 million Sterling $ (23 ) Other long-term liabilities $ (15 ) Other long-term liabilities £250 million Sterling 49 Other long-term assets 56 Other long-term assets £150 million Sterling 12 Other long-term assets 8 Other long-term assets At June 30, 2015 At September 30, 2014 Derivatives that Do Not Receive Hedge Accounting Treatment Balance Balance Sheet Presentation Balance Balance Sheet Presentation Interest rate swaps $1.0 billion notional (1,034 ) Other long-term liabilities (987 ) Other long-term liabilities $476 million notional (373 ) Other long-term liabilities (349 ) Other long-term liabilities $42 million notional (12 ) Other long-term liabilities (12 ) Other long-term liabilities Commodity contract derivatives (125 ) Other current assets $2; Other long-term assets $1; Other long-term liabilities $(29); Accounts payable and accrued liabilities $(99) (96 ) Other current assets $1; Other long-term liabilities $(17); Accounts payable and accrued liabilities $(80) FTP Derivatives under FTP (1) (125 ) Other current assets $(91); Other long-term liabilities $(11); Accounts payable and accrued liabilities $(23) (103 ) Other current assets $(69); Other long-term liabilities $(14); Accounts payable and accrued liabilities $(20) Note (1) Fair values of certain derivatives under the FTP that were in net liability positions totaling $ 91 million and $ 69 million at June 30, 2015 and September 30, 2014 , 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 June 30, 2015 : Currency Swaps Outstanding At June 30, 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 June 30, 2015 At September 30, 2014 Number of Contracts Notional Amount Fair Value (MtM) Number of Contracts Notional Amount Fair Value ( MtM ) Coal contract derivatives 13 22 million tons $ (128 ) 24 31 million tons $ (86 ) Natural gas contract derivatives 36 146 million mmBtu $ 3 46 62 million mmBtu $ (10 )
Derivatives Under Financial Trading Program	Derivatives Under Financial Trading Program At June 30, 2015 At September 30, 2014 Notional Amount Fair Value (MtM) (in millions) Notional Amount Fair Value (MtM) (in millions) Natural gas (in mmBtu) Swap contracts 63,835,000 $ (125 ) 102,227,500 $ (103 ) 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)	Financial Trading Program Unrealized Gains (Losses) At June 30, 2015 At September 30, 2014 FTP unrealized gains (losses) deferred as regulatory liabilities (assets) Natural gas $ (125 ) $ (103 )
Financial Trading Program Realized Gains (Losses)	Financial Trading Program Realized Gains (Losses) For the Three Months Ended June 30 For the Nine Months Ended June 30 2015 2014 2015 2014 Decrease (increase) in fuel expense Natural gas $ (24 ) $ (5 ) $ (56 ) $ (23 ) Fuel oil/crude oil — — 1 2 Financial Trading Program Realized Gains (Losses) For the Three Months Ended For the Nine Months Ended 2015 2014 2015 2014 Decrease (increase) in purchased power expense Natural gas $ (6 ) $ (1 ) $ (14 ) $ (9 )
Offsetting of Derivative Assets and Liabilities	The amounts of TVA's derivative instruments as reported in the Consolidated Balance Sheets as of June 30, 2015 , and September 30, 2014 , are shown in the table below: As of June 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) $ 61 $ — $ 61 Commodity derivatives under FTP 55 (55 ) — Total derivatives subject to master netting or similar arrangement 116 (55 ) 61 Total derivatives not subject to master netting or similar arrangement 3 — 3 Total $ 119 $ (55 ) $ 64 Liabilities Currency swap(s) (4) $ 23 $ — $ 23 Interest rate swaps (4) 1,419 — 1,419 Commodity derivatives under FTP 180 (146 ) 34 Total derivatives subject to master netting or similar arrangement 1,622 (146 ) 1,476 Total derivatives not subject to master netting or similar arrangement 128 — 128 Total $ 1,750 $ (146 ) $ 1,604 As of September 30, 2014 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) $ 64 $ (64 ) $ — Commodity derivatives under FTP 51 (51 ) — Total derivatives subject to master netting or similar arrangement 115 (115 ) — Total derivatives not subject to master netting or similar arrangement 1 — 1 Total $ 116 $ (115 ) $ 1 Liabilities Currency swap(s) (4) $ 15 $ — $ 15 Interest rate swaps (4) 1,348 — 1,348 Commodity derivatives under FTP 154 (120 ) 34 Total derivatives subject to master netting or similar arrangement 1,517 (120 ) 1,397 Total derivatives not subject to master netting or similar arrangement 97 — 97 Total $ 1,614 $ (120 ) $ 1,494 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 Consolidated Balance Sheets. (3) At June 30, 2015 , securities of approximately $ 9 million were 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 and $1.0 billion were posted as collateral at June 30, 2015 and September 30, 2014 , respectively, 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. At June 30, 2015 , TVA held no cash collateral in excess of collateral requirements and at September 30, 2014 , TVA held $19 million of cash collateral in excess of collateral requirements that was classified in Restricted cash and investments with a corresponding obligation recorded in Accounts payable and accrued liabilities in the same amount.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Jun. 30, 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 June 30 For the Nine Months Ended June 30 Financial Statement Presentation 2015 2014 2015 2014 SERP Other income (expense) $ — $ 1 $ — $ 2 LTDCP Other income (expense) — — (1 ) — NDT Regulatory asset (19 ) 36 15 72 ART Regulatory asset (3 ) 9 12 27
Fair Value Measurements	Fair Value Measurements At June 30, 2015 Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total Assets Investments Equity securities $ 181 $ — $ — $ 181 Debt securities U.S. government corporations and agencies 59 7 — 66 Corporate debt securities — 336 — 336 Residential mortgage-backed securities — 16 — 16 Commercial mortgage-backed securities — 5 — 5 Collateralized debt obligations — 29 — 29 Private partnerships — — 238 238 Commingled funds (1) Equity security commingled funds 44 942 — 986 Debt security commingled funds 44 178 — 222 Total investments 328 1,513 238 2,079 Currency swap(s) (2) — 61 — 61 Commodity contract derivatives — — 3 3 Commodity derivatives under FTP (2) Swap contracts — — — — Total $ 328 $ 1,574 $ 241 $ 2,143 Quoted Prices in Active Markets for Identical Liabilities (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total Liabilities Currency swap(s) (2) $ — $ 23 $ — $ 23 Interest rate swaps — 1,419 — 1,419 Commodity contract derivatives — — 128 128 Commodity derivatives under FTP (2) Swap contracts — 34 — 34 Total $ — $ 1,476 $ 128 $ 1,604 Notes (1) Commingled funds represent investment funds comprising multiple individual financial instruments and are classified in the table based on their existing investment portfolio as of the measurement date. Commingled funds primarily composed of one class of security are classified in that category. (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 any cash collateral received from or paid to the counterparty, to the extent such amount is not recorded in Accounts payable and accrued liabilities. See Note 15 — Offsetting of Derivative Assets and Liabilities . Fair Value Measurements At September 30, 2014 Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total Assets Investments Equity securities $ 162 $ — $ — $ 162 Debt securities U.S. government corporations and agencies 46 39 — 85 Corporate debt securities — 290 — 290 Residential mortgage-backed securities — 14 — 14 Commercial mortgage-backed securities — 7 — 7 Collateralized debt obligations — 29 — 29 Private partnerships — — 214 214 Commingled funds (1) Equity security commingled funds 40 903 — 943 Debt security commingled funds 61 176 — 237 Total investments 309 1,458 214 1,981 Currency swap(s) (2) — — — — Commodity contract derivatives — — 1 1 Commodity derivatives under FTP (2) Swap contracts — — — — Total $ 309 $ 1,458 $ 215 $ 1,982 Quoted Prices in Active Markets for Identical Liabilities (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total Liabilities Currency swap(s) (2) $ — $ 15 $ — $ 15 Interest rate swaps — 1,348 — 1,348 Commodity contract derivatives — — 97 97 Commodity derivatives under FTP (2) Swap contracts — 34 — 34 Total $ — $ 1,397 $ 97 $ 1,494 Notes (1) Commingled funds represent investment funds comprising multiple individual financial instruments and are classified in the table based on their existing investment portfolio as of the measurement date. Commingled funds primarily composed of one class of security are classified in that category. (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 any cash collateral received from or paid to the counterparty. See Note 15 — Offsetting of Derivative Assets and Liabilities . 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 June 30, 2015 , and September 30, 2014 .
Fair Value Measurements Using Significant Unobservable Inputs	The following table presents a reconciliation of all assets and liabilities measured at fair value on a recurring basis using significant unobservable inputs (Level 3): Fair Value Measurements Using Significant Unobservable Inputs For the Three Months Ended For the Nine Months Ended Private Partnerships Commodity Contract Derivatives Private Partnerships Commodity Contract Derivatives Balance at beginning of period $ 180 $ (131 ) $ 159 $ (140 ) Purchases 7 — 23 — Issuances — — — — Sales (6 ) — (7 ) — Settlements — — — — Net unrealized gains (losses) deferred as regulatory assets and liabilities 7 (15 ) 13 (6 ) Balance at June 30, 2014 $ 188 $ (146 ) $ 188 $ (146 ) Balance at beginning of period $ 223 $ (149 ) $ 214 $ (96 ) Purchases 11 — 21 — Issuances — — — — Sales (5 ) — (12 ) — Settlements — — — — Net unrealized gains (losses) deferred as regulatory assets and liabilities 9 24 15 (29 ) Balance at June 30, 2015 $ 238 $ (125 ) $ 238 $ (125 )
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 June 30 2015 Valuation Technique(s) Unobservable Inputs Range Assets Commodity contract derivatives $ 3 Pricing model Coal supply and demand 0.8 - 1.0 billion tons/year Long-term market prices $10.08 - $103.41/ton Liabilities Commodity contract derivatives $ 128 Pricing model Coal supply and demand 0.8 - 1.0 billion tons/year Long-term market prices $10.08 - $103.41/ton Quantitative Information about Level 3 Fair Value Measurements Fair Value at September 30 2014 Valuation Technique(s) Unobservable Inputs Range Assets Commodity contract derivatives $ 1 Discounted cash flow Credit risk 2 - 5 % (1) Pricing model Coal supply and demand 1.0 - 1.1 billion tons/year Long-term market prices $11.24 - $67.07/ton Liabilities Commodity contract derivatives $ 97 Pricing model Coal supply and demand 1.0 - 1.1 billion tons/year Long-term market prices $11.24 - $67.07/ton Note (1) Applies to two contracts.
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 June 30, 2015 , and September 30, 2014 , were as follows: Estimated Values of Financial Instruments Not Recorded at Fair Value At June 30, 2015 At September 30, 2014 Valuation Classification Carrying Amount Fair Value Carrying Amount Fair Value EnergyRight ® receivables (including current portion) Level 2 $ 155 $ 163 $ 156 $ 166 Loans and other long-term receivables, net (including current portion) Level 2 $ 111 $ 99 $ 92 $ 81 EnergyRight ® financing obligation (including current portion) Level 2 $ 186 $ 209 $ 190 $ 215 Unfunded loan commitments Level 2 $ — $ 20 $ — $ 18 Membership interest of variable interest entity subject to mandatory redemption (including current portion) Level 2 $ 38 $ 47 $ 39 $ 50 Long-term outstanding power bonds (including current maturities), net Level 2 $ 21,776 $ 25,134 $ 22,980 $ 26,889 Long-term debt of variable interest entities (including current maturities) Level 2 $ 1,296 $ 1,392 $ 1,311 $ 1,425

