Overview and Summary of Significant Accounting Policies (Details) $ in Thousands		1 Months Ended		12 Months Ended
	Oct. 31, 2018 USD ($)	Oct. 31, 2018 USD ($)	Mar. 31, 2016 USD ($)	Dec. 31, 2019 USD ($) customer generating_station item segment mi MW	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2013 USD ($)	Dec. 31, 2012 USD ($)
Significant Accounting Policies [Line Items]
Accounts Receivable, Gross, Current				$ 163,100
Accumulated Other Comprehensive Income (Loss), Net of Tax				(19,750)	$ 0
Other Comprehensive Income (Loss), Net of Tax					0	$ 0
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax				(19,750)	0	0
Public Utilities, Approved Rate Increase (Decrease), Amount		$ 43,900	$ 30,800
Public Utilities, Inventory				26,907	32,457
Receivables from Customers				90,747	91,426
Cash and Cash Equivalents, at Carrying Value				48,152	33,199
Capitalized Computer Software, Gross				139,600	129,700
Service cost				7,412	8,450	7,344
Interest cost				$ 27,343	25,220	25,305
Ownership interest in IPALCO by AES U.S. Investments (percent)				82.35%
Ownership interest in IPALCO by CDPQ (percent)				17.65%
Number of customers | customer				500,000
Distance of Furthest Customer from Indianapolis | mi				40
Number of generating stations | generating_station				4
Electric generation capability for winter, megawatts | MW				3,705
Electric generation capability for summer, megawatts | MW				3,560
Total other non-current assets				$ 22,082	10,971
Unbilled energy revenues				65,822	68,893
Provision for doubtful accounts				5,500	6,000	$ 5,900
Loss contingencies accrued				$ 4,500	$ 4,600
Number of suppliers | item				4
Capitalized amount, rate				6.90%	6.40%	6.60%
Depreciation rate				3.70%	4.20%	4.10%
Depreciation expense				$ 228,200	$ 235,200	$ 209,800
Utility plant assets				$ 4,100,000
Number of segments | segment				2
Capitalized Computer Software, Accumulated Amortization				$ 74,700	88,800
Capitalized Computer Software, Amortization				7,500	5,500	4,300
Capitalized software, estimated amortization expense in year two				50,000
Capitalized Software, estimated amortization expense for the next 12 months				10,000
capitalized software, estimated amortization expense for year two				10,000
Capitalized software, estimated amortization expense for year three				10,000
Capitalized software, estimated amortization expense year four				10,000
Restricted Cash and Cash Equivalents				400	400
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents				48,552	33,599	30,681	$ 34,953
Accounts Receivable, Related Parties				2,717	5,720
Other Receivables				3,857	4,341
Allowance for Doubtful Accounts Receivable				(2,053)	(2,821)
Receivables, Net, Current				161,090	167,559
Materials and Supplies, Average Cost				56,662	67,211
Inventory, Net				83,569	99,668
capitalized software, estimated amortization expense year five				$ 10,000
Harding Street [Member]
Significant Accounting Policies [Line Items]
Amount of New Operation for Battery Storage Unit, megawatts | MW				20
Labor Force Concentration Risk [Member]
Significant Accounting Policies [Line Items]
Concentration risk percentage				69.00%
Supplier Concentration Risk [Member]
Significant Accounting Policies [Line Items]
Concentration risk percentage				33.00%
Parent Company [Member]
Significant Accounting Policies [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax				$ (19,750)	0
Other Comprehensive Income (Loss), Net of Tax				(19,750)	0	0
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax				(19,750)	0	0
Cash and Cash Equivalents, at Carrying Value				3,709	4,409	16,383		$ 7,370
Total other non-current assets				1,436,748	1,434,507
Indianapolis Power And Light Company
Significant Accounting Policies [Line Items]
Public Utilities, Approved Rate Increase (Decrease), Amount		$ 43,900
Public Utilities, Inventory				26,907	32,457
Receivables from Customers				90,747	91,426
Cash and Cash Equivalents, at Carrying Value				42,189	26,834				$ 12,342	$ 26,607
Capitalized Computer Software, Gross				139,600	129,700
