Benefit Plans

9 Months Ended

Sep. 30, 2011

Benefit Plans

(5) BENEFIT PLANS

(a) Pension and Other Postretirement Benefits Plans -

Net Periodic Benefit Costs—The components of Alliant Energy's, IPL's and WPL's net periodic benefit costs (credits) for their defined benefit pension and other postretirement benefits plans for the three and nine months ended Sep. 30 were as follows (in millions):

Alliant Energy	Defined Benefit Pension Plans												Other Postretirement Benefits Plans (a)
	Three Months						Nine Months						Three Months						Nine Months
	2011			2010			2011			2010			2011			2010			2011			2010
Service cost	$	2.9		$	3.0		$	8.6		$	9.0		$	1.6		$	2.2		$	5.4		$	7.0
Interest cost		13.0			13.1			39.0			39.3			2.8			3.5			9.5			11.4
Expected return on plan assets		(15.9	)		(15.6	)		(47.8	)		(46.6	)		(2.0	)		(1.9	)		(5.9	)		(5.8	)
Amortization of:
Transition obligation		—			—			—			—			—			—			—			0.1
Prior service cost (credit)		0.2			0.2			0.6			0.6			(3.4	)		(1.2	)		(6.6	)		(1.3	)
Actuarial loss		5.2			5.9			15.7			17.9			1.2			2.2			4.0			5.3
Additional benefit costs (b)		1.3			—			10.2			—			—			—			—			—
Settlement losses (c)		1.1			1.4			1.1			1.4			—			—			—			—
	$	7.8		$	8.0		$	27.4		$	21.6		$	0.2		$	4.8		$	6.4		$	16.7

	Qualified Defined Benefit Pension Plans												Other Postretirement Benefits Plans (a)
	Three Months						Nine Months						Three Months						Nine Months
IPL	2011			2010			2011			2010			2011			2010			2011			2010
Service cost	$	1.5		$	1.5		$	4.6		$	4.6		$	0.6		$	0.8		$	2.0		$	2.6
Interest cost		4.2			4.2			12.5			12.4			1.3			1.6			4.3			5.2
Expected return on plan assets		(5.0	)		(4.9	)		(15.0	)		(14.6	)		(1.4	)		(1.3	)		(4.0	)		(4.0	)
Amortization of:
Transition obligation		—			—			—			—			—			—			—			0.1
Prior service cost (credit)		0.2			0.2			0.4			0.5			(1.8	)		(0.5	)		(3.3	)		(0.6	)
Actuarial loss		1.4			1.8			4.3			5.4			0.7			1.2			2.2			2.8
	$	2.3		$	2.8		$	6.8		$	8.3		($	0.6	)	$	1.8		$	1.2		$	6.1

	Qualified Defined Benefit Pension Plan												Other Postretirement Benefits Plans (a)
	Three Months						Nine Months						Three Months						Nine Months
WPL	2011			2010			2011			2010			2011			2010			2011			2010
Service cost	$	1.1		$	1.2		$	3.4		$	3.6		$	0.7		$	0.9		$	2.2		$	2.7
Interest cost		4.1			3.9			12.1			11.8			1.1			1.3			3.7			4.2
Expected return on plan assets		(5.0	)		(4.8	)		(15.0	)		(14.3	)		(0.3	)		(0.4	)		(1.0	)		(1.0	)
Amortization of:
Prior service cost (credit)		0.1			0.2			0.4			0.4			(1.1	)		(0.2	)		(2.2	)		(0.2	)
Actuarial loss		1.8			2.2			5.3			6.4			0.5			0.7			1.6			1.7
	$	2.1		$	2.7		$	6.2		$	7.9		$	0.9		$	2.3		$	4.3		$	7.4

(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 remeasurement resulted in a decrease in Alliant Energy's postretirement benefit obligations of $64 million ($38 million for IPL, $16 million for WPL and $10 million for Corporate Services) 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 $4.3 million, $2.7 million and $1.4 million during the three months ended Sep. 30, 2011, respectively, and $7.1 million, $4.5 million, and $2.4 million during the nine months ended Sep. 30, 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) Alliant Energy reached an agreement with the IRS, which resulted in a favorable determination letter for the Alliant Energy Cash Balance Pension Plan (Plan) during the first quarter of 2011. The agreement with the IRS required Alliant Energy to amend the Plan, which was completed in the second quarter of 2011 resulting in aggregate additional benefits of $10.2 million to be paid to certain former participants in the Plan in the second half of 2011. Alliant Energy recognized $1.3 million and $10.2 million of additional benefits costs during the three and nine months ended Sep. 30, 2011, respectively, related to these benefits. Refer to Note 11(c) for additional information regarding the Plan.

