Concentration Risk Threshold Percentage

No definition available.

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Namespace Prefix:	lnt_
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Period Type:	instant

- Definition

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.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 460
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Subparagraph (b)(1)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482425/460-10-50-4

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Percentage investment held by members or limited partners of limited liability company (LLC) or limited partnership (LP).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 272
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482987/272-10-50-3

+ Details

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Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

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

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- 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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Balance Type:	na
Period Type:	duration

- Definition

Percentage of public utility's approved return on equity.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Details

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Namespace Prefix:
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- Details

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Namespace Prefix:
Data Type:	na
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- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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Namespace Prefix:
Data Type:	na
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- Details

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Namespace Prefix:
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Balance Type:
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- Details

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- Details

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- Details

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- Details

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Namespace Prefix:
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- Details

Name:	us-gaap_LongTermPurchaseCommitmentByCategoryOfItemPurchasedAxis=lnt_RenewableTaxCreditsTransferredMember
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Commitments And Contingencies (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Jun. 30, 2024
Commitments and Contingencies [Line Items]
Minimum future commitments			$ 1,046
IPL [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments			472
WPL [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments			$ 531
Workforce Subject to Collective Bargaining Arrangements [Member]
Commitments and Contingencies [Line Items]
Employees covered by collective bargaining agreement, percentage			53.00%
Workforce Subject to Collective Bargaining Arrangements [Member] \| IPL [Member]
Commitments and Contingencies [Line Items]
Employees covered by collective bargaining agreement, percentage			70.00%
Workforce Subject to Collective Bargaining Arrangements [Member] \| WPL [Member]
Commitments and Contingencies [Line Items]
Employees covered by collective bargaining agreement, percentage			83.00%
Workforce Subject to Collective Bargaining Arrangements Expiring within One Year [Member]
Commitments and Contingencies [Line Items]
Employees covered by collective bargaining agreement, percentage			18.00%
Workforce Subject to Collective Bargaining Arrangements Expiring within One Year [Member] \| IPL [Member]
Commitments and Contingencies [Line Items]
Employees covered by collective bargaining agreement, percentage			54.00%
Federal Energy Regulatory Commission [Member]
Commitments and Contingencies [Line Items]
MISO base return on equity, percentage	10.02%	9.88%
Indemnification Agreement [Member]
Commitments and Contingencies [Line Items]
Obligations, maximum			$ 51
Whiting Petroleum Affiliate [Member]
Commitments and Contingencies [Line Items]
Partnership share, percent			6.00%
Obligations, maximum			$ 49
Capital Purchase Commitment [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments			116
Capital Purchase Commitment [Member] \| IPL [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments			38
Capital Purchase Commitment [Member] \| WPL [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments			76
Purchased Power [Member] \| Indemnification Agreement [Member]
Commitments and Contingencies [Line Items]
Obligations, maximum			17
Renewable Tax Credits Transferred [Member] \| Indemnification Agreement [Member] \| IPL [Member]
Commitments and Contingencies [Line Items]
Obligations, maximum			147
Renewable Tax Credits Transferred [Member] \| Indemnification Agreement [Member] \| WPL [Member]
Commitments and Contingencies [Line Items]
Obligations, maximum			$ 50