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Debt | 12 Months Ended
--- | ---
Dec. 31, 2013
Debt Instrument [Line Items] |
Debt | DEBT (a) Short-term Debt - Alliant Energy and its subsidiaries maintain committed bank lines of credit to provide short-term borrowing flexibility and back-stop liquidity for commercial paper outstanding. At December 31, 2013, Alliant Energy’s short-term borrowing arrangements included three revolving credit facilities totaling $1 billion ($300 million for Alliant Energy at the parent company level, $300 million for IPL and $400 million for WPL), which expire in December 2017. Information regarding commercial paper classified as short-term debt and back-stopped by the credit facilities was as follows (dollars in millions):
| Alliant Energy |  | IPL |  | WPL
| 2013 |  | 2012 |  | 2013 |  | 2012 |  | 2013 |  | 2012
December 31 |  |  |  |  |  |  |  |  |  |  |
Commercial paper: |  |  |  |  |  |  |  |  |  |  |
Amount outstanding | $279.4 |  | $217.5 |  | $— |  | $26.3 |  | $183.7 |  | $86.6
Weighted average interest rates | 0.2% |  | 0.4% |  | N/A |  | 0.4% |  | 0.1% |  | 0.3%
Weighted average remaining maturity | 4 days |  | 11 days |  | N/A |  | 2 days |  | 6 days |  | 19 days
Available credit facility capacity (a) | $720.6 |  | $732.5 |  | $300.0 |  | $223.7 |  | $216.3 |  | $313.4
| Alliant Energy |  | IPL |  | WPL
| 2013 |  | 2012 |  | 2013 |  | 2012 |  | 2013 |  | 2012
For the year ended |  |  |  |  |  |  |  |  |  |  |
Maximum amount outstanding (based on daily outstanding balances) | $293.9 |  | $217.5 |  | $26.3 |  | $35.4 |  | $190.0 |  | $86.6
Average amount outstanding (based on daily outstanding balances) | $210.5 |  | $99.8 |  | $1.3 |  | $5.9 |  | $123.5 |  | $11.7
Weighted average interest rates | 0.2% |  | 0.4% |  | 0.4% |  | 0.4% |  | 0.2% |  | 0.3%
(a) | At December 31, 2012, Alliant Energy’s and IPL’s available credit facility capacities reflect outstanding commercial paper classified as both short- and long-term debt. Refer to Note 9(b) for further discussion of $50.0 million of commercial paper outstanding at December 31, 2012 classified as long-term debt on Alliant Energy’s and IPL’s Consolidated Balance Sheets. Alliant Energy and its subsidiaries did not have any commercial paper classified as long-term debt as of December 31, 2013.
Alliant Energy’s, IPL’s and WPL’s credit facility agreements each contain a financial covenant, which requires the entities to maintain certain debt-to-capital ratios in order to borrow under the credit facilities. The required debt-to-capital ratios compared to the actual debt-to-capital ratios at December 31, 2013 were as follows:
| Alliant Energy |  | IPL |  | WPL
Requirement | Less than 65% |  | Less than 58% |  | Less than 58%
Actual | 51% |  | 45% |  | 50%
The debt component of the capital ratios includes long- and short-term debt (excluding non-recourse debt and hybrid securities to the extent the total carrying value of such hybrid securities does not exceed 15% of consolidated capital of the applicable borrower), capital lease obligations, certain letters of credit, guarantees of the foregoing and new synthetic leases. Unfunded vested benefits under qualified pension plans are not included in the debt-to-capital ratios. The equity component of the capital ratios excludes accumulated other comprehensive income (loss). (b) Long-Term Debt - Long-term debt, net as of December 31 was as follows (dollars in millions):
| 2013 |  | 2012
| Alliant Energy |  | IPL |  | WPL |  | Alliant Energy |  | IPL |  | WPL
