Benefit Plans

12 Months Ended

Dec. 31, 2011

Benefit Plans

(6) BENEFIT PLANS

(a) Pension and Other Postretirement Benefits Plans - Alliant Energy, IPL and WPL provide retirement benefits to substantially all of their employees through various qualified and non-qualified non-contributory defined benefit pension plans, and through defined contribution plans (including 401(k) savings plans). Alliant Energy's, IPL's and WPL's qualified and non-qualified non-contributory defined benefit pension plans are currently closed to new hires. Benefits of the non-contributory defined benefit pension plans are based on the plan participant's years of service, age and compensation. Benefits of the defined contribution plans are based on the plan participant's years of service, age, compensation and contributions. Alliant Energy, IPL and WPL also provide certain defined benefit postretirement health care and life benefits to eligible retirees. In general, the retiree health care plans consist of fixed benefit subsidy structures and the retiree life insurance plans are non-contributory.

Assumptions - The assumptions for Alliant Energy's, IPL's and WPL's defined benefit pension and other postretirement benefits plans at the measurement date of Dec. 31 were as follows (Not Applicable (N/A)):

Alliant Energy

	Defined Benefit Pension Plans			Other Postretirement Benefits Plans
	2011	2010	2009	2011	2010	2009
Discount rate for benefit obligations	4.86%	5.56%	5.8%	4.6%	5.25%	5.55%
Discount rate for net periodic cost	5.56%	5.8%	6.15%	5.25%	5.55%	6.15%
Expected rate of return on plan assets	7.9%	8%	8.25%	7%	6.9%	8.25%
Rate of compensation increase	3.5-4.5%	3.5-4.5%	3.5-4.5%	3.5%	3.5%	3.5%
Medical cost trend on covered charges:
Initial trend rate (end of year)	N/A	N/A	N/A	8%	7%	7.5%
Ultimate trend rate	N/A	N/A	N/A	5%	5%	5%
IPL
	Qualified Defined Benefit Pension Plans			Other Postretirement Benefits Plans
	2011	2010	2009	2011	2010	2009
Discount rate for benefit obligations	4.95%	5.7%	5.8%	4.6%	5.25%	5.55%
Discount rate for net periodic cost	5.7%	5.8%	6.15%	5.25%	5.55%	6.15%
Expected rate of return on plan assets	7.9%	8%	8.25%	7.3%	7.1%	8.25%
Rate of compensation increase	3.5%	3.5%	3.5%	3.5%	3.5%	3.5%
Medical cost trend on covered charges:
Initial trend rate (end of year)	N/A	N/A	N/A	8%	7%	7.5%
Ultimate trend rate	N/A	N/A	N/A	5%	5%	5%

WPL

	Qualified Defined Benefit Pension Plans			Other Postretirement Benefits Plans
	2011	2010	2009	2011	2010	2009
Discount rate for benefit obligations	4.95%	5.7%	5.8%	4.6%	5.25%	5.55%
Discount rate for net periodic cost	5.7%	5.8%	6.15%	5.25%	5.55%	6.15%
Expected rate of return on plan assets	7.9%	8%	8.25%	6.3%	6.3%	8.25%
Rate of compensation increase	3.5%	3.5%	3.5%	3.5%	3.5%	3.5%
Medical cost trend on covered charges:
Initial trend rate (end of year)	N/A	N/A	N/A	8%	7%	7.5%
Ultimate trend rate	N/A	N/A	N/A	5%	5%	5%

Expected rate of return on plan assets - The expected rate of return on plan assets is determined by analysis of projected asset class returns based on the target asset class allocations. Alliant Energy uses a portfolio return simulator and also reviews historical returns, survey information and capital market information to support the expected rate of return on plan assets assumption. Refer to "Investment Policy and Strategy for Plan Assets" below for additional information related to Alliant Energy's investment policy and strategy and mix of assets for the pension and other postretirement benefits plans.

Medical cost trend on covered charges - The assumed medical trend rates are critical assumptions in determining the service and interest cost and accumulated postretirement benefit obligation related to postretirement benefits costs. A 1% change in the medical trend rates for 2011, holding all other assumptions constant, would have the following effects (in millions):

	Alliant Energy					IPL					WPL
	1% Increase		1% Decrease			1% Increase		1% Decrease			1% Increase		1% Decrease
Effect on total of service and interest cost components	$	0.5		($0.4	)	$	0.2		($0.2	)	$	0.2		($0.2	)
Effect on postretirement benefit obligation		2.9		(2.8	)		1.3		(1.2	)		1.5		(1.4	)

Net Periodic Benefit Costs - In the "IPL" and "WPL" tables below, the qualified defined benefit pension plans costs represent only those respective costs for bargaining unit employees of IPL and WPL covered under the plans that are sponsored by IPL and WPL, respectively. Also in the "IPL" and "WPL" tables, the other postretirement benefits costs represent costs for all IPL and WPL employees, respectively. The "Directly assigned defined benefit pension plans" tables include amounts directly assigned to each of IPL and WPL related to IPL's and WPL's current and former non-bargaining employees who are participants in Alliant Energy and Corporate Services sponsored qualified and non-qualified defined benefit pension plans. The components of Alliant Energy's, IPL's and WPL's net periodic benefit costs for their sponsored defined benefit pension and other postretirement benefits plans, and defined benefit pension plans amounts directly assigned to IPL and WPL,as recognized on Alliant Energy's, IPL's and WPL's Consolidated Statements of Income, were as follows (in millions):

Alliant Energy

	Defined Benefit Pension Plans									Other Postretirement Benefits Plans (a)
	2011			2010			2009			2011			2010			2009
Service cost	$	11.4		$	11.9		$	11.9		$	7.0		$	9.3		$	8.7
Interest cost		52.0			52.3			54.3			12.3			14.9			15.2
Expected return on plan assets (b)		(63.8	)		(62.1	)		(47.6	)		(7.9	)		(7.7	)		(6.1	)
Amortization of (c):
Transition obligation		—			—			—			—			0.1			0.2
Prior service cost (credit)		0.7			0.9			2.1			(10.0	)		(2.4	)		(3.7	)
Actuarial loss		21.1			23.8			30.6			5.3			7.4			6.2
Additional benefit costs (d)		10.2			—			—			—			—			—
Settlement losses (e)		1.1			1.4			—			—			—			—
Curtailment losses (f)(g)		—			—			1.0			—			—			—
Special termination benefits costs (g)		—			—			0.9			—			—			—
	$	32.7		$	28.2		$	53.2		$	6.7		$	21.6		$	20.5

IPL

	Qualified Defined Benefit Pension Plans									Other Postretirement Benefits Plans (a)
	2011			2010			2009			2011			2010			2009
Service cost	$	6.1		$	6.2		$	6.1		$	2.6		$	3.4		$	3.1
Interest cost		16.7			16.5			16.1			5.5			6.8			7.3
Expected return on plan assets (b)		(20.0	)		(19.5	)		(14.0	)		(5.4	)		(5.3	)		(4.2	)
Amortization of (c):
Transition obligation		—			—			—			—			0.1			0.2
Prior service cost (credit)		0.5			0.6			0.8			(5.0	)		(1.1	)		(1.6	)
Actuarial loss		5.7			7.2			9.3			2.9			4.0			4.0
	$	9.0		$	11.0		$	18.3		$	0.6		$	7.9		$	8.8
WPL
	Qualified Defined Benefit Pension Plan									Other Postretirement Benefits Plans (a)
	2011			2010			2009			2011			2010			2009
Service cost	$	4.5		$	4.9		$	4.9		$	2.9		$	3.6		$	3.4
Interest cost		16.1			15.7			15.5			4.9			5.5			5.5
Expected return on plan assets (b)		(20.0	)		(19.1	)		(14.1	)		(1.3	)		(1.3	)		(1.1	)
Amortization of (c):
Prior service cost (credit)		0.5			0.5			0.5			(3.4	)		(0.7	)		(0.9	)
Actuarial loss		7.1			8.5			10.4			2.1			2.5			1.3
Curtailment loss (f)		—			—			0.7			—			—			—
Special termination benefits costs (g)		—			—			0.9			—			—			—
	$	8.2		$	10.5		$	18.8		$	5.2		$	9.6		$	8.2
Directly assigned defined benefit pension plans	IPL									WPL
	2011			2010			2009			2011			2010			2009
Interest cost	$	7.3		$	7.8		$	8.7		$	5.5		$	5.6		$	6.1
Expected return on plan assets (b)		(9.7	)		(9.7	)		(8.4	)		(7.3	)		(7.3	)		(6.3	)
Amortization of (c):
Prior service credit		(0.2	)		(0.3	)		(0.1	)		(0.2	)		(0.2	)		—
Actuarial loss		3.0			2.9			4.2			3.0			2.8			3.6
Additional benefit costs (d)		2.8			—			—			0.7			—			—
Curtailment gain		—			—			(0.1	)		—			—			—
	$	3.2		$	0.7		$	4.3		$	1.7		$	0.9		$	3.4

(a) In May 2011, Alliant Energy, IPL and WPL amended their defined benefit postretirement health care plans resulting in a revision to the method and level of coverage provided for participants more than 65 years of age. This amendment was determined to be a significant event, which required Alliant Energy, IPL and WPL to remeasure their defined benefit postretirement health care plans in May 2011. The amendment resulted in a decrease in Alliant Energy's, IPL's and WPL's postretirement benefit obligations of $55 million, $30 million and $16 million, respectively, in 2011 with the impact of the remeasurement on net periodic benefit costs being recognized prospectively from the remeasurement date. The impact of the remeasurement decreased Alliant Energy's, IPL's and WPL's net periodic benefit costs by $11.3 million, $7.2 million, and $3.8 million in 2011, respectively. The discount rate used for the remeasurement was 5.20%. All other assumptions used for the remeasurement were consistent with the measurement assumptions used at Dec. 31, 2010.

(b) The expected return on plan assets is based on the expected rate of return on plan assets and the fair value approach to the market-related value of plan assets.

(c) Unrecognized net actuarial gains or losses in excess of 10% of the greater of the plans' benefit obligation or asset are amortized over the average future service lives of plan participants, except for the Alliant Energy Cash Balance Pension Plan (Cash Balance Plan) where gains or losses outside the 10% threshold are amortized over the time period the participants are expected to receive benefits. Unrecognized prior service costs (credits) for the postretirement benefits plans are amortized over the average future service period to full eligibility of the participants of each plan.

(d) Alliant Energy reached an agreement with the IRS, which resulted in a favorable determination letter for the Cash Balance Plan in 2011. The agreement with the IRS required Alliant Energy to amend the Cash Balance Plan, which was completed in 2011 resulting in aggregate additional benefits of $10.2 million paid to certain former participants in the Cash Balance Plan in 2011. Alliant Energy recognized $10.2 million ($6.3 million at IPL ($2.8 million directly assigned and $3.5 million allocated by Corporate Services) and $3.4 million at WPL ($0.7 million directly assigned and $2.7 million allocated by Corporate Services)) of additional benefits costs in 2011 related to these benefits. Refer to Note 13(b) for additional information regarding the Cash Balance Plan.

(e) In 2011 and 2010, the settlement losses of $1.1 million and $1.4 million, respectively, related to payments made to retired executives of Alliant Energy.

(f) In 2007, members of the International Brotherhood of Electrical Workers Local 965 ratified a four-year collective bargaining agreement reached with WPL, resulting in changes to WPL's qualified pension plan. One of these changes provided WPL qualified pension plan participants an option to cease participating in the WPL qualified pension plan and begin participating in the Alliant Energy 401(k) Savings Plan with increased levels of contribution by Alliant Energy. The election of this option did not impact a participant's eligibility for benefits previously vested under the WPL qualified pension plan. In 2009, certain of these employees elected to cease participating in the WPL qualified pension plan, resulting in Alliant Energy and WPL recognizing a curtailment loss related to the WPL qualified pension plan of $0.7 million in 2009.

(g) In 2009, Alliant Energy eliminated certain corporate and operations positions. As a result, Alliant Energy recognized curtailment losses related to its pension plans of $0.3 million in 2009. In addition, Alliant Energy and WPL recognized special termination benefits costs related to the qualified defined benefit pension plan that is sponsored by WPL of $0.9 million in 2009.

Corporate Services provides services to IPL and WPL, and as a result, IPL and WPL are allocated pension and other postretirement benefits costs associated with Corporate Services employees. The following table includes the allocated qualified and non-qualified pension and other postretirement benefits costs associated with Corporate Services employees providing services to IPL and WPL (in millions):

	Pension Benefits Costs (a)						Other Postretirement Benefits Costs
	2011		2010		2009		2011		2010		2009
IPL	$	5.8	$	2.9	$	5.1	$	0.3	$	2.0	$	1.8
WPL		4.2		1.9		3.2		0.2		1.3		1.2

(a) In 2011, additional qualified pension benefits costs resulting from the 2011 amendment to the Cash Balance Plan allocated to IPL and WPL by Corporate Services were $3.5 million and $2.7 million, respectively.

The estimated amortization from "Regulatory assets" and "Regulatory liabilities" on the Consolidated Balance Sheets and "Accumulated other comprehensive loss" (AOCL) on Alliant Energy's Consolidated Balance Sheet into net periodic benefit cost in 2012 is as follows (in millions):

	Alliant Energy					IPL					WPL
	Defined Benefit Pension Plans		Other Postretirement Benefits Plans			Qualified Defined Benefit Pension Plans		Other Postretirement Benefits Plans			Qualified Defined Benefit Pension Plans		Other Postretirement Benefits Plans
Actuarial loss	$	33.2	$	6.3		$	10.2	$	3.6		$	12.1	$	2.3
Prior service cost (credit)		0.3		(12.0	)		0.4		(6.3	)		0.5		(3.9	)
	$	33.5		($5.7	)	$	10.6		($2.7	)	$	12.6		($1.6	)

Directly assigned defined benefit pension plans	IPL			WPL
Actuarial loss	$	3.9		$	3.6
Prior service credit		(0.2	)		(0.1	)
	$	3.7		$	3.5

In addition to the estimated amortizations from "Regulatory assets" in the above tables for IPL and WPL, $1.9 million and $1.2 million, respectively, of amortizations are expected in 2012 from "Regulatory assets" associated with Corporate Services employees participating in other Alliant Energy sponsored plans allocated to IPL and WPL.

Alliant Energy's, IPL's and WPL's net periodic benefit costs are primarily included in "Utility - other operation and maintenance" in the Consolidated Statements of Income.

Benefit Plan Assets and Obligations - A reconciliation of the funded status of Alliant Energy's qualified and non-qualified defined benefit pension and other postretirement benefits plans to the amounts recognized on Alliant Energy's Consolidated Balance Sheets at Dec. 31 was as follows (in millions):

Alliant Energy

	Defined Benefit Pension Plans						Other Postretirement Benefits Plans
	2011			2010			2011			2010
Change in projected benefit obligation:
Net projected benefit obligation at Jan. 1	$	953.0		$	920.1		$	274.9		$	268.4
Service cost		11.4			11.9			7.0			9.3
Interest cost		52.0			52.3			12.3			14.9
Plan participants' contributions		—			—			6.4			5.6
Plan amendments (a)		10.2			—			(56.6	)		(3.1	)
Actuarial (gain) loss		126.2			27.0			(0.8	)		(0.2	)
Early Retiree Reinsurance Program (ERRP) proceeds		—			—			0.6			—
Gross benefits paid		(71.4	)		(58.3	)		(20.8	)		(21.2	)
Federal subsidy on other postretirement benefits paid		—			—			1.2			1.2
Net projected benefit obligation at Dec. 31		1,081.4			953.0			224.2			274.9
Change in plan assets:
Fair value of plan assets at Jan. 1		823.0			776.4			122.7			102.4
Actual return on plan assets		28.9			96.9			2.6			14.0
Employer contributions		116.9			8.0			9.5			21.9
Plan participants' contributions		—			—			6.4			5.6
Gross benefits paid		(71.4	)		(58.3	)		(20.8	)		(21.2	)
Fair value of plan assets at Dec. 31		897.4			823.0			120.4			122.7
Under funded status at Dec. 31		($184.0	)		($130.0	)		($103.8	)		($152.2	)
Amounts recognized on the Consolidated Balance Sheets consist of:
Non-current assets	$	—		$	—		$	1.3		$	—
Other current liabilities		(4.6	)		(6.9	)		—			—
Pension and other benefit obligations		(179.4	)		(123.1	)		(105.1	)		(152.2	)
Net amount recognized at Dec. 31		($184.0	)		($130.0	)		($103.8	)		($152.2	)

Amounts recognized in Regulatory Assets, Regulatory Liabilities and AOCL consist of (b):
Net actuarial loss	$	494.8		$	356.0		$	76.7		$	77.1
Prior service credit		(6.9	)		(6.2	)		(52.5	)		(5.7	)
	$	487.9		$	349.8		$	24.2		$	71.4

(a) Refer to "Net Periodic Benefit Costs" above for additional information regarding plan amendments to the defined benefit pension and other postretirement benefits plans in 2011.

(b) Refer to Note 1(b) and Alliant Energy's Consolidated Statements of Common Equity for amounts recognized in "Regulatory assets" and "AOCL," respectively, on Alliant Energy's Consolidated Balance Sheets. At Dec. 31, 2011, $3.3 million of regulatory liabilities were recognized related to Alliant Energy's other postretirement benefits plans.

 A reconciliation of the funded status of IPL's and WPL's sponsored qualified defined benefit pension and

other postretirement benefits plans to the amounts recognized on IPL's and WPL's Consolidated Balance Sheets, at Dec. 31 was as follows (in millions):

IPL

	Qualified Defined Benefit Pension Plans						Other Postretirement Benefits Plans
	2011			2010			2011			2010
Change in projected benefit obligation:
Net projected benefit obligation at Jan. 1	$	293.8		$	284.3		$	128.5		$	123.9
Service cost		6.1			6.2			2.6			3.4
Interest cost		16.7			16.5			5.5			6.8
Plan participants' contributions		—			—			2.0			1.6
Plan amendments (a)		—			—			(30.1	)		(1.7	)
Actuarial (gain) loss		45.2			3.1			(2.7	)		4.0
ERRP proceeds		—			—			0.2			—
Gross benefits paid		(17.3	)		(16.3	)		(9.1	)		(10.1	)
Federal subsidy on other postretirement benefits paid		—			—			0.6			0.6
Net projected benefit obligation at Dec. 31		344.5			293.8			97.5			128.5
Change in plan assets:
Fair value of plan assets at Jan. 1		256.9			242.8			77.5			68.4
Actual return on plan assets		9.1			30.4			1.4			9.6
Employer contributions		50.0			—			2.9			8.0
Plan participants' contributions		—			—			2.0			1.6
Gross benefits paid		(17.3	)		(16.3	)		(9.1	)		(10.1	)
Fair value of plan assets at Dec. 31		298.7			256.9			74.7			77.5
Under funded status at Dec. 31		($45.8	)		($36.9	)		($22.8	)		($51.0	)
Amounts recognized on the Consolidated Balance Sheets consist of:

Pension and other benefit obligations		($45.8	)		($36.9	)		($22.8	)		($51.0	)
Amounts recognized in Regulatory Assets and Regulatory Liabilities consist of (b):
Net actuarial loss	$	141.1		$	90.8		$	41.0		$	42.4
Prior service cost (credit)		1.1			1.6			(27.6	)		(2.5	)
	$	142.2		$	92.4		$	13.4		$	39.9

WPL

	Qualified Defined Benefit Pension Plan						Other Postretirement Benefits Plans
	2011			2010			2011			2010
Change in projected benefit obligation:
Net projected benefit obligation at Jan. 1	$	283.3		$	271.6		$	103.3		$	99.1
Service cost		4.5			4.9			2.9			3.6
Interest cost		16.1			15.7			4.9			5.5
Plan participants' contributions		—			—			3.3			3.2
Plan amendments (a)		—			—			(18.2	)		(1.5	)
Actuarial loss		43.3			2.5			2.3			1.9
ERRP proceeds		—			—			0.2			—
Gross benefits paid		(14.7	)		(11.4	)		(9.6	)		(9.0	)
Federal subsidy on other postretirement benefits paid		—			—			0.5			0.5
Net projected benefit obligation at Dec. 31		332.5			283.3			89.6			103.3
Change in plan assets:
Fair value of plan assets at Jan. 1		255.2			236.6			25.0			18.8
Actual return on plan assets		9.1			30.0			0.9			2.1
Employer contributions		40.0			—			5.5			9.9
Plan participants' contributions		—			—			3.3			3.2
Gross benefits paid		(14.7	)		(11.4	)		(9.6	)		(9.0	)
Fair value of plan assets at Dec. 31		289.6			255.2			25.1			25.0
Under funded status at Dec. 31		($42.9	)		($28.1	)		($64.5	)		($78.3	)

WPL

	Qualified Defined Benefit Pension Plan						Other Postretirement Benefits Plans
	2011			2010			2011			2010
Amounts recognized on the Consolidated Balance Sheets consist of:
Non-current asset	$	—		$	—		$	1.3		$	—
Pension and other benefit obligations		(42.9	)		(28.1	)		(65.8	)		(78.3	)
Net amount recognized at Dec. 31		($42.9	)		($28.1	)		($64.5	)		($78.3	)
Amounts recognized in Regulatory Assets:
Net actuarial loss	$	142.7		$	95.6		$	27.8		$	27.2
Prior service cost (credit)		2.4			2.9			(17.3	)		(2.5	)
	$	145.1		$	98.5		$	10.5		$	24.7

(a) Refer to "Net Periodic Benefit Costs" above for additional information regarding plan amendments to the defined benefit pension and other postretirement benefits plans in 2011.

(b) At Dec. 31, 2011, $2.8 million of regulatory liabilities were recognized related to IPL's other postretirement benefits plans.