Service cost				7,412	8,450	7,344
Interest cost				$ 27,343	25,220	25,305
Number of customers | customer				500,000
Distance of Furthest Customer from Indianapolis | mi				40
Electric generation capability for winter, megawatts | MW				3,705
Electric generation capability for summer, megawatts | MW				3,560
Total other non-current assets				$ 18,045	6,959
Unbilled energy revenues				65,822	68,893
Provision for doubtful accounts				5,500	6,000	$ 5,900
Loss contingencies accrued				$ 4,500	$ 4,600
Number of suppliers | item				4
Capitalized amount, rate				6.90%	6.40%	6.60%
Depreciation rate				3.70%	4.20%	4.10%
Depreciation expense				$ 228,200	$ 235,200	$ 209,800
Utility plant assets				4,100,000
Capitalized Computer Software, Accumulated Amortization				74,700	88,800
Capitalized Computer Software, Amortization				7,500	5,500	$ 4,300
Capitalized software, estimated amortization expense in year two				50,000
Capitalized Software, estimated amortization expense for the next 12 months				10,000
capitalized software, estimated amortization expense for year two				10,000
Capitalized software, estimated amortization expense for year three				10,000
Capitalized software, estimated amortization expense year four				10,000
Restricted Cash and Cash Equivalents				400	400
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents				42,589	27,234				$ 12,342
Accounts Receivable, Related Parties				2,992	6,030
Other Receivables				3,857	4,341
Allowance for Doubtful Accounts Receivable				(2,053)	(2,821)
Receivables, Net, Current				161,365	167,869
Materials and Supplies, Average Cost				56,662	67,212
Inventory, Net				83,569	99,669
capitalized software, estimated amortization expense year five				$ 10,000
Indianapolis Power And Light Company | Harding Street [Member]
Significant Accounting Policies [Line Items]
Amount of New Operation for Battery Storage Unit, megawatts | MW				20
Indianapolis Power And Light Company | Labor Force Concentration Risk [Member]
Significant Accounting Policies [Line Items]
Concentration risk percentage				69.00%
Indianapolis Power And Light Company | Supplier Concentration Risk [Member]
Significant Accounting Policies [Line Items]
Concentration risk percentage				33.00%
AES U.S. Holdings, LLC [Member]
Significant Accounting Policies [Line Items]
Ownership Interest in Parent Company, Percent				85.00%
CDPQ [Member]
Significant Accounting Policies [Line Items]
Ownership Interest in Parent Company, Percent				15.00%
Physical Unit [Member]
Significant Accounting Policies [Line Items]
Collective bargaining agreement expiration date				Dec. 06, 2021
Physical Unit [Member] | Indianapolis Power And Light Company
Significant Accounting Policies [Line Items]
Collective bargaining agreement expiration date				Dec. 06, 2021
Clerical-Technical Unit [Member]
Significant Accounting Policies [Line Items]
Collective bargaining agreement expiration date				Feb. 13, 2023
Clerical-Technical Unit [Member] | Indianapolis Power And Light Company
Significant Accounting Policies [Line Items]
Collective bargaining agreement expiration date				Feb. 13, 2023
Increase to Annual Depreciation Rate [Member]
Significant Accounting Policies [Line Items]
Public Utilities, Approved Rate Increase (Decrease), Amount	$ 28,700
Increase to Annual Depreciation Rate [Member] | Indianapolis Power And Light Company
Significant Accounting Policies [Line Items]
Public Utilities, Approved Rate Increase (Decrease), Amount	$ 28,700
Interest Rate Contract [Member]
Significant Accounting Policies [Line Items]
Accumulated Other Comprehensive Income (Loss), Cumulative Changes in Net Gain (Loss) from Cash Flow Hedges, Effect Net of Tax				$ (19,750)
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax				(19,750)
Interest Rate Contract [Member] | Parent Company [Member]
Significant Accounting Policies [Line Items]
Accumulated Other Comprehensive Income (Loss), Cumulative Changes in Net Gain (Loss) from Cash Flow Hedges, Effect Net of Tax				$ (19,750)	$ 0