Maximum potential amount of future payments (undiscounted) the guarantor could be required to make under the guarantee or each group of similar guarantees before reduction for potential recoveries under recourse or collateralization provisions.

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The minimum amount the entity agreed to spend under the long-term purchase commitment.

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Amount of expected credit loss for credit exposure on off-balance-sheet commitment, including but not limited to, loan commitment, standby letter of credit, financial guarantee not accounted for as insurance. Excludes off-balance sheet credit exposure accounted for as insurance and instrument accounted for under derivatives and hedging.

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
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Commitments And Contingencies (Narrative) (Details) - USD ($) $ in Millions	6 Months Ended	9 Months Ended
	Jun. 30, 2023	Sep. 30, 2021	Sep. 30, 2020
Commitments and Contingencies [Line Items]
Minimum future commitments	$ 1,352
IPL [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	624
WPL [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	698
Capital Purchase Commitment [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	188
Capital Purchase Commitment [Member] \| IPL [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	87
Capital Purchase Commitment [Member] \| WPL [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	101
Indemnification Agreement [Member]
Commitments and Contingencies [Line Items]
Obligations, maximum	59
Indemnification Agreement [Member] \| Purchased Power [Member]
Commitments and Contingencies [Line Items]
Obligations, maximum	$ 17
Whiting Petroleum Affiliate [Member]
Commitments and Contingencies [Line Items]
Partnership share, percent	6.00%
Obligations, maximum	$ 58
Credit loss liability	$ 5
Federal Energy Regulatory Commission [Member]
Commitments and Contingencies [Line Items]
MISO base return on equity, percentage		10.02%	9.88%