Fair Value (Summary Of Fair Value Assets And Liabilities Measured On A Recurring Basis, Level 3) (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Entity Information [Line Items]
Investments, Fair Value Disclosure	$ 2,879	$ 2,586
Financial transmission rights	864	3,099
Total financial assets measured at fair value	3,743	5,685
Other derivative liabilities	26,560	53
Total financial liabilities measured at fair value	26,560	53
Indianapolis Power And Light Company
Entity Information [Line Items]
Investments, Fair Value Disclosure	2,879	2,586
Financial transmission rights	864	3,099
Total financial assets measured at fair value	3,743	5,685
Other derivative liabilities		53
Total financial liabilities measured at fair value		53
Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Entity Information [Line Items]
Investments, Fair Value Disclosure	25	21
Financial transmission rights	0	0
Total financial assets measured at fair value	25	21
Other derivative liabilities	0	0
Total financial liabilities measured at fair value	0	0
Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Indianapolis Power And Light Company
Entity Information [Line Items]
Investments, Fair Value Disclosure	25	21
Financial transmission rights	0	0
Total financial assets measured at fair value	25	21
Other derivative liabilities		0
Total financial liabilities measured at fair value		0
Significant Observable Inputs (Level 2) [Member]
Entity Information [Line Items]
Investments, Fair Value Disclosure	2,854	2,565
Financial transmission rights	0	0
Total financial assets measured at fair value	2,854	2,565
Other derivative liabilities	26,560	0
Total financial liabilities measured at fair value	26,560	0
Significant Observable Inputs (Level 2) [Member] | Indianapolis Power And Light Company
Entity Information [Line Items]
Investments, Fair Value Disclosure	2,854	2,565
Financial transmission rights	0	0
Total financial assets measured at fair value	2,854	2,565
Other derivative liabilities		0
Total financial liabilities measured at fair value		0
Unobservable Inputs (Level 3) [Member]
Entity Information [Line Items]
Investments, Fair Value Disclosure	0	0
Financial transmission rights	864	3,099
Total financial assets measured at fair value	864	3,099
Other derivative liabilities	0	53
Total financial liabilities measured at fair value	0	53
Unobservable Inputs (Level 3) [Member] | Indianapolis Power And Light Company
Entity Information [Line Items]
Investments, Fair Value Disclosure	0	0
Financial transmission rights	864	3,099
Total financial assets measured at fair value	864	3,099
Other derivative liabilities		53
Total financial liabilities measured at fair value		53
Money Market Funds [Member]
Entity Information [Line Items]
Investments, Fair Value Disclosure	25	21
Money Market Funds [Member] | Indianapolis Power And Light Company
Entity Information [Line Items]
Investments, Fair Value Disclosure	25	21
Money Market Funds [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Entity Information [Line Items]
Investments, Fair Value Disclosure	25	21
Money Market Funds [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Indianapolis Power And Light Company
Entity Information [Line Items]
Investments, Fair Value Disclosure	25	21
Money Market Funds [Member] | Significant Observable Inputs (Level 2) [Member]
Entity Information [Line Items]
Investments, Fair Value Disclosure	0	0
Money Market Funds [Member] | Significant Observable Inputs (Level 2) [Member] | Indianapolis Power And Light Company
Entity Information [Line Items]
Investments, Fair Value Disclosure	0	0
Money Market Funds [Member] | Unobservable Inputs (Level 3) [Member]
Entity Information [Line Items]
Investments, Fair Value Disclosure	0	0
Money Market Funds [Member] | Unobservable Inputs (Level 3) [Member] | Indianapolis Power And Light Company
Entity Information [Line Items]
Investments, Fair Value Disclosure	0	0
Mutual Fund [Member]
Entity Information [Line Items]
Investments, Fair Value Disclosure	2,854	2,565
Mutual Fund [Member] | Indianapolis Power And Light Company
Entity Information [Line Items]
Investments, Fair Value Disclosure	2,854	2,565
Mutual Fund [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Entity Information [Line Items]
Investments, Fair Value Disclosure	0	0
Mutual Fund [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Indianapolis Power And Light Company
Entity Information [Line Items]
Investments, Fair Value Disclosure	0	0
Mutual Fund [Member] | Significant Observable Inputs (Level 2) [Member]
Entity Information [Line Items]
Investments, Fair Value Disclosure	2,854	2,565
Mutual Fund [Member] | Significant Observable Inputs (Level 2) [Member] | Indianapolis Power And Light Company
Entity Information [Line Items]
Investments, Fair Value Disclosure	2,854	2,565
Mutual Fund [Member] | Unobservable Inputs (Level 3) [Member]
Entity Information [Line Items]
Investments, Fair Value Disclosure	0	0
Mutual Fund [Member] | Unobservable Inputs (Level 3) [Member] | Indianapolis Power And Light Company
Entity Information [Line Items]
Investments, Fair Value Disclosure	$ 0	$ 0