Condensed Consolidated Statements Of Cash Flows (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
CASH FLOWS FROM OPERATIONS:
Net income	$ 71,996	$ 60,575	$ 79,947
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	179,217	169,421	163,337
Amortization of regulatory assets	2,206	2,529	6,777
Deferred income taxes and investment tax credit adjustments - net	(4,370)	(8,889)	(5,759)
Loss on early extinguishment of debt		15,422
Termination of interest rate swap		(12,572)
Allowance for equity funds used during construction	(881)	(3,772)	(3,795)
Gain on sale of nonutility property		(13,320)
Change in certain assets and liabilities:
Accounts receivable	(5,501)	4,531	(13,389)
Fuel, materials and supplies	4,339	(17,938)	(764)
Income taxes receivable or payable	(6,681)	8,272	(5,443)
Financial transmission rights	360	(621)	(1,214)
Accounts payable and accrued expenses	(2,947)	2,514	19,698
Accrued real estate and personal property taxes	1,945	648	(6,819)
Accrued interest	971	1,777	354
Pension and other postretirement benefit expenses	15,846	58,883	13,473
Short-term and long-term regulatory assets and liabilities	(43,514)	(91,761)	(32,484)
Other - net	1,780	7,385	6,612
Net cash provided by operating activities	214,766	183,084	220,531
CASH FLOWS FROM INVESTING ACTIVITIES:
Capital expenditures - utility	(129,747)	(209,851)	(163,652)
Proceeds from sales and maturities of short-term investments		2,000
Proceeds from sales of assets	1	13,467
Grants under the American Recovery and Reinvestment Act of 2009	6,028	7,919	5,130
Cost of removal, net of salvage	(9,251)	(14,896)	(3,035)
Other	(6,608)	(3,958)	(6,655)
Net cash used in investing activities	(139,577)	(205,319)	(168,212)
CASH FLOWS FROM FINANCING ACTIVITIES:
Short-term debt borrowings	73,000	138,000	9,508
Short-term debt repayments	(87,000)	(124,000)	(40,000)
Long-term borrowings, net of discount		634,581	40,000
Retirement of long-term debt and early tender premium		(559,145)
Dividends on common stock	(66,600)	(59,231)	(73,200)
Preferred dividends of subsidiary	(3,213)	(3,213)	(3,213)
Deferred financing costs paid	(166)	(8,633)	(1,306)
Other	(6)	(637)	(334)
Net cash used in financing activities	(83,985)	17,722	(68,545)
Net change in cash and cash equivalents	(8,796)	(4,513)	(16,226)
Cash and cash equivalents at beginning of period	27,283	31,796	48,022
Cash and cash equivalents at end of period	18,487	27,283	31,796
Supplemental disclosures of cash flow information:
Interest (net of amount capitalized)	103,254	108,488	113,458
Income taxes	58,750	37,750	61,650
Indianapolis Power And Light Company [Member]
CASH FLOWS FROM OPERATIONS:
Net income	104,129	105,398	119,788
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	176,800	167,216	161,300
Amortization of regulatory assets	2,206	2,529	6,777
Deferred income taxes and investment tax credit adjustments - net	(4,666)	(8,306)	(4,884)
Termination of interest rate swap		(12,572)
Allowance for equity funds used during construction	(881)	(3,772)	(3,795)
Gain on sale of nonutility property		(13,320)
Change in certain assets and liabilities:
Accounts receivable	(5,501)	4,531	(13,461)
Fuel, materials and supplies	4,339	(17,938)	(764)
Income taxes receivable or payable	(5,825)	8,364	(6,410)
Financial transmission rights	360	(621)	(1,214)
Accounts payable and accrued expenses	(2,401)	3,153	19,785
Accrued real estate and personal property taxes	1,945	648	(6,819)
Accrued interest	971	2,577	354
Pension and other postretirement benefit expenses	15,846	58,883	13,473
Short-term and long-term regulatory assets and liabilities	(43,514)	(91,761)	(32,475)
Other - net	1,472	5,091	5,703
Net cash provided by operating activities	245,280	210,100	257,358
CASH FLOWS FROM INVESTING ACTIVITIES:
Capital expenditures - utility	(129,747)	(209,851)	(163,652)
Proceeds from sales and maturities of short-term investments		2,000
Proceeds from sales of assets	1	13,467
Grants under the American Recovery and Reinvestment Act of 2009	6,028	7,919	5,130
Cost of removal, net of salvage	(9,251)	(14,896)	(3,035)
Other	(6,790)	(3,969)	(7,396)
Net cash used in investing activities	(139,759)	(205,330)	(168,953)
CASH FLOWS FROM FINANCING ACTIVITIES:
Short-term debt borrowings	73,000	138,000	9,508
Short-term debt repayments	(87,000)	(124,000)	(40,000)
Long-term borrowings, net of discount		234,873	40,000
Retirement of long-term debt and early tender premium		(169,724)
Dividends on common stock	(96,700)	(80,603)	(111,522)
Preferred dividends of subsidiary	(3,213)	(3,213)	(3,213)
Other	(172)	(2,750)	(1,640)
Net cash used in financing activities	(114,085)	(7,417)	(106,867)
Net change in cash and cash equivalents	(8,564)	(2,647)	(18,462)
Cash and cash equivalents at beginning of period	20,606	23,253	41,715
Cash and cash equivalents at end of period	12,042	20,606	23,253
Supplemental disclosures of cash flow information:
Interest (net of amount capitalized)	54,254	53,686	52,114
Income taxes	$ 78,402	$ 66,350	$ 86,900