Segments Of Business

9 Months Ended

Sep. 30, 2012

Segment Reporting Information [Line Items]

Segments Of Business

SEGMENTS OF BUSINESS

Alliant Energy - Certain financial information relating to Alliant Energy’s business segments is as follows. As of September 30, 2012, Alliant Energy’s RMT business qualified as assets and liabilities held for sale. The operating results of RMT have been separately classified and reported as discontinued operations in Alliant Energy’s Condensed Consolidated Statements of Income. As a result, Alliant Energy no longer reports “Non-regulated - RMT” segment information. Intersegment revenues were not material to Alliant Energy’s operations.

	Utility									Non-Regulated,			Alliant Energy
	Electric		Gas			Other		Total		Parent and Other			Consolidated
	(in millions)
Three Months Ended September 30, 2012
Operating revenues		$815.3		$46.8			$12.2		$874.3		$13.3			$887.6
Operating income	203.1		0.8			1.5		205.4		8.3			213.7
Amounts attributable to Alliant Energy common shareowners:
Income (loss) from continuing operations, net of tax								159.2		(10.2		)	149.0
Income from discontinued operations, net of tax								—		1.7			1.7
Net income (loss) attributable to Alliant Energy common shareowners								159.2		(8.5		)	150.7
Three Months Ended September 30, 2011
Operating revenues		$796.9		$46.4			$15.8		$859.1		$11.8			$870.9
Operating income (loss)	206.1		(2.8		)	0.1		203.4		6.0			209.4
Amounts attributable to Alliant Energy common shareowners:
Income (loss) from continuing operations, net of tax								148.9		(12.0		)	136.9
Loss from discontinued operations, net of tax								—		(14.9		)	(14.9		)
Net income (loss) attributable to Alliant Energy common shareowners								148.9		(26.9		)	122.0

	Utility									Non-Regulated,			Alliant Energy
	Electric		Gas		Other			Total		Parent and Other			Consolidated
	(in millions)
Nine Months Ended September 30, 2012
Operating revenues		$2,000.3		$263.9		$39.7			$2,303.9		$39.7			$2,343.6
Operating income	354.0		32.1		4.7			390.8		27.3			418.1
Amounts attributable to Alliant Energy common shareowners:
Income from continuing operations, net of tax								237.4		16.4			253.8
Loss from discontinued operations, net of tax								—		(2.3		)	(2.3		)
Net income attributable to Alliant Energy common shareowners								237.4		14.1			251.5
Nine Months Ended September 30, 2011
Operating revenues		$2,037.7		$342.5		$45.8			$2,426.0		$34.6			$2,460.6
Operating income (loss)	357.6		34.0		(2.3		)	389.3		18.0			407.3
Amounts attributable to Alliant Energy common shareowners:
Income from continuing operations, net of tax								236.0		23.2			259.2
Loss from discontinued operations, net of tax								—		(12.6		)	(12.6		)
Net income attributable to Alliant Energy common shareowners								236.0		10.6			246.6

IPL - Certain financial information relating to IPL’s business segments is as follows. Intersegment revenues were not material to IPL’s operations.

	Electric		Gas			Other		Total
	(in millions)
Three Months Ended September 30, 2012
Operating revenues		$456.6		$29.6			$11.5		$497.7
Operating income	109.5		0.6			1.9		112.0
Earnings available for common stock								103.3
Three Months Ended September 30, 2011
Operating revenues		$443.2		$27.5			$13.8		$484.5
Operating income (loss)	117.5		(1.3		)	0.3		116.5
Earnings available for common stock								98.3
Nine Months Ended September 30, 2012
Operating revenues		$1,070.7		$149.2			$37.2		$1,257.1
Operating income	149.3		15.6			6.4		171.3
Earnings available for common stock								115.2
Nine Months Ended September 30, 2011
Operating revenues		$1,097.3		$198.1			$40.7		$1,336.1
Operating income	162.3		15.1			4.7		182.1
Earnings available for common stock								117.7

WPL - Certain financial information relating to WPL’s business segments is as follows. Intersegment revenues were not material to WPL’s operations.

	Electric		Gas			Other			Total
	(in millions)
Three Months Ended September 30, 2012
Operating revenues		$358.7		$17.2			$0.7			$376.6
Operating income	93.6		0.2			(0.4		)	93.4
Earnings available for common stock									55.9
Three Months Ended September 30, 2011
Operating revenues		$353.7		$18.9			$2.0			$374.6
Operating income (loss)	88.6		(1.5		)	(0.2		)	86.9
Earnings available for common stock									50.6
Nine Months Ended September 30, 2012
Operating revenues		$929.6		$114.7			$2.5			$1,046.8
Operating income (loss)	204.7		16.5			(1.7		)	219.5
Earnings available for common stock									122.2
Nine Months Ended September 30, 2011
Operating revenues		$940.4		$144.4			$5.1			$1,089.9
Operating income (loss)	195.3		18.9			(7.0		)	207.2
Earnings available for common stock									118.3

IPL [Member]

Segment Reporting Information [Line Items]

Segments Of Business

SEGMENTS OF BUSINESS

Alliant Energy - Certain financial information relating to Alliant Energy’s business segments is as follows. As of September 30, 2012, Alliant Energy’s RMT business qualified as assets and liabilities held for sale. The operating results of RMT have been separately classified and reported as discontinued operations in Alliant Energy’s Condensed Consolidated Statements of Income. As a result, Alliant Energy no longer reports “Non-regulated - RMT” segment information. Intersegment revenues were not material to Alliant Energy’s operations.

