Regulatory Matters (Narrative) (Details) $ in Thousands		1 Months Ended	3 Months Ended	12 Months Ended
	Oct. 31, 2018 USD ($)	Mar. 31, 2016 USD ($)	Mar. 31, 2020 MW	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($) MW	Dec. 31, 2018 USD ($)	May 31, 2021	Jul. 24, 2019 USD ($)
Regulatory Assets And Liabilities [Line Items]
Regulatory liabilities, current				$ 4,241	$ 30,036
Regulatory assets, current				63,813	45,430
Regulatory assets, non-current				$ 656,977	$ 392,801
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent				21.00%	21.00%	21.00%
Equipment recovery approved amount						$ 23,400
Revenue requirement to be included in rate						1,000
Public Utlities, Approved Shareholder Incentives				$ 7,200		$ 6,000	$ 7,500
Regulatory Assets				720,790	$ 438,231
Regulatory assets				$ 63,813	45,430
Public Utilities, Approved Rate Increase (Decrease), Amount	$ 43,900
Public Utilities, Approved Rate Increase (Decrease), Percentage	3.20%
Wholesale Sales Margins, Percent Shared with Customers		50.00%
Benchmark for Wholesale Sales Margin		$ 6,300
TDSIC Eligible Cost Recovery Through Periodic Rate Adjustment Mechanism Plan, Percent						80.00%
TDSIC Planned Recoverable Costs Deferred For Future Recovery, Percent						20.00%
Periodic Rate Adjustment Mechanism Cap, Percent						2.00%
TDSIC Plan Improvement Costs									$ 1,200,000
Preferred Resource Portfolio Coal-Fired Generation Retirement MW by 2023				630
Inventory Write-down				$ 800	0
Regulatory Liability Attributable to the Cumulative Deficiencies Calculation				500
Reduction to Revenue				5,500	10,000
Regulatory Liability, Noncurrent				826,709	839,360
Tax rate before change due to Tax Cuts and Jobs Act of 2017							35.00%
Tax rate after Tax Cuts and Jobs Act of 2017						21.00%
COVID-19 related uncollectible and incremental bad debt expense				5,400	6,400
Regulatory Liabilities				830,950	869,396
Regulatory liabilities				826,709	839,360
Customer Benefits that Flowed through the ECCRA as a Result of the 2018 Base Rate Order				50,000
Jurisdictional Revenue Requirement Approved by the IURC to be included in AES Indiana’s rates for the twelve-month period ending October 2022				$ 12,800
Retired MW Petersburg Unit 1								230
Hardy Hills Solar Project MW				195
Total Assets Recorded in the Accompanying Consolidated Balance Sheets Associated with the Hardy Hills Solar Project Acquisition				$ 51,600
Asset Acquisition, Consideration Transferred, Contingent Consideration				3,200
Estimated Projected Costs to Successfully Implement the Services Proposed in the EV Portfolio				$ 5,100
Time Period of Estimated Projected Costs to Successfully Implement the Services Proposed in the EV Portfolio				3
AES Indiana’s equipment approved for TDSIC recovery				$ 159,500
Overcollection and other credits passed to customers through rate riders [Member]
Regulatory Assets And Liabilities [Line Items]
Regulatory liabilities, current				3,006	29,493
Financial Transmission Rights [Member]
Regulatory Assets And Liabilities [Line Items]
Regulatory liabilities, current				1,235	543
Asset Retirement Obligation Costs [Member]
Regulatory Assets And Liabilities [Line Items]
Regulatory Liability, Noncurrent				722,774	723,897
Regulatory liabilities				722,774	723,897
Other Regulatory Assets (Liabilities) [Member]
Regulatory Assets And Liabilities [Line Items]
Regulatory Liability, Noncurrent				3,764	2,506
Regulatory liabilities				3,764	2,506
Current
Regulatory Assets And Liabilities [Line Items]
Approved Rate Order Benefits to Customers				0	4,700
Regulatory Liability Attributable to the Cumulative Deficiencies Calculation				7,700
Subsidiaries [Member]
Regulatory Assets And Liabilities [Line Items]
Regulatory liabilities, current				4,241	30,036