Other Income (Expense), Net (Ta

Other Income (Expense), Net (Tables)	9 Months Ended
	Jun. 30, 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 For the Nine Months Ended 2015 2014 2015 2014 Interest income $ 6 $ 6 $ 18 $ 17 External services 3 3 9 15 Gains (losses) on investments — 2 3 4 Miscellaneous (1 ) (1 ) (5 ) 1 Total other income (expense), net $ 8 $ 10 $ 25 $ 37

Benefit Plans (Tables)

Benefit Plans (Tables)	9 Months Ended
	Jun. 30, 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 and nine months ended June 30, 2015 , and 2014 , were as follows: Components of TVA’s Benefit Plans For the Three Months Ended June 30 For the Nine Months Ended June 30 Pension Benefits Other Post-Retirement Benefits Pension Benefits Other Post-Retirement Benefits 2015 2014 2015 2014 2015 2014 2015 2014 Service cost $ 32 $ 33 $ 4 $ 5 $ 97 $ 98 $ 12 $ 14 Interest cost 135 139 7 8 405 418 22 24 Expected return on plan assets (110 ) (109 ) — — (328 ) (326 ) — — Amortization of prior service credit (5 ) (5 ) (2 ) (2 ) (16 ) (16 ) (5 ) (5 ) Recognized net actuarial loss 75 71 3 3 225 214 7 8 Total net periodic benefit cost as actuarially determined 127 129 12 14 383 388 36 41 Amount capitalized due to actions of regulator (57 ) — — — (171 ) — — — Total net periodic benefit cost $ 70 $ 129 $ 12 $ 14 $ 212 $ 388 $ 36 $ 41

Summary of Significant Accoun43

Summary of Significant Accounting Policies General and Basis of Presentation (Details) People in Millions, $ in Millions	3 Months Ended			9 Months Ended
	Sep. 30, 2015USD ($)	Jun. 30, 2015USD ($)variable_interest_entitiesPeople	Jun. 30, 2014USD ($)	Jun. 30, 2015USD ($)variable_interest_entitiesPeople	Jun. 30, 2014USD ($)	Sep. 30, 2014USD ($)
General and Basis of Presentation
Population of TVA's service area | People		9		9
Amount of appropriation investment that was be repaid						$ 1,000
Number of variable interest entities | variable_interest_entities		3		3
Reclassification from Environmental cleanup costs-Kingston ash spill-non cash to Other, net				$ 51
Reclassification from Environmental cleanup costs-Kingston ash spill to Other, net				(65)
Reclassification to Other, net from Environmental cleanup costs-Kingston ash spill-non cash and Environmental cleanup costs-Kingston ash spill				$ (14)
Period of time for customers to fulfill payment arrangements				90 days
Allowance for uncollectible accounts, accounts receivable		$ 1		$ 1		1
Loans receivable		99		99		81
Loans receivable, allowance		9		9		$ 9
Depreciation expense		462	$ 391	1,200	$ 1,100
Accelerated depreciation		81		81
Total possible amount of payments		162		162
Payments attributable to BLEU fuel program		131		131
BLEU fuel obligation		$ 12		$ 12
Scenario, Forecast [Member]
General and Basis of Presentation
Accelerated depreciation	$ 137

