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Asset Retirement Obligations | 6 Months Ended
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Mar. 31, 2020
Asset Retirement Obligation Disclosure [Abstract] |
Asset Retirement Obligations | Asset Retirement Obligations During the six months ended March 31, 2020, TVA's total asset retirement obligations ("ARO") liability increased $159 million as a result of periodic accretion and revisions in estimate, partially offset by settlement projects that were conducted during the period. The nuclear and non-nuclear accretion amounts were deferred as regulatory assets. During the six months ended March 31, 2020, $84 million of the related regulatory assets were amortized into expense as these amounts were collected in rates. See Note 8 — Regulatory Assets and Liabilities. TVA maintains investment trusts to help fund its decommissioning obligations. See Note 15 — Fair Value Measurements — Investment Funds and Note 20 — Contingencies and Legal Proceedings — Contingencies — Decommissioning Costs for disclosure of the current balances of the trusts and a discussion of the trusts' objectives.
Asset Retirement Obligation Activity(1)
| Nuclear |  | Non-Nuclear |  | Total
Balance at September 30, 2019 | $ | 3,136 |  |  | $ | 2,480 |  |  | $ | 5,616 |
Settlements | — |  |  | (62 | ) |  | (62 | )
Revisions in estimate | — |  |  | 120 |  |  | 120 |
Accretion (recorded as regulatory asset) | 70 |  |  | 31 |  |  | 101 |
Balance at March 31, 2020 | $ | 3,206 |  |  | $ | 2,569 |  |  | $ | 5,775 |
Note (1) The current portions of the ARO liability in the amounts of $193 million and $163 million at March 31, 2020, and September 30, 2019, respectively, are included in Accounts payable and accrued liabilities. The revisions in non-nuclear estimates increased $120 million for the six months ended March 31, 2020. In November 2019, the Tennessee Department of Environment and Conservation ("TDEC") released amendments to its regulations which govern solid waste disposal facilities, including TVA's active Coal Combustion Residuals ("CCR") facilities covered by a solid waste disposal permit and those which closed pursuant to a TDEC approved closure plan. Such facilities are generally subject to a 30-year post-closure care period during which the owner or operator must undertake certain activities, including monitoring and maintaining the facility. The amendments will, among other things, add an additional 50-year period after the end of the post-closure care period, require TVA to submit recommendations as to what activities must be performed during this 50-year period to protect human health and the environment, and require TVA to submit revised closure plans every 10 years. This regulatory revision resulted in an increase of $129 million, of which $38 million was related to operating CCR facilities and $91 million was related to inactive or closed CCR facilities.

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- Definition The entire disclosure for an asset retirement obligation and the associated long-lived asset. An asset retirement obligation is a legal obligation associated with the disposal or retirement from service of a tangible long-lived asset that results from the acquisition, construction or development, or the normal operations of a long-lived asset, except for certain obligations of lessees. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 410 -SubTopic 20 -URI http://asc.fasb.org/subtopic&trid=2175671 + Details
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