(c) For both the three and nine months ended Sep. 30, 2011 and 2010, settlement losses of $1.1 million and $1.4 million, respectively, related to payments made to retired executives.

In the above tables for IPL and WPL, 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. The other postretirement benefits costs represent costs for all IPL and WPL employees. Corporate Services provides services to IPL and WPL, and as a result, IPL and WPL are allocated pension and other postretirement benefits costs (credits) associated with Corporate Services employees. The following table includes qualified pension benefits costs for IPL's and WPL's non-bargaining employees who are participants in other Alliant Energy plans, and the allocated qualified pension and other postretirement benefits costs (credits) associated with Corporate Services employees providing services to IPL and WPL for the three and nine months ended Sep. 30 (in millions):

	Qualified Pension Benefits Costs (a)								Other Postretirement Benefits Costs (Credits)
	Three Months				Nine Months				Three Months					Nine Months
	2011		2010		2011		2010		2011			2010		2011		2010
IPL	$	0.7	$	—	$	6.0	$	—	$	—		$	0.4	$	0.4	$	1.7
WPL		0.5		0.1		3.8		0.5		(0.1	)		0.3		0.2		1.1

(a) For the three and nine months ended Sep. 30, 2011, additional qualified pension benefits costs resulting from the second quarter 2011 amendment to the Cash Balance Pension Plan allocated to IPL were $0.8 million and $6.3 million, respectively, and to WPL were $0.4 million and $3.4 million, respectively.

Alliant Energy sponsors several non-qualified defined benefit pension plans that cover certain current and former key employees. The pension costs allocated to IPL and WPL for these plans for the three and nine months ended Sep. 30 were as follows (in millions):

	IPL								WPL
	Three Months				Nine Months				Three Months				Nine Months
	2011		2010		2011		2010		2011		2010		2011		2010
Pension costs	$	1.3	$	1.5	$	2.5	$	3.0	$	0.8	$	1.0	$	1.5	$	1.8

Estimated Future and Actual Employer Contributions—Alliant Energy's, IPL's, and WPL's estimated and actual funding for the qualified defined benefit pension, non-qualified defined benefit pension and other postretirement benefits plans for 2011 are as follows (in millions):

	Estimated for Calendar Year 2011								Actual Through Sep. 30, 2011
	Alliant Energy		IPL			WPL			Alliant Energy		IPL			WPL
Qualified defined benefit pension plans	$	10	$	—		$	—		$	9	$	—		$	—
Non-qualified defined benefit pension plans		7		(a	)		(a	)		6		(a	)		(a	)
Other postretirement benefits plans		9		3			5			7		2			4

(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.

Alliant Energy Cash Balance Pension Plan (Plan)—Refer to Note 11(c) for discussion of a class action lawsuit filed against the 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). For the three and nine months ended Sep. 30, 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 (a)								WPL (a)
	Three Months				Nine Months				Three Months				Nine Months				Three Months				Nine Months
	2011		2010		2011		2010		2011		2010		2011		2010		2011		2010		2011		2010
401(k) costs	$	4.5	$	4.4	$	14.5	$	13.9	$	2.2	$	2.1	$	7.1	$	6.6	$	2.0	$	2.2	$	6.6	$	6.8

(a) IPL's and WPL's amounts include allocated costs associated with Corporate Services employees.

(b) Equity Incentive Plans—A summary of compensation expense and the related income tax benefits recognized for share-based compensation awards for the three and nine months ended Sep. 30 was as follows (in millions):

	Alliant Energy								IPL								WPL
	Three Months				Nine Months				Three Months				Nine Months				Three Months				Nine Months
	2011		2010		2011		2010		2011		2010		2011		2010		2011		2010		2011		2010
Compensation expense		$0.1	$	2.6		$4.9	$	6.2		$0.1	$	1.4		$2.7	$	3.3		$0.1	$	1.1		$2.0	$	2.5
Income tax benefits		0.1		1.1		2.0		2.5		0.1		0.5		1.1		1.3		—		0.4		0.8		1.0

As of Sep. 30, 2011, total unrecognized compensation cost related to share-based compensation awards was $12.9 million, which is expected to be recognized over a weighted average period of 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 Condensed Consolidated Statements of Income.

Performance Shares and Units—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—A summary of the performance shares activity for the nine months ended Sep. 30 was as follows:

	2011			2010
	Shares (a)			Shares (a)
Nonvested shares, Jan. 1		234,518			256,579
Granted		64,217			72,487
Vested (b)		(57,838	)		—
Forfeited (c)		(3,918	)		(83,786	)
Nonvested shares, Sep. 30		236,979			245,280

(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 the first quarter of 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).

(c) In the first quarter of 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 the nine months ended Sep. 30, 2011 and 2010 were primarily caused by retirements and voluntary terminations of participants.

