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Asset Retirement Obligations (Details) - USD ($) $ in Millions	9 Months Ended
	Jun. 30, 2023	Sep. 30, 2022
Asset Retirement Obligations
Asset Retirement Obligation, Period Increase (Decrease)	$ (40)
Amortization and Depreciation of Decontaminating and Decommissioning Assets	141
Asset Retirement Obligation, Beginning Balance	7,162
Settlements	(195)
Asset Retirement Obligation, Revision of Estimate	(22)
Accretion (recorded as regulatory asset)	177
Asset Retirement Obligation, Ending Balance	7,122
Current portion of ARO	(262)	$ (275)
Asset Retirement Obligation, Revision of Estimate	9
Changes in closure liabilities	15
Nuclear
Asset Retirement Obligations
Asset Retirement Obligation, Beginning Balance	3,643
Settlements	0
Asset Retirement Obligation, Revision of Estimate	6
Accretion (recorded as regulatory asset)	124
Asset Retirement Obligation, Ending Balance	3,773
Non-nuclear
Asset Retirement Obligations
Asset Retirement Obligation, Beginning Balance	3,519
Settlements	(195)
Asset Retirement Obligation, Revision of Estimate	(28)
Accretion (recorded as regulatory asset)	53
Asset Retirement Obligation, Ending Balance	$ 3,349

X

- Definition

The amount of accretion recorded as a regulatory asset during the period.

+ References

No definition available.

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- Definition

Changes in closure liabilities

+ References

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- Definition

Increase in Asset Retirement Obligation, Revisions in Estimate

+ References

No definition available.

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- Definition

Reconciliation of Asset Retirement Obligations [Line Items]

+ References

No definition available.

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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
-Topic 230
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 28
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482740/230-10-45-28

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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://www.xbrl.org/2003/role/disclosureRef
-Topic 410
-SubTopic 20
-Name Accounting Standards Codification
-Section 25
-Paragraph 4
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481999/410-20-25-4

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 410
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481850/410-20-50-1

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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://www.xbrl.org/2009/role/commonPracticeRef
-Topic 410
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481850/410-20-50-1

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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://www.xbrl.org/2003/role/disclosureRef
-Topic 410
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (c)(2)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481850/410-20-50-1

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- Definition

Amount of increase (decrease) in asset retirement obligations.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 410
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481850/410-20-50-1

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- Definition

Amount of increase (decrease) in the asset retirement obligation from changes in the amount or timing of the estimated cash flows associated with the settlement of the obligation.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 410
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (c)(4)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481850/410-20-50-1

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