Derivative Instruments (Tables)

9 Months Ended

Sep. 30, 2011

Derivative Instruments

Notional Amounts Of Derivative Instruments

	2011		2012		2013		2014		Total
Alliant Energy
Commodity:
Electricity (megawatt-hours (MWhs))		820		2,460		658		—		3,938
FTRs (MWs)		15		23		—		—		38
Natural gas (dekatherms (Dths))		25,049		31,914		6,897		450		64,310
IPL
Commodity:
Electricity (MWhs)		299		1,120		254		—		1,673
FTRs (MWs)		9		14		—		—		23
Natural gas (Dths)		17,288		16,479		3,415		225		37,407
WPL
Commodity:
Electricity (MWhs)		521		1,340		404		—		2,265
FTRs (MWs)		6		9		—		—		15
Natural gas (Dths)		7,606		15,435		3,482		225		26,748

Fair Value Of Financial Instruments

	Alliant Energy				IPL				WPL
	Sep. 30,		Dec. 31,		Sep. 30,		Dec. 31,		Sep. 30,		Dec. 31,
	2011		2010		2011		2010		2011		2010
Current derivative assets
Commodity contracts	$	22.3	$	14.3	$	15.5	$	7.8	$	6.8	$	6.5
Foreign exchange contracts		0.4		4.8		—		4.8		—		—
	$	22.7	$	19.1	$	15.5	$	12.6	$	6.8	$	6.5
Non-current derivative assets
Commodity contracts	$	2.4	$	1.8	$	1.2	$	0.3	$	1.2	$	1.5
Current derivative liabilities
Commodity contracts	$	41.3	$	55.2	$	17.3	$	23.0	$	24.0	$	32.2
Foreign exchange contracts		—		0.1		—		—		—		0.1
	$	41.3	$	55.3	$	17.3	$	23.0	$	24.0	$	32.3
Non-current derivative liabilities
Commodity contracts	$	11.1	$	12.0	$	3.4	$	1.0	$	7.7	$	11.0

Gains And Losses From Derivative Instruments Not Designated As Hedging Instruments

		Gains (Losses)
	Location Recorded on Balance Sheets	Alliant Energy						IPL						WPL
		2011			2010			2011			2010			2011			2010
Three months ended Sep. 30
Commodity contracts	Regulatory assets	$	(23.8	)	$	(43.9	)	$	(13.3	)	$	(22.5	)	$	(10.5	)	$	(21.4	)
Commodity contracts	Regulatory liabilities		3.7			4.5			2.2			2.2			1.5			2.3
Nine months ended Sep. 30
Commodity contracts	Regulatory assets		(33.1	)		(83.1	)		(18.7	)		(48.3	)		(14.4	)		(34.8	)
Commodity contracts	Regulatory liabilities		8.6			10.5			5.4			9.5			3.2			1.0
Foreign exchange contracts	Regulatory liabilities		—			3.8			—			3.8			—			—