Commitments And Contingencies (Other Purchase Commitments) (Details) $ in Millions	Dec. 31, 2022 USD ($)
Long-term Purchase Commitment [Line Items]
Minimum future commitments, 2023	$ 719
Minimum future commitments, 2024	373
Minimum future commitments, 2025	230
Minimum future commitments, 2026	148
Minimum future commitments, 2027	90
Minimum future commitments, Thereafter	233
Minimum future commitments, Total	1,793
Individual commitments incurred	1
Natural Gas [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments, 2023	558
Minimum future commitments, 2024	297
Minimum future commitments, 2025	199
Minimum future commitments, 2026	136
Minimum future commitments, 2027	85
Minimum future commitments, Thereafter	209
Minimum future commitments, Total	1,484
Coal [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments, 2023	89
Minimum future commitments, 2024	64
Minimum future commitments, 2025	22
Minimum future commitments, 2026	3
Minimum future commitments, 2027	3
Minimum future commitments, Thereafter	0
Minimum future commitments, Total	181
Other [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments, 2023	72
Minimum future commitments, 2024	12
Minimum future commitments, 2025	9
Minimum future commitments, 2026	9
Minimum future commitments, 2027	2
Minimum future commitments, Thereafter	24
Minimum future commitments, Total	128
IPL [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments, 2023	392
Minimum future commitments, 2024	195
Minimum future commitments, 2025	107
Minimum future commitments, 2026	53
Minimum future commitments, 2027	41
Minimum future commitments, Thereafter	61
Minimum future commitments, Total	849
IPL [Member] \| Natural Gas [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments, 2023	319
Minimum future commitments, 2024	167
Minimum future commitments, 2025	85
Minimum future commitments, 2026	48
Minimum future commitments, 2027	36
Minimum future commitments, Thereafter	39
Minimum future commitments, Total	694
IPL [Member] \| Coal [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments, 2023	45
Minimum future commitments, 2024	26
Minimum future commitments, 2025	20
Minimum future commitments, 2026	3
Minimum future commitments, 2027	3
Minimum future commitments, Thereafter	0
Minimum future commitments, Total	97
IPL [Member] \| Other [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments, 2023	28
Minimum future commitments, 2024	2
Minimum future commitments, 2025	2
Minimum future commitments, 2026	2
Minimum future commitments, 2027	2
Minimum future commitments, Thereafter	22
Minimum future commitments, Total	58
WPL [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments, 2023	311
Minimum future commitments, 2024	169
Minimum future commitments, 2025	117
Minimum future commitments, 2026	89
Minimum future commitments, 2027	49
Minimum future commitments, Thereafter	170
Minimum future commitments, Total	905
WPL [Member] \| Natural Gas [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments, 2023	239
Minimum future commitments, 2024	130
Minimum future commitments, 2025	114
Minimum future commitments, 2026	88
Minimum future commitments, 2027	49
Minimum future commitments, Thereafter	170
Minimum future commitments, Total	790
WPL [Member] \| Coal [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments, 2023	44
Minimum future commitments, 2024	38
Minimum future commitments, 2025	2
Minimum future commitments, 2026	0
Minimum future commitments, 2027	0
Minimum future commitments, Thereafter	0
Minimum future commitments, Total	84
WPL [Member] \| Other [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments, 2023	28
Minimum future commitments, 2024	1
Minimum future commitments, 2025	1
Minimum future commitments, 2026	1
Minimum future commitments, 2027	0
Minimum future commitments, Thereafter	0
Minimum future commitments, Total	$ 31

Individual commitments incurred in excess of $1 million

No definition available.

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

- 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

- Definition

Minimum amount of purchase arrangement in which the entity has agreed to expend funds to procure goods or services from a supplier.

+ References

No definition available.

+ Details

Name:	us-gaap_PurchaseObligation
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of purchase arrangement to be paid after fifth fiscal year following current fiscal year. Includes, but is not limited to, recorded and unrecorded purchase obligations, long-term purchase commitment, and short-term purchase commitment. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

No definition available.

+ Details

Name:	us-gaap_PurchaseObligationDueAfterFifthYear
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of purchase arrangement to be paid in fifth fiscal year following current fiscal year. Includes, but is not limited to, recorded and unrecorded purchase obligations, long-term purchase commitment, and short-term purchase commitment. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

No definition available.

+ Details

Name:	us-gaap_PurchaseObligationDueInFifthYear
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of purchase arrangement to be paid in fourth fiscal year following current fiscal year. Includes, but is not limited to, recorded and unrecorded purchase obligations, long-term purchase commitment, and short-term purchase commitment. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

No definition available.

+ Details

Name:	us-gaap_PurchaseObligationDueInFourthYear
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of purchase arrangement to be paid in next fiscal year following current fiscal year. Includes, but is not limited to, recorded and unrecorded purchase obligations, long-term purchase commitment, and short-term purchase commitment. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

No definition available.

+ Details

Name:	us-gaap_PurchaseObligationDueInNextTwelveMonths
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of purchase arrangement to be paid in second fiscal year following current fiscal year. Includes, but is not limited to, recorded and unrecorded purchase obligations, long-term purchase commitment, and short-term purchase commitment. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

No definition available.

+ Details

Name:	us-gaap_PurchaseObligationDueInSecondYear
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of purchase arrangement to be paid in third fiscal year following current fiscal year. Includes, but is not limited to, recorded and unrecorded purchase obligations, long-term purchase commitment, and short-term purchase commitment. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

No definition available.

+ Details

Name:	us-gaap_PurchaseObligationDueInThirdYear
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

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

- Details

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

- Details

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

- Details

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

- Details

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