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Debt and Other Obligations Lease/Leaseback Obligations (Details) $ in Millions	3 Months Ended	6 Months Ended		12 Months Ended
	Mar. 31, 2023 USD ($)	Sep. 30, 2023 USD ($)	Mar. 31, 2023 USD ($)	Sep. 30, 2024 USD ($)	Sep. 30, 2022
Sale Leaseback Transaction [Line Items]
CT and QTE outstanding leaseback obligation	$ 0		$ 0
Leasing transaction, number of units					16
Leasing transaction, number of units					16
CT and QTE outstanding leaseback obligation	0		0
Lagoon Creek
Sale Leaseback Transaction [Line Items]
Amortization of reacquired rights	1
Lagoon Creek | Forecast
Sale Leaseback Transaction [Line Items]
Amortization of reacquired rights		$ 1		$ 3
Kemper/Lagoon Creek leasehold interests
Sale Leaseback Transaction [Line Items]
leasehold interest	155
leasehold interest	$ 155
Lagoon Creek
Sale Leaseback Transaction [Line Items]
leasehold interest			78
leasehold interest			$ 78
Kemper/Lagoon Creek leasehold interests
Sale Leaseback Transaction [Line Items]
Leasing transaction, number of units					8
Leasing transaction, number of units					8

X

- Definition

Amortization of reacquired rights

+ References

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+ Details

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X

- Definition

The outstanding leaseback obligations related to combustion turbine units and qualified technological equipment and software.

+ References

No definition available.

+ Details

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X

- Definition

The number of units involved in leaseback transactions.

+ References

No definition available.

+ Details

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X

- Definition

leasehold interest

+ References

No definition available.

+ Details

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X

- 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

No definition available.

+ Details

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- Details

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- Details

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- Details

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- Details

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