Regulatory Assets And Liabilities (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Regulatory Assets And Liabilities [Line Items]
Regulatory liabilities, current	$ 52,654	$ 51,024
Regulatory assets, current	37,398	28,399
Regulatory assets	$ 355,614	$ 395,077
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	21.00%	21.00%	35.00%
Regulatory liabilities	$ 846,430	$ 870,255
Indianapolis Power And Light Company
Regulatory Assets And Liabilities [Line Items]
Regulatory liabilities, current	52,654	51,024
Regulatory assets, current	37,398	28,399
Regulatory assets	$ 355,614	$ 395,077
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	21.00%	21.00%	35.00%
Effective Income Tax Rate Reconciliation Tax Cuts and Jobs Act of 2017 Percent		21.00%
Regulatory liabilities	$ 846,430	$ 870,255
Minimum [Member]
Regulatory Assets And Liabilities [Line Items]
Regulatory Assets Amortization Period	1 year
Minimum [Member] | Indianapolis Power And Light Company
Regulatory Assets And Liabilities [Line Items]
Regulatory Assets Amortization Period	1 year
Maximum [Member]
Regulatory Assets And Liabilities [Line Items]
Regulatory Assets Amortization Period	45 years
Maximum [Member] | Indianapolis Power And Light Company
Regulatory Assets And Liabilities [Line Items]
Regulatory Assets Amortization Period	45 years
Deferred Income Tax Charge [Member]
Regulatory Assets And Liabilities [Line Items]
Regulatory liabilities	$ 122,156	141,100
Deferred Income Tax Charge [Member] | Indianapolis Power And Light Company
Regulatory Assets And Liabilities [Line Items]
Regulatory liabilities	$ 122,156	141,100
Deferred Project Costs [Member]
Regulatory Assets And Liabilities [Line Items]
Regulatory assets		88,052
Deferred Project Costs [Member] | Indianapolis Power And Light Company
Regulatory Assets And Liabilities [Line Items]
Regulatory assets		$ 88,052