(9) FAIR VALUE MEASUREMENTS

Fair Value of Financial Instruments—The carrying amounts of Alliant Energy's, IPL's and WPL's current assets and current liabilities approximate fair value because of the short maturity of such financial instruments. Carrying amounts and the related estimated fair values of other financial instruments at Sep. 30, 2011 and Dec. 31, 2010 were as follows (in millions):


	Alliant Energy				IPL				WPL
	Carrying Amount		Fair Value		Carrying Amount		Fair Value		Carrying Amount		Fair Value
Sep. 30, 2011
Assets:
Money market fund investments	$	18.2	$	18.2	$	—	$	—	$	18.2	$	18.2
Derivative assets (Note 10)		25.1		25.1		16.7		16.7		8.0		8.0
Deferred proceeds (sales of receivables) (Note 3)		87.4		87.4		87.4		87.4		—		—
Available-for-sale securities		1.8		1.8		1.8		1.8		—		—
Capitalization and liabilities:
Long-term debt (including current maturities)		2,705.0		3,315.1		1,308.9		1,563.7		1,082.1		1,421.3
Cumulative preferred stock of subsidiaries (Note 6(b))		205.1		222.8		145.1		166.5		60.0		56.3
Derivative liabilities (Note 10)		52.4		52.4		20.7		20.7		31.7		31.7

Dec. 31, 2010
Assets:
Money market fund investments		128.3		128.3		5.6		5.6		—		—
Derivative assets (Note 10)		20.9		20.9		12.9		12.9		8.0		8.0
Deferred proceeds (sales of receivables) (Note 3)		152.9		152.9		152.9		152.9		—		—
Available-for-sale securities		2.1		2.1		2.1		2.1		—		—
Capitalization and liabilities:
Long-term debt (including current maturities)		2,704.7		2,958.6		1,308.6		1,417.0		1,081.7		1,219.6
Cumulative preferred stock of subsidiaries (Note 6(b))		243.8		266.7		183.8		210.7		60.0		56.0
Derivative liabilities (Note 10)		67.3		67.3		24.0		24.0		43.3		43.3

Valuation Techniques—

Money market fund investments—Money market fund investments are measured at fair value each reporting date using quoted market prices on listed exchanges.

Derivative assets and derivative liabilities—As of Sep. 30, 2011 and Dec. 31, 2010, derivative assets and derivative liabilities included swap contracts, option contracts, and physical forward purchase and sale contracts for electricity and natural gas, financial transmission rights (FTRs) and embedded foreign currency derivatives. IPL's and WPL's swap, option and physical forward commodity contracts were non-exchange-based derivative instruments valued using indicative price quotations available through a pricing vendor that provides daily exchange forward price settlements, from broker or dealer quotations or from on-line exchanges. The indicative price quotations reflected the average of the bid-ask mid-point prices and were obtained from sources believed to provide the most liquid market for the commodity. IPL and WPL corroborated a portion of these indicative price quotations using quoted prices for similar assets or liabilities in active markets and categorized derivative instruments based on such indicative price quotations as Level 2. IPL's and WPL's commodity contracts that were valued using indicative price quotations based on significant assumptions such as seasonal or monthly shaping and indicative price quotations that could not be readily corroborated were categorized as Level 3. IPL's and WPL's swap, option and physical forward commodity contracts were predominately at liquid trading points. IPL's and WPL's FTRs were measured at fair value each reporting date using monthly or annual auction shadow prices from relevant auctions. The embedded foreign currency derivatives related to Euro-denominated payment terms included in the wind turbine supply contract with Vestas were measured at fair value using an extrapolation of forward currency rates. Refer to Note 10 for additional details of derivative assets and derivative liabilities.

Deferred proceeds (sales of receivables)—The fair value of IPL's deferred proceeds related to its sales of accounts receivable program was calculated each reporting date using the carrying amount of receivables sold less the allowance for doubtful accounts associated with the receivables sold and cash proceeds received from the receivables sold. Refer to Note 3 for additional information regarding deferred proceeds.

Available-for-sale securities—The fair value of certain IPL investments in various debt and equity securities was measured at fair value each reporting date using quoted market prices on listed exchanges.

Long-term debt (including current maturities)—For long-term debt instruments that are actively traded, the fair value was based upon quoted market prices each reporting date. For long-term debt instruments that are not actively traded, the fair value was based on discounted cash flow methodology and utilizes assumptions of current market pricing curves.

