Investments (Tables)

12 Months Ended

Dec. 31, 2011

Investments [Abstract]

Unconsolidated Equity Investments

	Ownership Interest at Dec. 31, 2011			Carrying Value at Dec. 31,				Equity (Income) / Loss
				2011		2010		2011			2010			2009
Alliant Energy
ATC (a)		16	%	$	238.8	$	227.9	($	37.8	)	($	36.9	)	($	36.1	)
Wisconsin River Power Company		50	%		7.7		8.1		(0.9	)		(0.9	)		(0.9	)
Other		Various			3.1		2.5		(0.6	)		(0.3	)		0.4
				$	249.6	$	238.5	($	39.3	)	($	38.1	)	($	36.6	)
WPL
ATC (a)		16	%	$	238.8	$	227.9	($	37.8	)	($	36.9	)	($	36.1	)
Wisconsin River Power Company		50	%		7.7		8.1		(0.9	)		(0.9	)		(0.9	)
				$	246.5	$	236.0	($	38.7	)	($	37.8	)	($	37.0	)

(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 21 for information regarding related party transactions with ATC.

Summary Financial Information

	Alliant Energy						WPL
	2011		2010		2009		2011		2010		2009
Operating revenues	$	575	$	564	$	529	$	575	$	564	$	529
Operating income		307		307		292		308		308		294
Net income		218		226		218		226		221		215
As of Dec. 31:
Current assets		62		64				61		63
Non-current assets		3,100		2,941				3,071		2,906
Current liabilities		299		429				299		429
Non-current liabilities		1,490		1,266				1,487		1,263

Cash Surrender Value Of Life Insurance Policies

	Alliant Energy				IPL				WPL
	2011		2010		2011		2010		2011		2010
Cash surrender value	$	49.2	$	48.3	$	15.1	$	14.3	$	11.9	$	12.4