XML 64 R41.htm IDEA: XBRL DOCUMENT
v3.7.0.1

Receivables (Narrative) (Details) - USD ($) $ in Millions | Mar. 31, 2017 | Dec. 31, 2016
--- | --- | ---
Receivables [Line Items] |  |  |
Deferred proceeds |  | $ 149.0 | $ 211.1
IPL [Member] |  |  |
Receivables [Line Items] |  |  |
Deferred proceeds |  | 149.0 | 211.1
Receivables Sold [Member] | IPL [Member] |  |  |
Receivables [Line Items] |  |  |
Receivables sold to third party |  | 221.0 | 248.1
Cash proceeds of receivables sold | [1] | 56.0 | 21.0
Deferred proceeds |  | 149.0 | $ 211.1
Available capacity |  | 41.8 |
Outstanding receivables past due |  | $ 69.9 |
[1] | Changes in cash proceeds are presented in “Sales of accounts receivable” in operating activities in Alliant Energy’s and IPL’s cash flows statements.

X
- Definition Cash Proceeds From Receivables Sold + References No definition available. + Details
Name: | lnt_CashProceedsFromReceivablesSold
Namespace Prefix: | lnt_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Fair value of deferred proceeds of receivables sold + References No definition available. + Details
Name: | lnt_FairValueOfDeferredProceedsOfReceivablesSold
Namespace Prefix: | lnt_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Outstanding receivables past due + References No definition available. + Details
Name: | lnt_OutstandingReceivablesPastDue
Namespace Prefix: | lnt_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Receivables sold + References No definition available. + Details
Name: | lnt_ReceivablesSold
Namespace Prefix: | lnt_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Sale of Accounts Receivable Program, Capacity Available + References No definition available. + Details
Name: | lnt_SaleofAccountsReceivableProgramCapacityAvailable
Namespace Prefix: | lnt_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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_AccountsNotesAndLoansReceivableLineItems
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: | us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis=lnt_ReceivablesSoldMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |