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Debt (Tables) | 6 Months Ended
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Jun. 30, 2014
Debt Disclosure [Line Items] |
Other Short-Term Borrowings | 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 |  |  |  |
June 30, 2014 | (Consolidated) |  | Company |  | IPL |  | WPL
Commercial paper: |  |  |  |  |  |  |
Amount outstanding | $307.9 |  | $149.9 |  | $— |  | $158.0
Weighted average remaining maturity | 1 day |  | 1 day |  | N/A |  | 1 day
Weighted average interest rates | 0.2% |  | 0.2% |  | N/A |  | 0.1%
Available credit facility capacity | $692.1 |  | $150.1 |  | $300.0 |  | $242.0
| Alliant Energy |  | IPL |  | WPL
Three Months Ended June 30 | 2014 |  | 2013 |  | 2014 |  | 2013 |  | 2014 |  | 2013
Maximum amount outstanding (based on daily outstanding balances) |  | $311.6 |  |  |  | $223.1 |  |  |  | $6.0 |  |  |  | $6.0 |  |  |  | $168.4 |  |  |  | $159.4 |
Average amount outstanding (based on daily outstanding balances) |  | $262.7 |  |  |  | $191.4 |  |  |  | $0.1 |  |  |  | $0.2 |  |  |  | $141.8 |  |  |  | $125.7 |
Weighted average interest rates | 0.2 | % |  | 0.2 | % |  | 0.2 | % |  | 0.3 | % |  | 0.1 | % |  | 0.2 | %
Six Months Ended June 30 |  |  |  |  |  |  |  |  |  |  |
Maximum amount outstanding (based on daily outstanding balances) |  | $316.2 |  |  |  | $243.4 |  |  |  | $10.0 |  |  |  | $26.3 |  |  |  | $204.7 |  |  |  | $160.0 |
Average amount outstanding (based on daily outstanding balances) |  | $269.1 |  |  |  | $181.2 |  |  |  | $0.2 |  |  |  | $2.5 |  |  |  | $157.3 |  |  |  | $99.4 |
Weighted average interest rates | 0.2 | % |  | 0.3 | % |  | 0.2 | % |  | 0.4 | % |  | 0.1 | % |  | 0.2 | %
IPL [Member] |
Debt Disclosure [Line Items] |
Other Short-Term Borrowings | 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 |  |  |  |
June 30, 2014 | (Consolidated) |  | Company |  | IPL |  | WPL
Commercial paper: |  |  |  |  |  |  |
Amount outstanding | $307.9 |  | $149.9 |  | $— |  | $158.0
Weighted average remaining maturity | 1 day |  | 1 day |  | N/A |  | 1 day
Weighted average interest rates | 0.2% |  | 0.2% |  | N/A |  | 0.1%
Available credit facility capacity | $692.1 |  | $150.1 |  | $300.0 |  | $242.0
| Alliant Energy |  | IPL |  | WPL
Three Months Ended June 30 | 2014 |  | 2013 |  | 2014 |  | 2013 |  | 2014 |  | 2013
Maximum amount outstanding (based on daily outstanding balances) |  | $311.6 |  |  |  | $223.1 |  |  |  | $6.0 |  |  |  | $6.0 |  |  |  | $168.4 |  |  |  | $159.4 |
Average amount outstanding (based on daily outstanding balances) |  | $262.7 |  |  |  | $191.4 |  |  |  | $0.1 |  |  |  | $0.2 |  |  |  | $141.8 |  |  |  | $125.7 |
Weighted average interest rates | 0.2 | % |  | 0.2 | % |  | 0.2 | % |  | 0.3 | % |  | 0.1 | % |  | 0.2 | %
Six Months Ended June 30 |  |  |  |  |  |  |  |  |  |  |
Maximum amount outstanding (based on daily outstanding balances) |  | $316.2 |  |  |  | $243.4 |  |  |  | $10.0 |  |  |  | $26.3 |  |  |  | $204.7 |  |  |  | $160.0 |
Average amount outstanding (based on daily outstanding balances) |  | $269.1 |  |  |  | $181.2 |  |  |  | $0.2 |  |  |  | $2.5 |  |  |  | $157.3 |  |  |  | $99.4 |
Weighted average interest rates | 0.2 | % |  | 0.3 | % |  | 0.2 | % |  | 0.4 | % |  | 0.1 | % |  | 0.2 | %
WPL [Member] |
Debt Disclosure [Line Items] |
Other Short-Term Borrowings | 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 |  |  |  |
June 30, 2014 | (Consolidated) |  | Company |  | IPL |  | WPL
Commercial paper: |  |  |  |  |  |  |
Amount outstanding | $307.9 |  | $149.9 |  | $— |  | $158.0
Weighted average remaining maturity | 1 day |  | 1 day |  | N/A |  | 1 day
Weighted average interest rates | 0.2% |  | 0.2% |  | N/A |  | 0.1%
Available credit facility capacity | $692.1 |  | $150.1 |  | $300.0 |  | $242.0
| Alliant Energy |  | IPL |  | WPL
Three Months Ended June 30 | 2014 |  | 2013 |  | 2014 |  | 2013 |  | 2014 |  | 2013
Maximum amount outstanding (based on daily outstanding balances) |  | $311.6 |  |  |  | $223.1 |  |  |  | $6.0 |  |  |  | $6.0 |  |  |  | $168.4 |  |  |  | $159.4 |
Average amount outstanding (based on daily outstanding balances) |  | $262.7 |  |  |  | $191.4 |  |  |  | $0.1 |  |  |  | $0.2 |  |  |  | $141.8 |  |  |  | $125.7 |
Weighted average interest rates | 0.2 | % |  | 0.2 | % |  | 0.2 | % |  | 0.3 | % |  | 0.1 | % |  | 0.2 | %
Six Months Ended June 30 |  |  |  |  |  |  |  |  |  |  |
Maximum amount outstanding (based on daily outstanding balances) |  | $316.2 |  |  |  | $243.4 |  |  |  | $10.0 |  |  |  | $26.3 |  |  |  | $204.7 |  |  |  | $160.0 |
Average amount outstanding (based on daily outstanding balances) |  | $269.1 |  |  |  | $181.2 |  |  |  | $0.2 |  |  |  | $2.5 |  |  |  | $157.3 |  |  |  | $99.4 |
Weighted average interest rates | 0.2 | % |  | 0.3 | % |  | 0.2 | % |  | 0.4 | % |  | 0.1 | % |  | 0.2 | %

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- 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://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 19 -Article 5 Reference 2: 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) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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