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Benefit Plans (Narrative) (Details) $ in Millions | 9 Months Ended
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Sep. 30, 2025 USD ($) shares
Defined Benefit Plan Disclosure [Line Items] |
Unrecognized compensation cost | $ 17
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 | $ 8
IPL [Member] | Minimum [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Unrecognized compensation cost recognized over a weighted average period | 1 year
IPL [Member] | Maximum [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Unrecognized compensation cost recognized over a weighted average period | 2 years
WPL [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Unrecognized compensation cost | $ 8
WPL [Member] | Minimum [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Unrecognized compensation cost recognized over a weighted average period | 1 year
WPL [Member] | Maximum [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Unrecognized compensation cost recognized over a weighted average period | 2 years
Omnibus Incentive Plan [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Shares included in diluted earnings per share (in shares) | shares | 598,077

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