Utility Plant In Service (Schedule Of Original Cost Of Utility Plant In Service) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Entity Information [Line Items]
Production	$ 3,249,563	$ 2,923,349
Transmission	380,881	376,659
Distribution	1,487,380	1,433,044
General plant	267,229	264,794
Total utility plant in service	5,385,053	4,997,846
Indianapolis Power And Light Company [Member]
Entity Information [Line Items]
Production	3,249,563	2,923,349
Transmission	380,881	376,659
Distribution	1,487,380	1,433,044
General plant	267,229	264,794
Total utility plant in service	$ 5,385,053	$ 4,997,846