XML 86 R66.htm IDEA: XBRL DOCUMENT v3.25.3

Commitments And Contingencies (Other Purchase Commitments) (Details) $ in Millions	9 Months Ended
	Sep. 30, 2025 USD ($)
Commitments and Contingencies [Line Items]
Minimum future commitments	$ 1,138
Individual commitments incurred	1
IPL [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	593
Individual commitments incurred	1
WPL [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	513
Individual commitments incurred	1
Natural gas [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	879
Natural gas [Member] | IPL [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	489
Natural gas [Member] | WPL [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	390
Coal [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	149
Coal [Member] | IPL [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	52
Coal [Member] | WPL [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	97
Other [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	110
Other [Member] | IPL [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	52
Other [Member] | WPL [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	$ 26

X

- Definition

Individual commitments incurred in excess of $1 million

+ References

No definition available.

+ Details

Name:	lnt_IndividualCommitmentsIncurred
Namespace Prefix:	lnt_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

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

+ References

No definition available.

+ Details

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

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

Name:	us-gaap_LongTermPurchaseCommitmentLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Details

Name:	dei_LegalEntityAxis=lnt_IplMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	dei_LegalEntityAxis=lnt_WplMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_LongTermPurchaseCommitmentByCategoryOfItemPurchasedAxis=us-gaap_PublicUtilitiesInventoryNaturalGasMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_LongTermPurchaseCommitmentByCategoryOfItemPurchasedAxis=us-gaap_CoalSupplyAgreementsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_LongTermPurchaseCommitmentByCategoryOfItemPurchasedAxis=lnt_LongTermPurchaseCommitmentsOtherMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: