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Receivables (Receivables Sold Under The Agreement) (Details) - USD ($) $ in Millions | Dec. 31, 2019 | Dec. 31, 2018
--- | --- | ---
Accounts Receivable [Line Items] |  |
Fair value of deferred proceeds | $ 187.7 | $ 119.4
IPL [Member] |  |
Accounts Receivable [Line Items] |  |
Fair value of deferred proceeds | 187.7 | 119.4
Financing Receivable [Member] | IPL [Member] |  |
Accounts Receivable [Line Items] |  |
Customer accounts receivable | 124.7 | 140.1
Unbilled utility revenues | 95.5 | 97.1
Other receivables | 0.9 | 0.1
Receivables sold to third party | 221.1 | 237.3
Less: cash proceeds | 27.0 | 108.0
Deferred proceeds | 194.1 | 129.3
Less: allowance for doubtful accounts | 6.4 | 9.9
Fair value of deferred proceeds | 187.7 | 119.4
Outstanding receivables, past due | $ 26.0 | $ 35.5

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