Included in the following tables are Alliant Energy's, IPL's and WPL's accumulated benefit obligations, aggregate amounts applicable to defined benefit pension and other postretirement benefits plans with accumulated benefit obligations in excess of plan assets, as well as defined benefit pension plans with projected benefit obligations in excess of plan assets as of the Dec. 31 measurement date (Not Applicable (N/A); in millions):

Alliant Energy

	Defined Benefit Pension Plans				Other Postretirement Benefits Plans
	2011		2010		2011		2010
Accumulated benefit obligations	$	1,029.4	$	915.5	$	224.2	$	274.9
Plans with accumulated benefit obligations in excess of plan assets:
Accumulated benefit obligations		1,029.4		915.5		224.2		274.9
Fair value of plan assets		897.4		823.0		120.4		122.7
Plans with projected benefit obligations in excess of plan assets:
Projected benefit obligations		1,081.4		953.0		N/A		N/A
Fair value of plan assets		897.4		823.0		N/A		N/A

IPL

	Qualified Defined Benefit Pension Plans				Other Postretirement Benefits Plans
	2011		2010		2011		2010
Accumulated benefit obligations	$	314.6	$	274.1	$	97.5	$	128.5
Plans with accumulated benefit obligations in excess of plan assets:
Accumulated benefit obligations		314.6		274.1		97.5		128.5
Fair value of plan assets		298.7		256.9		74.7		77.5
Plans with projected benefit obligations in excess of plan assets:
Projected benefit obligations		344.5		293.8		N/A		N/A
Fair value of plan assets		298.7		256.9		N/A		N/A

WPL

	Qualified Defined Benefit Pension Plans				Other Postretirement Benefits Plans
	2011		2010		2011		2010
Accumulated benefit obligations	$	314.7	$	270.2	$	89.6	$	103.3
Plans with accumulated benefit obligations in excess of plan assets:
Accumulated benefit obligations		314.7		270.2		89.6		103.3
Fair value of plan assets		289.6		255.2		25.1		25.0
Plans with projected benefit obligations in excess of plan assets:
Projected benefit obligations		332.5		283.3		N/A		N/A
Fair value of plan assets		289.6		255.2		N/A		N/A

The "Directly assigned defined benefit pension plans" table below includes amounts directly assigned to each of IPL and WPL related to IPL's and WPL's current and former non-bargaining employees who are participants in Alliant Energy and Corporate Services sponsored qualified and non-qualified defined benefit pension plans. A reconciliation of the funded status of the directly assigned qualified and non-qualified defined benefit pension plans to the amounts recognized on IPL's and WPL's Consolidated Balance Sheets at Dec. 31 was as follows (in millions):

Directly assigned defined benefit pension plans

	IPL						WPL
	2011			2010			2011			2010
Change in projected benefit obligation:
Net projected benefit obligation at Jan. 1	$	144.4		$	138.8		$	107.4		$	100.9
Interest cost		7.3			7.8			5.5			5.6
Plan amendments		2.8			—			0.7			—
Actuarial loss		13.2			8.0			10.3			8.7
Gross benefits paid		(12.3	)		(10.2	)		(8.7	)		(7.8	)
Net projected benefit obligation at Dec. 31		155.4			144.4			115.2			107.4
Change in plan assets:
Fair value of plan assets at Jan. 1		127.6			121.6			95.6			92.0
Actual return on plan assets		4.2			15.1			3.2			11.2
Employer contributions		7.9			1.1			6.9			0.2
Gross benefits paid		(12.3	)		(10.2	)		(8.7	)		(7.8	)
Fair value of plan assets at Dec. 31		127.4			127.6			97.0			95.6
Under funded status at Dec. 31		($28.0	)		($16.8	)		($18.2	)		($11.8	)
Amounts recognized on the Consolidated Balance Sheets consist of:
Other current liabilities		($0.8	)		($1.0	)		($0.2	)		($0.1	)
Pension and other benefit obligations		(27.2	)		(15.8	)		(18.0	)		(11.7	)
Net amount recognized at Dec. 31		($28.0	)		($16.8	)		($18.2	)		($11.8	)
Amounts recognized in Regulatory Assets:
Net actuarial loss	$	76.2		$	60.5		$	73.7		$	62.3
Prior service credit		(3.4	)		(3.6	)		(2.4	)		(2.6	)
	$	72.8		$	56.9		$	71.3		$	59.7
Accumulated benefit obligations	$	155.4		$	144.4		$	115.2		$	107.4

In addition to the amounts recognized in "Regulatory assets and regulatory liabilities" in the above tables for IPL and WPL, "Regulatory assets" and "Regulatory liabilities" were recognized for amounts associated with Corporate Services employees participating in other Alliant Energy sponsored benefit plans that were allocated to IPL and WPL at Dec. 31 as follows (in millions):

	IPL				WPL
	2011		2010		2011		2010
Regulatory assets	$	33.7	$	28.2	$	22.3	$	18.6
Regulatory liabilities		0.3		—		0.2		—

Estimated Future Employer Contributions and Benefit Payments - Alliant Energy, IPL, and WPL estimate that funding for the qualified defined benefit pension, non-qualified defined benefit pension and other postretirement benefits plans, and the directly assigned qualified and non-qualified defined benefit pension plans amounts, during 2012 will be as follows (in millions):

	Alliant Energy		IPL			WPL
Qualified defined benefit pension plans		$—	$	—		$	—
Non-qualified defined benefit pension plans		17.0			(a)			(a)
Directly assigned defined benefit pension plans (b)		N/A		0.8			0.2
Other postretirement benefits plans		4.9		0.6			3.9

(a) Alliant Energy sponsors several non-qualified defined benefit pension plans that cover certain current and former key employees of IPL and WPL. Alliant Energy allocates pension costs to IPL and WPL for these plans.

(b) Amounts directly assigned to IPL and WPL for non-bargaining employees who are participants in Alliant Energy and Corporate Services sponsored qualified and non-qualified defined benefit pension plans.

Alliant Energy's, IPL's and WPL's expected benefit payments, and the directly assigned qualified and non-qualified defined benefit pension benefits amounts, which reflect expected future service, as appropriate, are as follows (in millions):

Alliant Energy

	2012		2013		2014		2015		2016		2017 - 2021
Qualified and non-qualified defined benefit pension benefits	$	58.8	$	59.1	$	62.3	$	66.3	$	65.2	$	355.4
Other postretirement benefits		18.0		18.1		18.4		17.1		17.3		88.7
	$	76.8	$	77.2	$	80.7	$	83.4	$	82.5	$	444.1
IPL
	2012		2013		2014		2015		2016		2017 - 2021
Qualified defined benefit pension benefits	$	15.5	$	16.2	$	17.1	$	18.2		19.2	$	111.6
Directly assigned defined benefit pension benefits		12.1		11.4		12.3		13.0		11.0		57.0
Other postretirement benefits		8.9		8.7		8.6		7.4		7.4		37.0
	$	36.5	$	36.3	$	38.0	$	38.6	$	37.6	$	205.6
WPL
	2012		2013		2014		2015		2016		2017 - 2021
Qualified defined benefit pension benefits	$	13.0	$	13.8	$	14.9	$	15.9	$	17.0	$	103.3
Directly assigned defined benefit pension benefits		9.0		9.4		9.5		9.5		9.2		40.9
Other postretirement benefits		6.8		7.0		7.2		7.1		7.3		37.4
	$	28.8	$	30.2	$	31.6	$	32.5	$	33.5	$	181.6

Investment Policy and Strategy for Plan Assets - Alliant Energy's, IPL's and WPL's investment strategy and their policies employed with respect to assets of defined benefit pension and other postretirement benefits plans are to combine both preservation of principal and prudent and reasonable risk-taking to protect the integrity of plan assets, in order to meet the obligations to plan participants while minimizing benefit costs over the long term. It is recognized that risk and volatility are present with all types of investments. However, high levels of risk are mitigated at the total fund level through diversification by asset class including both U.S. and international equity exposure, the number of individual investments, and sector and industry limits when applicable. Alliant Energy, IPL and WPL also use an overlay management service to help maintain target allocations, liquidity needs and intended exposures to the plan assets. The overlay manager is authorized to use derivative financial instruments to facilitate this service.

Defined Benefit Pension Plans Assets - For assets of defined benefit pension plans, the mix among asset classes is controlled by long-term asset allocation targets. The assets are viewed as long-term with moderate liquidity needs. Historical performance results and future expectations suggest that equity securities will provide higher total investment returns than debt securities over a long-term investment horizon. Consistent with the goals of meeting obligations to plan participants and minimizing benefit costs over the long-term, the defined benefit pension plans have a long-term investment posture more heavily weighted towards equity holdings. The asset allocation mix is monitored regularly and appropriate steps are taken as needed to rebalance the assets within the prescribed range. Prohibited investment vehicles include, but may not be limited to, direct ownership of real estate, options and futures (unless specifically approved as is the case of the overlay manager), margin trading, oil and gas limited partnerships, commodities, short selling and securities of the managers' firms or affiliate firms. At Dec. 31, 2011, the current target range and actual allocations for Alliant Energy's, IPL's and WPL's defined benefit pension plan assets were as follows:

	Target Range	Actual
	Allocation	Allocation
Cash and equivalents (a)	0%-5%		13	%
Equity securities:
U.S. large cap core	10%-20%		12	%
U.S. large cap value	8%-16%		10	%
U.S. large cap growth	8%-16%		10	%
U.S. small cap value	0%-6%		3	%
U.S. small cap growth	0%-4%		2	%
International - developed markets	12%-24%		14	%
International - emerging markets	0%-8%		4	%
Fixed income securities	20%-40%		32	%

(a) Pension contributions of $100 million were made in late December 2011 and were invested in equity futures.

Other Postretirement Benefits Plans Assets - Other postretirement benefits plans assets are comprised of specific assets within certain defined benefit pension plans (401(h) assets) as well as assets held in Voluntary Employees' Beneficiary Association (VEBA) trusts. The investment policy and strategy of the 401(h) assets mirrors those of the defined benefit pension plans, which are discussed above. A mix of both equity and debt securities are utilized to maximize returns and mitigate risk over the long-term. There are no specific target allocations for the VEBA trusts as a whole. Separate investment guidelines have been established for the VEBA trusts which are actively managed. At Dec. 31, 2011, Alliant Energy's, IPL's and WPL's other postretirement benefits plan assets consisted of the following:

	Alliant Energy			IPL			WPL
Equity securities		58	%		63	%		39	%
Fixed income securities		31	%		34	%		19	%
Cash and equivalents		11	%		3	%		42	%

Securities Lending Program - Alliant Energy, IPL and WPL have a securities lending program with a third-party agent that allows the agent to lend certain securities from their defined benefit pension and other postretirement benefits plans to selected entities against receipt of collateral (in the form of cash, government and agency securities or letters of credit) as provided for and determined in accordance with its securities lending agency agreement. Initial collateral levels are no less than 100% of the market value of loans to non-affiliated borrowers of U.S. government securities; 102% of the market value of loans to affiliated borrowers of U.S. government securities; 102% of the market value of loans on U.S. corporate bonds and U.S. equity securities; 105% of the market value of loans on non-U.S. securities; and 102% of the market value of loans on all other securities. Refer to "Fair Value Measurements" below for details of Alliant Energy's, IPL's and WPL's fair value of invested collateral and amounts due to borrowers for the securities lending program.

Fair Value Measurements - The following tables report a framework for measuring fair value. The fair value hierarchy 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. Alliant Energy's, IPL's and WPL's investments in equity and fixed income securities held in registered investment companies and directly held equity securities are valued at the closing price reported in the active market in which the securities are traded. Level 1 plan assets also include interest-bearing cash, which is held in money market accounts managed by an affiliate of the trustee and money market funds within their securities lending invested collateral.

Level 2 - Pricing inputs are quoted prices for similar asset or liabilities in active markets, quoted prices for identical or similar assets or liabilities in inactive markets, inputs other than quoted prices that are observable for the asset or liability and inputs that are derived principally from or corroborated by observable market data by correlation or other means. Alliant Energy's, IPL's and WPL's investments in corporate bonds and government and agency obligations are valued at the closing price reported in the active market for similar assets in which the individual securities are traded or based on yields currently available on comparable securities of issuers with similar credit ratings. Alliant Energy's, IPL's and WPL's investments in equity and fixed income securities in common/collective trusts are valued at the net asset value of shares held by the plans, which is based on the fair market value of the underlying investments in equity and fixed income securities of the common/collective trusts. Level 2 plan assets also consist of asset backed securities within their securities lending invested collateral.

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. Alliant Energy's, IPL's and WPL's Level 3 plan assets include certain asset backed securities and corporate bonds within their securities lending invested collateral.

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.

The methods described above may produce a fair value calculation that may not be indicative of net realizable value or reflective of future fair values. Furthermore, while Alliant Energy, IPL and WPL believe their valuation methods are appropriate and consistent with other market participants, the use of different methodologies or assumptions to determine the fair value of certain financial instruments could result in a different fair value measurement at the reporting date.

At Dec. 31, the fair values of Alliant Energy's qualified and non-qualified defined benefit pension plans assets by asset category and fair value hierarchy level were as follows (in millions):

Alliant Energy

	2011									2010
	Fair Value			Level 1		Level 2		Level 3		Fair Value			Level 1		Level 2		Level 3
Cash and equivalents	$	117.5		$	117.5	$	—	$	—	$	11.1		$	11.1	$	—	$	—
Equity securities:
U.S. large cap core		110.7			110.7		—		—		118.4			118.4		—		—
U.S. large cap value		91.6			—		91.6		—		100.4			—		100.4		—
U.S. large cap growth		91.5			—		91.5		—		101.0			—		101.0		—
U.S. small cap value		25.7			—		25.7		—		29.0			—		29.0		—
U.S. small cap growth		21.7			21.7		—		—		16.6			16.6		—		—
International - developed markets		126.4			65.4		61.0		—		142.3			76.0		66.3		—
International - emerging markets		30.4			30.4		—		—		34.1			34.1		—		—
Fixed income securities:
Corporate bonds		57.1			—		57.1		—		54.2			—		54.2		—
Government and agency obligations		87.8			—		87.8		—		78.9			—		78.9		—
Fixed income funds		146.7			0.2		146.5		—		142.7			0.2		142.5		—
Securities lending invested collateral		9.3			4.7		2.8		1.8		17.3			3.0		11.5		2.8
		916.4		$	350.6	$	564.0	$	1.8		846.0		$	259.4	$	583.8	$	2.8
Accrued investment income		1.0									1.2
Due to brokers, net (a)		(4.7	)								(0.6	)
Due to borrowers for securities lending program		(15.3	)								(23.6	)
Total pension plan assets	$	897.4								$	823.0

(a) This category represents pending trades with brokers.

At Dec. 31, the fair values of IPL's and WPL's qualified and non-qualified defined benefit pension plan assets associated with IPL's and WPL's current and former non-bargaining employees who are participants in Alliant Energy and Corporate Services sponsored plans that were directly assigned to IPL and WPL, along with the percentage these assets represent of the fair values by asset category and fair value hierarchy level shown in the above table were as follows (dollars in millions):

	IPL						WPL
	2011			2010			2011			2010
Fair values of directly assigned amounts	$	127.4		$	127.6		$	97.0		$	95.6
Percentage represented		14.2	%		15.5	%		10.8	%		11.6	%

At Dec. 31, the fair values of IPL's and WPL's qualified defined benefit pension plans assets by asset category and fair value hierarchy level were as follows (in millions):

IPL

	2011									2010
	Fair Value			Level 1		Level 2		Level 3		Fair Value			Level 1		Level 2		Level 3
Cash and equivalents	$	39.1		$	39.1	$	—	$	—	$	3.5		$	3.5	$	—	$	—
Equity securities:
U.S. large cap core		36.8			36.8		—		—		37.0			37.0		—		—
U.S. large cap value		30.5			—		30.5		—		31.4			—		31.4		—
U.S. large cap growth		30.5			—		30.5		—		31.5			—		31.5		—
U.S. small cap value		8.6			—		8.6		—		9.0			—		9.0		—
U.S. small cap growth		7.2			7.2		—		—		5.2			5.2		—		—
International - developed markets		42.1			21.8		20.3		—		44.4			23.7		20.7		—
International - emerging markets		10.1			10.1		—		—		10.7			10.7		—		—
Fixed income securities:
Corporate bonds		19.0			—		19.0		—		16.9			—		16.9		—
Government and agency obligations		29.2			—		29.2		—		24.6			—		24.6		—
Fixed income funds		48.8			0.1		48.7		—		44.5			—		44.5		—
Securities lending invested collateral		3.1			1.6		0.9		0.6		5.4			0.9		3.6		0.9
		305.0		$	116.7	$	187.7	$	0.6		264.1		$	81.0	$	182.2	$	0.9
Accrued investment income		0.4									0.4
Due to brokers, net (a)		(1.6	)								(0.2	)
Due to borrowers for securities lending program		(5.1	)								(7.4	)
Total pension plan assets	$	298.7								$	256.9

WPL

	2011									2010
	Fair Value			Level 1		Level 2		Level 3		Fair Value			Level 1		Level 2		Level 3
Cash and equivalents	$	37.9		$	37.9	$	—	$	—	$	3.4		$	3.4	$	—	$	—
Equity securities:
U.S. large cap core		35.7			35.7		—		—		36.7			36.7		—		—
U.S. large cap value		29.6			—		29.6		—		31.2			—		31.2		—
U.S. large cap growth		29.5			—		29.5		—		31.3			—		31.3		—
U.S. small cap value		8.3			—		8.3		—		9.0			—		9.0		—
U.S. small cap growth		7.0			7.0		—		—		5.2			5.2		—		—
International - developed markets		40.8			21.1		19.7		—		44.1			23.6		20.5		—
International - emerging markets		9.8			9.8		—		—		10.6			10.6		—		—
Fixed income securities:
Corporate bonds		18.4			—		18.4		—		16.8			—		16.8		—
Government and agency obligations		28.3			—		28.3		—		24.5			—		24.5		—
Fixed income funds		47.4			0.1		47.3		—		44.2			—		44.2		—
Securities lending invested collateral		3.0			1.5		0.9		0.6		5.4			1.0		3.5		0.9
		295.7		$	113.1	$	182.0	$	0.6		262.4		$	80.5	$	181.0	$	0.9
Accrued investment income		0.3									0.3
Due to brokers, net (a)		(1.5	)								(0.2	)
Due to borrowers for securities lending program		(4.9	)								(7.3	)
Total pension plan assets	$	289.6								$	255.2

(a) This category represents pending trades with brokers.

At Dec. 31, the fair values of Alliant Energy's, IPL's and WPL's other postretirement benefits plans assets by asset category and fair value hierarchy level were as follows (in millions):

Alliant Energy

	2011									2010
	Fair Value			Level 1		Level 2		Level 3		Fair Value			Level 1		Level 2		Level 3
Cash and equivalents	$	14.0		$	14.0	$	—	$	—	$	15.4		$	15.4	$	—	$	—
Equity securities:
U.S. large cap core		37.1			37.1		—		—		38.6			38.6		—		—
U.S. large cap value		2.4			—		2.4		—		2.7			—		2.7		—
U.S. large cap growth		2.4			—		2.4		—		2.7			—		2.7		—
U.S. mid cap core		17.8			17.8		—		—		18.6			18.6		—		—
U.S. small cap core		4.7			4.7		—		—		3.8			3.8		—		—
U.S. small cap value		0.6			—		0.6		—		0.8			—		0.8		—
U.S. small cap growth		0.5			0.5		—		—		0.4			0.4		—		—
International - developed markets		3.3			1.7		1.6		—		3.9			2.1		1.8		—
International - emerging markets		0.8			0.8		—		—		0.9			0.9		—		—
Fixed income securities:
Corporate bonds		6.1			—		6.1		—		6.3			—		6.3		—
Government and agency obligations		5.6			—		5.6		—		4.9			—		4.9		—
Fixed income funds		25.4			21.6		3.8		—		24.0			20.1		3.9		—
Securities lending invested collateral		0.4			0.2		0.1		0.1		0.8			0.2		0.5		0.1
		121.1		$	98.4	$	22.6	$	0.1		123.8		$	100.1	$	23.6	$	0.1
Accrued investment income		0.1									0.1
Due to brokers, net (a)		(0.2	)								(0.1	)
Due to borrowers for securities lending program		(0.6	)								(1.1	)
Total other postretirement benefits plan assets	$	120.4								$	122.7

IPL

	2011									2010
	Fair Value			Level 1		Level 2		Level 3		Fair Value			Level 1		Level 2		Level 3
Cash and equivalents	$	2.1		$	2.1	$	—	$	—	$	3.5		$	3.5	$	—	$	—
Equity securities:
U.S. large cap core		29.3			29.3		—		—		30.7			30.7		—		—
U.S. large cap value		0.8			—		0.8		—		1.0			—		1.0		—
U.S. large cap growth		0.8			—		0.8		—		1.0			—		1.0		—
U.S. mid cap core		14.7			14.7		—		—		15.3			15.3		—		—
U.S. small cap value		0.2			—		0.2		—		0.3			—		0.3		—
U.S. small cap growth		0.2			0.2		—		—		0.2			0.2		—		—
International - developed markets		1.2			0.6		0.6		—		1.4			0.8		0.6		—
International - emerging markets		0.3			0.3		—		—		0.3			0.3		—		—
Fixed income securities:
Corporate bonds		4.6			—		4.6		—		4.5			—		4.5		—
Government and agency obligations		4.1			—		4.1		—		3.3			—		3.3		—
Fixed income funds		16.5			15.1		1.4		—		16.0			14.6		1.4		—
Securities lending invested collateral		0.2			0.1		0.1		—		0.5			0.1		0.3		0.1
		75.0		$	62.4	$	12.6	$	—		78.0		$	65.5	$	12.4	$	0.1
Accrued investment income		0.1									0.2
Due to borrowers for securities lending program		(0.4	)								(0.7	)
Total other postretirement benefits plan assets	$	74.7								$	77.5

WPL

	2011									2010
	Fair Value			Level 1		Level 2		Level 3		Fair Value			Level 1		Level 2		Level 3
Cash and equivalents	$	10.5		$	10.5	$	—	$	—	$	10.7		$	10.7	$	—	$	—
Equity securities:
U.S. large cap core		1.2			1.2		—		—		1.3			1.3		—		—
U.S. large cap value		1.0			—		1.0		—		1.1			—		1.1		—
U.S. large cap growth		1.0			—		1.0		—		1.1			—		1.1		—
U.S. small cap core		4.7			4.7		—		—		3.8			3.8		—		—
U.S. small cap value		0.3			—		0.3		—		0.3			—		0.3		—
U.S. small cap growth		0.2			0.2		—		—		0.2			0.2		—		—
International - developed markets		1.3			0.7		0.6		—		1.6			0.8		0.8		—
International - emerging markets		0.3			0.3		—		—		0.4			0.4		—		—
Fixed income securities:
Corporate bonds		1.1			—		1.1		—		1.4			—		1.4		—
Government and agency obligations		1.0			—		1.0		—		1.0			—		1.0		—
Fixed income funds		2.6			1.0		1.6		—		2.3			0.7		1.6		—
Securities lending invested collateral		0.1			0.1		—		—		0.2			0.1		0.1		—
		25.3		$	18.7	$	6.6	$	—		25.4		$	18.0	$	7.4	$	—
Due to brokers, net (a)		(0.1	)								(0.1	)
Due to borrowers for securities lending program		(0.1	)								(0.3	)
Total other postretirement benefits plan assets	$	25.1								$	25.0

(a) This category represents pending trades with brokers.

For the various Alliant Energy defined benefit pension and other postretirement benefits plans, Alliant Energy common stock represented less than 1% of total plan assets at Dec. 31, 2011 and 2010.

