Benefit Plans (Tables)

12 Months Ended

Dec. 31, 2021

Defined Benefit Plan Disclosure [Line Items]

Assumptions Used To Measure Benefit Plans

The assumptions for defined benefit pension and OPEB plans at the measurement date of December 31 were as follows:

	Defined Benefit Pension Plans									OPEB Plans
Alliant Energy	2021			2020			2019			2021	2020	2019
Discount rate for benefit obligations	2.91%			2.57%			3.48%			2.81%	2.31%	3.40%
Discount rate for net periodic cost	2.57%			3.48%			4.34%			2.31%	3.40%	4.24%
Expected rate of return on plan assets	7.10%			7.10%			7.60%			4.80%	4.50%	5.44%
Interest crediting rate for Alliant Energy Cash Balance Pension Plan	4.18%			4.76%			5.52%			N/A	N/A	N/A
Rate of compensation increase	3.30%	-	4.50%	3.65%	-	4.50%	3.65%	-	4.50%	N/A	N/A	N/A

	Qualified Defined Benefit Pension Plan			OPEB Plans
IPL	2021	2020	2019	2021	2020	2019
Discount rate for benefit obligations	2.94%	2.61%	3.51%	2.80%	2.28%	3.39%
Discount rate for net periodic cost	2.61%	3.51%	4.35%	2.28%	3.39%	4.23%
Expected rate of return on plan assets	7.10%	7.10%	7.60%	5.10%	4.50%	5.60%
Rate of compensation increase	3.30%	3.65%	3.65%	N/A	N/A	N/A

	Qualified Defined Benefit Pension Plan			OPEB Plans
WPL	2021	2020	2019	2021	2020	2019
Discount rate for benefit obligations	2.94%	2.64%	3.50%	2.79%	2.27%	3.39%
Discount rate for net periodic cost	2.64%	3.50%	4.35%	2.27%	3.39%	4.23%
Expected rate of return on plan assets	7.10%	7.10%	7.60%	4.02%	3.28%	3.81%
Rate of compensation increase	3.30%	3.65%	3.65%	N/A	N/A	N/A

Net Periodic Benefit Costs

The components of net periodic benefit costs for sponsored defined benefit pension and OPEB plans are included below (in millions). The service cost component of net periodic benefit costs is included in “Other operation and maintenance” expenses in the income statements and all other components of net periodic benefit costs are included in “Other (income) and deductions” in the income statements.

Alliant Energy	Defined Benefit Pension Plans			OPEB Plans
	2021	2020	2019	2021	2020	2019
Service cost	$11	$11	$10	$4	$3	$3
Interest cost	34	43	50	5	7	9
Expected return on plan assets (a)	(69)	(70)	(60)	(5)	(5)	(5)
Amortization of prior service credit (b)	—	—	(1)	—	—	—
Amortization of actuarial loss (c)	39	34	36	5	3	3
Settlement losses (d)	—	12	—	—	—	—
	$15	$30	$35	$9	$8	$10

IPL	Defined Benefit Pension Plans			OPEB Plans
	2021	2020	2019	2021	2020	2019
Service cost	$7	$7	$6	$1	$1	$1
Interest cost	16	20	23	2	3	3
Expected return on plan assets (a)	(32)	(33)	(28)	(3)	(4)	(4)
Amortization of actuarial loss (c)	17	15	15	2	1	2
Settlement losses (d)	—	7	—	—	—	—
	$8	$16	$16	$2	$1	$2

WPL	Defined Benefit Pension Plans			OPEB Plans
	2021	2020	2019	2021	2020	2019
Service cost	$4	$4	$3	$1	$2	$1
Interest cost	15	19	21	2	3	3
Expected return on plan assets (a)	(31)	(31)	(26)	—	(1)	(1)
Amortization of prior service credit (b)	—	—	—	—	(1)	—
Amortization of actuarial loss (c)	19	16	18	2	2	2
	$7	$8	$16	$5	$5	$5

(a)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.

(b)Unrecognized prior service credits for the OPEB plans are amortized over the average future service period to full eligibility of the participants of each plan.

(c)Unrecognized net actuarial gains or losses in excess of 10% of the greater of the plans’ benefit obligations or assets are amortized over the average future service lives of plan participants, except for the Alliant Energy Cash Balance Pension Plan where gains or losses outside the 10% threshold are amortized over the time period the participants are expected to receive benefits.

(d)Settlement losses related to payments made to retired executives of Alliant Energy and lump sum payments related to IPL’s qualified defined benefit pension plan.

Funded Status Of Benefit Plans

A reconciliation of the funded status of qualified and non-qualified defined benefit pension and OPEB plans to the amounts recognized on the balance sheets at December 31 was as follows (in millions):

	Defined Benefit Pension Plans		OPEB Plans
Alliant Energy	2021	2020	2021	2020
Change in benefit obligation:
Net benefit obligation at January 1	$1,351	$1,280	$227	$214
Service cost	11	11	4	3
Interest cost	34	43	5	7
Plan participants’ contributions	—	—	5	4
Actuarial (gain) loss	(46)	132	(12)	18
Gross benefits paid	(99)	(115)	(19)	(19)
Net benefit obligation at December 31	1,251	1,351	210	227
Change in plan assets:
Fair value of plan assets at January 1	984	931	108	105
Actual return on plan assets	87	108	4	11
Employer contributions	39	60	8	7
Plan participants’ contributions	—	—	5	4
Gross benefits paid	(99)	(115)	(19)	(19)
Fair value of plan assets at December 31	1,011	984	106	108
Under funded status at December 31	($240)	($367)	($104)	($119)

	Defined Benefit Pension Plans		OPEB Plans
Alliant Energy	2021	2020	2021	2020
Amounts recognized on the balance sheets consist of:
Non-current assets	$—	$—	$13	$8
Current liabilities	(2)	(2)	(8)	(8)
Pension and other benefit obligations	(238)	(365)	(109)	(119)
Net amounts recognized at December 31	($240)	($367)	($104)	($119)
Amounts recognized in Regulatory Assets consist of:
Net actuarial loss	$429	$533	$38	$54
Prior service credit	(4)	(5)	(1)	(1)
	$425	$528	$37	$53