Senior Debentures: |  |  |  |  |  |  |  |  |  |  |
3.3%, due 2015 |  | $150.0 |  |  |  | $150.0 |  |  |  | $— |  |  |  | $150.0 |  |  |  | $150.0 |  |  |  | $— |
5.875%, due 2018 | 100.0 |  |  | 100.0 |  |  | — |  |  | 100.0 |  |  | 100.0 |  |  | — |
7.25%, due 2018 | 250.0 |  |  | 250.0 |  |  | — |  |  | 250.0 |  |  | 250.0 |  |  | — |
3.65%, due 2020 | 200.0 |  |  | 200.0 |  |  | — |  |  | 200.0 |  |  | 200.0 |  |  | — |
5.5%, due 2025 | 50.0 |  |  | 50.0 |  |  | — |  |  | 50.0 |  |  | 50.0 |  |  | — |
6.45%, due 2033 | 100.0 |  |  | 100.0 |  |  | — |  |  | 100.0 |  |  | 100.0 |  |  | — |
6.3%, due 2034 | 125.0 |  |  | 125.0 |  |  | — |  |  | 125.0 |  |  | 125.0 |  |  | — |
6.25%, due 2039 | 300.0 |  |  | 300.0 |  |  | — |  |  | 300.0 |  |  | 300.0 |  |  | — |
4.7%, due 2043 (a) | 250.0 |  |  | 250.0 |  |  | — |  |  | — |  |  | — |  |  | — |
| 1,525.0 |  |  | 1,525.0 |  |  | — |  |  | 1,275.0 |  |  | 1,275.0 |  |  | — |
Debentures: |  |  |  |  |  |  |  |  |  |  |
5%, due 2019 | 250.0 |  |  | — |  |  | 250.0 |  |  | 250.0 |  |  | — |  |  | 250.0 |
4.6%, due 2020 | 150.0 |  |  | — |  |  | 150.0 |  |  | 150.0 |  |  | — |  |  | 150.0 |
2.25%, due 2022 | 250.0 |  |  | — |  |  | 250.0 |  |  | 250.0 |  |  | — |  |  | 250.0 |
6.25%, due 2034 | 100.0 |  |  | — |  |  | 100.0 |  |  | 100.0 |  |  | — |  |  | 100.0 |
6.375%, due 2037 | 300.0 |  |  | — |  |  | 300.0 |  |  | 300.0 |  |  | — |  |  | 300.0 |
7.6%, due 2038 | 250.0 |  |  | — |  |  | 250.0 |  |  | 250.0 |  |  | — |  |  | 250.0 |
| 1,300.0 |  |  | — |  |  | 1,300.0 |  |  | 1,300.0 |  |  | — |  |  | 1,300.0 |
Pollution Control Revenue Bonds: |  |  |  |  |  |  |  |  |  |  |
5%, due 2014 | 38.4 |  |  | 38.4 |  |  | — |  |  | 38.4 |  |  | 38.4 |  |  | — |
5%, due 2014 and 2015 | 24.5 |  |  | — |  |  | 24.5 |  |  | 24.5 |  |  | — |  |  | 24.5 |
5.375%, due 2015 | 14.6 |  |  | — |  |  | 14.6 |  |  | 14.6 |  |  | — |  |  | 14.6 |
| 77.5 |  |  | 38.4 |  |  | 39.1 |  |  | 77.5 |  |  | 38.4 |  |  | 39.1 |
Other: |  |  |  |  |  |  |  |  |  |  |
Commercial paper, 0.4% at December 31, 2012 (b) | — |  |  | — |  |  | — |  |  | 50.0 |  |  | 50.0 |  |  | — |
4% senior notes, due 2014 | 250.0 |  |  | — |  |  | — |  |  | 250.0 |  |  | — |  |  | — |
Term loan credit agreement through 2014, 1% at December 31, 2013 | 60.0 |  |  | — |  |  | — |  |  | 60.0 |  |  | — |  |  | — |
3.45% senior notes, due 2022 | 75.0 |  |  | — |  |  | — |  |  | 75.0 |  |  | — |  |  | — |
5.06% senior secured notes, due 2014 to 2024 | 60.5 |  |  | — |  |  | — |  |  | 61.9 |  |  | — |  |  | — |
Other, 1% at December 31, 2013, due 2014 to 2025 | 0.4 |  |  | — |  |  | — |  |  | 0.5 |  |  | — |  |  | — |
| 445.9 |  |  | — |  |  | — |  |  | 497.4 |  |  | 50.0 |  |  | — |
Subtotal | 3,348.4 |  |  | 1,563.4 |  |  | 1,339.1 |  |  | 3,149.9 |  |  | 1,363.4 |  |  | 1,339.1 |
Current maturities | (358.5 | ) |  | (38.4 | ) |  | (8.5 | ) |  | (1.5 | ) |  | — |  |  | — |
Unamortized debt (discount) and premium, net | (12.1 | ) |  | (5.0 | ) |  | (7.0 | ) |  | (11.8 | ) |  | (3.9 | ) |  | (7.6 | )
Long-term debt, net |  | $2,977.8 |  |  |  | $1,520.0 |  |  |  | $1,323.6 |  |  |  | $3,136.6 |  |  |  | $1,359.5 |  |  |  | $1,331.5 |
(a) | In 2013, IPL issued $250.0 million of 4.7% senior debentures due 2043. The proceeds from the issuance were used by IPL to reduce cash proceeds received from its sales of accounts receivable program, reduce commercial paper classified as long-term debt by $65 million and for general working capital purposes.
