Common Equity And Noncontrolling Interest (Tables)

12 Months Ended

Dec. 31, 2011

Common Equity [Abstract]

Common Stock Activity

	2011			2010			2009
Shares outstanding, Jan. 1		110,893,901			110,656,498			110,449,099
Equity incentive plans (Note 6(b))		164,400			260,316			240,889
Other (a)		(39,480	)		(22,913	)		(33,490	)
Shares outstanding, Dec. 31		111,018,821			110,893,901			110,656,498

(a) Includes shares transferred from employees to Alliant Energy to satisfy tax withholding requirements in connection with the vesting of certain restricted stock under the equity incentive plans.

Schedule Of Restricted Net Assets Of Subsidiaries

	2011		2010
IPL	$	1.0	$	1.0
WPL		1.3		1.3

Capital Transactions With Subsidiaries

	IPL						WPL						Resources
	2011		2010		2009		2011		2010		2009		2011		2010		2009
Common stock dividends	$	73.4	$	—	$	—	$	112.1	$	109.5	$	91.0	$	—	$	—	$	—
Repayments of capital		100.7		118.2		106.1		—		—		—		—		65.0		100.0
Total distributions from common equity	$	174.1	$	118.2	$	106.1	$	112.1	$	109.5	$	91.0	$	—	$	65.0	$	100.0

Schedule Of Capital Contributions

	IPL						WPL						Resources
	2011		2010		2009		2011		2010		2009		2011		2010		2009
Capital contributions	$	54.0	$	50.0	$	150.0	$	25.0	$	75.0	$	100.0	$	65.0	$	—	$	—