Receivables (Additional Attributes Of Receivables Sold Under The Agreement) (Details) (IPL [Member], USD $) In Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
IPL [Member]
Collections reinvested in receivables	$ 482.3	$ 518.4	$ 1,367.8	$ 925.5
Credit losses, net of recoveries	$ 3.4	$ 3.1	$ 7.9	$ 4.9