Impact of New Accounting Stan44

Impact of New Accounting Standards and Interpretations Impact of New Accounting Standards and Interpretations (Details) - USD ($) $ in Millions	Jun. 30, 2015	Sep. 30, 2014
Other long-term assets
Unamortized debt issue cost of power bonds and variable interest entities	$ 75	$ 68

Restructuring (Details)

Restructuring (Details) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Jun. 30, 2015USD ($)	Jun. 30, 2014USD ($)	Jun. 30, 2015USD ($)	Jun. 30, 2014USD ($)	Sep. 30, 2015	Sep. 30, 2014USD ($)	Mar. 31, 2015USD ($)	Mar. 31, 2014USD ($)	Sep. 30, 2013USD ($)
Restructuring Cost and Reserve [Line Items]
Expected increase (decrease) in operation and maintenance expense			$ (500)
Number of positions eliminated						2,000
Severance cost liability	$ 7	$ 46	7	$ 46		$ 45	$ 1	$ 32	$ 0
Liabilities incurred during the period	7	21	7	56
Actual costs paid during the period	(1)	(7)	(44)	(10)
Adjustments to estimate during the period	$ 0	$ 0	$ (1)	$ 0
Scenario, Forecast [Member]
Restructuring Cost and Reserve [Line Items]
Number of positions eliminated					200

Accounts Receivable, Net (Detai

Accounts Receivable, Net (Details) - USD ($) $ in Millions	Jun. 30, 2015	Sep. 30, 2014
Accounts Receivable, Net
Power receivables	$ 1,451	$ 1,576
Other receivables	125	101
Allowance for uncollectible accounts	(1)	(1)
Accounts receivable, net	$ 1,575	$ 1,676

Inventories, Net (Details)

Inventories, Net (Details) - USD ($) $ in Millions	Jun. 30, 2015	Sep. 30, 2014
Inventories, Net
Fuel inventory	$ 513	$ 473
Materials and supplies inventory	648	616
Emission allowance inventory, net	13	13
Allowance for inventory obsolescence	(48)	(46)
Inventories, net	$ 1,126	$ 1,056

Acquisition (Details)

Acquisition (Details) - Apr. 14, 2015 $ in Millions	USD ($)Megawatts
Business Acquisition, Transaction Costs	$ 342
Megawatts | Megawatts	700
Completed Plant
Business Acquisition, Transaction Costs	$ 333
Other long-term assets
Business Acquisition, Transaction Costs	6
Inventories
Business Acquisition, Transaction Costs	$ 3

Other Long-Term Assets (Details

Other Long-Term Assets (Details) - USD ($) $ in Millions		9 Months Ended
		Jun. 30, 2015	Sep. 30, 2014
Other Long-Term Assets
EnergyRight receivables		$ 163	$ 166
Currency swap asset, net	[1]	61	0
Total other long-term assets		$ 531	483
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	123
Unamortized debt issue cost of power bonds and variable interest entities		75	68
Loans and other long-term receivables, net		108	87
Prepaid capacity payments		53	58
Restricted cash		0	64
Currency swap asset, net		61	0
Commodity contract derivative assets		1	0
Other		110	83
Accounts Receivable [Member]
Other Long-Term Assets
EnergyRight receivables		$ 32	$ 33
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 any cash collateral received from or paid to the counterparty, to the extent such amount is not recorded in Accounts payable and accrued liabilities. See Note 15 — Offsetting of Derivative Assets and Liabilities.

Regulatory Assets and Liabili50

Regulatory Assets and Liabilities (Details) - USD ($) $ in Millions	Jun. 30, 2015	Sep. 30, 2014
Regulatory Assets and Liabilities
Current regulatory assets	$ 549	$ 481
Non-current regulatory assets	8,787	8,994
Regulatory assets	9,336	9,475
Current regulatory liabilities	168	184
Non-current regulatory liabilities	1	0
Regulatory liabilities	169	184
Fuel cost adjustment tax equivalents
Regulatory Assets and Liabilities
Current regulatory liabilities	165	182
Unrealized gains/losses on commodity derivatives
Regulatory Assets and Liabilities
Current regulatory liabilities	3	2
Non-current regulatory liabilities	1	0
Deferred nuclear generating units
Regulatory Assets and Liabilities
Current regulatory assets	236	237
Non-current regulatory assets	1,097	1,255
Unrealized gains/losses on commodity derivatives
Regulatory Assets and Liabilities
Current regulatory assets	182	134
Non-current regulatory assets	81	72
Environmental agreements
Regulatory Assets and Liabilities
Current regulatory assets	70	54
Non-current regulatory assets	63	108
Environmental cleanup costs - Kingston ash spill
Regulatory Assets and Liabilities
Current regulatory assets	45	47
Non-current regulatory assets	362	421
Fuel cost adjustment receivable/liability
Regulatory Assets and Liabilities
Current regulatory assets	14	9
Other current regulatory assets
Regulatory Assets and Liabilities
Current regulatory assets	2	0
Deferred pension costs and other post-retirement benefits costs
Regulatory Assets and Liabilities
Non-current regulatory assets	4,087	4,297
Deferred pension costs due to actions of regulator
Regulatory Assets and Liabilities
Non-current regulatory assets	171	0
Unrealized losses on interest rate derivatives
Regulatory Assets and Liabilities
Non-current regulatory assets	1,028	957
Nuclear decommissioning costs
Regulatory Assets and Liabilities
Non-current regulatory assets	892	931
Non-nuclear decommissioning costs
Regulatory Assets and Liabilities
Non-current regulatory assets	720	645
Other non-current regulatory assets
Regulatory Assets and Liabilities
Non-current regulatory assets	$ 286	$ 308

Variable Interest Entities Vari

Variable Interest Entities Variable Interest Entities (Details) - USD ($) $ in Millions	Jun. 30, 2015	Sep. 30, 2014	Aug. 09, 2013	Jan. 17, 2012
VIE Financing
Membership interests of VIE subject to mandatory redemption	$ 47	$ 50	$ 40
Liabilities
Total liabilities of VIE	1,360	1,362		$ 1,000
SCCG
VIE Financing
Face amount			$ 360
JSCCG
VIE Financing
Face amount				900
Holdco
VIE Financing
Face amount				$ 100
Accrued interest of VIE
Liabilities
Total liabilities of VIE	26	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	32
Total current liabilities of VIE
Liabilities
Total liabilities of VIE	61	46
Membership interests of VIE subject to mandatory redemption
Liabilities
Total liabilities of VIE	36	37
Long-term debt of VIE
Liabilities
Total liabilities of VIE	$ 1,263	$ 1,279

