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Debt | 3 Months Ended
--- | ---
Mar. 31, 2015
Debt [Line Items] |
Debt | DEBT Short-term Debt - Information regarding commercial paper classified as short-term debt and back-stopped by the credit facilities was as follows (dollars in millions):
| Alliant Energy |  | Parent |  |  |  |
March 31, 2015 | (Consolidated) |  | Company |  | IPL |  | WPL
Commercial paper: |  |  |  |  |  |  |
Amount outstanding | $41.5 |  | $41.5 |  | $— |  | $—
Weighted average remaining maturity | 1 day |  | 1 day |  | N/A |  | N/A
Weighted average interest rates | 0.5% |  | 0.5% |  | N/A |  | N/A
Available credit facility capacity | $958.5 |  | $258.5 |  | $300.0 |  | $400.0
| Alliant Energy |  | IPL |  | WPL
Three Months Ended March 31 | 2015 |  | 2014 |  | 2015 |  | 2014 |  | 2015 |  | 2014
Maximum amount outstanding (based on daily outstanding balances) |  | $151.3 |  |  |  | $316.2 |  |  |  | $1.4 |  |  |  | $10.0 |  |  |  | $— |  |  |  | $204.7 |
Average amount outstanding (based on daily outstanding balances) |  | $127.9 |  |  |  | $275.6 |  |  |  | $— |  |  |  | $0.3 |  |  |  | $— |  |  |  | $173.0 |
Weighted average interest rates | 0.4 | % |  | 0.1 | % |  | 0.4 | % |  | 0.2 | % |  | N/A |  |  | 0.1 | %
IPL [Member] |
Debt [Line Items] |
Debt | DEBT Short-term Debt - Information regarding commercial paper classified as short-term debt and back-stopped by the credit facilities was as follows (dollars in millions):
| Alliant Energy |  | Parent |  |  |  |
March 31, 2015 | (Consolidated) |  | Company |  | IPL |  | WPL
Commercial paper: |  |  |  |  |  |  |
Amount outstanding | $41.5 |  | $41.5 |  | $— |  | $—
Weighted average remaining maturity | 1 day |  | 1 day |  | N/A |  | N/A
Weighted average interest rates | 0.5% |  | 0.5% |  | N/A |  | N/A
Available credit facility capacity | $958.5 |  | $258.5 |  | $300.0 |  | $400.0
| Alliant Energy |  | IPL |  | WPL
Three Months Ended March 31 | 2015 |  | 2014 |  | 2015 |  | 2014 |  | 2015 |  | 2014
Maximum amount outstanding (based on daily outstanding balances) |  | $151.3 |  |  |  | $316.2 |  |  |  | $1.4 |  |  |  | $10.0 |  |  |  | $— |  |  |  | $204.7 |
Average amount outstanding (based on daily outstanding balances) |  | $127.9 |  |  |  | $275.6 |  |  |  | $— |  |  |  | $0.3 |  |  |  | $— |  |  |  | $173.0 |
Weighted average interest rates | 0.4 | % |  | 0.1 | % |  | 0.4 | % |  | 0.2 | % |  | N/A |  |  | 0.1 | %
WPL [Member] |
Debt [Line Items] |
Debt | DEBT Short-term Debt - Information regarding commercial paper classified as short-term debt and back-stopped by the credit facilities was as follows (dollars in millions):
| Alliant Energy |  | Parent |  |  |  |
March 31, 2015 | (Consolidated) |  | Company |  | IPL |  | WPL
Commercial paper: |  |  |  |  |  |  |
Amount outstanding | $41.5 |  | $41.5 |  | $— |  | $—
Weighted average remaining maturity | 1 day |  | 1 day |  | N/A |  | N/A
Weighted average interest rates | 0.5% |  | 0.5% |  | N/A |  | N/A
Available credit facility capacity | $958.5 |  | $258.5 |  | $300.0 |  | $400.0
| Alliant Energy |  | IPL |  | WPL
Three Months Ended March 31 | 2015 |  | 2014 |  | 2015 |  | 2014 |  | 2015 |  | 2014
Maximum amount outstanding (based on daily outstanding balances) |  | $151.3 |  |  |  | $316.2 |  |  |  | $1.4 |  |  |  | $10.0 |  |  |  | $— |  |  |  | $204.7 |
Average amount outstanding (based on daily outstanding balances) |  | $127.9 |  |  |  | $275.6 |  |  |  | $— |  |  |  | $0.3 |  |  |  | $— |  |  |  | $173.0 |
Weighted average interest rates | 0.4 | % |  | 0.1 | % |  | 0.4 | % |  | 0.2 | % |  | N/A |  |  | 0.1 | %

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- Definition The entire disclosure for information about short-term and long-term debt arrangements, which includes amounts of borrowings under each line of credit, note payable, commercial paper issue, bonds indenture, debenture issue, own-share lending arrangements and any other contractual agreement to repay funds, and about the underlying arrangements, rationale for a classification as long-term, including repayment terms, interest rates, collateral provided, restrictions on use of assets and activities, whether or not in compliance with debt covenants, and other matters important to users of the financial statements, such as the effects of refinancing and noncompliance with debt covenants. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21475-112644 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 19, 20, 22 -Article 5 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.19,20,22) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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