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Asset Retirement Obligations (Details) - USD ($) $ in Millions | 9 Months Ended |
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Jun. 30, 2021 | Sep. 30, 2020
Asset Retirement Obligations |  |
Asset Retirement Obligation, Period Increase (Decrease) | $ 167 |
Amortization and Depreciation of Decontaminating and Decommissioning Assets | 54 |
Asset Retirement Obligation, Beginning Balance | 6,785 |
Settlements | (140) |
Asset Retirement Obligation, Revision of Estimate | 119 |
Accretion (recorded as regulatory asset) | 158 |
Asset Retirement Obligation, Ending Balance | 6,952 |
Current portion of ARO | (306) | $ (345)
Nuclear |  |
Asset Retirement Obligations |  |
Asset Retirement Obligation, Beginning Balance | 3,278 |
Settlements | (5) |
Asset Retirement Obligation, Revision of Estimate | 12 |
Accretion (recorded as regulatory asset) | 111 |
Asset Retirement Obligation, Ending Balance | 3,396 |
Non-nuclear |  |
Asset Retirement Obligations |  |
Asset Retirement Obligation, Beginning Balance | 3,507 |
Settlements | (135) |
Asset Retirement Obligation, Revision of Estimate | 107 |
Accretion (recorded as regulatory asset) | 47 |
Asset Retirement Obligation, Ending Balance | $ 3,556 |
Accounts payable and accrued liabilities |  |
Asset Retirement Obligations |  |
Current portion of ARO |  | $ (345)

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- Definition The current period expense charged against earnings on decontaminating and decommissioning of facilities used in the normal conduct of business and not intended for resale to allocate or recognize the cost of the assets over their useful lives. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=123570139&loc=d3e3602-108585 + Details
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- Definition The carrying amount of a liability for an asset retirement obligation. An asset retirement obligation is a legal obligation associated with the disposal or retirement 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 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=6392692&loc=d3e7535-110849 + Details
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- Definition Current portion of the carrying amount of a liability for an asset retirement obligation. An asset retirement obligation is a legal obligation associated with the disposal or retirement 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 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=6392692&loc=d3e7535-110849 + Details
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- Definition Amount of asset retirement obligations settled, or otherwise disposed of, during the period. This may include asset retirement obligations transferred to third parties associated with the sale of a long-lived asset. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 410 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=6392692&loc=d3e7535-110849 + Details
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