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Fair Value Measurements | 6 Months Ended
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Jun. 30, 2013
Fair Value Measurements | FAIR VALUE MEASUREMENTS Fair Value of Financial Instruments - The carrying amounts of Alliant Energy’s, IPL’s and WPL’s current assets and current liabilities approximate fair value because of the short maturity of such financial instruments. Carrying amounts and the related estimated fair values of other financial instruments were as follows (in millions):
| Alliant Energy |  | IPL |  | WPL
| Carrying Amount |  | Fair Value |  | Carrying Amount |  | Fair Value |  | Carrying Amount |  | Fair Value
June 30, 2013 |  |  |  |  |  |  |  |  |  |  |
Assets: |  |  |  |  |  |  |  |  |  |  |
Derivative assets (Note 11) |  | $60.5 |  |  |  | $60.5 |  |  |  | $45.1 |  |  |  | $45.1 |  |  |  | $15.4 |  |  |  | $15.4 |
Deferred proceeds (sales of receivables) (Note 3(a)) | 69.3 |  |  | 69.3 |  |  | 69.3 |  |  | 69.3 |  |  | — |  |  | — |
Capitalization and liabilities: |  |  |  |  |  |  |  |  |  |  |
Long-term debt (including current maturities) (Note 8(b)) | 3,142.9 |  |  | 3,619.5 |  |  | 1,364.7 |  |  | 1,586.8 |  |  | 1,331.9 |  |  | 1,572.1 |
Cumulative preferred stock (Note 7) | 200.0 |  |  | 188.4 |  |  | 200.0 |  |  | 188.4 |  |  | — |  |  | — |
Derivative liabilities (Note 11) | 37.1 |  |  | 37.1 |  |  | 9.7 |  |  | 9.7 |  |  | 27.4 |  |  | 27.4 |
| Alliant Energy |  | IPL |  | WPL
| Carrying Amount |  | Fair Value |  | Carrying Amount |  | Fair Value |  | Carrying Amount |  | Fair Value
December 31, 2012 |  |  |  |  |  |  |  |  |  |  |
Assets: |  |  |  |  |  |  |  |  |  |  |
Derivative assets (Note 11) |  | $26.2 |  |  |  | $26.2 |  |  |  | $17.5 |  |  |  | $17.5 |  |  |  | $8.7 |  |  |  | $8.7 |
Deferred proceeds (sales of receivables) (Note 3(a)) | 66.8 |  |  | 66.8 |  |  | 66.8 |  |  | 66.8 |  |  | — |  |  | — |
Capitalization and liabilities: |  |  |  |  |  |  |  |  |  |  |
Long-term debt (including current maturities) (Note 8(b)) | 3,138.1 |  |  | 3,860.5 |  |  | 1,359.5 |  |  | 1,679.9 |  |  | 1,331.5 |  |  | 1,713.3 |
Cumulative preferred stock (Note 7) | 205.1 |  |  | 212.6 |  |  | 145.1 |  |  | 151.8 |  |  | 60.0 |  |  | 60.8 |
Derivative liabilities (Note 11) | 40.4 |  |  | 40.4 |  |  | 16.1 |  |  | 16.1 |  |  | 24.3 |  |  | 24.3 |
Valuation Hierarchy - Fair value measurement accounting establishes a fair value hierarchy that prioritizes the inputs to valuation techniques used to measure fair value. The three levels of the fair value hierarchy and examples of each are as follows: Level 1 - Pricing inputs are quoted prices available in active markets for identical assets or liabilities as of the reporting date. As of June 30, 2013, Level 1 items included IPL’s 5.1% cumulative preferred stock. As of December 31, 2012, Level 1 items included IPL’s 8.375% cumulative preferred stock and WPL’s 4.50% cumulative preferred stock. Level 2 - Pricing inputs are quoted prices for similar assets or liabilities in active markets or quoted prices for identical or similar assets or liabilities in markets that are not active as of the reporting date. As of June 30, 2013 and December 31, 2012, Level 2 items included certain of IPL’s and WPL’s non-exchange traded commodity contracts and substantially all of the long-term debt instruments. Level 2 items as of December 31, 2012 also included the remainder of WPL’s cumulative preferred stock. Level 3 - Pricing inputs are unobservable inputs for assets or liabilities for which little or no market data exist and require significant management judgment or estimation. As of June 30, 2013 and December 31, 2012, Level 3 items included IPL’s deferred proceeds, and IPL’s and WPL’s financial transmission rights (FTRs) and certain non-exchange traded commodity contracts. The fair value hierarchy gives the highest priority to quoted prices in active markets (Level 1) and the lowest priority to unobservable data (Level 3). In some cases, the inputs used to measure fair value might fall in different levels of the fair value hierarchy. The lowest level input that is significant to a fair value measurement in its entirety determines the applicable level in the fair value hierarchy. Assessing the significance of a particular input to the fair value measurement in its entirety requires judgment, considering factors specific to the asset or liability. Valuation Techniques - Derivative assets and derivative liabilities - Alliant Energy, IPL and WPL periodically use derivative instruments for risk management purposes to mitigate exposures to fluctuations in certain commodity prices and transmission congestion costs, and maintain risk policies that govern the use of such derivative instruments. As of June 30, 2013 and December 31, 2012, Alliant Energy’s, IPL’s and WPL’s derivative instruments were not designated as hedging instruments and included the following:
Risk management purpose | Type of instrument
Mitigate pricing volatility for: |
Electricity purchased to supply customers | Electric swap, swaption and physical purchase contracts (IPL and WPL)
Fuel used to supply natural gas-fired electric generating facilities | Natural gas swap and physical purchase contracts (IPL and WPL)
| Natural gas options (WPL)
Natural gas supplied to retail customers | Natural gas options and physical purchase contracts (IPL and WPL)
| Natural gas swap contracts (IPL)
Fuel used at coal-fired generating facilities | Coal physical purchase contract with volumetric optionality (WPL)
Optimize the value of natural gas pipeline capacity | Natural gas physical purchase and sale contracts (IPL and WPL)
| Natural gas swap contracts (IPL)
Manage transmission congestion costs | FTRs (IPL and WPL)
IPL’s and WPL’s swap, swaption, option and physical forward commodity contracts were non-exchange-based derivative instruments and were valued using indicative price quotations from a pricing vendor that provides daily exchange forward price settlements, from broker or dealer quotations, from market publications or from on-line exchanges. The indicative price quotations reflected the average of the bid-ask mid-point prices and were obtained from sources believed to provide the most liquid market for the commodity. IPL and WPL corroborated a portion of these indicative price quotations using quoted prices for similar assets or liabilities in active markets and categorized derivative instruments based on such indicative price quotations as Level 2. IPL’s and WPL’s commodity contracts that were valued using indicative price quotations based on significant assumptions such as seasonal or monthly shaping and indicative price quotations that could not be readily corroborated were categorized as Level 3. IPL’s and WPL’s swap, swaption, option and physical forward commodity contracts were predominately at liquid trading points. IPL’s and WPL’s FTRs were valued using monthly or annual auction shadow prices from relevant auctions and were categorized as Level 3. Refer to Note 11 for additional details of derivative assets and derivative liabilities. Level 3 inputs include observable and unobservable inputs used in the fair value measurements of IPL’s and WPL’s commodity contracts. The observable inputs are obtained from third-party pricing sources, counterparties and brokers and include bids, offers, historical transactions (including historical price differences between locations with both observable and unobservable prices) and executed trades. The significant unobservable inputs used in the fair