Alliant Energy Cash Balance Plan - Alliant Energy's defined benefit pension plans include the Cash Balance Plan that provides benefits for certain non-bargaining unit employees. The Cash Balance Plan has been closed to new hires since 2005. Effective 2008, Alliant Energy amended the Cash Balance Plan by discontinuing additional contributions into employees' Cash Balance Plan accounts. Also effective 2008, Alliant Energy increased its level of contributions to its 401(k) Savings Plan, which offset the impact of discontinuing additional contributions into the employees' Cash Balance Plan accounts. In 2009, Alliant Energy amended the Cash Balance Plan by changing participants' future interest credit formula to use the annual change in the consumer price index as the interest credit. This amendment provides participants an interest crediting rate that is 3% more than the annual change in the consumer price index. Refer to Note 13(b) for discussion of a class action lawsuit filed against the Cash Balance Plan in 2008 and the IRS review of the tax qualified status of the Plan.

401(k) Savings Plans - A significant number of Alliant Energy, IPL and WPL employees participate in defined contribution retirement plans (401(k) savings plans). The number of employees participating in these plans has increased recently as certain bargaining unit employees have elected to participate in defined contribution retirement plans instead of defined benefit pension plans. In 2009, Alliant Energy, IPL and WPL implemented several cost saving initiatives to reduce operation and maintenance expenses, including suspension of a portion of 401(k) savings plans contributions during the second half of 2009. Alliant Energy common stock represented 14.6% and 12.9% of total assets held in 401(k) savings plans at Dec. 31, 2011 and 2010, respectively. Alliant Energy's, IPL's and WPL's costs related to the 401(k) savings plans, which are partially based on the participants' level of contribution, were as follows (in millions):

	Alliant Energy						IPL						WPL
	2011		2010		2009		2011		2010		2009		2011		2010		2009
401(k) savings plans costs	$	18.7	$	18.5	$	16.2	$	9.2	$	8.8	$	2.8	$	8.4	$	8.9	$	4.3

(b) Equity Incentive Plans - In 2010, Alliant Energy's shareowners approved the Alliant Energy 2010 Omnibus Incentive Plan (OIP), which permits the grant of stock options, restricted stock, restricted stock units, performance shares, performance units, and other stock-based awards and cash incentive awards to key employees. At Dec. 31, 2011, performance shares and restricted stock were outstanding and 4.3 million shares of Alliant Energy's common stock remained available for grants under the OIP. Upon shareowner approval of the OIP, the Alliant Energy 2002 Equity Incentive Plan (EIP) terminated resulting in no new awards authorized to be granted under the EIP. All awards previously granted under the EIP that are still outstanding remain valid and continue to be subject to all of the terms and conditions of the EIP. At Dec. 31, 2011, non-qualified stock options, restricted stock and performance shares were outstanding under the EIP and another predecessor plan under which new awards can no longer be granted. Alliant Energy satisfies payouts related to equity awards under the OIP and EIP through the issuance of new shares of its common stock. Alliant Energy also has the Alliant Energy Director Long Term Incentive Plan (DLIP), which permits the grant of long-term incentive awards, including performance units and restricted cash awards to certain key employees. At Dec. 31, 2011, performance units and performance contingent cash awards were

outstanding under the DLIP. There is no limit to the number of grants that can be made under the DLIP and Alliant Energy satisfies all payouts under the DLIP through cash.

A summary of compensation expense and the related income tax benefits recognized for share-based compensation awards was as follows (in millions):

	Alliant Energy						IPL						WPL
	2011		2010		2009		2011		2010		2009		2011		2010		2009
Compensation expense	$	10.1	$	7.5	$	2.8	$	5.5	$	4.0	$	1.6	$	4.1	$	3.0	$	1.1
Income tax benefits		4.0		3.0		1.2		2.2		1.6		0.7		1.7		1.2		0.4

As of Dec. 31, 2011, total unrecognized compensation cost related to nonvested share-based compensation awards was $9.3 million, which is expected to be recognized over a weighted average period between one and two years. Share-based compensation expense is recognized on a straight-line basis over the requisite service periods and is primarily recorded in "Utility - other operation and maintenance" in the Consolidated Statements of Income.

Performance Shares and Units - Payouts of performance shares and units to key employees are contingent upon achievement over three-year periods of specified performance criteria, which currently include metrics of total shareowner return relative to investor-owned utility peer groups. Payouts of nonvested performance shares and units issued prior to 2012 are prorated at retirement, death, disability or involuntary termination without cause based on time worked during the performance period and achievement of the performance criteria. Participants' nonvested performance shares and units issued prior to 2012 are forfeited if the participant voluntarily leaves Alliant Energy or is terminated for cause. Nonvested performance shares and units do not have non-forfeitable rights to dividends when dividends are paid to common shareowners. Alliant Energy anticipates making future payouts of its performance shares and units in cash; therefore, performance shares and units are accounted for as liability awards.

Performance Shares - Performance shares can be paid out in shares of Alliant Energy's common stock, cash or a combination of cash and stock and are adjusted by a performance multiplier, which ranges from zero to 200% based on the performance criteria. A summary of the performance shares activity was as follows:

	2011			2010			2009
	Shares (a)			Shares (a)			Shares (a)
Nonvested shares, Jan. 1		234,518			256,579			208,579
Granted		64,217			72,487			152,735
Vested (b)		(57,838	)		—			(84,633	)
Forfeited (c)		(3,918	)		(94,548	)		(20,102	)
Nonvested shares, Dec. 31		236,979			234,518			256,579

(a) Share amounts represent the target number of performance shares. Each performance share's value is based on the price of one share of Alliant Energy's common stock at the end of the performance period. The actual number of shares that will be paid out upon vesting is dependent upon actual performance and may range from zero to 200% of the target number of shares.

(b) In 2011, 57,838 performance shares granted in 2008 vested at 75% of the target, resulting in a payout valued at $1.6 million, which consisted of a combination of cash and common stock (1,387 shares). In 2009, 84,633 performance shares granted in 2006 vested resulting in a payout valued at $4.1 million, which consisted of a combination of cash and common stock (51,189 shares).

(c) In 2010, 57,100 performance shares granted in 2007 were forfeited without payout because the specified performance criteria for such shares were not met. The remaining forfeitures during 2011, 2010 and 2009 were primarily caused by retirements and voluntary terminations of participants.

Performance Units - Alliant Energy granted share-based compensation awards to key employees in 2011 and 2010 referred to as performance units. The performance units and the performance contingent cash awards discussed below were granted in 2011 and 2010 in lieu of time-based restricted stock. Performance units must be paid out in cash and are adjusted by a performance multiplier, which ranges from zero to 200% based on the performance criteria. A summary of the performance unit activity was as follows:

	2011			2010
	Units (a)			Units (a)
Nonvested units, Jan. 1		23,128			—
Granted		23,975			23,795
Forfeited		(4,107	)		(667	)
Nonvested units, Dec. 31		42,996			23,128

(a) Unit amounts represent the target number of performance units. Each performance unit's value is based on the average price of one share of Alliant Energy's common stock on the grant date of the award. The actual payout for performance units is dependent upon actual performance and may range from zero to 200% of the target number of units.

Fair Value of Awards - Information

 related to fair values of nonvested performance shares and units at Dec. 31, 2011, by year of grant, were as follows:

	Performance Shares									Performance Units
	2011 Grant			2010 Grant			2009 Grant			2011 Grant			2010 Grant
Nonvested awards		62,170			62,829			111,980			22,279			20,717
Alliant Energy common stock closing price on Dec. 31, 2011	$	44.11		$	44.11		$	44.11
Alliant Energy common stock average price on grant date										$	38.75		$	32.56
Estimated payout percentage based on performance criteria		106	%		155	%		163	%		106	%		155	%
Fair values of each nonvested award	$	46.76		$	68.37		$	71.68		$	41.08		$	50.46

At Dec. 31, 2011, fair values of nonvested performance shares and units were calculated using a Monte Carlo simulation to determine the anticipated total shareowner returns of Alliant Energy and its investor-owned utility peer groups. Expected volatility was based on historical volatilities using daily stock prices over the past three years. Expected dividend yields were calculated based on the most recent quarterly dividend rates announced prior to the measurement date and stock prices at the measurement date. The risk-free interest rate was based on the three-year U.S. Treasury rate in effect as of the measurement date.

Restricted Stock - Restricted stock issued under the EIP consists of time-based and performance-contingent restricted stock.

Time-based Restricted Stock - The current restriction period for outstanding time-based restricted stock is up to three years. Nonvested shares of time-based restricted stock generally become vested upon retirement. Compensation costs related to awards granted to retirement-eligible employees are generally expensed on the date of grant. Participants' nonvested time-based restricted stock issued prior to 2012 is forfeited if the participant voluntarily leaves Alliant Energy or is terminated for cause. Nonvested time-based restricted stock issued prior to 2012 is fully vested in the event of retirement, death, disability or involuntary termination without cause. The fair value of time-based restricted stock is based on the average market price at the grant date. A summary of the time-based restricted stock activity was as follows:

	2011					2010					2009
	Shares			Weighted Average Fair Value		Shares			Weighted Average Fair Value		Shares			Weighted Average Fair Value
Nonvested shares, Jan. 1		70,033		$	32.27		125,349		$	32.47		156,807		$	32.80
Granted		5,000			39.86		—			—		51,236			29.40
Vested		(38,633	)		34.60		(54,016	)		32.72		(79,459	)		31.08
Forfeited		(600	)		29.41		(1,300	)		32.78		(3,235	)		33.97
Nonvested shares, Dec. 31		35,800			30.87		70,033			32.27		125,349			32.47

Performance-contingent Restricted Stock - Vesting of performance-contingent restricted stock grants are based on the achievement of certain performance targets (currently specified earnings growth). The performance metric for the 2011, 2010 and 2009 grants is consolidated net income growth. If performance targets are not met within the performance period, which currently ranges from two to four years, these restricted stock grants are forfeited. Nonvested shares of performance- contingent restricted stock issued prior to 2012 are prorated at retirement based on time worked during the performance period and vest only if and when the performance criteria are met. Participants' nonvested performance-contingent restricted stock issued prior to 2012 is forfeited if the participant voluntarily leaves Alliant Energy for reasons other than retirement. The fair value of performance-contingent restricted stock is based on the average market price at the grant date. A summary

of the performance-contingent restricted stock activity was as follows:

	2011					2010					2009
	Shares			Weighted Average Fair Value		Shares			Weighted Average Fair Value		Shares		Weighted Average Fair Value
Nonvested shares, Jan. 1		296,190		$	32.32		226,007		$	32.25		124,185	$	39.28
Granted		64,217			38.75		72,487			32.56		101,822		23.67
Vested		(53,274	)		37.93		—			—		—		—
Forfeited		(5,395	)		38.00		(2,304	)		32.56		—		—
Nonvested shares, Dec. 31		301,738			32.60		296,190			32.32		226,007		32.25

Non-qualified Stock Options - Options granted under the plans were granted at the market price of the shares on the date of grant, vest over three years and expire no later than 10 years after the grant date. Options become fully vested upon retirement and remain exercisable at any time prior to their expiration date or for three years after the effective date of the retirement, whichever period is shorter. Options become fully vested upon death or disability and remain exercisable at any time prior to their expiration date or for one year after the effective date of the death or disability, whichever period is shorter. If participants leave Alliant Energy for reasons other than retirement, death or disability, their options that are not vested are forfeited and their vested options expire three months after their departure. Alliant Energy has not granted any options since 2004. A summary of the stock option activity was as follows:

	2011					2010					2009
	Shares			Weighted Average Exercise Price		Shares			Weighted Average Exercise Price		Shares			Weighted Average Exercise Price
Outstanding, Jan. 1		163,680		$	24.51		384,331		$	27.02		497,183		$	27.30
Exercised		(99,791	)		24.71		(191,433	)		28.93		(39,877	)		25.80
Expired		—			—		(29,218	)		28.59		(56,098	)		29.88
Forfeited		—			—		—			—		(16,877	)		28.67
Outstanding and exercisable, Dec. 31		63,889			24.21		163,680			24.51		384,331			27.02

The weighted average remaining contractual term

for options outstanding and exercisable at Dec. 31, 2011 was between one and two years. The aggregate intrinsic value of options outstanding and exercisable at Dec. 31, 2011 was $1.3 million.

Other information related to stock option activity was as follows (in millions):

	2011		2010		2009
Cash received from stock options exercised	$	2.5	$	5.5	$	1.0
Aggregate intrinsic value of stock options exercised		1.6		1.1		0.1
Income tax benefit from the exercise of stock options		0.7		0.4		0.1

Performance Contingent Cash Awards - Alliant Energy granted share-based compensation awards to key employees in 2011 and 2010 referred to as performance contingent cash awards. Performance contingent cash award payouts to key employees are based on the achievement of certain performance targets (currently specified consolidated net income growth). If performance targets are not met within the performance period, which currently ranges from two to four years, there are no payouts for these awards. Nonvested awards issued prior to 2012 are prorated at retirement based on time worked during the performance period and achievement of the performance criteria. Participants' nonvested awards issued prior to 2012 are forfeited if the participant voluntarily leaves Alliant Energy for reasons other than retirement. Each performance contingent cash award's value is based on the price of one share of Alliant Energy's common stock at the end of the performance period. Alliant Energy accounts for performance contingent cash awards as liability awards because payouts will be made in the form of cash. A summary of the performance contingent cash awards activity was as follows:

	2011			2010
	Awards			Awards
Nonvested awards, Jan. 1		23,428			—
Granted		23,975			23,795
Forfeited		(727	)		(367	)
Nonvested awards, Dec. 31		46,676			23,428

(c) Deferred Compensation Plan - Alliant Energy maintains a deferred compensation plan under which key employees may defer up to 100% of base salary and incentive compensation and directors may elect to defer all or part of their retainer and committee fees. Key employees who have made the maximum allowed contribution to the Alliant Energy 401(k) Savings Plan may receive an additional credit to the deferred compensation plan. Key employees and directors may elect to have their deferrals credited to a company stock account, an interest account or equity accounts based on index funds.

Company Stock Accounts - The deferred compensation plan does not permit diversification of deferrals credited to the company stock account and all distributions from participants' company stock accounts are made in the form of shares of Alliant Energy common stock. The deferred compensation obligations for participants' company stock accounts are recorded in "Additional paid-in capital" and the shares of Alliant Energy common stock held in a rabbi trust to satisfy this obligation are recorded in "Shares in deferred compensation trust" on Alliant Energy's Consolidated Balance Sheets. At Dec. 31, the carrying value of the deferred compensation obligation for the company stock accounts and the shares in the deferred compensation trust based on the historical value of the shares of Alliant Energy common stock contributed to the rabbi trust, and the fair market value of the shares held in the rabbi trust were as follows (in millions):

	2011		2010
Carrying value	$	8.3	$	7.6
Fair market value		11.6		9.1

Interest and Equity Accounts - Distributions from participants' interest and equity accounts are in the form of cash payments. The deferred compensation obligations for participants' interest and equity accounts are recorded in "Pension and other benefit obligations" on Alliant Energy's and IPL's Consolidated Balance Sheets. At Dec. 31, the carrying value of Alliant Energy's and IPL's deferred compensation obligations for participants' interest and equity accounts was as follows (in millions):

	Alliant Energy				IPL
	2011		2010		2011		2010
Carrying value	$	20.5	$	20.5	$	5.0	$	5.2

IPL [Member]

Benefit Plans

(6) BENEFIT PLANS

(a) Pension and Other Postretirement Benefits Plans - Alliant Energy, IPL and WPL provide retirement benefits to substantially all of their employees through various qualified and non-qualified non-contributory defined benefit pension plans, and through defined contribution plans (including 401(k) savings plans). Alliant Energy's, IPL's and WPL's qualified and non-qualified non-contributory defined benefit pension plans are currently closed to new hires. Benefits of the non-contributory defined benefit pension plans are based on the plan participant's years of service, age and compensation. Benefits of the defined contribution plans are based on the plan participant's years of service, age, compensation and contributions. Alliant Energy, IPL and WPL also provide certain defined benefit postretirement health care and life benefits to eligible retirees. In general, the retiree health care plans consist of fixed benefit subsidy structures and the retiree life insurance plans are non-contributory.

Assumptions - The assumptions for Alliant Energy's, IPL's and WPL's defined benefit pension and other postretirement benefits plans at the measurement date of Dec. 31 were as follows (Not Applicable (N/A)):

Alliant Energy

	Defined Benefit Pension Plans			Other Postretirement Benefits Plans
	2011	2010	2009	2011	2010	2009
Discount rate for benefit obligations	4.86%	5.56%	5.8%	4.6%	5.25%	5.55%
Discount rate for net periodic cost	5.56%	5.8%	6.15%	5.25%	5.55%	6.15%
Expected rate of return on plan assets	7.9%	8%	8.25%	7%	6.9%	8.25%
Rate of compensation increase	3.5-4.5%	3.5-4.5%	3.5-4.5%	3.5%	3.5%	3.5%
Medical cost trend on covered charges:
Initial trend rate (end of year)	N/A	N/A	N/A	8%	7%	7.5%
Ultimate trend rate	N/A	N/A	N/A	5%	5%	5%
IPL
	Qualified Defined Benefit Pension Plans			Other Postretirement Benefits Plans
	2011	2010	2009	2011	2010	2009
Discount rate for benefit obligations	4.95%	5.7%	5.8%	4.6%	5.25%	5.55%
Discount rate for net periodic cost	5.7%	5.8%	6.15%	5.25%	5.55%	6.15%
Expected rate of return on plan assets	7.9%	8%	8.25%	7.3%	7.1%	8.25%
Rate of compensation increase	3.5%	3.5%	3.5%	3.5%	3.5%	3.5%
Medical cost trend on covered charges:
Initial trend rate (end of year)	N/A	N/A	N/A	8%	7%	7.5%
Ultimate trend rate	N/A	N/A	N/A	5%	5%	5%

WPL

	Qualified Defined Benefit Pension Plans			Other Postretirement Benefits Plans
	2011	2010	2009	2011	2010	2009
Discount rate for benefit obligations	4.95%	5.7%	5.8%	4.6%	5.25%	5.55%
Discount rate for net periodic cost	5.7%	5.8%	6.15%	5.25%	5.55%	6.15%
Expected rate of return on plan assets	7.9%	8%	8.25%	6.3%	6.3%	8.25%
Rate of compensation increase	3.5%	3.5%	3.5%	3.5%	3.5%	3.5%
Medical cost trend on covered charges:
Initial trend rate (end of year)	N/A	N/A	N/A	8%	7%	7.5%
Ultimate trend rate	N/A	N/A	N/A	5%	5%	5%

Expected rate of return on plan assets - The expected rate of return on plan assets is determined by analysis of projected asset class returns based on the target asset class allocations. Alliant Energy uses a portfolio return simulator and also reviews historical returns, survey information and capital market information to support the expected rate of return on plan assets assumption. Refer to "Investment Policy and Strategy for Plan Assets" below for additional information related to Alliant Energy's investment policy and strategy and mix of assets for the pension and other postretirement benefits plans.

Medical cost trend on covered charges - The assumed medical trend rates are critical assumptions in determining the service and interest cost and accumulated postretirement benefit obligation related to postretirement benefits costs. A 1% change in the medical trend rates for 2011, holding all other assumptions constant, would have the following effects (in millions):

	Alliant Energy					IPL					WPL
	1% Increase		1% Decrease			1% Increase		1% Decrease			1% Increase		1% Decrease
Effect on total of service and interest cost components	$	0.5		($0.4	)	$	0.2		($0.2	)	$	0.2		($0.2	)
Effect on postretirement benefit obligation		2.9		(2.8	)		1.3		(1.2	)		1.5		(1.4	)

Net Periodic Benefit Costs - In the "IPL" and "WPL" tables below, the qualified defined benefit pension plans costs represent only those respective costs for bargaining unit employees of IPL and WPL covered under the plans that are sponsored by IPL and WPL, respectively. Also in the "IPL" and "WPL" tables, the other postretirement benefits costs represent costs for all IPL and WPL employees, respectively. The "Directly assigned defined benefit pension plans" tables include amounts directly assigned to each of IPL and WPL related to IPL's and WPL's current and former non-bargaining employees who are participants in Alliant Energy and Corporate Services sponsored qualified and non-qualified defined benefit pension plans. The components of Alliant Energy's, IPL's and WPL's net periodic benefit costs for their sponsored defined benefit pension and other postretirement benefits plans, and defined benefit pension plans amounts directly assigned to IPL and WPL,as recognized on Alliant Energy's, IPL's and WPL's Consolidated Statements of Income, were as follows (in millions):

Alliant Energy

	Defined Benefit Pension Plans									Other Postretirement Benefits Plans (a)
	2011			2010			2009			2011			2010			2009
Service cost	$	11.4		$	11.9		$	11.9		$	7.0		$	9.3		$	8.7
Interest cost		52.0			52.3			54.3			12.3			14.9			15.2
Expected return on plan assets (b)		(63.8	)		(62.1	)		(47.6	)		(7.9	)		(7.7	)		(6.1	)
Amortization of (c):
Transition obligation		—			—			—			—			0.1			0.2
Prior service cost (credit)		0.7			0.9			2.1			(10.0	)		(2.4	)		(3.7	)
Actuarial loss		21.1			23.8			30.6			5.3			7.4			6.2
Additional benefit costs (d)		10.2			—			—			—			—			—
Settlement losses (e)		1.1			1.4			—			—			—			—
Curtailment losses (f)(g)		—			—			1.0			—			—			—
Special termination benefits costs (g)		—			—			0.9			—			—			—
	$	32.7		$	28.2		$	53.2		$	6.7		$	21.6		$	20.5

IPL

	Qualified Defined Benefit Pension Plans									Other Postretirement Benefits Plans (a)
	2011			2010			2009			2011			2010			2009
Service cost	$	6.1		$	6.2		$	6.1		$	2.6		$	3.4		$	3.1
Interest cost		16.7			16.5			16.1			5.5			6.8			7.3
Expected return on plan assets (b)		(20.0	)		(19.5	)		(14.0	)		(5.4	)		(5.3	)		(4.2	)
Amortization of (c):
Transition obligation		—			—			—			—			0.1			0.2
Prior service cost (credit)		0.5			0.6			0.8			(5.0	)		(1.1	)		(1.6	)
Actuarial loss		5.7			7.2			9.3			2.9			4.0			4.0
	$	9.0		$	11.0		$	18.3		$	0.6		$	7.9		$	8.8
WPL
	Qualified Defined Benefit Pension Plan									Other Postretirement Benefits Plans (a)
	2011			2010			2009			2011			2010			2009
Service cost	$	4.5		$	4.9		$	4.9		$	2.9		$	3.6		$	3.4
Interest cost		16.1			15.7			15.5			4.9			5.5			5.5
Expected return on plan assets (b)		(20.0	)		(19.1	)		(14.1	)		(1.3	)		(1.3	)		(1.1	)
Amortization of (c):
Prior service cost (credit)		0.5			0.5			0.5			(3.4	)		(0.7	)		(0.9	)
Actuarial loss		7.1			8.5			10.4			2.1			2.5			1.3
Curtailment loss (f)		—			—			0.7			—			—			—
Special termination benefits costs (g)		—			—			0.9			—			—			—
	$	8.2		$	10.5		$	18.8		$	5.2		$	9.6		$	8.2
Directly assigned defined benefit pension plans	IPL									WPL
	2011			2010			2009			2011			2010			2009
Interest cost	$	7.3		$	7.8		$	8.7		$	5.5		$	5.6		$	6.1
Expected return on plan assets (b)		(9.7	)		(9.7	)		(8.4	)		(7.3	)		(7.3	)		(6.3	)
Amortization of (c):
Prior service credit		(0.2	)		(0.3	)		(0.1	)		(0.2	)		(0.2	)		—
Actuarial loss		3.0			2.9			4.2			3.0			2.8			3.6
Additional benefit costs (d)		2.8			—			—			0.7			—			—
Curtailment gain		—			—			(0.1	)		—			—			—
	$	3.2		$	0.7		$	4.3		$	1.7		$	0.9		$	3.4

(a) In May 2011, Alliant Energy, IPL and WPL amended their defined benefit postretirement health care plans resulting in a revision to the method and level of coverage provided for participants more than 65 years of age. This amendment was determined to be a significant event, which required Alliant Energy, IPL and WPL to remeasure their defined benefit postretirement health care plans in May 2011. The amendment resulted in a decrease in Alliant Energy's, IPL's and WPL's postretirement benefit obligations of $55 million, $30 million and $16 million, respectively, in 2011 with the impact of the remeasurement on net periodic benefit costs being recognized prospectively from the remeasurement date. The impact of the remeasurement decreased Alliant Energy's, IPL's and WPL's net periodic benefit costs by $11.3 million, $7.2 million, and $3.8 million in 2011, respectively. The discount rate used for the remeasurement was 5.20%. All other assumptions used for the remeasurement were consistent with the measurement assumptions used at Dec. 31, 2010.

