Regulatory Matters	3 Months Ended
Mar. 31, 2017
Regulated Operations [Abstract]
Regulatory Matters	REGULATORY MATTERS In March 2016, the IURC issued the 2016 Rate Order authorizing IPL to increase its basic rates and charges by $30.8 million annually. The order also authorized IPL to collect, over a ten year period, $117.7 million of previously deferred regulatory assets related to IPL’s participation in the regional transmission organization known as MISO. Such deferred costs will be amortized to expense over ten years. Accordingly, $11.8 million of IPL’s long-term MISO regulatory asset is included within current regulatory assets on the accompanying Unaudited Condensed Consolidated Balance Sheets. The rate order also authorized an increase in IPL’s depreciation rates of $24.3 million annually compared to the twelve months ended June 30, 2014, which is the period upon which the rate increase was calculated. IPL also received approval to implement three new rate riders for current recovery from customers of ongoing MISO costs and capacity costs, and for sharing with customers 50% of wholesale sales margins above and below the established annual benchmark of $6.3 million. Additionally, the capacity rider provides that IPL will share with customers 50% of any capacity sales. The order approved recovery of IPL’s pension expenses and a return on IPL’s discretionary pension fundings. While the IURC noted in the order that they found IPL’s Service Company cost allocations to be reasonable, IPL was directed to request the FERC to review its Service Company allocations. Such review is currently underway. The IURC also closed their investigation into IPL’s underground network. Some of the intervening parties in the IURC rate case filed petitions for reconsideration of the IURC’s March 2016 order with respect to certain issues. These petitions were subsequently denied by the IURC. In addition, certain intervening parties have filed notices of appeal of the order. On April 5, 2017, the Indiana Court of Appeals affirmed the IURC’s March 2016 order. In May 2014, IPL received an order from the IURC granting approval to build a 644 to 685 MW CCGT at Eagle Valley. The costs to build and operate the CCGT, other than fuel costs, will not be recoverable by IPL through rates until the conclusion of a base rate case proceeding with the IURC after construction is completed. On December 22, 2016, IPL filed a petition with the IURC for authority to increase its basic rates and charges primarily to recover the cost of the new CCGT. The CCGT was previously expected to be completed in the first half of 2017, but is now expected to be completed in the first half of 2018. To address this change, on February 24, 2017, IPL filed a motion to withdraw the case without prejudice or alternatively amend the petition and case-in-chief at a later date. On March 15, 2017, the IURC dismissed the rate case without prejudice. IPL will file a new base rate case with the IURC to coincide with the completion of the CCGT.

REGULATORY MATTERS

In March 2016, the IURC issued the 2016 Rate Order authorizing IPL to increase its basic rates and charges by $30.8 million annually. The order also authorized IPL to collect, over a ten year period, $117.7 million of previously deferred regulatory assets related to IPL’s participation in the regional transmission organization known as MISO. Such deferred costs will be amortized to expense over ten years. Accordingly, $11.8 million of IPL’s long-term MISO regulatory asset is included within current regulatory assets on the accompanying Unaudited Condensed Consolidated Balance Sheets. The rate order also authorized an increase in IPL’s depreciation rates of $24.3 million annually compared to the twelve months ended June 30, 2014, which is the period upon which the rate increase was calculated. IPL also received approval to implement three new rate riders for current recovery from customers of ongoing MISO costs and capacity costs, and for sharing with customers 50% of wholesale sales margins above and below the established annual benchmark of $6.3 million. Additionally, the capacity rider provides that IPL will share with customers 50% of any capacity sales. The order approved recovery of IPL’s pension expenses and a return on IPL’s discretionary pension fundings. While the IURC noted in the order that they found IPL’s Service Company cost allocations to be reasonable, IPL was directed to request the FERC to review its Service Company allocations. Such review is currently underway. The IURC also closed their investigation into IPL’s underground network.

Some of the intervening parties in the IURC rate case filed petitions for reconsideration of the IURC’s March 2016 order with respect to certain issues. These petitions were subsequently denied by the IURC. In addition, certain intervening parties have filed notices of appeal of the order. On April 5, 2017, the Indiana Court of Appeals affirmed the IURC’s March 2016 order.

In May 2014, IPL received an order from the IURC granting approval to build a 644 to 685 MW CCGT at Eagle Valley. The costs to build and operate the CCGT, other than fuel costs, will not be recoverable by IPL through rates until the conclusion of a base rate case proceeding with the IURC after construction is completed.

On December 22, 2016, IPL filed a petition with the IURC for authority to increase its basic rates and charges primarily to recover the cost of the new CCGT. The CCGT was previously expected to be completed in the first half of 2017, but is now expected to be completed in the first half of 2018. To address this change, on February 24, 2017, IPL filed a motion to withdraw the case without prejudice or alternatively amend the petition and case-in-chief at a later date. On March 15, 2017, the IURC dismissed the rate case without prejudice. IPL will file a new base rate case with the IURC to coincide with the completion of the CCGT.