Kingston Fossil Plant Ash Spi52

Kingston Fossil Plant Ash Spill (Details) Cubic_yards in Millions, $ in Millions	9 Months Ended	36 Months Ended
	Jun. 30, 2015USD ($)	Mar. 31, 2015USD ($)	Dec. 31, 2008Dredge_cellsCubic_yards
Kingston Fossil Plant Ash Spill
Number of dredge cells that failed | Dredge_cells			1
Cubic yards of water and coal fly ash that flowed out of the cell | Cubic_yards			5
Total recorded estimate of Kingston cleanup costs	$ 1,100
Period collected in rates	15 years
Kingston cleanup amounts spent to date	$ 1,100
Remaining estimated Kingston liability	18
Assets held for sale	$ 12
Kingston insurance recoveries		$ 317

Other Long-Term Liabilities (De

Other Long-Term Liabilities (Details) - USD ($) $ in Millions		9 Months Ended
		Jun. 30, 2015	Sep. 30, 2014	Aug. 09, 2013
Other Long-Term Liabilities
Interest rate swap liabilities		$ 1,419	$ 1,348
EnergyRight® financing obligation		209	215
Currency swap liabilities	[1]	23	15
Total other long-term liabilities		2,019	1,962
Percentage of membership interests issued				100.00%
Membership interests of VIE subject to mandatory redemption, interest rate, stated percentage				7.00%
Membership interests of VIE subject to mandatory redemption		$ 47	50	$ 40
SCCG balloon payment				$ 4
Energy Right Program
Other Long-Term Liabilities
Number of days in default		180 days
Other Noncurrent Liabilities [Member]
Other Long-Term Liabilities
Interest rate swap liabilities		$ 1,419	1,348
Environmental agreements liability		63	108
EnergyRight® financing obligation		149	152
Membership interests of VIE subject to mandatory redemption		36	37
Commodity contract derivative liabilities		29	17
Currency swap liabilities		23	15
Commodity swap derivative liabilities		11	14
Other		289	271
Accounts payable and accrued liabilities
Other Long-Term Liabilities
EnergyRight® financing obligation		37	38
Current portion of membership interests of VIE subject to mandatory redemption		$ 2	$ 2
Minimum | Energy Right Program
Other Long-Term Liabilities
EnergyRight loan term		5 years
Maximum | Energy Right Program
Other Long-Term Liabilities
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 any cash collateral received from or paid to the counterparty, to the extent such amount is not recorded in Accounts payable and accrued liabilities. See Note 15 — Offsetting of Derivative Assets and Liabilities.

Asset Retirement Obligations (D

Asset Retirement Obligations (Details) - Jun. 30, 2015 - USD ($) $ in Millions		Total
Asset Retirement Obligations
Asset retirement obligations, period increase (decrease)		$ 687
Decommissioning study update - ARO nuclear		5 years
Accretion expense		$ 33
Balance at September 30, 2014	[1]	3,169
Settlements (ash storage areas)	[1]	(33)
Additional obligations		606
Accretion (recorded as regulatory asset)	[1]	114
Balance at June 30, 2015	[1]	3,856
Current portion of ARO		180
Nuclear
Asset Retirement Obligations
Balance at September 30, 2014	[1]	2,052
Settlements (ash storage areas)	[1]	0
Additional obligations	[1]	0
Accretion (recorded as regulatory asset)	[1]	74
Balance at June 30, 2015	[1]	2,126
Non-nuclear
Asset Retirement Obligations
Balance at September 30, 2014	[1]	1,117
Settlements (ash storage areas)	[1]	(33)
Additional obligations		606
Accretion (recorded as regulatory asset)	[1]	40
Balance at June 30, 2015	[1]	1,730
EPA Ruling | Non-nuclear
Asset Retirement Obligations
Additional obligations		539
Coal-fired obligations | Non-nuclear
Asset Retirement Obligations
Additional obligations		60
Plant acquisition | Non-nuclear
Asset Retirement Obligations
Additional obligations		$ 7
[1]	The current portion of ARO in the amount of $180 million is included in Accounts payable and accrued liabilities at June 30, 2015.

Debt and Other Obligations Debt

Debt and Other Obligations Debt Outstanding (Details) - USD ($) $ in Millions		9 Months Ended	12 Months Ended
		Jun. 30, 2015	Sep. 30, 2014
Debt Instrument
Foreign Currency Transaction Gain (Loss), before Tax		$ (14)	$ (44)
Short-term debt
Short-term debt, net		2,582	596
Current maturities of long-term debt of variable interest entities		33	32
Current maturities of power bonds		32	1,032
Total current debt outstanding, net		2,647	1,660
Long-term debt
Long-term debt of variable interest entities		1,263	1,279
Long-term power bonds	[1]	21,827	22,037
Unamortized discounts, premiums and other		(83)	(89)
Total long-term debt, net		23,007	23,227
Total outstanding debt		$ 25,654	$ 24,887
[1]	Includes net exchange losses from currency transactions of $14 million at June 30, 2015 and $44 million at September 30, 2014.

Debt and Other Obligations De56

Debt and Other Obligations Debt Securities Activity (Details) - USD ($) $ in Millions		1 Months Ended				3 Months Ended			9 Months Ended
		Jun. 30, 2015	May. 31, 2015	Dec. 31, 2014	Nov. 30, 2014	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Jun. 30, 2015	Jun. 30, 2014
Debt Instrument
Redemptions/maturities of power bonds									$ 1,180	$ 363
Redemptions/maturities of variable interest entities									15	$ 15
Total redemptions/maturities of debt									$ 1,195
electronotes
Debt Instrument
Redemptions/maturities of power bonds	[1]					$ 19	$ 42	$ 1
Interest rate		4.05%		2.65%		4.05%	4.20%	2.65%	4.05%
2009 Series A
Debt Instrument
Redemptions/maturities of power bonds	[1]		$ 1		$ 2
Interest rate			2.25%		2.25%
1998 Series D
Debt Instrument
Redemptions/maturities of power bonds	[1]	$ 50
Interest rate		3.83%				3.83%			3.83%
2009 Series B
Debt Instrument
Redemptions/maturities of power bonds	[1]	$ 26		$ 1
Interest rate		3.77%		3.77%		3.77%		3.77%	3.77%
2005 Series B
Debt Instrument
Redemptions/maturities of power bonds	[1]	$ 1,000
Interest rate		4.38%				4.38%			4.38%
1999 Series A
Debt Instrument
Redemptions/maturities of power bonds	[1]		$ 38
Interest rate			3.96%
Debt of variable interest entities
Debt Instrument
Redemptions/maturities of variable interest entities	[1]						$ 15
Interest rate of variable interest entities							4.29%
Total
Debt Instrument
Percent of par value		100.00%				100.00%			100.00%
[1]	All redemptions were at 100 percent of par.