(b) The expected return on plan assets is based on the expected rate of return on plan assets and the fair value approach to the market-related value of plan assets.

(c) Unrecognized net actuarial gains or losses in excess of 10% of the greater of the plans' benefit obligation or asset are amortized over the average future service lives of plan participants, except for the Alliant Energy Cash Balance Pension Plan (Cash Balance Plan) where gains or losses outside the 10% threshold are amortized over the time period the participants are expected to receive benefits. Unrecognized prior service costs (credits) for the postretirement benefits plans are amortized over the average future service period to full eligibility of the participants of each plan.

(d) Alliant Energy reached an agreement with the IRS, which resulted in a favorable determination letter for the Cash Balance Plan in 2011. The agreement with the IRS required Alliant Energy to amend the Cash Balance Plan, which was completed in 2011 resulting in aggregate additional benefits of $10.2 million paid to certain former participants in the Cash Balance Plan in 2011. Alliant Energy recognized $10.2 million ($6.3 million at IPL ($2.8 million directly assigned and $3.5 million allocated by Corporate Services) and $3.4 million at WPL ($0.7 million directly assigned and $2.7 million allocated by Corporate Services)) of additional benefits costs in 2011 related to these benefits. Refer to Note 13(b) for additional information regarding the Cash Balance Plan.

(e) In 2011 and 2010, the settlement losses of $1.1 million and $1.4 million, respectively, related to payments made to retired executives of Alliant Energy.

(f) In 2007, members of the International Brotherhood of Electrical Workers Local 965 ratified a four-year collective bargaining agreement reached with WPL, resulting in changes to WPL's qualified pension plan. One of these changes provided WPL qualified pension plan participants an option to cease participating in the WPL qualified pension plan and begin participating in the Alliant Energy 401(k) Savings Plan with increased levels of contribution by Alliant Energy. The election of this option did not impact a participant's eligibility for benefits previously vested under the WPL qualified pension plan. In 2009, certain of these employees elected to cease participating in the WPL qualified pension plan, resulting in Alliant Energy and WPL recognizing a curtailment loss related to the WPL qualified pension plan of $0.7 million in 2009.

(g) In 2009, Alliant Energy eliminated certain corporate and operations positions. As a result, Alliant Energy recognized curtailment losses related to its pension plans of $0.3 million in 2009. In addition, Alliant Energy and WPL recognized special termination benefits costs related to the qualified defined benefit pension plan that is sponsored by WPL of $0.9 million in 2009.

Corporate Services provides services to IPL and WPL, and as a result, IPL and WPL are allocated pension and other postretirement benefits costs associated with Corporate Services employees. The following table includes the allocated qualified and non-qualified pension and other postretirement benefits costs associated with Corporate Services employees providing services to IPL and WPL (in millions):

	Pension Benefits Costs (a)						Other Postretirement Benefits Costs
	2011		2010		2009		2011		2010		2009
IPL	$	5.8	$	2.9	$	5.1	$	0.3	$	2.0	$	1.8
WPL		4.2		1.9		3.2		0.2		1.3		1.2

(a) In 2011, additional qualified pension benefits costs resulting from the 2011 amendment to the Cash Balance Plan allocated to IPL and WPL by Corporate Services were $3.5 million and $2.7 million, respectively.

The estimated amortization from "Regulatory assets" and "Regulatory liabilities" on the Consolidated Balance Sheets and "Accumulated other comprehensive loss" (AOCL) on Alliant Energy's Consolidated Balance Sheet into net periodic benefit cost in 2012 is as follows (in millions):

	Alliant Energy					IPL					WPL
	Defined Benefit Pension Plans		Other Postretirement Benefits Plans			Qualified Defined Benefit Pension Plans		Other Postretirement Benefits Plans			Qualified Defined Benefit Pension Plans		Other Postretirement Benefits Plans
Actuarial loss	$	33.2	$	6.3		$	10.2	$	3.6		$	12.1	$	2.3
Prior service cost (credit)		0.3		(12.0	)		0.4		(6.3	)		0.5		(3.9	)
	$	33.5		($5.7	)	$	10.6		($2.7	)	$	12.6		($1.6	)

Directly assigned defined benefit pension plans	IPL			WPL
Actuarial loss	$	3.9		$	3.6
Prior service credit		(0.2	)		(0.1	)
	$	3.7		$	3.5

In addition to the estimated amortizations from "Regulatory assets" in the above tables for IPL and WPL, $1.9 million and $1.2 million, respectively, of amortizations are expected in 2012 from "Regulatory assets" associated with Corporate Services employees participating in other Alliant Energy sponsored plans allocated to IPL and WPL.

Alliant Energy's, IPL's and WPL's net periodic benefit costs are primarily included in "Utility - other operation and maintenance" in the Consolidated Statements of Income.

Benefit Plan Assets and Obligations - A reconciliation of the funded status of Alliant Energy's qualified and non-qualified defined benefit pension and other postretirement benefits plans to the amounts recognized on Alliant Energy's Consolidated Balance Sheets at Dec. 31 was as follows (in millions):

Alliant Energy

	Defined Benefit Pension Plans						Other Postretirement Benefits Plans
	2011			2010			2011			2010
Change in projected benefit obligation:
Net projected benefit obligation at Jan. 1	$	953.0		$	920.1		$	274.9		$	268.4
Service cost		11.4			11.9			7.0			9.3
Interest cost		52.0			52.3			12.3			14.9
Plan participants' contributions		—			—			6.4			5.6
Plan amendments (a)		10.2			—			(56.6	)		(3.1	)
Actuarial (gain) loss		126.2			27.0			(0.8	)		(0.2	)
Early Retiree Reinsurance Program (ERRP) proceeds		—			—			0.6			—
Gross benefits paid		(71.4	)		(58.3	)		(20.8	)		(21.2	)
Federal subsidy on other postretirement benefits paid		—			—			1.2			1.2
Net projected benefit obligation at Dec. 31		1,081.4			953.0			224.2			274.9
Change in plan assets:
Fair value of plan assets at Jan. 1		823.0			776.4			122.7			102.4
Actual return on plan assets		28.9			96.9			2.6			14.0
Employer contributions		116.9			8.0			9.5			21.9
Plan participants' contributions		—			—			6.4			5.6
Gross benefits paid		(71.4	)		(58.3	)		(20.8	)		(21.2	)
Fair value of plan assets at Dec. 31		897.4			823.0			120.4			122.7
Under funded status at Dec. 31		($184.0	)		($130.0	)		($103.8	)		($152.2	)
Amounts recognized on the Consolidated Balance Sheets consist of:
Non-current assets	$	—		$	—		$	1.3		$	—
Other current liabilities		(4.6	)		(6.9	)		—			—
Pension and other benefit obligations		(179.4	)		(123.1	)		(105.1	)		(152.2	)
Net amount recognized at Dec. 31		($184.0	)		($130.0	)		($103.8	)		($152.2	)

Amounts recognized in Regulatory Assets, Regulatory Liabilities and AOCL consist of (b):
Net actuarial loss	$	494.8		$	356.0		$	76.7		$	77.1
Prior service credit		(6.9	)		(6.2	)		(52.5	)		(5.7	)
	$	487.9		$	349.8		$	24.2		$	71.4

(a) Refer to "Net Periodic Benefit Costs" above for additional information regarding plan amendments to the defined benefit pension and other postretirement benefits plans in 2011.

(b) Refer to Note 1(b) and Alliant Energy's Consolidated Statements of Common Equity for amounts recognized in "Regulatory assets" and "AOCL," respectively, on Alliant Energy's Consolidated Balance Sheets. At Dec. 31, 2011, $3.3 million of regulatory liabilities were recognized related to Alliant Energy's other postretirement benefits plans.

A reconciliation of the funded status of IPL's and WPL's sponsored qualified defined benefit pension and other postretirement benefits plans to the amounts recognized on IPL's and WPL's Consolidated Balance Sheets, at Dec. 31 was as follows (in millions):

IPL

	Qualified Defined Benefit Pension Plans						Other Postretirement Benefits Plans
	2011			2010			2011			2010
Change in projected benefit obligation:
Net projected benefit obligation at Jan. 1	$	293.8		$	284.3		$	128.5		$	123.9
Service cost		6.1			6.2			2.6			3.4
Interest cost		16.7			16.5			5.5			6.8
Plan participants' contributions		—			—			2.0			1.6
Plan amendments (a)		—			—			(30.1	)		(1.7	)
Actuarial (gain) loss		45.2			3.1			(2.7	)		4.0
ERRP proceeds		—			—			0.2			—
Gross benefits paid		(17.3	)		(16.3	)		(9.1	)		(10.1	)
Federal subsidy on other postretirement benefits paid		—			—			0.6			0.6
Net projected benefit obligation at Dec. 31		344.5			293.8			97.5			128.5
Change in plan assets:
Fair value of plan assets at Jan. 1		256.9			242.8			77.5			68.4
Actual return on plan assets		9.1			30.4			1.4			9.6
Employer contributions		50.0			—			2.9			8.0
Plan participants' contributions		—			—			2.0			1.6
Gross benefits paid		(17.3	)		(16.3	)		(9.1	)		(10.1	)
Fair value of plan assets at Dec. 31		298.7			256.9			74.7			77.5
Under funded status at Dec. 31		($45.8	)		($36.9	)		($22.8	)		($51.0	)
Amounts recognized on the Consolidated Balance Sheets consist of:

Pension and other benefit obligations		($45.8	)		($36.9	)		($22.8	)		($51.0	)
Amounts recognized in Regulatory Assets and Regulatory Liabilities consist of (b):
Net actuarial loss	$	141.1		$	90.8		$	41.0		$	42.4
Prior service cost (credit)		1.1			1.6			(27.6	)		(2.5	)
	$	142.2		$	92.4		$	13.4		$	39.9

WPL

	Qualified Defined Benefit Pension Plan						Other Postretirement Benefits Plans
	2011			2010			2011			2010
Change in projected benefit obligation:
Net projected benefit obligation at Jan. 1	$	283.3		$	271.6		$	103.3		$	99.1
Service cost		4.5			4.9			2.9			3.6
Interest cost		16.1			15.7			4.9			5.5
Plan participants' contributions		—			—			3.3			3.2
Plan amendments (a)		—			—			(18.2	)		(1.5	)
Actuarial loss		43.3			2.5			2.3			1.9
ERRP proceeds		—			—			0.2			—
Gross benefits paid		(14.7	)		(11.4	)		(9.6	)		(9.0	)
Federal subsidy on other postretirement benefits paid		—			—			0.5			0.5
Net projected benefit obligation at Dec. 31		332.5			283.3			89.6			103.3
Change in plan assets:
Fair value of plan assets at Jan. 1		255.2			236.6			25.0			18.8
Actual return on plan assets		9.1			30.0			0.9			2.1
Employer contributions		40.0			—			5.5			9.9
Plan participants' contributions		—			—			3.3			3.2
Gross benefits paid		(14.7	)		(11.4	)		(9.6	)		(9.0	)
Fair value of plan assets at Dec. 31		289.6			255.2			25.1			25.0
Under funded status at Dec. 31		($42.9	)		($28.1	)		($64.5	)		($78.3	)

WPL

	Qualified Defined Benefit Pension Plan						Other Postretirement Benefits Plans
	2011			2010			2011			2010
Amounts recognized on the Consolidated Balance Sheets consist of:
Non-current asset	$	—		$	—		$	1.3		$	—
Pension and other benefit obligations		(42.9	)		(28.1	)		(65.8	)		(78.3	)
Net amount recognized at Dec. 31		($42.9	)		($28.1	)		($64.5	)		($78.3	)
Amounts recognized in Regulatory Assets:
Net actuarial loss	$	142.7		$	95.6		$	27.8		$	27.2
Prior service cost (credit)		2.4			2.9			(17.3	)		(2.5	)
	$	145.1		$	98.5		$	10.5		$	24.7

(a) Refer to "Net Periodic Benefit Costs" above for additional information regarding plan amendments to the defined benefit pension and other postretirement benefits plans in 2011.

(b) At Dec. 31, 2011, $2.8 million of regulatory liabilities were recognized related to IPL's other postretirement benefits plans.

Included in the following tables are Alliant Energy's, IPL's and WPL's accumulated benefit obligations, aggregate amounts applicable to defined benefit pension and other postretirement benefits plans with accumulated benefit obligations in excess of plan assets, as well as defined benefit pension plans with projected benefit obligations in excess of plan assets as of the Dec. 31 measurement date (Not Applicable (N/A); in millions):

Alliant Energy

	Defined Benefit Pension Plans				Other Postretirement Benefits Plans
	2011		2010		2011		2010
Accumulated benefit obligations	$	1,029.4	$	915.5	$	224.2	$	274.9
Plans with accumulated benefit obligations in excess of plan assets:
Accumulated benefit obligations		1,029.4		915.5		224.2		274.9
Fair value of plan assets		897.4		823.0		120.4		122.7
Plans with projected benefit obligations in excess of plan assets:
Projected benefit obligations		1,081.4		953.0		N/A		N/A
Fair value of plan assets		897.4		823.0		N/A		N/A

IPL

	Qualified Defined Benefit Pension Plans				Other Postretirement Benefits Plans
	2011		2010		2011		2010
Accumulated benefit obligations	$	314.6	$	274.1	$	97.5	$	128.5
Plans with accumulated benefit obligations in excess of plan assets:
Accumulated benefit obligations		314.6		274.1		97.5		128.5
Fair value of plan assets		298.7		256.9		74.7		77.5
Plans with projected benefit obligations in excess of plan assets:
Projected benefit obligations		344.5		293.8		N/A		N/A
Fair value of plan assets		298.7		256.9		N/A		N/A

WPL

	Qualified Defined Benefit Pension Plans				Other Postretirement Benefits Plans
	2011		2010		2011		2010
Accumulated benefit obligations	$	314.7	$	270.2	$	89.6	$	103.3
Plans with accumulated benefit obligations in excess of plan assets:
Accumulated benefit obligations		314.7		270.2		89.6		103.3
Fair value of plan assets		289.6		255.2		25.1		25.0
Plans with projected benefit obligations in excess of plan assets:
Projected benefit obligations		332.5		283.3		N/A		N/A
Fair value of plan assets		289.6		255.2		N/A		N/A

The "Directly assigned defined benefit pension plans" table below includes amounts directly assigned to each of IPL and WPL related to IPL's and WPL's current and former non-bargaining employees who are participants in Alliant Energy and Corporate Services sponsored qualified and non-qualified defined benefit pension plans. A reconciliation of the funded status of the directly assigned qualified and non-qualified defined benefit pension plans to the amounts recognized on IPL's and WPL's Consolidated Balance Sheets at Dec. 31 was as follows (in millions):

Directly assigned defined benefit pension plans

	IPL						WPL
	2011			2010			2011			2010
Change in projected benefit obligation:
Net projected benefit obligation at Jan. 1	$	144.4		$	138.8		$	107.4		$	100.9
Interest cost		7.3			7.8			5.5			5.6
Plan amendments		2.8			—			0.7			—
Actuarial loss		13.2			8.0			10.3			8.7
Gross benefits paid		(12.3	)		(10.2	)		(8.7	)		(7.8	)
Net projected benefit obligation at Dec. 31		155.4			144.4			115.2			107.4
Change in plan assets:
Fair value of plan assets at Jan. 1		127.6			121.6			95.6			92.0
Actual return on plan assets		4.2			15.1			3.2			11.2
Employer contributions		7.9			1.1			6.9			0.2
Gross benefits paid		(12.3	)		(10.2	)		(8.7	)		(7.8	)
Fair value of plan assets at Dec. 31		127.4			127.6			97.0			95.6
Under funded status at Dec. 31		($28.0	)		($16.8	)		($18.2	)		($11.8	)
Amounts recognized on the Consolidated Balance Sheets consist of:
Other current liabilities		($0.8	)		($1.0	)		($0.2	)		($0.1	)
Pension and other benefit obligations		(27.2	)		(15.8	)		(18.0	)		(11.7	)
Net amount recognized at Dec. 31		($28.0	)		($16.8	)		($18.2	)		($11.8	)
Amounts recognized in Regulatory Assets:
Net actuarial loss	$	76.2		$	60.5		$	73.7		$	62.3
Prior service credit		(3.4	)		(3.6	)		(2.4	)		(2.6	)
	$	72.8		$	56.9		$	71.3		$	59.7
Accumulated benefit obligations	$	155.4		$	144.4		$	115.2		$	107.4

In addition to the amounts recognized in "Regulatory assets and regulatory liabilities" in the above tables for IPL and WPL, "Regulatory assets" and "Regulatory liabilities" were recognized for amounts associated with Corporate Services employees participating in other Alliant Energy sponsored benefit plans that were allocated to IPL and WPL at Dec. 31 as follows (in millions):

	IPL				WPL
	2011		2010		2011		2010
Regulatory assets	$	33.7	$	28.2	$	22.3	$	18.6
Regulatory liabilities		0.3		—		0.2		—

Estimated Future Employer Contributions and Benefit Payments - Alliant Energy, IPL, and WPL estimate that funding for the qualified defined benefit pension, non-qualified defined benefit pension and other postretirement benefits plans, and the directly assigned qualified and non-qualified defined benefit pension plans amounts, during 2012 will be as follows (in millions):

	Alliant Energy		IPL			WPL
Qualified defined benefit pension plans		$—	$	—		$	—
Non-qualified defined benefit pension plans		17.0			(a)			(a)
Directly assigned defined benefit pension plans (b)		N/A		0.8			0.2
Other postretirement benefits plans		4.9		0.6			3.9

(a) Alliant Energy sponsors several non-qualified defined benefit pension plans that cover certain current and former key employees of IPL and WPL. Alliant Energy allocates pension costs to IPL and WPL for these plans.

(b) Amounts directly assigned to IPL and WPL for non-bargaining employees who are participants in Alliant Energy and Corporate Services sponsored qualified and non-qualified defined benefit pension plans.

Alliant Energy's, IPL's and WPL's expected benefit payments, and the directly assigned qualified and non-qualified defined benefit pension benefits amounts, which reflect expected future service, as appropriate, are as follows (in millions):

Alliant Energy

	2012		2013		2014		2015		2016		2017 - 2021
Qualified and non-qualified defined benefit pension benefits	$	58.8	$	59.1	$	62.3	$	66.3	$	65.2	$	355.4
Other postretirement benefits		18.0		18.1		18.4		17.1		17.3		88.7
	$	76.8	$	77.2	$	80.7	$	83.4	$	82.5	$	444.1
IPL
	2012		2013		2014		2015		2016		2017 - 2021
Qualified defined benefit pension benefits	$	15.5	$	16.2	$	17.1	$	18.2		19.2	$	111.6
Directly assigned defined benefit pension benefits		12.1		11.4		12.3		13.0		11.0		57.0
Other postretirement benefits		8.9		8.7		8.6		7.4		7.4		37.0
	$	36.5	$	36.3	$	38.0	$	38.6	$	37.6	$	205.6
WPL
	2012		2013		2014		2015		2016		2017 - 2021
Qualified defined benefit pension benefits	$	13.0	$	13.8	$	14.9	$	15.9	$	17.0	$	103.3
Directly assigned defined benefit pension benefits		9.0		9.4		9.5		9.5		9.2		40.9
Other postretirement benefits		6.8		7.0		7.2		7.1		7.3		37.4
	$	28.8	$	30.2	$	31.6	$	32.5	$	33.5	$	181.6

Investment Policy and Strategy for Plan Assets - Alliant Energy's, IPL's and WPL's investment strategy and their policies employed with respect to assets of defined benefit pension and other postretirement benefits plans are to combine both preservation of principal and prudent and reasonable risk-taking to protect the integrity of plan assets, in order to meet the obligations to plan participants while minimizing benefit costs over the long term. It is recognized that risk and volatility are present with all types of investments. However, high levels of risk are mitigated at the total fund level through diversification by asset class including both U.S. and international equity exposure, the number of individual investments, and sector and industry limits when applicable. Alliant Energy, IPL and WPL also use an overlay management service to help maintain target allocations, liquidity needs and intended exposures to the plan assets. The overlay manager is authorized to use derivative financial instruments to facilitate this service.