value measurement of IPL’s and WPL’s commodity contracts are forecasted electricity, natural gas and coal prices, and the expected volatility of such prices. Significant changes in any of those inputs would result in a significantly lower or higher fair value measurement. Deferred proceeds (sales of receivables) - The fair value of IPL’s deferred proceeds related to its sales of receivables program was calculated each reporting date using the cost approach valuation technique. The fair value represents the carrying amount of receivables sold less the allowance for doubtful accounts associated with the receivables sold and cash proceeds received from the receivables sold due to the short-term nature of the collection period. These inputs were considered unobservable and deferred proceeds were categorized as Level 3. Deferred proceeds represent IPL’s maximum exposure to loss related to the receivables sold. Refer to Note 3(a) for additional information regarding deferred proceeds. Long-term debt (including current maturities) - For long-term debt instruments that are actively traded, the fair value was based upon quoted market prices for similar liabilities on each reporting date. For long-term debt instruments that are not actively traded, the fair value was based on a discounted cash flow methodology and utilizes assumptions of current market pricing curves at each reporting date. Refer to Note 8(b) for additional information regarding long-term debt. Cumulative preferred stock - As of June 30, 2013, the fair value of IPL’s 5.1% cumulative preferred stock was based on its closing market price quoted by the New York Stock Exchange. As of December 31, 2012, the fair value of IPL’s 8.375% cumulative preferred stock was based on its closing market price quoted by the New York Stock Exchange, the fair value of WPL’s 4.50% cumulative preferred stock was based on the closing market price quoted by the NYSE Amex LLC, and the fair value of WPL’s remaining preferred stock was calculated based on the market yield of similar securities. Refer to Note 7 for additional information regarding cumulative preferred stock. Items subject to fair value measurement disclosure requirements were as follows (in millions):
Alliant Energy | June 30, 2013 |  | December 31, 2012
| Fair |  | Level |  | Level |  | Level |  | Fair |  | Level |  | Level |  | Level
| Value |  | 1 |  | 2 |  | 3 |  | Value |  | 1 |  | 2 |  | 3
Assets: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Derivatives - commodity contracts |  | $60.5 |  |  |  | $— |  |  |  | $13.7 |  |  |  | $46.8 |  |  |  | $26.2 |  |  |  | $— |  |  |  | $4.8 |  |  |  | $21.4 |
Deferred proceeds | 69.3 |  |  | — |  |  | — |  |  | 69.3 |  |  | 66.8 |  |  | — |  |  | — |  |  | 66.8 |
Capitalization and liabilities: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Long-term debt (including current maturities) | 3,619.5 |  |  | — |  |  | 3,619.1 |  |  | 0.4 |  |  | 3,860.5 |  |  | — |  |  | 3,860.0 |  |  | 0.5 |
Cumulative preferred stock | 188.4 |  |  | 188.4 |  |  | — |  |  | — |  |  | 212.6 |  |  | 162.3 |  |  | 50.3 |  |  | — |
Derivatives - commodity contracts | 37.1 |  |  | — |  |  | 32.8 |  |  | 4.3 |  |  | 40.4 |  |  | — |  |  | 30.9 |  |  | 9.5 |
IPL | June 30, 2013 |  | December 31, 2012
| Fair |  | Level |  | Level |  | Level |  | Fair |  | Level |  | Level |  | Level
| Value |  | 1 |  | 2 |  | 3 |  | Value |  | 1 |  | 2 |  | 3
Assets: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Derivatives - commodity contracts |  | $45.1 |  |  |  | $— |  |  |  | $3.0 |  |  |  | $42.1 |  |  |  | $17.5 |  |  |  | $— |  |  |  | $3.1 |  |  |  | $14.4 |
Deferred proceeds | 69.3 |  |  | — |  |  | — |  |  | 69.3 |  |  | 66.8 |  |  | — |  |  | — |  |  | 66.8 |
Capitalization and liabilities: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Long-term debt | 1,586.8 |  |  | — |  |  | 1,586.8 |  |  | — |  |  | 1,679.9 |  |  | — |  |  | 1,679.9 |  |  | — |
Cumulative preferred stock | 188.4 |  |  | 188.4 |  |  | — |  |  | — |  |  | 151.8 |  |  | 151.8 |  |  | — |  |  | — |
Derivatives - commodity contracts | 9.7 |  |  | — |  |  | 8.2 |  |  | 1.5 |  |  | 16.1 |  |  | — |  |  | 14.2 |  |  | 1.9 |
WPL | June 30, 2013 |  | December 31, 2012
| Fair |  | Level |  | Level |  | Level |  | Fair |  | Level |  | Level |  | Level
| Value |  | 1 |  | 2 |  | 3 |  | Value |  | 1 |  | 2 |  | 3
Assets: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Derivatives - commodity contracts |  | $15.4 |  |  |  | $— |  |  |  | $10.7 |  |  |  | $4.7 |  |  |  | $8.7 |  |  |  | $— |  |  |  | $1.7 |  |  |  | $7.0 |
Capitalization and liabilities: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Long-term debt | 1,572.1 |  |  | — |  |  | 1,572.1 |  |  | — |  |  | 1,713.3 |  |  | — |  |  | 1,713.3 |  |  | — |
Cumulative preferred stock | — |  |  | — |  |  | — |  |  | — |  |  | 60.8 |  |  | 10.5 |  |  | 50.3 |  |  | — |
Derivatives - commodity contracts | 27.4 |  |  | — |  |  | 24.6 |  |  | 2.8 |  |  | 24.3 |  |  | — |  |  | 16.7 |  |  | 7.6 |
Alliant Energy, IPL and WPL generally record gains and losses from IPL’s and WPL’s derivative instruments with offsets to regulatory assets or regulatory liabilities, based on their fuel and natural gas cost recovery mechanisms, as well as other specific regulatory authorizations. Based on these recovery mechanisms, the changes in the fair value of derivative liabilities resulted in comparable changes to regulatory assets, and the changes in the fair value of derivative assets resulted in comparable changes to regulatory liabilities on the Condensed Consolidated Balance Sheets. Information for fair value measurements using significant unobservable inputs (Level 3 inputs) was as follows (in millions):
Alliant Energy | Commodity Contract Derivative |  |
| Assets and (Liabilities), net |  | Deferred Proceeds
Three Months Ended June 30 | 2013 |  | 2012 |  | 2013 |  | 2012
Beginning balance, April 1 |  | $4.9 |  |  |  | ($15.1 | ) |  |  | $122.1 |  |  |  | $32.9 |
Total net gains (losses) (realized/unrealized) included in changes in net assets (a) | (1.2 | ) |  | 3.0 |  |  | — |  |  | — |
Transfers into Level 3 (b) | — |  |  | (0.6 | ) |  | — |  |  | — |
Transfers out of Level 3 (c) | — |  |  | 0.4 |  |  | — |  |  | — |
Purchases | 50.9 |  |  | 35.8 |  |  | — |  |  | — |
Settlements (d) | (12.1 | ) |  | (4.7 | ) |  | (52.8 | ) |  | 48.8 |
Ending balance, June 30 |  | $42.5 |  |  |  | $18.8 |  |  |  | $69.3 |  |  |  | $81.7 |
The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at June 30 (a) |  | ($1.2 | ) |  |  | $3.5 |  |  |  | $— |  |  |  | $— |
Alliant Energy | Commodity Contract Derivative |  |
| Assets and (Liabilities), net |  | Deferred Proceeds
Six Months Ended June 30 | 2013 |  | 2012 |  | 2013 |  | 2012
Beginning balance, January 1 |  | $11.9 |  |  |  | ($0.9 | ) |  |  | $66.8 |  |  |  | $53.7 |
Total net losses (realized/unrealized) included in changes in net assets (a) | (3.0 | ) |  | (6.3 | ) |  | — |  |  | — |
Transfers into Level 3 (b) | — |  |  | (2.3 | ) |  | — |  |  | — |
Transfers out of Level 3 (c) | 3.6 |  |  | 0.3 |  |  | — |  |  | — |
Purchases | 50.9 |  |  | 35.8 |  |  | — |  |  | — |
Settlements (d) | (20.9 | ) |  | (7.8 | ) |  | 2.5 |  |  | 28.0 |
Ending balance, June 30 |  | $42.5 |  |  |  | $18.8 |  |  |  | $69.3 |  |  |  | $81.7 |
The amount of total net losses for the period included in changes in net assets attributable to the change in unrealized losses relating to assets and liabilities held at June 30 (a) |  | ($3.0 | ) |  |  | ($4.1 | ) |  |  | $— |  |  |  | $— |