Debt and Other Obligations Cred

Debt and Other Obligations Credit Facility Agreements (Details) $ in Millions	Jun. 30, 2015USD ($)Credit_facilities	Sep. 30, 2014USD ($)
Line of Credit [Member]
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
December 2017 Credit Facility	$ 1,000
April 2018 Credit Facility	500
June 2020 Credit Facility	1,000
Current borrowing capacity for credit facilities	2,500
Cash Borrowings-December 2017 Credit Facility	0
Cash Borrowings-April 2018 Credit Facility	0
Cash Borrowings-June 2020 Credit Facility	0
Total Cash Borrowings for Credit Facilities	0	$ 0
Remaining Availability, December 2017 Credit Facility	700
Remaining Availability, April 2018 Credit Facility	0
Remaining Availability, June 2020 Credit Facility	700
Total Remaining Availability for Credit Facilities	1,400
Letter of Credit
Credit Facility Agreements
Letter of Credit Outstanding, December 2017 Credit Facility	300
Letter of Credit Outstanding, April 2018 Credit Facility	500
Letter of Credit Outstanding, June 2020 Credit Facility	300
Amount of letters of credit outstanding for credit facilities	$ 1,100	$ 1,000

Debt and Other Obligations Leas

Debt and Other Obligations Lease/Leaseback Obligations (Details) $ in Millions	12 Months Ended
	Sep. 30, 2003USD ($)Units	Jun. 30, 2015USD ($)	Sep. 30, 2014USD ($)
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		$ 617	$ 691

Accumulated Other Comprehensi59

Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Equity [Abstract]
Reclassification to earnings from cash flow hedges	[1]	$ 53	$ 26	$ (31)	$ 55
[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 $91 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 an60

Risk Management Activities and Derivative Transactions Derivative Instruments That Receive Hedge Accounting Treatment (Details) - USD ($)		3 Months Ended		9 Months Ended
		Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Summary of Derivative Instruments That Receive Hedge Accounting Treatment
Net unrealized gain (loss) on cash flow hedges		$ 62,000,000	$ 1,000,000	$ (12,000,000)	$ 23,000,000
Reclassification to earnings from cash flow hedges	[1]	53,000,000	26,000,000	(31,000,000)	55,000,000
Ineffective portion excluded from testing		$ 0	$ 0	0	$ 0
Reclassification to earnings from cash flow hedges in the next 12 months				$ 91,000,000
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 $91 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 an61

Risk Management Activities and Derivative Transactions Derivative Instruments That Do Not Receive Hedge Accounting Treatment (Details)		3 Months Ended			9 Months Ended
		Jun. 30, 2015USD ($)	Jun. 30, 2014USD ($)		Jun. 30, 2015USD ($)	Jun. 30, 2014USD ($)		Sep. 30, 2014USD ($)
Derivative
Change in Unrealized gains (losses) on Interest Rate Derivatives		$ 278,000,000	$ (65,000,000)		$ (71,000,000)	$ (90,000,000)
Amount of gain (loss) recognized in income on derivatives		0			0
Unrealized gain (loss) on derivatives		0	0		0	0
Interest Rate Swap
Derivative
Amount of gain (loss) recognized in income on derivatives	[1]	0	0		0	0
Commodity Contract Derivatives
Derivative
Amount of gain (loss) recognized in income on derivatives		0	0	[1]	0	0	[1]
Fair value		(125,000,000)			(125,000,000)			$ (96,000,000)
Commodity derivatives under the financial trading program
Derivative
Amount of gain (loss) recognized in income on derivatives		(30,000,000)	$ (6,000,000)	[1]	(69,000,000)	$ (29,000,000)	[1]
Fair value	[2]	$ (125,000,000)			$ (125,000,000)			$ (103,000,000)
Coal Contract Derivatives
Derivative
Number of contracts		13			13			24
Notional amount		22,000,000			22,000,000			31,000,000
Fair value		$ (128,000,000)			$ (128,000,000)			$ (86,000,000)
Natural Gas
Derivative
Number of contracts		36			36			46
Notional amount		146,000,000			146,000,000			62,000,000
Fair value		$ 3,000,000			$ 3,000,000			$ (10,000,000)
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		(125,000,000)			$ (125,000,000)			(103,000,000)
Letter of Credit
Derivative
Amount of letters of credit outstanding		$ 1,100,000,000			$ 1,100,000,000			$ 1,000,000,000
[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 and nine months ended June 30, 2015 and 2014.
[2]	Fair values of certain derivatives under the FTP that were in net liability positions totaling $91 million and $69 million at June 30, 2015 and September 30, 2014, 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 an62

Risk Management Activities and Derivative Transactions Fair Values of TVA Derivatives (Details) - USD ($) $ in Millions		Jun. 30, 2015	Sep. 30, 2014
Derivatives, Fair Value
Gross amounts of recognized liabilities		$ 1,622	$ 1,517
200 million Sterling currency swap | Other long-term liabilities
Derivatives, Fair Value
Fair value		(23)	(15)
250 million Sterling currency swap | Other long-term assets
Derivatives, Fair Value
Fair value		49	56
150 million Sterling currency swap | Other long-term assets
Derivatives, Fair Value
Fair value		12	8
$1.0 billion notional interest rate swap | Other long-term liabilities
Derivatives, Fair Value
Fair value		(1,034)	(987)
$476 million notional interest rate swap | Other long-term liabilities
Derivatives, Fair Value
Fair value		(373)	(349)
$42 million notional interest rate swap | Other long-term liabilities
Derivatives, Fair Value
Fair value		(12)	(12)
Commodity contract derivatives
Derivatives, Fair Value
Fair value		(125)	(96)
Commodity contract derivatives | Other long-term assets
Derivatives, Fair Value
Fair value		1
Commodity contract derivatives | Other current assets
Derivatives, Fair Value
Fair value		2	1
Commodity contract derivatives | Other long-term liabilities
Derivatives, Fair Value
Fair value		(29)	(17)
Commodity contract derivatives | Accounts payable and accrued liabilities
Derivatives, Fair Value
Fair value		(99)	(80)
Commodity derivatives under FTP
Derivatives, Fair Value
Fair value	[1]	(125)	(103)
Commodity derivatives under FTP | Other current assets
Derivatives, Fair Value
Gross amounts of recognized liabilities		91	69
Fair value		(91)	(69)
Commodity derivatives under FTP | Other long-term liabilities
Derivatives, Fair Value
Fair value		(11)	(14)
Commodity derivatives under FTP | Accounts payable and accrued liabilities
Derivatives, Fair Value
Fair value		$ (23)	$ (20)
[1]	Fair values of certain derivatives under the FTP that were in net liability positions totaling $91 million and $69 million at June 30, 2015 and September 30, 2014, 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 an63

Risk Management Activities and Derivative Transactions Currency Swaps Outstanding (Details) - Jun. 30, 2015 - GBP (£) £ in Millions	Total
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 an64

Risk Management Activities and Derivative Transactions Derivatives Under FTP (Details) $ in Millions		9 Months Ended
		Jun. 30, 2015USD ($)	Sep. 30, 2014USD ($)
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
Swap contracts
Derivative
Remaining terms		3 years
Natural Gas Swap
Derivative
Fair value	[1]	$ (125)	$ (103)
Notional amount	[1]	63,835,000	102,227,500
Coal Contract Derivatives
Derivative
Fair value		$ 0	$ 0
Futures Contracts
Derivative
Fair value		0
Options Contract
Derivative
Fair value		$ 0
[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 an65