Defined Benefit Pension Plans Assets - For assets of defined benefit pension plans, the mix among asset classes is controlled by long-term asset allocation targets. The assets are viewed as long-term with moderate liquidity needs. Historical performance results and future expectations suggest that equity securities will provide higher total investment returns than debt securities over a long-term investment horizon. Consistent with the goals of meeting obligations to plan participants and minimizing benefit costs over the long-term, the defined benefit pension plans have a long-term investment posture more heavily weighted towards equity holdings. The asset allocation mix is monitored regularly and appropriate steps are taken as needed to rebalance the assets within the prescribed range. Prohibited investment vehicles include, but may not be limited to, direct ownership of real estate, options and futures (unless specifically approved as is the case of the overlay manager), margin trading, oil and gas limited partnerships, commodities, short selling and securities of the managers' firms or affiliate firms. At Dec. 31, 2011, the current target range and actual allocations for Alliant Energy's, IPL's and WPL's defined benefit pension plan assets were as follows:

	Target Range	Actual
	Allocation	Allocation
Cash and equivalents (a)	0%-5%		13	%
Equity securities:
U.S. large cap core	10%-20%		12	%
U.S. large cap value	8%-16%		10	%
U.S. large cap growth	8%-16%		10	%
U.S. small cap value	0%-6%		3	%
U.S. small cap growth	0%-4%		2	%
International - developed markets	12%-24%		14	%
International - emerging markets	0%-8%		4	%
Fixed income securities	20%-40%		32	%

(a) Pension contributions of $100 million were made in late December 2011 and were invested in equity futures.

Other Postretirement Benefits Plans Assets - Other postretirement benefits plans assets are comprised of specific assets within certain defined benefit pension plans (401(h) assets) as well as assets held in Voluntary Employees' Beneficiary Association (VEBA) trusts. The investment policy and strategy of the 401(h) assets mirrors those of the defined benefit pension plans, which are discussed above. A mix of both equity and debt securities are utilized to maximize returns and mitigate risk over the long-term. There are no specific target allocations for the VEBA trusts as a whole. Separate investment guidelines have been established for the VEBA trusts which are actively managed. At Dec. 31, 2011, Alliant Energy's, IPL's and WPL's other postretirement benefits plan assets consisted of the following:

	Alliant Energy			IPL			WPL
Equity securities		58	%		63	%		39	%
Fixed income securities		31	%		34	%		19	%
Cash and equivalents		11	%		3	%		42	%

Securities Lending Program - Alliant Energy, IPL and WPL have a securities lending program with a third-party agent that allows the agent to lend certain securities from their defined benefit pension and other postretirement benefits plans to selected entities against receipt of collateral (in the form of cash, government and agency securities or letters of credit) as provided for and determined in accordance with its securities lending agency agreement. Initial collateral levels are no less than 100% of the market value of loans to non-affiliated borrowers of U.S. government securities; 102% of the market value of loans to affiliated borrowers of U.S. government securities; 102% of the market value of loans on U.S. corporate bonds and U.S. equity securities; 105% of the market value of loans on non-U.S. securities; and 102% of the market value of loans on all other securities. Refer to "Fair Value Measurements" below for details of Alliant Energy's, IPL's and WPL's fair value of invested collateral and amounts due to borrowers for the securities lending program.

Fair Value Measurements - The following tables report a framework for measuring fair value. The fair value hierarchy 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. Alliant Energy's, IPL's and WPL's investments in equity and fixed income securities held in registered investment companies and directly held equity securities are valued at the closing price reported in the active market in which the securities are traded. Level 1 plan assets also include interest-bearing cash, which is held in money market accounts managed by an affiliate of the trustee and money market funds within their securities lending invested collateral.

Level 2 - Pricing inputs are quoted prices for similar asset or liabilities in active markets, quoted prices for identical or similar assets or liabilities in inactive markets, inputs other than quoted prices that are observable for the asset or liability and inputs that are derived principally from or corroborated by observable market data by correlation or other means. Alliant Energy's, IPL's and WPL's investments in corporate bonds and government and agency obligations are valued at the closing price reported in the active market for similar assets in which the individual securities are traded or based on yields currently available on comparable securities of issuers with similar credit ratings. Alliant Energy's, IPL's and WPL's investments in equity and fixed income securities in common/collective trusts are valued at the net asset value of shares held by the plans, which is based on the fair market value of the underlying investments in equity and fixed income securities of the common/collective trusts. Level 2 plan assets also consist of asset backed securities within their securities lending invested collateral.

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. Alliant Energy's, IPL's and WPL's Level 3 plan assets include certain asset backed securities and corporate bonds within their securities lending invested collateral.

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.

The methods described above may produce a fair value calculation that may not be indicative of net realizable value or reflective of future fair values. Furthermore, while Alliant Energy, IPL and WPL believe their valuation methods are appropriate and consistent with other market participants, the use of different methodologies or assumptions to determine the fair value of certain financial instruments could result in a different fair value measurement at the reporting date.

At Dec. 31, the fair values of Alliant Energy's qualified and non-qualified defined benefit pension plans assets by asset category and fair value hierarchy level were as follows (in millions):

Alliant Energy

	2011									2010
	Fair Value			Level 1		Level 2		Level 3		Fair Value			Level 1		Level 2		Level 3
Cash and equivalents	$	117.5		$	117.5	$	—	$	—	$	11.1		$	11.1	$	—	$	—
Equity securities:
U.S. large cap core		110.7			110.7		—		—		118.4			118.4		—		—
U.S. large cap value		91.6			—		91.6		—		100.4			—		100.4		—
U.S. large cap growth		91.5			—		91.5		—		101.0			—		101.0		—
U.S. small cap value		25.7			—		25.7		—		29.0			—		29.0		—
U.S. small cap growth		21.7			21.7		—		—		16.6			16.6		—		—
International - developed markets		126.4			65.4		61.0		—		142.3			76.0		66.3		—
International - emerging markets		30.4			30.4		—		—		34.1			34.1		—		—
Fixed income securities:
Corporate bonds		57.1			—		57.1		—		54.2			—		54.2		—
Government and agency obligations		87.8			—		87.8		—		78.9			—		78.9		—
Fixed income funds		146.7			0.2		146.5		—		142.7			0.2		142.5		—
Securities lending invested collateral		9.3			4.7		2.8		1.8		17.3			3.0		11.5		2.8
		916.4		$	350.6	$	564.0	$	1.8		846.0		$	259.4	$	583.8	$	2.8
Accrued investment income		1.0									1.2
Due to brokers, net (a)		(4.7	)								(0.6	)
Due to borrowers for securities lending program		(15.3	)								(23.6	)
Total pension plan assets	$	897.4								$	823.0

(a) This category represents pending trades with brokers.

At Dec. 31, the fair values of IPL's and WPL's qualified and non-qualified defined benefit pension plan assets associated with IPL's and WPL's current and former non-bargaining employees who are participants in Alliant Energy and Corporate Services sponsored plans that were directly assigned to IPL and WPL, along with the percentage these assets represent of the fair values by asset category and fair value hierarchy level shown in the above table were as follows (dollars in millions):

	IPL						WPL
	2011			2010			2011			2010
Fair values of directly assigned amounts	$	127.4		$	127.6		$	97.0		$	95.6
Percentage represented		14.2	%		15.5	%		10.8	%		11.6	%

At Dec. 31, the fair values of IPL's and WPL's qualified defined benefit pension plans assets by asset category and fair value hierarchy level were as follows (in millions):

IPL

	2011									2010
	Fair Value			Level 1		Level 2		Level 3		Fair Value			Level 1		Level 2		Level 3
Cash and equivalents	$	39.1		$	39.1	$	—	$	—	$	3.5		$	3.5	$	—	$	—
Equity securities:
U.S. large cap core		36.8			36.8		—		—		37.0			37.0		—		—
U.S. large cap value		30.5			—		30.5		—		31.4			—		31.4		—
U.S. large cap growth		30.5			—		30.5		—		31.5			—		31.5		—
U.S. small cap value		8.6			—		8.6		—		9.0			—		9.0		—
U.S. small cap growth		7.2			7.2		—		—		5.2			5.2		—		—
International - developed markets		42.1			21.8		20.3		—		44.4			23.7		20.7		—
International - emerging markets		10.1			10.1		—		—		10.7			10.7		—		—
Fixed income securities:
Corporate bonds		19.0			—		19.0		—		16.9			—		16.9		—
Government and agency obligations		29.2			—		29.2		—		24.6			—		24.6		—
Fixed income funds		48.8			0.1		48.7		—		44.5			—		44.5		—
Securities lending invested collateral		3.1			1.6		0.9		0.6		5.4			0.9		3.6		0.9
		305.0		$	116.7	$	187.7	$	0.6		264.1		$	81.0	$	182.2	$	0.9
Accrued investment income		0.4									0.4
Due to brokers, net (a)		(1.6	)								(0.2	)
Due to borrowers for securities lending program		(5.1	)								(7.4	)
Total pension plan assets	$	298.7								$	256.9

WPL

	2011									2010
	Fair Value			Level 1		Level 2		Level 3		Fair Value			Level 1		Level 2		Level 3
Cash and equivalents	$	37.9		$	37.9	$	—	$	—	$	3.4		$	3.4	$	—	$	—
Equity securities:
U.S. large cap core		35.7			35.7		—		—		36.7			36.7		—		—
U.S. large cap value		29.6			—		29.6		—		31.2			—		31.2		—
U.S. large cap growth		29.5			—		29.5		—		31.3			—		31.3		—
U.S. small cap value		8.3			—		8.3		—		9.0			—		9.0		—
U.S. small cap growth		7.0			7.0		—		—		5.2			5.2		—		—
International - developed markets		40.8			21.1		19.7		—		44.1			23.6		20.5		—
International - emerging markets		9.8			9.8		—		—		10.6			10.6		—		—
Fixed income securities:
Corporate bonds		18.4			—		18.4		—		16.8			—		16.8		—
Government and agency obligations		28.3			—		28.3		—		24.5			—		24.5		—
Fixed income funds		47.4			0.1		47.3		—		44.2			—		44.2		—
Securities lending invested collateral		3.0			1.5		0.9		0.6		5.4			1.0		3.5		0.9
		295.7		$	113.1	$	182.0	$	0.6		262.4		$	80.5	$	181.0	$	0.9
Accrued investment income		0.3									0.3
Due to brokers, net (a)		(1.5	)								(0.2	)
Due to borrowers for securities lending program		(4.9	)								(7.3	)
Total pension plan assets	$	289.6								$	255.2

(a) This category represents pending trades with brokers.

At Dec. 31, the fair values of Alliant Energy's, IPL's and WPL's other postretirement benefits plans assets by asset category and fair value hierarchy level were as follows (in millions):

Alliant Energy

	2011									2010
	Fair Value			Level 1		Level 2		Level 3		Fair Value			Level 1		Level 2		Level 3
Cash and equivalents	$	14.0		$	14.0	$	—	$	—	$	15.4		$	15.4	$	—	$	—
Equity securities:
U.S. large cap core		37.1			37.1		—		—		38.6			38.6		—		—
U.S. large cap value		2.4			—		2.4		—		2.7			—		2.7		—
U.S. large cap growth		2.4			—		2.4		—		2.7			—		2.7		—
U.S. mid cap core		17.8			17.8		—		—		18.6			18.6		—		—
U.S. small cap core		4.7			4.7		—		—		3.8			3.8		—		—
U.S. small cap value		0.6			—		0.6		—		0.8			—		0.8		—
U.S. small cap growth		0.5			0.5		—		—		0.4			0.4		—		—
International - developed markets		3.3			1.7		1.6		—		3.9			2.1		1.8		—
International - emerging markets		0.8			0.8		—		—		0.9			0.9		—		—
Fixed income securities:
Corporate bonds		6.1			—		6.1		—		6.3			—		6.3		—
Government and agency obligations		5.6			—		5.6		—		4.9			—		4.9		—
Fixed income funds		25.4			21.6		3.8		—		24.0			20.1		3.9		—
Securities lending invested collateral		0.4			0.2		0.1		0.1		0.8			0.2		0.5		0.1
		121.1		$	98.4	$	22.6	$	0.1		123.8		$	100.1	$	23.6	$	0.1
Accrued investment income		0.1									0.1
Due to brokers, net (a)		(0.2	)								(0.1	)
Due to borrowers for securities lending program		(0.6	)								(1.1	)
Total other postretirement benefits plan assets	$	120.4								$	122.7

IPL

	2011									2010
	Fair Value			Level 1		Level 2		Level 3		Fair Value			Level 1		Level 2		Level 3
Cash and equivalents	$	2.1		$	2.1	$	—	$	—	$	3.5		$	3.5	$	—	$	—
Equity securities:
U.S. large cap core		29.3			29.3		—		—		30.7			30.7		—		—
U.S. large cap value		0.8			—		0.8		—		1.0			—		1.0		—
U.S. large cap growth		0.8			—		0.8		—		1.0			—		1.0		—
U.S. mid cap core		14.7			14.7		—		—		15.3			15.3		—		—
U.S. small cap value		0.2			—		0.2		—		0.3			—		0.3		—
U.S. small cap growth		0.2			0.2		—		—		0.2			0.2		—		—
International - developed markets		1.2			0.6		0.6		—		1.4			0.8		0.6		—
International - emerging markets		0.3			0.3		—		—		0.3			0.3		—		—
Fixed income securities:
Corporate bonds		4.6			—		4.6		—		4.5			—		4.5		—
Government and agency obligations		4.1			—		4.1		—		3.3			—		3.3		—
Fixed income funds		16.5			15.1		1.4		—		16.0			14.6		1.4		—
Securities lending invested collateral		0.2			0.1		0.1		—		0.5			0.1		0.3		0.1
		75.0		$	62.4	$	12.6	$	—		78.0		$	65.5	$	12.4	$	0.1
Accrued investment income		0.1									0.2
Due to borrowers for securities lending program		(0.4	)								(0.7	)
Total other postretirement benefits plan assets	$	74.7								$	77.5

WPL

	2011									2010
	Fair Value			Level 1		Level 2		Level 3		Fair Value			Level 1		Level 2		Level 3
Cash and equivalents	$	10.5		$	10.5	$	—	$	—	$	10.7		$	10.7	$	—	$	—
Equity securities:
U.S. large cap core		1.2			1.2		—		—		1.3			1.3		—		—
U.S. large cap value		1.0			—		1.0		—		1.1			—		1.1		—
U.S. large cap growth		1.0			—		1.0		—		1.1			—		1.1		—
U.S. small cap core		4.7			4.7		—		—		3.8			3.8		—		—
U.S. small cap value		0.3			—		0.3		—		0.3			—		0.3		—
U.S. small cap growth		0.2			0.2		—		—		0.2			0.2		—		—
International - developed markets		1.3			0.7		0.6		—		1.6			0.8		0.8		—
International - emerging markets		0.3			0.3		—		—		0.4			0.4		—		—
Fixed income securities:
Corporate bonds		1.1			—		1.1		—		1.4			—		1.4		—
Government and agency obligations		1.0			—		1.0		—		1.0			—		1.0		—
Fixed income funds		2.6			1.0		1.6		—		2.3			0.7		1.6		—
Securities lending invested collateral		0.1			0.1		—		—		0.2			0.1		0.1		—
		25.3		$	18.7	$	6.6	$	—		25.4		$	18.0	$	7.4	$	—
Due to brokers, net (a)		(0.1	)								(0.1	)
Due to borrowers for securities lending program		(0.1	)								(0.3	)
Total other postretirement benefits plan assets	$	25.1								$	25.0

(a) This category represents pending trades with brokers.

For the various Alliant Energy defined benefit pension and other postretirement benefits plans, Alliant Energy common stock represented less than 1% of total plan assets at Dec. 31, 2011 and 2010.

Alliant Energy Cash Balance Plan - Alliant Energy's defined benefit pension plans include the Cash Balance Plan that provides benefits for certain non-bargaining unit employees. The Cash Balance Plan has been closed to new hires since 2005. Effective 2008, Alliant Energy amended the Cash Balance Plan by discontinuing additional contributions into employees' Cash Balance Plan accounts. Also effective 2008, Alliant Energy increased its level of contributions to its 401(k) Savings Plan, which offset the impact of discontinuing additional contributions into the employees' Cash Balance Plan accounts. In 2009, Alliant Energy amended the Cash Balance Plan by changing participants' future interest credit formula to use the annual change in the consumer price index as the interest credit. This amendment provides participants an interest crediting rate that is 3% more than the annual change in the consumer price index. Refer to Note 13(b) for discussion of a class action lawsuit filed against the Cash Balance Plan in 2008 and the IRS review of the tax qualified status of the Plan.

401(k) Savings Plans - A significant number of Alliant Energy, IPL and WPL employees participate in defined contribution retirement plans (401(k) savings plans). The number of employees participating in these plans has increased recently as certain bargaining unit employees have elected to participate in defined contribution retirement plans instead of defined benefit pension plans. In 2009, Alliant Energy, IPL and WPL implemented several cost saving initiatives to reduce operation and maintenance expenses, including suspension of a portion of 401(k) savings plans contributions during the second half of 2009. Alliant Energy common stock represented 14.6% and 12.9% of total assets held in 401(k) savings plans at Dec. 31, 2011 and 2010, respectively. Alliant Energy's, IPL's and WPL's costs related to the 401(k) savings plans, which are partially based on the participants' level of contribution, were as follows (in millions):

	Alliant Energy						IPL						WPL
	2011		2010		2009		2011		2010		2009		2011		2010		2009
401(k) savings plans costs	$	18.7	$	18.5	$	16.2	$	9.2	$	8.8	$	2.8	$	8.4	$	8.9	$	4.3

(b) Equity Incentive Plans - In 2010, Alliant Energy's shareowners approved the Alliant Energy 2010 Omnibus Incentive Plan (OIP), which permits the grant of stock options, restricted stock, restricted stock units, performance shares, performance units, and other stock-based awards and cash incentive awards to key employees. At Dec. 31, 2011, performance shares and restricted stock were outstanding and 4.3 million shares of Alliant Energy's common stock remained available for grants under the OIP. Upon shareowner approval of the OIP, the Alliant Energy 2002 Equity Incentive Plan (EIP) terminated resulting in no new awards authorized to be granted under the EIP. All awards previously granted under the EIP that are still outstanding remain valid and continue to be subject to all of the terms and conditions of the EIP. At Dec. 31, 2011, non-qualified stock options, restricted stock and performance shares were outstanding under the EIP and another predecessor plan under which new awards can no longer be granted. Alliant Energy satisfies payouts related to equity awards under the OIP and EIP through the issuance of new shares of its common stock. Alliant Energy also has the Alliant Energy Director Long Term Incentive Plan (DLIP), which permits the grant of long-term incentive awards, including performance units and restricted cash awards to certain key employees. At Dec. 31, 2011, performance units and performance contingent cash awards were outstanding under the DLIP. There is no limit to the number of grants that can be made under the DLIP and Alliant Energy satisfies all payouts under the DLIP through cash.

A summary of compensation expense and the related income tax benefits recognized for share-based compensation awards was as follows (in millions):

	Alliant Energy						IPL						WPL
	2011		2010		2009		2011		2010		2009		2011		2010		2009
Compensation expense	$	10.1	$	7.5	$	2.8	$	5.5	$	4.0	$	1.6	$	4.1	$	3.0	$	1.1
Income tax benefits		4.0		3.0		1.2		2.2		1.6		0.7		1.7		1.2		0.4

As of Dec. 31, 2011, total unrecognized compensation cost related to nonvested share-based compensation awards was $9.3 million, which is expected to be recognized over a weighted average period between one and two years. Share-based compensation expense is recognized on a straight-line basis over the requisite service periods and is primarily recorded in "Utility - other operation and maintenance" in the Consolidated Statements of Income.

Performance Shares and Units - Payouts of performance shares and units to key employees are contingent upon achievement over three-year periods of specified performance criteria, which currently include metrics of total shareowner return relative to investor-owned utility peer groups. Payouts of nonvested performance shares and units issued prior to 2012 are prorated at retirement, death, disability or involuntary termination without cause based on time worked during the performance period and achievement of the performance criteria. Participants' nonvested performance shares and units issued prior to 2012 are forfeited if the participant voluntarily leaves Alliant Energy or is terminated for cause. Nonvested performance shares and units do not have non-forfeitable rights to dividends when dividends are paid to common shareowners. Alliant Energy anticipates making future payouts of its performance shares and units in cash; therefore, performance shares and units are accounted for as liability awards.

Performance Shares - Performance shares can be paid out in shares of Alliant Energy's common stock, cash or a combination of cash and stock and are adjusted by a performance multiplier, which ranges from zero to 200% based on the performance criteria. A summary of the performance shares activity was as follows:

	2011			2010			2009
	Shares (a)			Shares (a)			Shares (a)
Nonvested shares, Jan. 1		234,518			256,579			208,579
Granted		64,217			72,487			152,735
Vested (b)		(57,838	)		—			(84,633	)
Forfeited (c)		(3,918	)		(94,548	)		(20,102	)
Nonvested shares, Dec. 31		236,979			234,518			256,579

(a) Share amounts represent the target number of performance shares. Each performance share's value is based on the price of one share of Alliant Energy's common stock at the end of the performance period. The actual number of shares that will be paid out upon vesting is dependent upon actual performance and may range from zero to 200% of the target number of shares.

(b) In 2011, 57,838 performance shares granted in 2008 vested at 75% of the target, resulting in a payout valued at $1.6 million, which consisted of a combination of cash and common stock (1,387 shares). In 2009, 84,633 performance shares granted in 2006 vested resulting in a payout valued at $4.1 million, which consisted of a combination of cash and common stock (51,189 shares).

(c) In 2010, 57,100 performance shares granted in 2007 were forfeited without payout because the specified performance criteria for such shares were not met. The remaining forfeitures during 2011, 2010 and 2009 were primarily caused by retirements and voluntary terminations of participants.

Performance Units - Alliant Energy granted share-based compensation awards to key employees in 2011 and 2010 referred to as performance units. The performance units and the performance contingent cash awards discussed below were granted in 2011 and 2010 in lieu of time-based restricted stock. Performance units must be paid out in cash and are adjusted by a performance multiplier, which ranges from zero to 200% based on the performance criteria. A summary of the performance unit activity was as follows:

	2011			2010
	Units (a)			Units (a)
Nonvested units, Jan. 1		23,128			—
Granted		23,975			23,795
Forfeited		(4,107	)		(667	)
Nonvested units, Dec. 31		42,996			23,128

(a) Unit amounts represent the target number of performance units. Each performance unit's value is based on the average price of one share of Alliant Energy's common stock on the grant date of the award. The actual payout for performance units is dependent upon actual performance and may range from zero to 200% of the target number of units.

Fair Value of Awards - Information related to fair values of nonvested performance shares and units at Dec. 31, 2011, by year of grant, were as follows:

	Performance Shares									Performance Units
	2011 Grant			2010 Grant			2009 Grant			2011 Grant			2010 Grant
Nonvested awards		62,170			62,829			111,980			22,279			20,717
Alliant Energy common stock closing price on Dec. 31, 2011	$	44.11		$	44.11		$	44.11
Alliant Energy common stock average price on grant date										$	38.75		$	32.56
Estimated payout percentage based on performance criteria		106	%		155	%		163	%		106	%		155	%
Fair values of each nonvested award	$	46.76		$	68.37		$	71.68		$	41.08		$	50.46

At Dec. 31, 2011, fair values of nonvested performance shares and units were calculated using a Monte Carlo simulation to determine the anticipated total shareowner returns of Alliant Energy and its investor-owned utility peer groups. Expected volatility was based on historical volatilities using daily stock prices over the past three years. Expected dividend yields were calculated based on the most recent quarterly dividend rates announced prior to the measurement date and stock prices at the measurement date. The risk-free interest rate was based on the three-year U.S. Treasury rate in effect as of the measurement date.

