Segments Of Business (Tables)

12 Months Ended

Dec. 31, 2012

Segment Reporting Information [Line Items]

Schedule of Segments of Business

Certain financial information relating to Alliant Energy’s business segments, products and services and geographic information was as follows (in millions):

	Utility										Non-Regulated,			Alliant Energy
2012	Electric			Gas		Other		Total			Parent and Other			Consolidated
Operating revenues		$2,589.3			$396.3		$56.7		$3,042.3			$52.2			$3,094.5
Depreciation and amortization	299.3			29.1		1.4		329.8			2.6			332.4
Operating income	426.2			51.5		7.4		485.1			34.6			519.7
Interest expense, net of AFUDC								136.8			(2.0		)	134.8
Equity (income) loss from unconsolidated investments, net	(42.1		)	—		—		(42.1		)	0.8			(41.3		)
Interest income and other								(0.3		)	(3.7		)	(4.0		)
Income taxes								74.8			14.6			89.4
Income from continuing operations, net of tax								315.9			24.9			340.8
Loss from discontinued operations, net of tax								—			(5.1		)	(5.1		)
Net income								315.9			19.8			335.7
Preferred dividends								15.9			—			15.9
Net income attributable to Alliant Energy common shareowners								300.0			19.8			319.8
Total assets	8,438.8			814.8		966.0		10,219.6			565.9			10,785.5
Investments in equity method subsidiaries	264.3			—		—		264.3			2.3			266.6
Construction and acquisition expenditures	994.0			31.4		0.1		1,025.5			132.6			1,158.1

	Utility											Non-Regulated,			Alliant Energy
2011	Electric			Gas		Other			Total			Parent and Other			Consolidated
Operating revenues		$2,635.8			$476.7		$62.0			$3,174.5			$46.9			$3,221.4
Depreciation and amortization	289.0			28.4		1.8			319.2			1.8			321.0
Operating income (loss)	444.2			47.8		(3.2		)	488.8			24.5			513.3
Interest expense, net of AFUDC									146.6			(0.3		)	146.3
Equity income from unconsolidated investments, net	(38.7		)	—		—			(38.7		)	(0.6		)	(39.3		)
Interest income and other									(0.2		)	(4.1		)	(4.3		)
Income tax expense (benefit)									78.3			(9.1		)	69.2
Income from continuing operations, net of tax									302.8			38.6			341.4
Loss from discontinued operations, net of tax									—			(19.5		)	(19.5		)
Net income									302.8			19.1			321.9
Preferred dividends									18.3			—			18.3
Net income attributable to Alliant Energy common shareowners									284.5			19.1			303.6
Total assets	7,524.5			831.9		781.1			9,137.5			550.4			9,687.9
Investments in equity method subsidiaries	246.5			—		—			246.5			3.1			249.6
Construction and acquisition expenditures	542.7			38.0		27.4			608.1			65.3			673.4

	Utility											Non-Regulated,			Alliant Energy
2010	Electric			Gas		Other			Total			Parent and Other			Consolidated
Operating revenues		$2,674.2			$480.6		$64.6			$3,219.4			$42.7			$3,262.1
Depreciation and amortization	255.1			25.2		5.3			285.6			1.7			287.3
Operating income (loss)	489.8			53.4		(2.5		)	540.7			19.3			560.0
Interest expense, net of AFUDC									142.8			2.0			144.8
Equity income from unconsolidated investments, net	(37.8		)	—		—			(37.8		)	(0.3		)	(38.1		)
Interest income and other									(0.6		)	(4.0		)	(4.6		)
Income taxes									140.6			7.1			147.7
Income from continuing operations, net of tax									295.7			14.5			310.2
Loss from discontinued operations, net of tax									—			(3.9		)	(3.9		)
Net income									295.7			10.6			306.3
Preferred dividends									18.7			—			18.7
Net income attributable to Alliant Energy common shareowners									277.0			10.6			287.6
Total assets	7,227.2			817.6		782.4			8,827.2			455.7			9,282.9
Investments in equity method subsidiaries	236.0			—		—			236.0			2.5			238.5
Construction and acquisition expenditures	729.1			39.9		64.3			833.3			33.6			866.9

Schedule of Products and Services

Products and Services - Alliant Energy’s consolidated operating revenues by segment were as follows:

