Tennessee Valley Authority PARRS D 2028 (TVC) 10-Q 2 May 17 2017 Q2 Quarterly report Financial data

DEI Document

DEI Document shares in Millions, $ in Millions	6 Months Ended
	Mar. 31, 2017USD ($)shares
Document Information [Line Items]
Entity Registrant Name	Tennessee Valley Authority
Entity Central Index Key	1,376,986
Current Fiscal Year End Date	--09-30
Entity Filer Category	Non-accelerated Filer
Document Type	10-Q
Document Period End Date	Mar. 31, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	Q2
Amendment Flag	false
Entity Common Stock, Shares Outstanding | shares	0
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float | $	$ 0

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS (UNAUDITED) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2017	Mar. 31, 2016
Operating revenues
Revenue from sales of electricity	$ 2,508	$ 2,529	$ 5,016	$ 4,775
Other revenue	39	42	77	76
Total operating revenues	2,547	2,571	5,093	4,851
Operating expenses
Fuel	503	484	1,071	964
Purchased power	244	237	486	484
Operating and maintenance	699	669	1,440	1,409
Depreciation and amortization	438	465	875	926
Tax equivalents	129	127	258	251
Total operating expenses	2,013	1,982	4,130	4,034
Operating income	534	589	963	817
Other income (expense), net	15	8	27	20
Interest expense
Interest expense	338	337	677	672
Allowance for funds used during construction	0	(58)	0	(116)
Net interest expense	338	279	677	556
Net income (loss)	$ 211	$ 318	$ 313	$ 281

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (UNAUDITED) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2017	Mar. 31, 2016
Net income (loss)		$ 211	$ 318	$ 313	$ 281
Other comprehensive income (loss)
Net unrealized gain (loss) on cash flow hedges		25	(27)	17	(54)
Reclassification to earnings from cash flow hedges	[1]	(12)	22	26	46
Total other comprehensive income (loss)		13	(5)	43	(8)
Total comprehensive income (loss)		$ 224	$ 313	$ 356	$ 273
[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 $15 million of gains from AOCI to interest expense within the next twelve months to offset amounts anticipated to be recorded in interest expense related to net exchange gain on the debt.

CONSOLIDATED BALANCE SHEETS (UN

CONSOLIDATED BALANCE SHEETS (UNAUDITED) - USD ($) $ in Millions	Mar. 31, 2017	Sep. 30, 2016
Current assets
Cash and cash equivalents	$ 300	$ 300
Accounts receivable, net	1,310	1,747
Inventories, net	1,148	993
Regulatory assets	408	536
Other current assets	113	68
Total current assets	3,279	3,644
Property, plant, and equipment
Completed plant	57,019	51,564
Less accumulated depreciation	(27,930)	(27,592)
Net completed plant	29,089	23,972
Construction in progress	3,583	8,458
Nuclear fuel	1,429	1,450
Capital leases	161	163
Total property, plant, and equipment, net	34,262	34,043
Investment funds	2,388	2,257
Regulatory and other long-term assets
Regulatory assets	9,495	10,164
Other long-term assets	380	386
Total regulatory and other long-term assets	9,875	10,550
Total assets	49,804	50,494
Current liabilities
Accounts payable and accrued liabilities	1,893	2,163
Accrued interest	374	363
Current portion of leaseback obligations	60	58
Current portion of energy prepayment obligations	100	100
Regulatory liabilities	183	154
Short-term debt, net	815	1,407
Current maturities of power bonds	1,681	1,555
Current maturities of long-term debt of variable interest entities	35	35
Current maturities of notes payable	28	27
Total current liabilities	5,169	5,862
Other liabilities
Post-retirement and post-employment benefit obligations	6,770	6,929
Asset retirement obligations	3,915	3,840
Other long-term liabilities	2,318	2,776
Leaseback obligations	371	409
Energy prepayment obligations	60	110
Total other liabilities	13,434	14,064
Long-term debt, net
Long-term power bonds, net	21,225	20,901
Long-term debt of variable interest entities, net	1,182	1,199
Long-term notes payable	21	48
Total long-term debt, net	22,428	22,148
Total liabilities	41,031	42,074
Proprietary capital
Power program appropriation investment	258	258
Power program retained earnings	7,908	7,594
Total power program proprietary capital	8,166	7,852
Nonpower programs appropriation investment, net	576	580
Accumulated other comprehensive income (loss)	31	(12)
Total proprietary capital	8,773	8,420
Total liabilities and proprietary capital	$ 49,804	$ 50,494

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED) - USD ($) $ in Millions	6 Months Ended
	Mar. 31, 2017		Mar. 31, 2016
Cash flows from operating activities
Net income (loss)	$ 313		$ 281
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)	898		949
Amortization of nuclear fuel cost	172		126
Noncash retirement benefit expense	168		163
Prepayment credits applied to revenue	(50)		(50)
Fuel cost adjustment deferral	106		(16)
Fuel cost tax equivalents	2		(15)
Changes in current assets and liabilities
Accounts receivable, net	440		385
Inventories and other current assets, net	(83)		(62)
Accounts payable and accrued liabilities	(216)		(203)
Accrued interest	11		14
Regulatory assets costs	(14)		(17)
Pension contributions	(155)		(143)
Other, net	(76)		(82)
Net cash provided by operating activities	1,516		1,330
Cash flows from investing activities
Construction expenditures	(1,119)		(1,477)
Nuclear fuel expenditures	(195)		(138)
Loans and other receivables
Advances	(5)		(4)
Repayments	2		3
Other, net	15		3
Net cash used in investing activities	(1,302)		(1,613)
Long-term debt
Issues of power bonds	999		0
Redemptions and repurchases of power bonds	(528)	[1]	(6)
Redemptions of variable interest entities	(17)		(16)
Redemptions of notes payable	(26)		0
Short-term debt issues (redemptions), net	(595)		372
Payments on leases and leasebacks	(38)		(59)
Financing costs, net	(4)		0
Payments to U.S. Treasury	(3)		(3)
Other, net	(2)		(4)
Net cash provided by (used in) financing activities	(214)		284
Net change in cash and cash equivalents	0		1
Cash and cash equivalents at beginning of period	300		300
Cash and cash equivalents at end of period	300		301
Significant non-cash transactions
Accrued capital and nuclear fuel expenditures	395		410
Capital lease obligations incurred	$ 3		$ 9
[1]	All redemptions were at 100 percent of par.

CONSOLIDATED STATEMENTS OF CHAN

CONSOLIDATED STATEMENTS OF CHANGES IN PROPRIETARY CAPITAL (UNAUDITED) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016	Sep. 30, 2016	Dec. 31, 2015	Sep. 30, 2015
Power Program Appropriation Investment	$ 258		$ 258			$ 258
Power Program Retained Earnings	7,908		7,908			7,594
Nonpower Programs Appropriation Investment, Net	576		576			580
Accumulated Other Comprehensive Income (Loss) from Net Gains (Losses) on Cash Flow Hedges	31		31			(12)
Total Proprietary Capital	8,773	$ 7,473	8,773	$ 7,473	$ 8,551	8,420	$ 7,161	$ 7,203
Net income (loss)	211	318	313	281
Total other comprehensive income (loss)	13	(5)	43	(8)
Return on power program appropriation investment	(2)	(1)	(3)	(3)
Power Program Appropriation Investment
Power Program Appropriation Investment	258	258	258	258	258	258	258	258
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
Power Program Retained Earnings
Power Program Retained Earnings	7,908	6,640	7,908	6,640	7,697	7,594	6,321	6,357
Net income (loss)	213	320	317	286
Total other comprehensive income (loss)	0	0	0	0
Return on power program appropriation investment	(2)	(1)	(3)	(3)
Nonpower Programs Appropriation Investment, Net
Nonpower Programs Appropriation Investment, Net	576	585	576	585	578	580	587	590
Net income (loss)	(2)	(2)	(4)	(5)
Total other comprehensive income (loss)	0	0	0	0
Return on power program appropriation investment	0	0	0	0
Accumulated Other Comprehensive Income (Loss) from Net Gains (Losses) on Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss) from Net Gains (Losses) on Cash Flow Hedges	31	(10)	31	(10)	$ 18	$ (12)	$ (5)	$ (2)
Net income (loss)	0	0	0	0
Total other comprehensive income (loss)	13	(5)	43	(8)
Return on power program appropriation investment	$ 0	$ 0	$ 0	$ 0

Summary of Significant Accounti

Summary of Significant Accounting Policies	6 Months Ended
	Mar. 31, 2017
Accounting Policies [Abstract]
Nature of Operations and Summary of Significant Accounting Policies	Nature of Operations and Summary of Significant Accounting Policies General The Tennessee Valley Authority ("TVA") is a corporate agency and instrumentality of the United States ("U.S.") that was created in 1933 by legislation enacted by the 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 over 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 and public lands to provide recreational opportunities, adequate water supply, improved water quality, cultural and 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. Fiscal Year TVA's fiscal year ends September 30. Years ( 2017 , 2016 , 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. All regulatory asset write offs would be required to be recognized in earnings in the period in which future recovery ceases to be probable. Basis of Presentation TVA prepares its consolidated interim financial statements in conformity with GAAP for consolidated interim financial information. Accordingly, TVA's consolidated interim financial statements do not include all of the information and notes required by GAAP for annual financial statements. As such, they should be read in conjunction with the audited financial statements for the year ended September 30, 2016 , and the notes thereto, which are contained in TVA's Annual Report on Form 10-K for the year ended September 30, 2016 (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 consolidated interim financial statements. The accompanying consolidated interim financial statements, which have been prepared in accordance with GAAP, include the accounts of TVA, two wholly-owned direct subsidiaries, and three variable interest entities ("VIE") of which TVA is the primary beneficiary. See Note 7 . Intercompany balances and transactions have been eliminated in consolidation. Use of Estimates The preparation of financial statements requires TVA to estimate the effects of various matters that are inherently uncertain as of the date of the consolidated financial statements. Although the consolidated financial statements are prepared in conformity with GAAP, TVA is required to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities, and the amounts of revenues and expenses reported during the reporting period. Each of these estimates varies in regard to the level of judgment involved and its potential impact on TVA's financial results. Estimates are considered critical either when a different estimate could have reasonably been used, or where changes in the estimate are reasonably likely to occur from period to period, and such use or change would materially impact TVA's financial condition, results of operations, or cash flows. Reclassifications Certain historical amounts have been reclassified in the Consolidated Statement of Cash Flows for the six months ended March 31, 2016. Amounts previously presented in Cash flows from operating activities as Insurance recoveries of $7 million for the six months ended March 31, 2016, are currently reported in 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. It also reflects TVA's corporate credit department's assessment of the financial condition of customers and the credit quality of the receivables. The allowance for uncollectible accounts was $ 1 million at both March 31, 2017 , and September 30, 2016 , for accounts receivable. Additionally, loans receivable of $ 161 million and $ 141 million at March 31, 2017 , and September 30, 2016 , respectively, are included in Accounts receivable, net and Other long-term assets, for the current and long-term portions, respectively, and reported net of allowances for uncollectible accounts of $ 8 million at both March 31, 2017 , and September 30, 2016 . Pre-Commercial Plant Operations As part of the process of completing the construction of a generating unit, the electricity produced is used to serve the demands of the electric system. TVA estimates revenue from such pre-commercial generation based on the guidance provided by Federal Energy Regulatory Commission ("FERC") regulations. Watts Bar Nuclear Plant ("Watts Bar") Unit 2 commenced pre-commercial plant operations on June 3, 2016, and commercial operations began on October 19, 2016. TVA has also constructed a natural gas-fired generation facility at its Paradise Fossil Plant site which commenced pre-commercial plant operations on October 10, 2016, and commercial operations on April 7, 2017. Estimated revenue of $ 6 million and $ 20 million , related to these projects, was capitalized to offset project costs and is included in Revenue from sales of electricity as a contra-revenue amount on the consolidated statement of operations for the three and six months ended March 31, 2017 , respectively. TVA also capitalized related fuel costs for these two construction projects of approximately $ 8 million and $ 13 million during the three and six months ended March 31, 2017 , respectively. Depreciation Depreciation expense was $336 million and $369 million for the three months ended March 31, 2017 and 2016 , respectively, and $ 672 million and $ 733 million for the six months ended March 31, 2017 and 2016 , respectively. Depreciation rates are determined based on an external depreciation study. TVA concluded and implemented the results of a new study effective October 1, 2016. Implementation of the new depreciation rates resulted in an estimated decrease of approximately $ 56 million and $ 112 million in depreciation and amortization expense during the three and six months ended March 31, 2017 , respectively, as compared to the same periods of the prior year. This estimate represents the impact of implementing the new depreciation rates only and does not include any potential impact of other possible changes, including additions to or retirements of net completed plant that occurred during the same period. The decrease in depreciation expense as a result of the new depreciation rates is primarily attributable to the use of TVA's current generation plans, which resulted in changes in retirement date assumptions for coal-fired plants, and changes in the estimated service lives for transmission assets. Allowance for Funds Used During Construction TVA may capitalize interest on eligible projects as allowance for funds used during construction ("AFUDC") , based on the average interest rate of TVA’s outstanding debt. The allowance is applicable to construction in progress related to eligible projects with (1) an expected total project cost of $ 1.0 billion or more, and (2) an estimated construction period of at least three years in duration. TVA capitalized $ 58 million and $ 116 million of AFUDC for the three and six months ended March 31, 2016 , respectively, related to the Watts Bar Unit 2 project which went into service in October 2016. No AFUDC was recorded for comparable periods in the current year. 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 $ 160 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 March 31, 2017 , TVA had paid out approximately $ 151 million for this program, and the obligation recorded was $ 9 million .

Impact of New Accounting Standa

Impact of New Accounting Standards and Interpretations	6 Months Ended
	Mar. 31, 2017
Accounting Changes and Error Corrections [Abstract]
Impact of New Accounting Standards and Interpretations	Impact of New Accounting Standards and Interpretations The following are accounting standard updates issued by the Financial Accounting Standards Board ("FASB") that TVA adopted during 2017. Consolidation Description This guidance amends the consolidation analysis for VIEs as well as voting interest entities. The standard reduces the number of consolidation models through the elimination of the indefinite deferral for certain entities that was previously allowed and places more emphasis on risk of loss when determining a controlling financial interest. This guidance allows for either a full retrospective or a modified retrospective application. Effective Date for TVA October 1, 2016 Effect on the Financial Statements or Other Significant Matters The adoption of the standard did not materially impact TVA's financial condition, results of operations, or cash flows. The following accounting standards have been issued, but as of March 31, 2017 , were not effective and had not been adopted by TVA. Defined Benefit Costs Description This guidance changes how information about defined benefit costs for pension plans and other post-retirement benefit plans is presented in employer financial statements. The guidance requires employers that present a measure of operating income in their statement of income to include only the service cost component of net periodic pension cost and net periodic postretirement benefit cost in operating expenses (together with other employee compensation costs). The other components of net benefit cost, including amortization of prior service cost/credit, and settlement and curtailment effects, are to be included in nonoperating expenses. Additionally, the guidance stipulates that only the service cost component of net benefit cost is eligible for capitalization in assets. Effective Date for TVA The new standard is effective for TVA’s interim and annual reporting periods beginning October 1, 2018. While early adoption is permitted, TVA does not currently plan to adopt the standard early. Effect on the Financial Statements or Other Significant Matters TVA is currently evaluating the potential impact of these changes on its consolidated financial statements and related disclosures. Revenue Recognition Description In 2014, the FASB issued new guidance related to revenue from contracts with customers. The guidance, including subsequent amendments, replaces the existing accounting standard and industry specific guidance for revenue recognition with a five-step model for recognizing and measuring revenue from contracts with customers. The underlying principle of the guidance is to recognize revenue to depict the transfer of goods or services to customers at the amount expected to be collected. The objective of the new standard is to provide a single, comprehensive revenue recognition model for all contracts with customers to improve comparability within industries and across industries. The new standard also requires enhanced disclosures regarding the nature, amount, timing, and uncertainty of revenue and the related cash flows arising from contracts with customers. At adoption, companies must also select a transition method to be applied either retrospectively to each prior reporting period presented or retrospectively with a cumulative effect adjustment to retained earnings at the date of initial adoption. Effective Date for TVA The new standard is effective for TVA’s interim and annual reporting periods beginning October 1, 2018. While early adoption is permitted, TVA does not currently plan to adopt the standard early. Effect on the Financial Statements or Other Significant Matters While TVA expects most of its revenue to be included in the scope of the new guidance, it has not completed its evaluation of all such arrangements. TVA’s current efforts in evaluating the impact of the standard are focused on scoping of revenue streams and evaluating contracts with local power companies, which represent the majority of TVA's revenues. TVA is also conducting ongoing evaluations of how the new guidance impacts other transactions, including sales to directly served industrial customers, sales to federal agencies, purchase power agreements, contributions in aid of construction, fuel cost adjustments, and other revenue streams. In addition, the power and utilities industry is currently addressing certain industry-specific issues which have not yet been finalized. As the ultimate impact of the new standard has not yet been determined, TVA has not yet elected its transition method. Inventory Valuation Description This guidance changes the model used for the subsequent measurement of inventory from the previous lower of cost or market model to the lower of cost or net realizable value. The guidance applies only to inventory valued using methods other than last-in, first out or the retail inventory method (for example, first-in, first-out or average cost). This amendment is intended to simplify the subsequent measurement of inventory. When the standard becomes effective, it includes interim periods within the fiscal year that begins on that date, and is required to be applied prospectively. Effective Date for TVA The new standard is effective for TVA’s interim and annual reporting periods beginning October 1, 2017. While early adoption is permitted, TVA does not currently plan to adopt the standard early. Effect on the Financial Statements or Other Significant Matters TVA does not expect the adoption of this standard to have a material impact on TVA's financial condition, results of operations, or cash flows. Lease Accounting Description This guidance changes the provisions of recognition in both the lessee and lessor accounting models. The standard requires entities that lease assets — referred to as "lessees" — to recognize on the balance sheet the assets and liabilities for the rights and obligations created by leases with terms of more than 12 months. The recognition, measurement, and presentation of expenses and cash flows arising from a lease by a lessee primarily will depend on its classification as a finance (similar to current capital leases) or operating lease. However, unlike current lease accounting rules — which require only capital leases to be recognized on the balance sheet — the new standard will require both types of leases to be recognized on the balance sheet. Operating leases will result in straight-line expense, while finance leases will result in recognition of interest on the lease liability separate from amortization expense. The accounting for the owner of the assets leased by the lessee — also known as lessor accounting — will remain largely unchanged from current lease accounting rules. When the standard becomes effective, it will include interim periods within that fiscal year, and will be required to be applied using a modified retrospective transition. Effective Date for TVA The new standard is effective for TVA’s interim and annual reporting periods beginning October 1, 2019. While early adoption is permitted, TVA does not currently plan to adopt the standard early. Effect on the Financial Statements or Other Significant Matters TVA is currently evaluating the potential impact of these changes on its consolidated financial statements and related disclosures. Financial Instruments Description This guidance applies to the recognition and measurement of financial assets and liabilities. The standard requires all equity investments to be measured at fair value with changes in the fair value recognized through net income (other than those accounted for under the equity method of accounting or those that result in consolidation of the investee). The standard also amends presentation requirements related to certain changes in the fair value of a liability and eliminates certain disclosure requirements of significant assumptions for financial instruments measured at amortized cost on the balance sheet. Public entities must apply the amendments by means of a cumulative-effect adjustment to the balance sheet as of the beginning of the fiscal year of adoption. Effective Date for TVA The new standard is effective for TVA’s interim and annual reporting periods beginning October 1, 2018. Early adoption is not permitted unless specific early adoption guidance is applied. TVA does not currently plan to adopt the standard early. Effect on the Financial Statements or Other Significant Matters TVA currently measures all of its equity investments (other than those that result in the consolidation of the investee) at fair value, with changes in the fair value recognized through net income. If TVA’s Board has authorized the use of regulatory accounting, the changes in fair value are deferred as regulatory assets or liabilities. TVA currently discloses significant assumptions around its estimates of fair value for financial instruments carried at amortized cost on its consolidated balance sheet. TVA is currently evaluating the potential impact of the changes in this new guidance on its consolidated financial statements and related disclosures. Derivatives and Hedging Description This guidance clarifies the requirements for assessing whether contingent call or put options that can accelerate the payment of principal on debt instruments are clearly and closely related to their debt hosts. An entity performing the assessment under the amendments in this update is required to assess the embedded call or put options solely in accordance with a four-step decision sequence. When the standard becomes effective, it will include interim periods within that fiscal year, and will be required to be applied using a modified retrospective transition. Effective Date for TVA The new standard is effective for TVA’s interim and annual reporting periods beginning October 1, 2017. While early adoption is permitted, TVA does not currently plan to adopt the standard early. Effect on the Financial Statements or Other Significant Matters TVA has two issues of Putable Automatic Rate Reset Securities (“PARRS”) outstanding. After a fixed-rate period of five years, the coupon rate on the PAARS may automatically be reset downward under certain market conditions on an annual basis. The coupon rate reset on the PARRS is based on a calculation. If the coupon rate is going to be reset, holders may request, for a limited period of time, redemption of the Bonds at par value, with repayment of principal on the reset date. This put option is otherwise not available. For both series of PARRS, the coupon rate will reset downward on the reset date if the rate calculated is below the then-current coupon rate on the Bond. TVA plans to assess whether these contingent put options, that can accelerate the payment of principal on the PARRS, continue to be clearly and closely related to their debt hosts under the new guidance. TVA plans to assess the put options in accordance with the four-step decision sequence clarified in the guidance. While a preliminary assessment indicates that TVA does not believe the new guidance will impact its current assessment, TVA will continue to evaluate the potential impact of the new guidance on its consolidated balance sheet.

Accounts Receivable, Net

Accounts Receivable, Net	6 Months Ended
	Mar. 31, 2017
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 March 31, 2017 At September 30, 2016 Power receivables $ 1,233 $ 1,637 Other receivables 78 111 Allowance for uncollectible accounts (1 ) (1 ) Accounts receivable, net $ 1,310 $ 1,747

Inventories, Net

Inventories, Net	6 Months Ended
	Mar. 31, 2017
Inventory, Net [Abstract]
Inventories, Net	Inventories, Net The table below summarizes the types and amounts of TVA’s inventories: Inventories, Net At March 31, 2017 At September 30, 2016 Materials and supplies inventory $ 745 $ 673 Fuel inventory 418 345 Emission allowance inventory, net 16 14 Allowance for inventory obsolescence (31 ) (39 ) Inventories, net $ 1,148 $ 993

Other Long-Term Assets

Other Long-Term Assets	6 Months Ended
	Mar. 31, 2017
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 March 31, 2017 At September 30, 2016 Loans and other long-term receivables, net $ 157 $ 136 EnergyRight ® receivables 108 112 Prepaid capacity payments 38 42 Commodity contract derivative assets — 3 Other 77 93 Other long-term assets $ 380 $ 386 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 March 31, 2017 , and September 30, 2016 , the carrying amount of the loans receivable, net of discount, reported in Accounts receivable, net was approximately $ 27 million and $ 29 million , respectively. See Note 8 for information regarding the associated financing obligation.

Regulatory Assets and Liabiliti

Regulatory Assets and Liabilities	6 Months Ended
	Mar. 31, 2017
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 March 31, 2017 At September 30, 2016 Current regulatory assets Deferred nuclear generating units $ 237 $ 237 Unrealized losses on commodity derivatives 109 122 Fuel cost adjustment receivable — 98 Environmental agreements 17 34 Environmental cleanup costs - Kingston ash spill 43 42 Other current regulatory assets 2 3 Total current regulatory assets 408 536 Non-current regulatory assets Deferred pension costs and other post-retirement benefits costs 5,270 5,385 Unrealized losses on interest rate derivatives 1,088 1,547 Nuclear decommissioning costs 882 938 Deferred nuclear generating units 871 850 Non-nuclear decommissioning costs 822 819 Environmental cleanup costs - Kingston ash spill 283 299 Unrealized losses on commodity derivatives 33 56 Environmental agreements 14 18 Other non-current regulatory assets 232 252 Total non-current regulatory assets 9,495 10,164 Total regulatory assets $ 9,903 $ 10,700 Current regulatory liabilities Fuel cost adjustment tax equivalents $ 150 $ 148 Fuel cost adjustment payable 8 — Unrealized gains on commodity derivatives 25 6 Total current regulatory liabilities 183 154 Non-current regulatory liabilities Unrealized gains on commodity derivatives — 3 Total regulatory liabilities $ 183 $ 157 Deferred Nuclear Generation Units . On November 14, 2016, following a public auction, TVA entered into a contract to sell substantially all of the Bellefonte Nuclear Plant ("Bellefonte") site for $ 111 million. The net book value of the Bellefonte assets to be sold and the related asset retirement costs are collectively $ 121 million and are included in Regulatory asset-Deferred nuclear generating units on TVA’s Consolidated Balance Sheet at March 31, 2017 , as approved by the TVA Board. TVA received $ 22 million on November 14, 2016, which is recorded as a long-term liability on TVA’s Consolidated Balance Sheet at March 31, 2017 , with the remaining $ 89 million due at closing. The buyer has up to two years to close on the property. The closing is subject to, among other conditions, a determination by TVA's Chief Executive Officer that potential environmental impacts have been appropriately addressed or are acceptable. Proceeds received from the sale will be recorded as a reduction to the regulatory asset upon closing and will reduce amounts collected in future rates. Any subsequent losses resulting from the disposition or impairment of Bellefonte will be recovered in future rates until fully recovered based upon the TVA Board-approved recovery of the Regulatory asset-Deferred nuclear generating units in future rates at an amount of $ 237 million per year until fully recovered.

Variable Interest Entities

Variable Interest Entities	6 Months Ended
	Mar. 31, 2017
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Variable Interest Entities	Variable Interest Entities A VIE is an entity that either (i) has insufficient equity to permit the entity to finance its activities without additional subordinated financial support or (ii) has equity investors who lack the characteristics of owning a controlling financial interest. When TVA determines that it has a variable interest in a variable interest entity, a qualitative evaluation is performed to assess which interest holders have the power to direct the activities that most significantly impact the economic performance of the entity and have the obligation to absorb losses or receive benefits that could be significant to the entity. The evaluation considers the purpose and design of the business, the risks that the business was designed to create and pass along to other entities, the activities of the business that can be directed and which party can direct them, and the expected relative impact of those activities on the economic performance of the business through its life. TVA has the power to direct the activities of an entity when it has the ability to make key operating and financing decisions, including, but not limited to, capital investment and the issuance of debt. Based on the evaluation of these criteria, TVA has determined it is the primary beneficiary of three entities and as such is required to account for the VIEs on a consolidated basis. John Sevier VIEs In 2012, TVA entered into a $ 1.0 billion construction management agreement and lease financing arrangement with John Sevier Combined Cycle Generation LLC ("JSCCG") for the completion and lease by TVA of the John Sevier Combined Cycle Facility ("John Sevier CCF") . JSCCG is a special single-purpose limited liability company formed in January 2012 to finance the John Sevier CCF through a $ 900 million secured note issuance (the “JSCCG notes”) and the issuance of $ 100 million of membership interests subject to mandatory redemption. The membership interests were purchased by John Sevier Holdco LLC ("Holdco") . Holdco is a special single-purpose entity, also formed in January 2012, established to acquire and hold the membership interests in JSCCG. A non-controlling interest in Holdco is held by a third party through nominal membership interests, to which none of the income, expenses, and cash flows is allocated. The membership interests held by Holdco in JSCCG were purchased with proceeds from the issuance of $ 100 million of secured notes (the “Holdco notes") and are subject to mandatory redemption pursuant to scheduled amortizing, semi-annual payments due each January 15 and July 15, with a final payment due in January 2042. The payment dates for the mandatorily redeemable membership interests are the same as those of the Holdco notes. The sale of the JSCCG notes, the membership interests in JSCCG, and the Holdco notes closed in January 2012. The JSCCG notes are secured by TVA’s lease payments, and the Holdco notes are secured by Holdco's investment in, and amounts receivable from, JSCCG. TVA’s lease payments to JSCCG are equal to and payable on the same dates as JSCCG’s and Holdco’s semi-annual debt service payments. In addition to the lease payments, TVA pays administrative and miscellaneous expenses incurred by JSCCG and Holdco. Certain agreements related to this transaction contain default and acceleration provisions. Southaven VIE In 2013, TVA entered into a lease financing arrangement with Southaven Combined Cycle Generation LLC ("SCCG") for the lease by TVA of the Southaven Combined Cycle Facility ("Southaven CCF") . SCCG is a special single-purpose limited liability company formed in June 2013 to finance the Southaven CCF through a $ 360 million secured notes issuance (the “SCCG notes”) and the issuance of $ 40 million of membership interests subject to mandatory redemption. The membership interests were purchased by Southaven Holdco LLC ("SHLLC") . SHLLC is a special single-purpose entity, also formed in June 2013, established to acquire and hold the membership interests of SCCG. A non-controlling interest in SHLLC is held by a third party through nominal membership interests, to which none of the income, expenses, and cash flows of SHLLC are allocated. The membership interests held by SHLLC were purchased with proceeds from the issuance of $ 40 million of secured notes (the "SHLLC notes"), and are subject to mandatory redemption pursuant to a schedule of amortizing, semi-annual payments due each February 15 and August 15, with a final payment due on August 15, 2033. The payment dates for the mandatorily redeemable membership interests are the same as those of the SHLLC notes and the payment amounts are sufficient to provide returns on, as well as returns of, capital until the investment has been repaid to SHLLC in full. The rate of return on investment to SHLLC is 7.0 percent , which is reflected as interest expense in the consolidated statements of operations. SHLLC is required to pay a pre-determined portion of the return on investment to Seven States Southaven, LLC ("SSSL") on each lease payment date as agreed in SHLLC's formation documents (the "Seven States Return"). The current and long-term portions of the Membership interests of VIE subject to mandatory redemption are included in Accounts payable and accrued liabilities and Other long-term liabilities, respectively. The payment dates for the mandatorily redeemable membership interests are the same as those of the SHLLC notes. The SCCG notes are secured by TVA’s lease payments, and the SHLLC notes are secured by SHLLC’s investment in, and amounts receivable from, SCCG. TVA’s lease payments to SCCG are payable on the same dates as SCCG’s and SHLLC’s semi-annual debt service payments and are equal to the sum of (i) the amount of SCCG’s semi-annual debt service payments, (ii) the amount of SHLLC’s semi-annual debt service payments, and (iii) the amount of the Seven States Return. In addition to the lease payments, TVA pays administrative and miscellaneous expenses incurred by SCCG and SHLLC. Certain agreements related to this transaction contain default and acceleration provisions. In the event that TVA were to choose to exercise an early buy out feature of the Southaven Facility Lease, in part or in whole, TVA must pay to SCCG amounts sufficient for SCCG to repay or partially repay on a pro rata basis the membership interests held by SHLLC, including any outstanding investment amount plus accrued but unpaid return. TVA also has the right, at any time and without any early redemption of the other portions of the Southaven Facility Lease payments due to SCCG, to fully repay SHLLC's investment, upon which repayment SHLLC will transfer the membership interests to a designee of TVA. Impact on Consolidated Financial Statements The financial statement items attributable to carrying amounts and classifications of JSCCG, Holdco, and SCCG as of March 31, 2017 , and September 30, 2016 , as reflected in the consolidated balance sheets are as follows: Summary of Impact of VIEs on Consolidated Balance Sheets At March 31, 2017 At September 30, 2016 Current liabilities Accrued interest $ 11 $ 11 Accounts payable and accrued liabilities 2 2 Current maturities of long-term debt of variable interest entities 35 35 Total current liabilities 48 48 Other liabilities Other long-term liabilities 31 33 Long-term debt, net Long-term debt of variable interest entities, net 1,182 1,199 Total liabilities $ 1,261 $ 1,280 Interest expense of $15 million for the three months ended March 31, 2017 and 2016 and $30 million and $31 million for the six months ended March 31, 2017 and 2016 , respectively, is included in the Consolidated Statements of Operations related to debt of variable interest entities and membership interests of variable interest entities subject to mandatory redemption. Creditors of the VIEs have no recourse to the general credit of TVA. TVA does not have any obligations to provide financial support to the VIEs other than as prescribed in the terms of the agreements related to these transactions.

Other Long-Term Liabilities

Other Long-Term Liabilities	6 Months Ended
	Mar. 31, 2017
Other Liabilities, Noncurrent [Abstract]
Other Long-Term Liabilities	Other Long-Term Liabilities Other long-term liabilities consist primarily of liabilities related to certain derivative instruments as well as liabilities under agreements related to compliance with certain environmental regulations (see Note 16 — Legal Proceedings — Environmental Agreements ). The table below summarizes the types and amounts of Other long-term liabilities: Other Long-Term Liabilities At March 31, 2017 At September 30, 2016 Interest rate swap liabilities $ 1,479 $ 1,938 Capital lease obligations 179 177 Currency swap liabilities 145 162 EnergyRight ® financing obligation 125 130 Membership interests of VIE subject to mandatory redemption 31 33 Commodity contract derivative liabilities 33 49 Environmental agreements liability 14 18 Other 312 269 Total other long-term liabilities $ 2,318 $ 2,776 EnergyRight ® Financing Obligation . TVA purchases certain loans receivable from its LPCs in association with the EnergyRight ® Solutions program. The current and long-term portions of the resulting financing obligation are reported in Accounts payable and accrued liabilities and Other long-term liabilities, respectively, on TVA’s consolidated balance sheets. As of March 31, 2017 , and September 30, 2016 , the carrying amount of the financing obligation reported in Accounts payable and accrued liabilities was approximately $31 million and $ 33 million , respectively. See Note 5 for information regarding the associated loans receivable and for details regarding the EnergyRight ® Solutions program.

Asset Retirement Obligations

Asset Retirement Obligations	6 Months Ended
	Mar. 31, 2017
Asset Retirement Obligation Disclosure [Abstract]
Asset Retirement Obligations	Asset Retirement Obligations During the six months ended March 31, 2017 , TVA's total ARO liability increased $ 63 million as a result of revisions in estimates and periodic accretion, partially offset by settlement projects that were conducted during these periods. The nuclear and non-nuclear accretion expense was deferred as regulatory assets. During the six months ended March 31, 2017 , $ 72 million of the related regulatory assets were amortized into expense as these amounts were collected in rates. See Note 6 . TVA maintains investment trusts to help fund its decommissioning obligations. See Note 13 and Note 16 — Contingencies — Decommissioning Costs for a discussion of the trusts' objectives and the current balances of the trusts. Asset Retirement Obligation Activity Nuclear Non-Nuclear Total Balance at September 30, 2016 $ 2,492 $ 1,560 $ 4,052 Settlements — (58 ) (58 ) Revisions in estimate — 46 46 Additional obligations — 1 1 Accretion (recorded as regulatory asset) 58 16 74 Balance at March 31, 2017 $ 2,550 $ 1,565 $ 4,115 (1 ) Note (1) The current portion of ARO in the amount of $ 200 million and $ 212 million is included in Accounts payable and accrued liabilities at March 31, 2017 , and September 30, 2016 , respectively.

Debt and Other Obligations

Debt and Other Obligations	6 Months Ended
	Mar. 31, 2017
Debt Disclosure [Abstract]
Debt and Other Obligations	Debt and Other Obligations Debt Outstanding Total debt outstanding at March 31, 2017 , and September 30, 2016 , consisted of the following: Debt Outstanding At March 31, 2017 At September 30, 2016 Short-term debt Short-term debt, net $ 815 $ 1,407 Current maturities of power bonds 1,681 1,555 Current maturities of long-term debt of variable interest entities 35 35 Current maturities of notes payable 28 27 Total current debt outstanding, net 2,559 3,024 Long-term debt Long-term power bonds (1) 21,384 21,063 Long-term debt of variable interest entities 1,193 1,211 Long-term notes payable 21 48 Unamortized discounts, premiums, issue costs, and other (170 ) (174 ) Total long-term debt, net 22,428 22,148 Total outstanding debt $ 24,987 $ 25,172 Note (1) Includes net exchange gain from currency transactions of $ 176 million at March 31, 2017 , and $ 150 million at September 30, 2016 . Debt Securities Activity The table below summarizes the long-term debt securities activity for the period from October 1, 2016, to March 31, 2017 : Debt Securities Activity Date Amount (1) Interest Rate Issues 2017 Series A (2) February 2017 $ 1,000 2.88 % Discount on debt issues (1 ) Total long-term debt issuances $ 999 Redemptions/Maturities electronotes ® First Quarter 2017 $ 1 2.65 % electronotes ® Second Quarter 2017 1 3.29 % 2009 Series B December 2016 1 3.77 % 2001 Series D December 2016 525 4.88 % Total redemptions/maturities of power bonds 528 Notes payable 26 0.81 % Debt of variable interest entities 17 4.30 % Total redemptions/maturities of debt $ 571 Note (1) All redemptions were at 100 percent of par. (2) The 2017 Series A bonds were issued at 99.9 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 2017 with a maturity date of September 30, 2017. 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 March 31, 2017 . 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 four long-term revolving credit facilities totaling $ 2.7 billion : a $150 million credit facility matures on December 12, 2019, a $ 500 million credit facility matures on February 1, 2021, a $ 1.0 billion credit facility matures on June 2, 2020, and another $ 1.0 billion credit facility matures on September 30, 2020. The interest rate on any borrowing under these facilities varies based on market factors and the rating of TVA's senior unsecured, long-term, non-credit-enhanced debt. TVA is required to pay an unused facility fee on the portion of the total $ 2.7 billion that TVA has not borrowed or committed under letters of credit. This fee, along with letter of credit fees, may fluctuate depending on the rating of TVA's senior unsecured, long-term, non-credit-enhanced debt. At March 31, 2017 , and September 30, 2016 , there were approximately $1.1 billion and $ 1.4 billion , respectively, of letters of credit outstanding under the facilities. See Note 12 — Other Derivative Instruments — Collateral . The following table provides additional information regarding TVA's funding available under the four long-term credit facilities: Summary of Long-Term Credit Facilities At March 31, 2017 Maturity Date Facility Limit Letters of Credit Outstanding Cash Borrowings Availability December 2019 $ 150 $ 38 $ — $ 112 February 2021 500 500 — — June 2020 1,000 278 — 722 September 2020 1,000 288 — 712 Total $ 2,650 $ 1,104 $ — $ 1,546 Lease/Leaseback Obligations TVA previously entered into leasing transactions to obtain third-party financing for 24 peaking combustion turbine units (“CTs”) as well as certain qualified technological equipment and software (collectively, “QTE”). Due to TVA’s continuing involvement with the combustion turbine facilities and the QTE during the leaseback term, TVA accounted for the lease proceeds as financing obligations. In 2016, TVA acquired 100 percent of the equity interests in two special purpose entities ("SPEs") created for the purpose of facilitating a portion of the leaseback arrangements. As a result of the acquisition, TVA effectively settled its leaseback obligations related to eight CTs. At March 31, 2017 , and September 30, 2016 , the outstanding leaseback obligations related to CTs and QTE were $431 million and $467 million , respectively.

Accumulated Other Comprehensive

Accumulated Other Comprehensive Income (Loss)	6 Months Ended
	Mar. 31, 2017
Equity [Abstract]
Accumulated Other Comprehensive Income (Loss)	Accumulated Other Comprehensive Income (Loss) Accumulated other comprehensive income (loss) ("AOCI") represents market valuation adjustments related to TVA’s currency swaps. The currency swaps are cash flow hedges and are the only derivatives in TVA’s portfolio that have been designated and qualify for hedge accounting treatment. TVA records exchange rate gains and losses on its foreign currency-denominated debt in net income and marks its currency swap assets and liabilities to market through other comprehensive income (loss) ("OCI") . TVA then reclassifies an amount out of AOCI into net income, offsetting the exchange gain/loss recorded on the debt. During the three months ended March 31, 2017 and 2016 , TVA reclassified $ 12 million of gains and $ 22 million of losses, respectively, related to its cash flow hedges from AOCI to Interest expense. During the six months ended March 31, 2017 and 2016 , TVA reclassified $ 26 million and $ 46 million of losses, respectively, related to its cash flow hedges from AOCI to Interest expense. TVA records certain assets and liabilities that result from the regulated ratemaking process that would not be recorded under GAAP for non-regulated entities. As such, certain items that would generally be reported in AOCI or that would impact the statements of operations are recorded as regulatory assets or regulatory liabilities. See Note 6 for a schedule of regulatory assets and liabilities. See Note 12 for a discussion of the recognition in AOCI of gains and losses associated with certain derivative contracts. See Note 13 for a discussion of the recognition of certain investment fund gains and losses as regulatory assets and liabilities. See Note 15 for a discussion of the regulatory accounting related to components of TVA’s benefit plans.