Restricted Stock - Restricted stock issued under the EIP consists of time-based and performance-contingent restricted stock.

Time-based Restricted Stock - The current restriction period for outstanding time-based restricted stock is up to three years. Nonvested shares of time-based restricted stock generally become vested upon retirement. Compensation costs related to awards granted to retirement-eligible employees are generally expensed on the date of grant. Participants' nonvested time-based restricted stock issued prior to 2012 is forfeited if the participant voluntarily leaves Alliant Energy or is terminated for cause. Nonvested time-based restricted stock issued prior to 2012 is fully vested in the event of retirement, death, disability or involuntary termination without cause. The fair value of time-based restricted stock is based on the average market price at the grant date. A summary of the time-based restricted stock activity was as follows:

	2011					2010					2009
	Shares			Weighted Average Fair Value		Shares			Weighted Average Fair Value		Shares			Weighted Average Fair Value
Nonvested shares, Jan. 1		70,033		$	32.27		125,349		$	32.47		156,807		$	32.80
Granted		5,000			39.86		—			—		51,236			29.40
Vested		(38,633	)		34.60		(54,016	)		32.72		(79,459	)		31.08
Forfeited		(600	)		29.41		(1,300	)		32.78		(3,235	)		33.97
Nonvested shares, Dec. 31		35,800			30.87		70,033			32.27		125,349			32.47

Performance-contingent Restricted Stock - Vesting of performance-contingent restricted stock grants are based on the achievement of certain performance targets (currently specified earnings growth). The performance metric for the 2011, 2010 and 2009 grants is consolidated net income growth. If performance targets are not met within the performance period, which currently ranges from two to four years, these restricted stock grants are forfeited. Nonvested shares of performance- contingent restricted stock issued prior to 2012 are prorated at retirement based on time worked during the performance period and vest only if and when the performance criteria are met. Participants' nonvested performance-contingent restricted stock issued prior to 2012 is forfeited if the participant voluntarily leaves Alliant Energy for reasons other than retirement. The fair value of performance-contingent restricted stock is based on the average market price at the grant date. A summary of the performance-contingent restricted stock activity was as follows:

	2011					2010					2009
	Shares			Weighted Average Fair Value		Shares			Weighted Average Fair Value		Shares		Weighted Average Fair Value
Nonvested shares, Jan. 1		296,190		$	32.32		226,007		$	32.25		124,185	$	39.28
Granted		64,217			38.75		72,487			32.56		101,822		23.67
Vested		(53,274	)		37.93		—			—		—		—
Forfeited		(5,395	)		38.00		(2,304	)		32.56		—		—
Nonvested shares, Dec. 31		301,738			32.60		296,190			32.32		226,007		32.25

Non-qualified Stock Options - Options granted under the plans were granted at the market price of the shares on the date of grant, vest over three years and expire no later than 10 years after the grant date. Options become fully vested upon retirement and remain exercisable at any time prior to their expiration date or for three years after the effective date of the retirement, whichever period is shorter. Options become fully vested upon death or disability and remain exercisable at any time prior to their expiration date or for one year after the effective date of the death or disability, whichever period is shorter. If participants leave Alliant Energy for reasons other than retirement, death or disability, their options that are not vested are forfeited and their vested options expire three months after their departure. Alliant Energy has not granted any options since 2004. A summary of the stock option activity was as follows:

	2011					2010					2009
	Shares			Weighted Average Exercise Price		Shares			Weighted Average Exercise Price		Shares			Weighted Average Exercise Price
Outstanding, Jan. 1		163,680		$	24.51		384,331		$	27.02		497,183		$	27.30
Exercised		(99,791	)		24.71		(191,433	)		28.93		(39,877	)		25.80
Expired		—			—		(29,218	)		28.59		(56,098	)		29.88
Forfeited		—			—		—			—		(16,877	)		28.67
Outstanding and exercisable, Dec. 31		63,889			24.21		163,680			24.51		384,331			27.02

The weighted average remaining contractual term for options outstanding and exercisable at Dec. 31, 2011 was between one and two years. The aggregate intrinsic value of options outstanding and exercisable at Dec. 31, 2011 was $1.3 million.

Other information related to stock option activity was as follows (in millions):

	2011		2010		2009
Cash received from stock options exercised	$	2.5	$	5.5	$	1.0
Aggregate intrinsic value of stock options exercised		1.6		1.1		0.1
Income tax benefit from the exercise of stock options		0.7		0.4		0.1

Performance Contingent Cash Awards - Alliant Energy granted share-based compensation awards to key employees in 2011 and 2010 referred to as performance contingent cash awards. Performance contingent cash award payouts to key employees are based on the achievement of certain performance targets (currently specified consolidated net income growth). If performance targets are not met within the performance period, which currently ranges from two to four years, there are no payouts for these awards. Nonvested awards issued prior to 2012 are prorated at retirement based on time worked during the performance period and achievement of the performance criteria. Participants' nonvested awards issued prior to 2012 are forfeited if the participant voluntarily leaves Alliant Energy for reasons other than retirement. Each performance contingent cash award's value is based on the price of one share of Alliant Energy's common stock at the end of the performance period. Alliant Energy accounts for performance contingent cash awards as liability awards because payouts will be made in the form of cash. A summary of the performance contingent cash awards activity was as follows:

	2011			2010
	Awards			Awards
Nonvested awards, Jan. 1		23,428			—
Granted		23,975			23,795
Forfeited		(727	)		(367	)
Nonvested awards, Dec. 31		46,676			23,428

(c) Deferred Compensation Plan - Alliant Energy maintains a deferred compensation plan under which key employees may defer up to 100% of base salary and incentive compensation and directors may elect to defer all or part of their retainer and committee fees. Key employees who have made the maximum allowed contribution to the Alliant Energy 401(k) Savings Plan may receive an additional credit to the deferred compensation plan. Key employees and directors may elect to have their deferrals credited to a company stock account, an interest account or equity accounts based on index funds.

Company Stock Accounts - The deferred compensation plan does not permit diversification of deferrals credited to the company stock account and all distributions from participants' company stock accounts are made in the form of shares of Alliant Energy common stock. The deferred compensation obligations for participants' company stock accounts are recorded in "Additional paid-in capital" and the shares of Alliant Energy common stock held in a rabbi trust to satisfy this obligation are recorded in "Shares in deferred compensation trust" on Alliant Energy's Consolidated Balance Sheets. At Dec. 31, the carrying value of the deferred compensation obligation for the company stock accounts and the shares in the deferred compensation trust based on the historical value of the shares of Alliant Energy common stock contributed to the rabbi trust, and the fair market value of the shares held in the rabbi trust were as follows (in millions):

	2011		2010
Carrying value	$	8.3	$	7.6
Fair market value		11.6		9.1

Interest and Equity Accounts - Distributions from participants' interest and equity accounts are in the form of cash payments. The deferred compensation obligations for participants' interest and equity accounts are recorded in "Pension and other benefit obligations" on Alliant Energy's and IPL's Consolidated Balance Sheets. At Dec. 31, the carrying value of Alliant Energy's and IPL's deferred compensation obligations for participants' interest and equity accounts was as follows (in millions):

	Alliant Energy				IPL
	2011		2010		2011		2010
Carrying value	$	20.5	$	20.5	$	5.0	$	5.2

WPL [Member]

Benefit Plans

(6) BENEFIT PLANS

(a) Pension and Other Postretirement Benefits Plans - Alliant Energy, IPL and WPL provide retirement benefits to substantially all of their employees through various qualified and non-qualified non-contributory defined benefit pension plans, and through defined contribution plans (including 401(k) savings plans). Alliant Energy's, IPL's and WPL's qualified and non-qualified non-contributory defined benefit pension plans are currently closed to new hires. Benefits of the non-contributory defined benefit pension plans are based on the plan participant's years of service, age and compensation. Benefits of the defined contribution plans are based on the plan participant's years of service, age, compensation and contributions. Alliant Energy, IPL and WPL also provide certain defined benefit postretirement health care and life benefits to eligible retirees. In general, the retiree health care plans consist of fixed benefit subsidy structures and the retiree life insurance plans are non-contributory.

Assumptions - The assumptions for Alliant Energy's, IPL's and WPL's defined benefit pension and other postretirement benefits plans at the measurement date of Dec. 31 were as follows (Not Applicable (N/A)):

Alliant Energy

	Defined Benefit Pension Plans			Other Postretirement Benefits Plans
	2011	2010	2009	2011	2010	2009
Discount rate for benefit obligations	4.86%	5.56%	5.8%	4.6%	5.25%	5.55%
Discount rate for net periodic cost	5.56%	5.8%	6.15%	5.25%	5.55%	6.15%
Expected rate of return on plan assets	7.9%	8%	8.25%	7%	6.9%	8.25%
Rate of compensation increase	3.5-4.5%	3.5-4.5%	3.5-4.5%	3.5%	3.5%	3.5%
Medical cost trend on covered charges:
Initial trend rate (end of year)	N/A	N/A	N/A	8%	7%	7.5%
Ultimate trend rate	N/A	N/A	N/A	5%	5%	5%
IPL
	Qualified Defined Benefit Pension Plans			Other Postretirement Benefits Plans
	2011	2010	2009	2011	2010	2009
Discount rate for benefit obligations	4.95%	5.7%	5.8%	4.6%	5.25%	5.55%
Discount rate for net periodic cost	5.7%	5.8%	6.15%	5.25%	5.55%	6.15%
Expected rate of return on plan assets	7.9%	8%	8.25%	7.3%	7.1%	8.25%
Rate of compensation increase	3.5%	3.5%	3.5%	3.5%	3.5%	3.5%
Medical cost trend on covered charges:
Initial trend rate (end of year)	N/A	N/A	N/A	8%	7%	7.5%
Ultimate trend rate	N/A	N/A	N/A	5%	5%	5%

WPL

	Qualified Defined Benefit Pension Plans			Other Postretirement Benefits Plans
	2011	2010	2009	2011	2010	2009
Discount rate for benefit obligations	4.95%	5.7%	5.8%	4.6%	5.25%	5.55%
Discount rate for net periodic cost	5.7%	5.8%	6.15%	5.25%	5.55%	6.15%
Expected rate of return on plan assets	7.9%	8%	8.25%	6.3%	6.3%	8.25%
Rate of compensation increase	3.5%	3.5%	3.5%	3.5%	3.5%	3.5%
Medical cost trend on covered charges:
Initial trend rate (end of year)	N/A	N/A	N/A	8%	7%	7.5%
Ultimate trend rate	N/A	N/A	N/A	5%	5%	5%

Expected rate of return on plan assets - The expected rate of return on plan assets is determined by analysis of projected asset class returns based on the target asset class allocations. Alliant Energy uses a portfolio return simulator and also reviews historical returns, survey information and capital market information to support the expected rate of return on plan assets assumption. Refer to "Investment Policy and Strategy for Plan Assets" below for additional information related to Alliant Energy's investment policy and strategy and mix of assets for the pension and other postretirement benefits plans.

Medical cost trend on covered charges - The assumed medical trend rates are critical assumptions in determining the service and interest cost and accumulated postretirement benefit obligation related to postretirement benefits costs. A 1% change in the medical trend rates for 2011, holding all other assumptions constant, would have the following effects (in millions):

	Alliant Energy					IPL					WPL
	1% Increase		1% Decrease			1% Increase		1% Decrease			1% Increase		1% Decrease
Effect on total of service and interest cost components	$	0.5		($0.4	)	$	0.2		($0.2	)	$	0.2		($0.2	)
Effect on postretirement benefit obligation		2.9		(2.8	)		1.3		(1.2	)		1.5		(1.4	)

Net Periodic Benefit Costs - In the "IPL" and "WPL" tables below, the qualified defined benefit pension plans costs represent only those respective costs for bargaining unit employees of IPL and WPL covered under the plans that are sponsored by IPL and WPL, respectively. Also in the "IPL" and "WPL" tables, the other postretirement benefits costs represent costs for all IPL and WPL employees, respectively. The "Directly assigned defined benefit pension plans" tables include amounts directly assigned to each of IPL and WPL related to IPL's and WPL's current and former non-bargaining employees who are participants in Alliant Energy and Corporate Services sponsored qualified and non-qualified defined benefit pension plans. The components of Alliant Energy's, IPL's and WPL's net periodic benefit costs for their sponsored defined benefit pension and other postretirement benefits plans, and defined benefit pension plans amounts directly assigned to IPL and WPL,as recognized on Alliant Energy's, IPL's and WPL's Consolidated Statements of Income, were as follows (in millions):

Alliant Energy

	Defined Benefit Pension Plans									Other Postretirement Benefits Plans (a)
	2011			2010			2009			2011			2010			2009
Service cost	$	11.4		$	11.9		$	11.9		$	7.0		$	9.3		$	8.7
Interest cost		52.0			52.3			54.3			12.3			14.9			15.2
Expected return on plan assets (b)		(63.8	)		(62.1	)		(47.6	)		(7.9	)		(7.7	)		(6.1	)
Amortization of (c):
Transition obligation		—			—			—			—			0.1			0.2
Prior service cost (credit)		0.7			0.9			2.1			(10.0	)		(2.4	)		(3.7	)
Actuarial loss		21.1			23.8			30.6			5.3			7.4			6.2
Additional benefit costs (d)		10.2			—			—			—			—			—
Settlement losses (e)		1.1			1.4			—			—			—			—
Curtailment losses (f)(g)		—			—			1.0			—			—			—
Special termination benefits costs (g)		—			—			0.9			—			—			—
	$	32.7		$	28.2		$	53.2		$	6.7		$	21.6		$	20.5

IPL

	Qualified Defined Benefit Pension Plans									Other Postretirement Benefits Plans (a)
	2011			2010			2009			2011			2010			2009
Service cost	$	6.1		$	6.2		$	6.1		$	2.6		$	3.4		$	3.1
Interest cost		16.7			16.5			16.1			5.5			6.8			7.3
Expected return on plan assets (b)		(20.0	)		(19.5	)		(14.0	)		(5.4	)		(5.3	)		(4.2	)
Amortization of (c):
Transition obligation		—			—			—			—			0.1			0.2
Prior service cost (credit)		0.5			0.6			0.8			(5.0	)		(1.1	)		(1.6	)
Actuarial loss		5.7			7.2			9.3			2.9			4.0			4.0
	$	9.0		$	11.0		$	18.3		$	0.6		$	7.9		$	8.8
WPL
	Qualified Defined Benefit Pension Plan									Other Postretirement Benefits Plans (a)
	2011			2010			2009			2011			2010			2009
Service cost	$	4.5		$	4.9		$	4.9		$	2.9		$	3.6		$	3.4
Interest cost		16.1			15.7			15.5			4.9			5.5			5.5
Expected return on plan assets (b)		(20.0	)		(19.1	)		(14.1	)		(1.3	)		(1.3	)		(1.1	)
Amortization of (c):
Prior service cost (credit)		0.5			0.5			0.5			(3.4	)		(0.7	)		(0.9	)
Actuarial loss		7.1			8.5			10.4			2.1			2.5			1.3
Curtailment loss (f)		—			—			0.7			—			—			—
Special termination benefits costs (g)		—			—			0.9			—			—			—
	$	8.2		$	10.5		$	18.8		$	5.2		$	9.6		$	8.2
Directly assigned defined benefit pension plans	IPL									WPL
	2011			2010			2009			2011			2010			2009
Interest cost	$	7.3		$	7.8		$	8.7		$	5.5		$	5.6		$	6.1
Expected return on plan assets (b)		(9.7	)		(9.7	)		(8.4	)		(7.3	)		(7.3	)		(6.3	)
Amortization of (c):
Prior service credit		(0.2	)		(0.3	)		(0.1	)		(0.2	)		(0.2	)		—
Actuarial loss		3.0			2.9			4.2			3.0			2.8			3.6
Additional benefit costs (d)		2.8			—			—			0.7			—			—
Curtailment gain		—			—			(0.1	)		—			—			—
	$	3.2		$	0.7		$	4.3		$	1.7		$	0.9		$	3.4

(a) In May 2011, Alliant Energy, IPL and WPL amended their defined benefit postretirement health care plans resulting in a revision to the method and level of coverage provided for participants more than 65 years of age. This amendment was determined to be a significant event, which required Alliant Energy, IPL and WPL to remeasure their defined benefit postretirement health care plans in May 2011. The amendment resulted in a decrease in Alliant Energy's, IPL's and WPL's postretirement benefit obligations of $55 million, $30 million and $16 million, respectively, in 2011 with the impact of the remeasurement on net periodic benefit costs being recognized prospectively from the remeasurement date. The impact of the remeasurement decreased Alliant Energy's, IPL's and WPL's net periodic benefit costs by $11.3 million, $7.2 million, and $3.8 million in 2011, respectively. The discount rate used for the remeasurement was 5.20%. All other assumptions used for the remeasurement were consistent with the measurement assumptions used at Dec. 31, 2010.

(b) The expected return on plan assets is based on the expected rate of return on plan assets and the fair value approach to the market-related value of plan assets.

(c) Unrecognized net actuarial gains or losses in excess of 10% of the greater of the plans' benefit obligation or asset are amortized over the average future service lives of plan participants, except for the Alliant Energy Cash Balance Pension Plan (Cash Balance Plan) where gains or losses outside the 10% threshold are amortized over the time period the participants are expected to receive benefits. Unrecognized prior service costs (credits) for the postretirement benefits plans are amortized over the average future service period to full eligibility of the participants of each plan.

(d) Alliant Energy reached an agreement with the IRS, which resulted in a favorable determination letter for the Cash Balance Plan in 2011. The agreement with the IRS required Alliant Energy to amend the Cash Balance Plan, which was completed in 2011 resulting in aggregate additional benefits of $10.2 million paid to certain former participants in the Cash Balance Plan in 2011. Alliant Energy recognized $10.2 million ($6.3 million at IPL ($2.8 million directly assigned and $3.5 million allocated by Corporate Services) and $3.4 million at WPL ($0.7 million directly assigned and $2.7 million allocated by Corporate Services)) of additional benefits costs in 2011 related to these benefits. Refer to Note 13(b) for additional information regarding the Cash Balance Plan.

(e) In 2011 and 2010, the settlement losses of $1.1 million and $1.4 million, respectively, related to payments made to retired executives of Alliant Energy.

(f) In 2007, members of the International Brotherhood of Electrical Workers Local 965 ratified a four-year collective bargaining agreement reached with WPL, resulting in changes to WPL's qualified pension plan. One of these changes provided WPL qualified pension plan participants an option to cease participating in the WPL qualified pension plan and begin participating in the Alliant Energy 401(k) Savings Plan with increased levels of contribution by Alliant Energy. The election of this option did not impact a participant's eligibility for benefits previously vested under the WPL qualified pension plan. In 2009, certain of these employees elected to cease participating in the WPL qualified pension plan, resulting in Alliant Energy and WPL recognizing a curtailment loss related to the WPL qualified pension plan of $0.7 million in 2009.

(g) In 2009, Alliant Energy eliminated certain corporate and operations positions. As a result, Alliant Energy recognized curtailment losses related to its pension plans of $0.3 million in 2009. In addition, Alliant Energy and WPL recognized special termination benefits costs related to the qualified defined benefit pension plan that is sponsored by WPL of $0.9 million in 2009.

Corporate Services provides services to IPL and WPL, and as a result, IPL and WPL are allocated pension and other postretirement benefits costs associated with Corporate Services employees. The following table includes the allocated qualified and non-qualified pension and other postretirement benefits costs associated with Corporate Services employees providing services to IPL and WPL (in millions):

	Pension Benefits Costs (a)						Other Postretirement Benefits Costs
	2011		2010		2009		2011		2010		2009
IPL	$	5.8	$	2.9	$	5.1	$	0.3	$	2.0	$	1.8
WPL		4.2		1.9		3.2		0.2		1.3		1.2

(a) In 2011, additional qualified pension benefits costs resulting from the 2011 amendment to the Cash Balance Plan allocated to IPL and WPL by Corporate Services were $3.5 million and $2.7 million, respectively.

The estimated amortization from "Regulatory assets" and "Regulatory liabilities" on the Consolidated Balance Sheets and "Accumulated other comprehensive loss" (AOCL) on Alliant Energy's Consolidated Balance Sheet into net periodic benefit cost in 2012 is as follows (in millions):

	Alliant Energy					IPL					WPL
	Defined Benefit Pension Plans		Other Postretirement Benefits Plans			Qualified Defined Benefit Pension Plans		Other Postretirement Benefits Plans			Qualified Defined Benefit Pension Plans		Other Postretirement Benefits Plans
Actuarial loss	$	33.2	$	6.3		$	10.2	$	3.6		$	12.1	$	2.3
Prior service cost (credit)		0.3		(12.0	)		0.4		(6.3	)		0.5		(3.9	)
	$	33.5		($5.7	)	$	10.6		($2.7	)	$	12.6		($1.6	)

Directly assigned defined benefit pension plans	IPL			WPL
Actuarial loss	$	3.9		$	3.6
Prior service credit		(0.2	)		(0.1	)
	$	3.7		$	3.5

In addition to the estimated amortizations from "Regulatory assets" in the above tables for IPL and WPL, $1.9 million and $1.2 million, respectively, of amortizations are expected in 2012 from "Regulatory assets" associated with Corporate Services employees participating in other Alliant Energy sponsored plans allocated to IPL and WPL.

Alliant Energy's, IPL's and WPL's net periodic benefit costs are primarily included in "Utility - other operation and maintenance" in the Consolidated Statements of Income.

