Investments (Tables)

12 Months Ended

Dec. 31, 2012

Investment [Line Items]

Unconsolidated Equity Investments

Alliant Energy’s and WPL’s unconsolidated investments accounted for under the equity method of accounting are as follows (in millions):

	Ownership	Carrying Value at
	Interest at	December 31,				Equity (Income) / Loss
	December 31, 2012	2012		2011		2012			2011			2010
Alliant Energy
ATC (a)	16%		$257.0		$238.8		($41.3	)		($37.8	)		($36.9	)
Wisconsin River Power Company	50%	7.3		7.7		(0.8		)	(0.9		)	(0.9		)
Other	Various	2.3		3.1		0.8			(0.6		)	(0.3		)
			$266.6		$249.6		($41.3	)		($39.3	)		($38.1	)
WPL
ATC (a)	16%		$257.0		$238.8		($41.3	)		($37.8	)		($36.9	)
Wisconsin River Power Company	50%	7.3		7.7		(0.8		)	(0.9		)	(0.9		)
			$264.3		$246.5		($42.1	)		($38.7	)		($37.8	)

(a) Alliant Energy and WPL have the ability to exercise significant influence over ATC’s financial and operating policies through their participation on ATC’s Board of Directors. Refer to Note 19 for information regarding related party transactions with ATC.

Summary Financial Information

Summary aggregate financial information from the financial statements of these investments is as follows (in millions):

	Alliant Energy						WPL
	2012		2011		2010		2012		2011		2010
Operating revenues		$611		$575		$564		$611		$575		$564
Operating income	326		307		307		325		308		308
Net income	234		218		226		239		226		221
As of December 31:
Current assets	67		62				66		61
Non-current assets	3,321		3,100				3,292		3,071
Current liabilities	252		299				252		299
Non-current liabilities	1,652		1,490				1,651		1,487

Cash Surrender Value of Life Insurance Policies

At December 31, the cash surrender value of these investments was as follows (in millions):

	Alliant Energy		IPL		WPL
	2012	2011	2012	2011	2012	2011
Cash surrender value	$50.5	$49.2	$16.0	$15.1	$12.1	$11.9

IPL [Member]

Investment [Line Items]

Cash Surrender Value of Life Insurance Policies

At December 31, the cash surrender value of these investments was as follows (in millions):

	Alliant Energy		IPL		WPL
	2012	2011	2012	2011	2012	2011
Cash surrender value	$50.5	$49.2	$16.0	$15.1	$12.1	$11.9

WPL [Member]

Investment [Line Items]

Unconsolidated Equity Investments

Alliant Energy’s and WPL’s unconsolidated investments accounted for under the equity method of accounting are as follows (in millions):

	Ownership	Carrying Value at
	Interest at	December 31,				Equity (Income) / Loss
	December 31, 2012	2012		2011		2012			2011			2010
Alliant Energy
ATC (a)	16%		$257.0		$238.8		($41.3	)		($37.8	)		($36.9	)
Wisconsin River Power Company	50%	7.3		7.7		(0.8		)	(0.9		)	(0.9		)
Other	Various	2.3		3.1		0.8			(0.6		)	(0.3		)
			$266.6		$249.6		($41.3	)		($39.3	)		($38.1	)
WPL
ATC (a)	16%		$257.0		$238.8		($41.3	)		($37.8	)		($36.9	)
Wisconsin River Power Company	50%	7.3		7.7		(0.8		)	(0.9		)	(0.9		)
			$264.3		$246.5		($42.1	)		($38.7	)		($37.8	)

(a) Alliant Energy and WPL have the ability to exercise significant influence over ATC’s financial and operating policies through their participation on ATC’s Board of Directors. Refer to Note 19 for information regarding related party transactions with ATC.

Summary Financial Information

Summary aggregate financial information from the financial statements of these investments is as follows (in millions):

	Alliant Energy						WPL
	2012		2011		2010		2012		2011		2010
Operating revenues		$611		$575		$564		$611		$575		$564
Operating income	326		307		307		325		308		308
Net income	234		218		226		239		226		221
As of December 31:
Current assets	67		62				66		61
Non-current assets	3,321		3,100				3,292		3,071
Current liabilities	252		299				252		299
Non-current liabilities	1,652		1,490				1,651		1,487

Cash Surrender Value of Life Insurance Policies

At December 31, the cash surrender value of these investments was as follows (in millions):

	Alliant Energy		IPL		WPL
	2012	2011	2012	2011	2012	2011
Cash surrender value	$50.5	$49.2	$16.0	$15.1	$12.1	$11.9