	Defined Benefit Pension Plans		OPEB Plans
IPL	2021	2020	2021	2020
Change in benefit obligation:
Net benefit obligation at January 1	$615	$581	$91	$86
Service cost	7	7	1	1
Interest cost	16	20	2	3
Plan participants’ contributions	—	—	2	1
Actuarial (gain) loss	(23)	60	(4)	8
Gross benefits paid	(48)	(53)	(8)	(8)
Net benefit obligation at December 31	567	615	84	91
Change in plan assets:
Fair value of plan assets at January 1	453	436	74	72
Actual return on plan assets	40	51	4	7
Employer contributions	17	19	2	2
Plan participants’ contributions	—	—	2	1
Gross benefits paid	(48)	(53)	(8)	(8)
Fair value of plan assets at December 31	462	453	74	74
Under funded status at December 31	($105)	($162)	($10)	($17)

	Defined Benefit Pension Plans		OPEB Plans
IPL	2021	2020	2021	2020
Amounts recognized on the balance sheets consist of:
Non-current assets	$—	$—	$10	$4
Current liabilities	—	(1)	(2)	(2)
Pension and other benefit obligations	(105)	(161)	(18)	(19)
Net amounts recognized at December 31	($105)	($162)	($10)	($17)
Amounts recognized in Regulatory Assets consist of:
Net actuarial loss	$180	$228	$13	$20
Prior service credit	(1)	(1)	—	—
	$179	$227	$13	$20

	Defined Benefit Pension Plans		OPEB Plans
WPL	2021	2020	2021	2020
Change in benefit obligation:
Net benefit obligation at January 1	$588	$550	$89	$85
Service cost	4	4	1	2
Interest cost	15	19	2	3
Plan participants’ contributions	—	—	2	2
Actuarial (gain) loss	(18)	55	(5)	5
Gross benefits paid	(43)	(40)	(8)	(8)
Net benefit obligation at December 31	546	588	81	89
Change in plan assets:
Fair value of plan assets at January 1	436	406	18	17
Actual return on plan assets	39	48	—	2
Employer contributions	18	22	5	5
Plan participants’ contributions	—	—	2	2
Gross benefits paid	(43)	(40)	(8)	(8)
Fair value of plan assets at December 31	450	436	17	18
Under funded status at December 31	($96)	($152)	($64)	($71)

	Defined Benefit Pension Plans		OPEB Plans
WPL	2021	2020	2021	2020
Amounts recognized on the balance sheets consist of:
Non-current assets	$—	$—	$3	$3
Current liabilities	—	—	(6)	(6)
Pension and other benefit obligations	(96)	(152)	(61)	(68)
Net amounts recognized at December 31	($96)	($152)	($64)	($71)
Amounts recognized in Regulatory Assets consist of:
Net actuarial loss	$188	$233	$18	$25
Prior service credit	(1)	(1)	(1)	(1)
	$187	$232	$17	$24

Accumulated Benefit Obligations

Accumulated benefit obligations, aggregate amounts applicable to defined benefit pension and OPEB 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 December 31 measurement date are as follows (in millions):

	Defined Benefit Pension Plans		OPEB Plans
Alliant Energy	2021	2020	2021	2020
Accumulated benefit obligations	$1,214	$1,305	$210	$227
Plans with accumulated benefit obligations in excess of plan assets:
Accumulated benefit obligations	1,214	1,305	210	227
Fair value of plan assets	1,011	984	106	108
Plans with projected benefit obligations in excess of plan assets:
Projected benefit obligations	1,251	1,351	N/A	N/A
Fair value of plan assets	1,011	984	N/A	N/A

	Defined Benefit Pension Plans		OPEB Plans
IPL	2021	2020	2021	2020
Accumulated benefit obligations	$546	$589	$84	$91
Plans with accumulated benefit obligations in excess of plan assets:
Accumulated benefit obligations	546	589	84	91
Fair value of plan assets	462	453	74	74
Plans with projected benefit obligations in excess of plan assets:
Projected benefit obligations	567	615	N/A	N/A
Fair value of plan assets	462	453	N/A	N/A

	Defined Benefit Pension Plans		OPEB Plans
WPL	2021	2020	2021	2020
Accumulated benefit obligations	$532	$573	$81	$89
Plans with accumulated benefit obligations in excess of plan assets:
Accumulated benefit obligations	532	573	81	89
Fair value of plan assets	450	436	17	18
Plans with projected benefit obligations in excess of plan assets:
Projected benefit obligations	546	588	N/A	N/A
Fair value of plan assets	450	436	N/A	N/A

Regulatory Assets

In addition to the amounts recognized in regulatory assets in the above tables for IPL and WPL, regulatory assets 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 December 31 as follows (in millions):

	IPL		WPL
	2021	2020	2021	2020
Regulatory assets	$35	$44	$30	$34

Estimated Future Employer Contributions

Estimated funding for the qualified and non-qualified defined benefit pension and OPEB plans for 2022 is as follows (in millions):

	Alliant Energy	IPL	WPL
Defined benefit pension plans (a)	$2	$—	$—
OPEB plans	8	2	6

(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. In addition, IPL and WPL amounts reflect funding for their non-bargaining employees who are participants in the Alliant Energy and Corporate Services sponsored qualified and non-qualified defined benefit pension plans.

Expected Benefit Payments

Expected benefit payments for the qualified and non-qualified defined benefit plans, which reflect expected future service, as appropriate, are as follows (in millions):

Alliant Energy	2022	2023	2024	2025	2026	2027 - 2031
Defined benefit pension benefits	$85	$83	$82	$82	$83	$387
OPEB	18	17	17	17	16	71
	$103	$100	$99	$99	$99	$458

IPL	2022	2023	2024	2025	2026	2027 - 2031
Defined benefit pension benefits	$41	$40	$39	$39	$38	$174
OPEB	7	7	7	7	7	28
	$48	$47	$46	$46	$45	$202

WPL	2022	2023	2024	2025	2026	2027 - 2031
Defined benefit pension benefits	$37	$36	$35	$35	$34	$163
OPEB	7	7	7	7	6	27
	$44	$43	$42	$42	$40	$190

Recognized Compensation Expense And Income Tax Benefits

A summary of compensation expense, including amounts allocated to IPL and WPL, and the related income tax benefits recognized for share-based compensation awards was as follows (in millions):

	Alliant Energy			IPL			WPL
	2021	2020	2019	2021	2020	2019	2021	2020	2019
Compensation expense	$14	$16	$26	$8	$9	$15	$6	$6	$10
Income tax benefits	4	4	7	2	2	4	2	2	3

Schedule of Carrying Value and Fair Market Value of the Deferred Compensation Obligation

At December 31, the carrying value of the deferred compensation obligation for the company stock account 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):

	2021	2020
Carrying value	$12	$11
Fair market value	24	20

IPL [Member]

Defined Benefit Plan Disclosure [Line Items]