Regulatory assets, current				63,813	45,430
Regulatory assets, non-current				$ 656,977	$ 392,801
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent				21.00%	21.00%	21.00%
Equipment recovery approved amount						$ 23,400
Revenue requirement to be included in rate						1,000
Public Utlities, Approved Shareholder Incentives				$ 7,200		$ 6,000	$ 7,500
Regulatory Assets				720,790	$ 438,231
Regulatory assets				$ 63,813	45,430
Public Utilities, Approved Rate Increase (Decrease), Amount	$ 43,900
Public Utilities, Approved Rate Increase (Decrease), Percentage	3.20%
Wholesale Sales Margins, Percent Shared with Customers		50.00%
Benchmark for Wholesale Sales Margin		$ 6,300
TDSIC Eligible Cost Recovery Through Periodic Rate Adjustment Mechanism Plan, Percent						80.00%
TDSIC Planned Recoverable Costs Deferred For Future Recovery, Percent						20.00%
Periodic Rate Adjustment Mechanism Cap, Percent						2.00%
TDSIC Plan Improvement Costs									$ 1,200,000
Preferred Resource Portfolio Coal-Fired Generation Retirement MW by 2023				630		630
Inventory Write-down				$ 800	0	$ 6,200
Reduction to Revenue				5,500	10,000
Regulatory Liability, Noncurrent				826,709	839,360
Tax rate before change due to Tax Cuts and Jobs Act of 2017							35.00%
Tax rate after Tax Cuts and Jobs Act of 2017						21.00%
COVID-19 related uncollectible and incremental bad debt expense				5,400	6,400
Regulatory Liabilities				830,950	869,396
Regulatory liabilities				826,709	839,360
Customer Benefits that Flowed through the ECCRA as a Result of the 2018 Base Rate Order				50,000
Jurisdictional Revenue Requirement Approved by the IURC to be included in AES Indiana’s rates for the twelve-month period ending October 2022				$ 12,800
Hardy Hills Solar Project MW				195
Total Assets Recorded in the Accompanying Consolidated Balance Sheets Associated with the Hardy Hills Solar Project Acquisition				$ 51,600
Asset Acquisition, Consideration Transferred, Contingent Consideration				3,200
AES Indiana’s equipment approved for TDSIC recovery				159,500
Subsidiaries [Member] | Overcollection and other credits passed to customers through rate riders [Member]
Regulatory Assets And Liabilities [Line Items]
Regulatory liabilities, current				3,006	29,493
Subsidiaries [Member] | Financial Transmission Rights [Member]
Regulatory Assets And Liabilities [Line Items]
Regulatory liabilities, current				1,235	543
Subsidiaries [Member] | Asset Retirement Obligation Costs [Member]
Regulatory Assets And Liabilities [Line Items]
Regulatory Liability, Noncurrent				722,774	723,897
Regulatory liabilities				722,774	723,897
Subsidiaries [Member] | Deferred Income Tax Charge [Member]
Regulatory Assets And Liabilities [Line Items]
Regulatory Liability, Noncurrent				100,200	112,957
Regulatory liabilities				100,200	112,957
Subsidiaries [Member] | Other Regulatory Assets (Liabilities) [Member]
Regulatory Assets And Liabilities [Line Items]
Regulatory Liability, Noncurrent				3,764	2,506
Regulatory liabilities				3,764	2,506
Subsidiaries [Member] | Current
Regulatory Assets And Liabilities [Line Items]
Approved Rate Order Benefits to Customers				0	4,700
Regulatory Liability Attributable to the Cumulative Deficiencies Calculation				$ 500	7,700
Indiana [Member] | Subsidiaries [Member]
Regulatory Assets And Liabilities [Line Items]
Amount of electricity required to be purchased under purchase power agreement | MW						100
Minnesota [Member] | Subsidiaries [Member]
Regulatory Assets And Liabilities [Line Items]
Amount of electricity required to be purchased under purchase power agreement | MW						200
Solar Generated Electricity [Member] | Subsidiaries [Member]
Regulatory Assets And Liabilities [Line Items]
Amount of electricity required to be purchased under purchase power agreement | MW						94.0