IPL | Commodity Contract Derivative |  |
| Assets and (Liabilities), net |  | Deferred Proceeds
Three Months Ended June 30 | 2013 |  | 2012 |  | 2013 |  | 2012
Beginning balance, April 1 |  | $4.3 |  |  |  | ($11.4 | ) |  |  | $122.1 |  |  |  | $32.9 |
Total net gains (losses) (realized/unrealized) included in changes in net assets (a) | (0.1 | ) |  | 2.9 |  |  | — |  |  | — |
Transfers into Level 3 (b) | — |  |  | (0.2 | ) |  | — |  |  | — |
Purchases | 46.1 |  |  | 26.8 |  |  | — |  |  | — |
Settlements (d) | (9.7 | ) |  | (4.0 | ) |  | (52.8 | ) |  | 48.8 |
Ending balance, June 30 |  | $40.6 |  |  |  | $14.1 |  |  |  | $69.3 |  |  |  | $81.7 |
The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at June 30 (a) |  | ($0.1 | ) |  |  | $3.6 |  |  |  | $— |  |  |  | $— |
IPL | Commodity Contract Derivative |  |
| Assets and (Liabilities), net |  | Deferred Proceeds
Six Months Ended June 30 | 2013 |  | 2012 |  | 2013 |  | 2012
Beginning balance, January 1 |  | $12.5 |  |  |  | $4.3 |  |  |  | $66.8 |  |  |  | $53.7 |
Total net losses (realized/unrealized) included in changes in net assets (a) | (3.0 | ) |  | (9.4 | ) |  | — |  |  | — |
Transfers into Level 3 (b) | — |  |  | (1.3 | ) |  | — |  |  | — |
Transfers out of Level 3 (c) | 1.1 |  |  | — |  |  | — |  |  | — |
Purchases | 46.1 |  |  | 26.8 |  |  | — |  |  | — |
Settlements (d) | (16.1 | ) |  | (6.3 | ) |  | 2.5 |  |  | 28.0 |
Ending balance, June 30 |  | $40.6 |  |  |  | $14.1 |  |  |  | $69.3 |  |  |  | $81.7 |
The amount of total net losses for the period included in changes in net assets attributable to the change in unrealized losses relating to assets and liabilities held at June 30 (a) |  | ($3.0 | ) |  |  | ($7.0 | ) |  |  | $— |  |  |  | $— |
WPL | Commodity Contract Derivative
| Assets and (Liabilities), net
Three Months Ended June 30 | 2013 |  | 2012
Beginning balance, April 1 |  | $0.6 |  |  |  | ($3.7 | )
Total net gains (losses) (realized/unrealized) included in changes in net assets (a) | (1.1 | ) |  | 0.1 |
Transfers into Level 3 (b) | — |  |  | (0.4 | )
Transfers out of Level 3 (c) | — |  |  | 0.4 |
Purchases | 4.8 |  |  | 9.0 |
Settlements | (2.4 | ) |  | (0.7 | )
Ending balance, June 30 |  | $1.9 |  |  |  | $4.7 |
The amount of total net losses for the period included in changes in net assets attributable to the change in unrealized losses relating to assets and liabilities held at June 30 (a) |  | ($1.1 | ) |  |  | ($0.1 | )
WPL | Commodity Contract Derivative
| Assets and (Liabilities), net
Six Months Ended June 30 | 2013 |  | 2012
Beginning balance, January 1 |  | ($0.6 | ) |  |  | ($5.2 | )
Total net gains (realized/unrealized) included in changes in net assets (a) | — |  |  | 3.1 |
Transfers into Level 3 (b) | — |  |  | (1.0 | )
Transfers out of Level 3 (c) | 2.5 |  |  | 0.3 |
Purchases | 4.8 |  |  | 9.0 |
Settlements | (4.8 | ) |  | (1.5 | )
Ending balance, June 30 |  | $1.9 |  |  |  | $4.7 |
The amount of total net gains for the period included in changes in net assets attributable to the change in unrealized gains relating to assets and liabilities held at June 30 (a) |  | $— |  |  |  | $2.9 |
(a) | Gains and losses related to derivative assets and derivative liabilities are recorded in “Regulatory assets” and “Regulatory liabilities” on the Condensed Consolidated Balance Sheets.
(b) | Markets for similar assets and liabilities became inactive and observable market inputs became unavailable for transfers into Level 3. The transfers were valued as of the beginning of the period.
(c) | Observable market inputs became available for certain commodity contracts previously classified as Level 3 for transfers out of Level 3. The transfers were valued as of the beginning of the period.
(d) | Settlements related to deferred proceeds are due to the change in the carrying amount of receivables sold less the allowance for doubtful accounts associated with the receivables sold and cash proceeds received from the receivables sold.
Commodity Contracts - As of June 30, 2013, the fair value of Alliant Energy’s, IPL’s and WPL’s electric, natural gas and coal commodity contracts categorized as Level 3, excluding FTRs, were recognized as net derivative liabilities of $2.7 million, $0.4 million and $2.3 million, respectively. As of June 30, 2013, Alliant Energy’s, IPL’s and WPL’s FTRs classified as Level 3 were recognized as net derivative assets of $45.2 million, $41.0 million and $4.2 million, respectively.
IPL [Member] |
Fair Value Measurements | FAIR VALUE MEASUREMENTS Fair Value of Financial Instruments - The carrying amounts of Alliant Energy’s, IPL’s and WPL’s current assets and current liabilities approximate fair value because of the short maturity of such financial instruments. Carrying amounts and the related estimated fair values of other financial instruments were as follows (in millions):
| Alliant Energy |  | IPL |  | WPL
| Carrying Amount |  | Fair Value |  | Carrying Amount |  | Fair Value |  | Carrying Amount |  | Fair Value
June 30, 2013 |  |  |  |  |  |  |  |  |  |  |
Assets: |  |  |  |  |  |  |  |  |  |  |
Derivative assets (Note 11) |  | $60.5 |  |  |  | $60.5 |  |  |  | $45.1 |  |  |  | $45.1 |  |  |  | $15.4 |  |  |  | $15.4 |
Deferred proceeds (sales of receivables) (Note 3(a)) | 69.3 |  |  | 69.3 |  |  | 69.3 |  |  | 69.3 |  |  | — |  |  | — |
Capitalization and liabilities: |  |  |  |  |  |  |  |  |  |  |
Long-term debt (including current maturities) (Note 8(b)) | 3,142.9 |  |  | 3,619.5 |  |  | 1,364.7 |  |  | 1,586.8 |  |  | 1,331.9 |  |  | 1,572.1 |
Cumulative preferred stock (Note 7) | 200.0 |  |  | 188.4 |  |  | 200.0 |  |  | 188.4 |  |  | — |  |  | — |
Derivative liabilities (Note 11) | 37.1 |  |  | 37.1 |  |  | 9.7 |  |  | 9.7 |  |  | 27.4 |  |  | 27.4 |
| Alliant Energy |  | IPL |  | WPL
| Carrying Amount |  | Fair Value |  | Carrying Amount |  | Fair Value |  | Carrying Amount |  | Fair Value
December 31, 2012 |  |  |  |  |  |  |  |  |  |  |
Assets: |  |  |  |  |  |  |  |  |  |  |
Derivative assets (Note 11) |  | $26.2 |  |  |  | $26.2 |  |  |  | $17.5 |  |  |  | $17.5 |  |  |  | $8.7 |  |  |  | $8.7 |
Deferred proceeds (sales of receivables) (Note 3(a)) | 66.8 |  |  | 66.8 |  |  | 66.8 |  |  | 66.8 |  |  | — |  |  | — |
Capitalization and liabilities: |  |  |  |  |  |  |  |  |  |  |
Long-term debt (including current maturities) (Note 8(b)) | 3,138.1 |  |  | 3,860.5 |  |  | 1,359.5 |  |  | 1,679.9 |  |  | 1,331.5 |  |  | 1,713.3 |
Cumulative preferred stock (Note 7) | 205.1 |  |  | 212.6 |  |  | 145.1 |  |  | 151.8 |  |  | 60.0 |  |  | 60.8 |
Derivative liabilities (Note 11) | 40.4 |  |  | 40.4 |  |  | 16.1 |  |  | 16.1 |  |  | 24.3 |  |  | 24.3 |
