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v3.19.3.a.u2

Debt (Other Short-Term Borrowings) (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2019 | Dec. 31, 2018
Debt Instrument [Line Items] |  |
Maximum amount outstanding (based on daily outstanding balances) | $ 600.6 | $ 446.5
Average amount outstanding (based on daily outstanding balances) | $ 453.5 | $ 221.4
Weighted average interest rates | 2.50% | 2.20%
IPL [Member] |  |
Debt Instrument [Line Items] |  |
Maximum amount outstanding (based on daily outstanding balances) | $ 50.4 | $ 50.4
Average amount outstanding (based on daily outstanding balances) | $ 0.1 | $ 1.5
Weighted average interest rates | 2.80% | 2.30%
WPL [Member] |  |
Debt Instrument [Line Items] |  |
Maximum amount outstanding (based on daily outstanding balances) | $ 195.1 | $ 126.0
Average amount outstanding (based on daily outstanding balances) | $ 92.6 | $ 36.6
Weighted average interest rates | 2.40% | 2.10%

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