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Redeemable Stock of Subsidiaries (Narrative) (Details)
$ / shares in Units, $ in Millions
12 Months Ended
Dec. 31, 2020
USD ($)
quarter
series
$ / shares
Dec. 31, 2019
USD ($)
Dec. 31, 2018
USD ($)
Temporary Equity [Line Items]      
Temporary Equity, Accretion to Redemption Value $ 4 $ 6  
Temporary equity carrying amount 872 888 $ 879
Temporary Equity, Other Changes 0 10  
Temporary Equity, Net Income 8 (7)  
Colon [Domain]      
Temporary Equity [Line Items]      
Redeemable Noncontrolling Interest, Equity, Common, Carrying Amount [1] 194 210  
Temporary Equity, Other Changes 0 10  
IPALCO Enterprises, Inc. [Member]      
Temporary Equity [Line Items]      
Redeemable Noncontrolling Interest, Equity, Common, Carrying Amount 618 618  
IPL Subsidiary      
Temporary Equity [Line Items]      
Redeemable Noncontrolling Interest, Equity, Preferred, Carrying Amount 60 60  
Temporary equity carrying amount $ 60 60  
Number of preferred stock series | series 5    
Temporary equity annual dividend requirement $ 3 3  
Number of consecutive quarters without paid dividends to invoke board of directors election rule | quarter 4    
IPL Subsidiary | Minimum      
Temporary Equity [Line Items]      
Temporary equity, redemption price per share | $ / shares $ 100    
IPL Subsidiary | Maximum      
Temporary Equity [Line Items]      
Temporary equity, redemption price per share | $ / shares $ 118    
Other Comprehensive Income (Loss) [Member]      
Temporary Equity [Line Items]      
Temporary Equity, Other Changes $ (28) $ 0  
[1] Characteristics of quotas are similar to common stock.