Derivative Instruments (Tables)

9 Months Ended

Sep. 30, 2012

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Notional Amounts Of Derivative Instruments

As of September 30, 2012, notional amounts by delivery year related to outstanding swap contracts, option contracts, physical forward contracts, FTRs and coal contracts that were accounted for as commodity derivative instruments were as follows (units in thousands):

	2012	2013	2014	2015	Total
Alliant Energy
Electricity (megawatt-hours (MWhs))	1,280	3,860	2,118	876	8,134
FTRs (MWs)	16	28	—	—	44
Natural gas (dekatherms (Dths))	26,070	44,899	6,410	—	77,379
Coal (tons)	—	956	981	561	2,498
IPL
Electricity (MWhs)	786	1,978	366	—	3,130
FTRs (MWs)	8	15	—	—	23
Natural gas (Dths)	19,274	32,309	3,235	—	54,818
WPL
Electricity (MWhs)	494	1,882	1,752	876	5,004
FTRs (MWs)	8	13	—	—	21
Natural gas (Dths)	6,796	12,590	3,175	—	22,561
Coal (tons)	—	956	981	561	2,498

Fair Value Of Financial Instruments

The fair values of current derivative assets were included in “Derivative assets,” non-current derivative assets were included in “Deferred charges and other,” current derivative liabilities were included in “Derivative liabilities” and non-current derivative liabilities were included in “Other long-term liabilities and deferred credits” on the Condensed Consolidated Balance Sheets as follows (in millions):

	Alliant Energy				IPL				WPL
	September 30, 2012		December 31, 2011		September 30, 2012		December 31, 2011		September 30, 2012		December 31, 2011
Commodity contracts
Current derivative assets		$35.9		$12.7		$25.9		$9.2		$10.0		$3.5
Non-current derivative assets	10.6		3.0		2.2		1.4		8.4		1.6
Current derivative liabilities	37.8		55.9		17.9		24.5		19.9		31.4
Non-current derivative liabilities	19.5		22.1		4.9		9.1		14.6		13.0

Gains And Losses From Derivative Instruments Not Designated As Hedging Instruments

Gains (losses) from commodity derivative instruments not designated as hedging instruments were recorded on the Condensed Consolidated Balance Sheets as follows (in millions):

	Alliant Energy						IPL						WPL
	2012			2011			2012			2011			2012			2011
Three Months Ended September 30
Regulatory assets		($6.3	)		($23.8	)		($0.1	)		($13.3	)		($6.2	)		($10.5	)
Regulatory liabilities	15.8			3.7			6.9			2.2			8.9			1.5
Nine Months Ended September 30
Regulatory assets	(38.3		)	(33.1		)	(17.3		)	(18.7		)	(21.0		)	(14.4		)
Regulatory liabilities	21.3			8.6			11.3			5.4			10.0			3.2