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Benefit Plans (Narrative) (Details) $ in Millions | 9 Months Ended
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Sep. 30, 2020 USD ($) shares
Defined Benefit Plan Disclosure [Line Items] |
Unrecognized compensation cost | $ 7
Minimum [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Unrecognized compensation cost recognized over a weighted average period | 1 year
Maximum [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Unrecognized compensation cost recognized over a weighted average period | 2 years
IPL [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Unrecognized compensation cost | $ 4
WPL [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Unrecognized compensation cost | $ 3
Omnibus Incentive Plan [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Shares included in diluted earnings per share (in shares) | shares | 276,070

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