(b) | At December 31, 2012, $50.0 million of commercial paper was recorded in “Long-term debt, net” on Alliant Energy’s and IPL’s Consolidated Balance Sheets due to the existence of long-term credit facilities that back-stop this commercial paper balance, along with Alliant Energy’s and IPL’s intent and ability to refinance these balances on a long-term basis.
Five-Year Schedule of Debt Maturities - At December 31, 2013, debt maturities for 2014 to 2018 were as follows (in millions):
| 2014 |  | 2015 |  | 2016 |  | 2017 |  | 2018
IPL |  | $38 |  |  |  | $150 |  |  |  | $— |  |  |  | $— |  |  |  | $350 |
WPL | 9 |  |  | 31 |  |  | — |  |  | — |  |  | — |
Resources | 62 |  |  | 2 |  |  | 3 |  |  | 4 |  |  | 5 |
Alliant Energy parent company | 250 |  |  | — |  |  | — |  |  | — |  |  | — |
Alliant Energy |  | $359 |  |  |  | $183 |  |  |  | $3 |  |  |  | $4 |  |  |  | $355 |
At December 31, 2013, there were no significant sinking fund requirements related to the long-term debt on the Consolidated Balance Sheets. Indentures - Alliant Energy maintains an indenture related to its 4% senior notes due 2014. IPL maintains an indenture related to its senior debentures due 2015 through 2043. WPL maintains an indenture related to its debentures due 2019 through 2038. Sheboygan Power, Resources’ wholly-owned subsidiary, maintains an indenture related to the issuance of its 5.06% senior secured notes due 2014 to 2024. Optional Redemption Provisions - Alliant Energy and its subsidiaries have certain issuances of long-term debt that contain optional redemption provisions which, if elected by the issuer at its sole discretion, could require material redemption premium payments by the issuer. The redemption premium payments under these optional redemption provisions are variable and dependent on applicable U.S. Treasury rates at the time of redemption. At December 31, 2013, the debt issuances that contained these optional redemption provisions included all of IPL’s outstanding senior debentures, all of WPL’s outstanding debentures, Alliant Energy’s senior notes due 2014, Corporate Services’ senior notes due 2022 and Sheboygan Power’s senior secured notes due 2014 to 2024. Security Provisions - Sheboygan Power’s 5.06% senior secured notes due 2014 to 2024 are secured by Sheboygan Falls and related assets. Unamortized Debt Issuance Costs - Unamortized debt issuance costs recorded in “Deferred charges and other” on the Consolidated Balance Sheets at December 31 were as follows (in millions):
| Alliant Energy |  | IPL |  | WPL
| 2013 |  | 2012 |  | 2013 |  | 2012 |  | 2013 |  | 2012
Unamortized debt issuance costs | $19.9 |  | $19.5 |  | $9.7 |  | $8.0 |  | $9.0 |  | $9.8
Carrying Amount and Fair Value of Long-term Debt - Refer to Note 14 for information on the carrying amount and fair value of long-term debt outstanding at December 31, 2013 and 2012.
IPL [Member] |
Debt Instrument [Line Items] |
Debt | DEBT (a) Short-term Debt - Alliant Energy and its subsidiaries maintain committed bank lines of credit to provide short-term borrowing flexibility and back-stop liquidity for commercial paper outstanding. At December 31, 2013, Alliant Energy’s short-term borrowing arrangements included three revolving credit facilities totaling $1 billion ($300 million for Alliant Energy at the parent company level, $300 million for IPL and $400 million for WPL), which expire in December 2017. Information regarding commercial paper classified as short-term debt and back-stopped by the credit facilities was as follows (dollars in millions):
| Alliant Energy |  | IPL |  | WPL
| 2013 |  | 2012 |  | 2013 |  | 2012 |  | 2013 |  | 2012
December 31 |  |  |  |  |  |  |  |  |  |  |
Commercial paper: |  |  |  |  |  |  |  |  |  |  |
Amount outstanding | $279.4 |  | $217.5 |  | $— |  | $26.3 |  | $183.7 |  | $86.6
Weighted average interest rates | 0.2% |  | 0.4% |  | N/A |  | 0.4% |  | 0.1% |  | 0.3%
Weighted average remaining maturity | 4 days |  | 11 days |  | N/A |  | 2 days |  | 6 days |  | 19 days
Available credit facility capacity (a) | $720.6 |  | $732.5 |  | $300.0 |  | $223.7 |  | $216.3 |  | $313.4
| Alliant Energy |  | IPL |  | WPL
| 2013 |  | 2012 |  | 2013 |  | 2012 |  | 2013 |  | 2012
For the year ended |  |  |  |  |  |  |  |  |  |  |
Maximum amount outstanding (based on daily outstanding balances) | $293.9 |  | $217.5 |  | $26.3 |  | $35.4 |  | $190.0 |  | $86.6
Average amount outstanding (based on daily outstanding balances) | $210.5 |  | $99.8 |  | $1.3 |  | $5.9 |  | $123.5 |  | $11.7
Weighted average interest rates | 0.2% |  | 0.4% |  | 0.4% |  | 0.4% |  | 0.2% |  | 0.3%
(a) | At December 31, 2012, Alliant Energy’s and IPL’s available credit facility capacities reflect outstanding commercial paper classified as both short- and long-term debt. Refer to Note 9(b) for further discussion of $50.0 million of commercial paper outstanding at December 31, 2012 classified as long-term debt on Alliant Energy’s and IPL’s Consolidated Balance Sheets. Alliant Energy and its subsidiaries did not have any commercial paper classified as long-term debt as of December 31, 2013.
