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Redeemable Preferred Stock	3 Months Ended
Redeemable Preferred Stock	Mar. 31, 2014
Redeemable Preferred Stock	REDEEMABLE PREFERRED STOCK IPL - In March 2013, IPL redeemed all 6,000,000 outstanding shares of its 8.375% cumulative preferred stock for $150 million plus accrued and unpaid dividends to the redemption date. Alliant Energy and IPL recorded a $5 million charge during the three months ended March 31, 2013 related to this transaction in “Preferred dividend requirements” in their income statements. WPL - In March 2013, WPL redeemed all 1,049,225 outstanding shares of its 4.40% through 6.50% cumulative preferred stock for $61 million plus accrued and unpaid dividends to the redemption date. Alliant Energy and WPL recorded a $1 million charge during the three months ended March 31, 2013 related to this transaction in “Preferred dividend requirements” in their income statements. Refer to Note 11 for information on the fair value of cumulative preferred stock.
IPL [Member]
Redeemable Preferred Stock	REDEEMABLE PREFERRED STOCK IPL - In March 2013, IPL redeemed all 6,000,000 outstanding shares of its 8.375% cumulative preferred stock for $150 million plus accrued and unpaid dividends to the redemption date. Alliant Energy and IPL recorded a $5 million charge during the three months ended March 31, 2013 related to this transaction in “Preferred dividend requirements” in their income statements. WPL - In March 2013, WPL redeemed all 1,049,225 outstanding shares of its 4.40% through 6.50% cumulative preferred stock for $61 million plus accrued and unpaid dividends to the redemption date. Alliant Energy and WPL recorded a $1 million charge during the three months ended March 31, 2013 related to this transaction in “Preferred dividend requirements” in their income statements. Refer to Note 11 for information on the fair value of cumulative preferred stock.
WPL [Member]
Redeemable Preferred Stock	REDEEMABLE PREFERRED STOCK IPL - In March 2013, IPL redeemed all 6,000,000 outstanding shares of its 8.375% cumulative preferred stock for $150 million plus accrued and unpaid dividends to the redemption date. Alliant Energy and IPL recorded a $5 million charge during the three months ended March 31, 2013 related to this transaction in “Preferred dividend requirements” in their income statements. WPL - In March 2013, WPL redeemed all 1,049,225 outstanding shares of its 4.40% through 6.50% cumulative preferred stock for $61 million plus accrued and unpaid dividends to the redemption date. Alliant Energy and WPL recorded a $1 million charge during the three months ended March 31, 2013 related to this transaction in “Preferred dividend requirements” in their income statements. Refer to Note 11 for information on the fair value of cumulative preferred stock.