Common Equity (Tables)

9 Months Ended

Sep. 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	3,790,300
Shareowner Direct Plan	390,630
Equity-based compensation plans	101,478
Other	(2,738	)
Shares outstanding, September 30, 2019	240,342,949

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 September 30, 2019
Beginning balance, July 1		$2.4		$2,108.4			$2,597.8			$1.0			($10.0	)		$200.0		$4,899.6
Net income attributable to Alliant Energy common shareowners						226.0											226.0
Common stock dividends ($0.355 per share)						(84.7		)									(84.7		)
Equity forward settlements and Shareowner Direct Plan issuances			124.8														124.8
Equity-based compensation plans and other			3.7									(0.2		)			3.5
Ending balance, September 30		$2.4		$2,236.9			$2,739.1			$1.0			($10.2	)		$200.0		$5,169.2
Three Months Ended September 30, 2018
Beginning balance, July 1		$2.3		$1,947.2			$2,412.5			$0.1			($11.4	)		$200.0		$4,550.7
Net income attributable to Alliant Energy common shareowners						205.5											205.5
Common stock dividends ($0.335 per share)						(78.5		)									(78.5		)
At-the-market offering program and Shareowner Direct Plan issuances	0.1		91.1														91.2
Equity-based compensation plans and other			(0.1		)							1.9					1.8
Other comprehensive loss, net of tax									(0.3		)						(0.3		)
Ending balance, September 30		$2.4		$2,038.2			$2,539.5			($0.2	)		($9.5	)		$200.0		$4,770.4

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
Nine Months Ended September 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					445.7											445.7
Common stock dividends ($1.065 per share)					(252.5		)									(252.5		)
Equity forward settlements and Shareowner Direct Plan issuances			185.4													185.4
Equity-based compensation plans and other			6.0								(0.4		)			5.6
Other comprehensive loss, net of tax								(0.7		)						(0.7		)
Ending balance, September 30		$2.4		$2,236.9		$2,739.1			$1.0			($10.2	)		$200.0		$5,169.2
Nine Months Ended September 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					426.8											426.8
Common stock dividends ($1.005 per share)					(233.3		)									(233.3		)
At-the-market offering program and Shareowner Direct Plan issuances	0.1		191.2													191.3
Equity-based compensation plans and other			1.5								1.6					3.1
Other comprehensive income, net of tax								0.3								0.3
Ending balance, September 30		$2.4		$2,038.2		$2,539.5			($0.2	)		($9.5	)		$200.0		$4,770.4

IPL	Total IPL Common Equity
			Additional					Cumulative
	Common		Paid-In		Retained			Preferred		Total
	Stock		Capital		Earnings			Stock		Equity
Three Months Ended September 30, 2019
Beginning balance, July 1		$33.4		$2,322.8		$788.9			$200.0		$3,345.1
Earnings available for common stock					141.1					141.1
Common stock dividends					(42.1		)			(42.1		)
Ending balance, September 30		$33.4		$2,322.8		$887.9			$200.0		$3,444.1
Three Months Ended September 30, 2018
Beginning balance, July 1		$33.4		$1,927.8		$692.9			$200.0		$2,854.1
Earnings available for common stock					126.5					126.5
Common stock dividends					(41.9		)			(41.9		)
Capital contributions from parent			100.0							100.0
Ending balance, September 30		$33.4		$2,027.8		$777.5			$200.0		$3,038.7

IPL	Total IPL Common Equity
			Additional					Cumulative
	Common		Paid-In		Retained			Preferred		Total
	Stock		Capital		Earnings			Stock		Equity
Nine Months Ended September 30, 2019
Beginning balance, January 1		$33.4		$2,222.8		$774.5			$200.0		$3,230.7
Earnings available for common stock					239.4					239.4
Common stock dividends					(126.0		)			(126.0		)
Capital contributions from parent			100.0							100.0
Ending balance, September 30		$33.4		$2,322.8		$887.9			$200.0		$3,444.1
Nine Months Ended September 30, 2018
Beginning balance, January 1		$33.4		$1,797.8		$678.5			$200.0		$2,709.7
Earnings available for common stock					224.9					224.9
Common stock dividends					(125.9		)			(125.9		)
Capital contributions from parent			230.0							230.0
Ending balance, September 30		$33.4		$2,027.8		$777.5			$200.0		$3,038.7