Benefit Plan Assets and Obligations - A reconciliation of the funded status of Alliant Energy's qualified and non-qualified defined benefit pension and other postretirement benefits plans to the amounts recognized on Alliant Energy's Consolidated Balance Sheets at Dec. 31 was as follows (in millions):

Alliant Energy

	Defined Benefit Pension Plans						Other Postretirement Benefits Plans
	2011			2010			2011			2010
Change in projected benefit obligation:
Net projected benefit obligation at Jan. 1	$	953.0		$	920.1		$	274.9		$	268.4
Service cost		11.4			11.9			7.0			9.3
Interest cost		52.0			52.3			12.3			14.9
Plan participants' contributions		—			—			6.4			5.6
Plan amendments (a)		10.2			—			(56.6	)		(3.1	)
Actuarial (gain) loss		126.2			27.0			(0.8	)		(0.2	)
Early Retiree Reinsurance Program (ERRP) proceeds		—			—			0.6			—
Gross benefits paid		(71.4	)		(58.3	)		(20.8	)		(21.2	)
Federal subsidy on other postretirement benefits paid		—			—			1.2			1.2
Net projected benefit obligation at Dec. 31		1,081.4			953.0			224.2			274.9
Change in plan assets:
Fair value of plan assets at Jan. 1		823.0			776.4			122.7			102.4
Actual return on plan assets		28.9			96.9			2.6			14.0
Employer contributions		116.9			8.0			9.5			21.9
Plan participants' contributions		—			—			6.4			5.6
Gross benefits paid		(71.4	)		(58.3	)		(20.8	)		(21.2	)
Fair value of plan assets at Dec. 31		897.4			823.0			120.4			122.7
Under funded status at Dec. 31		($184.0	)		($130.0	)		($103.8	)		($152.2	)
Amounts recognized on the Consolidated Balance Sheets consist of:
Non-current assets	$	—		$	—		$	1.3		$	—
Other current liabilities		(4.6	)		(6.9	)		—			—
Pension and other benefit obligations		(179.4	)		(123.1	)		(105.1	)		(152.2	)
Net amount recognized at Dec. 31		($184.0	)		($130.0	)		($103.8	)		($152.2	)

Amounts recognized in Regulatory Assets, Regulatory Liabilities and AOCL consist of (b):
Net actuarial loss	$	494.8		$	356.0		$	76.7		$	77.1
Prior service credit		(6.9	)		(6.2	)		(52.5	)		(5.7	)
	$	487.9		$	349.8		$	24.2		$	71.4

(a) Refer to "Net Periodic Benefit Costs" above for additional information regarding plan amendments to the defined benefit pension and other postretirement benefits plans in 2011.

(b) Refer to Note 1(b) and Alliant Energy's Consolidated Statements of Common Equity for amounts recognized in "Regulatory assets" and "AOCL," respectively, on Alliant Energy's Consolidated Balance Sheets. At Dec. 31, 2011, $3.3 million of regulatory liabilities were recognized related to Alliant Energy's other postretirement benefits plans.

A reconciliation of the funded status of IPL's and WPL's sponsored qualified defined benefit pension and other postretirement benefits plans to the amounts recognized on IPL's and WPL's Consolidated Balance Sheets, at Dec. 31 was as follows (in millions):

IPL

	Qualified Defined Benefit Pension Plans						Other Postretirement Benefits Plans
	2011			2010			2011			2010
Change in projected benefit obligation:
Net projected benefit obligation at Jan. 1	$	293.8		$	284.3		$	128.5		$	123.9
Service cost		6.1			6.2			2.6			3.4
Interest cost		16.7			16.5			5.5			6.8
Plan participants' contributions		—			—			2.0			1.6
Plan amendments (a)		—			—			(30.1	)		(1.7	)
Actuarial (gain) loss		45.2			3.1			(2.7	)		4.0
ERRP proceeds		—			—			0.2			—
Gross benefits paid		(17.3	)		(16.3	)		(9.1	)		(10.1	)
Federal subsidy on other postretirement benefits paid		—			—			0.6			0.6
Net projected benefit obligation at Dec. 31		344.5			293.8			97.5			128.5
Change in plan assets:
Fair value of plan assets at Jan. 1		256.9			242.8			77.5			68.4
Actual return on plan assets		9.1			30.4			1.4			9.6
Employer contributions		50.0			—			2.9			8.0
Plan participants' contributions		—			—			2.0			1.6
Gross benefits paid		(17.3	)		(16.3	)		(9.1	)		(10.1	)
Fair value of plan assets at Dec. 31		298.7			256.9			74.7			77.5
Under funded status at Dec. 31		($45.8	)		($36.9	)		($22.8	)		($51.0	)
Amounts recognized on the Consolidated Balance Sheets consist of:

Pension and other benefit obligations		($45.8	)		($36.9	)		($22.8	)		($51.0	)
Amounts recognized in Regulatory Assets and Regulatory Liabilities consist of (b):
Net actuarial loss	$	141.1		$	90.8		$	41.0		$	42.4
Prior service cost (credit)		1.1			1.6			(27.6	)		(2.5	)
	$	142.2		$	92.4		$	13.4		$	39.9

WPL

	Qualified Defined Benefit Pension Plan						Other Postretirement Benefits Plans
	2011			2010			2011			2010
Change in projected benefit obligation:
Net projected benefit obligation at Jan. 1	$	283.3		$	271.6		$	103.3		$	99.1
Service cost		4.5			4.9			2.9			3.6
Interest cost		16.1			15.7			4.9			5.5
Plan participants' contributions		—			—			3.3			3.2
Plan amendments (a)		—			—			(18.2	)		(1.5	)
Actuarial loss		43.3			2.5			2.3			1.9
ERRP proceeds		—			—			0.2			—
Gross benefits paid		(14.7	)		(11.4	)		(9.6	)		(9.0	)
Federal subsidy on other postretirement benefits paid		—			—			0.5			0.5
Net projected benefit obligation at Dec. 31		332.5			283.3			89.6			103.3
Change in plan assets:
Fair value of plan assets at Jan. 1		255.2			236.6			25.0			18.8
Actual return on plan assets		9.1			30.0			0.9			2.1
Employer contributions		40.0			—			5.5			9.9
Plan participants' contributions		—			—			3.3			3.2
Gross benefits paid		(14.7	)		(11.4	)		(9.6	)		(9.0	)
Fair value of plan assets at Dec. 31		289.6			255.2			25.1			25.0
Under funded status at Dec. 31		($42.9	)		($28.1	)		($64.5	)		($78.3	)

WPL

	Qualified Defined Benefit Pension Plan						Other Postretirement Benefits Plans
	2011			2010			2011			2010
Amounts recognized on the Consolidated Balance Sheets consist of:
Non-current asset	$	—		$	—		$	1.3		$	—
Pension and other benefit obligations		(42.9	)		(28.1	)		(65.8	)		(78.3	)
Net amount recognized at Dec. 31		($42.9	)		($28.1	)		($64.5	)		($78.3	)
Amounts recognized in Regulatory Assets:
Net actuarial loss	$	142.7		$	95.6		$	27.8		$	27.2
Prior service cost (credit)		2.4			2.9			(17.3	)		(2.5	)
	$	145.1		$	98.5		$	10.5		$	24.7

(a) Refer to "Net Periodic Benefit Costs" above for additional information regarding plan amendments to the defined benefit pension and other postretirement benefits plans in 2011.

(b) At Dec. 31, 2011, $2.8 million of regulatory liabilities were recognized related to IPL's other postretirement benefits plans.

Included in the following tables are Alliant Energy's, IPL's and WPL's accumulated benefit obligations, aggregate amounts applicable to defined benefit pension and other postretirement benefits plans with accumulated benefit obligations in excess of plan assets, as well as defined benefit pension plans with projected benefit obligations in excess of plan assets as of the Dec. 31 measurement date (Not Applicable (N/A); in millions):

Alliant Energy

	Defined Benefit Pension Plans				Other Postretirement Benefits Plans
	2011		2010		2011		2010
Accumulated benefit obligations	$	1,029.4	$	915.5	$	224.2	$	274.9
Plans with accumulated benefit obligations in excess of plan assets:
Accumulated benefit obligations		1,029.4		915.5		224.2		274.9
Fair value of plan assets		897.4		823.0		120.4		122.7
Plans with projected benefit obligations in excess of plan assets:
Projected benefit obligations		1,081.4		953.0		N/A		N/A
Fair value of plan assets		897.4		823.0		N/A		N/A

IPL

	Qualified Defined Benefit Pension Plans				Other Postretirement Benefits Plans
	2011		2010		2011		2010
Accumulated benefit obligations	$	314.6	$	274.1	$	97.5	$	128.5
Plans with accumulated benefit obligations in excess of plan assets:
Accumulated benefit obligations		314.6		274.1		97.5		128.5
Fair value of plan assets		298.7		256.9		74.7		77.5
Plans with projected benefit obligations in excess of plan assets:
Projected benefit obligations		344.5		293.8		N/A		N/A
Fair value of plan assets		298.7		256.9		N/A		N/A

WPL

	Qualified Defined Benefit Pension Plans				Other Postretirement Benefits Plans
	2011		2010		2011		2010
Accumulated benefit obligations	$	314.7	$	270.2	$	89.6	$	103.3
Plans with accumulated benefit obligations in excess of plan assets:
Accumulated benefit obligations		314.7		270.2		89.6		103.3
Fair value of plan assets		289.6		255.2		25.1		25.0
Plans with projected benefit obligations in excess of plan assets:
Projected benefit obligations		332.5		283.3		N/A		N/A
Fair value of plan assets		289.6		255.2		N/A		N/A

The "Directly assigned defined benefit pension plans" table below includes amounts directly assigned to each of IPL and WPL related to IPL's and WPL's current and former non-bargaining employees who are participants in Alliant Energy and Corporate Services sponsored qualified and non-qualified defined benefit pension plans. A reconciliation of the funded status of the directly assigned qualified and non-qualified defined benefit pension plans to the amounts recognized on IPL's and WPL's Consolidated Balance Sheets at Dec. 31 was as follows (in millions):

Directly assigned defined benefit pension plans

	IPL						WPL
	2011			2010			2011			2010
Change in projected benefit obligation:
Net projected benefit obligation at Jan. 1	$	144.4		$	138.8		$	107.4		$	100.9
Interest cost		7.3			7.8			5.5			5.6
Plan amendments		2.8			—			0.7			—
Actuarial loss		13.2			8.0			10.3			8.7
Gross benefits paid		(12.3	)		(10.2	)		(8.7	)		(7.8	)
Net projected benefit obligation at Dec. 31		155.4			144.4			115.2			107.4
Change in plan assets:
Fair value of plan assets at Jan. 1		127.6			121.6			95.6			92.0
Actual return on plan assets		4.2			15.1			3.2			11.2
Employer contributions		7.9			1.1			6.9			0.2
Gross benefits paid		(12.3	)		(10.2	)		(8.7	)		(7.8	)
Fair value of plan assets at Dec. 31		127.4			127.6			97.0			95.6
Under funded status at Dec. 31		($28.0	)		($16.8	)		($18.2	)		($11.8	)
Amounts recognized on the Consolidated Balance Sheets consist of:
Other current liabilities		($0.8	)		($1.0	)		($0.2	)		($0.1	)
Pension and other benefit obligations		(27.2	)		(15.8	)		(18.0	)		(11.7	)
Net amount recognized at Dec. 31		($28.0	)		($16.8	)		($18.2	)		($11.8	)
Amounts recognized in Regulatory Assets:
Net actuarial loss	$	76.2		$	60.5		$	73.7		$	62.3
Prior service credit		(3.4	)		(3.6	)		(2.4	)		(2.6	)
	$	72.8		$	56.9		$	71.3		$	59.7
Accumulated benefit obligations	$	155.4		$	144.4		$	115.2		$	107.4

In addition to the amounts recognized in "Regulatory assets and regulatory liabilities" in the above tables for IPL and WPL, "Regulatory assets" and "Regulatory liabilities" were recognized for amounts associated with Corporate Services employees participating in other Alliant Energy sponsored benefit plans that were allocated to IPL and WPL at Dec. 31 as follows (in millions):

	IPL				WPL
	2011		2010		2011		2010
Regulatory assets	$	33.7	$	28.2	$	22.3	$	18.6
Regulatory liabilities		0.3		—		0.2		—

Estimated Future Employer Contributions and Benefit Payments - Alliant Energy, IPL, and WPL estimate that funding for the qualified defined benefit pension, non-qualified defined benefit pension and other postretirement benefits plans, and the directly assigned qualified and non-qualified defined benefit pension plans amounts, during 2012 will be as follows (in millions):

	Alliant Energy		IPL			WPL
Qualified defined benefit pension plans		$—	$	—		$	—
Non-qualified defined benefit pension plans		17.0			(a)			(a)
Directly assigned defined benefit pension plans (b)		N/A		0.8			0.2
Other postretirement benefits plans		4.9		0.6			3.9

(a) Alliant Energy sponsors several non-qualified defined benefit pension plans that cover certain current and former key employees of IPL and WPL. Alliant Energy allocates pension costs to IPL and WPL for these plans.

(b) Amounts directly assigned to IPL and WPL for non-bargaining employees who are participants in Alliant Energy and Corporate Services sponsored qualified and non-qualified defined benefit pension plans.

Alliant Energy's, IPL's and WPL's expected benefit payments, and the directly assigned qualified and non-qualified defined benefit pension benefits amounts, which reflect expected future service, as appropriate, are as follows (in millions):

Alliant Energy

	2012		2013		2014		2015		2016		2017 - 2021
Qualified and non-qualified defined benefit pension benefits	$	58.8	$	59.1	$	62.3	$	66.3	$	65.2	$	355.4
Other postretirement benefits		18.0		18.1		18.4		17.1		17.3		88.7
	$	76.8	$	77.2	$	80.7	$	83.4	$	82.5	$	444.1
IPL
	2012		2013		2014		2015		2016		2017 - 2021
Qualified defined benefit pension benefits	$	15.5	$	16.2	$	17.1	$	18.2		19.2	$	111.6
Directly assigned defined benefit pension benefits		12.1		11.4		12.3		13.0		11.0		57.0
Other postretirement benefits		8.9		8.7		8.6		7.4		7.4		37.0
	$	36.5	$	36.3	$	38.0	$	38.6	$	37.6	$	205.6
WPL
	2012		2013		2014		2015		2016		2017 - 2021
Qualified defined benefit pension benefits	$	13.0	$	13.8	$	14.9	$	15.9	$	17.0	$	103.3
Directly assigned defined benefit pension benefits		9.0		9.4		9.5		9.5		9.2		40.9
Other postretirement benefits		6.8		7.0		7.2		7.1		7.3		37.4
	$	28.8	$	30.2	$	31.6	$	32.5	$	33.5	$	181.6

Investment Policy and Strategy for Plan Assets - Alliant Energy's, IPL's and WPL's investment strategy and their policies employed with respect to assets of defined benefit pension and other postretirement benefits plans are to combine both preservation of principal and prudent and reasonable risk-taking to protect the integrity of plan assets, in order to meet the obligations to plan participants while minimizing benefit costs over the long term. It is recognized that risk and volatility are present with all types of investments. However, high levels of risk are mitigated at the total fund level through diversification by asset class including both U.S. and international equity exposure, the number of individual investments, and sector and industry limits when applicable. Alliant Energy, IPL and WPL also use an overlay management service to help maintain target allocations, liquidity needs and intended exposures to the plan assets. The overlay manager is authorized to use derivative financial instruments to facilitate this service.

Defined Benefit Pension Plans Assets - For assets of defined benefit pension plans, the mix among asset classes is controlled by long-term asset allocation targets. The assets are viewed as long-term with moderate liquidity needs. Historical performance results and future expectations suggest that equity securities will provide higher total investment returns than debt securities over a long-term investment horizon. Consistent with the goals of meeting obligations to plan participants and minimizing benefit costs over the long-term, the defined benefit pension plans have a long-term investment posture more heavily weighted towards equity holdings. The asset allocation mix is monitored regularly and appropriate steps are taken as needed to rebalance the assets within the prescribed range. Prohibited investment vehicles include, but may not be limited to, direct ownership of real estate, options and futures (unless specifically approved as is the case of the overlay manager), margin trading, oil and gas limited partnerships, commodities, short selling and securities of the managers' firms or affiliate firms. At Dec. 31, 2011, the current target range and actual allocations for Alliant Energy's, IPL's and WPL's defined benefit pension plan assets were as follows:

	Target Range	Actual
	Allocation	Allocation
Cash and equivalents (a)	0%-5%		13	%
Equity securities:
U.S. large cap core	10%-20%		12	%
U.S. large cap value	8%-16%		10	%
U.S. large cap growth	8%-16%		10	%
U.S. small cap value	0%-6%		3	%
U.S. small cap growth	0%-4%		2	%
International - developed markets	12%-24%		14	%
International - emerging markets	0%-8%		4	%
Fixed income securities	20%-40%		32	%

(a) Pension contributions of $100 million were made in late December 2011 and were invested in equity futures.

Other Postretirement Benefits Plans Assets - Other postretirement benefits plans assets are comprised of specific assets within certain defined benefit pension plans (401(h) assets) as well as assets held in Voluntary Employees' Beneficiary Association (VEBA) trusts. The investment policy and strategy of the 401(h) assets mirrors those of the defined benefit pension plans, which are discussed above. A mix of both equity and debt securities are utilized to maximize returns and mitigate risk over the long-term. There are no specific target allocations for the VEBA trusts as a whole. Separate investment guidelines have been established for the VEBA trusts which are actively managed. At Dec. 31, 2011, Alliant Energy's, IPL's and WPL's other postretirement benefits plan assets consisted of the following:

	Alliant Energy			IPL			WPL
Equity securities		58	%		63	%		39	%
Fixed income securities		31	%		34	%		19	%
Cash and equivalents		11	%		3	%		42	%

Securities Lending Program - Alliant Energy, IPL and WPL have a securities lending program with a third-party agent that allows the agent to lend certain securities from their defined benefit pension and other postretirement benefits plans to selected entities against receipt of collateral (in the form of cash, government and agency securities or letters of credit) as provided for and determined in accordance with its securities lending agency agreement. Initial collateral levels are no less than 100% of the market value of loans to non-affiliated borrowers of U.S. government securities; 102% of the market value of loans to affiliated borrowers of U.S. government securities; 102% of the market value of loans on U.S. corporate bonds and U.S. equity securities; 105% of the market value of loans on non-U.S. securities; and 102% of the market value of loans on all other securities. Refer to "Fair Value Measurements" below for details of Alliant Energy's, IPL's and WPL's fair value of invested collateral and amounts due to borrowers for the securities lending program.

Fair Value Measurements - The following tables report a framework for measuring fair value. The fair value hierarchy 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. Alliant Energy's, IPL's and WPL's investments in equity and fixed income securities held in registered investment companies and directly held equity securities are valued at the closing price reported in the active market in which the securities are traded. Level 1 plan assets also include interest-bearing cash, which is held in money market accounts managed by an affiliate of the trustee and money market funds within their securities lending invested collateral.

Level 2 - Pricing inputs are quoted prices for similar asset or liabilities in active markets, quoted prices for identical or similar assets or liabilities in inactive markets, inputs other than quoted prices that are observable for the asset or liability and inputs that are derived principally from or corroborated by observable market data by correlation or other means. Alliant Energy's, IPL's and WPL's investments in corporate bonds and government and agency obligations are valued at the closing price reported in the active market for similar assets in which the individual securities are traded or based on yields currently available on comparable securities of issuers with similar credit ratings. Alliant Energy's, IPL's and WPL's investments in equity and fixed income securities in common/collective trusts are valued at the net asset value of shares held by the plans, which is based on the fair market value of the underlying investments in equity and fixed income securities of the common/collective trusts. Level 2 plan assets also consist of asset backed securities within their securities lending invested collateral.

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. Alliant Energy's, IPL's and WPL's Level 3 plan assets include certain asset backed securities and corporate bonds within their securities lending invested collateral.

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.

The methods described above may produce a fair value calculation that may not be indicative of net realizable value or reflective of future fair values. Furthermore, while Alliant Energy, IPL and WPL believe their valuation methods are appropriate and consistent with other market participants, the use of different methodologies or assumptions to determine the fair value of certain financial instruments could result in a different fair value measurement at the reporting date.

At Dec. 31, the fair values of Alliant Energy's qualified and non-qualified defined benefit pension plans assets by asset category and fair value hierarchy level were as follows (in millions):

Alliant Energy

	2011									2010
	Fair Value			Level 1		Level 2		Level 3		Fair Value			Level 1		Level 2		Level 3
Cash and equivalents	$	117.5		$	117.5	$	—	$	—	$	11.1		$	11.1	$	—	$	—
Equity securities:
U.S. large cap core		110.7			110.7		—		—		118.4			118.4		—		—
U.S. large cap value		91.6			—		91.6		—		100.4			—		100.4		—
U.S. large cap growth		91.5			—		91.5		—		101.0			—		101.0		—
U.S. small cap value		25.7			—		25.7		—		29.0			—		29.0		—
U.S. small cap growth		21.7			21.7		—		—		16.6			16.6		—		—
International - developed markets		126.4			65.4		61.0		—		142.3			76.0		66.3		—
International - emerging markets		30.4			30.4		—		—		34.1			34.1		—		—
Fixed income securities:
Corporate bonds		57.1			—		57.1		—		54.2			—		54.2		—
Government and agency obligations		87.8			—		87.8		—		78.9			—		78.9		—
Fixed income funds		146.7			0.2		146.5		—		142.7			0.2		142.5		—
Securities lending invested collateral		9.3			4.7		2.8		1.8		17.3			3.0		11.5		2.8
		916.4		$	350.6	$	564.0	$	1.8		846.0		$	259.4	$	583.8	$	2.8
Accrued investment income		1.0									1.2
Due to brokers, net (a)		(4.7	)								(0.6	)
Due to borrowers for securities lending program		(15.3	)								(23.6	)
Total pension plan assets	$	897.4								$	823.0

(a) This category represents pending trades with brokers.