Alliant Energy’s, IPL’s and WPL’s credit facility agreements each contain a financial covenant, which requires the entities to maintain certain debt-to-capital ratios in order to borrow under the credit facilities. The required debt-to-capital ratios compared to the actual debt-to-capital ratios at December 31, 2013 were as follows:
| Alliant Energy |  | IPL |  | WPL
Requirement | Less than 65% |  | Less than 58% |  | Less than 58%
Actual | 51% |  | 45% |  | 50%
The debt component of the capital ratios includes long- and short-term debt (excluding non-recourse debt and hybrid securities to the extent the total carrying value of such hybrid securities does not exceed 15% of consolidated capital of the applicable borrower), capital lease obligations, certain letters of credit, guarantees of the foregoing and new synthetic leases. Unfunded vested benefits under qualified pension plans are not included in the debt-to-capital ratios. The equity component of the capital ratios excludes accumulated other comprehensive income (loss). (b) Long-Term Debt - Long-term debt, net as of December 31 was as follows (dollars in millions):
| 2013 |  | 2012
| Alliant Energy |  | IPL |  | WPL |  | Alliant Energy |  | IPL |  | WPL
Senior Debentures: |  |  |  |  |  |  |  |  |  |  |
3.3%, due 2015 |  | $150.0 |  |  |  | $150.0 |  |  |  | $— |  |  |  | $150.0 |  |  |  | $150.0 |  |  |  | $— |
5.875%, due 2018 | 100.0 |  |  | 100.0 |  |  | — |  |  | 100.0 |  |  | 100.0 |  |  | — |
7.25%, due 2018 | 250.0 |  |  | 250.0 |  |  | — |  |  | 250.0 |  |  | 250.0 |  |  | — |
3.65%, due 2020 | 200.0 |  |  | 200.0 |  |  | — |  |  | 200.0 |  |  | 200.0 |  |  | — |
5.5%, due 2025 | 50.0 |  |  | 50.0 |  |  | — |  |  | 50.0 |  |  | 50.0 |  |  | — |
6.45%, due 2033 | 100.0 |  |  | 100.0 |  |  | — |  |  | 100.0 |  |  | 100.0 |  |  | — |
6.3%, due 2034 | 125.0 |  |  | 125.0 |  |  | — |  |  | 125.0 |  |  | 125.0 |  |  | — |
6.25%, due 2039 | 300.0 |  |  | 300.0 |  |  | — |  |  | 300.0 |  |  | 300.0 |  |  | — |
4.7%, due 2043 (a) | 250.0 |  |  | 250.0 |  |  | — |  |  | — |  |  | — |  |  | — |
| 1,525.0 |  |  | 1,525.0 |  |  | — |  |  | 1,275.0 |  |  | 1,275.0 |  |  | — |
Debentures: |  |  |  |  |  |  |  |  |  |  |
5%, due 2019 | 250.0 |  |  | — |  |  | 250.0 |  |  | 250.0 |  |  | — |  |  | 250.0 |
4.6%, due 2020 | 150.0 |  |  | — |  |  | 150.0 |  |  | 150.0 |  |  | — |  |  | 150.0 |
2.25%, due 2022 | 250.0 |  |  | — |  |  | 250.0 |  |  | 250.0 |  |  | — |  |  | 250.0 |
6.25%, due 2034 | 100.0 |  |  | — |  |  | 100.0 |  |  | 100.0 |  |  | — |  |  | 100.0 |
6.375%, due 2037 | 300.0 |  |  | — |  |  | 300.0 |  |  | 300.0 |  |  | — |  |  | 300.0 |
7.6%, due 2038 | 250.0 |  |  | — |  |  | 250.0 |  |  | 250.0 |  |  | — |  |  | 250.0 |
| 1,300.0 |  |  | — |  |  | 1,300.0 |  |  | 1,300.0 |  |  | — |  |  | 1,300.0 |
Pollution Control Revenue Bonds: |  |  |  |  |  |  |  |  |  |  |
5%, due 2014 | 38.4 |  |  | 38.4 |  |  | — |  |  | 38.4 |  |  | 38.4 |  |  | — |
5%, due 2014 and 2015 | 24.5 |  |  | — |  |  | 24.5 |  |  | 24.5 |  |  | — |  |  | 24.5 |
5.375%, due 2015 | 14.6 |  |  | — |  |  | 14.6 |  |  | 14.6 |  |  | — |  |  | 14.6 |
| 77.5 |  |  | 38.4 |  |  | 39.1 |  |  | 77.5 |  |  | 38.4 |  |  | 39.1 |
Other: |  |  |  |  |  |  |  |  |  |  |
Commercial paper, 0.4% at December 31, 2012 (b) | — |  |  | — |  |  | — |  |  | 50.0 |  |  | 50.0 |  |  | — |
4% senior notes, due 2014 | 250.0 |  |  | — |  |  | — |  |  | 250.0 |  |  | — |  |  | — |
Term loan credit agreement through 2014, 1% at December 31, 2013 | 60.0 |  |  | — |  |  | — |  |  | 60.0 |  |  | — |  |  | — |
3.45% senior notes, due 2022 | 75.0 |  |  | — |  |  | — |  |  | 75.0 |  |  | — |  |  | — |
5.06% senior secured notes, due 2014 to 2024 | 60.5 |  |  | — |  |  | — |  |  | 61.9 |  |  | — |  |  | — |
Other, 1% at December 31, 2013, due 2014 to 2025 | 0.4 |  |  | — |  |  | — |  |  | 0.5 |  |  | — |  |  | — |
| 445.9 |  |  | — |  |  | — |  |  | 497.4 |  |  | 50.0 |  |  | — |
Subtotal | 3,348.4 |  |  | 1,563.4 |  |  | 1,339.1 |  |  | 3,149.9 |  |  | 1,363.4 |  |  | 1,339.1 |
Current maturities | (358.5 | ) |  | (38.4 | ) |  | (8.5 | ) |  | (1.5 | ) |  | — |  |  | — |
Unamortized debt (discount) and premium, net | (12.1 | ) |  | (5.0 | ) |  | (7.0 | ) |  | (11.8 | ) |  | (3.9 | ) |  | (7.6 | )
Long-term debt, net |  | $2,977.8 |  |  |  | $1,520.0 |  |  |  | $1,323.6 |  |  |  | $3,136.6 |  |  |  | $1,359.5 |  |  |  | $1,331.5 |
(a) | In 2013, IPL issued $250.0 million of 4.7% senior debentures due 2043. The proceeds from the issuance were used by IPL to reduce cash proceeds received from its sales of accounts receivable program, reduce commercial paper classified as long-term debt by $65 million and for general working capital purposes.
(b) | At December 31, 2012, $50.0 million of commercial paper was recorded in “Long-term debt, net” on Alliant Energy’s and IPL’s Consolidated Balance Sheets due to the existence of long-term credit facilities that back-stop this commercial paper balance, along with Alliant Energy’s and IPL’s intent and ability to refinance these balances on a long-term basis.