	Utility									Non-Regulated,			Alliant Energy
	Electric		Gas			Other		Total		Parent and Other			Consolidated
	(in millions)
Three Months Ended September 30, 2012
Operating revenues		$815.3		$46.8			$12.2		$874.3		$13.3			$887.6
Operating income	203.1		0.8			1.5		205.4		8.3			213.7
Amounts attributable to Alliant Energy common shareowners:
Income (loss) from continuing operations, net of tax								159.2		(10.2		)	149.0
Income from discontinued operations, net of tax								—		1.7			1.7
Net income (loss) attributable to Alliant Energy common shareowners								159.2		(8.5		)	150.7
Three Months Ended September 30, 2011
Operating revenues		$796.9		$46.4			$15.8		$859.1		$11.8			$870.9
Operating income (loss)	206.1		(2.8		)	0.1		203.4		6.0			209.4
Amounts attributable to Alliant Energy common shareowners:
Income (loss) from continuing operations, net of tax								148.9		(12.0		)	136.9
Loss from discontinued operations, net of tax								—		(14.9		)	(14.9		)
Net income (loss) attributable to Alliant Energy common shareowners								148.9		(26.9		)	122.0

	Utility									Non-Regulated,			Alliant Energy
	Electric		Gas		Other			Total		Parent and Other			Consolidated
	(in millions)
Nine Months Ended September 30, 2012
Operating revenues		$2,000.3		$263.9		$39.7			$2,303.9		$39.7			$2,343.6
Operating income	354.0		32.1		4.7			390.8		27.3			418.1
Amounts attributable to Alliant Energy common shareowners:
Income from continuing operations, net of tax								237.4		16.4			253.8
Loss from discontinued operations, net of tax								—		(2.3		)	(2.3		)
Net income attributable to Alliant Energy common shareowners								237.4		14.1			251.5
Nine Months Ended September 30, 2011
Operating revenues		$2,037.7		$342.5		$45.8			$2,426.0		$34.6			$2,460.6
Operating income (loss)	357.6		34.0		(2.3		)	389.3		18.0			407.3
Amounts attributable to Alliant Energy common shareowners:
Income from continuing operations, net of tax								236.0		23.2			259.2
Loss from discontinued operations, net of tax								—		(12.6		)	(12.6		)
Net income attributable to Alliant Energy common shareowners								236.0		10.6			246.6

IPL - Certain financial information relating to IPL’s business segments is as follows. Intersegment revenues were not material to IPL’s operations.

	Electric		Gas			Other		Total
	(in millions)
Three Months Ended September 30, 2012
Operating revenues		$456.6		$29.6			$11.5		$497.7
Operating income	109.5		0.6			1.9		112.0
Earnings available for common stock								103.3
Three Months Ended September 30, 2011
Operating revenues		$443.2		$27.5			$13.8		$484.5
Operating income (loss)	117.5		(1.3		)	0.3		116.5
Earnings available for common stock								98.3
Nine Months Ended September 30, 2012
Operating revenues		$1,070.7		$149.2			$37.2		$1,257.1
Operating income	149.3		15.6			6.4		171.3
Earnings available for common stock								115.2
Nine Months Ended September 30, 2011
Operating revenues		$1,097.3		$198.1			$40.7		$1,336.1
Operating income	162.3		15.1			4.7		182.1
Earnings available for common stock								117.7

WPL - Certain financial information relating to WPL’s business segments is as follows. Intersegment revenues were not material to WPL’s operations.

	Electric		Gas			Other			Total
	(in millions)
Three Months Ended September 30, 2012
Operating revenues		$358.7		$17.2			$0.7			$376.6
Operating income	93.6		0.2			(0.4		)	93.4
Earnings available for common stock									55.9
Three Months Ended September 30, 2011
Operating revenues		$353.7		$18.9			$2.0			$374.6
Operating income (loss)	88.6		(1.5		)	(0.2		)	86.9
Earnings available for common stock									50.6
Nine Months Ended September 30, 2012
Operating revenues		$929.6		$114.7			$2.5			$1,046.8
Operating income (loss)	204.7		16.5			(1.7		)	219.5
Earnings available for common stock									122.2
Nine Months Ended September 30, 2011
Operating revenues		$940.4		$144.4			$5.1			$1,089.9
Operating income (loss)	195.3		18.9			(7.0		)	207.2
Earnings available for common stock									118.3

WPL [Member]

Segment Reporting Information [Line Items]

Segments Of Business

SEGMENTS OF BUSINESS

Alliant Energy - Certain financial information relating to Alliant Energy’s business segments is as follows. As of September 30, 2012, Alliant Energy’s RMT business qualified as assets and liabilities held for sale. The operating results of RMT have been separately classified and reported as discontinued operations in Alliant Energy’s Condensed Consolidated Statements of Income. As a result, Alliant Energy no longer reports “Non-regulated - RMT” segment information. Intersegment revenues were not material to Alliant Energy’s operations.

