Utiilty Plant In Service (Schedule Of Original Cost Of Utility Plant In Service) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Production	$ 2,708,826	$ 2,684,443
Transmission	249,577	238,762
Distribution	1,249,445	1,219,070
General plant	174,686	170,740
Total utility plant in service	4,382,534	4,313,015
Indianapolis Power And Light Company [Member]
Production	2,708,826	2,684,443
Transmission	249,577	238,762
Distribution	1,249,445	1,219,070
General plant	174,686	170,740
Total utility plant in service	$ 4,382,534	$ 4,313,015