Valuation Hierarchy - Fair value measurement accounting establishes a fair value hierarchy that prioritizes the inputs to valuation techniques used to measure fair value. The three levels of the fair value hierarchy and examples of each are as follows: Level 1 - Pricing inputs are quoted prices available in active markets for identical assets or liabilities as of the reporting date. As of June 30, 2013, Level 1 items included IPL’s 5.1% cumulative preferred stock. As of December 31, 2012, Level 1 items included IPL’s 8.375% cumulative preferred stock and WPL’s 4.50% cumulative preferred stock. Level 2 - Pricing inputs are quoted prices for similar assets or liabilities in active markets or quoted prices for identical or similar assets or liabilities in markets that are not active as of the reporting date. As of June 30, 2013 and December 31, 2012, Level 2 items included certain of IPL’s and WPL’s non-exchange traded commodity contracts and substantially all of the long-term debt instruments. Level 2 items as of December 31, 2012 also included the remainder of WPL’s cumulative preferred stock. Level 3 - Pricing inputs are unobservable inputs for assets or liabilities for which little or no market data exist and require significant management judgment or estimation. As of June 30, 2013 and December 31, 2012, Level 3 items included IPL’s deferred proceeds, and IPL’s and WPL’s financial transmission rights (FTRs) and certain non-exchange traded commodity contracts. The fair value hierarchy gives the highest priority to quoted prices in active markets (Level 1) and the lowest priority to unobservable data (Level 3). In some cases, the inputs used to measure fair value might fall in different levels of the fair value hierarchy. The lowest level input that is significant to a fair value measurement in its entirety determines the applicable level in the fair value hierarchy. Assessing the significance of a particular input to the fair value measurement in its entirety requires judgment, considering factors specific to the asset or liability. Valuation Techniques - Derivative assets and derivative liabilities - Alliant Energy, IPL and WPL periodically use derivative instruments for risk management purposes to mitigate exposures to fluctuations in certain commodity prices and transmission congestion costs, and maintain risk policies that govern the use of such derivative instruments. As of June 30, 2013 and December 31, 2012, Alliant Energy’s, IPL’s and WPL’s derivative instruments were not designated as hedging instruments and included the following:
Risk management purpose | Type of instrument
Mitigate pricing volatility for: |
Electricity purchased to supply customers | Electric swap, swaption and physical purchase contracts (IPL and WPL)
Fuel used to supply natural gas-fired electric generating facilities | Natural gas swap and physical purchase contracts (IPL and WPL)
| Natural gas options (WPL)
Natural gas supplied to retail customers | Natural gas options and physical purchase contracts (IPL and WPL)
| Natural gas swap contracts (IPL)
Fuel used at coal-fired generating facilities | Coal physical purchase contract with volumetric optionality (WPL)
Optimize the value of natural gas pipeline capacity | Natural gas physical purchase and sale contracts (IPL and WPL)
| Natural gas swap contracts (IPL)
Manage transmission congestion costs | FTRs (IPL and WPL)
IPL’s and WPL’s swap, swaption, option and physical forward commodity contracts were non-exchange-based derivative instruments and were valued using indicative price quotations from a pricing vendor that provides daily exchange forward price settlements, from broker or dealer quotations, from market publications or from on-line exchanges. The indicative price quotations reflected the average of the bid-ask mid-point prices and were obtained from sources believed to provide the most liquid market for the commodity. IPL and WPL corroborated a portion of these indicative price quotations using quoted prices for similar assets or liabilities in active markets and categorized derivative instruments based on such indicative price quotations as Level 2. IPL’s and WPL’s commodity contracts that were valued using indicative price quotations based on significant assumptions such as seasonal or monthly shaping and indicative price quotations that could not be readily corroborated were categorized as Level 3. IPL’s and WPL’s swap, swaption, option and physical forward commodity contracts were predominately at liquid trading points. IPL’s and WPL’s FTRs were valued using monthly or annual auction shadow prices from relevant auctions and were categorized as Level 3. Refer to Note 11 for additional details of derivative assets and derivative liabilities. Level 3 inputs include observable and unobservable inputs used in the fair value measurements of IPL’s and WPL’s commodity contracts. The observable inputs are obtained from third-party pricing sources, counterparties and brokers and include bids, offers, historical transactions (including historical price differences between locations with both observable and unobservable prices) and executed trades. The significant unobservable inputs used in the fair value measurement of IPL’s and WPL’s commodity contracts are forecasted electricity, natural gas and coal prices, and the expected volatility of such prices. Significant changes in any of those inputs would result in a significantly lower or higher fair value measurement. Deferred proceeds (sales of receivables) - The fair value of IPL’s deferred proceeds related to its sales of receivables program was calculated each reporting date using the cost approach valuation technique. The fair value represents the carrying amount of receivables sold less the allowance for doubtful accounts associated with the receivables sold and cash proceeds received from the receivables sold due to the short-term nature of the collection period. These inputs were considered unobservable and deferred proceeds were categorized as Level 3. Deferred proceeds represent IPL’s maximum exposure to loss related to the receivables sold. Refer to Note 3(a) for additional information regarding deferred proceeds. Long-term debt (including current maturities) - For long-term debt instruments that are actively traded, the fair value was based upon quoted market prices for similar liabilities on each reporting date. For long-term debt instruments that are not actively traded, the fair value was based on a discounted cash flow methodology and utilizes assumptions of current market pricing curves at each reporting date. Refer to Note 8(b) for additional information regarding long-term debt. Cumulative preferred stock - As of June 30, 2013, the fair value of IPL’s 5.1% cumulative preferred stock was based on its closing market price quoted by the New York Stock Exchange. As of December 31, 2012, the fair value of IPL’s 8.375% cumulative preferred stock was based on its closing market price quoted by the New York Stock Exchange, the fair value of WPL’s 4.50% cumulative preferred stock was based on the closing market price quoted by the NYSE Amex LLC, and the fair value of WPL’s remaining preferred stock was calculated based on the market yield of similar securities. Refer to Note 7 for additional information regarding cumulative preferred stock. Items subject to fair value measurement disclosure requirements were as follows (in millions):
Alliant Energy | June 30, 2013 |  | December 31, 2012
| Fair |  | Level |  | Level |  | Level |  | Fair |  | Level |  | Level |  | Level
| Value |  | 1 |  | 2 |  | 3 |  | Value |  | 1 |  | 2 |  | 3
Assets: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Derivatives - commodity contracts |  | $60.5 |  |  |  | $— |  |  |  | $13.7 |  |  |  | $46.8 |  |  |  | $26.2 |  |  |  | $— |  |  |  | $4.8 |  |  |  | $21.4 |
Deferred proceeds | 69.3 |  |  | — |  |  | — |  |  | 69.3 |  |  | 66.8 |  |  | — |  |  | — |  |  | 66.8 |
Capitalization and liabilities: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Long-term debt (including current maturities) | 3,619.5 |  |  | — |  |  | 3,619.1 |  |  | 0.4 |  |  | 3,860.5 |  |  | — |  |  | 3,860.0 |  |  | 0.5 |
Cumulative preferred stock | 188.4 |  |  | 188.4 |  |  | — |  |  | — |  |  | 212.6 |  |  | 162.3 |  |  | 50.3 |  |  | — |
Derivatives - commodity contracts | 37.1 |  |  | — |  |  | 32.8 |  |  | 4.3 |  |  | 40.4 |  |  | — |  |  | 30.9 |  |  | 9.5 |
IPL | June 30, 2013 |  | December 31, 2012