Performance Units—A summary of the performance unit activity for the nine months ended Sep. 30 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, Sep. 30		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 Sep. 30, 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 Sep. 30, 2011	$	38.68		$	38.68		$	38.68
Alliant Energy common stock average price on grant date										$	38.75		$	32.56
Estimated payout percentage based on performance criteria		97	%		133	%		131	%		97	%		133	%
Fair values of each nonvested award	$	37.52		$	51.44		$	50.67		$	37.59		$	43.30

At Sep. 30, 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 group. 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 consists of time-based and performance-contingent restricted stock.

Time-based restricted stock—A summary of the time-based restricted stock activity for the nine months ended Sep. 30 was as follows:

	2011					2010
	Shares			Weighted Average Fair Value		Shares			Weighted Average Fair Value
Nonvested shares, Jan. 1		70,033		$	32.27		125,349		$	32.47
Granted during first quarter		5,000			39.86		—			—
Vested		(38,633	)		34.60		(51,736	)		32.87
Forfeited		(600	)		29.41		(1,300	)		32.78
Nonvested shares, Sep. 30		35,800			30.87		72,313			32.18

Performance-contingent restricted stock—A summary of the performance-contingent restricted stock activity for the nine months ended Sep. 30 was as follows:

	2011					2010
	Shares			Weighted Average Fair Value		Shares			Weighted Average Fair Value
Nonvested shares, Jan. 1		296,190		$	32.32		226,007		$	32.25
Granted during first quarter		64,217			38.75		72,487			32.56
Vested		(53,274	)		37.93		—			—
Forfeited		(5,395	)		38.00		(2,304	)		32.56
Nonvested shares, Sep. 30		301,738			32.60		296,190			32.32

Non-qualified Stock Options—A summary of the stock option activity for the nine months ended Sep. 30 was as follows:

	2011					2010
	Shares			Weighted Average Exercise Price		Shares			Weighted Average Exercise Price
Outstanding, Jan. 1		163,680		$	24.51		384,331		$	27.02
Exercised		(62,481	)		27.10		(151,693	)		28.34
Expired		—			—		(29,218	)		28.59
Outstanding and exercisable, Sep. 30		101,199			22.92		203,420			25.81

The weighted average remaining contractual term for options outstanding and exercisable at Sep. 30, 2011 was between one and two years. The aggregate intrinsic value of options outstanding and exercisable at Sep. 30, 2011 was $1.6 million.

Other information related to stock option activity for the three and nine months ended Sep. 30 was as follows (in millions):

	Three Months				Nine Months
	2011		2010		2011		2010
Cash received from stock options exercised	$	0.1	$	2.0	$	1.7	$	4.3
Aggregate intrinsic value of stock options exercised		—		0.4		0.8		0.9
Income tax benefit from the exercise of stock options		—		0.1		0.3		0.3

Performance Contingent Cash Awards—A summary of the performance contingent cash awards activity for the nine months ended Sep. 30 was as follows:

	2011			2010
	Awards			Awards
Nonvested awards, Jan. 1		23,428			—
Granted		23,975			23,795
Forfeited		(727	)		(367	)
Nonvested awards, Sep. 30		46,676			23,428

IPL [Member]

Benefit Plans

(5) BENEFIT PLANS

(a) Pension and Other Postretirement Benefits Plans -

Net Periodic Benefit Costs—The components of Alliant Energy's, IPL's and WPL's net periodic benefit costs (credits) for their defined benefit pension and other postretirement benefits plans for the three and nine months ended Sep. 30 were as follows (in millions):

Alliant Energy	Defined Benefit Pension Plans												Other Postretirement Benefits Plans (a)
	Three Months						Nine Months						Three Months						Nine Months
	2011			2010			2011			2010			2011			2010			2011			2010
Service cost	$	2.9		$	3.0		$	8.6		$	9.0		$	1.6		$	2.2		$	5.4		$	7.0
Interest cost		13.0			13.1			39.0			39.3			2.8			3.5			9.5			11.4
Expected return on plan assets		(15.9	)		(15.6	)		(47.8	)		(46.6	)		(2.0	)		(1.9	)		(5.9	)		(5.8	)
Amortization of:
Transition obligation		—			—			—			—			—			—			—			0.1
Prior service cost (credit)		0.2			0.2			0.6			0.6			(3.4	)		(1.2	)		(6.6	)		(1.3	)
Actuarial loss		5.2			5.9			15.7			17.9			1.2			2.2			4.0			5.3
Additional benefit costs (b)		1.3			—			10.2			—			—			—			—			—
Settlement losses (c)		1.1			1.4			1.1			1.4			—			—			—			—
	$	7.8		$	8.0		$	27.4		$	21.6		$	0.2		$	4.8		$	6.4		$	16.7

