Common Equity (Tables)

6 Months Ended

Jun. 30, 2019

Schedule of Capitalization, Equity [Line Items]

Common Share Activity

A summary of Alliant Energy’s common stock activity was as follows:

Shares outstanding, January 1, 2019	236,063,279
Equity forward agreements	1,090,300
Shareowner Direct Plan	268,755
Equity-based compensation plans	101,478
Other	(2,738	)
Shares outstanding, June 30, 2019	237,521,074

Changes in Shareowners' Equity

A summary of changes in shareowners’ equity was as follows (in millions):

Alliant Energy	Total Alliant Energy Common Equity
								Accumulated			Shares in			Cumulative
			Additional					Other			Deferred			Preferred
	Common		Paid-In		Retained			Comprehensive			Compensation			Stock		Total
	Stock		Capital		Earnings			Income (Loss)			Trust			of IPL		Equity
Three Months Ended June 30, 2019
Beginning balance, April 1		$2.4		$2,100.0		$2,587.3			$2.4			($9.7	)		$200.0		$4,882.4
Net income attributable to Alliant Energy common shareowners					94.6											94.6
Common stock dividends ($0.355 per share)					(84.1		)									(84.1		)
Shareowner Direct Plan issuances			6.0													6.0
Equity-based compensation plans and other			2.4								(0.3		)			2.1
Other comprehensive loss, net of tax								(1.4		)						(1.4		)
Ending balance, June 30		$2.4		$2,108.4		$2,597.8			$1.0			($10.0	)		$200.0		$4,899.6
Three Months Ended June 30, 2018
Beginning balance, April 1		$2.3		$1,851.4		$2,389.4			($0.5	)		($11.1	)		$200.0		$4,431.5
Net income attributable to Alliant Energy common shareowners					100.4											100.4
Common stock dividends ($0.335 per share)					(77.3		)									(77.3		)
At-the-market offering program and Shareowner Direct Plan issuances			93.8													93.8
Equity-based compensation plans and other			2.0								(0.3		)			1.7
Other comprehensive income, net of tax								0.6								0.6
Ending balance, June 30		$2.3		$1,947.2		$2,412.5			$0.1			($11.4	)		$200.0		$4,550.7

Alliant Energy	Total Alliant Energy Common Equity
								Accumulated			Shares in			Cumulative
			Additional					Other			Deferred			Preferred
	Common		Paid-In		Retained			Comprehensive			Compensation			Stock		Total
	Stock		Capital		Earnings			Income (Loss)			Trust			of IPL		Equity
Six Months Ended June 30, 2019
Beginning balance, January 1		$2.4		$2,045.5		$2,545.9			$1.7			($9.8	)		$200.0		$4,785.7
Net income attributable to Alliant Energy common shareowners					219.7											219.7
Common stock dividends ($0.71 per share)					(167.8		)									(167.8		)
Equity forward settlements and Shareowner Direct Plan issuances			60.6													60.6
Equity-based compensation plans and other			2.3								(0.2		)			2.1
Other comprehensive loss, net of tax								(0.7		)						(0.7		)
Ending balance, June 30		$2.4		$2,108.4		$2,597.8			$1.0			($10.0	)		$200.0		$4,899.6
Six Months Ended June 30, 2018
Beginning balance, January 1		$2.3		$1,845.5		$2,346.0			($0.5	)		($11.1	)		$200.0		$4,382.2
Net income attributable to Alliant Energy common shareowners					221.3											221.3
Common stock dividends ($0.67 per share)					(154.8		)									(154.8		)
At-the-market offering program and Shareowner Direct Plan issuances			100.1													100.1
Equity-based compensation plans and other			1.6								(0.3		)			1.3
Other comprehensive income, net of tax								0.6								0.6
Ending balance, June 30		$2.3		$1,947.2		$2,412.5			$0.1			($11.4	)		$200.0		$4,550.7