| Fair |  | Level |  | Level |  | Level |  | Fair |  | Level |  | Level |  | Level
| Value |  | 1 |  | 2 |  | 3 |  | Value |  | 1 |  | 2 |  | 3
Assets: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Derivatives - commodity contracts |  | $45.1 |  |  |  | $— |  |  |  | $3.0 |  |  |  | $42.1 |  |  |  | $17.5 |  |  |  | $— |  |  |  | $3.1 |  |  |  | $14.4 |
Deferred proceeds | 69.3 |  |  | — |  |  | — |  |  | 69.3 |  |  | 66.8 |  |  | — |  |  | — |  |  | 66.8 |
Capitalization and liabilities: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Long-term debt | 1,586.8 |  |  | — |  |  | 1,586.8 |  |  | — |  |  | 1,679.9 |  |  | — |  |  | 1,679.9 |  |  | — |
Cumulative preferred stock | 188.4 |  |  | 188.4 |  |  | — |  |  | — |  |  | 151.8 |  |  | 151.8 |  |  | — |  |  | — |
Derivatives - commodity contracts | 9.7 |  |  | — |  |  | 8.2 |  |  | 1.5 |  |  | 16.1 |  |  | — |  |  | 14.2 |  |  | 1.9 |
WPL | June 30, 2013 |  | December 31, 2012
| Fair |  | Level |  | Level |  | Level |  | Fair |  | Level |  | Level |  | Level
| Value |  | 1 |  | 2 |  | 3 |  | Value |  | 1 |  | 2 |  | 3
Assets: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Derivatives - commodity contracts |  | $15.4 |  |  |  | $— |  |  |  | $10.7 |  |  |  | $4.7 |  |  |  | $8.7 |  |  |  | $— |  |  |  | $1.7 |  |  |  | $7.0 |
Capitalization and liabilities: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Long-term debt | 1,572.1 |  |  | — |  |  | 1,572.1 |  |  | — |  |  | 1,713.3 |  |  | — |  |  | 1,713.3 |  |  | — |
Cumulative preferred stock | — |  |  | — |  |  | — |  |  | — |  |  | 60.8 |  |  | 10.5 |  |  | 50.3 |  |  | — |
Derivatives - commodity contracts | 27.4 |  |  | — |  |  | 24.6 |  |  | 2.8 |  |  | 24.3 |  |  | — |  |  | 16.7 |  |  | 7.6 |
Alliant Energy, IPL and WPL generally record gains and losses from IPL’s and WPL’s derivative instruments with offsets to regulatory assets or regulatory liabilities, based on their fuel and natural gas cost recovery mechanisms, as well as other specific regulatory authorizations. Based on these recovery mechanisms, the changes in the fair value of derivative liabilities resulted in comparable changes to regulatory assets, and the changes in the fair value of derivative assets resulted in comparable changes to regulatory liabilities on the Condensed Consolidated Balance Sheets. Information for fair value measurements using significant unobservable inputs (Level 3 inputs) was as follows (in millions):
Alliant Energy | Commodity Contract Derivative |  |
| Assets and (Liabilities), net |  | Deferred Proceeds
Three Months Ended June 30 | 2013 |  | 2012 |  | 2013 |  | 2012
Beginning balance, April 1 |  | $4.9 |  |  |  | ($15.1 | ) |  |  | $122.1 |  |  |  | $32.9 |
Total net gains (losses) (realized/unrealized) included in changes in net assets (a) | (1.2 | ) |  | 3.0 |  |  | — |  |  | — |
Transfers into Level 3 (b) | — |  |  | (0.6 | ) |  | — |  |  | — |
Transfers out of Level 3 (c) | — |  |  | 0.4 |  |  | — |  |  | — |
Purchases | 50.9 |  |  | 35.8 |  |  | — |  |  | — |
Settlements (d) | (12.1 | ) |  | (4.7 | ) |  | (52.8 | ) |  | 48.8 |
Ending balance, June 30 |  | $42.5 |  |  |  | $18.8 |  |  |  | $69.3 |  |  |  | $81.7 |
The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at June 30 (a) |  | ($1.2 | ) |  |  | $3.5 |  |  |  | $— |  |  |  | $— |
Alliant Energy | Commodity Contract Derivative |  |
| Assets and (Liabilities), net |  | Deferred Proceeds
Six Months Ended June 30 | 2013 |  | 2012 |  | 2013 |  | 2012
Beginning balance, January 1 |  | $11.9 |  |  |  | ($0.9 | ) |  |  | $66.8 |  |  |  | $53.7 |
Total net losses (realized/unrealized) included in changes in net assets (a) | (3.0 | ) |  | (6.3 | ) |  | — |  |  | — |
Transfers into Level 3 (b) | — |  |  | (2.3 | ) |  | — |  |  | — |
Transfers out of Level 3 (c) | 3.6 |  |  | 0.3 |  |  | — |  |  | — |
Purchases | 50.9 |  |  | 35.8 |  |  | — |  |  | — |
Settlements (d) | (20.9 | ) |  | (7.8 | ) |  | 2.5 |  |  | 28.0 |
Ending balance, June 30 |  | $42.5 |  |  |  | $18.8 |  |  |  | $69.3 |  |  |  | $81.7 |
The amount of total net losses for the period included in changes in net assets attributable to the change in unrealized losses relating to assets and liabilities held at June 30 (a) |  | ($3.0 | ) |  |  | ($4.1 | ) |  |  | $— |  |  |  | $— |
IPL | Commodity Contract Derivative |  |
| Assets and (Liabilities), net |  | Deferred Proceeds
Three Months Ended June 30 | 2013 |  | 2012 |  | 2013 |  | 2012
Beginning balance, April 1 |  | $4.3 |  |  |  | ($11.4 | ) |  |  | $122.1 |  |  |  | $32.9 |
Total net gains (losses) (realized/unrealized) included in changes in net assets (a) | (0.1 | ) |  | 2.9 |  |  | — |  |  | — |
Transfers into Level 3 (b) | — |  |  | (0.2 | ) |  | — |  |  | — |
Purchases | 46.1 |  |  | 26.8 |  |  | — |  |  | — |
Settlements (d) | (9.7 | ) |  | (4.0 | ) |  | (52.8 | ) |  | 48.8 |
Ending balance, June 30 |  | $40.6 |  |  |  | $14.1 |  |  |  | $69.3 |  |  |  | $81.7 |
The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at June 30 (a) |  | ($0.1 | ) |  |  | $3.6 |  |  |  | $— |  |  |  | $— |
IPL | Commodity Contract Derivative |  |
| Assets and (Liabilities), net |  | Deferred Proceeds
Six Months Ended June 30 | 2013 |  | 2012 |  | 2013 |  | 2012
Beginning balance, January 1 |  | $12.5 |  |  |  | $4.3 |  |  |  | $66.8 |  |  |  | $53.7 |
Total net losses (realized/unrealized) included in changes in net assets (a) | (3.0 | ) |  | (9.4 | ) |  | — |  |  | — |
Transfers into Level 3 (b) | — |  |  | (1.3 | ) |  | — |  |  | — |
Transfers out of Level 3 (c) | 1.1 |  |  | — |  |  | — |  |  | — |
Purchases | 46.1 |  |  | 26.8 |  |  | — |  |  | — |
Settlements (d) | (16.1 | ) |  | (6.3 | ) |  | 2.5 |  |  | 28.0 |
Ending balance, June 30 |  | $40.6 |  |  |  | $14.1 |  |  |  | $69.3 |  |  |  | $81.7 |
The amount of total net losses for the period included in changes in net assets attributable to the change in unrealized losses relating to assets and liabilities held at June 30 (a) |  | ($3.0 | ) |  |  | ($7.0 | ) |  |  | $— |  |  |  | $— |
WPL | Commodity Contract Derivative
| Assets and (Liabilities), net
Three Months Ended June 30 | 2013 |  | 2012
Beginning balance, April 1 |  | $0.6 |  |  |  | ($3.7 | )
Total net gains (losses) (realized/unrealized) included in changes in net assets (a) | (1.1 | ) |  | 0.1 |
Transfers into Level 3 (b) | — |  |  | (0.4 | )
Transfers out of Level 3 (c) | — |  |  | 0.4 |
Purchases | 4.8 |  |  | 9.0 |
Settlements | (2.4 | ) |  | (0.7 | )
Ending balance, June 30 |  | $1.9 |  |  |  | $4.7 |
The amount of total net losses for the period included in changes in net assets attributable to the change in unrealized losses relating to assets and liabilities held at June 30 (a) |  | ($1.1 | ) |  |  | ($0.1 | )
WPL | Commodity Contract Derivative
| Assets and (Liabilities), net
Six Months Ended June 30 | 2013 |  | 2012
Beginning balance, January 1 |  | ($0.6 | ) |  |  | ($5.2 | )
Total net gains (realized/unrealized) included in changes in net assets (a) | — |  |  | 3.1 |
Transfers into Level 3 (b) | — |  |  | (1.0 | )
Transfers out of Level 3 (c) | 2.5 |  |  | 0.3 |
Purchases | 4.8 |  |  | 9.0 |
Settlements | (4.8 | ) |  | (1.5 | )
Ending balance, June 30 |  | $1.9 |  |  |  | $4.7 |
The amount of total net gains for the period included in changes in net assets attributable to the change in unrealized gains relating to assets and liabilities held at June 30 (a) |  | $— |  |  |  | $2.9 |
(a) | Gains and losses related to derivative assets and derivative liabilities are recorded in “Regulatory assets” and “Regulatory liabilities” on the Condensed Consolidated Balance Sheets.
