XML 53 R33.htm IDEA: XBRL DOCUMENT
v3.21.1

Related Parties (Tables) | 3 Months Ended
--- | ---
Mar. 31, 2021
Related Party Transactions [Line Items] |
Services Provided, Sales Credited And Purchases | The amounts billed for services provided, sales credited and purchases for the three months ended March 31 were as follows (in millions):
| IPL |  | WPL
| 2021 |  | 2020 |  |  |  |  |  | 2021 |  | 2020 |  |  |  |
Corporate Services billings | $40 |  | $37 |  |  |  |  |  | $35 |  | $32 |  |  |  |
Sales credited | 1 |  | 15 |  |  |  |  |  | 1 |  | 2 |  |  |  |
Purchases billed | 143 |  | 81 |  |  |  |  |  | 26 |  | 20 |  |  |  |
Net Intercompany Payables | Net intercompany payables to Corporate Services were as follows (in millions):
| IPL |  | WPL
| March 31, 2021 |  | December 31, 2020 |  | March 31, 2021 |  | December 31, 2020
Net payables to Corporate Services | $73 |  | $110 |  | $60 |  | $73
Related Amounts Billed Between Parties | The related amounts billed between the parties for the three months ended March 31 were as follows (in millions):
| 2021 |  | 2020 |  |  |  |
ATC billings to WPL | $32 |  | $28 |  |  |  |
WPL billings to ATC | 3 |  | 3 |  |  |  |
IPL [Member] |
Related Party Transactions [Line Items] |
Services Provided, Sales Credited And Purchases | The amounts billed for services provided, sales credited and purchases for the three months ended March 31 were as follows (in millions):
| IPL |  | WPL
| 2021 |  | 2020 |  |  |  |  |  | 2021 |  | 2020 |  |  |  |
Corporate Services billings | $40 |  | $37 |  |  |  |  |  | $35 |  | $32 |  |  |  |
Sales credited | 1 |  | 15 |  |  |  |  |  | 1 |  | 2 |  |  |  |
Purchases billed | 143 |  | 81 |  |  |  |  |  | 26 |  | 20 |  |  |  |
Net Intercompany Payables | Net intercompany payables to Corporate Services were as follows (in millions):
| IPL |  | WPL
| March 31, 2021 |  | December 31, 2020 |  | March 31, 2021 |  | December 31, 2020
Net payables to Corporate Services | $73 |  | $110 |  | $60 |  | $73
WPL [Member] |
Related Party Transactions [Line Items] |
Services Provided, Sales Credited And Purchases | The amounts billed for services provided, sales credited and purchases for the three months ended March 31 were as follows (in millions):
| IPL |  | WPL
| 2021 |  | 2020 |  |  |  |  |  | 2021 |  | 2020 |  |  |  |
Corporate Services billings | $40 |  | $37 |  |  |  |  |  | $35 |  | $32 |  |  |  |
Sales credited | 1 |  | 15 |  |  |  |  |  | 1 |  | 2 |  |  |  |
Purchases billed | 143 |  | 81 |  |  |  |  |  | 26 |  | 20 |  |  |  |
Net Intercompany Payables | Net intercompany payables to Corporate Services were as follows (in millions):
| IPL |  | WPL
| March 31, 2021 |  | December 31, 2020 |  | March 31, 2021 |  | December 31, 2020
Net payables to Corporate Services | $73 |  | $110 |  | $60 |  | $73
Related Amounts Billed Between Parties | The related amounts billed between the parties for the three months ended March 31 were as follows (in millions):
| 2021 |  | 2020 |  |  |  |
ATC billings to WPL | $32 |  | $28 |  |  |  |
WPL billings to ATC | 3 |  | 3 |  |  |  |

X
- Definition Schedule of amounts billed for ATC (Table Text Block) + References No definition available. + Details
Name: | lnt_ScheduleOfAtcBillingsTableTextBlock
Namespace Prefix: | lnt_
Data Type: | dtr-types:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Schedule of Corporate Services Intercompany Payables (Table Text Block). + References No definition available. + Details
Name: | lnt_ScheduleOfCorporateServicesIntercompanyPayablesTableTextBlock
Namespace Prefix: | lnt_
Data Type: | dtr-types:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Schedule of System Coordination and Operating Agreement Schedule of Sales Credited and Purchases Billed (Table Text Block) + References No definition available. + Details
Name: | lnt_ScheduleOfScoaSalesCreditedAndPurchasesBilledTableTextBlock
Namespace Prefix: | lnt_
Data Type: | dtr-types:textBlockItemType
Balance Type: | na
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_RelatedPartyTransactionLineItems
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: |