Five-Year Schedule of Debt Maturities - At December 31, 2013, debt maturities for 2014 to 2018 were as follows (in millions):
| 2014 |  | 2015 |  | 2016 |  | 2017 |  | 2018
IPL |  | $38 |  |  |  | $150 |  |  |  | $— |  |  |  | $— |  |  |  | $350 |
WPL | 9 |  |  | 31 |  |  | — |  |  | — |  |  | — |
Resources | 62 |  |  | 2 |  |  | 3 |  |  | 4 |  |  | 5 |
Alliant Energy parent company | 250 |  |  | — |  |  | — |  |  | — |  |  | — |
Alliant Energy |  | $359 |  |  |  | $183 |  |  |  | $3 |  |  |  | $4 |  |  |  | $355 |
At December 31, 2013, there were no significant sinking fund requirements related to the long-term debt on the Consolidated Balance Sheets. Indentures - Alliant Energy maintains an indenture related to its 4% senior notes due 2014. IPL maintains an indenture related to its senior debentures due 2015 through 2043. WPL maintains an indenture related to its debentures due 2019 through 2038. Sheboygan Power, Resources’ wholly-owned subsidiary, maintains an indenture related to the issuance of its 5.06% senior secured notes due 2014 to 2024. Optional Redemption Provisions - Alliant Energy and its subsidiaries have certain issuances of long-term debt that contain optional redemption provisions which, if elected by the issuer at its sole discretion, could require material redemption premium payments by the issuer. The redemption premium payments under these optional redemption provisions are variable and dependent on applicable U.S. Treasury rates at the time of redemption. At December 31, 2013, the debt issuances that contained these optional redemption provisions included all of IPL’s outstanding senior debentures, all of WPL’s outstanding debentures, Alliant Energy’s senior notes due 2014, Corporate Services’ senior notes due 2022 and Sheboygan Power’s senior secured notes due 2014 to 2024. Security Provisions - Sheboygan Power’s 5.06% senior secured notes due 2014 to 2024 are secured by Sheboygan Falls and related assets. Unamortized Debt Issuance Costs - Unamortized debt issuance costs recorded in “Deferred charges and other” on the Consolidated Balance Sheets at December 31 were as follows (in millions):
| Alliant Energy |  | IPL |  | WPL
| 2013 |  | 2012 |  | 2013 |  | 2012 |  | 2013 |  | 2012
Unamortized debt issuance costs | $19.9 |  | $19.5 |  | $9.7 |  | $8.0 |  | $9.0 |  | $9.8
Carrying Amount and Fair Value of Long-term Debt - Refer to Note 14 for information on the carrying amount and fair value of long-term debt outstanding at December 31, 2013 and 2012.
WPL [Member] |
Debt Instrument [Line Items] |
Debt | DEBT (a) Short-term Debt - Alliant Energy and its subsidiaries maintain committed bank lines of credit to provide short-term borrowing flexibility and back-stop liquidity for commercial paper outstanding. At December 31, 2013, Alliant Energy’s short-term borrowing arrangements included three revolving credit facilities totaling $1 billion ($300 million for Alliant Energy at the parent company level, $300 million for IPL and $400 million for WPL), which expire in December 2017. Information regarding commercial paper classified as short-term debt and back-stopped by the credit facilities was as follows (dollars in millions):
| Alliant Energy |  | IPL |  | WPL
| 2013 |  | 2012 |  | 2013 |  | 2012 |  | 2013 |  | 2012
December 31 |  |  |  |  |  |  |  |  |  |  |
Commercial paper: |  |  |  |  |  |  |  |  |  |  |
Amount outstanding | $279.4 |  | $217.5 |  | $— |  | $26.3 |  | $183.7 |  | $86.6
Weighted average interest rates | 0.2% |  | 0.4% |  | N/A |  | 0.4% |  | 0.1% |  | 0.3%
Weighted average remaining maturity | 4 days |  | 11 days |  | N/A |  | 2 days |  | 6 days |  | 19 days
Available credit facility capacity (a) | $720.6 |  | $732.5 |  | $300.0 |  | $223.7 |  | $216.3 |  | $313.4
| Alliant Energy |  | IPL |  | WPL
| 2013 |  | 2012 |  | 2013 |  | 2012 |  | 2013 |  | 2012
For the year ended |  |  |  |  |  |  |  |  |  |  |
Maximum amount outstanding (based on daily outstanding balances) | $293.9 |  | $217.5 |  | $26.3 |  | $35.4 |  | $190.0 |  | $86.6
Average amount outstanding (based on daily outstanding balances) | $210.5 |  | $99.8 |  | $1.3 |  | $5.9 |  | $123.5 |  | $11.7
Weighted average interest rates | 0.2% |  | 0.4% |  | 0.4% |  | 0.4% |  | 0.2% |  | 0.3%
(a) | At December 31, 2012, Alliant Energy’s and IPL’s available credit facility capacities reflect outstanding commercial paper classified as both short- and long-term debt. Refer to Note 9(b) for further discussion of $50.0 million of commercial paper outstanding at December 31, 2012 classified as long-term debt on Alliant Energy’s and IPL’s Consolidated Balance Sheets. Alliant Energy and its subsidiaries did not have any commercial paper classified as long-term debt as of December 31, 2013.