Solar Generated Electricity [Member] | Subsequent Event [Member] | Subsidiaries [Member]
Regulatory Assets And Liabilities [Line Items]
Amount of electricity required to be purchased under purchase power agreement | MW			94.5
Minimum [Member]
Regulatory Assets And Liabilities [Line Items]
Regulatory Assets Amortization Period				1 year
Environmental Costs Amortization Period				3 years
TDSIC Costs Amortization Period				1 year
Minimum [Member] | Subsidiaries [Member]
Regulatory Assets And Liabilities [Line Items]
Regulatory Assets Amortization Period						1 year
Environmental Costs Amortization Period				3 years
TDSIC Costs Amortization Period				1 year
Maximum [Member]
Regulatory Assets And Liabilities [Line Items]
Regulatory Assets Amortization Period				44 years
Environmental Costs Amortization Period				44 years
TDSIC Costs Amortization Period				31 years
Maximum [Member] | Subsidiaries [Member]
Regulatory Assets And Liabilities [Line Items]
Regulatory Assets Amortization Period						44 years
Environmental Costs Amortization Period				44 years
TDSIC Costs Amortization Period				31 years
Deferred Income Tax Charge [Member]
Regulatory Assets And Liabilities [Line Items]
Regulatory Liability, Noncurrent				$ 100,171	112,957
Regulatory liabilities				100,171	112,957
Deferred Income Tax Charge [Member] | Subsidiaries [Member]
Regulatory Assets And Liabilities [Line Items]
Regulatory Liability, Noncurrent				100,171
Regulatory liabilities				100,171
Undercollections of rate riders [Member]
Regulatory Assets And Liabilities [Line Items]
Regulatory assets, current				49,998	31,569
Regulatory assets				49,998	31,569
Undercollections of rate riders [Member] | Subsidiaries [Member]
Regulatory Assets And Liabilities [Line Items]
Regulatory assets, current				49,998	31,569
Regulatory assets				49,998	31,569
Amounts being recovered through base rates [Member]
Regulatory Assets And Liabilities [Line Items]
Regulatory assets, current				13,815	13,861
Regulatory assets				13,815	13,861
Amounts being recovered through base rates [Member] | Subsidiaries [Member]
Regulatory Assets And Liabilities [Line Items]
Regulatory assets, current				13,815	13,861
Regulatory assets				13,815	13,861
Pension Costs [Member]
Regulatory Assets And Liabilities [Line Items]
Regulatory assets, non-current				114,887	149,374
Pension Costs [Member] | Subsidiaries [Member]
Regulatory Assets And Liabilities [Line Items]
Regulatory assets, non-current				114,887	149,374
Deferred Project Costs [Member]
Regulatory Assets And Liabilities [Line Items]
Regulatory assets, non-current					61,267
Deferred Project Costs [Member] | Subsidiaries [Member]
Regulatory Assets And Liabilities [Line Items]
Regulatory assets, non-current					61,267
Unamortized Carrying Charges And Certain Other Costs [Member]
Regulatory Assets And Liabilities [Line Items]
Regulatory assets, non-current				4,921	5,975
Unamortized Carrying Charges And Certain Other Costs [Member] | Subsidiaries [Member]
Regulatory Assets And Liabilities [Line Items]
Regulatory assets, non-current				4,921	5,975
Loss on Reacquired Debt [Member]
Regulatory Assets And Liabilities [Line Items]
Regulatory assets, non-current				15,703	17,018
Loss on Reacquired Debt [Member] | Subsidiaries [Member]
Regulatory Assets And Liabilities [Line Items]
Regulatory assets, non-current				15,703	17,018
Environmental Restoration Costs [Member]
Regulatory Assets And Liabilities [Line Items]
Regulatory assets, non-current				71,201	74,637
Environmental Restoration Costs [Member] | Subsidiaries [Member]
Regulatory Assets And Liabilities [Line Items]
Regulatory assets, non-current				71,201	74,637
Other Miscellaneous [Member]
Regulatory Assets And Liabilities [Line Items]