(b) | Markets for similar assets and liabilities became inactive and observable market inputs became unavailable for transfers into Level 3. The transfers were valued as of the beginning of the period.
(c) | Observable market inputs became available for certain commodity contracts previously classified as Level 3 for transfers out of Level 3. The transfers were valued as of the beginning of the period.
(d) | Settlements related to deferred proceeds are due to the change in the carrying amount of receivables sold less the allowance for doubtful accounts associated with the receivables sold and cash proceeds received from the receivables sold.
Commodity Contracts - As of June 30, 2013, the fair value of Alliant Energy’s, IPL’s and WPL’s electric, natural gas and coal commodity contracts categorized as Level 3, excluding FTRs, were recognized as net derivative liabilities of $2.7 million, $0.4 million and $2.3 million, respectively. As of June 30, 2013, Alliant Energy’s, IPL’s and WPL’s FTRs classified as Level 3 were recognized as net derivative assets of $45.2 million, $41.0 million and $4.2 million, respectively.
WPL [Member] |
Fair Value Measurements | FAIR VALUE MEASUREMENTS Fair Value of Financial Instruments - The carrying amounts of Alliant Energy’s, IPL’s and WPL’s current assets and current liabilities approximate fair value because of the short maturity of such financial instruments. Carrying amounts and the related estimated fair values of other financial instruments were as follows (in millions):
| Alliant Energy |  | IPL |  | WPL
| Carrying Amount |  | Fair Value |  | Carrying Amount |  | Fair Value |  | Carrying Amount |  | Fair Value
June 30, 2013 |  |  |  |  |  |  |  |  |  |  |
Assets: |  |  |  |  |  |  |  |  |  |  |
Derivative assets (Note 11) |  | $60.5 |  |  |  | $60.5 |  |  |  | $45.1 |  |  |  | $45.1 |  |  |  | $15.4 |  |  |  | $15.4 |
Deferred proceeds (sales of receivables) (Note 3(a)) | 69.3 |  |  | 69.3 |  |  | 69.3 |  |  | 69.3 |  |  | — |  |  | — |
Capitalization and liabilities: |  |  |  |  |  |  |  |  |  |  |
Long-term debt (including current maturities) (Note 8(b)) | 3,142.9 |  |  | 3,619.5 |  |  | 1,364.7 |  |  | 1,586.8 |  |  | 1,331.9 |  |  | 1,572.1 |
Cumulative preferred stock (Note 7) | 200.0 |  |  | 188.4 |  |  | 200.0 |  |  | 188.4 |  |  | — |  |  | — |
Derivative liabilities (Note 11) | 37.1 |  |  | 37.1 |  |  | 9.7 |  |  | 9.7 |  |  | 27.4 |  |  | 27.4 |
| Alliant Energy |  | IPL |  | WPL
| Carrying Amount |  | Fair Value |  | Carrying Amount |  | Fair Value |  | Carrying Amount |  | Fair Value
December 31, 2012 |  |  |  |  |  |  |  |  |  |  |
Assets: |  |  |  |  |  |  |  |  |  |  |
Derivative assets (Note 11) |  | $26.2 |  |  |  | $26.2 |  |  |  | $17.5 |  |  |  | $17.5 |  |  |  | $8.7 |  |  |  | $8.7 |
Deferred proceeds (sales of receivables) (Note 3(a)) | 66.8 |  |  | 66.8 |  |  | 66.8 |  |  | 66.8 |  |  | — |  |  | — |
Capitalization and liabilities: |  |  |  |  |  |  |  |  |  |  |
Long-term debt (including current maturities) (Note 8(b)) | 3,138.1 |  |  | 3,860.5 |  |  | 1,359.5 |  |  | 1,679.9 |  |  | 1,331.5 |  |  | 1,713.3 |
Cumulative preferred stock (Note 7) | 205.1 |  |  | 212.6 |  |  | 145.1 |  |  | 151.8 |  |  | 60.0 |  |  | 60.8 |
Derivative liabilities (Note 11) | 40.4 |  |  | 40.4 |  |  | 16.1 |  |  | 16.1 |  |  | 24.3 |  |  | 24.3 |
Valuation Hierarchy - Fair value measurement accounting establishes a fair value hierarchy that prioritizes the inputs to valuation techniques used to measure fair value. The three levels of the fair value hierarchy and examples of each are as follows: Level 1 - Pricing inputs are quoted prices available in active markets for identical assets or liabilities as of the reporting date. As of June 30, 2013, Level 1 items included IPL’s 5.1% cumulative preferred stock. As of December 31, 2012, Level 1 items included IPL’s 8.375% cumulative preferred stock and WPL’s 4.50% cumulative preferred stock. Level 2 - Pricing inputs are quoted prices for similar assets or liabilities in active markets or quoted prices for identical or similar assets or liabilities in markets that are not active as of the reporting date. As of June 30, 2013 and December 31, 2012, Level 2 items included certain of IPL’s and WPL’s non-exchange traded commodity contracts and substantially all of the long-term debt instruments. Level 2 items as of December 31, 2012 also included the remainder of WPL’s cumulative preferred stock. Level 3 - Pricing inputs are unobservable inputs for assets or liabilities for which little or no market data exist and require significant management judgment or estimation. As of June 30, 2013 and December 31, 2012, Level 3 items included IPL’s deferred proceeds, and IPL’s and WPL’s financial transmission rights (FTRs) and certain non-exchange traded commodity contracts. The fair value hierarchy gives the highest priority to quoted prices in active markets (Level 1) and the lowest priority to unobservable data (Level 3). In some cases, the inputs used to measure fair value might fall in different levels of the fair value hierarchy. The lowest level input that is significant to a fair value measurement in its entirety determines the applicable level in the fair value hierarchy. Assessing the significance of a particular input to the fair value measurement in its entirety requires judgment, considering factors specific to the asset or liability. Valuation Techniques - Derivative assets and derivative liabilities - Alliant Energy, IPL and WPL periodically use derivative instruments for risk management purposes to mitigate exposures to fluctuations in certain commodity prices and transmission congestion costs, and maintain risk policies that govern the use of such derivative instruments. As of June 30, 2013 and December 31, 2012, Alliant Energy’s, IPL’s and WPL’s derivative instruments were not designated as hedging instruments and included the following:
Risk management purpose | Type of instrument
Mitigate pricing volatility for: |
Electricity purchased to supply customers | Electric swap, swaption and physical purchase contracts (IPL and WPL)
Fuel used to supply natural gas-fired electric generating facilities | Natural gas swap and physical purchase contracts (IPL and WPL)
| Natural gas options (WPL)
Natural gas supplied to retail customers | Natural gas options and physical purchase contracts (IPL and WPL)
| Natural gas swap contracts (IPL)
Fuel used at coal-fired generating facilities | Coal physical purchase contract with volumetric optionality (WPL)
Optimize the value of natural gas pipeline capacity | Natural gas physical purchase and sale contracts (IPL and WPL)
| Natural gas swap contracts (IPL)
Manage transmission congestion costs | FTRs (IPL and WPL)
