Goodwill And Other Intangible Assets (Tables)

9 Months Ended

Sep. 30, 2011

Goodwill And Other Intangible Assets

Gross Carrying Amount And Accumulated Amortization Expense

	Alliant Energy				IPL				WPL
	Sep. 30,		Dec. 31,		Sep. 30,		Dec. 31,		Sep. 30,		Dec. 31,
	2011		2010		2011		2010		2011		2010
Gross carrying amount	$	12.6	$	50.9	$	12.1	$	47.0	$	0.5	$	3.9
Accumulated amortization		10.7		16.5		10.2		13.1		0.5		3.4

Amortization Expense

	Alliant Energy								IPL								WPL
	Three Months				Nine Months				Three Months				Nine Months				Three Months				Nine Months
	2011		2010		2011		2010		2011		2010		2011		2010		2011		2010		2011		2010
Amortization expense	$	3.7	$	3.9	$	10.7	$	13.4	$	3.7	$	3.6	$	10.2	$	10.1	$	—	$	0.3	$	0.5	$	3.3