	Qualified Defined Benefit Pension Plans												Other Postretirement Benefits Plans (a)
	Three Months						Nine Months						Three Months						Nine Months
IPL	2011			2010			2011			2010			2011			2010			2011			2010
Service cost	$	1.5		$	1.5		$	4.6		$	4.6		$	0.6		$	0.8		$	2.0		$	2.6
Interest cost		4.2			4.2			12.5			12.4			1.3			1.6			4.3			5.2
Expected return on plan assets		(5.0	)		(4.9	)		(15.0	)		(14.6	)		(1.4	)		(1.3	)		(4.0	)		(4.0	)
Amortization of:
Transition obligation		—			—			—			—			—			—			—			0.1
Prior service cost (credit)		0.2			0.2			0.4			0.5			(1.8	)		(0.5	)		(3.3	)		(0.6	)
Actuarial loss		1.4			1.8			4.3			5.4			0.7			1.2			2.2			2.8
	$	2.3		$	2.8		$	6.8		$	8.3		($	0.6	)	$	1.8		$	1.2		$	6.1

	Qualified Defined Benefit Pension Plan												Other Postretirement Benefits Plans (a)
	Three Months						Nine Months						Three Months						Nine Months
WPL	2011			2010			2011			2010			2011			2010			2011			2010
Service cost	$	1.1		$	1.2		$	3.4		$	3.6		$	0.7		$	0.9		$	2.2		$	2.7
Interest cost		4.1			3.9			12.1			11.8			1.1			1.3			3.7			4.2
Expected return on plan assets		(5.0	)		(4.8	)		(15.0	)		(14.3	)		(0.3	)		(0.4	)		(1.0	)		(1.0	)
Amortization of:
Prior service cost (credit)		0.1			0.2			0.4			0.4			(1.1	)		(0.2	)		(2.2	)		(0.2	)
Actuarial loss		1.8			2.2			5.3			6.4			0.5			0.7			1.6			1.7
	$	2.1		$	2.7		$	6.2		$	7.9		$	0.9		$	2.3		$	4.3		$	7.4

(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 remeasurement resulted in a decrease in Alliant Energy's postretirement benefit obligations of $64 million ($38 million for IPL, $16 million for WPL and $10 million for Corporate Services) 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 $4.3 million, $2.7 million and $1.4 million during the three months ended Sep. 30, 2011, respectively, and $7.1 million, $4.5 million, and $2.4 million during the nine months ended Sep. 30, 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) Alliant Energy reached an agreement with the IRS, which resulted in a favorable determination letter for the Alliant Energy Cash Balance Pension Plan (Plan) during the first quarter of 2011. The agreement with the IRS required Alliant Energy to amend the Plan, which was completed in the second quarter of 2011 resulting in aggregate additional benefits of $10.2 million to be paid to certain former participants in the Plan in the second half of 2011. Alliant Energy recognized $1.3 million and $10.2 million of additional benefits costs during the three and nine months ended Sep. 30, 2011, respectively, related to these benefits. Refer to Note 11(c) for additional information regarding the Plan.

(c) For both the three and nine months ended Sep. 30, 2011 and 2010, settlement losses of $1.1 million and $1.4 million, respectively, related to payments made to retired executives.

In the above tables for IPL and WPL, 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. The other postretirement benefits costs represent costs for all IPL and WPL employees. Corporate Services provides services to IPL and WPL, and as a result, IPL and WPL are allocated pension and other postretirement benefits costs (credits) associated with Corporate Services employees. The following table includes qualified pension benefits costs for IPL's and WPL's non-bargaining employees who are participants in other Alliant Energy plans, and the allocated qualified pension and other postretirement benefits costs (credits) associated with Corporate Services employees providing services to IPL and WPL for the three and nine months ended Sep. 30 (in millions):

	Qualified Pension Benefits Costs (a)								Other Postretirement Benefits Costs (Credits)
	Three Months				Nine Months				Three Months					Nine Months
	2011		2010		2011		2010		2011			2010		2011		2010
IPL	$	0.7	$	—	$	6.0	$	—	$	—		$	0.4	$	0.4	$	1.7
WPL		0.5		0.1		3.8		0.5		(0.1	)		0.3		0.2		1.1

(a) For the three and nine months ended Sep. 30, 2011, additional qualified pension benefits costs resulting from the second quarter 2011 amendment to the Cash Balance Pension Plan allocated to IPL were $0.8 million and $6.3 million, respectively, and to WPL were $0.4 million and $3.4 million, respectively.