WPL			Additional					Total
	Common		Paid-In		Retained			Common
	Stock		Capital		Earnings			Equity
Three Months Ended September 30, 2019
Beginning balance, July 1		$66.2		$1,309.0		$810.0			$2,185.2
Earnings available for common stock					75.5			75.5
Common stock dividends					(35.9		)	(35.9		)
Capital contributions from parent			100.0					100.0
Ending balance, September 30		$66.2		$1,409.0		$849.6			$2,324.8
Three Months Ended September 30, 2018
Beginning balance, July 1		$66.2		$1,259.0		$730.0			$2,055.2
Earnings available for common stock					76.3			76.3
Common stock dividends					(34.9		)	(34.9		)
Capital contributions from parent			50.0					50.0
Ending balance, September 30		$66.2		$1,309.0		$771.4			$2,146.6

WPL			Additional					Total
	Common		Paid-In		Retained			Common
	Stock		Capital		Earnings			Equity
Nine Months Ended September 30, 2019
Beginning balance, January 1		$66.2		$1,309.0		$774.3			$2,149.5
Earnings available for common stock					183.2			183.2
Common stock dividends					(107.9		)	(107.9		)
Capital contributions from parent			100.0					100.0
Ending balance, September 30		$66.2		$1,409.0		$849.6			$2,324.8
Nine Months Ended September 30, 2018
Beginning balance, January 1		$66.2		$1,109.0		$706.3			$1,881.5
Earnings available for common stock					170.1			170.1
Common stock dividends					(105.0		)	(105.0		)
Capital contributions from parent			200.0					200.0
Ending balance, September 30		$66.2		$1,309.0		$771.4			$2,146.6

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 September 30, 2019
Beginning balance, July 1		$2.4		$2,108.4			$2,597.8			$1.0			($10.0	)		$200.0		$4,899.6
Net income attributable to Alliant Energy common shareowners						226.0											226.0
Common stock dividends ($0.355 per share)						(84.7		)									(84.7		)
Equity forward settlements and Shareowner Direct Plan issuances			124.8														124.8
Equity-based compensation plans and other			3.7									(0.2		)			3.5
Ending balance, September 30		$2.4		$2,236.9			$2,739.1			$1.0			($10.2	)		$200.0		$5,169.2
Three Months Ended September 30, 2018
Beginning balance, July 1		$2.3		$1,947.2			$2,412.5			$0.1			($11.4	)		$200.0		$4,550.7
Net income attributable to Alliant Energy common shareowners						205.5											205.5
Common stock dividends ($0.335 per share)						(78.5		)									(78.5		)
At-the-market offering program and Shareowner Direct Plan issuances	0.1		91.1														91.2
Equity-based compensation plans and other			(0.1		)							1.9					1.8
Other comprehensive loss, net of tax									(0.3		)						(0.3		)
Ending balance, September 30		$2.4		$2,038.2			$2,539.5			($0.2	)		($9.5	)		$200.0		$4,770.4

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
Nine Months Ended September 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					445.7											445.7
Common stock dividends ($1.065 per share)					(252.5		)									(252.5		)
Equity forward settlements and Shareowner Direct Plan issuances			185.4													185.4
Equity-based compensation plans and other			6.0								(0.4		)			5.6
Other comprehensive loss, net of tax								(0.7		)						(0.7		)
Ending balance, September 30		$2.4		$2,236.9		$2,739.1			$1.0			($10.2	)		$200.0		$5,169.2
Nine Months Ended September 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					426.8											426.8
Common stock dividends ($1.005 per share)					(233.3		)									(233.3		)
At-the-market offering program and Shareowner Direct Plan issuances	0.1		191.2													191.3
Equity-based compensation plans and other			1.5								1.6					3.1
Other comprehensive income, net of tax								0.3								0.3
Ending balance, September 30		$2.4		$2,038.2		$2,539.5			($0.2	)		($9.5	)		$200.0		$4,770.4

IPL	Total IPL Common Equity
			Additional					Cumulative
	Common		Paid-In		Retained			Preferred		Total
	Stock		Capital		Earnings			Stock		Equity
Three Months Ended September 30, 2019
Beginning balance, July 1		$33.4		$2,322.8		$788.9			$200.0		$3,345.1
Earnings available for common stock					141.1					141.1
Common stock dividends					(42.1		)			(42.1		)
Ending balance, September 30		$33.4		$2,322.8		$887.9			$200.0		$3,444.1
Three Months Ended September 30, 2018
Beginning balance, July 1		$33.4		$1,927.8		$692.9			$200.0		$2,854.1
Earnings available for common stock					126.5					126.5
Common stock dividends					(41.9		)			(41.9		)
Capital contributions from parent			100.0							100.0
Ending balance, September 30		$33.4		$2,027.8		$777.5			$200.0		$3,038.7

