Benefit Plans (Information For Pension Plans With A Benefit Obligation In Excess Of Plan Assets) (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Entity Information [Line Items]
Defined Benefit Plan, Pension Plan with Projected Benefit Obligation in Excess of Plan Assets, Projected Benefit Obligation	$ 782,795	$ 697,228
Defined Benefit Plan, Pension Plan with Projected Benefit Obligation in Excess of Plan Assets, Plan Assets	769,704	684,485
Benefit obligation in excess of plan assets	13,091	12,743
Indianapolis Power And Light Company
Entity Information [Line Items]
Defined Benefit Plan, Pension Plan with Projected Benefit Obligation in Excess of Plan Assets, Projected Benefit Obligation	782,795	697,228
Defined Benefit Plan, Pension Plan with Projected Benefit Obligation in Excess of Plan Assets, Plan Assets	769,704	684,485
Benefit obligation in excess of plan assets	$ 13,091	$ 12,743