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v3.3.1.900

Debt | 12 Months Ended
--- | ---
Dec. 31, 2015
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, 2015, 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 2018. 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
| 2015 |  | 2014 |  | 2015 |  | 2014 |  | 2015 |  | 2014
December 31 |  |  |  |  |  |  |  |  |  |  |
Commercial paper: |  |  |  |  |  |  |  |  |  |  |
Amount outstanding | $159.8 |  | $141.3 |  | $— |  | $— |  | $19.9 |  | $—
Weighted average interest rates | 0.7% |  | 0.4% |  | N/A |  | N/A |  | 0.4% |  | N/A
Weighted average remaining maturity | 4 days |  | 4 days |  | N/A |  | N/A |  | 4 days |  | N/A
Available credit facility capacity | $840.2 |  | $858.7 |  | $300.0 |  | $300.0 |  | $380.1 |  | $400.0
| Alliant Energy |  | IPL |  | WPL
| 2015 |  | 2014 |  | 2015 |  | 2014 |  | 2015 |  | 2014
For the year ended |  |  |  |  |  |  |  |  |  |  |
Maximum amount outstanding (based on daily outstanding balances) | $181.2 |  | $353.8 |  | $18.4 |  | $38.0 |  | $24.7 |  | $204.7
Average amount outstanding (based on daily outstanding balances) | $119.2 |  | $255.9 |  | $0.2 |  | $0.2 |  | $2.2 |  | $122.9
Weighted average interest rates | 0.4% |  | 0.2% |  | 0.4% |  | 0.2% |  | 0.3% |  | 0.1%
The credit facility agreements and Alliant Energy’s term loan credit agreement each contain a financial covenant, which requires Alliant Energy, IPL and WPL to maintain certain debt-to-capital ratios in order to borrow under the credit facilities and term loan credit agreement. The required debt-to-capital ratios compared to the actual debt-to-capital ratios at December 31, 2015 were as follows:
| Alliant Energy |  | IPL |  | WPL
Requirement, not to exceed | 65% |  | 58% |  | 58%
Actual | 50% |  | 46% |  | 48%
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 and sales of accounts receivable 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):
| 2015 |  | 2014
| Alliant Energy |  | IPL |  | WPL |  | Alliant Energy |  | IPL |  | WPL
Senior Debentures: |  |  |  |  |  |  |  |  |  |  |
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 |  |  | — |
3.25%, due 2024 | 250.0 |  |  | 250.0 |  |  | — |  |  | 250.0 |  |  | 250.0 |  |  | — |
3.4%, due 2025 (a) | 250.0 |  |  | 250.0 |  |  | — |  |  | — |  |  | — |  |  | — |
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 | 250.0 |  |  | 250.0 |  |  | — |  |  | 250.0 |  |  | 250.0 |  |  | — |
3.3% (Retired in 2015) | — |  |  | — |  |  | — |  |  | 150.0 |  |  | 150.0 |  |  | — |
| 1,875.0 |  |  | 1,875.0 |  |  | — |  |  | 1,775.0 |  |  | 1,775.0 |  |  | — |
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 |
4.1%, due 2044 | 250.0 |  |  | — |  |  | 250.0 |  |  | 250.0 |  |  | — |  |  | 250.0 |
| 1,550.0 |  |  | — |  |  | 1,550.0 |  |  | 1,550.0 |  |  | — |  |  | 1,550.0 |
Pollution Control Revenue Bonds: |  |  |  |  |  |  |  |  |  |  |
5% (Retired in 2015) | — |  |  | — |  |  | — |  |  | 16.0 |  |  | — |  |  | 16.0 |
5.375% (Retired in 2015) | — |  |  | — |  |  | — |  |  | 14.6 |  |  | — |  |  | 14.6 |
| — |  |  | — |  |  | — |  |  | 30.6 |  |  | — |  |  | 30.6 |
Other: |  |  |  |  |  |  |  |  |  |  |