IPL	Total IPL Common Equity
			Additional					Cumulative
	Common		Paid-In		Retained			Preferred		Total
	Stock		Capital		Earnings			Stock		Equity
Nine Months Ended September 30, 2019
Beginning balance, January 1		$33.4		$2,222.8		$774.5			$200.0		$3,230.7
Earnings available for common stock					239.4					239.4
Common stock dividends					(126.0		)			(126.0		)
Capital contributions from parent			100.0							100.0
Ending balance, September 30		$33.4		$2,322.8		$887.9			$200.0		$3,444.1
Nine Months Ended September 30, 2018
Beginning balance, January 1		$33.4		$1,797.8		$678.5			$200.0		$2,709.7
Earnings available for common stock					224.9					224.9
Common stock dividends					(125.9		)			(125.9		)
Capital contributions from parent			230.0							230.0
Ending balance, September 30		$33.4		$2,027.8		$777.5			$200.0		$3,038.7

WPL			Additional					Total
	Common		Paid-In		Retained			Common
	Stock		Capital		Earnings			Equity
Three Months Ended September 30, 2019
Beginning balance, July 1		$66.2		$1,309.0		$810.0			$2,185.2
Earnings available for common stock					75.5			75.5
Common stock dividends					(35.9		)	(35.9		)
Capital contributions from parent			100.0					100.0
Ending balance, September 30		$66.2		$1,409.0		$849.6			$2,324.8
Three Months Ended September 30, 2018
Beginning balance, July 1		$66.2		$1,259.0		$730.0			$2,055.2
Earnings available for common stock					76.3			76.3
Common stock dividends					(34.9		)	(34.9		)
Capital contributions from parent			50.0					50.0
Ending balance, September 30		$66.2		$1,309.0		$771.4			$2,146.6

WPL			Additional					Total
	Common		Paid-In		Retained			Common
	Stock		Capital		Earnings			Equity
Nine Months Ended September 30, 2019
Beginning balance, January 1		$66.2		$1,309.0		$774.3			$2,149.5
Earnings available for common stock					183.2			183.2
Common stock dividends					(107.9		)	(107.9		)
Capital contributions from parent			100.0					100.0
Ending balance, September 30		$66.2		$1,409.0		$849.6			$2,324.8
Nine Months Ended September 30, 2018
Beginning balance, January 1		$66.2		$1,109.0		$706.3			$1,881.5
Earnings available for common stock					170.1			170.1
Common stock dividends					(105.0		)	(105.0		)
Capital contributions from parent			200.0					200.0
Ending balance, September 30		$66.2		$1,309.0		$771.4			$2,146.6

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 September 30, 2019
Beginning balance, July 1		$2.4		$2,108.4			$2,597.8			$1.0			($10.0	)		$200.0		$4,899.6
Net income attributable to Alliant Energy common shareowners						226.0											226.0
Common stock dividends ($0.355 per share)						(84.7		)									(84.7		)
Equity forward settlements and Shareowner Direct Plan issuances			124.8														124.8
Equity-based compensation plans and other			3.7									(0.2		)			3.5
Ending balance, September 30		$2.4		$2,236.9			$2,739.1			$1.0			($10.2	)		$200.0		$5,169.2
Three Months Ended September 30, 2018
Beginning balance, July 1		$2.3		$1,947.2			$2,412.5			$0.1			($11.4	)		$200.0		$4,550.7
Net income attributable to Alliant Energy common shareowners						205.5											205.5
Common stock dividends ($0.335 per share)						(78.5		)									(78.5		)
At-the-market offering program and Shareowner Direct Plan issuances	0.1		91.1														91.2
Equity-based compensation plans and other			(0.1		)							1.9					1.8
Other comprehensive loss, net of tax									(0.3		)						(0.3		)
Ending balance, September 30		$2.4		$2,038.2			$2,539.5			($0.2	)		($9.5	)		$200.0		$4,770.4