Assumptions Used To Measure Benefit Plans

The assumptions for defined benefit pension and OPEB plans at the measurement date of December 31 were as follows:

	Defined Benefit Pension Plans									OPEB Plans
Alliant Energy	2021			2020			2019			2021	2020	2019
Discount rate for benefit obligations	2.91%			2.57%			3.48%			2.81%	2.31%	3.40%
Discount rate for net periodic cost	2.57%			3.48%			4.34%			2.31%	3.40%	4.24%
Expected rate of return on plan assets	7.10%			7.10%			7.60%			4.80%	4.50%	5.44%
Interest crediting rate for Alliant Energy Cash Balance Pension Plan	4.18%			4.76%			5.52%			N/A	N/A	N/A
Rate of compensation increase	3.30%	-	4.50%	3.65%	-	4.50%	3.65%	-	4.50%	N/A	N/A	N/A

	Qualified Defined Benefit Pension Plan			OPEB Plans
IPL	2021	2020	2019	2021	2020	2019
Discount rate for benefit obligations	2.94%	2.61%	3.51%	2.80%	2.28%	3.39%
Discount rate for net periodic cost	2.61%	3.51%	4.35%	2.28%	3.39%	4.23%
Expected rate of return on plan assets	7.10%	7.10%	7.60%	5.10%	4.50%	5.60%
Rate of compensation increase	3.30%	3.65%	3.65%	N/A	N/A	N/A

	Qualified Defined Benefit Pension Plan			OPEB Plans
WPL	2021	2020	2019	2021	2020	2019
Discount rate for benefit obligations	2.94%	2.64%	3.50%	2.79%	2.27%	3.39%
Discount rate for net periodic cost	2.64%	3.50%	4.35%	2.27%	3.39%	4.23%
Expected rate of return on plan assets	7.10%	7.10%	7.60%	4.02%	3.28%	3.81%
Rate of compensation increase	3.30%	3.65%	3.65%	N/A	N/A	N/A

Net Periodic Benefit Costs

The components of net periodic benefit costs for sponsored defined benefit pension and OPEB plans are included below (in millions). The service cost component of net periodic benefit costs is included in “Other operation and maintenance” expenses in the income statements and all other components of net periodic benefit costs are included in “Other (income) and deductions” in the income statements.

Alliant Energy	Defined Benefit Pension Plans			OPEB Plans
	2021	2020	2019	2021	2020	2019
Service cost	$11	$11	$10	$4	$3	$3
Interest cost	34	43	50	5	7	9
Expected return on plan assets (a)	(69)	(70)	(60)	(5)	(5)	(5)
Amortization of prior service credit (b)	—	—	(1)	—	—	—
Amortization of actuarial loss (c)	39	34	36	5	3	3
Settlement losses (d)	—	12	—	—	—	—
	$15	$30	$35	$9	$8	$10

IPL	Defined Benefit Pension Plans			OPEB Plans
	2021	2020	2019	2021	2020	2019
Service cost	$7	$7	$6	$1	$1	$1
Interest cost	16	20	23	2	3	3
Expected return on plan assets (a)	(32)	(33)	(28)	(3)	(4)	(4)
Amortization of actuarial loss (c)	17	15	15	2	1	2
Settlement losses (d)	—	7	—	—	—	—
	$8	$16	$16	$2	$1	$2

WPL	Defined Benefit Pension Plans			OPEB Plans
	2021	2020	2019	2021	2020	2019
Service cost	$4	$4	$3	$1	$2	$1
Interest cost	15	19	21	2	3	3
Expected return on plan assets (a)	(31)	(31)	(26)	—	(1)	(1)
Amortization of prior service credit (b)	—	—	—	—	(1)	—
Amortization of actuarial loss (c)	19	16	18	2	2	2
	$7	$8	$16	$5	$5	$5

(a)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.

(b)Unrecognized prior service credits for the OPEB plans are amortized over the average future service period to full eligibility of the participants of each plan.

(c)Unrecognized net actuarial gains or losses in excess of 10% of the greater of the plans’ benefit obligations or assets are amortized over the average future service lives of plan participants, except for the Alliant Energy Cash Balance Pension Plan where gains or losses outside the 10% threshold are amortized over the time period the participants are expected to receive benefits.

(d)Settlement losses related to payments made to retired executives of Alliant Energy and lump sum payments related to IPL’s qualified defined benefit pension plan.

Funded Status Of Benefit Plans

A reconciliation of the funded status of qualified and non-qualified defined benefit pension and OPEB plans to the amounts recognized on the balance sheets at December 31 was as follows (in millions):

	Defined Benefit Pension Plans		OPEB Plans
Alliant Energy	2021	2020	2021	2020
Change in benefit obligation:
Net benefit obligation at January 1	$1,351	$1,280	$227	$214
Service cost	11	11	4	3
Interest cost	34	43	5	7
Plan participants’ contributions	—	—	5	4
Actuarial (gain) loss	(46)	132	(12)	18
Gross benefits paid	(99)	(115)	(19)	(19)
Net benefit obligation at December 31	1,251	1,351	210	227
Change in plan assets:
Fair value of plan assets at January 1	984	931	108	105
Actual return on plan assets	87	108	4	11
Employer contributions	39	60	8	7
Plan participants’ contributions	—	—	5	4
Gross benefits paid	(99)	(115)	(19)	(19)
Fair value of plan assets at December 31	1,011	984	106	108
Under funded status at December 31	($240)	($367)	($104)	($119)

	Defined Benefit Pension Plans		OPEB Plans
Alliant Energy	2021	2020	2021	2020
Amounts recognized on the balance sheets consist of:
Non-current assets	$—	$—	$13	$8
Current liabilities	(2)	(2)	(8)	(8)
Pension and other benefit obligations	(238)	(365)	(109)	(119)
Net amounts recognized at December 31	($240)	($367)	($104)	($119)
Amounts recognized in Regulatory Assets consist of:
Net actuarial loss	$429	$533	$38	$54
Prior service credit	(4)	(5)	(1)	(1)
	$425	$528	$37	$53

	Defined Benefit Pension Plans		OPEB Plans
IPL	2021	2020	2021	2020
Change in benefit obligation:
Net benefit obligation at January 1	$615	$581	$91	$86
Service cost	7	7	1	1
Interest cost	16	20	2	3
Plan participants’ contributions	—	—	2	1
Actuarial (gain) loss	(23)	60	(4)	8
Gross benefits paid	(48)	(53)	(8)	(8)
Net benefit obligation at December 31	567	615	84	91
Change in plan assets:
Fair value of plan assets at January 1	453	436	74	72
Actual return on plan assets	40	51	4	7
Employer contributions	17	19	2	2
Plan participants’ contributions	—	—	2	1
Gross benefits paid	(48)	(53)	(8)	(8)
Fair value of plan assets at December 31	462	453	74	74
Under funded status at December 31	($105)	($162)	($10)	($17)