Risk Management Activities and

Risk Management Activities and Derivative Transactions	6 Months Ended
	Mar. 31, 2017
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 has suspended its Financial Trading Program ("FTP") and no longer uses financial instruments to hedge risks related to commodity prices; however, TVA plans to continue to manage fuel price volatility through other methods and to periodically reevaluate its suspended FTP program for 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 Six Months Ended Derivatives in Cash Flow Hedging Relationship Objective of Hedge Transaction Accounting for Derivative Hedging Instrument 2017 2016 2017 2016 Currency swaps To protect against changes in cash flows caused by changes in foreign currency exchange rates (exchange rate risk) Unrealized gains and losses are recorded in AOCI and reclassified to interest expense to the extent they are offset by gains and losses on the hedged transaction. $ 25 $ (27 ) $ 17 $ (54 ) Summary of Derivative Instruments That Receive Hedge Accounting Treatment (part 2) (1) Amount of Gain (Loss) Reclassified from OCI to Interest Expense Three Months Ended Six Months Ended Derivatives in Cash Flow Hedging Relationship 2017 2016 2017 2016 Currency swaps $ 12 $ (22 ) $ (26 ) $ (46 ) Note (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 $ 15 million of gains from AOCI to interest expense within the next twelve months to offset amounts anticipated to be recorded in interest expense related to net 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 March 31 ( 1) Six Months Ended March 31 (1) Derivative Type Objective of Derivative Accounting for Derivative Instrument 2017 2016 2017 2016 Interest rate swaps To fix short-term debt variable rate to a fixed rate (interest rate risk) Mark-to-market gains and losses are recorded as regulatory assets or liabilities. Realized gains and losses are recognized in interest expense when payments are made or received on the swap settlement dates. $ (26 ) $ (27 ) $ (52 ) $ (55 ) 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. 2 — — — Commodity derivatives under 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. (6 ) (21 ) (21 ) (56 ) Note (1) All of TVA's derivative instruments that do not receive hedge accounting treatment have unrealized gains (losses) that would otherwise be recognized in income but instead are deferred as regulatory assets and liabilities. As such, there was no related gain (loss) recognized in income for these unrealized gains (losses) for the three months and six months ended March 31, 2017 and 2016 . Fair Values of TVA Derivatives At March 31, 2017 At September 30, 2016 Derivatives That Receive Hedge Accounting Treatment Balance Balance Sheet Presentation Balance Balance Sheet Presentation Currency swaps £200 million Sterling $ (84 ) Other long-term liabilities $ (82 ) Other long-term liabilities £250 million Sterling (34 ) Other long-term liabilities (41 ) Other long-term liabilities £150 million Sterling (27 ) Other long-term liabilities (39 ) Other long-term liabilities At March 31, 2017 At September 30, 2016 Derivatives That Do Not Receive Hedge Accounting Treatment Balance Balance Sheet Presentation Balance Balance Sheet Presentation Interest rate swaps $1.0 billion notional (1,072 ) Other long-term liabilities (1,387 ) Other long-term liabilities $476 million notional (398 ) Other long-term liabilities (539 ) Other long-term liabilities $42 million notional (9 ) Other long-term liabilities (12 ) Other long-term liabilities Commodity contract derivatives (97 ) Other current assets $25; Other long-term liabilities $(33); Accounts payable and accrued liabilities $(89) (125 ) Other current assets $6; Other long-term assets $3; Other long-term liabilities $(49); Accounts payable and accrued liabilities $(85) FTP Derivatives under FTP (1) (17 ) Other current assets $(13); Accounts payable and accrued liabilities $(4) (39 ) Other current assets $(30); Other long-term liabilities $(2); Accounts payable and accrued liabilities $(7) Note (1) Fair values of certain derivatives under the FTP that were in net liability positions totaling $13 million and $30 million at March 31, 2017 , and September 30, 2016 , 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 three currency swaps outstanding as of March 31, 2017 , with total currency exposure of £600 million and expiration dates ranging from 2021 to 2043 . 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 . Generally, TVA uses interest rate swaps to fix variable short-term debt to a fixed rate, and TVA uses regulatory accounting treatment to defer the mark-to-market ("MtM") gains and losses on its interest rate swaps. The net deferred unrealized gains and losses are classified as regulatory 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 March 31, 2017 and 2016 , the changes in fair market value of the interest rate swaps resulted in deferred unrealized gains of $ 18 million and deferred unrealized losses of $ 262 million , respectively. For the six months ended March 31, 2017 and 2016 , the changes in fair market value of the interest rate swaps resulted in deferred unrealized gains of $ 459 million and deferred unrealized losses of $ 173 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 March 31, 2017 , TVA's coal contract derivatives had terms of up to two years and natural gas contract derivatives had terms of up to four years. Commodity Contract Derivatives At March 31, 2017 At September 30, 2016 Number of Contracts Notional Amount Fair Value (MtM) Number of Contracts Notional Amount Fair Value ( MtM ) Coal contract derivatives 19 21 million tons $ (113 ) 20 20 million tons $ (127 ) Natural gas contract derivatives 48 278 million mmBtu $ 16 39 148 million mmBtu $ 2 Derivatives Under FTP. While TVA has suspended its FTP and no longer uses financial instruments to hedge risks related to commodity prices, certain natural gas swaps with a maturity of one year or less remain as part of the suspended FTP. Derivatives Under Financial Trading Program (1) At March 31, 2017 At September 30, 2016 Notional Amount Fair Value (MtM) (in millions) Notional Amount Fair Value (MtM) (in millions) Natural gas (in mmBtu) Swap contracts 11,200,000 $ (17 ) 21,052,500 $ (39 ) Note (1) Fair value amounts presented are based on the net commodity position with the counterparty. Notional amounts disclosed represent the net value of contractual amounts. TVA defers all 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 $ (2) million at March 31, 2017 , and $ (5) million at September 30, 2016 . 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 March 31 2017 At September 30 2016 FTP unrealized gains (losses) deferred as regulatory liabilities (assets) Natural gas $ (17 ) $ (39 ) Financial Trading Program Realized Gains (Losses) Three Months Ended Six Months Ended 2017 2016 2017 2016 Decrease (increase) in fuel expense Natural gas $ (5 ) $ (17 ) $ (17 ) $ (45 ) Financial Trading Program Realized Gains (Losses) Three Months Ended Six Months Ended 2017 2016 2017 2016 Decrease (increase) in purchased power expense Natural gas $ (1 ) $ (4 ) $ (4 ) $ (11 ) Offsetting of Derivative Assets and Liabilities The amounts of TVA's derivative instruments as reported in the consolidated balance sheets as of March 31, 2017 , and September 30, 2016 , are shown in the table below: Derivative Assets and Liabilities As of March 31, 2017 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 Commodity derivatives not subject to master netting or similar arrangement $ 25 $ — $ 25 Liabilities Currency swap(s) (3) $ 145 $ — $ 145 Interest rate swaps (3) 1,479 — 1,479 Commodity derivatives under FTP 17 (13 ) 4 Total derivatives subject to master netting or similar arrangement 1,641 (13 ) 1,628 Commodity derivatives not subject to master netting or similar arrangement 122 — 122 Total liabilities $ 1,763 $ (13 ) $ 1,750 As of September 30, 2016 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 Commodity derivatives under FTP subject to master netting or similar arrangement $ 6 $ (6 ) $ — Commodity derivatives not subject to master netting or similar arrangement 9 — 9 Total $ 15 $ (6 ) $ 9 Liabilities Currency swap(s) (3) $ 162 $ — $ 162 Interest rate swaps (3) 1,938 — 1,938 Commodity derivatives under FTP 45 (36 ) 9 Total derivatives subject to master netting or similar arrangement 2,145 (36 ) 2,109 Commodity derivatives not subject to master netting or similar arrangement 134 — 134 Total $ 2,279 $ (36 ) $ 2,243 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 that are not offset in the consolidated balance sheets. (3) Letters of credit of approximately $ 1.1 billion and $ 1.4 billion were posted as collateral at March 31, 2017 , and September 30, 2016 , 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. Other Derivative Instruments Investment Fund Derivatives . Investment funds consist primarily of funds held in the Nuclear Decommissioning Trust ("NDT") , the Asset Retirement Trust ("ART") , the Supplemental Executive Retirement Plan ("SERP") , and the Long-Term Deferred Compensation Plan ("LTDCP") . All securities in the trusts are classified as trading. See Note 13 — Investment Funds for a discussion of the trusts' objectives and the types of investments included in the various trusts. These trusts may invest in derivative instruments which may include swaps, futures, options, forwards, and other instruments. The fair values of these derivatives were in net asset positions totaling $10 million and $ 15 million at March 31, 2017 and September 30, 2016 , respectively. 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 March 31, 2017 , the aggregate fair value of all derivative instruments with credit-risk related contingent features that were in a liability position was $ 1.6 billion . TVA's collateral obligations at March 31, 2017 , under these arrangements were approximately $ 1.1 billion , for which TVA had posted approximately $1.1 billion in letters of credit. These letters of credit reduce the available balance under the related credit facilities. TVA's assessment of the risk of its nonperformance includes a reduction in its exposure under the contract as a result of this posted collateral. For all of its derivative instruments with credit-risk related contingent features: • If TVA remains a majority-owned U.S. government entity but Standard & Poor's Financial Services, LLC ("S&P") or Moody's Investors Service, Inc. ("Moody's") downgrades TVA's credit rating to AA or Aa2, respectively, TVA's collateral obligations would likely increase by $ 22 million , and • If TVA ceases to be majority-owned by the U.S. government, TVA's credit rating would likely be downgraded and TVA would be required to post additional collateral. Counterparty Risk TVA may be exposed to certain risks when a counterparty has the potential to fail to meet its obligations in accordance with agreed terms. These risks may be related to credit, operational, or nonperformance matters. To mitigate certain counterparty risk, TVA analyzes the counterparty’s financial condition prior to entering into an agreement, establishes credit limits, monitors the appropriateness of those limits, as well as any changes in the creditworthiness of the counterparty, on an ongoing basis, and when required, employs credit mitigation measures, such as collateral or prepayment arrangements and master purchase and sale agreements, to mitigate credit risk. TVA believes its policies and procedures for counterparty performance risk reviews have generally protected TVA against significant exposure related to market and economic conditions. Customers . TVA is exposed to counterparty credit risk associated with trade accounts receivable from delivered power sales to LPCs, and from industries and federal agencies directly served, all located in the Tennessee Valley region. TVA is also exposed to risk from exchange power arrangements with a small number of investor-owned regional utilities related to either delivered power or the replacement of open positions of longer-term purchased power or fuel agreements. See Note 1 — Allowance for Uncollectible Accounts and Note 3 . 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. Nuclear fuel requirements, including uranium mining and milling, conversion services, enrichment services, and fabrication services, are met from various suppliers, depending on the type of service. TVA purchases the majority of its natural gas requirements from a variety of suppliers under short-term contracts. To help ensure a reliable supply of coal, TVA had coal contracts with multiple suppliers at March 31, 2017 . The contracted supply of coal is sourced from multiple geographic regions of the United States and is to be delivered via various transportation methods (i.e., barge, rail, and truck). Emerging technologies, environmental regulations, and low natural gas prices have contributed to weak demand for coal. As a result, coal suppliers are facing increased financial pressure, which has led to relatively poor credit ratings and bankruptcies. Continued difficulties by coal suppliers could result in consolidations, additional bankruptcies, restructurings, contract renegotiations, or other scenarios. Under these scenarios and TVA’s potential available responses, TVA does not anticipate a significant financial impact in obtaining continued fuel supply for its coal-fired generation. On March 29, 2017, one of TVA’s suppliers filed for protection under Chapter 11 of the United States Bankruptcy Code. Subsequently, on April 11, 2017, the parent company of the supplier submitted an unaudited financial report for the period from April 2016 to December 2016 with an accompanying statement warning "there are events and circumstances that may bring about significant questions about the idea of carrying on as a going concern." The parent company is also a supplier of goods and services to TVA. TVA currently has several contracts with these companies, including contracts for the enrichment and fabrication of nuclear fuel and the manufacture of a steam generator, as well as several ongoing agreements for maintenance and outage support at its nuclear and coal-fired plants. TVA is assessing potential performance impacts, including procurement of parts and services as well as outage schedules. If either supplier is unable to perform under TVA’s existing contracts and TVA is unable to obtain similar services at similar terms from other vendors, TVA could experience delays, disruptions, additional costs, or other operational outcomes which TVA cannot predict at this time, but which could be material. 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. Derivative Counterparties . TVA has entered into physical and financial contracts that qualify as derivatives for hedging purposes, and TVA's NDT fund and qualified defined benefit pension plan have entered into derivative contracts for investment purposes. If a counterparty to one of TVA's hedging transactions defaults, TVA might incur substantial costs in connection with entering into a replacement hedging transaction. If a counterparty to the derivative contracts into which the NDT fund and the qualified 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 March 31, 2017 , all of TVA's commodity derivatives under the FTP, currency swaps, and interest rate swaps were with banking counterparties whose Moody's credit ratings were A3 or higher. TVA classifies qualified forward coal and natural gas contracts as derivatives. See Derivatives Not Receiving Hedge Accounting Treatment above. At March 31, 2017 , the coal contracts were with counterparties whose Moody's credit rating, or TVA’s internal analysis when such information was unavailable, ranged from Ca or D , respectively, to Ba3 . At March 31, 2017 , the natural gas contracts were with counterparties whose ratings ranged from B1 to A3 . See Suppliers above for discussion of challenges facing the coal industry. TVA's total value for derivative contracts with coal counterparties in an asset position as of March 31, 2017 , was approximately $3 million . 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.

