Benefit Plans (Schedule Of Fair Value Of Pension Plan Assets) (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2013
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	$ 769,704	$ 684,485	$ 738,947
Percentage by asset category	100.00%	100.00%
Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	$ 7,046	$ 684,485
Significant Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	762,658	0
Short-Term Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	$ 2,599	$ 3,597
Percentage by asset category	0.00%	1.00%
Short-Term Investments [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	$ 2,599	$ 3,597
US Government Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	$ 154,798
Percentage by asset category	20.00%
US Government Debt Securities [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	$ 39
US Government Debt Securities [Member] | Significant Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	154,759
Equity Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	$ 214,369
Percentage by asset category	28.00%
Equity Funds [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	$ 2,744
Equity Funds [Member] | Significant Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	211,625
Fixed Income [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	$ 397,938	$ 497,323
Percentage by asset category	52.00%	72.00%
Fixed Income [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	$ 1,664	$ 497,323
Fixed Income [Member] | Significant Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	396,274
US Treasury Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets		$ 129,305
Percentage by asset category		19.00%
US Treasury Securities [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets		$ 129,305
Domestic Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets		$ 1,906
Percentage by asset category		0.00%
Domestic Equity Securities [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets		$ 1,906
Foreign Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets		$ 52,354
Percentage by asset category		8.00%
Foreign Equity Securities [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets		$ 52,354
Indianapolis Power And Light Company
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	$ 769,704	$ 684,485		$ 738,947
Percentage by asset category	100.00%	100.00%
Indianapolis Power And Light Company | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	$ 7,046	$ 684,485
Indianapolis Power And Light Company | Significant Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	762,658	0
Indianapolis Power And Light Company | Short-Term Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	$ 2,599	$ 3,597
Percentage by asset category	0.00%	1.00%
Indianapolis Power And Light Company | Short-Term Investments [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	$ 2,599	$ 3,597
Indianapolis Power And Light Company | US Government Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	$ 154,798
Percentage by asset category	20.00%
Indianapolis Power And Light Company | US Government Debt Securities [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	$ 39
Indianapolis Power And Light Company | US Government Debt Securities [Member] | Significant Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	154,759
Indianapolis Power And Light Company | Equity Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	$ 214,369
Percentage by asset category	28.00%
Indianapolis Power And Light Company | Equity Funds [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	$ 2,744
Indianapolis Power And Light Company | Equity Funds [Member] | Significant Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	211,625
Indianapolis Power And Light Company | Fixed Income [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	$ 397,938	$ 497,323
Percentage by asset category	52.00%	72.00%
Indianapolis Power And Light Company | Fixed Income [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	$ 1,664	$ 497,323
Indianapolis Power And Light Company | Fixed Income [Member] | Significant Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	$ 396,274
Indianapolis Power And Light Company | US Treasury Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets		$ 129,305
Percentage by asset category		19.00%
Indianapolis Power And Light Company | US Treasury Securities [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets		$ 129,305
Indianapolis Power And Light Company | Domestic Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets		$ 1,906
Percentage by asset category		0.00%
Indianapolis Power And Light Company | Domestic Equity Securities [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets		$ 1,906
Indianapolis Power And Light Company | Foreign Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets		$ 52,354
Percentage by asset category		8.00%
Indianapolis Power And Light Company | Foreign Equity Securities [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets		$ 52,354