Income Taxes (Reconciliation Of Unrecognized Tax Benefits) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Unrecognized tax benefits at January 1	$ 5,354	$ 4,757	$ 7,947
Gross increases - current period tax positions	997	753	753
Gross decreases - prior period tax positions	(213)	(156)	(3,943)
Unrecognized tax benefits at December 31	6,138	5,354	4,757
Indianapolis Power And Light Company [Member]
Unrecognized tax benefits at January 1	5,354	4,757	7,947
Gross increases - current period tax positions	997	753	753
Gross decreases - prior period tax positions	(213)	(156)	(3,943)
Unrecognized tax benefits at December 31	$ 6,138	$ 5,354	$ 4,757