Fair Value Measurements

Fair Value Measurements	6 Months Ended
	Mar. 31, 2017
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements Fair value is determined based on the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the asset or liability's principal market, or in the absence of a principal market, the most advantageous market for the asset or liability in an orderly transaction between market participants. TVA uses market or observable inputs as the preferred source of values, followed by assumptions based on hypothetical transactions in the absence of market inputs. Valuation Techniques The measurement of fair value results in classification into a hierarchy by the inputs used to determine the fair value as follows: Level 1 — Unadjusted quoted prices in active markets accessible by the reporting entity for identical assets or liabilities. Active markets are those in which transactions for the asset or liability occur with sufficient frequency and volume to provide pricing. Level 2 — Pricing inputs other than quoted market prices included in Level 1 that are based on observable market data and that are directly or indirectly observable for substantially the full term of the asset or liability. These include quoted market prices for similar assets or liabilities, quoted market prices for identical or similar assets in markets that are not active, adjusted quoted market prices, inputs from observable data such as interest rate and yield curves, volatilities and default rates observable at commonly quoted intervals, and inputs derived from observable market data by correlation or other means. Level 3 — Pricing inputs that are unobservable, or less observable, from objective sources. Unobservable inputs are only to be used to the extent observable inputs are not available. These inputs maintain the concept of an exit price from the perspective of a market participant and should reflect assumptions of other market participants. An entity should consider all market participant assumptions that are available without unreasonable cost and effort. These are given the lowest priority and are generally used in internally developed methodologies to generate management's best estimate of the fair value when no observable market data is available. A financial instrument's level within the fair value hierarchy (where Level 1 is the highest and Level 3 is the lowest) is based on the lowest level of input significant to the fair value measurement. The following sections describe the valuation methodologies TVA uses to measure different financial instruments at fair value. Except for gains and losses on SERP and LTDCP assets, all changes in fair value of these assets and liabilities have been recorded as changes in regulatory assets, regulatory liabilities, or AOCI on TVA's consolidated balance sheets and consolidated statements of comprehensive income (loss). Except for gains and losses on SERP and LTDCP assets, there has been no impact to the consolidated statements of operations or the consolidated statements of cash flows related to these fair value measurements. Investment Funds At March 31, 2017 , Investment funds were composed of $ 2.4 billion of securities classified as trading and measured at fair value. Trading securities are held in the NDT, ART, SERP, and LTDCP. The NDT holds funds for the ultimate decommissioning of TVA's nuclear power plants. The ART holds funds primarily for the costs related to the future closure and retirement of TVA's other long-lived assets. The balances in the NDT and ART were $ 1.8 billion and $ 545 million , respectively, at March 31, 2017 . 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. NDT and SERP funds are invested in portfolios of securities generally designed to achieve a return in line with overall equity market performance, and ART and LTDCP funds are invested in portfolios of securities generally designed to achieve a return in line with overall debt and equity market performance. The NDT, ART, SERP, and LTDCP are composed of multiple types of investments and are managed by external institutional managers. Most U.S. and international equities, U.S. Treasury inflation-protected securities, real estate investment trust securities, and cash securities and certain derivative instruments are measured based on quoted exchange prices in active markets and are classified as Level 1 valuations. Fixed-income investments, high-yield fixed-income investments, currencies, and most derivative instruments are non-exchange traded and are classified as Level 2 valuations. These measurements are based on market and income approaches with observable market inputs. Private equity limited partnerships and private real estate investments may include holdings of investments in private real estate, venture capital, buyout, mezzanine or subordinated debt, restructuring or distressed debt, and special situations through funds managed by third-party investment managers. These investments generally involve a three -to- four -year period where the investor contributes capital, followed by a period of distribution, typically over several years. The investment period is generally, at a minimum, 10 years or longer. The NDT had unfunded commitments related to private equity limited partnerships of $ 59 million and unfunded commitments related to private real estate of $ 5 million at March 31, 2017 . These investments have no redemption or limited redemption options and may also impose restrictions on the NDT’s ability to liquidate its investments. 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 equity limited partnerships and private real estate investments are valued at net asset values ("NAV") as a practical expedient for fair value. TVA classifies its interest in these types of investments as investments measured at net asset value in the fair value hierarchy. Commingled funds represent investment funds comprising multiple individual financial instruments. The commingled funds held by the NDT, ART, SERP, and LTDCP consist of either a single class of securities, such as equity, debt, or foreign currency securities, or multiple classes of securities. All underlying positions in these commingled funds are either exchange traded or measured using observable inputs for similar instruments. The fair value of commingled funds is based on NAV per fund share (the unit of account), derived from the prices of the underlying securities in the funds. These commingled funds can be redeemed at the measurement date NAV and are classified as Commingled funds measured at net asset value in the fair value hierarchy. Realized and unrealized gains and losses on trading securities are recognized in current earnings and are based on average cost. The gains and losses of the NDT and ART are subsequently reclassified to a regulatory asset or liability account in accordance with TVA's regulatory accounting policy. See Note 1 — Cost-Based Regulation . TVA recorded unrealized gains and losses related to its trading securities held during each period as follows: Unrealized Investment Gains (Losses) Three Months Ended Six Months Ended Fund Financial Statement Presentation 2017 2016 2017 2016 SERP Other income (expense) $ 2 $ — $ 1 $ — LTDCP Other income (expense) 1 — — — NDT Regulatory asset 42 9 35 48 ART Regulatory asset 19 (3 ) 22 9 Currency and Interest Rate Derivatives See Note 12 — Cash Flow Hedging Strategy for Currency Swaps and Derivatives Not Receiving Hedge Accounting Treatment for a discussion of the nature, purpose, and contingent features of TVA's currency swaps and interest rate swaps. These swaps are classified as Level 2 valuations and are valued based on income approaches using observable market inputs for similar instruments. Commodity Contract Derivatives and Commodity Derivatives Under FTP Commodity Contract Derivatives. Most of these contracts are valued based on market approaches which utilize short- and mid-term market-quoted prices from an external industry brokerage service. A small number of these contracts are valued based on a pricing model using long-term price estimates from TVA's coal price forecast. To value the volume option component of applicable coal contracts, TVA uses a Black-Scholes pricing model which includes inputs from the forecast, contract-specific terms, and other market inputs. These contracts are classified as Level 3 valuations. Commodity Derivatives Under FTP. These contracts are valued based on market approaches which utilize Chicago Mercantile Exchange ("CME") quoted prices and other observable inputs. Swap contracts are valued using a pricing model based on CME inputs and are subject to nonperformance risk outside of the exit price. These contracts are classified as Level 2 valuations. See Note 12 — Derivatives Not Receiving Hedge Accounting Treatment — Commodity Derivatives and — Derivatives Under FTP for a discussion of the nature and purpose of coal contracts and derivatives under TVA's FTP. Nonperformance Risk The assessment of nonperformance risk, which includes credit risk, considers changes in current market conditions, readily available information on nonperformance risk, letters of credit, collateral, other arrangements available, and the nature of master netting arrangements. TVA is a counterparty to currency swaps, interest rate swaps, commodity contracts, and other derivatives which subject TVA to nonperformance risk. Nonperformance risk on the majority of investments and certain exchange-traded instruments held by TVA is incorporated into the exit price that is derived from quoted market data that is used to mark the investment to market. Nonperformance risk for most of TVA's derivative instruments is an adjustment to the initial asset/liability fair value. TVA adjusts for nonperformance risk, both of TVA (for liabilities) and the counterparty (for assets), by applying credit valuation adjustments ("CVAs") . TVA determines an appropriate CVA for each applicable financial instrument based on the term of the instrument and TVA's or the counterparty's credit rating as obtained from Moody's. For companies that do not have an observable credit rating, TVA uses internal analysis to assign a comparable rating to the counterparty. TVA discounts each financial instrument using the historical default rate (as reported by Moody's for CY 1983 to CY 2016) 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 $ 1 million decrease in the fair value of assets and a less than $ 1 million decrease in the fair value of liabilities at March 31, 2017 . 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 March 31, 2017 , and September 30, 2016 . 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 March 31, 2017 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 $ 205 $ — $ — $ 205 Government debt securities 76 58 — 134 Corporate debt securities — 408 — 408 Mortgage and asset-backed securities — 46 — 46 Institutional mutual funds 83 — — 83 Forward debt securities contracts — 10 — 10 Private equity funds measured at net asset value (1) — — — 139 Private real estate funds measured at net asset value (1) — — — 112 Commingled funds measured at net asset value (1) — — — 1,251 Total investments 364 522 — 2,388 Commodity contract derivatives — 22 3 25 Total $ 364 $ 544 $ 3 $ 2,413 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) $ — $ 145 $ — $ 145 Interest rate swaps — 1,479 — 1,479 Commodity contract derivatives — 6 116 122 Commodity derivatives under FTP (2) Swap contracts — 4 — 4 Total $ — $ 1,634 $ 116 $ 1,750 Notes (1) Certain investments that are measured at fair value using the net asset value per share (or its equivalent) practical expedient have not been categorized in the fair value hierarchy. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the amounts presented in the consolidated balance sheets. (2) Due to the right of setoff and method of settlement, TVA elects to record commodity derivatives under the FTP based on its net commodity position with the counterparty or FCM. Deposits are made to TVA's margin cash accounts held with each FCM to offset any net liability positions in full for derivatives that are transacted with FCMs. TVA records currency swaps net of cash collateral received from or paid to the counterparty, to the extent such amount is not recorded in Accounts payable and accrued liabilities. See Note 12 — Offsetting of Derivative Assets and Liabilities . Fair Value Measurements At September 30, 2016 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 $ 196 $ — $ — $ 196 Government debt securities 88 36 — 124 Corporate debt securities — 393 — 393 Mortgage and asset-backed securities — 50 — 50 Institutional mutual funds 92 — — 92 Forward debt securities contracts — 15 — 15 Private equity funds measured at net asset value (1) — — — 132 Private real estate funds measured at net asset value (1) — — — 113 Commingled funds measured at net asset value (1) — — — 1,142 Total investments 376 494 — 2,257 Commodity contract derivatives — 5 4 9 Total $ 376 $ 499 $ 4 $ 2,266 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) $ — $ 162 $ — $ 162 Interest rate swaps — 1,938 — 1,938 Commodity contract derivatives — 3 131 134 Commodity derivatives under FTP (2) Swap contracts — 9 — 9 Total $ — $ 2,112 $ 131 $ 2,243 Notes (1) Certain investments that are measured at fair value using the net asset value per share (or its equivalent) practical expedient have not been categorized in the fair value hierarchy. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the amounts presented in the consolidated balance sheets. (2) Due to the right of setoff and method of settlement, TVA elects to record commodity derivatives under the FTP based on its net commodity position with the counterparty or FCM. Deposits are made to TVA's margin cash accounts held with each FCM to offset any net liability positions in full for derivatives that are transacted with FCMs. TVA records currency swaps net of cash collateral received from or paid to the counterparty, to the extent such amount is not recorded in Accounts payable and accrued liabilities. See Note 12 — Offsetting of Derivative Assets and Liabilities . TVA uses internal valuation specialists for the calculation of its commodity contract derivatives fair value measurements classified as Level 3. Analytical testing is performed on the change in fair value measurements each period to ensure the valuation is reasonable based on changes in general market assumptions. Significant changes to the estimated data used for unobservable inputs, in isolation or combination, may result in significant variations to the fair value measurement reported. The following table presents a reconciliation of all commodity contract derivatives measured at fair value on a recurring basis using significant unobservable inputs (Level 3): Fair Value Measurements Using Significant Unobservable Inputs Commodity Contract Derivatives Three Months Ended Six Months Ended Balance at beginning of period $ (123 ) $ (98 ) Net unrealized gains (losses) deferred as regulatory assets and liabilities (64 ) (89 ) Balance at March 31, 2016 $ (187 ) $ (187 ) Balance at beginning of period $ (104 ) $ (127 ) Net unrealized gains (losses) deferred as regulatory assets and liabilities (8 ) 15 Balance at March 31, 2017 $ (112 ) $ (112 ) 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 March 31 2017 Valuation Technique(s) Unobservable Inputs Range Assets Commodity contract derivatives $ 3 Pricing model Coal supply and demand 0.6 - 0.8 billion tons/year Long-term market prices $11.45 - $109.55/ton Liabilities Commodity contract derivatives $ 116 Pricing model Coal supply and demand 0.6 - 0.8 billion tons/year Long-term market prices $11.45 - $109.55/ton Quantitative Information about Level 3 Fair Value Measurements Fair Value at September 30 2016 Valuation Technique(s) Unobservable Inputs Range Assets Commodity contract derivatives $ 4 Pricing model Coal supply and demand 0.7 - 0.8 billion tons/year Long-term market prices $11.80 - $85.02/ton Liabilities Commodity contract derivatives $ 131 Pricing model Coal supply and demand 0.7 - 0.8 billion tons/year Long-term market prices $11.80 - $85.02/ton Other Financial Instruments Not Recorded at Fair Value TVA uses the methods and assumptions described below to estimate the fair value of each significant class of financial instrument. The fair values of the financial instruments held at March 31, 2017 , and September 30, 2016 , may not be representative of the actual gains or losses that will be recorded when these instruments mature or are called or presented for early redemption. The estimated values of TVA's financial instruments not recorded at fair value at March 31, 2017 , and September 30, 2016 , were as follows: Estimated Values of Financial Instruments Not Recorded at Fair Value At March 31, 2017 At September 30, 2016 Valuation Classification Carrying Amount Fair Value Carrying Amount Fair Value EnergyRight ® receivables (including current portion) Level 2 $ 135 $ 138 $ 141 $ 144 Loans and other long-term receivables, net (including current portion) Level 2 $ 161 $ 150 $ 141 $ 130 EnergyRight ® financing obligation (including current portion) Level 2 $ 156 $ 175 $ 163 $ 183 Unfunded loan commitments Level 2 $ — $ 14 $ — $ 17 Membership interest of variable interest entity subject to mandatory redemption (including current portion) Level 2 $ 33 $ 42 $ 35 $ 46 Long-term outstanding power bonds (including current maturities), net Level 2 $ 22,906 $ 26,983 $ 22,456 $ 28,620 Long-term debt of variable interest entities (including current maturities), net Level 2 $ 1,217 $ 1,353 $ 1,234 $ 1,468 Long-term notes payable (including current maturities) Level 2 $ 49 $ 49 $ 75 $ 75 Due to the short-term maturity of Cash and cash equivalents, Restricted cash and investments, and Short-term debt, net (each considered a Level 1 valuation classification), the carrying amounts of these instruments approximate their fair values. The fair value for loans and other long-term receivables is estimated by determining the present value of future cash flows using a discount rate equal to lending rates for similar loans made to borrowers with similar credit ratings and for similar remaining maturities, where applicable. The fair value of long-term debt traded in the public market is determined by multiplying the par value of the debt by the indicative market price at the balance sheet date. The fair value of other long-term debt and membership interests of variable interest entities subject to mandatory redemption is estimated by determining the present value of future cash flows using current market rates for similar obligations, giving effect to credit ratings and remaining maturities.

Other Income (Expense), Net

Other Income (Expense), Net	6 Months Ended
	Mar. 31, 2017
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 Three Months Ended Six Months Ended 2017 2016 2017 2016 External services $ 5 $ 3 $ 8 $ 7 Interest income 6 6 11 12 Gains (losses) on investments 4 — 4 3 Miscellaneous — (1 ) 4 (2 ) Total other income (expense), net $ 15 $ 8 $ 27 $ 20

Benefit Plans

Benefit Plans	6 Months Ended
	Mar. 31, 2017
Compensation and Retirement Disclosure [Abstract]
Benefit Plans	Benefit Plans TVA sponsors a qualified defined benefit pension plan ("pension plan") that covers most of its full-time employees hired before July 1, 2014, a qualified defined contribution plan ("401(k) plan") that covers most of its full-time employees, two unfunded post-retirement health care plans that provide for non-vested contributions toward the cost of eligible retirees' medical coverage, other postemployment benefits, such as workers' compensation, and the SERP. The pension plan and the 401(k) plan are administered by a separate legal entity, the TVA Retirement System ("TVARS"), which is governed by its own board of directors (the "TVARS Board"). The components of net periodic benefit cost and other amounts recognized as changes in regulatory assets for the three and six months ended March 31, 2017 and 2016 , were as follows: Components of TVA’s Benefit Plans For the Three Months Ended March 31 For the Six Months Ended March 31 Pension Benefits Other Post-Retirement Benefits Pension Benefits Other Post-Retirement Benefits 2017 2016 2017 2016 2017 2016 2017 2016 Service cost $ 13 $ 34 $ 5 $ 4 $ 30 $ 66 $ 9 $ 8 Interest cost 116 142 4 8 232 282 11 15 Expected return on plan assets (114 ) (112 ) — — (228 ) (223 ) — — Amortization of prior service credit (24 ) (5 ) (10 ) (2 ) (49 ) (11 ) (11 ) (3 ) Recognized net actuarial loss 120 82 5 1 236 155 7 3 Total net periodic benefit cost as actuarially determined 111 141 4 11 221 269 16 23 Amount capitalized due to actions of regulator (34 ) (71 ) — — (68 ) (129 ) — — Total net periodic benefit cost $ 77 $ 70 $ 4 $ 11 $ 153 $ 140 $ 16 $ 23 TVA contributes to the pension plan such amounts as are necessary on an actuarial basis to provide the pension plan with assets sufficient to meet TVA-funded benefit obligations to be paid to members. TVA contributed $275 million to TVARS in 2016 and expects to contribute $ 300 million in 2017. As of March 31, 2017 , TVA had contributed $150 million to TVARS and expects to contribute the remaining $150 million by September 30, 2017. TVA also contributed $42 million and $20 million to the 401(k) plan during the six months ended March 31, 2017 and 2016 , respectively. TVA does not separately set aside assets to fund its other post-retirement benefit plans, but rather funds such benefits on an as-paid basis. TVA provided approximately $ 17 million and $ 21 million , net of rebates and subsidies, to other post-retirement benefit plans for the six months ended March 31, 2017 and 2016 , respectively. TVA includes its cash contributions to the pension plan in the rate-making formula; accordingly, TVA recognizes pension costs as regulatory assets to the extent that the amount calculated under GAAP as pension expense differs from the amount TVA contributes to the pension plan.

Contingencies and Legal Proceed

Contingencies and Legal Proceedings	6 Months Ended
	Mar. 31, 2017
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 $ 450 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 seven licensed units, TVA could be required to pay a maximum of $ 891 million per nuclear incident, but it would have to pay no more than $ 133 million per incident in any one year. When the contributions of the nuclear plant licensees are added to the insurance proceeds of $ 450 million , over $ 13.0 billion , including a five percent surcharge for legal expenses, would be available. Under the Price-Anderson Act, if the first two layers are exhausted, the U.S. Congress is required to take action to provide additional funds to cover the additional losses. TVA carries property, decommissioning, and decontamination insurance of $ 5.1 billion for its licensed nuclear plants, with up to $ 2.1 billion available for a loss at any one site, to cover the cost of stabilizing or shutting down a reactor after an accident. Some of this insurance, which is purchased from Nuclear Electric Insurance Limited ("NEIL") , may require the payment of retrospective premiums up to a maximum of approximately $ 132 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 $ 37 million . Decommissioning Costs. TVA recognizes legal obligations associated with the future retirement of certain tangible long-lived assets related primarily to coal-fired generating plants and nuclear generating plants, hydroelectric generating plants/dams, transmission structures, and other property-related assets. See Note 9 . Nuclear Decommissioning . Provision for decommissioning costs of nuclear generating units is based on options prescribed by the NRC procedures to dismantle and decontaminate the facilities to meet the NRC criteria for license termination. At March 31, 2017 , the estimated future decommissioning cost of $2.6 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 differences in the underlying assumptions. TVA maintains a NDT to provide funding for the ultimate decommissioning of its nuclear power plants. See Note 13 . TVA monitors the value of its NDT and believes that, over the long term and before cessation of nuclear plant operations and commencement of decommissioning activities, adequate funds from investments and additional contributions, if necessary, will be available to support decommissioning. TVA’s operating nuclear power units are licensed through 2033 - 2055, depending on the unit. It may be possible to extend the operating life of some of the units with approval from the NRC. Non-Nuclear Decommissioning . The estimated future non-nuclear decommissioning ARO was $1.6 billion at March 31, 2017 . This decommissioning cost estimate involves estimating the amount and timing of future expenditures and making judgments concerning whether or not such costs are considered a legal obligation. Estimating the amount and timing of future expenditures includes, among other things, making projections of the timing and duration of the asset retirement process and how costs will escalate with inflation. The actual decommissioning costs may vary from the derived estimates because of changes in current assumptions, such as the assumed dates of decommissioning, changes in regulatory requirements, changes in technology, and changes in the cost of labor, materials, and equipment. TVA maintains an ART to help fund the ultimate decommissioning of its power assets. See Note 13 . Estimates involved in determining if additional funding will be made to the ART include inflation rate, rate of return projections on the fund investments, and the planned use of other sources to fund decommissioning costs. 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. Environmental requirements placed on the operation of TVA’s coal-fired and other generating units will likely continue to become more restrictive over time. 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 existing and future Clean Air Act ("CAA") requirements (excluding greenhouse gas ("GHG") requirements) could lead to costs of approximately $300 million from 2017 to 2023, which include future clean air controls, existing controls capital projects, and air operations and maintenance projects. The majority of the $300 million is expected to be spent by 2018 on new controls at Gallatin and Shawnee. TVA also estimates additional expenditures of $1.1 billion from 2017 to 2022 relating to TVA’s coal combustion residuals ("CCR") conversion program as well as expenditures of approximately $500 million from 2017 to 2024 relating to compliance with Clean Water Act requirements. Future costs could differ from these estimates if new environmental laws or regulations become applicable to TVA or the facilities it operates, or if existing environmental laws or regulations are revised or reinterpreted. There could also be costs that cannot reasonably be predicted at this time, due to uncertainty of actions, that could increase these estimates. 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. On November 22, 2016, the United States District Court for the Eastern District of North Carolina entered a consent decree that resolved all issues associated with the Ward Transformer site. TVA settled all its remaining potential liability for $10 thousand . TVA operations at some facilities have resulted in contamination that TVA is addressing. At March 31, 2017 , and September 30, 2016 , respectively, TVA’s estimated liability for cleanup and similar environmental work for those sites for which sufficient information is available to develop a cost estimate was approximately $27 million and $23 million on a non-discounted basis, and was included in Accounts payable and accrued liabilities and Other long-term liabilities on the Consolidated Balance Sheets. 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 March 31, 2017 , TVA had accrued $ 40 million of probable losses with respect to Legal Proceedings. Of the accrued amount, $ 16 million is included in Other long-term liabilities and $ 24 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, one with the Environmental Protection Agency ("EPA") and the other with Alabama, Kentucky, North Carolina, Tennessee, and three environmental advocacy groups: the Sierra Club, the 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 SO 2 and 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 past claims against TVA based on alleged New Source Review and associated violations were waived and cannot be brought against TVA. Future claims, including those for sulfuric acid mist and GHG emissions, can still be brought against TVA, and claims for increases in particulates can also be pursued at many of TVA’s coal-fired units. Additionally, the Environmental Agreements do not address compliance with new laws and regulations or the cost associated with such compliance. Case Involving Tennessee Valley Authority Retirement System . In March 2010, eight current and former participants in and beneficiaries of TVARS filed suit in the United States District Court for the Middle District of Tennessee challenging the TVARS Board's 2009 decision to amend the TVARS Rules and Regulations (“Rules”) in exchange for a $1.0 billion contribution from TVA. The changes approved by the TVARS Board (1) suspended the TVA contribution requirements for 2010 through 2013, (2) reduced the calculation for cost-of-living adjustments ("COLAs") for CY 2010 through CY 2013, (3) reduced the interest crediting rate for the fixed fund accounts, and (4) increased the eligibility age to receive COLAs from age 55 to 60 . The plaintiffs alleged that these changes violated their constitutional rights (due process, equal protection, and property rights), violated the Administrative Procedure Act, and violated the substantive and procedural components of an anti-cutback provision in the Rules. TVA and the plaintiffs filed cross motions for summary judgment. In August 2015, the court granted TVA’s motion for summary judgment and dismissed the case with prejudice. In September 2015, the plaintiffs appealed this decision to the United States Court of Appeals for the Sixth Circuit (the "Sixth Circuit"). On August 12, 2016, the Sixth Circuit held that the plaintiffs’ rights were not violated because COLAs are not vested benefits. A few other issues were remanded to the district court for further proceedings. On March 2, 2017, the district court granted TVA's motion for a judgment on the administrative record and dismissed all the remaining claims in this case. On March 31, 2017, the plaintiffs appealed the district court's decision to the Sixth Circuit. Cases Involving Gallatin Fossil Plant CCR Facilities. In January 2015, the State of Tennessee filed a lawsuit against TVA in the Chancery Court for Davidson County, Tennessee. The lawsuit alleges that waste materials have been released into waters of the state from 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, which could include an order requiring TVA to relocate the CCR facilities. TDEC is also requesting 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 January 2016, the court issued an agreed temporary injunction proposed by the State of Tennessee and TVA requiring TVA to conduct further environmental studies at Gallatin to determine the extent of soil, surface water, and groundwater contamination by CCR material at the site and to support the development of any necessary corrective action plan in cooperation with the other parties. Pursuant to the injunction, TVA submitted an Environmental Investigation Plan ("EIP") to the State of Tennessee on March 18, 2016. Following State comments on the draft EIP, TVA submitted a revised EIP to the State on June 20, 2016. On June 30, 2016, the State provided conditional approval to proceed with a portion of the investigation. The State subsequently provided additional approvals to proceed with other portions of the investigation. Trial in this action is scheduled to begin in December 2017. In April 2015, TSRA and TCWN filed a separate 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, which could include an order requiring TVA to relocate the CCR facilities. The plaintiffs are also requesting civil penalties of up to $37,500 per violation per day. In June 2015, TVA filed a motion to dismiss the majority of the claims in the federal case based on the State of Tennessee’s diligent prosecution of substantially overlapping claims in its state court action. Since then, TVA has filed several other motions seeking to dismiss all claims in the case on other bases as well. In September 2016, the court ruled on all pending motions. The court held, among other things, that (1) TVA could be liable for civil penalties under the Clean Water Act and (2) the lawsuit could proceed to trial but the court could consider issues only to the extent that they are not being considered in the state court action. In December 2016, the court denied TVA's motion to reconsider the court's decision that TVA could be liable for civil penalties. Trial in this action began on January 30, 2017, and concluded February 2, 2017. The parties made their post-trial filings on April 14, 2017, and the district court is expected to render its decision later this calendar year. The costs associated with relocating the CCR facilities if required to do so by a court could be material, as could be any civil penalties TVA is ordered to pay. Administrative Proceeding Regarding Browns Ferry Nuclear Plant Extended Power Uprate. In September 2016, the Bellefonte Efficiency and Sustainability Team and Mothers Against Tennessee River Radiation requested a hearing and sought to intervene in TVA’s license amendment request for extended power uprates at Browns Ferry Nuclear Plant. The petitioners contend that TVA's application did not correctly report the potential risk from operating at increased power levels. TVA and the NRC staff filed answers opposing the petition to intervene in October 2016. The ASLB rejected the petition to intervene in November 2016. The petitioners appealed the ASLB's decision to the NRC in November 2016. TVA and the NRC staff filed answers opposing the appeal in December 2016, and the petitioners have filed their response. On April 4, 2017, the NRC affirmed the decision of the ASLB, denying the petition to intervene. The petitioners have the right to appeal this decision to a federal district court. Bull Run Fossil Plant Clean Air Act Permit . In September 2015, the Sierra Club and Environmental Integrity Project filed a petition with the EPA requesting that the EPA object to the CAA renewal permit issued by TDEC to TVA for operations at Bull Run. The petitioners alleged that the permit contained impermissibly lax monitoring requirements for opacity. In February 2016, the petitioners sued the EPA for not responding to the petition in a timely manner. In August 2016, the United States District Court for the District of Columbia entered a consent decree requiring the EPA to respond to the petition by November 10, 2016. On November 10, 2016, the EPA granted the petition and ordered TDEC to revise the permit to assure compliance with the opacity limits. TDEC has revised the permit in accordance with the EPA's order and released it for public comments on February 7, 2017. No comments were received and TDEC issued a final permit, which became effective on April 10, 2017. The final permit provides that compliance with the particulate matter ("PM") limit is deemed sufficient to demonstrate compliance with the opacity limit. TVA will continue to meet the PM limit in the permit. Gallatin Fossil Plant Clean Air Act Permit . In August 2016, the Sierra Club filed a petition with the EPA requesting that the EPA object to the CAA renewal permit issued by TDEC to TVA for operations at Gallatin. The petition alleges that the permit (1) contains compliance evaluation requirements for opacity, particulate matter, and fugitive dust that are not as stringent as required, (2) includes allowances for startup, shutdown, and malfunctions that are inconsistent with the CAA, (3) fails to include reporting requirements to ensure compliance with the Environmental Agreements, and (4) contains impermissibly high SO 2 emission limits. The EPA has not yet acted on the petition.