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
Nine Months Ended September 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					445.7											445.7
Common stock dividends ($1.065 per share)					(252.5		)									(252.5		)
Equity forward settlements and Shareowner Direct Plan issuances			185.4													185.4
Equity-based compensation plans and other			6.0								(0.4		)			5.6
Other comprehensive loss, net of tax								(0.7		)						(0.7		)
Ending balance, September 30		$2.4		$2,236.9		$2,739.1			$1.0			($10.2	)		$200.0		$5,169.2
Nine Months Ended September 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					426.8											426.8
Common stock dividends ($1.005 per share)					(233.3		)									(233.3		)
At-the-market offering program and Shareowner Direct Plan issuances	0.1		191.2													191.3
Equity-based compensation plans and other			1.5								1.6					3.1
Other comprehensive income, net of tax								0.3								0.3
Ending balance, September 30		$2.4		$2,038.2		$2,539.5			($0.2	)		($9.5	)		$200.0		$4,770.4

IPL	Total IPL Common Equity
			Additional					Cumulative
	Common		Paid-In		Retained			Preferred		Total
	Stock		Capital		Earnings			Stock		Equity
Three Months Ended September 30, 2019
Beginning balance, July 1		$33.4		$2,322.8		$788.9			$200.0		$3,345.1
Earnings available for common stock					141.1					141.1
Common stock dividends					(42.1		)			(42.1		)
Ending balance, September 30		$33.4		$2,322.8		$887.9			$200.0		$3,444.1
Three Months Ended September 30, 2018
Beginning balance, July 1		$33.4		$1,927.8		$692.9			$200.0		$2,854.1
Earnings available for common stock					126.5					126.5
Common stock dividends					(41.9		)			(41.9		)
Capital contributions from parent			100.0							100.0
Ending balance, September 30		$33.4		$2,027.8		$777.5			$200.0		$3,038.7

IPL	Total IPL Common Equity
			Additional					Cumulative
	Common		Paid-In		Retained			Preferred		Total
	Stock		Capital		Earnings			Stock		Equity
Nine Months Ended September 30, 2019
Beginning balance, January 1		$33.4		$2,222.8		$774.5			$200.0		$3,230.7
Earnings available for common stock					239.4					239.4
Common stock dividends					(126.0		)			(126.0		)
Capital contributions from parent			100.0							100.0
Ending balance, September 30		$33.4		$2,322.8		$887.9			$200.0		$3,444.1
Nine Months Ended September 30, 2018
Beginning balance, January 1		$33.4		$1,797.8		$678.5			$200.0		$2,709.7
Earnings available for common stock					224.9					224.9
Common stock dividends					(125.9		)			(125.9		)
Capital contributions from parent			230.0							230.0
Ending balance, September 30		$33.4		$2,027.8		$777.5			$200.0		$3,038.7

WPL			Additional					Total
	Common		Paid-In		Retained			Common
	Stock		Capital		Earnings			Equity
Three Months Ended September 30, 2019
Beginning balance, July 1		$66.2		$1,309.0		$810.0			$2,185.2
Earnings available for common stock					75.5			75.5
Common stock dividends					(35.9		)	(35.9		)
Capital contributions from parent			100.0					100.0
Ending balance, September 30		$66.2		$1,409.0		$849.6			$2,324.8
Three Months Ended September 30, 2018
Beginning balance, July 1		$66.2		$1,259.0		$730.0			$2,055.2
Earnings available for common stock					76.3			76.3
Common stock dividends					(34.9		)	(34.9		)
Capital contributions from parent			50.0					50.0
Ending balance, September 30		$66.2		$1,309.0		$771.4			$2,146.6

WPL			Additional					Total
	Common		Paid-In		Retained			Common
	Stock		Capital		Earnings			Equity
Nine Months Ended September 30, 2019
Beginning balance, January 1		$66.2		$1,309.0		$774.3			$2,149.5
Earnings available for common stock					183.2			183.2
Common stock dividends					(107.9		)	(107.9		)
Capital contributions from parent			100.0					100.0
Ending balance, September 30		$66.2		$1,409.0		$849.6			$2,324.8
Nine Months Ended September 30, 2018
Beginning balance, January 1		$66.2		$1,109.0		$706.3			$1,881.5
Earnings available for common stock					170.1			170.1
Common stock dividends					(105.0		)	(105.0		)
Capital contributions from parent			200.0					200.0
Ending balance, September 30		$66.2		$1,309.0		$771.4			$2,146.6