XML 49 R26.htm IDEA: XBRL DOCUMENT
v3.20.2

Debt (Tables) | 6 Months Ended
--- | ---
Jun. 30, 2020
Short-term Debt [Line Items] |
Other Short-Term Borrowings | Information regarding Alliant Energy’s, IPL’s and WPL’s commercial paper, and Alliant Energy’s and WPL’s borrowings under the single credit facility, which currently expires in August 2023, classified as short-term debt was as follows (dollars in millions):
June 30, 2020 | Alliant Energy |  | IPL |  | WPL
Amount outstanding | $185.4 |  | $— |  | $37.9
Weighted average interest rates | 0.3% |  | N/A |  | 0.2%
Available credit facility capacity | $814.6 |  | $250.0 |  | $262.1
| Alliant Energy |  | IPL |  | WPL
Three Months Ended June 30 | 2020 |  | 2019 |  | 2020 |  | 2019 |  | 2020 |  | 2019
Maximum amount outstanding (based on daily outstanding balances) | $270.5 |  | $590.2 |  | $8.4 |  | $— |  | $182.0 |  | $193.3
Average amount outstanding (based on daily outstanding balances) | $121.2 |  | $531.7 |  | $0.4 |  | $— |  | $8.7 |  | $141.6
Weighted average interest rates | 0.5% |  | 2.7% |  | 0.5% |  | N/A |  | 0.5% |  | 2.5%
Six Months Ended June 30 |  |  |  |  |  |  |  |  |  |  |
Maximum amount outstanding (based on daily outstanding balances) | $462.5 |  | $600.6 |  | $8.4 |  | $50.4 |  | $212.0 |  | $195.1
Average amount outstanding (based on daily outstanding balances) | $251.8 |  | $515.4 |  | $0.2 |  | $0.3 |  | $87.9 |  | $139.8
Weighted average interest rates | 1.5% |  | 2.7% |  | 0.5% |  | 2.8% |  | 1.7% |  | 2.5%
IPL [Member] |
Short-term Debt [Line Items] |
Other Short-Term Borrowings | Information regarding Alliant Energy’s, IPL’s and WPL’s commercial paper, and Alliant Energy’s and WPL’s borrowings under the single credit facility, which currently expires in August 2023, classified as short-term debt was as follows (dollars in millions):
June 30, 2020 | Alliant Energy |  | IPL |  | WPL
Amount outstanding | $185.4 |  | $— |  | $37.9
Weighted average interest rates | 0.3% |  | N/A |  | 0.2%
Available credit facility capacity | $814.6 |  | $250.0 |  | $262.1
| Alliant Energy |  | IPL |  | WPL
Three Months Ended June 30 | 2020 |  | 2019 |  | 2020 |  | 2019 |  | 2020 |  | 2019
Maximum amount outstanding (based on daily outstanding balances) | $270.5 |  | $590.2 |  | $8.4 |  | $— |  | $182.0 |  | $193.3
Average amount outstanding (based on daily outstanding balances) | $121.2 |  | $531.7 |  | $0.4 |  | $— |  | $8.7 |  | $141.6
Weighted average interest rates | 0.5% |  | 2.7% |  | 0.5% |  | N/A |  | 0.5% |  | 2.5%
Six Months Ended June 30 |  |  |  |  |  |  |  |  |  |  |
Maximum amount outstanding (based on daily outstanding balances) | $462.5 |  | $600.6 |  | $8.4 |  | $50.4 |  | $212.0 |  | $195.1
Average amount outstanding (based on daily outstanding balances) | $251.8 |  | $515.4 |  | $0.2 |  | $0.3 |  | $87.9 |  | $139.8
Weighted average interest rates | 1.5% |  | 2.7% |  | 0.5% |  | 2.8% |  | 1.7% |  | 2.5%
WPL [Member] |
Short-term Debt [Line Items] |
Other Short-Term Borrowings | Information regarding Alliant Energy’s, IPL’s and WPL’s commercial paper, and Alliant Energy’s and WPL’s borrowings under the single credit facility, which currently expires in August 2023, classified as short-term debt was as follows (dollars in millions):
June 30, 2020 | Alliant Energy |  | IPL |  | WPL
Amount outstanding | $185.4 |  | $— |  | $37.9
Weighted average interest rates | 0.3% |  | N/A |  | 0.2%
Available credit facility capacity | $814.6 |  | $250.0 |  | $262.1
| Alliant Energy |  | IPL |  | WPL
Three Months Ended June 30 | 2020 |  | 2019 |  | 2020 |  | 2019 |  | 2020 |  | 2019
Maximum amount outstanding (based on daily outstanding balances) | $270.5 |  | $590.2 |  | $8.4 |  | $— |  | $182.0 |  | $193.3
Average amount outstanding (based on daily outstanding balances) | $121.2 |  | $531.7 |  | $0.4 |  | $— |  | $8.7 |  | $141.6
Weighted average interest rates | 0.5% |  | 2.7% |  | 0.5% |  | N/A |  | 0.5% |  | 2.5%
Six Months Ended June 30 |  |  |  |  |  |  |  |  |  |  |
Maximum amount outstanding (based on daily outstanding balances) | $462.5 |  | $600.6 |  | $8.4 |  | $50.4 |  | $212.0 |  | $195.1
Average amount outstanding (based on daily outstanding balances) | $251.8 |  | $515.4 |  | $0.2 |  | $0.3 |  | $87.9 |  | $139.8
Weighted average interest rates | 1.5% |  | 2.7% |  | 0.5% |  | 2.8% |  | 1.7% |  | 2.5%

X
- Definition Tabular disclosure of short-term debt arrangements (having initial terms of repayment within one year or the normal operating cycle, if longer) including: (1) description of the short-term debt arrangement; (2) identification of the lender or type of lender; (3) repayment terms; (4) weighted average interest rate; (5) carrying amount of funds borrowed under the specified short-term debt arrangement as of the balance sheet date; (6) description of the refinancing of a short-term obligation when that obligation is excluded from current liabilities in the balance sheet; and (7) amount of a short-term obligation that has been excluded from current liabilities in the balance sheet because of a refinancing of the obligation. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.19) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_ScheduleOfShortTermDebtTextBlock
Namespace Prefix: | us-gaap_
Data Type: | nonnum: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_ShortTermDebtLineItems
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: |