Summary of Significant Accoun23

Summary of Significant Accounting Policies (Policies)	6 Months Ended
	Mar. 31, 2017
Accounting Policies [Abstract]
General	General The Tennessee Valley Authority ("TVA") is a corporate agency and instrumentality of the United States ("U.S.") that was created in 1933 by legislation enacted by the 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 over 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 and public lands to provide recreational opportunities, adequate water supply, improved water quality, cultural and 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.
Fiscal Year	Fiscal Year TVA's fiscal year ends September 30. Years ( 2017 , 2016 , 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. All regulatory asset write offs would be required to be recognized in earnings in the period in which future recovery ceases to be probable.
Basis of Presentation	Basis of Presentation TVA prepares its consolidated interim financial statements in conformity with GAAP for consolidated interim financial information. Accordingly, TVA's consolidated interim financial statements do not include all of the information and notes required by GAAP for annual financial statements. As such, they should be read in conjunction with the audited financial statements for the year ended September 30, 2016 , and the notes thereto, which are contained in TVA's Annual Report on Form 10-K for the year ended September 30, 2016 (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 consolidated interim financial statements. The accompanying consolidated interim financial statements, which have been prepared in accordance with GAAP, include the accounts of TVA, two wholly-owned direct subsidiaries, and three variable interest entities ("VIE") of which TVA is the primary beneficiary. See Note 7 . Intercompany balances and transactions have been eliminated in consolidation.
Use of Estimates	Use of Estimates The preparation of financial statements requires TVA to estimate the effects of various matters that are inherently uncertain as of the date of the consolidated financial statements. Although the consolidated financial statements are prepared in conformity with GAAP, TVA is required to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities, and the amounts of revenues and expenses reported during the reporting period. Each of these estimates varies in regard to the level of judgment involved and its potential impact on TVA's financial results. Estimates are considered critical either when a different estimate could have reasonably been used, or where changes in the estimate are reasonably likely to occur from period to period, and such use or change would materially impact TVA's financial condition, results of operations, or cash flows.
Allowance for Uncollectible Accounts	Allowance for Uncollectible Accounts The allowance for uncollectible accounts reflects TVA's estimate of probable losses inherent in its accounts and loans receivable balances. TVA determines the allowance based on known accounts, historical experience, and other currently available information including events such as customer bankruptcy and/or a customer failing to fulfill payment arrangements. It also reflects TVA's corporate credit department's assessment of the financial condition of customers and the credit quality of the receivables. The allowance for uncollectible accounts was $ 1 million at both March 31, 2017 , and September 30, 2016 , for accounts receivable. Additionally, loans receivable of $ 161 million and $ 141 million at March 31, 2017 , and September 30, 2016 , respectively, are included in Accounts receivable, net and Other long-term assets, for the current and long-term portions, respectively, and reported net of allowances for uncollectible accounts of $ 8 million at both March 31, 2017 , and September 30, 2016 .
Pre-Commercial Plant Operations	Pre-Commercial Plant Operations As part of the process of completing the construction of a generating unit, the electricity produced is used to serve the demands of the electric system. TVA estimates revenue from such pre-commercial generation based on the guidance provided by Federal Energy Regulatory Commission ("FERC") regulations. Watts Bar Nuclear Plant ("Watts Bar") Unit 2 commenced pre-commercial plant operations on June 3, 2016, and commercial operations began on October 19, 2016. TVA has also constructed a natural gas-fired generation facility at its Paradise Fossil Plant site which commenced pre-commercial plant operations on October 10, 2016, and commercial operations on April 7, 2017. Estimated revenue of $ 6 million and $ 20 million , related to these projects, was capitalized to offset project costs and is included in Revenue from sales of electricity as a contra-revenue amount on the consolidated statement of operations for the three and six months ended March 31, 2017 , respectively. TVA also capitalized related fuel costs for these two construction projects of approximately $ 8 million and $ 13 million during the three and six months ended March 31, 2017 , respectively.
Depreciation	Depreciation Depreciation expense was $336 million and $369 million for the three months ended March 31, 2017 and 2016 , respectively, and $ 672 million and $ 733 million for the six months ended March 31, 2017 and 2016 , respectively. Depreciation rates are determined based on an external depreciation study. TVA concluded and implemented the results of a new study effective October 1, 2016. Implementation of the new depreciation rates resulted in an estimated decrease of approximately $ 56 million and $ 112 million in depreciation and amortization expense during the three and six months ended March 31, 2017 , respectively, as compared to the same periods of the prior year. This estimate represents the impact of implementing the new depreciation rates only and does not include any potential impact of other possible changes, including additions to or retirements of net completed plant that occurred during the same period. The decrease in depreciation expense as a result of the new depreciation rates is primarily attributable to the use of TVA's current generation plans, which resulted in changes in retirement date assumptions for coal-fired plants, and changes in the estimated service lives for transmission assets.
Allowance for Funds Used During Construction	Allowance for Funds Used During Construction TVA may capitalize interest on eligible projects as allowance for funds used during construction ("AFUDC") , based on the average interest rate of TVA’s outstanding debt. The allowance is applicable to construction in progress related to eligible projects with (1) an expected total project cost of $ 1.0 billion or more, and (2) an estimated construction period of at least three years in duration. TVA capitalized $ 58 million and $ 116 million of AFUDC for the three and six months ended March 31, 2016 , respectively, related to the Watts Bar Unit 2 project which went into service in October 2016. No AFUDC was recorded for comparable periods in the current year.
Blended Low-Enriched Uranium Program	Blended Low-Enriched Uranium Program Under the blended low-enriched uranium ("BLEU") program, TVA, the U.S. Department of Energy ("DOE") , and certain nuclear fuel contractors have entered into agreements providing for the DOE's surplus of enriched uranium to be blended with other uranium down to a level that allows the blended uranium to be fabricated into fuel that can be used in nuclear power plants. Under the terms of an interagency agreement between TVA and the DOE, in exchange for supplying highly enriched uranium materials to the appropriate third-party fuel processors for processing into usable BLEU fuel for TVA, the DOE participates to a degree in the savings generated by TVA’s use of this blended nuclear fuel. Over the life of the program, TVA projects that the DOE’s share of savings generated by TVA’s use of this blended nuclear fuel could result in payments to the DOE of as much as $ 160 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 March 31, 2017 , TVA had paid out approximately $ 151 million for this program, and the obligation recorded was $ 9 million .
Reclassifications [Text Block]	Reclassifications Certain historical amounts have been reclassified in the Consolidated Statement of Cash Flows for the six months ended March 31, 2016. Amounts previously presented in Cash flows from operating activities as Insurance recoveries of $7 million for the six months ended March 31, 2016, are currently reported in Other, net.

Variable Interest Entities (Pol

Variable Interest Entities (Policies)	6 Months Ended
	Mar. 31, 2017
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Variable Interest Entity Policy	A VIE is an entity that either (i) has insufficient equity to permit the entity to finance its activities without additional subordinated financial support or (ii) has equity investors who lack the characteristics of owning a controlling financial interest. When TVA determines that it has a variable interest in a variable interest entity, a qualitative evaluation is performed to assess which interest holders have the power to direct the activities that most significantly impact the economic performance of the entity and have the obligation to absorb losses or receive benefits that could be significant to the entity. The evaluation considers the purpose and design of the business, the risks that the business was designed to create and pass along to other entities, the activities of the business that can be directed and which party can direct them, and the expected relative impact of those activities on the economic performance of the business through its life. TVA has the power to direct the activities of an entity when it has the ability to make key operating and financing decisions, including, but not limited to, capital investment and the issuance of debt. Based on the evaluation of these criteria, TVA has determined it is the primary beneficiary of three entities and as such is required to account for the VIEs on a consolidated basis.

Impact of New Accounting Stan25

Impact of New Accounting Standards and Interpretations Impact of New Accounting Standards and Interpretations (Tables)	6 Months Ended
	Mar. 31, 2017
Accounting Changes and Error Corrections [Abstract]
Schedule of New Accounting Pronouncements and Changes in Accounting Principles	The following are accounting standard updates issued by the Financial Accounting Standards Board ("FASB") that TVA adopted during 2017. Consolidation Description This guidance amends the consolidation analysis for VIEs as well as voting interest entities. The standard reduces the number of consolidation models through the elimination of the indefinite deferral for certain entities that was previously allowed and places more emphasis on risk of loss when determining a controlling financial interest. This guidance allows for either a full retrospective or a modified retrospective application. Effective Date for TVA October 1, 2016 Effect on the Financial Statements or Other Significant Matters The adoption of the standard did not materially impact TVA's financial condition, results of operations, or cash flows. The following accounting standards have been issued, but as of March 31, 2017 , were not effective and had not been adopted by TVA. Defined Benefit Costs Description This guidance changes how information about defined benefit costs for pension plans and other post-retirement benefit plans is presented in employer financial statements. The guidance requires employers that present a measure of operating income in their statement of income to include only the service cost component of net periodic pension cost and net periodic postretirement benefit cost in operating expenses (together with other employee compensation costs). The other components of net benefit cost, including amortization of prior service cost/credit, and settlement and curtailment effects, are to be included in nonoperating expenses. Additionally, the guidance stipulates that only the service cost component of net benefit cost is eligible for capitalization in assets. Effective Date for TVA The new standard is effective for TVA’s interim and annual reporting periods beginning October 1, 2018. While early adoption is permitted, TVA does not currently plan to adopt the standard early. Effect on the Financial Statements or Other Significant Matters TVA is currently evaluating the potential impact of these changes on its consolidated financial statements and related disclosures. Revenue Recognition Description In 2014, the FASB issued new guidance related to revenue from contracts with customers. The guidance, including subsequent amendments, replaces the existing accounting standard and industry specific guidance for revenue recognition with a five-step model for recognizing and measuring revenue from contracts with customers. The underlying principle of the guidance is to recognize revenue to depict the transfer of goods or services to customers at the amount expected to be collected. The objective of the new standard is to provide a single, comprehensive revenue recognition model for all contracts with customers to improve comparability within industries and across industries. The new standard also requires enhanced disclosures regarding the nature, amount, timing, and uncertainty of revenue and the related cash flows arising from contracts with customers. At adoption, companies must also select a transition method to be applied either retrospectively to each prior reporting period presented or retrospectively with a cumulative effect adjustment to retained earnings at the date of initial adoption. Effective Date for TVA The new standard is effective for TVA’s interim and annual reporting periods beginning October 1, 2018. While early adoption is permitted, TVA does not currently plan to adopt the standard early. Effect on the Financial Statements or Other Significant Matters While TVA expects most of its revenue to be included in the scope of the new guidance, it has not completed its evaluation of all such arrangements. TVA’s current efforts in evaluating the impact of the standard are focused on scoping of revenue streams and evaluating contracts with local power companies, which represent the majority of TVA's revenues. TVA is also conducting ongoing evaluations of how the new guidance impacts other transactions, including sales to directly served industrial customers, sales to federal agencies, purchase power agreements, contributions in aid of construction, fuel cost adjustments, and other revenue streams. In addition, the power and utilities industry is currently addressing certain industry-specific issues which have not yet been finalized. As the ultimate impact of the new standard has not yet been determined, TVA has not yet elected its transition method. Inventory Valuation Description This guidance changes the model used for the subsequent measurement of inventory from the previous lower of cost or market model to the lower of cost or net realizable value. The guidance applies only to inventory valued using methods other than last-in, first out or the retail inventory method (for example, first-in, first-out or average cost). This amendment is intended to simplify the subsequent measurement of inventory. When the standard becomes effective, it includes interim periods within the fiscal year that begins on that date, and is required to be applied prospectively. Effective Date for TVA The new standard is effective for TVA’s interim and annual reporting periods beginning October 1, 2017. While early adoption is permitted, TVA does not currently plan to adopt the standard early. Effect on the Financial Statements or Other Significant Matters TVA does not expect the adoption of this standard to have a material impact on TVA's financial condition, results of operations, or cash flows. Lease Accounting Description This guidance changes the provisions of recognition in both the lessee and lessor accounting models. The standard requires entities that lease assets — referred to as "lessees" — to recognize on the balance sheet the assets and liabilities for the rights and obligations created by leases with terms of more than 12 months. The recognition, measurement, and presentation of expenses and cash flows arising from a lease by a lessee primarily will depend on its classification as a finance (similar to current capital leases) or operating lease. However, unlike current lease accounting rules — which require only capital leases to be recognized on the balance sheet — the new standard will require both types of leases to be recognized on the balance sheet. Operating leases will result in straight-line expense, while finance leases will result in recognition of interest on the lease liability separate from amortization expense. The accounting for the owner of the assets leased by the lessee — also known as lessor accounting — will remain largely unchanged from current lease accounting rules. When the standard becomes effective, it will include interim periods within that fiscal year, and will be required to be applied using a modified retrospective transition. Effective Date for TVA The new standard is effective for TVA’s interim and annual reporting periods beginning October 1, 2019. While early adoption is permitted, TVA does not currently plan to adopt the standard early. Effect on the Financial Statements or Other Significant Matters TVA is currently evaluating the potential impact of these changes on its consolidated financial statements and related disclosures. Financial Instruments Description This guidance applies to the recognition and measurement of financial assets and liabilities. The standard requires all equity investments to be measured at fair value with changes in the fair value recognized through net income (other than those accounted for under the equity method of accounting or those that result in consolidation of the investee). The standard also amends presentation requirements related to certain changes in the fair value of a liability and eliminates certain disclosure requirements of significant assumptions for financial instruments measured at amortized cost on the balance sheet. Public entities must apply the amendments by means of a cumulative-effect adjustment to the balance sheet as of the beginning of the fiscal year of adoption. Effective Date for TVA The new standard is effective for TVA’s interim and annual reporting periods beginning October 1, 2018. Early adoption is not permitted unless specific early adoption guidance is applied. TVA does not currently plan to adopt the standard early. Effect on the Financial Statements or Other Significant Matters TVA currently measures all of its equity investments (other than those that result in the consolidation of the investee) at fair value, with changes in the fair value recognized through net income. If TVA’s Board has authorized the use of regulatory accounting, the changes in fair value are deferred as regulatory assets or liabilities. TVA currently discloses significant assumptions around its estimates of fair value for financial instruments carried at amortized cost on its consolidated balance sheet. TVA is currently evaluating the potential impact of the changes in this new guidance on its consolidated financial statements and related disclosures. Derivatives and Hedging Description This guidance clarifies the requirements for assessing whether contingent call or put options that can accelerate the payment of principal on debt instruments are clearly and closely related to their debt hosts. An entity performing the assessment under the amendments in this update is required to assess the embedded call or put options solely in accordance with a four-step decision sequence. When the standard becomes effective, it will include interim periods within that fiscal year, and will be required to be applied using a modified retrospective transition. Effective Date for TVA The new standard is effective for TVA’s interim and annual reporting periods beginning October 1, 2017. While early adoption is permitted, TVA does not currently plan to adopt the standard early. Effect on the Financial Statements or Other Significant Matters TVA has two issues of Putable Automatic Rate Reset Securities (“PARRS”) outstanding. After a fixed-rate period of five years, the coupon rate on the PAARS may automatically be reset downward under certain market conditions on an annual basis. The coupon rate reset on the PARRS is based on a calculation. If the coupon rate is going to be reset, holders may request, for a limited period of time, redemption of the Bonds at par value, with repayment of principal on the reset date. This put option is otherwise not available. For both series of PARRS, the coupon rate will reset downward on the reset date if the rate calculated is below the then-current coupon rate on the Bond. TVA plans to assess whether these contingent put options, that can accelerate the payment of principal on the PARRS, continue to be clearly and closely related to their debt hosts under the new guidance. TVA plans to assess the put options in accordance with the four-step decision sequence clarified in the guidance. While a preliminary assessment indicates that TVA does not believe the new guidance will impact its current assessment, TVA will continue to evaluate the potential impact of the new guidance on its consolidated balance sheet.

Accounts Receivable, Net (Table

Accounts Receivable, Net (Tables)	6 Months Ended
	Mar. 31, 2017
Accounts Receivable, Net [Abstract]
Accounts Receivable, Net	The table below summarizes the types and amounts of TVA’s accounts receivable: Accounts Receivable, Net At March 31, 2017 At September 30, 2016 Power receivables $ 1,233 $ 1,637 Other receivables 78 111 Allowance for uncollectible accounts (1 ) (1 ) Accounts receivable, net $ 1,310 $ 1,747

Inventories, Net (Tables)

Inventories, Net (Tables)	6 Months Ended
	Mar. 31, 2017
Inventory, Net [Abstract]
Inventories, Net	The table below summarizes the types and amounts of TVA’s inventories: Inventories, Net At March 31, 2017 At September 30, 2016 Materials and supplies inventory $ 745 $ 673 Fuel inventory 418 345 Emission allowance inventory, net 16 14 Allowance for inventory obsolescence (31 ) (39 ) Inventories, net $ 1,148 $ 993

Other Long-Term Assets (Tables)

Other Long-Term Assets (Tables)	6 Months Ended
	Mar. 31, 2017
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 March 31, 2017 At September 30, 2016 Loans and other long-term receivables, net $ 157 $ 136 EnergyRight ® receivables 108 112 Prepaid capacity payments 38 42 Commodity contract derivative assets — 3 Other 77 93 Other long-term assets $ 380 $ 386

Regulatory Assets and Liabili29

Regulatory Assets and Liabilities (Tables)	6 Months Ended
	Mar. 31, 2017
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 March 31, 2017 At September 30, 2016 Current regulatory assets Deferred nuclear generating units $ 237 $ 237 Unrealized losses on commodity derivatives 109 122 Fuel cost adjustment receivable — 98 Environmental agreements 17 34 Environmental cleanup costs - Kingston ash spill 43 42 Other current regulatory assets 2 3 Total current regulatory assets 408 536 Non-current regulatory assets Deferred pension costs and other post-retirement benefits costs 5,270 5,385 Unrealized losses on interest rate derivatives 1,088 1,547 Nuclear decommissioning costs 882 938 Deferred nuclear generating units 871 850 Non-nuclear decommissioning costs 822 819 Environmental cleanup costs - Kingston ash spill 283 299 Unrealized losses on commodity derivatives 33 56 Environmental agreements 14 18 Other non-current regulatory assets 232 252 Total non-current regulatory assets 9,495 10,164 Total regulatory assets $ 9,903 $ 10,700 Current regulatory liabilities Fuel cost adjustment tax equivalents $ 150 $ 148 Fuel cost adjustment payable 8 — Unrealized gains on commodity derivatives 25 6 Total current regulatory liabilities 183 154 Non-current regulatory liabilities Unrealized gains on commodity derivatives — 3 Total regulatory liabilities $ 183 $ 157

Variable Interest Entities (Tab

Variable Interest Entities (Tables)	6 Months Ended
	Mar. 31, 2017
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 March 31, 2017 , and September 30, 2016 , as reflected in the consolidated balance sheets are as follows: Summary of Impact of VIEs on Consolidated Balance Sheets At March 31, 2017 At September 30, 2016 Current liabilities Accrued interest $ 11 $ 11 Accounts payable and accrued liabilities 2 2 Current maturities of long-term debt of variable interest entities 35 35 Total current liabilities 48 48 Other liabilities Other long-term liabilities 31 33 Long-term debt, net Long-term debt of variable interest entities, net 1,182 1,199 Total liabilities $ 1,261 $ 1,280

Other Long-Term Liabilities (Ta

Other Long-Term Liabilities (Tables)	6 Months Ended
	Mar. 31, 2017
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 March 31, 2017 At September 30, 2016 Interest rate swap liabilities $ 1,479 $ 1,938 Capital lease obligations 179 177 Currency swap liabilities 145 162 EnergyRight ® financing obligation 125 130 Membership interests of VIE subject to mandatory redemption 31 33 Commodity contract derivative liabilities 33 49 Environmental agreements liability 14 18 Other 312 269 Total other long-term liabilities $ 2,318 $ 2,776

Asset Retirement Obligations (T

Asset Retirement Obligations (Tables)	6 Months Ended
	Mar. 31, 2017
Asset Retirement Obligation Disclosure [Abstract]
Asset Retirement Obligation Activity	Asset Retirement Obligation Activity Nuclear Non-Nuclear Total Balance at September 30, 2016 $ 2,492 $ 1,560 $ 4,052 Settlements — (58 ) (58 ) Revisions in estimate — 46 46 Additional obligations — 1 1 Accretion (recorded as regulatory asset) 58 16 74 Balance at March 31, 2017 $ 2,550 $ 1,565 $ 4,115 (1 ) Note (1) The current portion of ARO in the amount of $ 200 million and $ 212 million is included in Accounts payable and accrued liabilities at March 31, 2017 , and September 30, 2016 , respectively.

Debt and Other Obligations (Tab

Debt and Other Obligations (Tables)	6 Months Ended
	Mar. 31, 2017
Debt Disclosure [Abstract]
Debt Outstanding	Total debt outstanding at March 31, 2017 , and September 30, 2016 , consisted of the following: Debt Outstanding At March 31, 2017 At September 30, 2016 Short-term debt Short-term debt, net $ 815 $ 1,407 Current maturities of power bonds 1,681 1,555 Current maturities of long-term debt of variable interest entities 35 35 Current maturities of notes payable 28 27 Total current debt outstanding, net 2,559 3,024 Long-term debt Long-term power bonds (1) 21,384 21,063 Long-term debt of variable interest entities 1,193 1,211 Long-term notes payable 21 48 Unamortized discounts, premiums, issue costs, and other (170 ) (174 ) Total long-term debt, net 22,428 22,148 Total outstanding debt $ 24,987 $ 25,172 Note (1) Includes net exchange gain from currency transactions of $ 176 million at March 31, 2017 , and $ 150 million at September 30, 2016 .
Debt Securities Activity	The table below summarizes the long-term debt securities activity for the period from October 1, 2016, to March 31, 2017 : Debt Securities Activity Date Amount (1) Interest Rate Issues 2017 Series A (2) February 2017 $ 1,000 2.88 % Discount on debt issues (1 ) Total long-term debt issuances $ 999 Redemptions/Maturities electronotes ® First Quarter 2017 $ 1 2.65 % electronotes ® Second Quarter 2017 1 3.29 % 2009 Series B December 2016 1 3.77 % 2001 Series D December 2016 525 4.88 % Total redemptions/maturities of power bonds 528 Notes payable 26 0.81 % Debt of variable interest entities 17 4.30 % Total redemptions/maturities of debt $ 571 Note (1) All redemptions were at 100 percent of par. (2) The 2017 Series A bonds were issued at 99.9 percent of par.
Credit Facility Agreements
Summary of Long-Term Credit Facilities	The following table provides additional information regarding TVA's funding available under the four long-term credit facilities: Summary of Long-Term Credit Facilities At March 31, 2017 Maturity Date Facility Limit Letters of Credit Outstanding Cash Borrowings Availability December 2019 $ 150 $ 38 $ — $ 112 February 2021 500 500 — — June 2020 1,000 278 — 722 September 2020 1,000 288 — 712 Total $ 2,650 $ 1,104 $ — $ 1,546

Risk Management Activities an34

Risk Management Activities and Derivative Transactions (Tables)	6 Months Ended
	Mar. 31, 2017
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 Six Months Ended Derivatives in Cash Flow Hedging Relationship Objective of Hedge Transaction Accounting for Derivative Hedging Instrument 2017 2016 2017 2016 Currency swaps To protect against changes in cash flows caused by changes in foreign currency exchange rates (exchange rate risk) Unrealized gains and losses are recorded in AOCI and reclassified to interest expense to the extent they are offset by gains and losses on the hedged transaction. $ 25 $ (27 ) $ 17 $ (54 ) Summary of Derivative Instruments That Receive Hedge Accounting Treatment (part 2) (1) Amount of Gain (Loss) Reclassified from OCI to Interest Expense Three Months Ended Six Months Ended Derivatives in Cash Flow Hedging Relationship 2017 2016 2017 2016 Currency swaps $ 12 $ (22 ) $ (26 ) $ (46 ) Note (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 $ 15 million of gains from AOCI to interest expense within the next twelve months to offset amounts anticipated to be recorded in interest expense related to net 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 March 31 ( 1) Six Months Ended March 31 (1) Derivative Type Objective of Derivative Accounting for Derivative Instrument 2017 2016 2017 2016 Interest rate swaps To fix short-term debt variable rate to a fixed rate (interest rate risk) Mark-to-market gains and losses are recorded as regulatory assets or liabilities. Realized gains and losses are recognized in interest expense when payments are made or received on the swap settlement dates. $ (26 ) $ (27 ) $ (52 ) $ (55 ) 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. 2 — — — Commodity derivatives under 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. (6 ) (21 ) (21 ) (56 ) Note (1) All of TVA's derivative instruments that do not receive hedge accounting treatment have unrealized gains (losses) that would otherwise be recognized in income but instead are deferred as regulatory assets and liabilities. As such, there was no related gain (loss) recognized in income for these unrealized gains (losses) for the three months and six months ended March 31, 2017 and 2016 .
Fair Value of TVA Derivatives	Fair Values of TVA Derivatives At March 31, 2017 At September 30, 2016 Derivatives That Receive Hedge Accounting Treatment Balance Balance Sheet Presentation Balance Balance Sheet Presentation Currency swaps £200 million Sterling $ (84 ) Other long-term liabilities $ (82 ) Other long-term liabilities £250 million Sterling (34 ) Other long-term liabilities (41 ) Other long-term liabilities £150 million Sterling (27 ) Other long-term liabilities (39 ) Other long-term liabilities At March 31, 2017 At September 30, 2016 Derivatives That Do Not Receive Hedge Accounting Treatment Balance Balance Sheet Presentation Balance Balance Sheet Presentation Interest rate swaps $1.0 billion notional (1,072 ) Other long-term liabilities (1,387 ) Other long-term liabilities $476 million notional (398 ) Other long-term liabilities (539 ) Other long-term liabilities $42 million notional (9 ) Other long-term liabilities (12 ) Other long-term liabilities Commodity contract derivatives (97 ) Other current assets $25; Other long-term liabilities $(33); Accounts payable and accrued liabilities $(89) (125 ) Other current assets $6; Other long-term assets $3; Other long-term liabilities $(49); Accounts payable and accrued liabilities $(85) FTP Derivatives under FTP (1) (17 ) Other current assets $(13); Accounts payable and accrued liabilities $(4) (39 ) Other current assets $(30); Other long-term liabilities $(2); Accounts payable and accrued liabilities $(7) Note (1) Fair values of certain derivatives under the FTP that were in net liability positions totaling $13 million and $30 million at March 31, 2017 , and September 30, 2016 , 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.
Commodity Contract Derivatives	Commodity Contract Derivatives At March 31, 2017 At September 30, 2016 Number of Contracts Notional Amount Fair Value (MtM) Number of Contracts Notional Amount Fair Value ( MtM ) Coal contract derivatives 19 21 million tons $ (113 ) 20 20 million tons $ (127 ) Natural gas contract derivatives 48 278 million mmBtu $ 16 39 148 million mmBtu $ 2
Derivatives Under Financial Trading Program	Derivatives Under Financial Trading Program (1) At March 31, 2017 At September 30, 2016 Notional Amount Fair Value (MtM) (in millions) Notional Amount Fair Value (MtM) (in millions) Natural gas (in mmBtu) Swap contracts 11,200,000 $ (17 ) 21,052,500 $ (39 ) Note (1) Fair value amounts presented are based on the net commodity position with the counterparty. Notional amounts disclosed represent the net value of contractual amounts.
Financial Trading Program Unrealized Gains (Losses)	TVA experienced the following unrealized and realized gains and losses related to the FTP at the dates and during the periods, as applicable, set forth in the tables below: Financial Trading Program Unrealized Gains (Losses) At March 31 2017 At September 30 2016 FTP unrealized gains (losses) deferred as regulatory liabilities (assets) Natural gas $ (17 ) $ (39 )
Financial Trading Program Realized Gains (Losses)	Financial Trading Program Realized Gains (Losses) Three Months Ended Six Months Ended 2017 2016 2017 2016 Decrease (increase) in fuel expense Natural gas $ (5 ) $ (17 ) $ (17 ) $ (45 ) Financial Trading Program Realized Gains (Losses) Three Months Ended Six Months Ended 2017 2016 2017 2016 Decrease (increase) in purchased power expense Natural gas $ (1 ) $ (4 ) $ (4 ) $ (11 )
Derivative Assets and Liabilities	The amounts of TVA's derivative instruments as reported in the consolidated balance sheets as of March 31, 2017 , and September 30, 2016 , are shown in the table below: Derivative Assets and Liabilities As of March 31, 2017 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 Commodity derivatives not subject to master netting or similar arrangement $ 25 $ — $ 25 Liabilities Currency swap(s) (3) $ 145 $ — $ 145 Interest rate swaps (3) 1,479 — 1,479 Commodity derivatives under FTP 17 (13 ) 4 Total derivatives subject to master netting or similar arrangement 1,641 (13 ) 1,628 Commodity derivatives not subject to master netting or similar arrangement 122 — 122 Total liabilities $ 1,763 $ (13 ) $ 1,750 As of September 30, 2016 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 Commodity derivatives under FTP subject to master netting or similar arrangement $ 6 $ (6 ) $ — Commodity derivatives not subject to master netting or similar arrangement 9 — 9 Total $ 15 $ (6 ) $ 9 Liabilities Currency swap(s) (3) $ 162 $ — $ 162 Interest rate swaps (3) 1,938 — 1,938 Commodity derivatives under FTP 45 (36 ) 9 Total derivatives subject to master netting or similar arrangement 2,145 (36 ) 2,109 Commodity derivatives not subject to master netting or similar arrangement 134 — 134 Total $ 2,279 $ (36 ) $ 2,243 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 that are not offset in the consolidated balance sheets. (3) Letters of credit of approximately $ 1.1 billion and $ 1.4 billion were posted as collateral at March 31, 2017 , and September 30, 2016 , 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.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	6 Months Ended
	Mar. 31, 2017
Fair Value Disclosures [Abstract]
Valuation Techniques	The measurement of fair value results in classification into a hierarchy by the inputs used to determine the fair value as follows: Level 1 — Unadjusted quoted prices in active markets accessible by the reporting entity for identical assets or liabilities. Active markets are those in which transactions for the asset or liability occur with sufficient frequency and volume to provide pricing. Level 2 — Pricing inputs other than quoted market prices included in Level 1 that are based on observable market data and that are directly or indirectly observable for substantially the full term of the asset or liability. These include quoted market prices for similar assets or liabilities, quoted market prices for identical or similar assets in markets that are not active, adjusted quoted market prices, inputs from observable data such as interest rate and yield curves, volatilities and default rates observable at commonly quoted intervals, and inputs derived from observable market data by correlation or other means. Level 3 — Pricing inputs that are unobservable, or less observable, from objective sources. Unobservable inputs are only to be used to the extent observable inputs are not available. These inputs maintain the concept of an exit price from the perspective of a market participant and should reflect assumptions of other market participants. An entity should consider all market participant assumptions that are available without unreasonable cost and effort. These are given the lowest priority and are generally used in internally developed methodologies to generate management's best estimate of the fair value when no observable market data is available.
Unrealized Investment Gains (Losses)	TVA recorded unrealized gains and losses related to its trading securities held during each period as follows: Unrealized Investment Gains (Losses) Three Months Ended Six Months Ended Fund Financial Statement Presentation 2017 2016 2017 2016 SERP Other income (expense) $ 2 $ — $ 1 $ — LTDCP Other income (expense) 1 — — — NDT Regulatory asset 42 9 35 48 ART Regulatory asset 19 (3 ) 22 9
Fair Value Measurements	Fair Value Measurements At March 31, 2017 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 $ 205 $ — $ — $ 205 Government debt securities 76 58 — 134 Corporate debt securities — 408 — 408 Mortgage and asset-backed securities — 46 — 46 Institutional mutual funds 83 — — 83 Forward debt securities contracts — 10 — 10 Private equity funds measured at net asset value (1) — — — 139 Private real estate funds measured at net asset value (1) — — — 112 Commingled funds measured at net asset value (1) — — — 1,251 Total investments 364 522 — 2,388 Commodity contract derivatives — 22 3 25 Total $ 364 $ 544 $ 3 $ 2,413 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) $ — $ 145 $ — $ 145 Interest rate swaps — 1,479 — 1,479 Commodity contract derivatives — 6 116 122 Commodity derivatives under FTP (2) Swap contracts — 4 — 4 Total $ — $ 1,634 $ 116 $ 1,750 Notes (1) Certain investments that are measured at fair value using the net asset value per share (or its equivalent) practical expedient have not been categorized in the fair value hierarchy. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the amounts presented in the consolidated balance sheets. (2) Due to the right of setoff and method of settlement, TVA elects to record commodity derivatives under the FTP based on its net commodity position with the counterparty or FCM. Deposits are made to TVA's margin cash accounts held with each FCM to offset any net liability positions in full for derivatives that are transacted with FCMs. TVA records currency swaps net of cash collateral received from or paid to the counterparty, to the extent such amount is not recorded in Accounts payable and accrued liabilities. See Note 12 — Offsetting of Derivative Assets and Liabilities . Fair Value Measurements At September 30, 2016 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 $ 196 $ — $ — $ 196 Government debt securities 88 36 — 124 Corporate debt securities — 393 — 393 Mortgage and asset-backed securities — 50 — 50 Institutional mutual funds 92 — — 92 Forward debt securities contracts — 15 — 15 Private equity funds measured at net asset value (1) — — — 132 Private real estate funds measured at net asset value (1) — — — 113 Commingled funds measured at net asset value (1) — — — 1,142 Total investments 376 494 — 2,257 Commodity contract derivatives — 5 4 9 Total $ 376 $ 499 $ 4 $ 2,266 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) $ — $ 162 $ — $ 162 Interest rate swaps — 1,938 — 1,938 Commodity contract derivatives — 3 131 134 Commodity derivatives under FTP (2) Swap contracts — 9 — 9 Total $ — $ 2,112 $ 131 $ 2,243 Notes (1) Certain investments that are measured at fair value using the net asset value per share (or its equivalent) practical expedient have not been categorized in the fair value hierarchy. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the amounts presented in the consolidated balance sheets. (2) Due to the right of setoff and method of settlement, TVA elects to record commodity derivatives under the FTP based on its net commodity position with the counterparty or FCM. Deposits are made to TVA's margin cash accounts held with each FCM to offset any net liability positions in full for derivatives that are transacted with FCMs. TVA records currency swaps net of cash collateral received from or paid to the counterparty, to the extent such amount is not recorded in Accounts payable and accrued liabilities. See Note 12 — Offsetting of Derivative Assets and Liabilities .
Fair Value Measurements Using Significant Unobservable Inputs	The following table presents a reconciliation of all commodity contract derivatives measured at fair value on a recurring basis using significant unobservable inputs (Level 3): Fair Value Measurements Using Significant Unobservable Inputs Commodity Contract Derivatives Three Months Ended Six Months Ended Balance at beginning of period $ (123 ) $ (98 ) Net unrealized gains (losses) deferred as regulatory assets and liabilities (64 ) (89 ) Balance at March 31, 2016 $ (187 ) $ (187 ) Balance at beginning of period $ (104 ) $ (127 ) Net unrealized gains (losses) deferred as regulatory assets and liabilities (8 ) 15 Balance at March 31, 2017 $ (112 ) $ (112 )
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 March 31 2017 Valuation Technique(s) Unobservable Inputs Range Assets Commodity contract derivatives $ 3 Pricing model Coal supply and demand 0.6 - 0.8 billion tons/year Long-term market prices $11.45 - $109.55/ton Liabilities Commodity contract derivatives $ 116 Pricing model Coal supply and demand 0.6 - 0.8 billion tons/year Long-term market prices $11.45 - $109.55/ton Quantitative Information about Level 3 Fair Value Measurements Fair Value at September 30 2016 Valuation Technique(s) Unobservable Inputs Range Assets Commodity contract derivatives $ 4 Pricing model Coal supply and demand 0.7 - 0.8 billion tons/year Long-term market prices $11.80 - $85.02/ton Liabilities Commodity contract derivatives $ 131 Pricing model Coal supply and demand 0.7 - 0.8 billion tons/year Long-term market prices $11.80 - $85.02/ton
Estimated Values of Financial Instruments Not Recorded at Fair Value	The estimated values of TVA's financial instruments not recorded at fair value at March 31, 2017 , and September 30, 2016 , were as follows: Estimated Values of Financial Instruments Not Recorded at Fair Value At March 31, 2017 At September 30, 2016 Valuation Classification Carrying Amount Fair Value Carrying Amount Fair Value EnergyRight ® receivables (including current portion) Level 2 $ 135 $ 138 $ 141 $ 144 Loans and other long-term receivables, net (including current portion) Level 2 $ 161 $ 150 $ 141 $ 130 EnergyRight ® financing obligation (including current portion) Level 2 $ 156 $ 175 $ 163 $ 183 Unfunded loan commitments Level 2 $ — $ 14 $ — $ 17 Membership interest of variable interest entity subject to mandatory redemption (including current portion) Level 2 $ 33 $ 42 $ 35 $ 46 Long-term outstanding power bonds (including current maturities), net Level 2 $ 22,906 $ 26,983 $ 22,456 $ 28,620 Long-term debt of variable interest entities (including current maturities), net Level 2 $ 1,217 $ 1,353 $ 1,234 $ 1,468 Long-term notes payable (including current maturities) Level 2 $ 49 $ 49 $ 75 $ 75

Other Income (Expense), Net (Ta

Other Income (Expense), Net (Tables)	6 Months Ended
	Mar. 31, 2017
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 Three Months Ended Six Months Ended 2017 2016 2017 2016 External services $ 5 $ 3 $ 8 $ 7 Interest income 6 6 11 12 Gains (losses) on investments 4 — 4 3 Miscellaneous — (1 ) 4 (2 ) Total other income (expense), net $ 15 $ 8 $ 27 $ 20

Benefit Plans (Tables)

Benefit Plans (Tables)	6 Months Ended
	Mar. 31, 2017
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 six months ended March 31, 2017 and 2016 , were as follows: Components of TVA’s Benefit Plans For the Three Months Ended March 31 For the Six Months Ended March 31 Pension Benefits Other Post-Retirement Benefits Pension Benefits Other Post-Retirement Benefits 2017 2016 2017 2016 2017 2016 2017 2016 Service cost $ 13 $ 34 $ 5 $ 4 $ 30 $ 66 $ 9 $ 8 Interest cost 116 142 4 8 232 282 11 15 Expected return on plan assets (114 ) (112 ) — — (228 ) (223 ) — — Amortization of prior service credit (24 ) (5 ) (10 ) (2 ) (49 ) (11 ) (11 ) (3 ) Recognized net actuarial loss 120 82 5 1 236 155 7 3 Total net periodic benefit cost as actuarially determined 111 141 4 11 221 269 16 23 Amount capitalized due to actions of regulator (34 ) (71 ) — — (68 ) (129 ) — — Total net periodic benefit cost $ 77 $ 70 $ 4 $ 11 $ 153 $ 140 $ 16 $ 23

