Benefit Plans (Schedule Of Net Periodic Benefit Costs) (Details) - USD ($) $ in Thousands		12 Months Ended
	Jan. 01, 2016	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Service cost		$ 7,412	$ 8,450	$ 7,344
Interest cost		27,343	25,220	25,305
Expected return on assets		(29,907)	(40,801)	(44,672)
Defined Benefit Plan Amortization of prior service cost net of acceleration component of curtailment charge		3,823	3,837	4,240
Recognized actuarial loss		11,084	11,403	13,195
Recognized settlement loss		0	1,230	146
Net periodic benefit cost		19,755	9,339	5,558
Less: amounts capitalized		1,237	1,223	845
Amount charged to expense		$ 18,518	8,116	4,713
Expected return on plan assets		4.50%
Indianapolis Power And Light Company
Defined Benefit Plan Disclosure [Line Items]
Service cost		$ 7,412	8,450	7,344
Interest cost		27,343	25,220	25,305
Expected return on assets		(29,907)	(40,801)	(44,672)
Defined Benefit Plan Amortization of prior service cost net of acceleration component of curtailment charge		3,823	3,837	4,240
Recognized actuarial loss		11,084	11,403	13,195
Recognized settlement loss		0	1,230	146
Net periodic benefit cost		19,755	9,339	5,558
Less: amounts capitalized		1,237	1,223	845
Amount charged to expense		$ 18,518	$ 8,116	$ 4,713
Expected return on plan assets		4.50%
Pension Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate	3.33%	4.36%	3.67%	4.29%
Expected return on plan assets		4.50%	5.45%	6.75%
Pension Benefit [Member] | Indianapolis Power And Light Company
Defined Benefit Plan Disclosure [Line Items]
Discount rate	3.33%	4.36%	3.67%	4.29%
Expected return on plan assets		4.50%	5.45%	6.75%
Supplemental Retirement Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate	3.05%	4.24%	3.60%	4.00%
Expected return on plan assets		4.50%	5.45%	6.75%
Supplemental Retirement Plan [Member] | Indianapolis Power And Light Company
Defined Benefit Plan Disclosure [Line Items]
Discount rate	3.05%	4.24%	3.60%	4.00%
Expected return on plan assets		4.50%	5.45%	6.75%