Schedule I - Condensed Financial Information Of Registrant (Unconsolidated Balance Sheet) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	$ 18,487	$ 27,283	$ 31,796	$ 48,022
Deferred tax asset - current	10,809	12,352
Prepayments and other current assets	21,135	16,838
Total current assets	299,337	306,735
Other investments	5,333	5,029
Total other assets	5,866	5,568
TOTAL	3,285,347	3,271,652
Paid in capital	11,811	11,367
Accumulated deficit	(15,030)	(17,213)
Total common shareholder's deficit	(3,219)	(5,846)
Long-term debt	1,651,120	1,760,316
Total capitalization	1,707,685	1,814,254
Accrued interest	31,979	31,008
Total current liabilities	358,518	264,453
Total deferred credits and other long-term liabilities	1,219,144	1,192,945
TOTAL	3,285,347	3,271,652
Ipalco Enterprises, Inc. [Member]
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	2,750	3,135	4,915	4,010
Deferred tax asset - current	27	28
Prepayments and other current assets	70	56
Total current assets	2,847	3,219
Investment in subsidiaries	791,673	786,926
Other investments	2,825	2,707
Deferred tax asset - long term	122	143
Deferred financing costs	8,172	9,728
Total other assets	802,792	799,504
TOTAL	805,639	802,723
Paid in capital	11,811	11,367
Accumulated deficit	(15,030)	(17,213)
Total common shareholder's deficit	(3,219)	(5,846)
Long-term debt	796,916	796,141
Total capitalization	793,697	790,295
Accounts payable and accrued expenses	281	237
Accrued income taxes	1,055	1,588
Accrued interest	10,583	10,583
Total current liabilities	11,919	12,408
Total deferred credits and other long-term liabilities	23	20
TOTAL	$ 805,639	$ 802,723