Common Equity And Preferred Stock (Common Stock Activity) (Details)	6 Months Ended
	Jun. 30, 2011
Common Equity And Preferred Stock
Shares outstanding, Jan. 1	110,893,901
Equity incentive plans	125,090
Other	(39,480)	[1]
Shares outstanding, June 30	110,979,511

[1] 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.