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Income Taxes (Schedule Of Components Of Income Tax) (Details) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Current tax expense (benefit):      
Federal $ 1 $ (7) $ (1)
State 8 24 (5)
Deferred tax expense (benefit):      
Federal 22 70 68
State 8 42 30
Production tax credits (95) (55) (30)
Investment tax credits (1) (1) (1)
Income tax expense (benefit) (57) 69 48
IPL's tax benefit riders [Member]      
Current tax expense (benefit):      
IPL's tax benefit riders 0 (4) (13)
IPL [Member]      
Current tax expense (benefit):      
Federal 6 (11) 15
State (1) 24 (7)
Deferred tax expense (benefit):      
Federal 30 26 10
State (2) 31 7
Production tax credits (80) (42) (14)
Investment tax credits 0 0 (1)
Income tax expense (benefit) (47) 24 (3)
IPL [Member] | IPL's tax benefit riders [Member]      
Current tax expense (benefit):      
IPL's tax benefit riders 0 (4) (13)
WPL [Member]      
Current tax expense (benefit):      
Federal (11) 12 (9)
State 7 13 (5)
Deferred tax expense (benefit):      
Federal (9) 31 44
State 10 6 22
Production tax credits (15) (13) (15)
Investment tax credits (1) 0 (1)
Income tax expense (benefit) $ (19) $ 49 $ 36