Alliant Energy’s, IPL’s and WPL’s credit facility agreements each contain a financial covenant, which requires the entities to maintain certain debt-to-capital ratios in order to borrow under the credit facilities. The required debt-to-capital ratios compared to the actual debt-to-capital ratios at December 31, 2013 were as follows:
| Alliant Energy |  | IPL |  | WPL
Requirement | Less than 65% |  | Less than 58% |  | Less than 58%
Actual | 51% |  | 45% |  | 50%
The debt component of the capital ratios includes long- and short-term debt (excluding non-recourse debt and hybrid securities to the extent the total carrying value of such hybrid securities does not exceed 15% of consolidated capital of the applicable borrower), capital lease obligations, certain letters of credit, guarantees of the foregoing and new synthetic leases. Unfunded vested benefits under qualified pension plans are not included in the debt-to-capital ratios. The equity component of the capital ratios excludes accumulated other comprehensive income (loss). (b) Long-Term Debt - Long-term debt, net as of December 31 was as follows (dollars in millions):
| 2013 |  | 2012
| Alliant Energy |  | IPL |  | WPL |  | Alliant Energy |  | IPL |  | WPL
Senior Debentures: |  |  |  |  |  |  |  |  |  |  |
3.3%, due 2015 |  | $150.0 |  |  |  | $150.0 |  |  |  | $— |  |  |  | $150.0 |  |  |  | $150.0 |  |  |  | $— |
5.875%, due 2018 | 100.0 |  |  | 100.0 |  |  | — |  |  | 100.0 |  |  | 100.0 |  |  | — |
7.25%, due 2018 | 250.0 |  |  | 250.0 |  |  | — |  |  | 250.0 |  |  | 250.0 |  |  | — |
3.65%, due 2020 | 200.0 |  |  | 200.0 |  |  | — |  |  | 200.0 |  |  | 200.0 |  |  | — |
5.5%, due 2025 | 50.0 |  |  | 50.0 |  |  | — |  |  | 50.0 |  |  | 50.0 |  |  | — |
6.45%, due 2033 | 100.0 |  |  | 100.0 |  |  | — |  |  | 100.0 |  |  | 100.0 |  |  | — |
6.3%, due 2034 | 125.0 |  |  | 125.0 |  |  | — |  |  | 125.0 |  |  | 125.0 |  |  | — |
6.25%, due 2039 | 300.0 |  |  | 300.0 |  |  | — |  |  | 300.0 |  |  | 300.0 |  |  | — |
4.7%, due 2043 (a) | 250.0 |  |  | 250.0 |  |  | — |  |  | — |  |  | — |  |  | — |
| 1,525.0 |  |  | 1,525.0 |  |  | — |  |  | 1,275.0 |  |  | 1,275.0 |  |  | — |
Debentures: |  |  |  |  |  |  |  |  |  |  |
5%, due 2019 | 250.0 |  |  | — |  |  | 250.0 |  |  | 250.0 |  |  | — |  |  | 250.0 |
4.6%, due 2020 | 150.0 |  |  | — |  |  | 150.0 |  |  | 150.0 |  |  | — |  |  | 150.0 |
2.25%, due 2022 | 250.0 |  |  | — |  |  | 250.0 |  |  | 250.0 |  |  | — |  |  | 250.0 |
6.25%, due 2034 | 100.0 |  |  | — |  |  | 100.0 |  |  | 100.0 |  |  | — |  |  | 100.0 |
6.375%, due 2037 | 300.0 |  |  | — |  |  | 300.0 |  |  | 300.0 |  |  | — |  |  | 300.0 |
7.6%, due 2038 | 250.0 |  |  | — |  |  | 250.0 |  |  | 250.0 |  |  | — |  |  | 250.0 |
| 1,300.0 |  |  | — |  |  | 1,300.0 |  |  | 1,300.0 |  |  | — |  |  | 1,300.0 |
Pollution Control Revenue Bonds: |  |  |  |  |  |  |  |  |  |  |
5%, due 2014 | 38.4 |  |  | 38.4 |  |  | — |  |  | 38.4 |  |  | 38.4 |  |  | — |
5%, due 2014 and 2015 | 24.5 |  |  | — |  |  | 24.5 |  |  | 24.5 |  |  | — |  |  | 24.5 |
5.375%, due 2015 | 14.6 |  |  | — |  |  | 14.6 |  |  | 14.6 |  |  | — |  |  | 14.6 |
| 77.5 |  |  | 38.4 |  |  | 39.1 |  |  | 77.5 |  |  | 38.4 |  |  | 39.1 |
Other: |  |  |  |  |  |  |  |  |  |  |
Commercial paper, 0.4% at December 31, 2012 (b) | — |  |  | — |  |  | — |  |  | 50.0 |  |  | 50.0 |  |  | — |
4% senior notes, due 2014 | 250.0 |  |  | — |  |  | — |  |  | 250.0 |  |  | — |  |  | — |
Term loan credit agreement through 2014, 1% at December 31, 2013 | 60.0 |  |  | — |  |  | — |  |  | 60.0 |  |  | — |  |  | — |
3.45% senior notes, due 2022 | 75.0 |  |  | — |  |  | — |  |  | 75.0 |  |  | — |  |  | — |
5.06% senior secured notes, due 2014 to 2024 | 60.5 |  |  | — |  |  | — |  |  | 61.9 |  |  | — |  |  | — |
Other, 1% at December 31, 2013, due 2014 to 2025 | 0.4 |  |  | — |  |  | — |  |  | 0.5 |  |  | — |  |  | — |