	Defined Benefit Pension Plans		OPEB Plans
IPL	2021	2020	2021	2020
Amounts recognized on the balance sheets consist of:
Non-current assets	$—	$—	$10	$4
Current liabilities	—	(1)	(2)	(2)
Pension and other benefit obligations	(105)	(161)	(18)	(19)
Net amounts recognized at December 31	($105)	($162)	($10)	($17)
Amounts recognized in Regulatory Assets consist of:
Net actuarial loss	$180	$228	$13	$20
Prior service credit	(1)	(1)	—	—
	$179	$227	$13	$20

	Defined Benefit Pension Plans		OPEB Plans
WPL	2021	2020	2021	2020
Change in benefit obligation:
Net benefit obligation at January 1	$588	$550	$89	$85
Service cost	4	4	1	2
Interest cost	15	19	2	3
Plan participants’ contributions	—	—	2	2
Actuarial (gain) loss	(18)	55	(5)	5
Gross benefits paid	(43)	(40)	(8)	(8)
Net benefit obligation at December 31	546	588	81	89
Change in plan assets:
Fair value of plan assets at January 1	436	406	18	17
Actual return on plan assets	39	48	—	2
Employer contributions	18	22	5	5
Plan participants’ contributions	—	—	2	2
Gross benefits paid	(43)	(40)	(8)	(8)
Fair value of plan assets at December 31	450	436	17	18
Under funded status at December 31	($96)	($152)	($64)	($71)

	Defined Benefit Pension Plans		OPEB Plans
WPL	2021	2020	2021	2020
Amounts recognized on the balance sheets consist of:
Non-current assets	$—	$—	$3	$3
Current liabilities	—	—	(6)	(6)
Pension and other benefit obligations	(96)	(152)	(61)	(68)
Net amounts recognized at December 31	($96)	($152)	($64)	($71)
Amounts recognized in Regulatory Assets consist of:
Net actuarial loss	$188	$233	$18	$25
Prior service credit	(1)	(1)	(1)	(1)
	$187	$232	$17	$24

Accumulated Benefit Obligations

Accumulated benefit obligations, aggregate amounts applicable to defined benefit pension and OPEB 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 December 31 measurement date are as follows (in millions):

	Defined Benefit Pension Plans		OPEB Plans
Alliant Energy	2021	2020	2021	2020
Accumulated benefit obligations	$1,214	$1,305	$210	$227
Plans with accumulated benefit obligations in excess of plan assets:
Accumulated benefit obligations	1,214	1,305	210	227
Fair value of plan assets	1,011	984	106	108
Plans with projected benefit obligations in excess of plan assets:
Projected benefit obligations	1,251	1,351	N/A	N/A
Fair value of plan assets	1,011	984	N/A	N/A

	Defined Benefit Pension Plans		OPEB Plans
IPL	2021	2020	2021	2020
Accumulated benefit obligations	$546	$589	$84	$91
Plans with accumulated benefit obligations in excess of plan assets:
Accumulated benefit obligations	546	589	84	91
Fair value of plan assets	462	453	74	74
Plans with projected benefit obligations in excess of plan assets:
Projected benefit obligations	567	615	N/A	N/A
Fair value of plan assets	462	453	N/A	N/A

	Defined Benefit Pension Plans		OPEB Plans
WPL	2021	2020	2021	2020
Accumulated benefit obligations	$532	$573	$81	$89
Plans with accumulated benefit obligations in excess of plan assets:
Accumulated benefit obligations	532	573	81	89
Fair value of plan assets	450	436	17	18
Plans with projected benefit obligations in excess of plan assets:
Projected benefit obligations	546	588	N/A	N/A
Fair value of plan assets	450	436	N/A	N/A

Regulatory Assets

In addition to the amounts recognized in regulatory assets in the above tables for IPL and WPL, regulatory assets 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 December 31 as follows (in millions):

	IPL		WPL
	2021	2020	2021	2020
Regulatory assets	$35	$44	$30	$34

Estimated Future Employer Contributions

Estimated funding for the qualified and non-qualified defined benefit pension and OPEB plans for 2022 is as follows (in millions):

	Alliant Energy	IPL	WPL
Defined benefit pension plans (a)	$2	$—	$—
OPEB plans	8	2	6

(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. In addition, IPL and WPL amounts reflect funding for their non-bargaining employees who are participants in the Alliant Energy and Corporate Services sponsored qualified and non-qualified defined benefit pension plans.

Expected Benefit Payments

Expected benefit payments for the qualified and non-qualified defined benefit plans, which reflect expected future service, as appropriate, are as follows (in millions):

Alliant Energy	2022	2023	2024	2025	2026	2027 - 2031
Defined benefit pension benefits	$85	$83	$82	$82	$83	$387
OPEB	18	17	17	17	16	71
	$103	$100	$99	$99	$99	$458

IPL	2022	2023	2024	2025	2026	2027 - 2031
Defined benefit pension benefits	$41	$40	$39	$39	$38	$174
OPEB	7	7	7	7	7	28
	$48	$47	$46	$46	$45	$202

WPL	2022	2023	2024	2025	2026	2027 - 2031
Defined benefit pension benefits	$37	$36	$35	$35	$34	$163
OPEB	7	7	7	7	6	27
	$44	$43	$42	$42	$40	$190

Recognized Compensation Expense And Income Tax Benefits

A summary of compensation expense, including amounts allocated to IPL and WPL, and the related income tax benefits recognized for share-based compensation awards was as follows (in millions):

	Alliant Energy			IPL			WPL
	2021	2020	2019	2021	2020	2019	2021	2020	2019
Compensation expense	$14	$16	$26	$8	$9	$15	$6	$6	$10
Income tax benefits	4	4	7	2	2	4	2	2	3

WPL [Member]

Defined Benefit Plan Disclosure [Line Items]

Assumptions Used To Measure Benefit Plans

The assumptions for defined benefit pension and OPEB plans at the measurement date of December 31 were as follows:

