Segments Of Business

6 Months Ended

Jun. 30, 2018

Segment Reporting Information [Line Items]

SEGMENTS OF BUSINESS

In the fourth quarter of 2017, Alliant Energy and WPL modified the segment reporting related to ATC Holdings, consistent with information used by their chief operating decision maker to evaluate performance and allocate resources. As of December 31, 2017, ATC Holdings are no longer included in Alliant Energy’s utility electric operations reportable segment or WPL’s electric operations reportable segment. As a result, all prior period amounts impacted by this change were reclassified to conform to the new presentation. Alliant Energy’s related amounts were reclassified from “Electric Utility” to “ATC Holdings, Non-Utility, Parent and Other” in the table below. There was no resulting change to WPL’s segment reporting for the three and six months ended June 30, 2017.

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



									ATC Holdings,		Alliant
	Utility								Non-Utility,		Energy
	Electric		Gas		Other		Total		Parent and Other		Consolidated
	(in millions)
Three Months Ended June 30, 2018
Revenues		$726.3		$68.6		$10.7		$805.6		$10.5		$816.1
Operating income	134.8		5.4		0.9		141.1		10.1		151.2
Net income attributable to Alliant Energy common shareowners							91.5		8.9		100.4
Three Months Ended June 30, 2017
Revenues		$680.9		$62.6		$11.5		$755.0		$10.3		$765.3
Operating income	139.3		4.4		0.6		144.3		9.4		153.7
Net income attributable to Alliant Energy common shareowners							80.9		13.4		94.3



									ATC Holdings,		Alliant
	Utility								Non-Utility,		Energy
	Electric		Gas		Other		Total		Parent and Other		Consolidated
	(in millions)
Six Months Ended June 30, 2018
Revenues		$1,435.0		$254.2		$23.9		$1,713.1		$19.3		$1,732.4
Operating income	261.5		36.9		2.3		300.7		16.2		316.9
Net income attributable to Alliant Energy common shareowners							192.2		29.1		221.3
Six Months Ended June 30, 2017
Revenues		$1,358.5		$216.9		$23.2		$1,598.6		$20.6		$1,619.2
Operating income	250.2		33.0		1.0		284.2		16.7		300.9
Amounts attributable to Alliant Energy common shareowners:
Income from continuing operations, net of tax							163.6		29.7		193.3
Income from discontinued operations, net of tax							—		1.4		1.4
Net income							163.6		31.1		194.7

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 June 30, 2018
Revenues		$422.1		$42.2		$10.5		$474.8
Operating income	73.5		2.5		1.7		77.7
Earnings available for common stock							51.7
Three Months Ended June 30, 2017
Revenues		$372.4		$36.7		$11.1		$420.2
Operating income	63.9		2.6		1.6		68.1
Earnings available for common stock							42.8
Six Months Ended June 30, 2018
Revenues		$827.8		$150.3		$22.5		$1,000.6
Operating income	131.0		19.4		2.9		153.3
Earnings available for common stock							98.4
Six Months Ended June 30, 2017
Revenues		$728.6		$119.8		$22.3		$870.7
Operating income	99.2		17.2		3.0		119.4
Earnings available for common stock							80.0

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 June 30, 2018
Revenues		$304.2		$26.4		$0.2			$330.8
Operating income (loss)	61.3		2.9		(0.8		)	63.4
Earnings available for common stock								39.8
Three Months Ended June 30, 2017
Revenues		$308.5		$25.9		$0.4			$334.8
Operating income (loss)	75.4		1.8		(1.0		)	76.2
Earnings available for common stock								38.1
Six Months Ended June 30, 2018
Revenues		$607.2		$103.9		$1.4			$712.5
Operating income (loss)	130.5		17.5		(0.6		)	147.4
Earnings available for common stock								93.8
Six Months Ended June 30, 2017
Revenues		$629.9		$97.1		$0.9			$727.9
Operating income (loss)	151.0		15.8		(2.0		)	164.8
Earnings available for common stock								83.6

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. Intersegment revenues were not material to Alliant Energy’s operations.



									ATC Holdings,		Alliant
	Utility								Non-Utility,		Energy
	Electric		Gas		Other		Total		Parent and Other		Consolidated
	(in millions)
Three Months Ended June 30, 2018
Revenues		$726.3		$68.6		$10.7		$805.6		$10.5		$816.1
Operating income	134.8		5.4		0.9		141.1		10.1		151.2
Net income attributable to Alliant Energy common shareowners							91.5		8.9		100.4
Three Months Ended June 30, 2017
Revenues		$680.9		$62.6		$11.5		$755.0		$10.3		$765.3
Operating income	139.3		4.4		0.6		144.3		9.4		153.7
Net income attributable to Alliant Energy common shareowners							80.9		13.4		94.3



									ATC Holdings,		Alliant
	Utility								Non-Utility,		Energy
	Electric		Gas		Other		Total		Parent and Other		Consolidated
	(in millions)
Six Months Ended June 30, 2018
Revenues		$1,435.0		$254.2		$23.9		$1,713.1		$19.3		$1,732.4
Operating income	261.5		36.9		2.3		300.7		16.2		316.9
Net income attributable to Alliant Energy common shareowners							192.2		29.1		221.3
Six Months Ended June 30, 2017
Revenues		$1,358.5		$216.9		$23.2		$1,598.6		$20.6		$1,619.2
Operating income	250.2		33.0		1.0		284.2		16.7		300.9
Amounts attributable to Alliant Energy common shareowners:
Income from continuing operations, net of tax							163.6		29.7		193.3
Income from discontinued operations, net of tax							—		1.4		1.4
Net income							163.6		31.1		194.7