Risk Management Activities and Derivative Transactions Derivatives Under Financial Trading Program (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Sep. 30, 2014
Natural Gas Swap
Derivative
Fair value	[1]	$ (125)		$ (125)		$ (103)
Natural Gas Total Contracts
Derivative
Fair value		(125)		(125)		(103)
Decrease (increase) in fuel expense		(24)	$ (5)	(56)	$ (23)
Decrease (increase) in purchased power expense		(6)	(1)	(14)	(9)
Fuel Oil and Crude Oil Total Contracts
Derivative
Decrease (increase) in fuel expense		0	$ 0	1	$ 2
Coal Contract Total Contracts
Derivative
Fair value		0		0
Closed derivative contracts
Derivative
Fair value		$ (10)		$ (10)		$ (5)
[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 an66

Risk Management Activities and Derivative Transactions Offsetting of Derivative Assets and Liabilities (Details) - USD ($) $ in Millions		Jun. 30, 2015		Sep. 30, 2014
Offsetting Assets [Line Items]
Securities Posted by Counterparty on TVA's behalf		$ 9
Gross Amounts of Recognized Assets		116		$ 115
Gross Amounts Offset in the Balance Sheet	[1]	(55)		(115)
Net Amounts of Assets Presented in the Balance Sheet	[2]	64		1
Total derivatives not subject to master netting or similar arrangement	[2]	3		1
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement		119		116
Offsetting Liabilities [Line Items]
Gross amounts of recognized liabilities		1,622		1,517
Gross Amounts Offset in the Balance Sheet	[1]	(146)		(120)
Net Amounts of Liabilities Presented in the Balance Sheet	[2]	1,604		1,494
Total derivatives not subject to master netting or similar arrangement	[2]	128		97
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement		1,750		1,614
Cash Collateral in Excess of Collateral Requirements		0		19
Letter of Credit
Offsetting Liabilities [Line Items]
Amount of letters of credit outstanding		1,100		1,000
Currency Swap [Member]
Offsetting Assets [Line Items]
Gross Amounts of Recognized Assets		61	[3]	64
Gross Amounts Offset in the Balance Sheet	[1]	0	[3]	(64)
Net Amounts of Assets Presented in the Balance Sheet	[2]	61	[3]	0
Offsetting Liabilities [Line Items]
Gross amounts of recognized liabilities	[4]	23		15
Gross Amounts Offset in the Balance Sheet	[1],[4]	0		0
Net Amounts of Liabilities Presented in the Balance Sheet	[2],[4]	23		15
Interest Rate Contract [Member]
Offsetting Liabilities [Line Items]
Gross amounts of recognized liabilities	[4]	1,419		1,348
Gross Amounts Offset in the Balance Sheet	[1],[4]	0		0
Net Amounts of Liabilities Presented in the Balance Sheet	[2],[4]	1,419		1,348
Commodity derivatives under FTP
Offsetting Assets [Line Items]
Gross Amounts of Recognized Assets		55		51
Gross Amounts Offset in the Balance Sheet	[1]	(55)		(51)
Net Amounts of Assets Presented in the Balance Sheet	[2]	0		0
Offsetting Liabilities [Line Items]
Gross amounts of recognized liabilities		180		154
Gross Amounts Offset in the Balance Sheet	[1]	(146)		(120)
Net Amounts of Liabilities Presented in the Balance Sheet	[2]	34		34
Total derivatives subject to master netting or similar arrangement [Member]
Offsetting Assets [Line Items]
Net Amounts of Assets Presented in the Balance Sheet	[2]	61		0
Offsetting Liabilities [Line Items]
Net Amounts of Liabilities Presented in the Balance Sheet	[2]	$ 1,476		$ 1,397
[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 Consolidated Balance Sheets.
[3]	At June 30, 2015, securities of approximately $9 million were 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 and $1.0 billion were posted as collateral at June 30, 2015 and September 30, 2014, respectively, 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. At June 30, 2015, TVA held no cash collateral in excess of collateral requirements and at September 30, 2014, TVA held $19 million of cash collateral in excess of collateral requirements that was classified in Restricted cash and investments with a corresponding obligation recorded in Accounts payable and accrued liabilities in the same amount.

Risk Management Activities an67

Risk Management Activities and Derivative Transactions Collateral (Details) - Jun. 30, 2015 - Collateral - USD ($) $ in Millions	Total
Derivative
Derivative, net liability position, aggregate fair value	$ 1,400
Collateral obligations	1,000
Collateral already posted	1,100
Likely cash collateral obligation increase	$ 22

Risk Management Activities an68

Risk Management Activities and Derivative Transactions Counterparty Credit Risk (Details)	Jun. 30, 2015merchantsMegawattsCustomers	Apr. 14, 2015Megawatts	Sep. 30, 2014Customers
Derivative
Number of active future commission merchants | merchants	2
Megawatts of Power Purchase Agreement		700
Credit of Customers
Derivative
Number of customers that represent the concentration of accounts receivable percent outstanding | Customers	3		3
Percent of total outstanding accounts receivables	26.00%		27.00%
Megawatts of Power Purchase Agreement
Derivative
Megawatts of Power Purchase Agreement	440

Fair Value Measurements Investm

Fair Value Measurements Investments Gains (Losses) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Investment Gains (Losses)
Securities classified as trading and measured at fair value	$ 2,100		$ 2,100
NDT unfunded commitments related to private partnerships	92		92
SERP
Investment Gains (Losses)
Unrealized gains (losses) on investments	0	$ 1	0	$ 2
LTDCP [Member]
Investment Gains (Losses)
Unrealized gains (losses) on investments	0	0	(1)	0
NDT
Investment Gains (Losses)
Unrealized gains (losses) on investments	(19)	36	15	72
ART
Investment Gains (Losses)
Unrealized gains (losses) on investments	(3)	$ 9	12	$ 27
Maximum
Investment Gains (Losses)
Equity investments not required to be measured at fair value	$ 1		$ 1

Fair Value Measurements Nonperf

Fair Value Measurements Nonperformance Risk (Details) $ in Millions	Jun. 30, 2015USD ($)
Nonperformance Risk
Derivative credit valuation adjustment, assets	$ 4
Derivative credit valuation adjustment, liabilities	$ 1