Regulatory assets, non-current				1,056	847
Other Miscellaneous [Member] | Subsidiaries [Member]
Regulatory Assets And Liabilities [Line Items]
Regulatory assets, non-current				1,056	847
Deferred MISO Non-fuel Costs [Member]
Regulatory Assets And Liabilities [Line Items]
Regulatory assets, non-current				47,875
Deferred MISO Non-fuel Costs [Member] | Subsidiaries [Member]
Regulatory Assets And Liabilities [Line Items]
Regulatory assets, non-current				47,875
COVID-19
Regulatory Assets And Liabilities [Line Items]
Regulatory assets, non-current				5,426	6,391
COVID-19 | Subsidiaries [Member]
Regulatory Assets And Liabilities [Line Items]
Regulatory assets, non-current				5,426	6,391
TDSIC projects
Regulatory Assets And Liabilities [Line Items]
Regulatory assets, non-current				8,540	2,747
TDSIC projects | Subsidiaries [Member]
Regulatory Assets And Liabilities [Line Items]
Regulatory assets, non-current				8,540	2,747
Petersburg Unit 1 retirement
Regulatory Assets And Liabilities [Line Items]
Regulatory assets, non-current				60,100	74,500
Petersburg Unit 1 retirement | Subsidiaries [Member]
Regulatory Assets And Liabilities [Line Items]
Regulatory assets, non-current				60,100	74,545
Petersburg Unit 2 retirement
Regulatory Assets And Liabilities [Line Items]
Regulatory assets, non-current				239,900
Petersburg Unit 2 retirement | Subsidiaries [Member]
Regulatory Assets And Liabilities [Line Items]
Regulatory assets, non-current				239,900
Hardy Hills Solar Project
Regulatory Assets And Liabilities [Line Items]
Regulatory assets, non-current				2,907	0
Hardy Hills Solar Project | Subsidiaries [Member]
Regulatory Assets And Liabilities [Line Items]
Regulatory assets, non-current				2,907	0
Petersburg Solar Project
Regulatory Assets And Liabilities [Line Items]
Regulatory assets, non-current				881	0
Petersburg Solar Project | Subsidiaries [Member]
Regulatory Assets And Liabilities [Line Items]
Regulatory assets, non-current				881	0
Fuel Costs
Regulatory Assets And Liabilities [Line Items]
Regulatory assets, non-current				83,513	0
Fuel Costs | Subsidiaries [Member]
Regulatory Assets And Liabilities [Line Items]
Regulatory assets, non-current				83,513	0
Petersburg Unit 1 retirement and 2 retirement costs
Regulatory Assets And Liabilities [Line Items]
Regulatory assets, non-current				300,067	$ 74,545
Petersburg Unit 1 retirement and 2 retirement costs | Subsidiaries [Member]
Regulatory Assets And Liabilities [Line Items]
Regulatory assets, non-current				$ 300,067
Rate Order total benefits to customers [Member]
Regulatory Assets And Liabilities [Line Items]
Approved Rate Order Benefits to Customers	$ 50,000
Rate Order total benefits to customers [Member] | Subsidiaries [Member]
Regulatory Assets And Liabilities [Line Items]
Approved Rate Order Benefits to Customers	50,000
Benchmark for annual wholesale margins [Member]
Regulatory Assets And Liabilities [Line Items]
Approved Rate Order Benefits to Customers	16,300
Benchmark for annual wholesale margins [Member] | Subsidiaries [Member]
Regulatory Assets And Liabilities [Line Items]
Approved Rate Order Benefits to Customers	16,300
Benchmark for annual capacity sales [Member]
Regulatory Assets And Liabilities [Line Items]
Approved Rate Order Benefits to Customers	11,300
Benchmark for annual capacity sales [Member] | Subsidiaries [Member]
Regulatory Assets And Liabilities [Line Items]
Approved Rate Order Benefits to Customers	11,300
Increase to Annual Depreciation Rate [Member]
Regulatory Assets And Liabilities [Line Items]
Public Utilities, Approved Rate Increase (Decrease), Amount	28,700
Increase to Annual Depreciation Rate [Member] | Subsidiaries [Member]
Regulatory Assets And Liabilities [Line Items]
Public Utilities, Approved Rate Increase (Decrease), Amount	$ 28,700