Term loan credit agreement through 2016, 1% at December 31, 2015 | 250.0 |  |  | — |  |  | — |  |  | 250.0 |  |  | — |  |  | — |
Term loan credit agreement through 2016, 1% at December 31, 2015 | 60.0 |  |  | — |  |  | — |  |  | 60.0 |  |  | — |  |  | — |
3.45% senior notes, due 2022 | 75.0 |  |  | — |  |  | — |  |  | 75.0 |  |  | — |  |  | — |
5.06% senior secured notes, due 2016 to 2024 | 56.8 |  |  | — |  |  | — |  |  | 58.9 |  |  | — |  |  | — |
Other, 1% at December 31, 2015, due 2016 to 2025 | 3.7 |  |  | — |  |  | — |  |  | 3.3 |  |  | — |  |  | — |
| 445.5 |  |  | — |  |  | — |  |  | 447.2 |  |  | — |  |  | — |
Subtotal | 3,870.5 |  |  | 1,875.0 |  |  | 1,550.0 |  |  | 3,802.8 |  |  | 1,775.0 |  |  | 1,580.6 |
Current maturities | (313.4 | ) |  | — |  |  | — |  |  | (183.0 | ) |  | (150.0 | ) |  | (30.6 | )
Unamortized debt issuance costs | (22.3 | ) |  | (11.8 | ) |  | (9.9 | ) |  | (22.4 | ) |  | (10.7 | ) |  | (10.8 | )
Unamortized debt (discount) and premium, net | (12.6 | ) |  | (6.3 | ) |  | (6.2 | ) |  | (13.1 | ) |  | (6.3 | ) |  | (6.7 | )
Long-term debt, net |  | $3,522.2 |  |  |  | $1,856.9 |  |  |  | $1,533.9 |  |  |  | $3,584.3 |  |  |  | $1,608.0 |  |  |  | $1,532.5 |
(a) | In 2015, IPL issued $250.0 million of 3.4% senior debentures due 2025. The proceeds from the issuance were used by IPL to reduce commercial paper classified as long-term debt by $111 million, reduce cash amounts received from its sales of accounts receivable program and for general corporate purposes.
Five-Year Schedule of Debt Maturities - At December 31, 2015, debt maturities for 2016 through 2020 were as follows (in millions):
| 2016 |  | 2017 |  | 2018 |  | 2019 |  | 2020
IPL |  | $— |  |  |  | $— |  |  |  | $350 |  |  |  | $— |  |  |  | $200 |
WPL | — |  |  | — |  |  | — |  |  | 250 |  |  | 150 |
Resources | 63 |  |  | 5 |  |  | 6 |  |  | 6 |  |  | 7 |
Alliant Energy parent company | 250 |  |  | — |  |  | — |  |  | — |  |  | — |
Alliant Energy |  | $313 |  |  |  | $5 |  |  |  | $356 |  |  |  | $256 |  |  |  | $357 |
At December 31, 2015, there were no significant sinking fund requirements related to the long-term debt on the balance sheets. Indentures - IPL maintains an indenture related to all of its outstanding senior debentures. WPL maintains an indenture related to all of its outstanding debentures. Sheboygan Power, LLC, Resources’ wholly-owned subsidiary, maintains an indenture related to the issuance of its 5.06% senior secured notes due 2016 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, 2015, the debt issuances that contained these optional redemption provisions included all of IPL’s outstanding senior debentures, all of WPL’s outstanding debentures, Corporate Services’ senior notes due 2022 and Sheboygan Power, LLC’s senior secured notes due 2016 to 2024. Security Provisions - Sheboygan Power, LLC’s 5.06% senior secured notes due 2016 to 2024 are secured by Sheboygan Falls and related assets. Financial Covenant - Alliant Energy’s term loan credit agreement contains a financial covenant, which requires it to maintain a certain debt-to-capital ratio in order to borrow under the agreement. Refer to Note 9(a) for further discussion. 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.