Summary of Significant Accoun38

Summary of Significant Accounting Policies General and Basis of Presentation (Details) People in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2017USD ($)variable_interest_entities	Mar. 31, 2016USD ($)	Mar. 31, 2017USD ($)variable_interest_entities	Mar. 31, 2016USD ($)	Mar. 31, 2017	Mar. 31, 2017People	Mar. 31, 2017USD ($)	Mar. 31, 2017Sites	Sep. 30, 2016USD ($)
General and Basis of Presentation
Population of TVA's service area | People						9
Number of wholly-owned direct subsidiaries					2
Number of variable interest entities | variable_interest_entities	3		3
Reclassification from Insurance Recoveries to Other, net			$ 7
Allowance for uncollectible accounts, accounts receivable							$ 1		$ 1
Loans receivable, carrying value							150		130
Allowance for loans receivable							8		$ 8
Revenue capitalized during pre-commercial operations	$ 6		20
Number of construction projects					2			1
Fuel cost capitalized during pre-commercial operations	8		13
Depreciation expense	$ 336	$ 369	$ 672	$ 733
Change in depreciation due to new study	56		112
AFUDC minimum total project cost			$ 1,000
AFUDC capitalized		$ 58		$ 116
Total estimated amount of BLEU payments							160
Payments attributable to BLEU fuel program							151
BLEU fuel obligation							$ 9

Accounts Receivable, Net (Detai

Accounts Receivable, Net (Details) - USD ($) $ in Millions	Mar. 31, 2017	Sep. 30, 2016
Accounts Receivable, Net
Power receivables	$ 1,233	$ 1,637
Other receivables	78	111
Allowance for uncollectible accounts	(1)	(1)
Accounts receivable, net	$ 1,310	$ 1,747

Inventories, Net (Details)

Inventories, Net (Details) - USD ($) $ in Millions	Mar. 31, 2017	Sep. 30, 2016
Inventories, Net
Materials and supplies inventory	$ 745	$ 673
Fuel inventory	418	345
Emission allowance inventory, net	16	14
Allowance for inventory obsolescence	(31)	(39)
Inventories, net	$ 1,148	$ 993

Other Long-Term Assets (Details

Other Long-Term Assets (Details) - USD ($) $ in Millions	6 Months Ended
	Mar. 31, 2017	Sep. 30, 2016
Other Long-Term Assets
EnergyRight® receivables	$ 138	$ 144
Other long-term assets	380	386
Other long-term assets
Other Long-Term Assets
Loans and other long-term receivables, net	157	136
EnergyRight® receivables	108	112
Prepaid capacity payments	38	42
Commodity contract derivative assets	0	3
Other	77	93
Accounts Receivable
Other Long-Term Assets
EnergyRight® receivables	$ 27	$ 29
Energy Right
Other Long-Term Assets
Number of days in default	180 days
Energy Right | Minimum
Other Long-Term Assets
EnergyRight loan term	5 years
Energy Right | Maximum
Other Long-Term Assets
EnergyRight loan term	10 years

Regulatory Assets and Liabili42

Regulatory Assets and Liabilities (Details) - USD ($)	6 Months Ended
	Mar. 31, 2017	Nov. 14, 2016	Sep. 30, 2016
Regulatory Assets and Liabilities
Current regulatory assets	$ 408,000,000		$ 536,000,000
Non-current regulatory assets	9,495,000,000		10,164,000,000
Regulatory assets	9,903,000,000		10,700,000,000
Current regulatory liabilities	183,000,000		154,000,000
Non-current regulatory liabilities	0		3,000,000
Regulatory liabilities	183,000,000		157,000,000
Bellefonte site contract to sell		$ 111
Net book value and related ARO's of Bellefonte assets	121,000,000
Amount received on Bellefonte contract to sell	22,000,000
Amount to receive on Bellefonte contract to sell at closing	$ 89,000,000
Max number of years buyer had to close	2 years
Yearly amortization of Deferred nuclear generating units	$ 237,000,000
Fuel cost adjustment tax equivalents
Regulatory Assets and Liabilities
Current regulatory liabilities	150,000,000		148,000,000
Fuel cost adjustment receivable/liability
Regulatory Assets and Liabilities
Current regulatory liabilities	8,000,000		0
Unrealized losses on commodity derivatives
Regulatory Assets and Liabilities
Current regulatory liabilities	25,000,000		6,000,000
Deferred nuclear generating units
Regulatory Assets and Liabilities
Current regulatory assets	237,000,000		237,000,000
Non-current regulatory assets	871,000,000		850,000,000
Unrealized losses on commodity derivatives
Regulatory Assets and Liabilities
Current regulatory assets	109,000,000		122,000,000
Non-current regulatory assets	33,000,000		56,000,000
Fuel cost adjustment receivable/liability
Regulatory Assets and Liabilities
Current regulatory assets	0		98,000,000
Environmental agreements
Regulatory Assets and Liabilities
Current regulatory assets	17,000,000		34,000,000
Non-current regulatory assets	14,000,000		18,000,000
Environmental cleanup costs - Kingston ash spill
Regulatory Assets and Liabilities
Current regulatory assets	43,000,000		42,000,000
Non-current regulatory assets	283,000,000		299,000,000
Other current regulatory assets
Regulatory Assets and Liabilities
Current regulatory assets	2,000,000		3,000,000
Deferred pension costs and other post-retirement benefits costs
Regulatory Assets and Liabilities
Non-current regulatory assets	5,270,000,000		5,385,000,000
Unrealized losses on interest rate derivatives
Regulatory Assets and Liabilities
Non-current regulatory assets	1,088,000,000		1,547,000,000
Nuclear decommissioning costs
Regulatory Assets and Liabilities
Non-current regulatory assets	882,000,000		938,000,000
Non-nuclear decommissioning costs
Regulatory Assets and Liabilities
Non-current regulatory assets	822,000,000		819,000,000
Other non-current regulatory assets
Regulatory Assets and Liabilities
Non-current regulatory assets	$ 232,000,000		$ 252,000,000

Variable Interest Entities Vari

Variable Interest Entities Variable Interest Entities (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Dec. 31, 2016	Mar. 31, 2016	Mar. 31, 2017	Mar. 31, 2016	Sep. 30, 2016	Sep. 30, 2013	Sep. 30, 2012
Variable Interest Entities
Accrued interest			$ 11		$ 11
Interest Expense	$ 15	$ 15	30	$ 31
VIE Financing
Construction management agreement and lease			1,261		1,280		$ 1,000
Face amount						$ 40
Financial instruments subject to mandatory redemption, interest rate, stated percentage						7.00%
Liabilities
Current maturities of long-term debt of variable interest entities			35		35
Long-term debt of variable interest entities, net			1,182		1,199
SCCG
VIE Financing
Face amount						$ 360
JSCCG
VIE Financing
Face amount							900
Holdco
VIE Financing
Face amount							$ 100
Accounts payable and accrued liabilities
VIE Financing
Construction management agreement and lease			2		2
Total current liabilities
VIE Financing
Construction management agreement and lease			48		48
Other long-term liabilities
VIE Financing
Construction management agreement and lease			$ 31		$ 33

Other Long-Term Liabilities (De

Other Long-Term Liabilities (Details) - USD ($) $ in Millions		Mar. 31, 2017	Sep. 30, 2016
Other Long-Term Liabilities
Interest rate swap liabilities		$ 1,479	$ 1,938
Capital lease obligations		371	409
Currency swap liabilities	[1]	145	162
EnergyRight® financing obligation		175	183
Total other long-term liabilities		2,318	2,776
Other long-term liabilities
Other Long-Term Liabilities
Interest rate swap liabilities		1,479	1,938
Capital lease obligations		179	177
Currency swap liabilities		145	162
EnergyRight® financing obligation		125	130
Membership interests of VIE subject to mandatory redemption		31	33
Commodity contract derivative liabilities		33	49
Environmental agreements liability		14	18
Other		312	269
Accounts payable and accrued liabilities
Other Long-Term Liabilities
EnergyRight® financing obligation		$ 31	$ 33
[1]	Due to the right of setoff and method of settlement, TVA elects to record commodity derivatives under the FTP based on its net commodity position with the counterparty or FCM. Deposits are made to TVA's margin cash accounts held with each FCM to offset any net liability positions in full for derivatives that are transacted with FCMs. TVA records currency swaps net of cash collateral received from or paid to the counterparty, to the extent such amount is not recorded in Accounts payable and accrued liabilities. See Note 12 — Offsetting of Derivative Assets and Liabilities.

Asset Retirement Obligations (D

Asset Retirement Obligations (Details) - USD ($) $ in Millions		6 Months Ended
		Mar. 31, 2017	Sep. 30, 2016
Asset Retirement Obligations
Asset retirement obligations, period increase		$ 63
Amortization expense of related regulatory assets		72
Balance at September 30, 2016		4,052
Settlements		(58)
Revisions in Estimate		46
Additional obligations		1
Accretion (recorded as regulatory asset)		74
Balance at March 31, 2017	[1]	4,115
Nuclear
Asset Retirement Obligations
Balance at September 30, 2016		2,492
Settlements		0
Revisions in Estimate		0
Additional obligations		0
Accretion (recorded as regulatory asset)		58
Balance at March 31, 2017		2,550
Non-nuclear
Asset Retirement Obligations
Balance at September 30, 2016		1,560
Settlements		(58)
Revisions in Estimate		46
Additional obligations		1
Accretion (recorded as regulatory asset)		16
Balance at March 31, 2017		1,565
Accounts payable and accrued liabilities
Asset Retirement Obligations
Current portion of ARO		$ 200	$ 212
[1]	The current portion of ARO in the amount of $200 million and $212 million is included in Accounts payable and accrued liabilities at March 31, 2017, and September 30, 2016, respectively.

Debt and Other Obligations Debt

Debt and Other Obligations Debt Outstanding (Details) - USD ($) $ in Millions		6 Months Ended
		Mar. 31, 2017	Mar. 31, 2016	Sep. 30, 2016
Short-term debt
Short-term debt, net		$ 815		$ 1,407
Current maturities of power bonds		1,681		1,555
Current maturities of long-term debt of variable interest entities		35		35
Current maturities of notes payable		28		27
Total current debt outstanding, net		2,559		3,024
Long-term debt
Long-term power bonds	[1]	21,384		21,063
Long-term debt of variable interest entities		1,193		1,211
Long-term notes payable		21		48
Unamortized discounts, premiums, issues costs, and other		(170)		(174)
Total long-term debt, net		22,428		22,148
Total outstanding debt		24,987		$ 25,172
Net exchange gain from currency transactions		$ 176	$ 150
[1]	Includes net exchange gain from currency transactions of $176 million at March 31, 2017, and $150 million at September 30, 2016.

Debt and Other Obligations De47

Debt and Other Obligations Debt Securities Activity (Details) - USD ($) $ in Millions		6 Months Ended
		Mar. 31, 2017		Mar. 31, 2016	Dec. 31, 2016
Debt Instrument
Issues of power bonds		$ 999		$ 0
Redemptions/maturities of power bonds		528	[1]	6
Total redemptions/maturities of debt	[1]	571
Repayments of Notes Payable		26		0
Repayments of Other Long-term Debt		$ 17		$ 16
2017 Series A
Debt Instrument
Interest rate		2.88%
Percent of par value		99.90%
electronotes
Debt Instrument
Redemptions/maturities of power bonds		$ 1
Interest rate		3.29%			2.65%
2009 Series B
Debt Instrument
Redemptions/maturities of power bonds		$ 1
Interest rate		3.77%
2001 Series D
Debt Instrument
Redemptions/maturities of power bonds		$ 525
Interest rate		4.88%
Total
Debt Instrument
Percent of par value		100.00%
Notes Payable [Member]
Debt Instrument
Interest rate		0.81%
Repayments of Notes Payable		$ 26
Debt of variable interest entities [Member]
Debt Instrument
Repayments of Other Long-term Debt		$ 17
Other Debt instrument, Interest Rate, Effective Percentage		4.30%
Total
Debt Instrument
Issues of power bonds		$ 999
2017 Series A
Debt Instrument
Issues of power bonds	[2]	1,000
Debt Instrument, Unamortized Discount (Premium), Net		$ (1)
[1]	All redemptions were at 100 percent of par.
[2]	The 2017 Series A bonds were issued at 99.9 percent of par.

Debt and Other Obligations Cred

Debt and Other Obligations Credit Facility Agreements (Details) $ in Millions	Mar. 31, 2017USD ($)Credit_facilities	Sep. 30, 2016USD ($)
Line of Credit
Credit Facility Agreements
Current borrowing capacity for credit facilities	$ 150
Total Cash Borrowings for Credit Facilities	0
Revolving Credit Facilities
Credit Facility Agreements
Current borrowing capacity for credit facilities	$ 2,650
Number of revolving credit facilities | Credit_facilities	4
December 2019 Credit Facility	$ 150
February 2021 Credit Facility	500
June 2020 Credit Facility	1,000
September 2020 Credit Facility	1,000
Cash Borrowings-December 2019 Credit Facility	0
Cash Borrowings-February 2021 Credit Facility	0
Cash Borrowings-June 2020 Credit Facility	0
Cash Borrowings-September 2020 Credit Facility	0
Total Cash Borrowings for Credit Facilities	0
Remaining Availability, December 2019 Credit Facility	112
Remaining Availability, February 2021 Credit Facility	0
Remaining Availability, June 2020 Credit Facility	722
Remaining Availability, September 2020 Credit Facility	712
Total Remaining Availability for Credit Facilities	1,546
Letter of Credit
Credit Facility Agreements
Letter of Credit Outstanding, December 2019 Credit Facility	38
Letter of Credit Outstanding, February 2021 Credit Facility	500
Letter of Credit Outstanding, June 2020 Credit Facility	278
Letter of Credit Outstanding, September 2020 Credit Facility	288
Amount of letters of credit outstanding for credit facilities	$ 1,100	$ 1,400

Debt and Other Obligations Leas

Debt and Other Obligations Lease/Leaseback Obligations (Details) $ in Millions	12 Months Ended
	Sep. 30, 2016USD ($)	Mar. 31, 2017USD ($)	Sep. 30, 2003Units
Debt Disclosure [Abstract]
Leasing transaction, number of units | Units			24
Percentage equity interests acquired	100.00%
Number of Businesses Acquired	2
Number of combustion units - Leaseback obligation	8
CT and QTE outstanding leaseback obligation | $	$ 467	$ 431

Accumulated Other Comprehensi50

Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2017	Mar. 31, 2016
Equity [Abstract]
Reclassification to earnings from cash flow hedges	[1]	$ (12)	$ 22	$ 26	$ 46
[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 $15 million of gains from AOCI to interest expense within the next twelve months to offset amounts anticipated to be recorded in interest expense related to net exchange gain on the debt.

Risk Management Activities an51

Risk Management Activities and Derivative Transactions Derivative Instruments That Receive Hedge Accounting Treatment (Details) - USD ($)		3 Months Ended		6 Months Ended
		Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2017	Mar. 31, 2016
Summary of Derivative Instruments That Receive Hedge Accounting Treatment
Net unrealized gain (loss) on cash flow hedges		$ 25,000,000	$ (27,000,000)	$ 17,000,000	$ (54,000,000)
Reclassification to earnings from cash flow hedges	[1]	(12,000,000)	22,000,000	26,000,000	46,000,000
Ineffective portion excluded from testing		$ 0	$ 0	0	$ 0
Reclassification to earnings from cash flow hedges in the next 12 months				$ (15,000,000)
[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 $15 million of gains from AOCI to interest expense within the next twelve months to offset amounts anticipated to be recorded in interest expense related to net exchange gain on the debt.

Risk Management Activities an52

Risk Management Activities and Derivative Transactions Derivative Instruments That Do Not Receive Hedge Accounting Treatment (Details)		3 Months Ended			6 Months Ended
		Mar. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Mar. 31, 2016USD ($)	Mar. 31, 2017USD ($)	Mar. 31, 2016USD ($)	Sep. 30, 2016USD ($)
Derivative
Amount recognized for unrealized gains (losses)			$ 0	$ 0	$ 0	$ 0
Change in Unrealized gains (losses) on Interest Rate Derivatives		$ (18,000,000)		(262,000,000)	459,000,000	(173,000,000)
Interest Rate Swap
Derivative
Gain (loss) recognized in income on derivatives	[1]	(26,000,000)		(27,000,000)	(52,000,000)	(55,000,000)
Commodity Contract Derivatives
Derivative
Gain (loss) recognized in income on derivatives	[1]	2,000,000		0	0	0
Fair value		(97,000,000)			(97,000,000)		$ (125,000,000)
Commodity derivatives under the financial trading program
Derivative
Gain (loss) recognized in income on derivatives	[1]	(6,000,000)		$ (21,000,000)	(21,000,000)	$ (56,000,000)
Fair value	[2]	$ (17,000,000)			$ (17,000,000)		$ (39,000,000)
Coal Contract Derivatives
Derivative
Number of contracts		19			19		20
Notional amount		21,000,000			21,000,000		20,000,000
Fair value		$ (113,000,000)			$ (113,000,000)		$ (127,000,000)
Natural gas contract derivatives
Derivative
Number of contracts		48			48		39
Notional amount		278,000,000			278,000,000		148,000,000
Fair value		$ 16,000,000			$ 16,000,000		$ 2,000,000
Natural gas contract derivatives
Derivative
Fair value		$ (17,000,000)			$ (17,000,000)		$ (39,000,000)
[1]	All of TVA's derivative instruments that do not receive hedge accounting treatment have unrealized gains (losses) that would otherwise be recognized in incomebut instead are deferred as regulatory assets and liabilities. As such, there was no related gain (loss) recognized in income for these unrealized gains (losses) for the three months and six months ended March 31, 2017 and 2016.
[2]	Fair values of certain derivatives under the FTP that were in net liability positions totaling $13 million and $30 million at March 31, 2017, and September 30, 2016, 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 an53

Risk Management Activities and Derivative Transactions Fair Values of TVA Derivatives (Details) - USD ($) $ in Millions		Mar. 31, 2017	Sep. 30, 2016
Derivatives, Fair Value
Gross amounts of recognized liabilities		$ 1,641	$ 2,145
200 million Sterling currency swap
Derivatives, Fair Value
Gross amounts of recognized liabilities	[1]	145	162
200 million Sterling currency swap | Other long-term liabilities
Derivatives, Fair Value
Fair value		(84)	(82)
250 million Sterling currency swap | Other long-term liabilities
Derivatives, Fair Value
Fair value		(34)	(41)
150 million Sterling currency swap | Other long-term liabilities
Derivatives, Fair Value
Fair value		(27)	(39)
$1.0 billion notional interest rate swap | Other long-term liabilities
Derivatives, Fair Value
Fair value		(1,072)	(1,387)
$476 million notional interest rate swap | Other long-term liabilities
Derivatives, Fair Value
Fair value		(398)	(539)
$42 million notional interest rate swap | Other long-term liabilities
Derivatives, Fair Value
Fair value		(9)	(12)
Commodity contract derivatives
Derivatives, Fair Value
Fair value		(97)	(125)
Commodity contract derivatives | Other long-term assets
Derivatives, Fair Value
Fair value		0	3
Commodity contract derivatives | Other current assets
Derivatives, Fair Value
Fair value		25	6
Commodity contract derivatives | Other long-term liabilities
Derivatives, Fair Value
Fair value		(33)	(49)
Commodity contract derivatives | Accounts payable and accrued liabilities
Derivatives, Fair Value
Fair value		(89)	(85)
Commodity derivatives under FTP
Derivatives, Fair Value
Fair value	[2]	(17)	(39)
Gross amounts of recognized liabilities		17	45
Commodity derivatives under FTP | Other current assets
Derivatives, Fair Value
Fair value		(13)	(30)
Commodity derivatives under FTP | Accounts payable and accrued liabilities
Derivatives, Fair Value
Fair value		(4)	(7)
Derivatives in net liability positions | Other current assets
Derivatives, Fair Value
Gross amounts of recognized liabilities		13	30
Derivatives in net liability positions | Other long-term liabilities
Derivatives, Fair Value
Fair value		$ 0	$ (2)
[1]	Letters of credit of approximately $1.1 billion and $1.4 billion were posted as collateral at March 31, 2017, and September 30, 2016, 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.
[2]	Fair values of certain derivatives under the FTP that were in net liability positions totaling $13 million and $30 million at March 31, 2017, and September 30, 2016, respectively, are recorded in TVA's margin cash accounts in Other current assets. These derivatives are transacted with futures commission merchants, and cash deposits have been posted to the margin cash accounts held with each futures commission merchant to offset the net liability positions in full.