	Defined Benefit Pension Plans									OPEB Plans
Alliant Energy	2021			2020			2019			2021	2020	2019
Discount rate for benefit obligations	2.91%			2.57%			3.48%			2.81%	2.31%	3.40%
Discount rate for net periodic cost	2.57%			3.48%			4.34%			2.31%	3.40%	4.24%
Expected rate of return on plan assets	7.10%			7.10%			7.60%			4.80%	4.50%	5.44%
Interest crediting rate for Alliant Energy Cash Balance Pension Plan	4.18%			4.76%			5.52%			N/A	N/A	N/A
Rate of compensation increase	3.30%	-	4.50%	3.65%	-	4.50%	3.65%	-	4.50%	N/A	N/A	N/A

	Qualified Defined Benefit Pension Plan			OPEB Plans
IPL	2021	2020	2019	2021	2020	2019
Discount rate for benefit obligations	2.94%	2.61%	3.51%	2.80%	2.28%	3.39%
Discount rate for net periodic cost	2.61%	3.51%	4.35%	2.28%	3.39%	4.23%
Expected rate of return on plan assets	7.10%	7.10%	7.60%	5.10%	4.50%	5.60%
Rate of compensation increase	3.30%	3.65%	3.65%	N/A	N/A	N/A

	Qualified Defined Benefit Pension Plan			OPEB Plans
WPL	2021	2020	2019	2021	2020	2019
Discount rate for benefit obligations	2.94%	2.64%	3.50%	2.79%	2.27%	3.39%
Discount rate for net periodic cost	2.64%	3.50%	4.35%	2.27%	3.39%	4.23%
Expected rate of return on plan assets	7.10%	7.10%	7.60%	4.02%	3.28%	3.81%
Rate of compensation increase	3.30%	3.65%	3.65%	N/A	N/A	N/A

Net Periodic Benefit Costs

The components of net periodic benefit costs for sponsored defined benefit pension and OPEB plans are included below (in millions). The service cost component of net periodic benefit costs is included in “Other operation and maintenance” expenses in the income statements and all other components of net periodic benefit costs are included in “Other (income) and deductions” in the income statements.

Alliant Energy	Defined Benefit Pension Plans			OPEB Plans
	2021	2020	2019	2021	2020	2019
Service cost	$11	$11	$10	$4	$3	$3
Interest cost	34	43	50	5	7	9
Expected return on plan assets (a)	(69)	(70)	(60)	(5)	(5)	(5)
Amortization of prior service credit (b)	—	—	(1)	—	—	—
Amortization of actuarial loss (c)	39	34	36	5	3	3
Settlement losses (d)	—	12	—	—	—	—
	$15	$30	$35	$9	$8	$10

IPL	Defined Benefit Pension Plans			OPEB Plans
	2021	2020	2019	2021	2020	2019
Service cost	$7	$7	$6	$1	$1	$1
Interest cost	16	20	23	2	3	3
Expected return on plan assets (a)	(32)	(33)	(28)	(3)	(4)	(4)
Amortization of actuarial loss (c)	17	15	15	2	1	2
Settlement losses (d)	—	7	—	—	—	—
	$8	$16	$16	$2	$1	$2

WPL	Defined Benefit Pension Plans			OPEB Plans
	2021	2020	2019	2021	2020	2019
Service cost	$4	$4	$3	$1	$2	$1
Interest cost	15	19	21	2	3	3
Expected return on plan assets (a)	(31)	(31)	(26)	—	(1)	(1)
Amortization of prior service credit (b)	—	—	—	—	(1)	—
Amortization of actuarial loss (c)	19	16	18	2	2	2
	$7	$8	$16	$5	$5	$5

(a)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.

(b)Unrecognized prior service credits for the OPEB plans are amortized over the average future service period to full eligibility of the participants of each plan.

(c)Unrecognized net actuarial gains or losses in excess of 10% of the greater of the plans’ benefit obligations or assets are amortized over the average future service lives of plan participants, except for the Alliant Energy Cash Balance Pension Plan where gains or losses outside the 10% threshold are amortized over the time period the participants are expected to receive benefits.

(d)Settlement losses related to payments made to retired executives of Alliant Energy and lump sum payments related to IPL’s qualified defined benefit pension plan.

Funded Status Of Benefit Plans

A reconciliation of the funded status of qualified and non-qualified defined benefit pension and OPEB plans to the amounts recognized on the balance sheets at December 31 was as follows (in millions):

	Defined Benefit Pension Plans		OPEB Plans
Alliant Energy	2021	2020	2021	2020
Change in benefit obligation:
Net benefit obligation at January 1	$1,351	$1,280	$227	$214
Service cost	11	11	4	3
Interest cost	34	43	5	7
Plan participants’ contributions	—	—	5	4
Actuarial (gain) loss	(46)	132	(12)	18
Gross benefits paid	(99)	(115)	(19)	(19)
Net benefit obligation at December 31	1,251	1,351	210	227
Change in plan assets:
Fair value of plan assets at January 1	984	931	108	105
Actual return on plan assets	87	108	4	11
Employer contributions	39	60	8	7
Plan participants’ contributions	—	—	5	4
Gross benefits paid	(99)	(115)	(19)	(19)
Fair value of plan assets at December 31	1,011	984	106	108
Under funded status at December 31	($240)	($367)	($104)	($119)

	Defined Benefit Pension Plans		OPEB Plans
Alliant Energy	2021	2020	2021	2020
Amounts recognized on the balance sheets consist of:
Non-current assets	$—	$—	$13	$8
Current liabilities	(2)	(2)	(8)	(8)
Pension and other benefit obligations	(238)	(365)	(109)	(119)
Net amounts recognized at December 31	($240)	($367)	($104)	($119)
Amounts recognized in Regulatory Assets consist of:
Net actuarial loss	$429	$533	$38	$54
Prior service credit	(4)	(5)	(1)	(1)
	$425	$528	$37	$53

	Defined Benefit Pension Plans		OPEB Plans
IPL	2021	2020	2021	2020
Change in benefit obligation:
Net benefit obligation at January 1	$615	$581	$91	$86
Service cost	7	7	1	1
Interest cost	16	20	2	3
Plan participants’ contributions	—	—	2	1
Actuarial (gain) loss	(23)	60	(4)	8
Gross benefits paid	(48)	(53)	(8)	(8)
Net benefit obligation at December 31	567	615	84	91
Change in plan assets:
Fair value of plan assets at January 1	453	436	74	72
Actual return on plan assets	40	51	4	7
Employer contributions	17	19	2	2
Plan participants’ contributions	—	—	2	1
Gross benefits paid	(48)	(53)	(8)	(8)
Fair value of plan assets at December 31	462	453	74	74
Under funded status at December 31	($105)	($162)	($10)	($17)