IPL	Total IPL Common Equity
			Additional					Cumulative
	Common		Paid-In		Retained			Preferred		Total
	Stock		Capital		Earnings			Stock		Equity
Three Months Ended June 30, 2019
Beginning balance, April 1		$33.4		$2,322.8		$785.8			$200.0		$3,342.0
Earnings available for common stock					45.0					45.0
Common stock dividends					(41.9		)			(41.9		)
Ending balance, June 30		$33.4		$2,322.8		$788.9			$200.0		$3,345.1
Three Months Ended June 30, 2018
Beginning balance, April 1		$33.4		$1,797.8		$683.3			$200.0		$2,714.5
Earnings available for common stock					51.7					51.7
Common stock dividends					(42.1		)			(42.1		)
Capital contributions from parent			130.0							130.0
Ending balance, June 30		$33.4		$1,927.8		$692.9			$200.0		$2,854.1

IPL	Total IPL Common Equity
			Additional					Cumulative
	Common		Paid-In		Retained			Preferred		Total
	Stock		Capital		Earnings			Stock		Equity
Six Months Ended June 30, 2019
Beginning balance, January 1		$33.4		$2,222.8		$774.5			$200.0		$3,230.7
Earnings available for common stock					98.3					98.3
Common stock dividends					(83.9		)			(83.9		)
Capital contributions from parent			100.0							100.0
Ending balance, June 30		$33.4		$2,322.8		$788.9			$200.0		$3,345.1
Six Months Ended June 30, 2018
Beginning balance, January 1		$33.4		$1,797.8		$678.5			$200.0		$2,709.7
Earnings available for common stock					98.4					98.4
Common stock dividends					(84.0		)			(84.0		)
Capital contributions from parent			130.0							130.0
Ending balance, June 30		$33.4		$1,927.8		$692.9			$200.0		$2,854.1

WPL			Additional					Total
	Common		Paid-In		Retained			Common
	Stock		Capital		Earnings			Equity
Three Months Ended June 30, 2019
Beginning balance, April 1		$66.2		$1,309.0		$804.0			$2,179.2
Earnings available for common stock					42.0			42.0
Common stock dividends					(36.0		)	(36.0		)
Ending balance, June 30		$66.2		$1,309.0		$810.0			$2,185.2
Three Months Ended June 30, 2018
Beginning balance, April 1		$66.2		$1,109.0		$725.3			$1,900.5
Earnings available for common stock					39.8			39.8
Common stock dividends					(35.1		)	(35.1		)
Capital contributions from parent			150.0					150.0
Ending balance, June 30		$66.2		$1,259.0		$730.0			$2,055.2

WPL			Additional					Total
	Common		Paid-In		Retained			Common
	Stock		Capital		Earnings			Equity
Six Months Ended June 30, 2019
Beginning balance, January 1		$66.2		$1,309.0		$774.3			$2,149.5
Earnings available for common stock					107.7			107.7
Common stock dividends					(72.0		)	(72.0		)
Ending balance, June 30		$66.2		$1,309.0		$810.0			$2,185.2
Six Months Ended June 30, 2018
Beginning balance, January 1		$66.2		$1,109.0		$706.3			$1,881.5
Earnings available for common stock					93.8			93.8
Common stock dividends					(70.1		)	(70.1		)
Capital contributions from parent			150.0					150.0
Ending balance, June 30		$66.2		$1,259.0		$730.0			$2,055.2

IPL [Member]

Schedule of Capitalization, Equity [Line Items]

Changes in Shareowners' Equity

A summary of changes in shareowners’ equity was as follows (in millions):

Alliant Energy	Total Alliant Energy Common Equity
								Accumulated			Shares in			Cumulative
			Additional					Other			Deferred			Preferred
	Common		Paid-In		Retained			Comprehensive			Compensation			Stock		Total
	Stock		Capital		Earnings			Income (Loss)			Trust			of IPL		Equity
Three Months Ended June 30, 2019
Beginning balance, April 1		$2.4		$2,100.0		$2,587.3			$2.4			($9.7	)		$200.0		$4,882.4
Net income attributable to Alliant Energy common shareowners					94.6											94.6
Common stock dividends ($0.355 per share)					(84.1		)									(84.1		)
Shareowner Direct Plan issuances			6.0													6.0
Equity-based compensation plans and other			2.4								(0.3		)			2.1
Other comprehensive loss, net of tax								(1.4		)						(1.4		)
Ending balance, June 30		$2.4		$2,108.4		$2,597.8			$1.0			($10.0	)		$200.0		$4,899.6
Three Months Ended June 30, 2018
Beginning balance, April 1		$2.3		$1,851.4		$2,389.4			($0.5	)		($11.1	)		$200.0		$4,431.5
Net income attributable to Alliant Energy common shareowners					100.4											100.4
Common stock dividends ($0.335 per share)					(77.3		)									(77.3		)
At-the-market offering program and Shareowner Direct Plan issuances			93.8													93.8
Equity-based compensation plans and other			2.0								(0.3		)			1.7
Other comprehensive income, net of tax								0.6								0.6
Ending balance, June 30		$2.3		$1,947.2		$2,412.5			$0.1			($11.4	)		$200.0		$4,550.7