| 445.9 |  |  | — |  |  | — |  |  | 497.4 |  |  | 50.0 |  |  | — |
Subtotal | 3,348.4 |  |  | 1,563.4 |  |  | 1,339.1 |  |  | 3,149.9 |  |  | 1,363.4 |  |  | 1,339.1 |
Current maturities | (358.5 | ) |  | (38.4 | ) |  | (8.5 | ) |  | (1.5 | ) |  | — |  |  | — |
Unamortized debt (discount) and premium, net | (12.1 | ) |  | (5.0 | ) |  | (7.0 | ) |  | (11.8 | ) |  | (3.9 | ) |  | (7.6 | )
Long-term debt, net |  | $2,977.8 |  |  |  | $1,520.0 |  |  |  | $1,323.6 |  |  |  | $3,136.6 |  |  |  | $1,359.5 |  |  |  | $1,331.5 |
(a) | In 2013, IPL issued $250.0 million of 4.7% senior debentures due 2043. The proceeds from the issuance were used by IPL to reduce cash proceeds received from its sales of accounts receivable program, reduce commercial paper classified as long-term debt by $65 million and for general working capital purposes.
(b) | At December 31, 2012, $50.0 million of commercial paper was recorded in “Long-term debt, net” on Alliant Energy’s and IPL’s Consolidated Balance Sheets due to the existence of long-term credit facilities that back-stop this commercial paper balance, along with Alliant Energy’s and IPL’s intent and ability to refinance these balances on a long-term basis.
Five-Year Schedule of Debt Maturities - At December 31, 2013, debt maturities for 2014 to 2018 were as follows (in millions):
| 2014 |  | 2015 |  | 2016 |  | 2017 |  | 2018
IPL |  | $38 |  |  |  | $150 |  |  |  | $— |  |  |  | $— |  |  |  | $350 |
WPL | 9 |  |  | 31 |  |  | — |  |  | — |  |  | — |
Resources | 62 |  |  | 2 |  |  | 3 |  |  | 4 |  |  | 5 |
Alliant Energy parent company | 250 |  |  | — |  |  | — |  |  | — |  |  | — |
Alliant Energy |  | $359 |  |  |  | $183 |  |  |  | $3 |  |  |  | $4 |  |  |  | $355 |
At December 31, 2013, there were no significant sinking fund requirements related to the long-term debt on the Consolidated Balance Sheets. Indentures - Alliant Energy maintains an indenture related to its 4% senior notes due 2014. IPL maintains an indenture related to its senior debentures due 2015 through 2043. WPL maintains an indenture related to its debentures due 2019 through 2038. Sheboygan Power, Resources’ wholly-owned subsidiary, maintains an indenture related to the issuance of its 5.06% senior secured notes due 2014 to 2024. Optional Redemption Provisions - Alliant Energy and its subsidiaries have certain issuances of long-term debt that contain optional redemption provisions which, if elected by the issuer at its sole discretion, could require material redemption premium payments by the issuer. The redemption premium payments under these optional redemption provisions are variable and dependent on applicable U.S. Treasury rates at the time of redemption. At December 31, 2013, the debt issuances that contained these optional redemption provisions included all of IPL’s outstanding senior debentures, all of WPL’s outstanding debentures, Alliant Energy’s senior notes due 2014, Corporate Services’ senior notes due 2022 and Sheboygan Power’s senior secured notes due 2014 to 2024. Security Provisions - Sheboygan Power’s 5.06% senior secured notes due 2014 to 2024 are secured by Sheboygan Falls and related assets. Unamortized Debt Issuance Costs - Unamortized debt issuance costs recorded in “Deferred charges and other” on the Consolidated Balance Sheets at December 31 were as follows (in millions):
| Alliant Energy |  | IPL |  | WPL
| 2013 |  | 2012 |  | 2013 |  | 2012 |  | 2013 |  | 2012
Unamortized debt issuance costs | $19.9 |  | $19.5 |  | $9.7 |  | $8.0 |  | $9.0 |  | $9.8
Carrying Amount and Fair Value of Long-term Debt - Refer to Note 14 for information on the carrying amount and fair value of long-term debt outstanding at December 31, 2013 and 2012.

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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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