XML 66 R47.htm IDEA: XBRL DOCUMENT
v3.23.2

Common Equity (Narrative) (Details) - USD ($) $ in Millions | 1 Months Ended | 3 Months Ended | 6 Months Ended | 12 Months Ended
--- | --- | --- | --- | ---
Jul. 31, 2023 | Jun. 30, 2023 | Jun. 30, 2022 | Jun. 30, 2023 | Jun. 30, 2022 | Dec. 31, 2023
Common Equity [Line Items] |  |  |  |  |  |
Proceeds from issuance of common stock, net |  | $ 70 | $ 6 | $ 76 | $ 13 |
Common stock issued during period, At-the-market offering program (in shares) |  |  |  | 134,334 |  |
At The Market Offering Program |  |  |  |  |  |
Common Equity [Line Items] |  |  |  |  |  |
Proceeds from issuance of common stock, net |  |  |  | $ 64 |  |
Fees and commissions from issuance of common stock |  |  |  | $ 1 |  |
Common stock issued during period, At-the-market offering program (in shares) |  |  |  | 1,221,775 |  |
At The Market Offering Program | Subsequent Event [Member] |  |  |  |  |  |
Common Equity [Line Items] |  |  |  |  |  |
Proceeds from issuance of common stock, net | $ 9 |  |  |  |  |
Common stock issued during period, At-the-market offering program (in shares) | 172,701 |  |  |  |  |
At The Market Offering Program | Forecast [Member] |  |  |  |  |  |
Common Equity [Line Items] |  |  |  |  |  |
Maximum aggregate gross sales price of common stock that can be offered and sold |  |  |  |  |  | $ 225

X
- Definition Common Equity [Line Items] + References No definition available. + Details
Name: | lnt_CommonEquityLineItems
Namespace Prefix: | lnt_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Fees And Commissions From Issuance Of Common Stock [Member] + References No definition available. + Details
Name: | lnt_FeesAndCommissionsFromIssuanceOfCommonStock
Namespace Prefix: | lnt_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Maximum Aggregate Gross Sales Price Of Common Stock That Can Be Offered And Sold [Member] + References No definition available. + Details
Name: | lnt_MaximumAggregateGrossSalesPriceOfCommonStockThatCanBeOfferedAndSold
Namespace Prefix: | lnt_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The cash inflow from the additional capital contribution to the entity. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 45 -Paragraph 14 -Subparagraph (a) -SubTopic 10 -Topic 230 -Publisher FASB -URI https://asc.fasb.org//1943274/2147482740/230-10-45-14 + Details
Name: | us-gaap_ProceedsFromIssuanceOfCommonStock
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Number of shares issued during the period as a result of an employee stock purchase plan. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 50 -Paragraph 2 -SubTopic 10 -Topic 505 -Publisher FASB -URI https://asc.fasb.org//1943274/2147481112/505-10-50-2 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 210 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(28)) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480566/210-10-S99-1 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 505 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.3-04) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480008/505-10-S99-1 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 210 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(29)) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480566/210-10-S99-1 + Details
Name: | us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_SubsidiarySaleOfStockAxis=lnt_AtTheMarketOfferingProgramMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_StatementScenarioAxis=srt_ScenarioForecastMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |