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Risk Management Activities and Derivative Transactions Derivatives Under FTP (Details) - USD ($) $ in Millions	Mar. 31, 2025	Sep. 30, 2024
Derivative
Forward Contract Derivative Asset, at Fair Value	$ 16	$ 11
Fair value	13	64
Commodity Contract under FHP
Derivative
Fair value	95	(161)
Fair Value, Inputs, Level 2
Derivative
Forward Contract Derivative Asset, at Fair Value	$ 16	$ 11

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- Definition

Fair value as of the balance sheet date of forward contract derivative assets.

+ References

No definition available.

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- Definition

Fair value of the assets less the liabilities of a derivative or group of derivatives.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 825
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 10
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482907/825-10-50-10

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 815
-SubTopic 40
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Subparagraph (f)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480237/815-40-50-5

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