IPL’s and WPL’s swap, swaption, option and physical forward commodity contracts were non-exchange-based derivative instruments and were valued using indicative price quotations from a pricing vendor that provides daily exchange forward price settlements, from broker or dealer quotations, from market publications or from on-line exchanges. The indicative price quotations reflected the average of the bid-ask mid-point prices and were obtained from sources believed to provide the most liquid market for the commodity. IPL and WPL corroborated a portion of these indicative price quotations using quoted prices for similar assets or liabilities in active markets and categorized derivative instruments based on such indicative price quotations as Level 2. IPL’s and WPL’s commodity contracts that were valued using indicative price quotations based on significant assumptions such as seasonal or monthly shaping and indicative price quotations that could not be readily corroborated were categorized as Level 3. IPL’s and WPL’s swap, swaption, option and physical forward commodity contracts were predominately at liquid trading points. IPL’s and WPL’s FTRs were valued using monthly or annual auction shadow prices from relevant auctions and were categorized as Level 3. Refer to Note 11 for additional details of derivative assets and derivative liabilities. Level 3 inputs include observable and unobservable inputs used in the fair value measurements of IPL’s and WPL’s commodity contracts. The observable inputs are obtained from third-party pricing sources, counterparties and brokers and include bids, offers, historical transactions (including historical price differences between locations with both observable and unobservable prices) and executed trades. The significant unobservable inputs used in the fair value measurement of IPL’s and WPL’s commodity contracts are forecasted electricity, natural gas and coal prices, and the expected volatility of such prices. Significant changes in any of those inputs would result in a significantly lower or higher fair value measurement. Deferred proceeds (sales of receivables) - The fair value of IPL’s deferred proceeds related to its sales of receivables program was calculated each reporting date using the cost approach valuation technique. The fair value represents the carrying amount of receivables sold less the allowance for doubtful accounts associated with the receivables sold and cash proceeds received from the receivables sold due to the short-term nature of the collection period. These inputs were considered unobservable and deferred proceeds were categorized as Level 3. Deferred proceeds represent IPL’s maximum exposure to loss related to the receivables sold. Refer to Note 3(a) for additional information regarding deferred proceeds. Long-term debt (including current maturities) - For long-term debt instruments that are actively traded, the fair value was based upon quoted market prices for similar liabilities on each reporting date. For long-term debt instruments that are not actively traded, the fair value was based on a discounted cash flow methodology and utilizes assumptions of current market pricing curves at each reporting date. Refer to Note 8(b) for additional information regarding long-term debt. Cumulative preferred stock - As of June 30, 2013, the fair value of IPL’s 5.1% cumulative preferred stock was based on its closing market price quoted by the New York Stock Exchange. As of December 31, 2012, the fair value of IPL’s 8.375% cumulative preferred stock was based on its closing market price quoted by the New York Stock Exchange, the fair value of WPL’s 4.50% cumulative preferred stock was based on the closing market price quoted by the NYSE Amex LLC, and the fair value of WPL’s remaining preferred stock was calculated based on the market yield of similar securities. Refer to Note 7 for additional information regarding cumulative preferred stock. Items subject to fair value measurement disclosure requirements were as follows (in millions):
Alliant Energy | June 30, 2013 |  | December 31, 2012
| Fair |  | Level |  | Level |  | Level |  | Fair |  | Level |  | Level |  | Level
| Value |  | 1 |  | 2 |  | 3 |  | Value |  | 1 |  | 2 |  | 3
Assets: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Derivatives - commodity contracts |  | $60.5 |  |  |  | $— |  |  |  | $13.7 |  |  |  | $46.8 |  |  |  | $26.2 |  |  |  | $— |  |  |  | $4.8 |  |  |  | $21.4 |
Deferred proceeds | 69.3 |  |  | — |  |  | — |  |  | 69.3 |  |  | 66.8 |  |  | — |  |  | — |  |  | 66.8 |
Capitalization and liabilities: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Long-term debt (including current maturities) | 3,619.5 |  |  | — |  |  | 3,619.1 |  |  | 0.4 |  |  | 3,860.5 |  |  | — |  |  | 3,860.0 |  |  | 0.5 |
Cumulative preferred stock | 188.4 |  |  | 188.4 |  |  | — |  |  | — |  |  | 212.6 |  |  | 162.3 |  |  | 50.3 |  |  | — |
Derivatives - commodity contracts | 37.1 |  |  | — |  |  | 32.8 |  |  | 4.3 |  |  | 40.4 |  |  | — |  |  | 30.9 |  |  | 9.5 |
IPL | June 30, 2013 |  | December 31, 2012
| Fair |  | Level |  | Level |  | Level |  | Fair |  | Level |  | Level |  | Level
| Value |  | 1 |  | 2 |  | 3 |  | Value |  | 1 |  | 2 |  | 3
Assets: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Derivatives - commodity contracts |  | $45.1 |  |  |  | $— |  |  |  | $3.0 |  |  |  | $42.1 |  |  |  | $17.5 |  |  |  | $— |  |  |  | $3.1 |  |  |  | $14.4 |
Deferred proceeds | 69.3 |  |  | — |  |  | — |  |  | 69.3 |  |  | 66.8 |  |  | — |  |  | — |  |  | 66.8 |
Capitalization and liabilities: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Long-term debt | 1,586.8 |  |  | — |  |  | 1,586.8 |  |  | — |  |  | 1,679.9 |  |  | — |  |  | 1,679.9 |  |  | — |
Cumulative preferred stock | 188.4 |  |  | 188.4 |  |  | — |  |  | — |  |  | 151.8 |  |  | 151.8 |  |  | — |  |  | — |
Derivatives - commodity contracts | 9.7 |  |  | — |  |  | 8.2 |  |  | 1.5 |  |  | 16.1 |  |  | — |  |  | 14.2 |  |  | 1.9 |
WPL | June 30, 2013 |  | December 31, 2012
| Fair |  | Level |  | Level |  | Level |  | Fair |  | Level |  | Level |  | Level
| Value |  | 1 |  | 2 |  | 3 |  | Value |  | 1 |  | 2 |  | 3
Assets: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Derivatives - commodity contracts |  | $15.4 |  |  |  | $— |  |  |  | $10.7 |  |  |  | $4.7 |  |  |  | $8.7 |  |  |  | $— |  |  |  | $1.7 |  |  |  | $7.0 |
Capitalization and liabilities: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Long-term debt | 1,572.1 |  |  | — |  |  | 1,572.1 |  |  | — |  |  | 1,713.3 |  |  | — |  |  | 1,713.3 |  |  | — |
Cumulative preferred stock | — |  |  | — |  |  | — |  |  | — |  |  | 60.8 |  |  | 10.5 |  |  | 50.3 |  |  | — |
Derivatives - commodity contracts | 27.4 |  |  | — |  |  | 24.6 |  |  | 2.8 |  |  | 24.3 |  |  | — |  |  | 16.7 |  |  | 7.6 |
Alliant Energy, IPL and WPL generally record gains and losses from IPL’s and WPL’s derivative instruments with offsets to regulatory assets or regulatory liabilities, based on their fuel and natural gas cost recovery mechanisms, as well as other specific regulatory authorizations. Based on these recovery mechanisms, the changes in the fair value of derivative liabilities resulted in comparable changes to regulatory assets, and the changes in the fair value of derivative assets resulted in comparable changes to regulatory liabilities on the Condensed Consolidated Balance Sheets. Information for fair value measurements using significant unobservable inputs (Level 3 inputs) was as follows (in millions):
Alliant Energy | Commodity Contract Derivative |  |
| Assets and (Liabilities), net |  | Deferred Proceeds
Three Months Ended June 30 | 2013 |  | 2012 |  | 2013 |  | 2012
Beginning balance, April 1 |  | $4.9 |  |  |  | ($15.1 | ) |  |  | $122.1 |  |  |  | $32.9 |
