Pension And Other Postretirement Benefits (Schedule Of Asset Allocation Guidelines) (Details)	12 Months Ended
	Dec. 31, 2012
Liability Managed Fixed Income [Member]
Defined Benefit Plan Disclosure [Line Items]
Lower Limit	10.00%	[1]
Target Allocation	16.00%	[1]
Upper Limit	40.00%	[1]
Return	5.30%	[1],[2]
Risk	3.60%	[1],[3]
Liability Managed Fixed Income [Member] | Indianapolis Power And Light Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Lower Limit	10.00%	[1]
Target Allocation	16.00%	[1]
Upper Limit	40.00%	[1]
Return	5.30%	[1],[2]
Risk	3.60%	[1],[3]
Core Fixed Income [Member]
Defined Benefit Plan Disclosure [Line Items]
Lower Limit	10.00%	[1]
Target Allocation	16.00%	[1]
Upper Limit	22.00%	[1]
Return	5.40%	[1],[2]
Risk	3.80%	[1],[3]
Core Fixed Income [Member] | Indianapolis Power And Light Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Lower Limit	10.00%	[1]
Target Allocation	16.00%	[1]
Upper Limit	22.00%	[1]
Return	5.40%	[1],[2]
Risk	3.80%	[1],[3]
High Yield Fixed Income [Member]
Defined Benefit Plan Disclosure [Line Items]
Lower Limit	3.00%
Target Allocation	8.00%
Upper Limit	13.00%
Return	8.90%	[2]
Risk	9.50%	[3]
High Yield Fixed Income [Member] | Indianapolis Power And Light Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Lower Limit	3.00%
Target Allocation	8.00%
Upper Limit	13.00%
Return	8.90%	[2]
Risk	9.50%	[3]
U.S. Large Cap Equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Lower Limit	20.00%
Target Allocation	30.00%
Upper Limit	40.00%
Return	10.40%	[2]
Risk	15.40%	[3]
U.S. Large Cap Equity [Member] | Indianapolis Power And Light Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Lower Limit	20.00%
Target Allocation	30.00%
Upper Limit	40.00%
Return	10.40%	[2]
Risk	15.40%	[3]
U.S. Mid Cap Equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Lower Limit	2.50%
Target Allocation	5.00%
Upper Limit	7.50%
Return	11.20%	[2]
Risk	17.10%	[3]
U.S. Mid Cap Equity [Member] | Indianapolis Power And Light Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Lower Limit	2.50%
Target Allocation	5.00%
Upper Limit	7.50%
Return	11.20%	[2]
Risk	17.10%	[3]
U.S. Small Cap Equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Lower Limit	2.50%
Target Allocation	5.00%
Upper Limit	7.50%
Return	12.00%	[2]
Risk	19.90%	[3]
U.S. Small Cap Equity [Member] | Indianapolis Power And Light Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Lower Limit	2.50%
Target Allocation	5.00%
Upper Limit	7.50%
Return	12.00%	[2]
Risk	19.90%	[3]
International Equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Lower Limit	5.00%
Target Allocation	10.00%
Upper Limit	15.00%
Return	10.30%	[2]
Risk	17.70%	[3]
International Equity [Member] | Indianapolis Power And Light Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Lower Limit	5.00%
Target Allocation	10.00%
Upper Limit	15.00%
Return	10.30%	[2]
Risk	17.70%	[3]
REIT [Member]
Defined Benefit Plan Disclosure [Line Items]
Lower Limit	0.00%
Target Allocation	5.00%
Upper Limit	10.00%
Return	10.40%	[2]
Risk	18.80%	[3]
REIT [Member] | Indianapolis Power And Light Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Lower Limit	0.00%
Target Allocation	5.00%
Upper Limit	10.00%
Return	10.40%	[2]
Risk	18.80%	[3]
Hedge Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Lower Limit	0.00%	[4]
Target Allocation	5.00%	[4]
Upper Limit	10.00%	[4]
Return	9.30%	[2],[4]
Risk	8.40%	[3],[4]
Hedge Funds [Member] | Indianapolis Power And Light Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Lower Limit	0.00%	[4]
Target Allocation	5.00%	[4]
Upper Limit	10.00%	[4]
Return	9.30%	[2],[4]
Risk	8.40%	[3],[4]

[1] Upper limit for all assets held in the Liability Hedging Portfolio is 40%

[2] Expected long-term annual return

[3] Expected standard deviation

[4] Alternative investments (combined) not to exceed 10%