	2012		2011		2010
Utility electric operations	84	%	82	%	82	%
Utility gas operations	13	%	15	%	15	%
Utility other	2	%	2	%	2	%
Other	1	%	1	%	1	%
	100	%	100	%	100	%

IPL [Member]

Segment Reporting Information [Line Items]

Schedule of Segments of Business

Certain financial information relating to IPL’s business segments was as follows (in millions):

2012	Electric		Gas		Other		Total
Operating revenues		$1,371.1		$226.7		$52.5		$1,650.3
Depreciation and amortization	171.2		16.3		1.4		188.9
Operating income	166.2		24.2		9.9		200.3
Interest expense, net of AFUDC							70.1
Interest income and other							(0.2		)
Income tax benefit							(19.8		)
Net income							150.2
Preferred dividends							12.6
Earnings available for common stock							137.6
Total assets	4,500.9		479.5		476.6		5,457.0
Construction and acquisition expenditures	291.0		16.4		0.1		307.5

2011	Electric		Gas		Other		Total
Operating revenues		$1,408.3		$276.3		$55.5		$1,740.1
Depreciation and amortization	161.3		16.0		1.8		179.1
Operating income	181.6		20.6		6.2		208.4
Interest expense, net of AFUDC							72.9
Interest income and other							(0.2		)
Income tax benefit							(3.6		)
Net income							139.3
Preferred dividends							15.0
Earnings available for common stock							124.3
Total assets	4,208.2		471.1		414.2		5,093.5
Construction and acquisition expenditures	245.6		21.2		26.9		293.7

2010	Electric		Gas		Other			Total
Operating revenues		$1,464.3		$274.3		$57.2		$1,795.8
Depreciation and amortization	157.1		14.6		5.3			177.0
Operating income (loss)	239.7		23.6		(1.4		)	261.9
Interest expense, net of AFUDC								76.7
Interest income and other								(0.5	)
Income taxes								42.3
Net income								143.4
Preferred dividends								15.4
Earnings available for common stock								128.0
Total assets	4,025.3		460.3		452.0			4,937.6
Construction and acquisition expenditures	298.8		20.0		64.0			382.8

WPL [Member]

Segment Reporting Information [Line Items]

Schedule of Segments of Business

Certain financial information relating to WPL’s business segments was as follows (in millions):

2012	Electric			Gas		Other			Total
Operating revenues		$1,218.2			$169.6		$4.2			$1,392.0
Depreciation and amortization	128.1			12.8		—			140.9
Operating income (loss)	260.0			27.3		(2.5		)	284.8
Interest expense, net of AFUDC									66.7
Equity income from unconsolidated investments	(42.1		)	—		—			(42.1		)
Interest income and other									(0.1		)
Income taxes									94.6
Net income									165.7
Preferred dividends									3.3
Earnings available for common stock									162.4
Total assets	3,937.9			335.3		489.4			4,762.6
Investments in equity method subsidiaries	264.3			—		—			264.3
Construction and acquisition expenditures	703.0			15.0		—			718.0

2011	Electric	Gas		Other		Total
Operating revenues	$1,227.5		$200.4		$6.5		$1,434.4
Depreciation and amortization	127.7	12.4		—		140.1
Operating income (loss)	262.6	27.2		(9.4)		280.4
Interest expense, net of AFUDC						73.7
Equity income from unconsolidated investments	(38.7)	—		—		(38.7		)
Income taxes						81.9
Net income						163.5
Preferred dividends						3.3
Earnings available for common stock						160.2
Total assets	3,316.3	360.8		366.9		4,044.0
Investments in equity method subsidiaries	246.5	—		—		246.5
Construction and acquisition expenditures	297.1	16.8		0.5		314.4

2010	Electric	Gas		Other		Total
Operating revenues	$1,209.9		$206.3		$7.4		$1,423.6
Depreciation and amortization	98.0	10.6		—		108.6
Operating income (loss)	250.1	29.8		(1.1)		278.8
Interest expense, net of AFUDC						66.1
Equity income from unconsolidated investments	(37.8)	—		—		(37.8		)
Interest income and other						(0.1		)
Income taxes						98.3
Net income						152.3
Preferred dividends						3.3
Earnings available for common stock						149.0
Total assets	3,201.9	357.3		330.4		3,889.6
Investments in equity method subsidiaries	236.0	—		—		236.0
Construction and acquisition expenditures	430.3	19.9		0.3		450.5