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, 2015, 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 2018. 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
| 2015 |  | 2014 |  | 2015 |  | 2014 |  | 2015 |  | 2014
December 31 |  |  |  |  |  |  |  |  |  |  |
Commercial paper: |  |  |  |  |  |  |  |  |  |  |
Amount outstanding | $159.8 |  | $141.3 |  | $— |  | $— |  | $19.9 |  | $—
Weighted average interest rates | 0.7% |  | 0.4% |  | N/A |  | N/A |  | 0.4% |  | N/A
Weighted average remaining maturity | 4 days |  | 4 days |  | N/A |  | N/A |  | 4 days |  | N/A
Available credit facility capacity | $840.2 |  | $858.7 |  | $300.0 |  | $300.0 |  | $380.1 |  | $400.0
| Alliant Energy |  | IPL |  | WPL
| 2015 |  | 2014 |  | 2015 |  | 2014 |  | 2015 |  | 2014
For the year ended |  |  |  |  |  |  |  |  |  |  |
Maximum amount outstanding (based on daily outstanding balances) | $181.2 |  | $353.8 |  | $18.4 |  | $38.0 |  | $24.7 |  | $204.7
Average amount outstanding (based on daily outstanding balances) | $119.2 |  | $255.9 |  | $0.2 |  | $0.2 |  | $2.2 |  | $122.9
Weighted average interest rates | 0.4% |  | 0.2% |  | 0.4% |  | 0.2% |  | 0.3% |  | 0.1%
The credit facility agreements and Alliant Energy’s term loan credit agreement each contain a financial covenant, which requires Alliant Energy, IPL and WPL to maintain certain debt-to-capital ratios in order to borrow under the credit facilities and term loan credit agreement. The required debt-to-capital ratios compared to the actual debt-to-capital ratios at December 31, 2015 were as follows:
| Alliant Energy |  | IPL |  | WPL
Requirement, not to exceed | 65% |  | 58% |  | 58%
Actual | 50% |  | 46% |  | 48%
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 and sales of accounts receivable 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):
| 2015 |  | 2014
| Alliant Energy |  | IPL |  | WPL |  | Alliant Energy |  | IPL |  | WPL
Senior Debentures: |  |  |  |  |  |  |  |  |  |  |
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 |  |  | — |
3.25%, due 2024 | 250.0 |  |  | 250.0 |  |  | — |  |  | 250.0 |  |  | 250.0 |  |  | — |
3.4%, due 2025 (a) | 250.0 |  |  | 250.0 |  |  | — |  |  | — |  |  | — |  |  | — |
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 | 250.0 |  |  | 250.0 |  |  | — |  |  | 250.0 |  |  | 250.0 |  |  | — |
3.3% (Retired in 2015) | — |  |  | — |  |  | — |  |  | 150.0 |  |  | 150.0 |  |  | — |
| 1,875.0 |  |  | 1,875.0 |  |  | — |  |  | 1,775.0 |  |  | 1,775.0 |  |  | — |
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 |
4.1%, due 2044 | 250.0 |  |  | — |  |  | 250.0 |  |  | 250.0 |  |  | — |  |  | 250.0 |
| 1,550.0 |  |  | — |  |  | 1,550.0 |  |  | 1,550.0 |  |  | — |  |  | 1,550.0 |
Pollution Control Revenue Bonds: |  |  |  |  |  |  |  |  |  |  |
5% (Retired in 2015) | — |  |  | — |  |  | — |  |  | 16.0 |  |  | — |  |  | 16.0 |
5.375% (Retired in 2015) | — |  |  | — |  |  | — |  |  | 14.6 |  |  | — |  |  | 14.6 |
| — |  |  | — |  |  | — |  |  | 30.6 |  |  | — |  |  | 30.6 |
Other: |  |  |  |  |  |  |  |  |  |  |
Term loan credit agreement through 2016, 1% at December 31, 2015 | 250.0 |  |  | — |  |  | — |  |  | 250.0 |  |  | — |  |  | — |