Alliant Energy sponsors several non-qualified defined benefit pension plans that cover certain current and former key employees. The pension costs allocated to IPL and WPL for these plans for the three and nine months ended Sep. 30 were as follows (in millions):

	IPL								WPL
	Three Months				Nine Months				Three Months				Nine Months
	2011		2010		2011		2010		2011		2010		2011		2010
Pension costs	$	1.3	$	1.5	$	2.5	$	3.0	$	0.8	$	1.0	$	1.5	$	1.8

Estimated Future and Actual Employer Contributions—Alliant Energy's, IPL's, and WPL's estimated and actual funding for the qualified defined benefit pension, non-qualified defined benefit pension and other postretirement benefits plans for 2011 are as follows (in millions):

	Estimated for Calendar Year 2011								Actual Through Sep. 30, 2011
	Alliant Energy		IPL			WPL			Alliant Energy		IPL			WPL
Qualified defined benefit pension plans	$	10	$	—		$	—		$	9	$	—		$	—
Non-qualified defined benefit pension plans		7		(a	)		(a	)		6		(a	)		(a	)
Other postretirement benefits plans		9		3			5			7		2			4

(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.

Alliant Energy Cash Balance Pension Plan (Plan)—Refer to Note 11(c) for discussion of a class action lawsuit filed against the 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). For the three and nine months ended Sep. 30, 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 (a)								WPL (a)
	Three Months				Nine Months				Three Months				Nine Months				Three Months				Nine Months
	2011		2010		2011		2010		2011		2010		2011		2010		2011		2010		2011		2010
401(k) costs	$	4.5	$	4.4	$	14.5	$	13.9	$	2.2	$	2.1	$	7.1	$	6.6	$	2.0	$	2.2	$	6.6	$	6.8

(a) IPL's and WPL's amounts include allocated costs associated with Corporate Services employees.

(b) Equity Incentive Plans—A summary of compensation expense and the related income tax benefits recognized for share-based compensation awards for the three and nine months ended Sep. 30 was as follows (in millions):

	Alliant Energy								IPL								WPL
	Three Months				Nine Months				Three Months				Nine Months				Three Months				Nine Months
	2011		2010		2011		2010		2011		2010		2011		2010		2011		2010		2011		2010
Compensation expense		$0.1	$	2.6		$4.9	$	6.2		$0.1	$	1.4		$2.7	$	3.3		$0.1	$	1.1		$2.0	$	2.5
Income tax benefits		0.1		1.1		2.0		2.5		0.1		0.5		1.1		1.3		—		0.4		0.8		1.0

As of Sep. 30, 2011, total unrecognized compensation cost related to share-based compensation awards was $12.9 million, which is expected to be recognized over a weighted average period of 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 Condensed Consolidated Statements of Income.

Performance Shares and Units—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—A summary of the performance shares activity for the nine months ended Sep. 30 was as follows:

	2011			2010
	Shares (a)			Shares (a)
Nonvested shares, Jan. 1		234,518			256,579
Granted		64,217			72,487
Vested (b)		(57,838	)		—
Forfeited (c)		(3,918	)		(83,786	)
Nonvested shares, Sep. 30		236,979			245,280

(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 the first quarter of 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).

(c) In the first quarter of 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 the nine months ended Sep. 30, 2011 and 2010 were primarily caused by retirements and voluntary terminations of participants.

Performance Units—A summary of the performance unit activity for the nine months ended Sep. 30 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, Sep. 30		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 Sep. 30, 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 Sep. 30, 2011	$	38.68		$	38.68		$	38.68
Alliant Energy common stock average price on grant date										$	38.75		$	32.56
Estimated payout percentage based on performance criteria		97	%		133	%		131	%		97	%		133	%
Fair values of each nonvested award	$	37.52		$	51.44		$	50.67		$	37.59		$	43.30

At Sep. 30, 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 group. 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 consists of time-based and performance-contingent restricted stock.

Time-based restricted stock—A summary of the time-based restricted stock activity for the nine months ended Sep. 30 was as follows:

	2011					2010
	Shares			Weighted Average Fair Value		Shares			Weighted Average Fair Value
Nonvested shares, Jan. 1		70,033		$	32.27		125,349		$	32.47
Granted during first quarter		5,000			39.86		—			—
Vested		(38,633	)		34.60		(51,736	)		32.87
Forfeited		(600	)		29.41		(1,300	)		32.78
Nonvested shares, Sep. 30		35,800			30.87		72,313			32.18

Performance-contingent restricted stock—A summary of the performance-contingent restricted stock activity for the nine months ended Sep. 30 was as follows:

	2011					2010
	Shares			Weighted Average Fair Value		Shares			Weighted Average Fair Value
Nonvested shares, Jan. 1		296,190		$	32.32		226,007		$	32.25
Granted during first quarter		64,217			38.75		72,487			32.56
Vested		(53,274	)		37.93		—			—
Forfeited		(5,395	)		38.00		(2,304	)		32.56
Nonvested shares, Sep. 30		301,738			32.60		296,190			32.32