	Defined Benefit Pension Plans		OPEB Plans
IPL	2021	2020	2021	2020
Amounts recognized on the balance sheets consist of:
Non-current assets	$—	$—	$10	$4
Current liabilities	—	(1)	(2)	(2)
Pension and other benefit obligations	(105)	(161)	(18)	(19)
Net amounts recognized at December 31	($105)	($162)	($10)	($17)
Amounts recognized in Regulatory Assets consist of:
Net actuarial loss	$180	$228	$13	$20
Prior service credit	(1)	(1)	—	—
	$179	$227	$13	$20

	Defined Benefit Pension Plans		OPEB Plans
WPL	2021	2020	2021	2020
Change in benefit obligation:
Net benefit obligation at January 1	$588	$550	$89	$85
Service cost	4	4	1	2
Interest cost	15	19	2	3
Plan participants’ contributions	—	—	2	2
Actuarial (gain) loss	(18)	55	(5)	5
Gross benefits paid	(43)	(40)	(8)	(8)
Net benefit obligation at December 31	546	588	81	89
Change in plan assets:
Fair value of plan assets at January 1	436	406	18	17
Actual return on plan assets	39	48	—	2
Employer contributions	18	22	5	5
Plan participants’ contributions	—	—	2	2
Gross benefits paid	(43)	(40)	(8)	(8)
Fair value of plan assets at December 31	450	436	17	18
Under funded status at December 31	($96)	($152)	($64)	($71)

	Defined Benefit Pension Plans		OPEB Plans
WPL	2021	2020	2021	2020
Amounts recognized on the balance sheets consist of:
Non-current assets	$—	$—	$3	$3
Current liabilities	—	—	(6)	(6)
Pension and other benefit obligations	(96)	(152)	(61)	(68)
Net amounts recognized at December 31	($96)	($152)	($64)	($71)
Amounts recognized in Regulatory Assets consist of:
Net actuarial loss	$188	$233	$18	$25
Prior service credit	(1)	(1)	(1)	(1)
	$187	$232	$17	$24

Accumulated Benefit Obligations

Accumulated benefit obligations, aggregate amounts applicable to defined benefit pension and OPEB 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 December 31 measurement date are as follows (in millions):

	Defined Benefit Pension Plans		OPEB Plans
Alliant Energy	2021	2020	2021	2020
Accumulated benefit obligations	$1,214	$1,305	$210	$227
Plans with accumulated benefit obligations in excess of plan assets:
Accumulated benefit obligations	1,214	1,305	210	227
Fair value of plan assets	1,011	984	106	108
Plans with projected benefit obligations in excess of plan assets:
Projected benefit obligations	1,251	1,351	N/A	N/A
Fair value of plan assets	1,011	984	N/A	N/A

	Defined Benefit Pension Plans		OPEB Plans
IPL	2021	2020	2021	2020
Accumulated benefit obligations	$546	$589	$84	$91
Plans with accumulated benefit obligations in excess of plan assets:
Accumulated benefit obligations	546	589	84	91
Fair value of plan assets	462	453	74	74
Plans with projected benefit obligations in excess of plan assets:
Projected benefit obligations	567	615	N/A	N/A
Fair value of plan assets	462	453	N/A	N/A

	Defined Benefit Pension Plans		OPEB Plans
WPL	2021	2020	2021	2020
Accumulated benefit obligations	$532	$573	$81	$89
Plans with accumulated benefit obligations in excess of plan assets:
Accumulated benefit obligations	532	573	81	89
Fair value of plan assets	450	436	17	18
Plans with projected benefit obligations in excess of plan assets:
Projected benefit obligations	546	588	N/A	N/A
Fair value of plan assets	450	436	N/A	N/A

Regulatory Assets

In addition to the amounts recognized in regulatory assets in the above tables for IPL and WPL, regulatory assets 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 December 31 as follows (in millions):

	IPL		WPL
	2021	2020	2021	2020
Regulatory assets	$35	$44	$30	$34

Estimated Future Employer Contributions

Estimated funding for the qualified and non-qualified defined benefit pension and OPEB plans for 2022 is as follows (in millions):

	Alliant Energy	IPL	WPL
Defined benefit pension plans (a)	$2	$—	$—
OPEB plans	8	2	6

(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. In addition, IPL and WPL amounts reflect funding for their non-bargaining employees who are participants in the Alliant Energy and Corporate Services sponsored qualified and non-qualified defined benefit pension plans.

Expected Benefit Payments

Expected benefit payments for the qualified and non-qualified defined benefit plans, which reflect expected future service, as appropriate, are as follows (in millions):

Alliant Energy	2022	2023	2024	2025	2026	2027 - 2031
Defined benefit pension benefits	$85	$83	$82	$82	$83	$387
OPEB	18	17	17	17	16	71
	$103	$100	$99	$99	$99	$458

IPL	2022	2023	2024	2025	2026	2027 - 2031
Defined benefit pension benefits	$41	$40	$39	$39	$38	$174
OPEB	7	7	7	7	7	28
	$48	$47	$46	$46	$45	$202

WPL	2022	2023	2024	2025	2026	2027 - 2031
Defined benefit pension benefits	$37	$36	$35	$35	$34	$163
OPEB	7	7	7	7	6	27
	$44	$43	$42	$42	$40	$190

Recognized Compensation Expense And Income Tax Benefits

A summary of compensation expense, including amounts allocated to IPL and WPL, and the related income tax benefits recognized for share-based compensation awards was as follows (in millions):

	Alliant Energy			IPL			WPL
	2021	2020	2019	2021	2020	2019	2021	2020	2019
Compensation expense	$14	$16	$26	$8	$9	$15	$6	$6	$10
Income tax benefits	4	4	7	2	2	4	2	2	3

Pension Plans, Defined Benefit [Member]

Defined Benefit Plan Disclosure [Line Items]

Fair Value Of Plan Assets By Asset Category, Fair Value Hierarchy Level and Allocations

At December 31, 2021, the current target ranges and actual allocations for the defined benefit pension plan assets were as follows:

	Target Range			Actual
	Allocation			Allocation
Cash and equivalents	0%	-	5%	3%
Equity securities - U.S.	14%	-	54%	34%
Equity securities - international	11%	-	31%	21%
Global asset securities	5%	-	15%	9%
Fixed income securities	25%	-	45%	33%

At December 31, the fair values of qualified and non-qualified defined benefit pension plan assets were as follows (in millions):

