Income Taxes (Schedule Of Federal And State Income Taxed Charged To Income) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Total current income taxes	$ 67,162	$ 62,609	$ 75,939
Total federal and state income tax provisions	47,699	37,133	50,529
Charged To Utility Operating Expense [Member]
Current income taxes, Federal	55,201	54,377	61,999
Current income taxes, State	16,641	16,539	18,818
Total current income taxes	71,842	70,916	80,817
Deferred income taxes, Federal	(3,285)	(5,027)	(4,697)
Deferred income taxes, State	204	(1,608)	1,539
Total deferred income taxes	(3,081)	(6,635)	(3,158)
Net amortization of investment credit	(1,599)	(1,672)	(1,720)
Total federal and state income tax provisions	67,162	62,609	75,939
Charged To Other Income And Deductions [Member]
Current income taxes, Federal	(15,646)	(19,639)	(19,239)
Current income taxes, State	(4,127)	(5,255)	(5,291)
Total current income taxes	(19,773)	(24,894)	(24,530)
Deferred income taxes, Federal	251	(476)	(692)
Deferred income taxes, State	59	(106)	(188)
Total deferred income taxes	310	(582)	(880)
Total federal and state income tax provisions	(19,463)	(25,476)	(25,410)
Indianapolis Power And Light Company [Member]
Total current income taxes	67,162	62,609	75,939
Total federal and state income tax provisions	67,816	66,408	75,687
Indianapolis Power And Light Company [Member] | Charged To Utility Operating Expense [Member]
Current income taxes, Federal	55,201	54,377	61,999
Current income taxes, State	16,641	16,539	18,818
Total current income taxes	71,842	70,916	80,817
Deferred income taxes, Federal	(3,285)	(5,027)	(4,697)
Deferred income taxes, State	204	(1,608)	1,539
Total deferred income taxes	(3,081)	(6,635)	(3,158)
Net amortization of investment credit	(1,599)	(1,672)	(1,720)
Total federal and state income tax provisions	67,162	62,609	75,939
Indianapolis Power And Light Company [Member] | Charged To Other Income And Deductions [Member]
Current income taxes, Federal	395	2,883	(286)
Current income taxes, State	245	916	39
Total current income taxes	640	3,799	(247)
Deferred income taxes, Federal	10	(5)	(1)
Deferred income taxes, State	4	5	(4)
Total deferred income taxes	14		(5)
Total federal and state income tax provisions	$ 654	$ 3,799	$ (252)