Schedule II - Valuation And Qualifying Accounts And Reserves (Details) (Allowance for Doubtful Accounts [Member], USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at beginning of period	$ 2,081	$ 2,218	$ 2,143
Charged to Income	3,397	3,669	3,995
Net Write-offs	3,431	3,806	3,920
Balance at End of Period	2,047	2,081	2,218
Indianapolis Power And Light Company [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at beginning of period	2,081	2,218	2,143
Charged to Income	3,397	3,669	3,995
Net Write-offs	3,431	3,806	3,920
Balance at End of Period	$ 2,047	$ 2,081	$ 2,218