	2021				2020
	Fair	Level	Level	Level	Fair	Level	Level	Level
Alliant Energy	Value	1	2	3	Value	1	2	3
Cash and equivalents	$35	$—	$35	$—	$46	$—	$46	$—
Equity securities - U.S.	256	256	—	—	182	182	—	—
Equity securities - international	—	—	—	—	151	151	—	—
Global asset securities	52	52	—	—	45	45	—	—
Fixed income securities	191	47	144	—	134	56	78	—
Total assets in fair value hierarchy	534	$355	$179	$—	558	$434	$124	$—
Assets measured at net asset value	477				426
Accrued investment income	1				1
Due to brokers, net (pending trades with brokers)	(1)				(1)
Total pension plan assets	$1,011				$984

	2021				2020
	Fair	Level	Level	Level	Fair	Level	Level	Level
IPL	Value	1	2	3	Value	1	2	3
Cash and equivalents	$16	$—	$16	$—	$21	$—	$21	$—
Equity securities - U.S.	117	117	—	—	84	84	—	—
Equity securities - international	—	—	—	—	69	69	—	—
Global asset securities	24	24	—	—	21	21	—	—
Fixed income securities	87	21	66	—	62	26	36	—
Total assets in fair value hierarchy	244	$162	$82	$—	257	$200	$57	$—
Assets measured at net asset value	218				196
Total pension plan assets	$462				$453

	2021				2020
	Fair	Level	Level	Level	Fair	Level	Level	Level
WPL	Value	1	2	3	Value	1	2	3
Cash and equivalents	$16	$—	$16	$—	$20	$—	$20	$—
Equity securities - U.S.	114	114	—	—	81	81	—	—
Equity securities - international	—	—	—	—	67	67	—	—
Global asset securities	23	23	—	—	20	20	—	—
Fixed income securities	85	21	64	—	59	25	34	—
Total assets in fair value hierarchy	238	$158	$80	$—	247	$193	$54	$—
Assets measured at net asset value	212				189
Total pension plan assets	$450				$436

Pension Plans, Defined Benefit [Member] | IPL [Member]

Defined Benefit Plan Disclosure [Line Items]

Fair Value Of Plan Assets By Asset Category, Fair Value Hierarchy Level and Allocations

At December 31, 2021, the current target ranges and actual allocations for the defined benefit pension plan assets were as follows:

	Target Range			Actual
	Allocation			Allocation
Cash and equivalents	0%	-	5%	3%
Equity securities - U.S.	14%	-	54%	34%
Equity securities - international	11%	-	31%	21%
Global asset securities	5%	-	15%	9%
Fixed income securities	25%	-	45%	33%

At December 31, the fair values of qualified and non-qualified defined benefit pension plan assets were as follows (in millions):

	2021				2020
	Fair	Level	Level	Level	Fair	Level	Level	Level
Alliant Energy	Value	1	2	3	Value	1	2	3
Cash and equivalents	$35	$—	$35	$—	$46	$—	$46	$—
Equity securities - U.S.	256	256	—	—	182	182	—	—
Equity securities - international	—	—	—	—	151	151	—	—
Global asset securities	52	52	—	—	45	45	—	—
Fixed income securities	191	47	144	—	134	56	78	—
Total assets in fair value hierarchy	534	$355	$179	$—	558	$434	$124	$—
Assets measured at net asset value	477				426
Accrued investment income	1				1
Due to brokers, net (pending trades with brokers)	(1)				(1)
Total pension plan assets	$1,011				$984

	2021				2020
	Fair	Level	Level	Level	Fair	Level	Level	Level
IPL	Value	1	2	3	Value	1	2	3
Cash and equivalents	$16	$—	$16	$—	$21	$—	$21	$—
Equity securities - U.S.	117	117	—	—	84	84	—	—
Equity securities - international	—	—	—	—	69	69	—	—
Global asset securities	24	24	—	—	21	21	—	—
Fixed income securities	87	21	66	—	62	26	36	—
Total assets in fair value hierarchy	244	$162	$82	$—	257	$200	$57	$—
Assets measured at net asset value	218				196
Total pension plan assets	$462				$453

	2021				2020
	Fair	Level	Level	Level	Fair	Level	Level	Level
WPL	Value	1	2	3	Value	1	2	3
Cash and equivalents	$16	$—	$16	$—	$20	$—	$20	$—
Equity securities - U.S.	114	114	—	—	81	81	—	—
Equity securities - international	—	—	—	—	67	67	—	—
Global asset securities	23	23	—	—	20	20	—	—
Fixed income securities	85	21	64	—	59	25	34	—
Total assets in fair value hierarchy	238	$158	$80	$—	247	$193	$54	$—
Assets measured at net asset value	212				189
Total pension plan assets	$450				$436

Pension Plans, Defined Benefit [Member] | WPL [Member]

Defined Benefit Plan Disclosure [Line Items]

Fair Value Of Plan Assets By Asset Category, Fair Value Hierarchy Level and Allocations

At December 31, 2021, the current target ranges and actual allocations for the defined benefit pension plan assets were as follows:

	Target Range			Actual
	Allocation			Allocation
Cash and equivalents	0%	-	5%	3%
Equity securities - U.S.	14%	-	54%	34%
Equity securities - international	11%	-	31%	21%
Global asset securities	5%	-	15%	9%
Fixed income securities	25%	-	45%	33%

At December 31, the fair values of qualified and non-qualified defined benefit pension plan assets were as follows (in millions):

	2021				2020
	Fair	Level	Level	Level	Fair	Level	Level	Level
Alliant Energy	Value	1	2	3	Value	1	2	3
Cash and equivalents	$35	$—	$35	$—	$46	$—	$46	$—
Equity securities - U.S.	256	256	—	—	182	182	—	—
Equity securities - international	—	—	—	—	151	151	—	—
Global asset securities	52	52	—	—	45	45	—	—
Fixed income securities	191	47	144	—	134	56	78	—
Total assets in fair value hierarchy	534	$355	$179	$—	558	$434	$124	$—
Assets measured at net asset value	477				426
Accrued investment income	1				1
Due to brokers, net (pending trades with brokers)	(1)				(1)
Total pension plan assets	$1,011				$984

	2021				2020
	Fair	Level	Level	Level	Fair	Level	Level	Level
IPL	Value	1	2	3	Value	1	2	3
Cash and equivalents	$16	$—	$16	$—	$21	$—	$21	$—
Equity securities - U.S.	117	117	—	—	84	84	—	—
Equity securities - international	—	—	—	—	69	69	—	—
Global asset securities	24	24	—	—	21	21	—	—
Fixed income securities	87	21	66	—	62	26	36	—
Total assets in fair value hierarchy	244	$162	$82	$—	257	$200	$57	$—
Assets measured at net asset value	218				196
Total pension plan assets	$462				$453

