Income Taxes (Schedule Of Deferred Tax Assets And Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Entity Information [Line Items]
Relating to utility property, net	$ 475,911	$ 569,204
Regulatory assets recoverable through future rates	66,661	180,608
Other	6,654	11,612
Total deferred tax liabilities	549,226	761,424
Investment tax credit	240	927
Regulatory liabilities including ARO	278,529	272,001
Employee benefit plans	18,564	27,358
Other	6,636	11,408
Total deferred tax assets	303,969	311,694
Deferred income taxes – net	245,257	449,730
Indianapolis Power And Light Company [Member]
Entity Information [Line Items]
Relating to utility property, net	475,911	569,204
Regulatory assets recoverable through future rates	66,661	180,608
Other	6,256	11,090
Total deferred tax liabilities	548,828	760,902
Investment tax credit	240	927
Regulatory liabilities including ARO	278,529	272,001
Employee benefit plans	18,564	27,358
Other	6,683	11,396
Total deferred tax assets	304,016	311,682
Deferred income taxes – net	$ 244,812	$ 449,220