Alliant Energy	Total Alliant Energy Common Equity
								Accumulated			Shares in			Cumulative
			Additional					Other			Deferred			Preferred
	Common		Paid-In		Retained			Comprehensive			Compensation			Stock		Total
	Stock		Capital		Earnings			Income (Loss)			Trust			of IPL		Equity
Six Months Ended June 30, 2019
Beginning balance, January 1		$2.4		$2,045.5		$2,545.9			$1.7			($9.8	)		$200.0		$4,785.7
Net income attributable to Alliant Energy common shareowners					219.7											219.7
Common stock dividends ($0.71 per share)					(167.8		)									(167.8		)
Equity forward settlements and Shareowner Direct Plan issuances			60.6													60.6
Equity-based compensation plans and other			2.3								(0.2		)			2.1
Other comprehensive loss, net of tax								(0.7		)						(0.7		)
Ending balance, June 30		$2.4		$2,108.4		$2,597.8			$1.0			($10.0	)		$200.0		$4,899.6
Six Months Ended June 30, 2018
Beginning balance, January 1		$2.3		$1,845.5		$2,346.0			($0.5	)		($11.1	)		$200.0		$4,382.2
Net income attributable to Alliant Energy common shareowners					221.3											221.3
Common stock dividends ($0.67 per share)					(154.8		)									(154.8		)
At-the-market offering program and Shareowner Direct Plan issuances			100.1													100.1
Equity-based compensation plans and other			1.6								(0.3		)			1.3
Other comprehensive income, net of tax								0.6								0.6
Ending balance, June 30		$2.3		$1,947.2		$2,412.5			$0.1			($11.4	)		$200.0		$4,550.7

IPL	Total IPL Common Equity
			Additional					Cumulative
	Common		Paid-In		Retained			Preferred		Total
	Stock		Capital		Earnings			Stock		Equity
Three Months Ended June 30, 2019
Beginning balance, April 1		$33.4		$2,322.8		$785.8			$200.0		$3,342.0
Earnings available for common stock					45.0					45.0
Common stock dividends					(41.9		)			(41.9		)
Ending balance, June 30		$33.4		$2,322.8		$788.9			$200.0		$3,345.1
Three Months Ended June 30, 2018
Beginning balance, April 1		$33.4		$1,797.8		$683.3			$200.0		$2,714.5
Earnings available for common stock					51.7					51.7
Common stock dividends					(42.1		)			(42.1		)
Capital contributions from parent			130.0							130.0
Ending balance, June 30		$33.4		$1,927.8		$692.9			$200.0		$2,854.1

IPL	Total IPL Common Equity
			Additional					Cumulative
	Common		Paid-In		Retained			Preferred		Total
	Stock		Capital		Earnings			Stock		Equity
Six Months Ended June 30, 2019
Beginning balance, January 1		$33.4		$2,222.8		$774.5			$200.0		$3,230.7
Earnings available for common stock					98.3					98.3
Common stock dividends					(83.9		)			(83.9		)
Capital contributions from parent			100.0							100.0
Ending balance, June 30		$33.4		$2,322.8		$788.9			$200.0		$3,345.1
Six Months Ended June 30, 2018
Beginning balance, January 1		$33.4		$1,797.8		$678.5			$200.0		$2,709.7
Earnings available for common stock					98.4					98.4
Common stock dividends					(84.0		)			(84.0		)
Capital contributions from parent			130.0							130.0
Ending balance, June 30		$33.4		$1,927.8		$692.9			$200.0		$2,854.1