	Utility									Non-Regulated,			Alliant Energy
	Electric		Gas			Other		Total		Parent and Other			Consolidated
	(in millions)
Three Months Ended September 30, 2012
Operating revenues		$815.3		$46.8			$12.2		$874.3		$13.3			$887.6
Operating income	203.1		0.8			1.5		205.4		8.3			213.7
Amounts attributable to Alliant Energy common shareowners:
Income (loss) from continuing operations, net of tax								159.2		(10.2		)	149.0
Income from discontinued operations, net of tax								—		1.7			1.7
Net income (loss) attributable to Alliant Energy common shareowners								159.2		(8.5		)	150.7
Three Months Ended September 30, 2011
Operating revenues		$796.9		$46.4			$15.8		$859.1		$11.8			$870.9
Operating income (loss)	206.1		(2.8		)	0.1		203.4		6.0			209.4
Amounts attributable to Alliant Energy common shareowners:
Income (loss) from continuing operations, net of tax								148.9		(12.0		)	136.9
Loss from discontinued operations, net of tax								—		(14.9		)	(14.9		)
Net income (loss) attributable to Alliant Energy common shareowners								148.9		(26.9		)	122.0

	Utility									Non-Regulated,			Alliant Energy
	Electric		Gas		Other			Total		Parent and Other			Consolidated
	(in millions)
Nine Months Ended September 30, 2012
Operating revenues		$2,000.3		$263.9		$39.7			$2,303.9		$39.7			$2,343.6
Operating income	354.0		32.1		4.7			390.8		27.3			418.1
Amounts attributable to Alliant Energy common shareowners:
Income from continuing operations, net of tax								237.4		16.4			253.8
Loss from discontinued operations, net of tax								—		(2.3		)	(2.3		)
Net income attributable to Alliant Energy common shareowners								237.4		14.1			251.5
Nine Months Ended September 30, 2011
Operating revenues		$2,037.7		$342.5		$45.8			$2,426.0		$34.6			$2,460.6
Operating income (loss)	357.6		34.0		(2.3		)	389.3		18.0			407.3
Amounts attributable to Alliant Energy common shareowners:
Income from continuing operations, net of tax								236.0		23.2			259.2
Loss from discontinued operations, net of tax								—		(12.6		)	(12.6		)
Net income attributable to Alliant Energy common shareowners								236.0		10.6			246.6

IPL - Certain financial information relating to IPL’s business segments is as follows. Intersegment revenues were not material to IPL’s operations.

	Electric		Gas			Other		Total
	(in millions)
Three Months Ended September 30, 2012
Operating revenues		$456.6		$29.6			$11.5		$497.7
Operating income	109.5		0.6			1.9		112.0
Earnings available for common stock								103.3
Three Months Ended September 30, 2011
Operating revenues		$443.2		$27.5			$13.8		$484.5
Operating income (loss)	117.5		(1.3		)	0.3		116.5
Earnings available for common stock								98.3
Nine Months Ended September 30, 2012
Operating revenues		$1,070.7		$149.2			$37.2		$1,257.1
Operating income	149.3		15.6			6.4		171.3
Earnings available for common stock								115.2
Nine Months Ended September 30, 2011
Operating revenues		$1,097.3		$198.1			$40.7		$1,336.1
Operating income	162.3		15.1			4.7		182.1
Earnings available for common stock								117.7

WPL - Certain financial information relating to WPL’s business segments is as follows. Intersegment revenues were not material to WPL’s operations.

	Electric		Gas			Other			Total
	(in millions)
Three Months Ended September 30, 2012
Operating revenues		$358.7		$17.2			$0.7			$376.6
Operating income	93.6		0.2			(0.4		)	93.4
Earnings available for common stock									55.9
Three Months Ended September 30, 2011
Operating revenues		$353.7		$18.9			$2.0			$374.6
Operating income (loss)	88.6		(1.5		)	(0.2		)	86.9
Earnings available for common stock									50.6
Nine Months Ended September 30, 2012
Operating revenues		$929.6		$114.7			$2.5			$1,046.8
Operating income (loss)	204.7		16.5			(1.7		)	219.5
Earnings available for common stock									122.2
Nine Months Ended September 30, 2011
Operating revenues		$940.4		$144.4			$5.1			$1,089.9
Operating income (loss)	195.3		18.9			(7.0		)	207.2
Earnings available for common stock									118.3