Fair Value Measurements Fair Va

Fair Value Measurements Fair Value Measurements (Details) - USD ($) $ in Millions		Jun. 30, 2015		Sep. 30, 2014
Investments
Equity securities		$ 181		$ 162
Debt Instruments [Abstract]
U.S. government corporations and agencies		66		85
Corporate debt securities		336		290
Residential mortgage-backed securities		16		14
Commercial mortgage-backed securities		5		7
Collateralized debt obligations		29		29
Private partnerships		238		214
Commingled funds
Equity security commingled funds		986	[1]	943	[2]
Debt security commingled funds		222	[1]	237	[2]
Total investments		2,079		1,981
Currency swap(s)	[3]	61		0
Commodity contract derivatives		3		1
Commodity derivatives under FTP
Swap contracts	[3]	0		0
Total		2,143		1,982
Liabilities
Currency swap(s)	[3]	23		15
Derivative Liability, Fair Value, Gross Liability		1,622		1,517
Interest rate swaps		1,419		1,348
Commodity contract derivatives		128		97
Commodity derivatives under FTP
Swap contracts	[3]	34		34
Total		1,604		1,494
Fair Value, Inputs, Level 1
Investments
Equity securities		181		162
Debt Instruments [Abstract]
U.S. government corporations and agencies		59		46
Corporate debt securities		0		0
Residential mortgage-backed securities		0		0
Commercial mortgage-backed securities		0		0
Collateralized debt obligations		0		0
Private partnerships		0		0
Commingled funds
Equity security commingled funds		44	[1]	40	[2]
Debt security commingled funds		44	[1]	61	[2]
Total investments		328		309
Currency swap(s)	[3]	0		0
Commodity contract derivatives		0		0
Commodity derivatives under FTP
Swap contracts	[3]	0		0
Total		328		309
Liabilities
Currency swap(s)	[3]	0		0
Interest rate swaps		0		0
Commodity contract derivatives		0		0
Commodity derivatives under FTP
Swap contracts	[3]	0		0
Total		0		0
Fair Value, Inputs, Level 2
Investments
Equity securities		0		0
Debt Instruments [Abstract]
U.S. government corporations and agencies		7		39
Corporate debt securities		336		290
Residential mortgage-backed securities		16		14
Commercial mortgage-backed securities		5		7
Collateralized debt obligations		29		29
Private partnerships		0		0
Commingled funds
Equity security commingled funds		942	[1]	903	[2]
Debt security commingled funds		178	[1]	176	[2]
Total investments		1,513		1,458
Currency swap(s)		61	[3]	0	[4]
Commodity contract derivatives		0		0
Commodity derivatives under FTP
Swap contracts		0	[3]	0	[4]
Total		1,574		1,458
Liabilities
Currency swap(s)	[3]	23		15
Interest rate swaps		1,419		1,348
Commodity contract derivatives		0		0
Commodity derivatives under FTP
Swap contracts		34	[3]	34	[4]
Total		1,476		1,397
Fair Value, Inputs, Level 3
Investments
Equity securities		0		0
Debt Instruments [Abstract]
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
Private partnerships		238		214
Commingled funds
Equity security commingled funds		0	[1]	0	[2]
Debt security commingled funds		0	[1]	0	[2]
Total investments		238		214
Currency swap(s)	[3]	0		0
Commodity contract derivatives		3		1
Commodity derivatives under FTP
Swap contracts	[3]	0		0
Total		241		215
Liabilities
Currency swap(s)	[3]	0		0
Interest rate swaps		0		0
Commodity contract derivatives		128		97
Commodity derivatives under FTP
Swap contracts	[3]	0		0
Total		128		97
Currency Swap [Member]
Liabilities
Derivative Liability, Fair Value, Gross Liability	[5]	$ 23		$ 15
[1]	Commingled funds represent investment funds comprising multiple individual financial instruments and are classified in the table based on their existing investment portfolio as of the measurement date. Commingled funds primarily composed of one class of security are classified in that category.
[2]	Commingled funds represent investment funds comprising multiple individual financial instruments and are classified in the table based on their existing investment portfolio as of the measurement date. Commingled funds primarily composed of one class of security are classified in that category.
[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 any cash collateral received from or paid to the counterparty, to the extent such amount is not recorded in Accounts payable and accrued liabilities. See Note 15 — 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 any cash collateral received from or paid to the counterparty. See Note 15 — Offsetting of Derivative Assets and Liabilities.
[5]	Letters of credit of approximately $1.1 billion and $1.0 billion were posted as collateral at June 30, 2015 and September 30, 2014, respectively, 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. At June 30, 2015, TVA held no cash collateral in excess of collateral requirements and at September 30, 2014, TVA held $19 million of cash collateral in excess of collateral requirements that was classified in Restricted cash and investments with a corresponding obligation recorded in Accounts payable and accrued liabilities in the same amount.

Fair Value Measurements Fair 72

Fair Value Measurements Fair Value Measurements Using Significant Unobservable Inputs (Details) tons-per-year in Billions		3 Months Ended		9 Months Ended		12 Months Ended
		Jun. 30, 2015USD ($)tons-per-year	Jun. 30, 2014USD ($)	Jun. 30, 2015USD ($)tons-per-year	Jun. 30, 2014USD ($)	Sep. 30, 2014USD ($)Contractstons-per-year	Mar. 31, 2015USD ($)	Mar. 31, 2014USD ($)	Sep. 30, 2013USD ($)
ASSETS
Commodity contract derivatives		$ 3,000,000		$ 3,000,000		$ 1,000,000
Liabilities
Commodity contract derivatives		128,000,000		128,000,000		$ 97,000,000
Number of contracts | Contracts						2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amount of gain (loss) recognized in income		$ 0		$ 0
Maximum
ASSETS
Fair value inputs, counterparty credit risk	[1]					5.00%
Fair value measurements tons per year | tons-per-year		1		1		1.1
Price per ton		$ 103.41		$ 103.41		$ 67.07
Liabilities
Fair value measurements tons per year | tons-per-year		1		1		1.1
Price per ton		$ 103.41		$ 103.41		$ 67.07
Minimum
ASSETS
Fair value inputs, counterparty credit risk	[1]					2.00%
Fair value measurements tons per year | tons-per-year		0.8		0.8		1
Price per ton		$ 10.08		$ 10.08		$ 11.24
Liabilities
Fair value measurements tons per year | tons-per-year		0.8		0.8		1
Price per ton		$ 10.08		$ 10.08		$ 11.24
Fair Value, Inputs, Level 3
ASSETS
Commodity contract derivatives		3,000,000		3,000,000		1,000,000
Liabilities
Commodity contract derivatives		128,000,000		128,000,000		97,000,000
Private Partnerships
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Balance		238,000,000	$ 188,000,000	238,000,000	$ 188,000,000	214,000,000	$ 223,000,000	$ 180,000,000	$ 159,000,000
Purchases		11,000,000	7,000,000	21,000,000	23,000,000
Issuances		0	0	0	0
Sales		(5,000,000)	(6,000,000)	(12,000,000)	(7,000,000)
Settlements		0	0	0	0
Net unrealized gains (losses) deferred as regulatory assets and liabilities		9,000,000	7,000,000	15,000,000	13,000,000
Commodity Contract Derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Balance		(125,000,000)	(146,000,000)	(125,000,000)	(146,000,000)	$ (96,000,000)	$ (149,000,000)	$ (131,000,000)	$ (140,000,000)
Purchases		0	0	0	0
Issuances		0	0	0	0
Sales		0	0	0	0
Settlements		0	0	0	0
Net unrealized gains (losses) deferred as regulatory assets and liabilities		$ 24,000,000	$ (15,000,000)	$ (29,000,000)	$ (6,000,000)
[1]	Applies to two contracts.