Non-qualified Stock Options—A summary of the stock option activity for the nine months ended Sep. 30 was as follows:

	2011					2010
	Shares			Weighted Average Exercise Price		Shares			Weighted Average Exercise Price
Outstanding, Jan. 1		163,680		$	24.51		384,331		$	27.02
Exercised		(62,481	)		27.10		(151,693	)		28.34
Expired		—			—		(29,218	)		28.59
Outstanding and exercisable, Sep. 30		101,199			22.92		203,420			25.81

The weighted average remaining contractual term for options outstanding and exercisable at Sep. 30, 2011 was between one and two years. The aggregate intrinsic value of options outstanding and exercisable at Sep. 30, 2011 was $1.6 million.

Other information related to stock option activity for the three and nine months ended Sep. 30 was as follows (in millions):

	Three Months				Nine Months
	2011		2010		2011		2010
Cash received from stock options exercised	$	0.1	$	2.0	$	1.7	$	4.3
Aggregate intrinsic value of stock options exercised		—		0.4		0.8		0.9
Income tax benefit from the exercise of stock options		—		0.1		0.3		0.3

Performance Contingent Cash Awards—A summary of the performance contingent cash awards activity for the nine months ended Sep. 30 was as follows:

	2011			2010
	Awards			Awards
Nonvested awards, Jan. 1		23,428			—
Granted		23,975			23,795
Forfeited		(727	)		(367	)
Nonvested awards, Sep. 30		46,676			23,428

WPL [Member]

Benefit Plans

(5) BENEFIT PLANS

(a) Pension and Other Postretirement Benefits Plans -

Net Periodic Benefit Costs—The components of Alliant Energy's, IPL's and WPL's net periodic benefit costs (credits) for their defined benefit pension and other postretirement benefits plans for the three and nine months ended Sep. 30 were as follows (in millions):

Alliant Energy	Defined Benefit Pension Plans												Other Postretirement Benefits Plans (a)
	Three Months						Nine Months						Three Months						Nine Months
	2011			2010			2011			2010			2011			2010			2011			2010
Service cost	$	2.9		$	3.0		$	8.6		$	9.0		$	1.6		$	2.2		$	5.4		$	7.0
Interest cost		13.0			13.1			39.0			39.3			2.8			3.5			9.5			11.4
Expected return on plan assets		(15.9	)		(15.6	)		(47.8	)		(46.6	)		(2.0	)		(1.9	)		(5.9	)		(5.8	)
Amortization of:
Transition obligation		—			—			—			—			—			—			—			0.1
Prior service cost (credit)		0.2			0.2			0.6			0.6			(3.4	)		(1.2	)		(6.6	)		(1.3	)
Actuarial loss		5.2			5.9			15.7			17.9			1.2			2.2			4.0			5.3
Additional benefit costs (b)		1.3			—			10.2			—			—			—			—			—
Settlement losses (c)		1.1			1.4			1.1			1.4			—			—			—			—
	$	7.8		$	8.0		$	27.4		$	21.6		$	0.2		$	4.8		$	6.4		$	16.7

	Qualified Defined Benefit Pension Plans												Other Postretirement Benefits Plans (a)
	Three Months						Nine Months						Three Months						Nine Months
IPL	2011			2010			2011			2010			2011			2010			2011			2010
Service cost	$	1.5		$	1.5		$	4.6		$	4.6		$	0.6		$	0.8		$	2.0		$	2.6
Interest cost		4.2			4.2			12.5			12.4			1.3			1.6			4.3			5.2
Expected return on plan assets		(5.0	)		(4.9	)		(15.0	)		(14.6	)		(1.4	)		(1.3	)		(4.0	)		(4.0	)
Amortization of:
Transition obligation		—			—			—			—			—			—			—			0.1
Prior service cost (credit)		0.2			0.2			0.4			0.5			(1.8	)		(0.5	)		(3.3	)		(0.6	)
Actuarial loss		1.4			1.8			4.3			5.4			0.7			1.2			2.2			2.8
	$	2.3		$	2.8		$	6.8		$	8.3		($	0.6	)	$	1.8		$	1.2		$	6.1