Term loan credit agreement through 2016, 1% at December 31, 2015 | 60.0 |  |  | — |  |  | — |  |  | 60.0 |  |  | — |  |  | — |
3.45% senior notes, due 2022 | 75.0 |  |  | — |  |  | — |  |  | 75.0 |  |  | — |  |  | — |
5.06% senior secured notes, due 2016 to 2024 | 56.8 |  |  | — |  |  | — |  |  | 58.9 |  |  | — |  |  | — |
Other, 1% at December 31, 2015, due 2016 to 2025 | 3.7 |  |  | — |  |  | — |  |  | 3.3 |  |  | — |  |  | — |
| 445.5 |  |  | — |  |  | — |  |  | 447.2 |  |  | — |  |  | — |
Subtotal | 3,870.5 |  |  | 1,875.0 |  |  | 1,550.0 |  |  | 3,802.8 |  |  | 1,775.0 |  |  | 1,580.6 |
Current maturities | (313.4 | ) |  | — |  |  | — |  |  | (183.0 | ) |  | (150.0 | ) |  | (30.6 | )
Unamortized debt issuance costs | (22.3 | ) |  | (11.8 | ) |  | (9.9 | ) |  | (22.4 | ) |  | (10.7 | ) |  | (10.8 | )
Unamortized debt (discount) and premium, net | (12.6 | ) |  | (6.3 | ) |  | (6.2 | ) |  | (13.1 | ) |  | (6.3 | ) |  | (6.7 | )
Long-term debt, net |  | $3,522.2 |  |  |  | $1,856.9 |  |  |  | $1,533.9 |  |  |  | $3,584.3 |  |  |  | $1,608.0 |  |  |  | $1,532.5 |
(a) | In 2015, IPL issued $250.0 million of 3.4% senior debentures due 2025. The proceeds from the issuance were used by IPL to reduce commercial paper classified as long-term debt by $111 million, reduce cash amounts received from its sales of accounts receivable program and for general corporate purposes.
Five-Year Schedule of Debt Maturities - At December 31, 2015, debt maturities for 2016 through 2020 were as follows (in millions):
| 2016 |  | 2017 |  | 2018 |  | 2019 |  | 2020
IPL |  | $— |  |  |  | $— |  |  |  | $350 |  |  |  | $— |  |  |  | $200 |
WPL | — |  |  | — |  |  | — |  |  | 250 |  |  | 150 |
Resources | 63 |  |  | 5 |  |  | 6 |  |  | 6 |  |  | 7 |
Alliant Energy parent company | 250 |  |  | — |  |  | — |  |  | — |  |  | — |
Alliant Energy |  | $313 |  |  |  | $5 |  |  |  | $356 |  |  |  | $256 |  |  |  | $357 |
At December 31, 2015, there were no significant sinking fund requirements related to the long-term debt on the balance sheets. Indentures - IPL maintains an indenture related to all of its outstanding senior debentures. WPL maintains an indenture related to all of its outstanding debentures. Sheboygan Power, LLC, Resources’ wholly-owned subsidiary, maintains an indenture related to the issuance of its 5.06% senior secured notes due 2016 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, 2015, the debt issuances that contained these optional redemption provisions included all of IPL’s outstanding senior debentures, all of WPL’s outstanding debentures, Corporate Services’ senior notes due 2022 and Sheboygan Power, LLC’s senior secured notes due 2016 to 2024. Security Provisions - Sheboygan Power, LLC’s 5.06% senior secured notes due 2016 to 2024 are secured by Sheboygan Falls and related assets. Financial Covenant - Alliant Energy’s term loan credit agreement contains a financial covenant, which requires it to maintain a certain debt-to-capital ratio in order to borrow under the agreement. Refer to Note 9(a) for further discussion. 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.