Fair Value Measurements Estimat

Fair Value Measurements Estimated Values of Financial Instruments Not Recorded at Fair Value (Details) - USD ($) $ in Millions	Jun. 30, 2015	Sep. 30, 2014	Aug. 09, 2013
Estimated Values of Financial Intruments Not Recorded at Fair Value
EnergyRight receivables (including current portion)	$ 163	$ 166
Loans and other long-term receivables, net (including current portion)	99	81
EnergyRight® financing obligation (including current portion)	209	215
Unfunded Loan Commitments	20	18
Membership interest of variable interest entity subject to mandatory redemption (including current portion)	47	50	$ 40
Long-term outstanding power bonds (including current maturities), net	25,134	26,889
Long-term debt of variable interest entities (including current maturities)	1,392	1,425
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)	111	92
EnergyRight® financing obligation (including current portion)	186	190
Unfunded Loan Commitments	0	0
Membership interest of variable interest entity subject to mandatory redemption (including current portion)	38	39
Long-term outstanding power bonds (including current maturities), net	21,776	22,980
Long-term debt of variable interest entities (including current maturities)	$ 1,296	$ 1,311

Other Income (Expense), Net (De

Other Income (Expense), Net (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Other Income (Expense), Net
Interest income	$ 6	$ 6	$ 18	$ 17
External services	3	3	9	15
Gains (losses) on investments	0	2	3	4
Miscellaneous	(1)	(1)	(5)	1
Total other income (expense), net	$ 8	$ 10	$ 25	$ 37

Benefit Plans Components of Ben

Benefit Plans Components of Benefit Plans (Details) - 9 months ended Jun. 30, 2015	plans
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		9 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Pension Benefits
Defined Benefit Plan Disclosure
Service cost	$ 32	$ 33	$ 97	$ 98
Interest cost	135	139	405	418
Expected return on plan assets	(110)	(109)	(328)	(326)
Amortization of prior service cost	(5)	(5)	(16)	(16)
Recognized net actuarial loss	75	71	225	214
Total net periodic benefit cost as actuarially determined	127	129	383	388
Amount capitalized due to actions of regulator	(57)	0	(171)	0
Total net periodic benefit cost	70	129	212	388
Other Post-retirement Benefits
Defined Benefit Plan Disclosure
Service cost	4	5	12	14
Interest cost	7	8	22	24
Expected return on plan assets	0	0	0	0
Amortization of prior service cost	(2)	(2)	(5)	(5)
Recognized net actuarial loss	3	3	7	8
Total net periodic benefit cost as actuarially determined	12	14	36	41
Amount capitalized due to actions of regulator	0	0	0	0
Total net periodic benefit cost	$ 12	$ 14	$ 36	$ 41

Benefit Plans Contributions (De

Benefit Plans Contributions (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended		12 Months Ended
	Sep. 30, 2015	Jun. 30, 2015	Jun. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Other Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure
Defined Benefit Plan, Contributions by Employer		$ 138			$ 250
Other Post-retirement Benefits
Defined Benefit Plan Disclosure
Defined Benefit Plan, Contributions by Employer		31	$ 23
Supplemental Employee Retirement Plan
Defined Benefit Plan Disclosure
Defined Benefit Plan, Contributions by Employer		$ 7	$ 6
Scenario, Forecast [Member] | Other Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure
Defined Benefit Plan, Contributions by Employer	$ 137			$ 275

Contingencies and Legal Proce78

Contingencies and Legal Proceedings Contingencies (Details) - Jun. 30, 2015 $ in Thousands	USD ($)UnitsreactorsInsurance_layersProceduresSites
Loss Contingencies [Line Items]
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	102
Nuclear accident assessment limitation per year per unit	$ 19,000
Number of licensed nuclear units | Units	6
Maximum assessment per nuclear incident	$ 764,000
Maximum payment required per incident in any one year	114,000
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	$ 800,000
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	9,000
Nuclear
Loss Contingencies [Line Items]
Present value of estimated future decommissioning cost	2,100,000
Non-nuclear
Loss Contingencies [Line Items]
Present value of estimated future decommissioning cost	$ 1,700,000

Contingencies and Legal Proce79

Contingencies and Legal Proceedings Legal Proceedings (Details)

1 Months Ended

9 Months Ended

12 Months Ended

Jul. 31, 2013Legal_actions

May. 31, 2013

Jun. 30, 2012

Dec. 31, 2011Legal_actions

Apr. 30, 2011GroupsAgreements

Sep. 30, 2010

Mar. 31, 2010People

Nov. 30, 2009PeopleLegal_actions

Jun. 30, 2008Legal_actions

Oct. 31, 2007Legal_actions

Jun. 30, 2015USD ($)Legal_actions

Dec. 31, 2010Years

Apr. 30, 2015Legal_actions

Apr. 14, 2015Megawatts

Jun. 30, 2011USD ($)UnitsMegawatts

Jun. 30, 2010USD ($)

Legal Proceedings

Possible additional future costs for compliance with Clean Air Act requirements | $

$ 800,000,000

Megawatts | Megawatts

700

Term of payments for civil penalty

3 years

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

2

Number of units at John Sevier Fossil

4

General

Legal Proceedings

Legal loss contingency accrual | $

$ 145,000,000

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 | Megawatts

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

Kingston Ash Spill

Legal Proceedings

Number of lawsuits filed

78

Number of lawsuits dismissed

15

2

Loss Contingency, Claims Dismissed, Number

63

Number of active lawsuits

9

Payments for Legal Settlements | $

$ 28,000,000

Loss Contingency, Claims Settled, Number

7

Civil penalty order issued June 1, 2010 | $

$ 12,000,000

Amount of civil penalty order satisfied | $

$ 10,000,000

Credit against civil penalty order | $

2,000,000

Down payment on natural resource damages | $

750,000

Case Involving Tennessee Valley Authority Retirement System

Legal Proceedings

Number of participants that filed suit | People

8

Number of TVARS Board members | People

6

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

Number of days to file an ammended complaint

14 days

Case Involving the NRC Waste Confidence Decision on Spent Nuclear Fuel Storage

Legal Proceedings

Number of years that spent fuel can be stored after a plant's license is terminated

60 years

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

7

Number of contentions left

1

Administrative Proceedings Regarding Bellefonte Units 3 and 4

Legal Proceedings

Number of contentions left

2

Number of admitted contentions submitted by BREDL and SACE

4

Number of contentions submitted by BREDL and SACE

20

Number of contentions no longer admitted

2

Administrative Proceedings Regarding Watts Bar Nuclear Plant Unit 2

Legal Proceedings

Number of contentions dismissed

1

Number of contentions admitted for hearing

2

Number of SACE contentions

7

Number of other petitioners | People

4

Number of contentions remaining

1

Petitions Resulting from Japanese Nuclear Events

Legal Proceedings

Number of requests accepted by the NRC

5

Other Noncurrent Liabilities [Member] | General

Legal Proceedings

Legal loss contingency accrual | $

63,000,000

Accounts payable and accrued liabilities | General

Legal Proceedings

Legal loss contingency accrual | $

$ 82,000,000