WPL			Additional					Total
	Common		Paid-In		Retained			Common
	Stock		Capital		Earnings			Equity
Three Months Ended June 30, 2019
Beginning balance, April 1		$66.2		$1,309.0		$804.0			$2,179.2
Earnings available for common stock					42.0			42.0
Common stock dividends					(36.0		)	(36.0		)
Ending balance, June 30		$66.2		$1,309.0		$810.0			$2,185.2
Three Months Ended June 30, 2018
Beginning balance, April 1		$66.2		$1,109.0		$725.3			$1,900.5
Earnings available for common stock					39.8			39.8
Common stock dividends					(35.1		)	(35.1		)
Capital contributions from parent			150.0					150.0
Ending balance, June 30		$66.2		$1,259.0		$730.0			$2,055.2

WPL			Additional					Total
	Common		Paid-In		Retained			Common
	Stock		Capital		Earnings			Equity
Six Months Ended June 30, 2019
Beginning balance, January 1		$66.2		$1,309.0		$774.3			$2,149.5
Earnings available for common stock					107.7			107.7
Common stock dividends					(72.0		)	(72.0		)
Ending balance, June 30		$66.2		$1,309.0		$810.0			$2,185.2
Six Months Ended June 30, 2018
Beginning balance, January 1		$66.2		$1,109.0		$706.3			$1,881.5
Earnings available for common stock					93.8			93.8
Common stock dividends					(70.1		)	(70.1		)
Capital contributions from parent			150.0					150.0
Ending balance, June 30		$66.2		$1,259.0		$730.0			$2,055.2

WPL [Member]

Schedule of Capitalization, Equity [Line Items]

Changes in Shareowners' Equity

A summary of changes in shareowners’ equity was as follows (in millions):

Alliant Energy	Total Alliant Energy Common Equity
								Accumulated			Shares in			Cumulative
			Additional					Other			Deferred			Preferred
	Common		Paid-In		Retained			Comprehensive			Compensation			Stock		Total
	Stock		Capital		Earnings			Income (Loss)			Trust			of IPL		Equity
Three Months Ended June 30, 2019
Beginning balance, April 1		$2.4		$2,100.0		$2,587.3			$2.4			($9.7	)		$200.0		$4,882.4
Net income attributable to Alliant Energy common shareowners					94.6											94.6
Common stock dividends ($0.355 per share)					(84.1		)									(84.1		)
Shareowner Direct Plan issuances			6.0													6.0
Equity-based compensation plans and other			2.4								(0.3		)			2.1
Other comprehensive loss, net of tax								(1.4		)						(1.4		)
Ending balance, June 30		$2.4		$2,108.4		$2,597.8			$1.0			($10.0	)		$200.0		$4,899.6
Three Months Ended June 30, 2018
Beginning balance, April 1		$2.3		$1,851.4		$2,389.4			($0.5	)		($11.1	)		$200.0		$4,431.5
Net income attributable to Alliant Energy common shareowners					100.4											100.4
Common stock dividends ($0.335 per share)					(77.3		)									(77.3		)
At-the-market offering program and Shareowner Direct Plan issuances			93.8													93.8
Equity-based compensation plans and other			2.0								(0.3		)			1.7
Other comprehensive income, net of tax								0.6								0.6
Ending balance, June 30		$2.3		$1,947.2		$2,412.5			$0.1			($11.4	)		$200.0		$4,550.7

Alliant Energy	Total Alliant Energy Common Equity
								Accumulated			Shares in			Cumulative
			Additional					Other			Deferred			Preferred
	Common		Paid-In		Retained			Comprehensive			Compensation			Stock		Total
	Stock		Capital		Earnings			Income (Loss)			Trust			of IPL		Equity
Six Months Ended June 30, 2019
Beginning balance, January 1		$2.4		$2,045.5		$2,545.9			$1.7			($9.8	)		$200.0		$4,785.7
Net income attributable to Alliant Energy common shareowners					219.7											219.7
Common stock dividends ($0.71 per share)					(167.8		)									(167.8		)
Equity forward settlements and Shareowner Direct Plan issuances			60.6													60.6
Equity-based compensation plans and other			2.3								(0.2		)			2.1
Other comprehensive loss, net of tax								(0.7		)						(0.7		)
Ending balance, June 30		$2.4		$2,108.4		$2,597.8			$1.0			($10.0	)		$200.0		$4,899.6
Six Months Ended June 30, 2018
Beginning balance, January 1		$2.3		$1,845.5		$2,346.0			($0.5	)		($11.1	)		$200.0		$4,382.2
Net income attributable to Alliant Energy common shareowners					221.3											221.3
Common stock dividends ($0.67 per share)					(154.8		)									(154.8		)
At-the-market offering program and Shareowner Direct Plan issuances			100.1													100.1
Equity-based compensation plans and other			1.6								(0.3		)			1.3
Other comprehensive income, net of tax								0.6								0.6
Ending balance, June 30		$2.3		$1,947.2		$2,412.5			$0.1			($11.4	)		$200.0		$4,550.7

