Income Taxes (Tables)

6 Months Ended

Jun. 30, 2012

Income Tax [Line Items]

Schedule Of Effective Income Tax Rates

The effective income tax rates shown in the following table for the three and six months ended June 30 were computed by dividing income tax expense (benefit) by income from continuing operations before income taxes.

	Three Months				Six Months
	2012		2011		2012		2011
Alliant Energy	19.5	%	(25.9	%)	28.3	%	7.8	%
IPL	(12.0	%)	(233.3	%)	22.6	%	3.4	%
WPL	34.6	%	31.1	%	39.4	%	32.0	%

Production Tax Credits (Net Of State Tax Impacts)

For the three and six months ended June 30, production tax credits (net of state tax impacts) resulting from these wind projects were as follows (in millions):

	Three Months				Six Months
	2012		2011		2012		2011
Cedar Ridge (WPL)		$1.0		$1.1		$2.3		$2.6
Bent Tree - Phase I (WPL)	2.7		2.8		4.2		5.3
Subtotal (WPL)	3.7		3.9		6.5		7.9
Whispering Willow - East (IPL)	3.1		3.6		6.7		6.4
		$6.8		$7.5		$13.2		$14.3

Alliant Energy [Member]

Income Tax [Line Items]

Summary Of Tax Credit Carryforwards

At June 30, 2012, tax carryforwards and associated deferred tax assets and expiration dates were estimated as follows (in millions):

Alliant Energy	Carryforward Amount			Deferred Tax Assets			Earliest Expiration Date
Federal net operating losses		$1,026			$352		2028
Federal net operating losses offset - uncertain tax positions	(57		)	(20		)
State net operating losses	756			39			2014
State net operating losses offset - uncertain tax positions	(27		)	(2		)
Federal tax credits	122			121			2022
					$490

IPL [Member]

Income Tax [Line Items]

Summary Of Tax Credit Carryforwards

IPL	Carryforward Amount			Deferred Tax Assets			Earliest Expiration Date
Federal net operating losses		$472			$162		2028
Federal net operating losses offset - uncertain tax positions	(26		)	(9		)
State net operating losses	171			10			2022
Federal tax credits	32			32			2022
					$195

WPL [Member]

Income Tax [Line Items]

Summary Of Tax Credit Carryforwards

WPL	Carryforward Amount			Deferred Tax Assets			Earliest Expiration Date
Federal net operating losses		$437			$150		2028
Federal net operating losses offset - uncertain tax positions	(31		)	(11		)
State net operating losses	142			7			2022
State net operating losses offset - uncertain tax positions	(27		)	(2		)
Federal tax credits	33			33			2022
					$177