Cumulative preferred stock of subsidiaries—The fair value of IPL's 8.375% cumulative preferred stock was based on its closing market price quoted by the New York Stock Exchange on each reporting date. At Dec. 31, 2010, the fair value of IPL's 7.10% cumulative preferred stock was based on its closing market price quoted by the New York Stock Exchange on that date. The fair value of WPL's 4.50% cumulative preferred stock was based on the closing market price quoted by the NYSE Amex LLC on each reporting date. The fair value of WPL's remaining preferred stock was calculated based on the market yield of similar securities. Refer to Note 6(b) for additional information regarding cumulative preferred stock of subsidiaries, including the April 2011 redemption of IPL's 7.10% cumulative preferred stock.

Valuation Hierarchy—Fair value measurement accounting establishes a fair value hierarchy that prioritizes the inputs to valuation techniques used to measure fair value. The three levels of the fair value hierarchy and examples of each are as follows:

Level 1—Pricing inputs are quoted prices available in active markets for identical assets or liabilities as of the reporting date. Level 1 assets as of Sep. 30, 2011 and Dec. 31, 2010 included money market fund investments and certain IPL investments in securities valued using quoted market prices on listed exchanges.

Level 2—Pricing inputs are quoted prices for similar assets or liabilities in active markets or quoted prices for identical or similar assets or liabilities in markets that are not active as of the reporting date. Level 2 assets and liabilities as of Sep. 30, 2011 and Dec. 31, 2010 included IPL's and WPL's non-exchange traded commodity contracts valued using indicative price quotations that are corroborated with quoted prices for similar assets or liabilities in active markets.

Level 3—Pricing inputs are unobservable inputs for assets or liabilities for which little or no market data exist and require significant management judgment or estimation. Level 3 assets and liabilities as of Sep. 30, 2011 and Dec. 31, 2010 included embedded foreign currency derivatives, IPL's deferred proceeds, and IPL's and WPL's FTRs, natural gas option contracts and certain commodity contracts that are valued using indicative price quotations with shaping assumptions.

The fair value hierarchy gives the highest priority to quoted prices in active markets (Level 1) and the lowest priority to unobservable data (Level 3). In some cases, the inputs used to measure fair value might fall in different levels of the fair value hierarchy. The lowest level input that is significant to a fair value measurement in its entirety determines the applicable level in the fair value hierarchy. Assessing the significance of a particular input to the fair value measurement in its entirety requires judgment, considering factors specific to the asset or liability.

Recurring Fair Value Measurements—Disclosure requirements for Alliant Energy's, IPL's and WPL's recurring items subject to fair value measurements at Sep. 30, 2011 and Dec. 31, 2010 were as follows (in millions):


Alliant Energy	Sep. 30, 2011								Dec. 31, 2010
	Fair Value		Level 1		Level 2		Level 3		Fair Value		Level 1		Level 2		Level 3
Assets:
Money market fund investments	$	18.2	$	18.2	$	—	$	—	$	128.3	$	128.3	$	—	$	—
Derivative assets:
Commodity contracts		24.7		—		7.7		17.0		16.1		—		10.0		6.1
Foreign exchange contracts		0.4		—		—		0.4		4.8		—		—		4.8

Total derivative assets		25.1		—		7.7		17.4		20.9		—		10.0		10.9
Deferred proceeds		87.4		—		—		87.4		152.9		—		—		152.9
Available-for-sale securities		1.8		0.8		0.9		0.1		2.1		0.6		1.4		0.1
Liabilities:
Derivative liabilities:
Commodity contracts		52.4		—		47.3		5.1		67.2		—		63.9		3.3
Foreign exchange contracts		—		—		—		—		0.1		—		—		0.1

Total derivative liabilities		52.4		—		47.3		5.1		67.3		—		63.9		3.4


IPL	Sep. 30, 2011								Dec. 31, 2010
	Fair Value		Level 1		Level 2		Level 3		Fair Value		Level 1		Level 2		Level 3
Assets:
Money market fund investments	$	—	$	—	$	—	$	—	$	5.6	$	5.6	$	—	$	—
Derivative assets:
Commodity contracts		16.7		—		2.9		13.8		8.1		—		3.6		4.5
Foreign exchange contracts		—		—		—		—		4.8		—		—		4.8

Total derivative assets		16.7		—		2.9		13.8		12.9		—		3.6		9.3
Deferred proceeds		87.4		—		—		87.4		152.9		—		—		152.9
Available-for-sale securities		1.8		0.8		0.9		0.1		2.1		0.6		1.4		0.1
Liabilities:
Derivative liabilities:
Commodity contracts		20.7		—		19.3		1.4		24.0		—		23.8		0.2

WPL	Sep. 30, 2011								Dec. 31, 2010
	Fair Value		Level 1		Level 2		Level 3		Fair Value		Level 1		Level 2		Level 3
Assets:
Money market fund investments	$	18.2	$	18.2	$	—	$	—	$	—	$	—	$	—	$	—
Derivative assets:
Commodity contracts		8.0		—		4.8		3.2		8.0		—		6.4		1.6
Liabilities:
Derivative liabilities:
Commodity contracts		31.7		—		28.0		3.7		43.2		—		40.1		3.1
Foreign exchange contracts		—		—		—		—		0.1		—		—		0.1

