Common Equity (Tables)

12 Months Ended

Dec. 31, 2012

Schedule of Common Equity [Line Items]

Common Stock Activity

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

	2012		2011		2010
Shares outstanding, January 1	111,018,821		110,893,901		110,656,498
Equity-based compensation plans (Note 6(b))	20,195		164,400		260,316
Other (a)	(51,616	)	(39,480	)	(22,913	)
Shares outstanding, December 31	110,987,400		111,018,821		110,893,901

(a) Includes shares transferred from employees to Alliant Energy to satisfy tax withholding requirements in connection with the vesting of certain restricted stock under the equity-based compensation plans.

Schedule of Restricted Net Assets of Subsidiaries

As of December 31, the amount of net assets of IPL and WPL that were not available to be transferred to their parent company in the form of cash dividends without the consent of IPL’s and WPL’s regulatory authorities was as follows (in billions):

	2012		2011
IPL		$1.1		$1.0
WPL	1.5		1.3

Capital Transactions with Subsidiaries

IPL, WPL and Resources paid common stock dividends and repayments of capital to their parent company, Alliant Energy, as follows (in millions):

	IPL						WPL						Resources
	2012		2011		2010		2012		2011		2010		2012		2011		2010
Common stock dividends		$122.9		$73.4		$—		$112.0		$112.1		$109.5		$—		$—		$—
Repayments of capital	—		100.7		118.2		—		—		—		—		—		65.0
Total distributions from common equity		$122.9		$174.1		$118.2		$112.0		$112.1		$109.5		$—		$—		$65.0

Schedule of Capital Contributions

IPL, WPL, Resources and Corporate Services received capital contributions from their parent company, Alliant Energy, as follows (in millions):

	2012		2011		2010
IPL		$110.0		$54.0		$50.0
WPL	90.0		25.0		75.0
Resources	—		65.0		—
Corporate Services	30.0		—		—

IPL [Member]

Schedule of Common Equity [Line Items]

Schedule of Restricted Net Assets of Subsidiaries

As of December 31, the amount of net assets of IPL and WPL that were not available to be transferred to their parent company in the form of cash dividends without the consent of IPL’s and WPL’s regulatory authorities was as follows (in billions):

	2012		2011
IPL		$1.1		$1.0
WPL	1.5		1.3

Capital Transactions with Subsidiaries

IPL, WPL and Resources paid common stock dividends and repayments of capital to their parent company, Alliant Energy, as follows (in millions):

	IPL						WPL						Resources
	2012		2011		2010		2012		2011		2010		2012		2011		2010
Common stock dividends		$122.9		$73.4		$—		$112.0		$112.1		$109.5		$—		$—		$—
Repayments of capital	—		100.7		118.2		—		—		—		—		—		65.0
Total distributions from common equity		$122.9		$174.1		$118.2		$112.0		$112.1		$109.5		$—		$—		$65.0

Schedule of Capital Contributions

IPL, WPL, Resources and Corporate Services received capital contributions from their parent company, Alliant Energy, as follows (in millions):

	2012		2011		2010
IPL		$110.0		$54.0		$50.0
WPL	90.0		25.0		75.0
Resources	—		65.0		—
Corporate Services	30.0		—		—

WPL [Member]

Schedule of Common Equity [Line Items]

Schedule of Restricted Net Assets of Subsidiaries

As of December 31, the amount of net assets of IPL and WPL that were not available to be transferred to their parent company in the form of cash dividends without the consent of IPL’s and WPL’s regulatory authorities was as follows (in billions):

	2012		2011
IPL		$1.1		$1.0
WPL	1.5		1.3

Capital Transactions with Subsidiaries

IPL, WPL and Resources paid common stock dividends and repayments of capital to their parent company, Alliant Energy, as follows (in millions):

	IPL						WPL						Resources
	2012		2011		2010		2012		2011		2010		2012		2011		2010
Common stock dividends		$122.9		$73.4		$—		$112.0		$112.1		$109.5		$—		$—		$—
Repayments of capital	—		100.7		118.2		—		—		—		—		—		65.0
Total distributions from common equity		$122.9		$174.1		$118.2		$112.0		$112.1		$109.5		$—		$—		$65.0

Schedule of Capital Contributions

IPL, WPL, Resources and Corporate Services received capital contributions from their parent company, Alliant Energy, as follows (in millions):

	2012		2011		2010
IPL		$110.0		$54.0		$50.0
WPL	90.0		25.0		75.0
Resources	—		65.0		—
Corporate Services	30.0		—		—