Income Taxes (Schedule Of Federal And State Income Taxed Charged To Income) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Taxes [Line Items]
Total current income taxes	$ 65,621	$ 73,161	$ 57,284
Income Tax Expense (Benefit), Total	48,951	61,209	31,566
Charged To Utility Operating Expense [Member]
Income Taxes [Line Items]
Current income taxes, Federal	56,512	50,482	18,661
Current income taxes, State	12,586	12,080	5,758
Total current income taxes	69,098	62,562	24,419
Deferred income taxes, Federal	(1,668)	11,885	29,165
Deferred income taxes, State	(354)	215	5,019
Total deferred income taxes	(2,022)	12,100	34,184
Net amortization of investment credit	(1,455)	(1,501)	(1,319)
Income Tax Expense (Benefit), Total	65,621	73,161	57,284
Charged To Other Income And Deductions [Member]
Income Taxes [Line Items]
Current income taxes, Federal	(13,970)	(30,558)	(18,661)
Current income taxes, State	(2,670)	(4,807)	(5,758)
Total current income taxes	(16,640)	(35,365)	(24,419)
Deferred income taxes, Federal	(52)	20,998	(2,573)
Deferred income taxes, State	22	2,415	1,274
Total deferred income taxes	(30)	23,413	(1,299)
Income Tax Expense (Benefit), Total	(16,670)	(11,952)	(25,718)
Indianapolis Power And Light Company [Member]
Income Taxes [Line Items]
Total current income taxes	65,621	73,161	57,284
Income Tax Expense (Benefit), Total	65,591	72,701	56,219
Indianapolis Power And Light Company [Member] | Charged To Utility Operating Expense [Member]
Income Taxes [Line Items]
Current income taxes, Federal	56,512	50,482	18,661
Current income taxes, State	12,586	12,080	5,758
Total current income taxes	69,098	62,562	24,419
Deferred income taxes, Federal	(1,668)	11,885	29,165
Deferred income taxes, State	(354)	215	5,019
Total deferred income taxes	(2,022)	12,100	34,184
Net amortization of investment credit	(1,455)	(1,501)	(1,319)
Income Tax Expense (Benefit), Total	65,621	73,161	57,284
Indianapolis Power And Light Company [Member] | Charged To Other Income And Deductions [Member]
Income Taxes [Line Items]
Current income taxes, Federal	(135)	(1,009)	(1,715)
Current income taxes, State	70	(16)	(240)
Total current income taxes	(65)	(1,025)	(1,955)
Deferred income taxes, Federal	34	552	740
Deferred income taxes, State	1	13	150
Total deferred income taxes	35	565	890
Income Tax Expense (Benefit), Total	$ (30)	$ (460)	$ (1,065)