Benefit Plans (Information For Pension Plans With An Accumulated Benefit Obligation In Excess Of Plan Assets) (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Entity Information [Line Items]
Accumulated benefit obligation	$ 771,592	$ 687,136
Plan assets	769,704	684,485
Accumulated benefit obligation in excess of plan assets	1,888	2,651
Indianapolis Power And Light Company
Entity Information [Line Items]
Accumulated benefit obligation	771,592	687,136
Plan assets	769,704	684,485
Accumulated benefit obligation in excess of plan assets	$ 1,888	$ 2,651