Total derivative liabilities		31.7		—		28.0		3.7		43.3		—		40.1		3.2

Additional information for Alliant Energy's, IPL's and WPL's recurring fair value measurements using significant unobservable inputs (Level 3 inputs) for the three and nine months ended Sep. 30 was as follows (in millions):


Alliant Energy	Derivative Assets and (Liabilities), net
	Commodity Contracts						Foreign Contracts						Deferred Proceeds				Available-for-sale Securities
Three months ended Sep. 30	2011			2010			2011			2010			2011		2010		2011		2010
Beginning balance, July 1	$	18.1		$	10.3		$	2.1		$	7.9		$	66.4	$	68.1	$	0.1	$	0.1
Total losses (realized/unrealized) included in changes in net assets (a)		(0.1	)		(0.4	)		—			—			—		—		—		—
Transfers in and/or out of Level 3 (b)		—			(0.2	)		—			—			—		—		—		—
Settlements (c)		(6.1	)		(3.8	)		(1.7	)		(0.6	)		21.0		46.5		—		—

Ending balance, Sep. 30	$	11.9		$	5.9		$	0.4		$	7.3		$	87.4	$	114.6	$	0.1	$	0.1

The amount of total losses for the period included in changes in net assets attributable to the change in unrealized losses relating to assets and liabilities held at Sep. 30 (a)	($	0.1	)	($	0.4	)	$	—		$	—		$	—	$	—	$	—	$	—


	Derivative Assets and (Liabilities), net
Alliant Energy	Commodity Contracts						Foreign Contracts					Deferred Proceeds					Available-for-sale Securities
Nine months ended Sep. 30	2011			2010			2011			2010		2011			2010		2011		2010
Beginning balance, Jan. 1	$	2.8		$	2.6		$	4.7		$	3.1	$	152.9		$	—	$	0.1	$	0.1
Total gains (realized/unrealized) included in changes in net assets (a)		—			11.6			—			3.8		—			—		—		—
Transfers in and/or out of Level 3 (b)		0.2			(0.1	)		—			—		—			—		—		—
Purchases		21.8			—			—			—		—			—		—		—
Settlements (c)		(12.9	)		(8.2	)		(4.3	)		0.4		(65.5	)		114.6		—		—

Ending balance, Sep. 30	$	11.9		$	5.9		$	0.4		$	7.3	$	87.4		$	114.6	$	0.1	$	0.1

The amount of total gains for the period included in changes in net assets attributable to the change in unrealized gains relating to assets and liabilities held at Sep. 30 (a)	$	—		$	11.6		$	—		$	3.8	$	—		$	—	$	—	$	—


	Derivative Assets and (Liabilities), net
IPL	Commodity Contracts						Foreign Contracts					Deferred Proceeds				Available-for-sale Securities
Three months ended Sep. 30	2011			2010			2011		2010			2011		2010		2011		2010
Beginning balance, July 1	$	17.5		$	9.7		$	—	$	8.4		$	66.4	$	68.1	$	0.1	$	0.1
Total gains (losses) (realized/unrealized) included in changes in net assets (a)		(0.1	)		0.2			—		—			—		—		—		—
Transfers in and/or out of Level 3 (b)		—			0.1			—		—			—		—		—		—
Settlements (c)		(5.0	)		(3.0	)		—		(0.9	)		21.0		46.5		—		—

Ending balance, Sep. 30	$	12.4		$	7.0		$	—	$	7.5		$	87.4	$	114.6	$	0.1	$	0.1

The amount of total gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at Sep. 30 (a)	($	0.1	)	$	0.2		$	—	$	—		$	—	$	—	$	—	$	—


	Derivative Assets and (Liabilities), net
IPL	Commodity Contracts						Foreign Contracts						Deferred Proceeds					Available-for-sale Securities
Nine months ended Sep. 30	2011			2010			2011			2010			2011			2010		2011		2010
Beginning balance, Jan. 1	$	4.3		$	1.4		$	4.8		$	4.6		$	152.9		$	—	$	0.1	$	0.1
Total gains (realized/unrealized) included in changes in net assets (a)		0.4			10.8			—			3.8			—			—		—		—
Transfers in and/or out of Level 3 (b)		—			0.1			—			—			—			—		—		—
Purchases		18.1			—			—			—			—			—		—		—
Sales (d)		—			—			(2.1	)		—			—			—		—		—
Settlements (c)		(10.4	)		(5.3	)		(2.7	)		(0.9	)		(65.5	)		114.6		—		—