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, 2015, 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 2018. 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
| 2015 |  | 2014 |  | 2015 |  | 2014 |  | 2015 |  | 2014
December 31 |  |  |  |  |  |  |  |  |  |  |
Commercial paper: |  |  |  |  |  |  |  |  |  |  |
Amount outstanding | $159.8 |  | $141.3 |  | $— |  | $— |  | $19.9 |  | $—
Weighted average interest rates | 0.7% |  | 0.4% |  | N/A |  | N/A |  | 0.4% |  | N/A
Weighted average remaining maturity | 4 days |  | 4 days |  | N/A |  | N/A |  | 4 days |  | N/A
Available credit facility capacity | $840.2 |  | $858.7 |  | $300.0 |  | $300.0 |  | $380.1 |  | $400.0
| Alliant Energy |  | IPL |  | WPL
| 2015 |  | 2014 |  | 2015 |  | 2014 |  | 2015 |  | 2014
For the year ended |  |  |  |  |  |  |  |  |  |  |
Maximum amount outstanding (based on daily outstanding balances) | $181.2 |  | $353.8 |  | $18.4 |  | $38.0 |  | $24.7 |  | $204.7
Average amount outstanding (based on daily outstanding balances) | $119.2 |  | $255.9 |  | $0.2 |  | $0.2 |  | $2.2 |  | $122.9
Weighted average interest rates | 0.4% |  | 0.2% |  | 0.4% |  | 0.2% |  | 0.3% |  | 0.1%
The credit facility agreements and Alliant Energy’s term loan credit agreement each contain a financial covenant, which requires Alliant Energy, IPL and WPL to maintain certain debt-to-capital ratios in order to borrow under the credit facilities and term loan credit agreement. The required debt-to-capital ratios compared to the actual debt-to-capital ratios at December 31, 2015 were as follows:
| Alliant Energy |  | IPL |  | WPL
Requirement, not to exceed | 65% |  | 58% |  | 58%
Actual | 50% |  | 46% |  | 48%
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 and sales of accounts receivable 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):
| 2015 |  | 2014
| Alliant Energy |  | IPL |  | WPL |  | Alliant Energy |  | IPL |  | WPL
Senior Debentures: |  |  |  |  |  |  |  |  |  |  |
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 |  |  | — |
3.25%, due 2024 | 250.0 |  |  | 250.0 |  |  | — |  |  | 250.0 |  |  | 250.0 |  |  | — |
3.4%, due 2025 (a) | 250.0 |  |  | 250.0 |  |  | — |  |  | — |  |  | — |  |  | — |
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 | 250.0 |  |  | 250.0 |  |  | — |  |  | 250.0 |  |  | 250.0 |  |  | — |
3.3% (Retired in 2015) | — |  |  | — |  |  | — |  |  | 150.0 |  |  | 150.0 |  |  | — |
| 1,875.0 |  |  | 1,875.0 |  |  | — |  |  | 1,775.0 |  |  | 1,775.0 |  |  | — |
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 |
4.1%, due 2044 | 250.0 |  |  | — |  |  | 250.0 |  |  | 250.0 |  |  | — |  |  | 250.0 |
| 1,550.0 |  |  | — |  |  | 1,550.0 |  |  | 1,550.0 |  |  | — |  |  | 1,550.0 |
Pollution Control Revenue Bonds: |  |  |  |  |  |  |  |  |  |  |
5% (Retired in 2015) | — |  |  | — |  |  | — |  |  | 16.0 |  |  | — |  |  | 16.0 |
5.375% (Retired in 2015) | — |  |  | — |  |  | — |  |  | 14.6 |  |  | — |  |  | 14.6 |
| — |  |  | — |  |  | — |  |  | 30.6 |  |  | — |  |  | 30.6 |
Other: |  |  |  |  |  |  |  |  |  |  |
Term loan credit agreement through 2016, 1% at December 31, 2015 | 250.0 |  |  | — |  |  | — |  |  | 250.0 |  |  | — |  |  | — |
Term loan credit agreement through 2016, 1% at December 31, 2015 | 60.0 |  |  | — |  |  | — |  |  | 60.0 |  |  | — |  |  | — |