At Dec. 31, the fair values of IPL's and WPL's qualified and non-qualified defined benefit pension plan assets associated with IPL's and WPL's current and former non-bargaining employees who are participants in Alliant Energy and Corporate Services sponsored plans that were directly assigned to IPL and WPL, along with the percentage these assets represent of the fair values by asset category and fair value hierarchy level shown in the above table were as follows (dollars in millions):

	IPL						WPL
	2011			2010			2011			2010
Fair values of directly assigned amounts	$	127.4		$	127.6		$	97.0		$	95.6
Percentage represented		14.2	%		15.5	%		10.8	%		11.6	%

At Dec. 31, the fair values of IPL's and WPL's qualified defined benefit pension plans assets by asset category and fair value hierarchy level were as follows (in millions):

IPL

	2011									2010
	Fair Value			Level 1		Level 2		Level 3		Fair Value			Level 1		Level 2		Level 3
Cash and equivalents	$	39.1		$	39.1	$	—	$	—	$	3.5		$	3.5	$	—	$	—
Equity securities:
U.S. large cap core		36.8			36.8		—		—		37.0			37.0		—		—
U.S. large cap value		30.5			—		30.5		—		31.4			—		31.4		—
U.S. large cap growth		30.5			—		30.5		—		31.5			—		31.5		—
U.S. small cap value		8.6			—		8.6		—		9.0			—		9.0		—
U.S. small cap growth		7.2			7.2		—		—		5.2			5.2		—		—
International - developed markets		42.1			21.8		20.3		—		44.4			23.7		20.7		—
International - emerging markets		10.1			10.1		—		—		10.7			10.7		—		—
Fixed income securities:
Corporate bonds		19.0			—		19.0		—		16.9			—		16.9		—
Government and agency obligations		29.2			—		29.2		—		24.6			—		24.6		—
Fixed income funds		48.8			0.1		48.7		—		44.5			—		44.5		—
Securities lending invested collateral		3.1			1.6		0.9		0.6		5.4			0.9		3.6		0.9
		305.0		$	116.7	$	187.7	$	0.6		264.1		$	81.0	$	182.2	$	0.9
Accrued investment income		0.4									0.4
Due to brokers, net (a)		(1.6	)								(0.2	)
Due to borrowers for securities lending program		(5.1	)								(7.4	)
Total pension plan assets	$	298.7								$	256.9

WPL

	2011									2010
	Fair Value			Level 1		Level 2		Level 3		Fair Value			Level 1		Level 2		Level 3
Cash and equivalents	$	37.9		$	37.9	$	—	$	—	$	3.4		$	3.4	$	—	$	—
Equity securities:
U.S. large cap core		35.7			35.7		—		—		36.7			36.7		—		—
U.S. large cap value		29.6			—		29.6		—		31.2			—		31.2		—
U.S. large cap growth		29.5			—		29.5		—		31.3			—		31.3		—
U.S. small cap value		8.3			—		8.3		—		9.0			—		9.0		—
U.S. small cap growth		7.0			7.0		—		—		5.2			5.2		—		—
International - developed markets		40.8			21.1		19.7		—		44.1			23.6		20.5		—
International - emerging markets		9.8			9.8		—		—		10.6			10.6		—		—
Fixed income securities:
Corporate bonds		18.4			—		18.4		—		16.8			—		16.8		—
Government and agency obligations		28.3			—		28.3		—		24.5			—		24.5		—
Fixed income funds		47.4			0.1		47.3		—		44.2			—		44.2		—
Securities lending invested collateral		3.0			1.5		0.9		0.6		5.4			1.0		3.5		0.9
		295.7		$	113.1	$	182.0	$	0.6		262.4		$	80.5	$	181.0	$	0.9
Accrued investment income		0.3									0.3
Due to brokers, net (a)		(1.5	)								(0.2	)
Due to borrowers for securities lending program		(4.9	)								(7.3	)
Total pension plan assets	$	289.6								$	255.2

(a) This category represents pending trades with brokers.

At Dec. 31, the fair values of Alliant Energy's, IPL's and WPL's other postretirement benefits plans assets by asset category and fair value hierarchy level were as follows (in millions):

Alliant Energy

	2011									2010
	Fair Value			Level 1		Level 2		Level 3		Fair Value			Level 1		Level 2		Level 3
Cash and equivalents	$	14.0		$	14.0	$	—	$	—	$	15.4		$	15.4	$	—	$	—
Equity securities:
U.S. large cap core		37.1			37.1		—		—		38.6			38.6		—		—
U.S. large cap value		2.4			—		2.4		—		2.7			—		2.7		—
U.S. large cap growth		2.4			—		2.4		—		2.7			—		2.7		—
U.S. mid cap core		17.8			17.8		—		—		18.6			18.6		—		—
U.S. small cap core		4.7			4.7		—		—		3.8			3.8		—		—
U.S. small cap value		0.6			—		0.6		—		0.8			—		0.8		—
U.S. small cap growth		0.5			0.5		—		—		0.4			0.4		—		—
International - developed markets		3.3			1.7		1.6		—		3.9			2.1		1.8		—
International - emerging markets		0.8			0.8		—		—		0.9			0.9		—		—
Fixed income securities:
Corporate bonds		6.1			—		6.1		—		6.3			—		6.3		—
Government and agency obligations		5.6			—		5.6		—		4.9			—		4.9		—
Fixed income funds		25.4			21.6		3.8		—		24.0			20.1		3.9		—
Securities lending invested collateral		0.4			0.2		0.1		0.1		0.8			0.2		0.5		0.1
		121.1		$	98.4	$	22.6	$	0.1		123.8		$	100.1	$	23.6	$	0.1
Accrued investment income		0.1									0.1
Due to brokers, net (a)		(0.2	)								(0.1	)
Due to borrowers for securities lending program		(0.6	)								(1.1	)
Total other postretirement benefits plan assets	$	120.4								$	122.7

IPL

	2011									2010
	Fair Value			Level 1		Level 2		Level 3		Fair Value			Level 1		Level 2		Level 3
Cash and equivalents	$	2.1		$	2.1	$	—	$	—	$	3.5		$	3.5	$	—	$	—
Equity securities:
U.S. large cap core		29.3			29.3		—		—		30.7			30.7		—		—
U.S. large cap value		0.8			—		0.8		—		1.0			—		1.0		—
U.S. large cap growth		0.8			—		0.8		—		1.0			—		1.0		—
U.S. mid cap core		14.7			14.7		—		—		15.3			15.3		—		—
U.S. small cap value		0.2			—		0.2		—		0.3			—		0.3		—
U.S. small cap growth		0.2			0.2		—		—		0.2			0.2		—		—
International - developed markets		1.2			0.6		0.6		—		1.4			0.8		0.6		—
International - emerging markets		0.3			0.3		—		—		0.3			0.3		—		—
Fixed income securities:
Corporate bonds		4.6			—		4.6		—		4.5			—		4.5		—
Government and agency obligations		4.1			—		4.1		—		3.3			—		3.3		—
Fixed income funds		16.5			15.1		1.4		—		16.0			14.6		1.4		—
Securities lending invested collateral		0.2			0.1		0.1		—		0.5			0.1		0.3		0.1
		75.0		$	62.4	$	12.6	$	—		78.0		$	65.5	$	12.4	$	0.1
Accrued investment income		0.1									0.2
Due to borrowers for securities lending program		(0.4	)								(0.7	)
Total other postretirement benefits plan assets	$	74.7								$	77.5

WPL

	2011									2010
	Fair Value			Level 1		Level 2		Level 3		Fair Value			Level 1		Level 2		Level 3
Cash and equivalents	$	10.5		$	10.5	$	—	$	—	$	10.7		$	10.7	$	—	$	—
Equity securities:
U.S. large cap core		1.2			1.2		—		—		1.3			1.3		—		—
U.S. large cap value		1.0			—		1.0		—		1.1			—		1.1		—
U.S. large cap growth		1.0			—		1.0		—		1.1			—		1.1		—
U.S. small cap core		4.7			4.7		—		—		3.8			3.8		—		—
U.S. small cap value		0.3			—		0.3		—		0.3			—		0.3		—
U.S. small cap growth		0.2			0.2		—		—		0.2			0.2		—		—
International - developed markets		1.3			0.7		0.6		—		1.6			0.8		0.8		—
International - emerging markets		0.3			0.3		—		—		0.4			0.4		—		—
Fixed income securities:
Corporate bonds		1.1			—		1.1		—		1.4			—		1.4		—
Government and agency obligations		1.0			—		1.0		—		1.0			—		1.0		—
Fixed income funds		2.6			1.0		1.6		—		2.3			0.7		1.6		—
Securities lending invested collateral		0.1			0.1		—		—		0.2			0.1		0.1		—
		25.3		$	18.7	$	6.6	$	—		25.4		$	18.0	$	7.4	$	—
Due to brokers, net (a)		(0.1	)								(0.1	)
Due to borrowers for securities lending program		(0.1	)								(0.3	)
Total other postretirement benefits plan assets	$	25.1								$	25.0

(a) This category represents pending trades with brokers.

For the various Alliant Energy defined benefit pension and other postretirement benefits plans, Alliant Energy common stock represented less than 1% of total plan assets at Dec. 31, 2011 and 2010.

Alliant Energy Cash Balance Plan - Alliant Energy's defined benefit pension plans include the Cash Balance Plan that provides benefits for certain non-bargaining unit employees. The Cash Balance Plan has been closed to new hires since 2005. Effective 2008, Alliant Energy amended the Cash Balance Plan by discontinuing additional contributions into employees' Cash Balance Plan accounts. Also effective 2008, Alliant Energy increased its level of contributions to its 401(k) Savings Plan, which offset the impact of discontinuing additional contributions into the employees' Cash Balance Plan accounts. In 2009, Alliant Energy amended the Cash Balance Plan by changing participants' future interest credit formula to use the annual change in the consumer price index as the interest credit. This amendment provides participants an interest crediting rate that is 3% more than the annual change in the consumer price index. Refer to Note 13(b) for discussion of a class action lawsuit filed against the Cash Balance Plan in 2008 and the IRS review of the tax qualified status of the Plan.

401(k) Savings Plans - A significant number of Alliant Energy, IPL and WPL employees participate in defined contribution retirement plans (401(k) savings plans). The number of employees participating in these plans has increased recently as certain bargaining unit employees have elected to participate in defined contribution retirement plans instead of defined benefit pension plans. In 2009, Alliant Energy, IPL and WPL implemented several cost saving initiatives to reduce operation and maintenance expenses, including suspension of a portion of 401(k) savings plans contributions during the second half of 2009. Alliant Energy common stock represented 14.6% and 12.9% of total assets held in 401(k) savings plans at Dec. 31, 2011 and 2010, respectively. Alliant Energy's, IPL's and WPL's costs related to the 401(k) savings plans, which are partially based on the participants' level of contribution, were as follows (in millions):

	Alliant Energy						IPL						WPL
	2011		2010		2009		2011		2010		2009		2011		2010		2009
401(k) savings plans costs	$	18.7	$	18.5	$	16.2	$	9.2	$	8.8	$	2.8	$	8.4	$	8.9	$	4.3

(b) Equity Incentive Plans - In 2010, Alliant Energy's shareowners approved the Alliant Energy 2010 Omnibus Incentive Plan (OIP), which permits the grant of stock options, restricted stock, restricted stock units, performance shares, performance units, and other stock-based awards and cash incentive awards to key employees. At Dec. 31, 2011, performance shares and restricted stock were outstanding and 4.3 million shares of Alliant Energy's common stock remained available for grants under the OIP. Upon shareowner approval of the OIP, the Alliant Energy 2002 Equity Incentive Plan (EIP) terminated resulting in no new awards authorized to be granted under the EIP. All awards previously granted under the EIP that are still outstanding remain valid and continue to be subject to all of the terms and conditions of the EIP. At Dec. 31, 2011, non-qualified stock options, restricted stock and performance shares were outstanding under the EIP and another predecessor plan under which new awards can no longer be granted. Alliant Energy satisfies payouts related to equity awards under the OIP and EIP through the issuance of new shares of its common stock. Alliant Energy also has the Alliant Energy Director Long Term Incentive Plan (DLIP), which permits the grant of long-term incentive awards, including performance units and restricted cash awards to certain key employees. At Dec. 31, 2011, performance units and performance contingent cash awards were outstanding under the DLIP. There is no limit to the number of grants that can be made under the DLIP and Alliant Energy satisfies all payouts under the DLIP through cash.

A summary of compensation expense and the related income tax benefits recognized for share-based compensation awards was as follows (in millions):

	Alliant Energy						IPL						WPL
	2011		2010		2009		2011		2010		2009		2011		2010		2009
Compensation expense	$	10.1	$	7.5	$	2.8	$	5.5	$	4.0	$	1.6	$	4.1	$	3.0	$	1.1
Income tax benefits		4.0		3.0		1.2		2.2		1.6		0.7		1.7		1.2		0.4

As of Dec. 31, 2011, total unrecognized compensation cost related to nonvested share-based compensation awards was $9.3 million, which is expected to be recognized over a weighted average period between one and two years. Share-based compensation expense is recognized on a straight-line basis over the requisite service periods and is primarily recorded in "Utility - other operation and maintenance" in the Consolidated Statements of Income.

Performance Shares and Units - Payouts of performance shares and units to key employees are contingent upon achievement over three-year periods of specified performance criteria, which currently include metrics of total shareowner return relative to investor-owned utility peer groups. Payouts of nonvested performance shares and units issued prior to 2012 are prorated at retirement, death, disability or involuntary termination without cause based on time worked during the performance period and achievement of the performance criteria. Participants' nonvested performance shares and units issued prior to 2012 are forfeited if the participant voluntarily leaves Alliant Energy or is terminated for cause. Nonvested performance shares and units do not have non-forfeitable rights to dividends when dividends are paid to common shareowners. Alliant Energy anticipates making future payouts of its performance shares and units in cash; therefore, performance shares and units are accounted for as liability awards.

Performance Shares - Performance shares can be paid out in shares of Alliant Energy's common stock, cash or a combination of cash and stock and are adjusted by a performance multiplier, which ranges from zero to 200% based on the performance criteria. A summary of the performance shares activity was as follows:

	2011			2010			2009
	Shares (a)			Shares (a)			Shares (a)
Nonvested shares, Jan. 1		234,518			256,579			208,579
Granted		64,217			72,487			152,735
Vested (b)		(57,838	)		—			(84,633	)
Forfeited (c)		(3,918	)		(94,548	)		(20,102	)
Nonvested shares, Dec. 31		236,979			234,518			256,579

(a) Share amounts represent the target number of performance shares. Each performance share's value is based on the price of one share of Alliant Energy's common stock at the end of the performance period. The actual number of shares that will be paid out upon vesting is dependent upon actual performance and may range from zero to 200% of the target number of shares.

(b) In 2011, 57,838 performance shares granted in 2008 vested at 75% of the target, resulting in a payout valued at $1.6 million, which consisted of a combination of cash and common stock (1,387 shares). In 2009, 84,633 performance shares granted in 2006 vested resulting in a payout valued at $4.1 million, which consisted of a combination of cash and common stock (51,189 shares).

(c) In 2010, 57,100 performance shares granted in 2007 were forfeited without payout because the specified performance criteria for such shares were not met. The remaining forfeitures during 2011, 2010 and 2009 were primarily caused by retirements and voluntary terminations of participants.

Performance Units - Alliant Energy granted share-based compensation awards to key employees in 2011 and 2010 referred to as performance units. The performance units and the performance contingent cash awards discussed below were granted in 2011 and 2010 in lieu of time-based restricted stock. Performance units must be paid out in cash and are adjusted by a performance multiplier, which ranges from zero to 200% based on the performance criteria. A summary of the performance unit activity was as follows:

	2011			2010
	Units (a)			Units (a)
Nonvested units, Jan. 1		23,128			—
Granted		23,975			23,795
Forfeited		(4,107	)		(667	)
Nonvested units, Dec. 31		42,996			23,128

(a) Unit amounts represent the target number of performance units. Each performance unit's value is based on the average price of one share of Alliant Energy's common stock on the grant date of the award. The actual payout for performance units is dependent upon actual performance and may range from zero to 200% of the target number of units.

Fair Value of Awards - Information related to fair values of nonvested performance shares and units at Dec. 31, 2011, by year of grant, were as follows:

	Performance Shares									Performance Units
	2011 Grant			2010 Grant			2009 Grant			2011 Grant			2010 Grant
Nonvested awards		62,170			62,829			111,980			22,279			20,717
Alliant Energy common stock closing price on Dec. 31, 2011	$	44.11		$	44.11		$	44.11
Alliant Energy common stock average price on grant date										$	38.75		$	32.56
Estimated payout percentage based on performance criteria		106	%		155	%		163	%		106	%		155	%
Fair values of each nonvested award	$	46.76		$	68.37		$	71.68		$	41.08		$	50.46

At Dec. 31, 2011, fair values of nonvested performance shares and units were calculated using a Monte Carlo simulation to determine the anticipated total shareowner returns of Alliant Energy and its investor-owned utility peer groups. Expected volatility was based on historical volatilities using daily stock prices over the past three years. Expected dividend yields were calculated based on the most recent quarterly dividend rates announced prior to the measurement date and stock prices at the measurement date. The risk-free interest rate was based on the three-year U.S. Treasury rate in effect as of the measurement date.

Restricted Stock - Restricted stock issued under the EIP consists of time-based and performance-contingent restricted stock.

Time-based Restricted Stock - The current restriction period for outstanding time-based restricted stock is up to three years. Nonvested shares of time-based restricted stock generally become vested upon retirement. Compensation costs related to awards granted to retirement-eligible employees are generally expensed on the date of grant. Participants' nonvested time-based restricted stock issued prior to 2012 is forfeited if the participant voluntarily leaves Alliant Energy or is terminated for cause. Nonvested time-based restricted stock issued prior to 2012 is fully vested in the event of retirement, death, disability or involuntary termination without cause. The fair value of time-based restricted stock is based on the average market price at the grant date. A summary of the time-based restricted stock activity was as follows:

	2011					2010					2009
	Shares			Weighted Average Fair Value		Shares			Weighted Average Fair Value		Shares			Weighted Average Fair Value
Nonvested shares, Jan. 1		70,033		$	32.27		125,349		$	32.47		156,807		$	32.80
Granted		5,000			39.86		—			—		51,236			29.40
Vested		(38,633	)		34.60		(54,016	)		32.72		(79,459	)		31.08
Forfeited		(600	)		29.41		(1,300	)		32.78		(3,235	)		33.97
Nonvested shares, Dec. 31		35,800			30.87		70,033			32.27		125,349			32.47

Performance-contingent Restricted Stock - Vesting of performance-contingent restricted stock grants are based on the achievement of certain performance targets (currently specified earnings growth). The performance metric for the 2011, 2010 and 2009 grants is consolidated net income growth. If performance targets are not met within the performance period, which currently ranges from two to four years, these restricted stock grants are forfeited. Nonvested shares of performance- contingent restricted stock issued prior to 2012 are prorated at retirement based on time worked during the performance period and vest only if and when the performance criteria are met. Participants' nonvested performance-contingent restricted stock issued prior to 2012 is forfeited if the participant voluntarily leaves Alliant Energy for reasons other than retirement. The fair value of performance-contingent restricted stock is based on the average market price at the grant date. A summary of the performance-contingent restricted stock activity was as follows:

	2011					2010					2009
	Shares			Weighted Average Fair Value		Shares			Weighted Average Fair Value		Shares		Weighted Average Fair Value
Nonvested shares, Jan. 1		296,190		$	32.32		226,007		$	32.25		124,185	$	39.28
Granted		64,217			38.75		72,487			32.56		101,822		23.67
Vested		(53,274	)		37.93		—			—		—		—
Forfeited		(5,395	)		38.00		(2,304	)		32.56		—		—
Nonvested shares, Dec. 31		301,738			32.60		296,190			32.32		226,007		32.25

Non-qualified Stock Options - Options granted under the plans were granted at the market price of the shares on the date of grant, vest over three years and expire no later than 10 years after the grant date. Options become fully vested upon retirement and remain exercisable at any time prior to their expiration date or for three years after the effective date of the retirement, whichever period is shorter. Options become fully vested upon death or disability and remain exercisable at any time prior to their expiration date or for one year after the effective date of the death or disability, whichever period is shorter. If participants leave Alliant Energy for reasons other than retirement, death or disability, their options that are not vested are forfeited and their vested options expire three months after their departure. Alliant Energy has not granted any options since 2004. A summary of the stock option activity was as follows:

	2011					2010					2009
	Shares			Weighted Average Exercise Price		Shares			Weighted Average Exercise Price		Shares			Weighted Average Exercise Price
Outstanding, Jan. 1		163,680		$	24.51		384,331		$	27.02		497,183		$	27.30
Exercised		(99,791	)		24.71		(191,433	)		28.93		(39,877	)		25.80
Expired		—			—		(29,218	)		28.59		(56,098	)		29.88
Forfeited		—			—		—			—		(16,877	)		28.67
Outstanding and exercisable, Dec. 31		63,889			24.21		163,680			24.51		384,331			27.02

The weighted average remaining contractual term for options outstanding and exercisable at Dec. 31, 2011 was between one and two years. The aggregate intrinsic value of options outstanding and exercisable at Dec. 31, 2011 was $1.3 million.

Other information related to stock option activity was as follows (in millions):

	2011		2010		2009
Cash received from stock options exercised	$	2.5	$	5.5	$	1.0
Aggregate intrinsic value of stock options exercised		1.6		1.1		0.1
Income tax benefit from the exercise of stock options		0.7		0.4		0.1

Performance Contingent Cash Awards - Alliant Energy granted share-based compensation awards to key employees in 2011 and 2010 referred to as performance contingent cash awards. Performance contingent cash award payouts to key employees are based on the achievement of certain performance targets (currently specified consolidated net income growth). If performance targets are not met within the performance period, which currently ranges from two to four years, there are no payouts for these awards. Nonvested awards issued prior to 2012 are prorated at retirement based on time worked during the performance period and achievement of the performance criteria. Participants' nonvested awards issued prior to 2012 are forfeited if the participant voluntarily leaves Alliant Energy for reasons other than retirement. Each performance contingent cash award's value is based on the price of one share of Alliant Energy's common stock at the end of the performance period. Alliant Energy accounts for performance contingent cash awards as liability awards because payouts will be made in the form of cash. A summary of the performance contingent cash awards activity was as follows:

	2011			2010
	Awards			Awards
Nonvested awards, Jan. 1		23,428			—
Granted		23,975			23,795
Forfeited		(727	)		(367	)
Nonvested awards, Dec. 31		46,676			23,428

(c) Deferred Compensation Plan - Alliant Energy maintains a deferred compensation plan under which key employees may defer up to 100% of base salary and incentive compensation and directors may elect to defer all or part of their retainer and committee fees. Key employees who have made the maximum allowed contribution to the Alliant Energy 401(k) Savings Plan may receive an additional credit to the deferred compensation plan. Key employees and directors may elect to have their deferrals credited to a company stock account, an interest account or equity accounts based on index funds.

Company Stock Accounts - The deferred compensation plan does not permit diversification of deferrals credited to the company stock account and all distributions from participants' company stock accounts are made in the form of shares of Alliant Energy common stock. The deferred compensation obligations for participants' company stock accounts are recorded in "Additional paid-in capital" and the shares of Alliant Energy common stock held in a rabbi trust to satisfy this obligation are recorded in "Shares in deferred compensation trust" on Alliant Energy's Consolidated Balance Sheets. At Dec. 31, the carrying value of the deferred compensation obligation for the company stock accounts and the shares in the deferred compensation trust based on the historical value of the shares of Alliant Energy common stock contributed to the rabbi trust, and the fair market value of the shares held in the rabbi trust were as follows (in millions):

	2011		2010
Carrying value	$	8.3	$	7.6
Fair market value		11.6		9.1

Interest and Equity Accounts - Distributions from participants' interest and equity accounts are in the form of cash payments. The deferred compensation obligations for participants' interest and equity accounts are recorded in "Pension and other benefit obligations" on Alliant Energy's and IPL's Consolidated Balance Sheets. At Dec. 31, the carrying value of Alliant Energy's and IPL's deferred compensation obligations for participants' interest and equity accounts was as follows (in millions):

	Alliant Energy				IPL
	2011		2010		2011		2010
Carrying value	$	20.5	$	20.5	$	5.0	$	5.2