Receivables (Receivables Sold Under The Agreement) (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Receivables [Line Items]
Fair value of deferred proceeds	$ 194.1	$ 187.7
IPL [Member]
Receivables [Line Items]
Fair value of deferred proceeds	194.1	187.7
Receivables Sold [Member] | IPL [Member]
Receivables [Line Items]
Customer accounts receivable	113.5	124.7
Unbilled utility revenues	92.3	95.5
Other receivables	0.4	0.9
Receivables sold to third party	206.2	221.1
Less: cash proceeds	1.0	27.0
Deferred proceeds	205.2	194.1
Less: allowance for expected credit losses	11.1	6.4
Fair value of deferred proceeds	$ 194.1	$ 187.7