	Qualified Defined Benefit Pension Plan												Other Postretirement Benefits Plans (a)
	Three Months						Nine Months						Three Months						Nine Months
WPL	2011			2010			2011			2010			2011			2010			2011			2010
Service cost	$	1.1		$	1.2		$	3.4		$	3.6		$	0.7		$	0.9		$	2.2		$	2.7
Interest cost		4.1			3.9			12.1			11.8			1.1			1.3			3.7			4.2
Expected return on plan assets		(5.0	)		(4.8	)		(15.0	)		(14.3	)		(0.3	)		(0.4	)		(1.0	)		(1.0	)
Amortization of:
Prior service cost (credit)		0.1			0.2			0.4			0.4			(1.1	)		(0.2	)		(2.2	)		(0.2	)
Actuarial loss		1.8			2.2			5.3			6.4			0.5			0.7			1.6			1.7
	$	2.1		$	2.7		$	6.2		$	7.9		$	0.9		$	2.3		$	4.3		$	7.4

(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 remeasurement resulted in a decrease in Alliant Energy's postretirement benefit obligations of $64 million ($38 million for IPL, $16 million for WPL and $10 million for Corporate Services) 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 $4.3 million, $2.7 million and $1.4 million during the three months ended Sep. 30, 2011, respectively, and $7.1 million, $4.5 million, and $2.4 million during the nine months ended Sep. 30, 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) Alliant Energy reached an agreement with the IRS, which resulted in a favorable determination letter for the Alliant Energy Cash Balance Pension Plan (Plan) during the first quarter of 2011. The agreement with the IRS required Alliant Energy to amend the Plan, which was completed in the second quarter of 2011 resulting in aggregate additional benefits of $10.2 million to be paid to certain former participants in the Plan in the second half of 2011. Alliant Energy recognized $1.3 million and $10.2 million of additional benefits costs during the three and nine months ended Sep. 30, 2011, respectively, related to these benefits. Refer to Note 11(c) for additional information regarding the Plan.

(c) For both the three and nine months ended Sep. 30, 2011 and 2010, settlement losses of $1.1 million and $1.4 million, respectively, related to payments made to retired executives.

In the above tables for IPL and WPL, 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. The other postretirement benefits costs represent costs for all IPL and WPL employees. Corporate Services provides services to IPL and WPL, and as a result, IPL and WPL are allocated pension and other postretirement benefits costs (credits) associated with Corporate Services employees. The following table includes qualified pension benefits costs for IPL's and WPL's non-bargaining employees who are participants in other Alliant Energy plans, and the allocated qualified pension and other postretirement benefits costs (credits) associated with Corporate Services employees providing services to IPL and WPL for the three and nine months ended Sep. 30 (in millions):

	Qualified Pension Benefits Costs (a)								Other Postretirement Benefits Costs (Credits)
	Three Months				Nine Months				Three Months					Nine Months
	2011		2010		2011		2010		2011			2010		2011		2010
IPL	$	0.7	$	—	$	6.0	$	—	$	—		$	0.4	$	0.4	$	1.7
WPL		0.5		0.1		3.8		0.5		(0.1	)		0.3		0.2		1.1

(a) For the three and nine months ended Sep. 30, 2011, additional qualified pension benefits costs resulting from the second quarter 2011 amendment to the Cash Balance Pension Plan allocated to IPL were $0.8 million and $6.3 million, respectively, and to WPL were $0.4 million and $3.4 million, respectively.

Alliant Energy sponsors several non-qualified defined benefit pension plans that cover certain current and former key employees. The pension costs allocated to IPL and WPL for these plans for the three and nine months ended Sep. 30 were as follows (in millions):

	IPL								WPL
	Three Months				Nine Months				Three Months				Nine Months
	2011		2010		2011		2010		2011		2010		2011		2010
Pension costs	$	1.3	$	1.5	$	2.5	$	3.0	$	0.8	$	1.0	$	1.5	$	1.8

Estimated Future and Actual Employer Contributions—Alliant Energy's, IPL's, and WPL's estimated and actual funding for the qualified defined benefit pension, non-qualified defined benefit pension and other postretirement benefits plans for 2011 are as follows (in millions):

	Estimated for Calendar Year 2011								Actual Through Sep. 30, 2011
	Alliant Energy		IPL			WPL			Alliant Energy		IPL			WPL
Qualified defined benefit pension plans	$	10	$	—		$	—		$	9	$	—		$	—
Non-qualified defined benefit pension plans		7		(a	)		(a	)		6		(a	)		(a	)
Other postretirement benefits plans		9		3			5			7		2			4

(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.

Alliant Energy Cash Balance Pension Plan (Plan)—Refer to Note 11(c) for discussion of a class action lawsuit filed against the 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). For the three and nine months ended Sep. 30, 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 (a)								WPL (a)
	Three Months				Nine Months				Three Months				Nine Months				Three Months				Nine Months
	2011		2010		2011		2010		2011		2010		2011		2010		2011		2010		2011		2010
401(k) costs	$	4.5	$	4.4	$	14.5	$	13.9	$	2.2	$	2.1	$	7.1	$	6.6	$	2.0	$	2.2	$	6.6	$	6.8

(a) IPL's and WPL's amounts include allocated costs associated with Corporate Services employees.

