Utility Plant In Service (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Public Utility, Property, Plant and Equipment [Line Items]
Revisions in estimated cash flows	$ 0.0	$ 21.6
Direct first mortgage lien	1,608.8
Non-contractually required removal costs of utility plant in service	737.1	705.6
Contractually required removal costs of utility plant in service	79.5	80.6
Indianapolis Power And Light Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Revisions in estimated cash flows	0.0	21.6
Direct first mortgage lien	1,608.8
Non-contractually required removal costs of utility plant in service	737.1	705.6
Contractually required removal costs of utility plant in service	$ 79.5	$ 80.6