Total net gains (losses) (realized/unrealized) included in changes in net assets (a) | (1.2 | ) |  | 3.0 |  |  | — |  |  | — |
Transfers into Level 3 (b) | — |  |  | (0.6 | ) |  | — |  |  | — |
Transfers out of Level 3 (c) | — |  |  | 0.4 |  |  | — |  |  | — |
Purchases | 50.9 |  |  | 35.8 |  |  | — |  |  | — |
Settlements (d) | (12.1 | ) |  | (4.7 | ) |  | (52.8 | ) |  | 48.8 |
Ending balance, June 30 |  | $42.5 |  |  |  | $18.8 |  |  |  | $69.3 |  |  |  | $81.7 |
The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at June 30 (a) |  | ($1.2 | ) |  |  | $3.5 |  |  |  | $— |  |  |  | $— |
Alliant Energy | Commodity Contract Derivative |  |
| Assets and (Liabilities), net |  | Deferred Proceeds
Six Months Ended June 30 | 2013 |  | 2012 |  | 2013 |  | 2012
Beginning balance, January 1 |  | $11.9 |  |  |  | ($0.9 | ) |  |  | $66.8 |  |  |  | $53.7 |
Total net losses (realized/unrealized) included in changes in net assets (a) | (3.0 | ) |  | (6.3 | ) |  | — |  |  | — |
Transfers into Level 3 (b) | — |  |  | (2.3 | ) |  | — |  |  | — |
Transfers out of Level 3 (c) | 3.6 |  |  | 0.3 |  |  | — |  |  | — |
Purchases | 50.9 |  |  | 35.8 |  |  | — |  |  | — |
Settlements (d) | (20.9 | ) |  | (7.8 | ) |  | 2.5 |  |  | 28.0 |
Ending balance, June 30 |  | $42.5 |  |  |  | $18.8 |  |  |  | $69.3 |  |  |  | $81.7 |
The amount of total net losses for the period included in changes in net assets attributable to the change in unrealized losses relating to assets and liabilities held at June 30 (a) |  | ($3.0 | ) |  |  | ($4.1 | ) |  |  | $— |  |  |  | $— |
IPL | Commodity Contract Derivative |  |
| Assets and (Liabilities), net |  | Deferred Proceeds
Three Months Ended June 30 | 2013 |  | 2012 |  | 2013 |  | 2012
Beginning balance, April 1 |  | $4.3 |  |  |  | ($11.4 | ) |  |  | $122.1 |  |  |  | $32.9 |
Total net gains (losses) (realized/unrealized) included in changes in net assets (a) | (0.1 | ) |  | 2.9 |  |  | — |  |  | — |
Transfers into Level 3 (b) | — |  |  | (0.2 | ) |  | — |  |  | — |
Purchases | 46.1 |  |  | 26.8 |  |  | — |  |  | — |
Settlements (d) | (9.7 | ) |  | (4.0 | ) |  | (52.8 | ) |  | 48.8 |
Ending balance, June 30 |  | $40.6 |  |  |  | $14.1 |  |  |  | $69.3 |  |  |  | $81.7 |
The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at June 30 (a) |  | ($0.1 | ) |  |  | $3.6 |  |  |  | $— |  |  |  | $— |
IPL | Commodity Contract Derivative |  |
| Assets and (Liabilities), net |  | Deferred Proceeds
Six Months Ended June 30 | 2013 |  | 2012 |  | 2013 |  | 2012
Beginning balance, January 1 |  | $12.5 |  |  |  | $4.3 |  |  |  | $66.8 |  |  |  | $53.7 |
Total net losses (realized/unrealized) included in changes in net assets (a) | (3.0 | ) |  | (9.4 | ) |  | — |  |  | — |
Transfers into Level 3 (b) | — |  |  | (1.3 | ) |  | — |  |  | — |
Transfers out of Level 3 (c) | 1.1 |  |  | — |  |  | — |  |  | — |
Purchases | 46.1 |  |  | 26.8 |  |  | — |  |  | — |
Settlements (d) | (16.1 | ) |  | (6.3 | ) |  | 2.5 |  |  | 28.0 |
Ending balance, June 30 |  | $40.6 |  |  |  | $14.1 |  |  |  | $69.3 |  |  |  | $81.7 |
The amount of total net losses for the period included in changes in net assets attributable to the change in unrealized losses relating to assets and liabilities held at June 30 (a) |  | ($3.0 | ) |  |  | ($7.0 | ) |  |  | $— |  |  |  | $— |
WPL | Commodity Contract Derivative
| Assets and (Liabilities), net
Three Months Ended June 30 | 2013 |  | 2012
Beginning balance, April 1 |  | $0.6 |  |  |  | ($3.7 | )
Total net gains (losses) (realized/unrealized) included in changes in net assets (a) | (1.1 | ) |  | 0.1 |
Transfers into Level 3 (b) | — |  |  | (0.4 | )
Transfers out of Level 3 (c) | — |  |  | 0.4 |
Purchases | 4.8 |  |  | 9.0 |
Settlements | (2.4 | ) |  | (0.7 | )
Ending balance, June 30 |  | $1.9 |  |  |  | $4.7 |
The amount of total net losses for the period included in changes in net assets attributable to the change in unrealized losses relating to assets and liabilities held at June 30 (a) |  | ($1.1 | ) |  |  | ($0.1 | )
WPL | Commodity Contract Derivative
| Assets and (Liabilities), net
Six Months Ended June 30 | 2013 |  | 2012
Beginning balance, January 1 |  | ($0.6 | ) |  |  | ($5.2 | )
Total net gains (realized/unrealized) included in changes in net assets (a) | — |  |  | 3.1 |
Transfers into Level 3 (b) | — |  |  | (1.0 | )
Transfers out of Level 3 (c) | 2.5 |  |  | 0.3 |
Purchases | 4.8 |  |  | 9.0 |
Settlements | (4.8 | ) |  | (1.5 | )
Ending balance, June 30 |  | $1.9 |  |  |  | $4.7 |
The amount of total net gains for the period included in changes in net assets attributable to the change in unrealized gains relating to assets and liabilities held at June 30 (a) |  | $— |  |  |  | $2.9 |
(a) | Gains and losses related to derivative assets and derivative liabilities are recorded in “Regulatory assets” and “Regulatory liabilities” on the Condensed Consolidated Balance Sheets.
(b) | Markets for similar assets and liabilities became inactive and observable market inputs became unavailable for transfers into Level 3. The transfers were valued as of the beginning of the period.
(c) | Observable market inputs became available for certain commodity contracts previously classified as Level 3 for transfers out of Level 3. The transfers were valued as of the beginning of the period.
(d) | Settlements related to deferred proceeds are due to the change in the carrying amount of receivables sold less the allowance for doubtful accounts associated with the receivables sold and cash proceeds received from the receivables sold.
Commodity Contracts - As of June 30, 2013, the fair value of Alliant Energy’s, IPL’s and WPL’s electric, natural gas and coal commodity contracts categorized as Level 3, excluding FTRs, were recognized as net derivative liabilities of $2.7 million, $0.4 million and $2.3 million, respectively. As of June 30, 2013, Alliant Energy’s, IPL’s and WPL’s FTRs classified as Level 3 were recognized as net derivative assets of $45.2 million, $41.0 million and $4.2 million, respectively.

X
- Definition The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 107 -Paragraph 15A -Subparagraph a-d -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 107 -Paragraph 15C, 15D -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 107 -Paragraph 3, 10, 14, 15 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 157 -Paragraph 32, 33, 34 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. 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Reference 7: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 10 -URI http://asc.fasb.org/extlink&oid=7491637&loc=d3e13433-108611 Reference 8: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 28 -URI http://asc.fasb.org/extlink&oid=6957238&loc=d3e14064-108612 Reference 9: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=7578670&loc=d3e19207-110258 Reference 10: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 30 -URI http://asc.fasb.org/extlink&oid=6957238&loc=d3e14172-108612 Reference 11: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 16 -URI http://asc.fasb.org/extlink&oid=7491637&loc=d3e13504-108611 Reference 12: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 107 -Paragraph 15B -Subparagraph a, b -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. 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