IPL	Total IPL Common Equity
			Additional					Cumulative
	Common		Paid-In		Retained			Preferred		Total
	Stock		Capital		Earnings			Stock		Equity
Three Months Ended June 30, 2019
Beginning balance, April 1		$33.4		$2,322.8		$785.8			$200.0		$3,342.0
Earnings available for common stock					45.0					45.0
Common stock dividends					(41.9		)			(41.9		)
Ending balance, June 30		$33.4		$2,322.8		$788.9			$200.0		$3,345.1
Three Months Ended June 30, 2018
Beginning balance, April 1		$33.4		$1,797.8		$683.3			$200.0		$2,714.5
Earnings available for common stock					51.7					51.7
Common stock dividends					(42.1		)			(42.1		)
Capital contributions from parent			130.0							130.0
Ending balance, June 30		$33.4		$1,927.8		$692.9			$200.0		$2,854.1

IPL	Total IPL Common Equity
			Additional					Cumulative
	Common		Paid-In		Retained			Preferred		Total
	Stock		Capital		Earnings			Stock		Equity
Six Months Ended June 30, 2019
Beginning balance, January 1		$33.4		$2,222.8		$774.5			$200.0		$3,230.7
Earnings available for common stock					98.3					98.3
Common stock dividends					(83.9		)			(83.9		)
Capital contributions from parent			100.0							100.0
Ending balance, June 30		$33.4		$2,322.8		$788.9			$200.0		$3,345.1
Six Months Ended June 30, 2018
Beginning balance, January 1		$33.4		$1,797.8		$678.5			$200.0		$2,709.7
Earnings available for common stock					98.4					98.4
Common stock dividends					(84.0		)			(84.0		)
Capital contributions from parent			130.0							130.0
Ending balance, June 30		$33.4		$1,927.8		$692.9			$200.0		$2,854.1

WPL			Additional					Total
	Common		Paid-In		Retained			Common
	Stock		Capital		Earnings			Equity
Three Months Ended June 30, 2019
Beginning balance, April 1		$66.2		$1,309.0		$804.0			$2,179.2
Earnings available for common stock					42.0			42.0
Common stock dividends					(36.0		)	(36.0		)
Ending balance, June 30		$66.2		$1,309.0		$810.0			$2,185.2
Three Months Ended June 30, 2018
Beginning balance, April 1		$66.2		$1,109.0		$725.3			$1,900.5
Earnings available for common stock					39.8			39.8
Common stock dividends					(35.1		)	(35.1		)
Capital contributions from parent			150.0					150.0
Ending balance, June 30		$66.2		$1,259.0		$730.0			$2,055.2

WPL			Additional					Total
	Common		Paid-In		Retained			Common
	Stock		Capital		Earnings			Equity
Six Months Ended June 30, 2019
Beginning balance, January 1		$66.2		$1,309.0		$774.3			$2,149.5
Earnings available for common stock					107.7			107.7
Common stock dividends					(72.0		)	(72.0		)
Ending balance, June 30		$66.2		$1,309.0		$810.0			$2,185.2
Six Months Ended June 30, 2018
Beginning balance, January 1		$66.2		$1,109.0		$706.3			$1,881.5
Earnings available for common stock					93.8			93.8
Common stock dividends					(70.1		)	(70.1		)
Capital contributions from parent			150.0					150.0
Ending balance, June 30		$66.2		$1,259.0		$730.0			$2,055.2