Ending balance, Sep. 30	$	12.4		$	7.0		$	—		$	7.5		$	87.4		$	114.6	$	0.1	$	0.1

The amount of total gains for the period included in changes in net assets attributable to the change in unrealized gains relating to assets and liabilities held at Sep. 30 (a)	$	0.4		$	10.8		$	—		$	3.8		$	—		$	—	$	—	$	—


WPL	Derivative Assets and (Liabilities), net
	Commodity Contracts						Foreign Contracts
Three months ended Sep. 30	2011			2010			2011		2010
Beginning balance, July 1	$	0.6		$	0.6		$	—	($	0.5	)
Total losses (realized/unrealized) included in changes in net assets (a)		—			(0.6	)		—		—
Transfers in and/or out of Level 3 (b)		—			(0.3	)		—		—
Settlements		(1.1	)		(0.8	)		—		0.3

Ending balance, Sep. 30	($	0.5	)	($	1.1	)	$	—	($	0.2	)

The amount of total losses for the period included in changes in net assets attributable to the change in unrealized losses relating to assets and liabilities held at Sep. 30 (a)	$	—		($	0.6	)	$	—	$	—



WPL	Derivative Assets and (Liabilities), net
	Commodity Contracts						Foreign Contracts
Nine months ended Sep. 30	2011			2010			2011			2010
Beginning balance, Jan. 1	($	1.5	)	$	1.2		($	0.1	)	($	1.5	)
Total gains (losses) (realized/unrealized) included in changes in net assets (a)		(0.4	)		0.8			—			—
Transfers in and/or out of Level 3 (b)		0.2			(0.2	)		—			—
Purchases		3.7			—			—			—
Settlements		(2.5	)		(2.9	)		0.1			1.3

Ending balance, Sep. 30	($	0.5	)	($	1.1	)	$	—		($	0.2	)

The amount of total gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at Sep. 30 (a)	($	0.4	)	$	0.8		$	—		$	—

(a)	Gains and losses related to derivative assets and liabilities are recorded in "Regulatory assets" and "Regulatory liabilities" on the Condensed Consolidated Balance Sheets.

(b)	Observable market inputs became available for certain commodity contracts previously classified as Level 3. The transfers were valued as of the beginning of the period.

(c)	Settlements related to deferred proceeds are due to the change in the carrying amount of receivables sold less the allowance for doubtful accounts associated with the receivables sold and cash proceeds received from the receivables sold.

(d)	The foreign exchange contract was transferred from IPL to Resources in connection with the sale of wind project assets in the second quarter of 2011.

Fair Value Measurements

(9) FAIR VALUE MEASUREMENTS

Fair Value of Financial Instruments—The carrying amounts of Alliant Energy's, IPL's and WPL's current assets and current liabilities approximate fair value because of the short maturity of such financial instruments. Carrying amounts and the related estimated fair values of other financial instruments at Sep. 30, 2011 and Dec. 31, 2010 were as follows (in millions):


	Alliant Energy				IPL				WPL
	Carrying Amount		Fair Value		Carrying Amount		Fair Value		Carrying Amount		Fair Value
Sep. 30, 2011
Assets:
Money market fund investments	$	18.2	$	18.2	$	—	$	—	$	18.2	$	18.2
Derivative assets (Note 10)		25.1		25.1		16.7		16.7		8.0		8.0
Deferred proceeds (sales of receivables) (Note 3)		87.4		87.4		87.4		87.4		—		—
Available-for-sale securities		1.8		1.8		1.8		1.8		—		—
Capitalization and liabilities:
Long-term debt (including current maturities)		2,705.0		3,315.1		1,308.9		1,563.7		1,082.1		1,421.3
Cumulative preferred stock of subsidiaries (Note 6(b))		205.1		222.8		145.1		166.5		60.0		56.3
Derivative liabilities (Note 10)		52.4		52.4		20.7		20.7		31.7		31.7

Dec. 31, 2010
Assets:
Money market fund investments		128.3		128.3		5.6		5.6		—		—
Derivative assets (Note 10)		20.9		20.9		12.9		12.9		8.0		8.0
Deferred proceeds (sales of receivables) (Note 3)		152.9		152.9		152.9		152.9		—		—
Available-for-sale securities		2.1		2.1		2.1		2.1		—		—
Capitalization and liabilities:
Long-term debt (including current maturities)		2,704.7		2,958.6		1,308.6		1,417.0		1,081.7		1,219.6
Cumulative preferred stock of subsidiaries (Note 6(b))		243.8		266.7		183.8		210.7		60.0		56.0
Derivative liabilities (Note 10)		67.3		67.3		24.0		24.0		43.3		43.3