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 June 30, 2018
Revenues		$422.1		$42.2		$10.5		$474.8
Operating income	73.5		2.5		1.7		77.7
Earnings available for common stock							51.7
Three Months Ended June 30, 2017
Revenues		$372.4		$36.7		$11.1		$420.2
Operating income	63.9		2.6		1.6		68.1
Earnings available for common stock							42.8
Six Months Ended June 30, 2018
Revenues		$827.8		$150.3		$22.5		$1,000.6
Operating income	131.0		19.4		2.9		153.3
Earnings available for common stock							98.4
Six Months Ended June 30, 2017
Revenues		$728.6		$119.8		$22.3		$870.7
Operating income	99.2		17.2		3.0		119.4
Earnings available for common stock							80.0

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 June 30, 2018
Revenues		$304.2		$26.4		$0.2			$330.8
Operating income (loss)	61.3		2.9		(0.8		)	63.4
Earnings available for common stock								39.8
Three Months Ended June 30, 2017
Revenues		$308.5		$25.9		$0.4			$334.8
Operating income (loss)	75.4		1.8		(1.0		)	76.2
Earnings available for common stock								38.1
Six Months Ended June 30, 2018
Revenues		$607.2		$103.9		$1.4			$712.5
Operating income (loss)	130.5		17.5		(0.6		)	147.4
Earnings available for common stock								93.8
Six Months Ended June 30, 2017
Revenues		$629.9		$97.1		$0.9			$727.9
Operating income (loss)	151.0		15.8		(2.0		)	164.8
Earnings available for common stock								83.6

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. Intersegment revenues were not material to Alliant Energy’s operations.



									ATC Holdings,		Alliant
	Utility								Non-Utility,		Energy
	Electric		Gas		Other		Total		Parent and Other		Consolidated
	(in millions)
Three Months Ended June 30, 2018
Revenues		$726.3		$68.6		$10.7		$805.6		$10.5		$816.1
Operating income	134.8		5.4		0.9		141.1		10.1		151.2
Net income attributable to Alliant Energy common shareowners							91.5		8.9		100.4
Three Months Ended June 30, 2017
Revenues		$680.9		$62.6		$11.5		$755.0		$10.3		$765.3
Operating income	139.3		4.4		0.6		144.3		9.4		153.7
Net income attributable to Alliant Energy common shareowners							80.9		13.4		94.3



									ATC Holdings,		Alliant
	Utility								Non-Utility,		Energy
	Electric		Gas		Other		Total		Parent and Other		Consolidated
	(in millions)
Six Months Ended June 30, 2018
Revenues		$1,435.0		$254.2		$23.9		$1,713.1		$19.3		$1,732.4
Operating income	261.5		36.9		2.3		300.7		16.2		316.9
Net income attributable to Alliant Energy common shareowners							192.2		29.1		221.3
Six Months Ended June 30, 2017
Revenues		$1,358.5		$216.9		$23.2		$1,598.6		$20.6		$1,619.2
Operating income	250.2		33.0		1.0		284.2		16.7		300.9
Amounts attributable to Alliant Energy common shareowners:
Income from continuing operations, net of tax							163.6		29.7		193.3
Income from discontinued operations, net of tax							—		1.4		1.4
Net income							163.6		31.1		194.7

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 June 30, 2018
Revenues		$422.1		$42.2		$10.5		$474.8
Operating income	73.5		2.5		1.7		77.7
Earnings available for common stock							51.7
Three Months Ended June 30, 2017
Revenues		$372.4		$36.7		$11.1		$420.2
Operating income	63.9		2.6		1.6		68.1
Earnings available for common stock							42.8
Six Months Ended June 30, 2018
Revenues		$827.8		$150.3		$22.5		$1,000.6
Operating income	131.0		19.4		2.9		153.3
Earnings available for common stock							98.4
Six Months Ended June 30, 2017
Revenues		$728.6		$119.8		$22.3		$870.7
Operating income	99.2		17.2		3.0		119.4
Earnings available for common stock							80.0

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 June 30, 2018
Revenues		$304.2		$26.4		$0.2			$330.8
Operating income (loss)	61.3		2.9		(0.8		)	63.4
Earnings available for common stock								39.8
Three Months Ended June 30, 2017
Revenues		$308.5		$25.9		$0.4			$334.8
Operating income (loss)	75.4		1.8		(1.0		)	76.2
Earnings available for common stock								38.1
Six Months Ended June 30, 2018
Revenues		$607.2		$103.9		$1.4			$712.5
Operating income (loss)	130.5		17.5		(0.6		)	147.4
Earnings available for common stock								93.8
Six Months Ended June 30, 2017
Revenues		$629.9		$97.1		$0.9			$727.9
Operating income (loss)	151.0		15.8		(2.0		)	164.8
Earnings available for common stock								83.6