Risk Management Activities an54

Risk Management Activities and Derivative Transactions Currency Swaps Outstanding (Details) £ in Millions	6 Months Ended
	Mar. 31, 2017GBP (£)Bond_issues
Derivative
Number of British pound sterling denominated bond transactions	3
Number of currency swaps outstanding	3
Associated TVA bond issues currency exposure | £	£ 600
Minimum
Derivative
Expiration date range of swaps	2,021
Maximum
Derivative
Expiration date range of swaps	2,043

Risk Management Activities an55

Risk Management Activities and Derivative Transactions Derivatives Under FTP (Details) $ in Millions		3 Months Ended		6 Months Ended
		Mar. 31, 2017USD ($)	Mar. 31, 2016USD ($)	Mar. 31, 2017USD ($)	Mar. 31, 2016USD ($)	Sep. 30, 2016USD ($)
Derivative
Forward Contract Derivative Asset, at Fair Value		$ 10		$ 10		$ 15
Coal Contract
Derivative
Notional amount		21,000,000		21,000,000		20,000,000
Fair value		$ (113)		$ (113)		$ (127)
Natural Gas Contract Derivatives
Derivative
Notional amount		278,000,000		278,000,000		148,000,000
Fair value		$ 16		$ 16		$ 2
Closed derivative contracts
Derivative
Fair value		(2)		(2)		(5)
Natural Gas Contract Derivatives
Derivative
Fair value		(17)		(17)		$ (39)
Decrease (increase) in fuel expense		(5)	$ (17)	(17)	$ (45)
Decrease (increase) in purchased power expense		$ (1)	$ (4)	$ (4)	$ (11)
Natural Gas swap
Derivative
Notional amount	[1]	11,200,000		11,200,000		21,052,500
Fair value	[1]	$ (17)		$ (17)		$ (39)
Fair Value, Inputs, Level 2
Derivative
Forward Contract Derivative Asset, at Fair Value		$ 10		$ 10		$ 15
[1]	Fair value amounts presented are based on the net commodity position with the counterparty. Notional amounts disclosed represent the net value of contractual amounts.

Risk Management Activities an56

Risk Management Activities and Derivative Transactions Offsetting of Derivative Assets (Details) - USD ($) $ in Millions		Mar. 31, 2017	Sep. 30, 2016
Offsetting Assets [Line Items]
Gross Amounts Offset in the Balance Sheet	[1]		$ (6)
Net Amounts of Assets Presented in the Balance Sheet	[2]		9
Total derivatives not subject to master netting or similar arrangement	[2]	$ 25	9
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement			15
Letter of Credit
Offsetting Assets [Line Items]
Amount of letters of credit outstanding for credit facilities		$ 1,100	1,400
Commodity derivatives under FTP
Offsetting Assets [Line Items]
Gross Amounts of Recognized Assets			6
Gross Amounts Offset in the Balance Sheet	[1]		(6)
Net Amounts of Assets Presented in the Balance Sheet	[2]		$ 0
[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 that are not offset in the consolidated balance sheets.

Risk Management Activities an57

Risk Management Activities and Derivative Transactions Offsetting for Derivative Liabilities (Details) - USD ($) $ in Millions		Mar. 31, 2017	Sep. 30, 2016
Offsetting Liabilities [Line Items]
Derivative Asset, Not Subject to Master Netting Arrangement	[1]	$ 25	$ 9
Gross amounts of recognized liabilities		1,641	2,145
Gross Amounts Offset in the Balance Sheet	[2]	(13)	(36)
Net Amounts of Liabilities Presented in the Balance Sheet	[1]	1,750	2,243
Commodity derivatives not subject to master netting or similar arrangement	[1]	122	134
Total		1,763	2,279
Forward Contract Derivative Asset, at Fair Value		10	15
Currency Swap
Offsetting Liabilities [Line Items]
Gross amounts of recognized liabilities	[3]	145	162
Gross Amounts Offset in the Balance Sheet	[2],[3]	0	0
Net Amounts of Liabilities Presented in the Balance Sheet	[1],[3]	145	162
Interest Rate Contract
Offsetting Liabilities [Line Items]
Gross amounts of recognized liabilities	[3]	1,479	1,938
Gross Amounts Offset in the Balance Sheet	[2],[3]	0	0
Net Amounts of Liabilities Presented in the Balance Sheet	[1],[3]	1,479	1,938
Commodity derivatives under FTP
Offsetting Liabilities [Line Items]
Gross amounts of recognized liabilities		17	45
Gross Amounts Offset in the Balance Sheet	[2]	(13)	(36)
Net Amounts of Liabilities Presented in the Balance Sheet	[1]	4	9
Total derivatives subject to master netting or similar arrangement
Offsetting Liabilities [Line Items]
Net Amounts of Liabilities Presented in the Balance Sheet	[1]	1,628	2,109
Letter of Credit
Offsetting Liabilities [Line Items]
Amount of letters of credit outstanding		1,100	1,400
Fair Value, Inputs, Level 2
Offsetting Liabilities [Line Items]
Forward Contract Derivative Asset, at Fair Value		$ 10	$ 15
[1]	There are no derivative contracts subject to a master netting arrangement or similar agreement that are not offset in the consolidated balance sheets.
[2]	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.
[3]	Letters of credit of approximately $1.1 billion and $1.4 billion were posted as collateral at March 31, 2017, and September 30, 2016, 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.

Risk Management Activities an58

Risk Management Activities and Derivative Transactions Collateral (Details) - USD ($) $ in Millions	Mar. 31, 2017	Sep. 30, 2016
Derivative
Likely cash collateral obligation increase	$ 22
Securities Pledged as Collateral [Member]
Derivative
Derivative, Net Liability Position, Aggregate Fair Value	1,600
Derivative, Collateral, Right to Reclaim Cash	1,100
Letter of Credit
Derivative
Amount of letters of credit outstanding	$ 1,100	$ 1,400

Risk Management Activities an59

Risk Management Activities and Derivative Transactions Counterparty Credit Risk (Details) $ in Millions		Mar. 31, 2017USD ($)merchantsmegawatts	Sep. 30, 2016USD ($)
Derivative
Number of active future commission merchants | merchants		2
Coal counterparties in asset position	[1]		$ 9
Megawatts of Power Purchase Agreement
Derivative
Megawatts | megawatts		440
Coal Contract
Derivative
Coal counterparties in asset position		$ 3
[1]	There are no derivative contracts subject to a master netting arrangement or similar agreement that are not offset in the consolidated balance sheets.

Fair Value Measurements Fair Va

Fair Value Measurements Fair Value Measurements - Investments (Details) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2017USD ($)	Mar. 31, 2016USD ($)	Mar. 31, 2017USD ($)	Mar. 31, 2016USD ($)
Investment Gains (Losses)
Investment fund securities classified as trading and measured at fair value	$ 2,400		$ 2,400
Balance in NDT	1,800		1,800
Balance in ART	$ 545		$ 545
Period of time where the investor contributes capital to an investment in a private partnership - minimum			three
Period of time where the investor contributes capital to an investment in a private partnership - maximum			four
Minimum investment period			10 years
Number of readily available quoted exchange prices for the investments	0		0
SERP
Investment Gains (Losses)
Unrealized gains (losses) on investments	$ 2	$ 0	$ 1	$ 0
LTDCP
Investment Gains (Losses)
Unrealized gains (losses) on investments	1	0	0	0
NDT
Investment Gains (Losses)
Unrealized gains (losses) on investments	42	9	35	48
ART
Investment Gains (Losses)
Unrealized gains (losses) on investments	19	$ (3)	22	$ 9
Equity Funds
Investment Gains (Losses)
NDT unfunded commitments related to private equity and real estate	59		59
Real Estate Funds
Investment Gains (Losses)
NDT unfunded commitments related to private equity and real estate	$ 5		$ 5

Fair Value Measurements Fair 61

Fair Value Measurements Fair Value Measurements - Nonperformance Risk (Details) $ in Millions	Mar. 31, 2017USD ($)
Nonperformance Risk
Derivative credit valuation adjustment, assets	$ 1
Derivative credit valuation adjustment, liabilities	$ 1

Fair Value Measurements Fair 62

Fair Value Measurements Fair Value Measurements (Details) - USD ($) $ in Millions		Mar. 31, 2017	Sep. 30, 2016
Investments
Equity securities		$ 205	$ 196
Government debt securities		134	124
Corporate debt securities		408	393
Mortgage and asset-backed securities		46	50
Institutional mutual funds		83	92
Forward debt securities contracts		10	15
Private equity funds measured at net asset value(1)	[1]	139	132
Private real estate funds measured at net asset value(1)	[1]	112	113
Commingled funds measured at net asset value(1)	[1]	1,251	1,142
Total investments		2,388	2,257
Commodity contract derivatives		25	9
Total		2,413	2,266
Liabilities
Currency swap(s)	[2]	145	162
Interest rate swaps		1,479	1,938
Commodity contract derivatives		122	134
Swap contracts	[2]	4	9
Total		1,750	2,243
Fair Value, Inputs, Level 1
Investments
Equity securities		205	196
Government debt securities		76	88
Corporate debt securities		0	0
Mortgage and asset-backed securities		0	0
Institutional mutual funds		83	92
Forward debt securities contracts		0	0
Private equity funds measured at net asset value(1)	[1]	0	0
Private real estate funds measured at net asset value(1)	[1]	0	0
Commingled funds measured at net asset value(1)	[1]	0	0
Total investments		364	376
Commodity contract derivatives		0	0
Total		364	376
Liabilities
Currency swap(s)	[2]	0	0
Interest rate swaps		0	0
Commodity contract derivatives		0	0
Swap contracts	[2]	0	0
Total		0	0
Fair Value, Inputs, Level 2
Investments
Equity securities		0	0
Government debt securities		58	36
Corporate debt securities		408	393
Mortgage and asset-backed securities		46	50
Institutional mutual funds		0	0
Forward debt securities contracts		10	15
Private equity funds measured at net asset value(1)	[1]	0	0
Private real estate funds measured at net asset value(1)	[1]	0	0
Commingled funds measured at net asset value(1)	[1]	0	0
Total investments		522	494
Commodity contract derivatives		22	5
Total		544	499
Liabilities
Currency swap(s)	[2]	145	162
Interest rate swaps		1,479	1,938
Commodity contract derivatives		6	3
Swap contracts	[2]	4	9
Total		1,634	2,112
Fair Value, Inputs, Level 3
Investments
Equity securities		0	0
Government debt securities		0	0
Corporate debt securities		0	0
Mortgage and asset-backed securities		0	0
Institutional mutual funds		0	0
Forward debt securities contracts		0	0
Private equity funds measured at net asset value(1)	[1]	0	0
Private real estate funds measured at net asset value(1)	[1]	0	0
Commingled funds measured at net asset value(1)	[1]	0	0
Total investments		0	0
Commodity contract derivatives		3	4
Total		3	4
Liabilities
Currency swap(s)	[2]	0	0
Interest rate swaps		0	0
Commodity contract derivatives		116	131
Swap contracts	[2]	0	0
Total		$ 116	$ 131
[1]	Certain investments that are measured at fair value using the net asset value per share (or its equivalent) practical expedient have not been categorized in the fair value hierarchy. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the amounts presented in the consolidated balance sheets.
[2]	Due to the right of setoff and method of settlement, TVA elects to record commodity derivatives under the FTP based on its net commodity position with the counterparty or FCM. Deposits are made to TVA's margin cash accounts held with each FCM to offset any net liability positions in full for derivatives that are transacted with FCMs. TVA records currency swaps net of cash collateral received from or paid to the counterparty, to the extent such amount is not recorded in Accounts payable and accrued liabilities. See Note 12 — Offsetting of Derivative Assets and Liabilities.

Fair Value Measurements Fair 63

Fair Value Measurements Fair Value Measurements Using Significant Unobservable Inputs (Details) tons-per-year in Billions	3 Months Ended		6 Months Ended
	Mar. 31, 2017USD ($)tons-per-year	Dec. 31, 2015USD ($)	Mar. 31, 2017USD ($)tons-per-year	Mar. 31, 2016USD ($)	Dec. 31, 2016USD ($)	Sep. 30, 2016USD ($)tons-per-year	Sep. 30, 2015USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Commodity contract derivatives	$ 25,000,000		$ 25,000,000			$ 9,000,000
Commodity contract derivatives	$ 122,000,000		$ 122,000,000			$ 134,000,000
Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value measurements tons per year | tons-per-year	0.8		0.8			0.8
Price per ton	$ 109.55		$ 109.55			$ 85.02
Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value measurements tons per year | tons-per-year	0.6		0.6			0.7
Price per ton	$ 11.45		$ 11.45			$ 11.80
Fair Value, Inputs, Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Commodity contract derivatives	3,000,000		3,000,000			4,000,000
Commodity contract derivatives	116,000,000		116,000,000			131,000,000
Commodity Contract Derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Balance	(112,000,000)	$ (123,000,000)	(112,000,000)	$ (187,000,000)	$ (104,000,000)	$ (127,000,000)	$ (98,000,000)
Net unrealized gains (losses) deferred as regulatory assets and liabilities	$ (8,000,000)	$ (64,000,000)	$ 15,000,000	$ (89,000,000)

Fair Value Measurements Estimat

Fair Value Measurements Estimated Values of Financial Instruments Not Recorded at Fair Value (Details) - USD ($) $ in Millions	Mar. 31, 2017	Sep. 30, 2016
Estimated Values of Financial Intruments Not Recorded at Fair Value
EnergyRight® receivables (including current portion)	$ 138	$ 144
Loans and other long-term receivables, net (including current portion)	150	130
EnergyRight® financing obligation (including current portion)	175	183
Unfunded loan commitments	14	17
Membership interest of variable interest entity subject to mandatory redemption (including current portion)	42	46
Long-term outstanding power bonds (including current maturities), net	26,983	28,620
Long-term debt of variable interest entities (including current maturities), net	1,353	1,468
Long-term notes payable (including current maturities)	49	75
Carrying Value
Estimated Values of Financial Intruments Not Recorded at Fair Value
EnergyRight® receivables (including current portion)	135	141
Loans and other long-term receivables, net (including current portion)	161	141
EnergyRight® financing obligation (including current portion)	156	163
Unfunded loan commitments	0	0
Membership interest of variable interest entity subject to mandatory redemption (including current portion)	33	35
Long-term outstanding power bonds (including current maturities), net	22,906	22,456
Long-term debt of variable interest entities (including current maturities), net	1,217	1,234
Long-term notes payable (including current maturities)	$ 49	$ 75

Other Income (Expense), Net (De

Other Income (Expense), Net (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2017	Mar. 31, 2016
Other Income (Expense), Net
External services	$ 5	$ 3	$ 8	$ 7
Interest income	6	6	11	12
Gains (losses) on investments	4	0	4	3
Miscellaneous - income	0		4
Miscellaneous - expense		(1)		(2)
Total other income (expense), net	$ 15	$ 8	$ 27	$ 20

Benefit Plans Components of Ben

Benefit Plans Components of Benefit Plans (Details)	6 Months Ended
	Mar. 31, 2017plans
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 ($)	3 Months Ended		6 Months Ended			12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Sep. 30, 2017	Mar. 31, 2017	Mar. 31, 2016	Sep. 30, 2017	Sep. 30, 2016
Other Pension Plan
Defined Benefit Plan Disclosure
Defined benefit plan contributions				$ 150,000,000			$ 275,000,000
Pension Benefits
Defined Benefit Plan Disclosure
Service cost	$ 13,000,000	$ 34,000,000		30,000,000	$ 66,000,000
Interest cost	116,000,000	142,000,000		232,000,000	282,000,000
Expected return on plan assets	(114,000,000)	(112,000,000)		(228,000,000)	(223,000,000)
Amortization of prior service cost	(24,000,000)	(5,000,000)		(49,000,000)	(11,000,000)
Recognized net actuarial loss	120,000,000	82,000,000		236,000,000	155,000,000
Total net periodic benefit cost as actuarially determined	111,000,000	141,000,000		221,000,000	269,000,000
Amount capitalized due to actions of regulator	(34,000,000)	(71,000,000)		(68,000,000)	(129,000,000)
Total net periodic benefit cost	77,000,000	70,000,000		153,000,000	140,000,000
Other Post-retirement Benefits
Defined Benefit Plan Disclosure
Defined benefit plan contributions				17,000,000	21,000,000
Service cost	5,000,000	4,000,000		9,000,000	8,000,000
Interest cost	4,000,000	8,000,000		11,000,000	15,000,000
Expected return on plan assets	0	0		0	0
Amortization of prior service cost	(10,000,000)	(2,000,000)		(11,000,000)	(3,000,000)
Recognized net actuarial loss	5,000,000	1,000,000		7,000,000	3,000,000
Total net periodic benefit cost as actuarially determined	4,000,000	11,000,000		16,000,000	23,000,000
Amount capitalized due to actions of regulator	0	0		0	0
Total net periodic benefit cost	$ 4,000,000	$ 11,000,000		$ 16,000,000	$ 23,000,000
Scenario, Forecast | Other Pension Plan
Defined Benefit Plan Disclosure
Defined benefit plan contributions			$ 150,000,000			$ 300,000,000

Benefit Plans Contributions (De

Benefit Plans Contributions (Details) - USD ($)	6 Months Ended			12 Months Ended
	Sep. 30, 2017	Mar. 31, 2017	Mar. 31, 2016	Sep. 30, 2017	Sep. 30, 2016
Defined Benefit Plan Disclosure
Defined contribution plan contributions		$ 42,000,000	$ 20,000,000
Other Pension Plan
Defined Benefit Plan Disclosure
Defined benefit plan contributions		150,000,000			$ 275,000,000
Other Post-retirement Benefits
Defined Benefit Plan Disclosure
Defined benefit plan contributions		$ 17,000,000	$ 21,000,000
Scenario, Forecast | Other Pension Plan
Defined Benefit Plan Disclosure
Defined benefit plan contributions	$ 150,000,000			$ 300,000,000

Contingencies and Legal Proce69

Contingencies and Legal Proceedings Contingencies (Details) $ in Thousands	6 Months Ended
	Mar. 31, 2017reactors	Mar. 31, 2017Units	Mar. 31, 2017USD ($)		Mar. 31, 2017Insurance_layers	Mar. 31, 2017Procedures	Mar. 31, 2017Sites	Sep. 30, 2016USD ($)
Loss Contingencies
Nuclear liability insurance			$ 450,000
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		7
Maximum assessment per nuclear incident			891,000
Maximum payment required per accident in any one year			133,000
Total amount of protection available			13,000,000
Surcharge for legal expenses	5.00%
Number of layers before Congress is required to take action | Insurance_layers					2
Amount of property, decommissioning, and decontamination insurance carried			5,100,000
Amount of insurance available for loss at any one site			2,100,000
Number of sites	2						1
Maximum amount of retrospective premiums			132,000
Maximum idemnity if a covered accident takes or keeps a nuclear unit offline			490,000
Maximum retrospective premiums			37,000
Estimated future decommissioning cost			4,115,000	[1]				$ 4,052,000
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			300,000
Possible additional future costs for compliance with CCR requirements			1,100,000
Possible additional future costs for compliance with Clean Water requirements.			500,000
Total amount liability settled for			10
Estimated liability for cleanup and environmental work			27,000					23,000
Nuclear
Loss Contingencies
Estimated future decommissioning cost			2,550,000					2,492,000
Non-nuclear
Loss Contingencies
Estimated future decommissioning cost			$ 1,565,000					$ 1,560,000
[1]	The current portion of ARO in the amount of $200 million and $212 million is included in Accounts payable and accrued liabilities at March 31, 2017, and September 30, 2016, respectively.

Contingencies and Legal Proce70

Contingencies and Legal Proceedings Legal Proceedings (Details)	6 Months Ended
	Mar. 31, 2017USD ($)PeopleUnitsmegawattsGroupsYearsAgreements
Legal Proceedings
TDEC civil penalties related to Gallatin	$ 17,000
ERROR in label resolution.	37,500
General
Legal Proceedings
Legal loss contingency accrual	$ 40,000,000
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 environmental advocacy groups | Groups	3
Number of units to be idled | Units	18
Megawatts | megawatts	2,200
Megawatts option 2	3,500
Amount to be invested in certain TVA environmental projects	$ 290,000,000
Amount to be provided to fund environmental projects	60,000,000
Amount to pay civil penalties	$ 10,000,000
Case Involving Tennessee Valley Authority Retirement System
Legal Proceedings
Number of participants that filed suit | People	8
Contribution from TVA	$ 1,000,000,000
Retirement age of eligibility for cost of living adjustment before January 1, 2010 | Years	55
Retirement age of eligibility for cost of living adjustment after January 1, 2010 | Years	60
Other long-term liabilities | General
Legal Proceedings
Legal loss contingency accrual	$ 16,000,000
Accounts payable and accrued liabilities | General
Legal Proceedings
Legal loss contingency accrual	$ 24,000,000