(b) Equity Incentive Plans—A summary of compensation expense and the related income tax benefits recognized for share-based compensation awards for the three and nine months ended Sep. 30 was as follows (in millions):

	Alliant Energy								IPL								WPL
	Three Months				Nine Months				Three Months				Nine Months				Three Months				Nine Months
	2011		2010		2011		2010		2011		2010		2011		2010		2011		2010		2011		2010
Compensation expense		$0.1	$	2.6		$4.9	$	6.2		$0.1	$	1.4		$2.7	$	3.3		$0.1	$	1.1		$2.0	$	2.5
Income tax benefits		0.1		1.1		2.0		2.5		0.1		0.5		1.1		1.3		—		0.4		0.8		1.0

As of Sep. 30, 2011, total unrecognized compensation cost related to share-based compensation awards was $12.9 million, which is expected to be recognized over a weighted average period of 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 Condensed Consolidated Statements of Income.

Performance Shares and Units—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—A summary of the performance shares activity for the nine months ended Sep. 30 was as follows:

	2011			2010
	Shares (a)			Shares (a)
Nonvested shares, Jan. 1		234,518			256,579
Granted		64,217			72,487
Vested (b)		(57,838	)		—
Forfeited (c)		(3,918	)		(83,786	)
Nonvested shares, Sep. 30		236,979			245,280

(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 the first quarter of 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).

(c) In the first quarter of 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 the nine months ended Sep. 30, 2011 and 2010 were primarily caused by retirements and voluntary terminations of participants.

Performance Units—A summary of the performance unit activity for the nine months ended Sep. 30 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, Sep. 30		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 Sep. 30, 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 Sep. 30, 2011	$	38.68		$	38.68		$	38.68
Alliant Energy common stock average price on grant date										$	38.75		$	32.56
Estimated payout percentage based on performance criteria		97	%		133	%		131	%		97	%		133	%
Fair values of each nonvested award	$	37.52		$	51.44		$	50.67		$	37.59		$	43.30

At Sep. 30, 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 group. 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 consists of time-based and performance-contingent restricted stock.

Time-based restricted stock—A summary of the time-based restricted stock activity for the nine months ended Sep. 30 was as follows:

	2011					2010
	Shares			Weighted Average Fair Value		Shares			Weighted Average Fair Value
Nonvested shares, Jan. 1		70,033		$	32.27		125,349		$	32.47
Granted during first quarter		5,000			39.86		—			—
Vested		(38,633	)		34.60		(51,736	)		32.87
Forfeited		(600	)		29.41		(1,300	)		32.78
Nonvested shares, Sep. 30		35,800			30.87		72,313			32.18

Performance-contingent restricted stock—A summary of the performance-contingent restricted stock activity for the nine months ended Sep. 30 was as follows:

	2011					2010
	Shares			Weighted Average Fair Value		Shares			Weighted Average Fair Value
Nonvested shares, Jan. 1		296,190		$	32.32		226,007		$	32.25
Granted during first quarter		64,217			38.75		72,487			32.56
Vested		(53,274	)		37.93		—			—
Forfeited		(5,395	)		38.00		(2,304	)		32.56
Nonvested shares, Sep. 30		301,738			32.60		296,190			32.32

Non-qualified Stock Options—A summary of the stock option activity for the nine months ended Sep. 30 was as follows:

	2011					2010
	Shares			Weighted Average Exercise Price		Shares			Weighted Average Exercise Price
Outstanding, Jan. 1		163,680		$	24.51		384,331		$	27.02
Exercised		(62,481	)		27.10		(151,693	)		28.34
Expired		—			—		(29,218	)		28.59
Outstanding and exercisable, Sep. 30		101,199			22.92		203,420			25.81

The weighted average remaining contractual term for options outstanding and exercisable at Sep. 30, 2011 was between one and two years. The aggregate intrinsic value of options outstanding and exercisable at Sep. 30, 2011 was $1.6 million.

Other information related to stock option activity for the three and nine months ended Sep. 30 was as follows (in millions):

	Three Months				Nine Months
	2011		2010		2011		2010
Cash received from stock options exercised	$	0.1	$	2.0	$	1.7	$	4.3
Aggregate intrinsic value of stock options exercised		—		0.4		0.8		0.9
Income tax benefit from the exercise of stock options		—		0.1		0.3		0.3

Performance Contingent Cash Awards—A summary of the performance contingent cash awards activity for the nine months ended Sep. 30 was as follows:

	2011			2010
	Awards			Awards
Nonvested awards, Jan. 1		23,428			—
Granted		23,975			23,795
Forfeited		(727	)		(367	)
Nonvested awards, Sep. 30		46,676			23,428