3.45% senior notes, due 2022 | 75.0 |  |  | — |  |  | — |  |  | 75.0 |  |  | — |  |  | — |
5.06% senior secured notes, due 2016 to 2024 | 56.8 |  |  | — |  |  | — |  |  | 58.9 |  |  | — |  |  | — |
Other, 1% at December 31, 2015, due 2016 to 2025 | 3.7 |  |  | — |  |  | — |  |  | 3.3 |  |  | — |  |  | — |
| 445.5 |  |  | — |  |  | — |  |  | 447.2 |  |  | — |  |  | — |
Subtotal | 3,870.5 |  |  | 1,875.0 |  |  | 1,550.0 |  |  | 3,802.8 |  |  | 1,775.0 |  |  | 1,580.6 |
Current maturities | (313.4 | ) |  | — |  |  | — |  |  | (183.0 | ) |  | (150.0 | ) |  | (30.6 | )
Unamortized debt issuance costs | (22.3 | ) |  | (11.8 | ) |  | (9.9 | ) |  | (22.4 | ) |  | (10.7 | ) |  | (10.8 | )
Unamortized debt (discount) and premium, net | (12.6 | ) |  | (6.3 | ) |  | (6.2 | ) |  | (13.1 | ) |  | (6.3 | ) |  | (6.7 | )
Long-term debt, net |  | $3,522.2 |  |  |  | $1,856.9 |  |  |  | $1,533.9 |  |  |  | $3,584.3 |  |  |  | $1,608.0 |  |  |  | $1,532.5 |
(a) | In 2015, IPL issued $250.0 million of 3.4% senior debentures due 2025. The proceeds from the issuance were used by IPL to reduce commercial paper classified as long-term debt by $111 million, reduce cash amounts received from its sales of accounts receivable program and for general corporate purposes.
Five-Year Schedule of Debt Maturities - At December 31, 2015, debt maturities for 2016 through 2020 were as follows (in millions):
| 2016 |  | 2017 |  | 2018 |  | 2019 |  | 2020
IPL |  | $— |  |  |  | $— |  |  |  | $350 |  |  |  | $— |  |  |  | $200 |
WPL | — |  |  | — |  |  | — |  |  | 250 |  |  | 150 |
Resources | 63 |  |  | 5 |  |  | 6 |  |  | 6 |  |  | 7 |
Alliant Energy parent company | 250 |  |  | — |  |  | — |  |  | — |  |  | — |
Alliant Energy |  | $313 |  |  |  | $5 |  |  |  | $356 |  |  |  | $256 |  |  |  | $357 |
At December 31, 2015, there were no significant sinking fund requirements related to the long-term debt on the balance sheets. Indentures - IPL maintains an indenture related to all of its outstanding senior debentures. WPL maintains an indenture related to all of its outstanding debentures. Sheboygan Power, LLC, Resources’ wholly-owned subsidiary, maintains an indenture related to the issuance of its 5.06% senior secured notes due 2016 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, 2015, the debt issuances that contained these optional redemption provisions included all of IPL’s outstanding senior debentures, all of WPL’s outstanding debentures, Corporate Services’ senior notes due 2022 and Sheboygan Power, LLC’s senior secured notes due 2016 to 2024. Security Provisions - Sheboygan Power, LLC’s 5.06% senior secured notes due 2016 to 2024 are secured by Sheboygan Falls and related assets. Financial Covenant - Alliant Energy’s term loan credit agreement contains a financial covenant, which requires it to maintain a certain debt-to-capital ratio in order to borrow under the agreement. Refer to Note 9(a) for further discussion. 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.

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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 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 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 19, 20, 22 -Article 5 + Details
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