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Benefit Plans (Recognized Compensation Expense And Income Tax Benefits) (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
Compensation expense | $ 16 | $ 26 | $ 17
Income tax benefits | 4 | 7 | 5
IPL [Member] |  |  |
Compensation expense | 9 | 15 | 9
Income tax benefits | 2 | 4 | 3
WPL [Member] |  |  |
Compensation expense | 6 | 10 | 7
Income tax benefits | $ 2 | $ 3 | $ 2

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