	2021				2020
	Fair	Level	Level	Level	Fair	Level	Level	Level
WPL	Value	1	2	3	Value	1	2	3
Cash and equivalents	$16	$—	$16	$—	$20	$—	$20	$—
Equity securities - U.S.	114	114	—	—	81	81	—	—
Equity securities - international	—	—	—	—	67	67	—	—
Global asset securities	23	23	—	—	20	20	—	—
Fixed income securities	85	21	64	—	59	25	34	—
Total assets in fair value hierarchy	238	$158	$80	$—	247	$193	$54	$—
Assets measured at net asset value	212				189
Total pension plan assets	$450				$436

Other Postretirement Benefits Plans [Member]

Defined Benefit Plan Disclosure [Line Items]

Fair Value Of Plan Assets By Asset Category, Fair Value Hierarchy Level and Allocations

At December 31, 2021, the current target ranges and actual allocations for VEBA trusts with assets greater than $5 million and the WPL 401(h) assets were as follows:

	Target Range			Actual
	Allocation			Allocation
Cash and equivalents	0%	-	5%	1%
Equity securities - U.S.	0%	-	55%	35%
Fixed income securities	40%	-	100%	64%

At December 31, the fair values of OPEB plan assets were as follows (in millions):

	2021				2020
	Fair	Level	Level	Level	Fair	Level	Level	Level
Alliant Energy	Value	1	2	3	Value	1	2	3
Cash and equivalents	$5	$—	$5	$—	$2	$—	$2	$—
Equity securities - U.S.	11	11	—	—	4	4	—	—
Equity securities - international	—	—	—	—	3	3	—	—
Global asset securities	1	1	—	—	—	—	—	—
Fixed income securities	60	58	2	—	72	71	1	—
Total assets in fair value hierarchy	77	$70	$7	$—	81	$78	$3	$—
Assets measured at net asset value	29				27
Total OPEB plan assets	$106				$108

	2021				2020
	Fair	Level	Level	Level	Fair	Level	Level	Level
IPL	Value	1	2	3	Value	1	2	3
Cash and equivalents	$1	$—	$1	$—	$1	$—	$1	$—
Equity securities - U.S.	8	8	—	—	—	—	—	—
Fixed income securities	42	42	—	—	51	51	—	—
Total assets in fair value hierarchy	51	$50	$1	$—	52	$51	$1	$—
Assets measured at net asset value	23				22
Total OPEB plan assets	$74				$74

	2021				2020
	Fair	Level	Level	Level	Fair	Level	Level	Level
WPL	Value	1	2	3	Value	1	2	3
Cash and equivalents	$1	$—	$1	$—	$—	$—	$—	$—
Equity securities - U.S.	1	1	—	—	—	—	—	—
Fixed income securities	15	15	—	—	18	18	—	—
Total OPEB plan assets	$17	$16	$1	$—	$18	$18	$—	$—

Other Postretirement Benefits Plans [Member] | IPL [Member]

Defined Benefit Plan Disclosure [Line Items]

Fair Value Of Plan Assets By Asset Category, Fair Value Hierarchy Level and Allocations

At December 31, 2021, the current target ranges and actual allocations for VEBA trusts with assets greater than $5 million and the WPL 401(h) assets were as follows:

	Target Range			Actual
	Allocation			Allocation
Cash and equivalents	0%	-	5%	1%
Equity securities - U.S.	0%	-	55%	35%
Fixed income securities	40%	-	100%	64%

At December 31, the fair values of OPEB plan assets were as follows (in millions):

	2021				2020
	Fair	Level	Level	Level	Fair	Level	Level	Level
Alliant Energy	Value	1	2	3	Value	1	2	3
Cash and equivalents	$5	$—	$5	$—	$2	$—	$2	$—
Equity securities - U.S.	11	11	—	—	4	4	—	—
Equity securities - international	—	—	—	—	3	3	—	—
Global asset securities	1	1	—	—	—	—	—	—
Fixed income securities	60	58	2	—	72	71	1	—
Total assets in fair value hierarchy	77	$70	$7	$—	81	$78	$3	$—
Assets measured at net asset value	29				27
Total OPEB plan assets	$106				$108

	2021				2020
	Fair	Level	Level	Level	Fair	Level	Level	Level
IPL	Value	1	2	3	Value	1	2	3
Cash and equivalents	$1	$—	$1	$—	$1	$—	$1	$—
Equity securities - U.S.	8	8	—	—	—	—	—	—
Fixed income securities	42	42	—	—	51	51	—	—
Total assets in fair value hierarchy	51	$50	$1	$—	52	$51	$1	$—
Assets measured at net asset value	23				22
Total OPEB plan assets	$74				$74

	2021				2020
	Fair	Level	Level	Level	Fair	Level	Level	Level
WPL	Value	1	2	3	Value	1	2	3
Cash and equivalents	$1	$—	$1	$—	$—	$—	$—	$—
Equity securities - U.S.	1	1	—	—	—	—	—	—
Fixed income securities	15	15	—	—	18	18	—	—
Total OPEB plan assets	$17	$16	$1	$—	$18	$18	$—	$—

Other Postretirement Benefits Plans [Member] | WPL [Member]

Defined Benefit Plan Disclosure [Line Items]

Fair Value Of Plan Assets By Asset Category, Fair Value Hierarchy Level and Allocations

At December 31, 2021, the current target ranges and actual allocations for VEBA trusts with assets greater than $5 million and the WPL 401(h) assets were as follows:

	Target Range			Actual
	Allocation			Allocation
Cash and equivalents	0%	-	5%	1%
Equity securities - U.S.	0%	-	55%	35%
Fixed income securities	40%	-	100%	64%

At December 31, the fair values of OPEB plan assets were as follows (in millions):

	2021				2020
	Fair	Level	Level	Level	Fair	Level	Level	Level
Alliant Energy	Value	1	2	3	Value	1	2	3
Cash and equivalents	$5	$—	$5	$—	$2	$—	$2	$—
Equity securities - U.S.	11	11	—	—	4	4	—	—
Equity securities - international	—	—	—	—	3	3	—	—
Global asset securities	1	1	—	—	—	—	—	—
Fixed income securities	60	58	2	—	72	71	1	—
Total assets in fair value hierarchy	77	$70	$7	$—	81	$78	$3	$—
Assets measured at net asset value	29				27
Total OPEB plan assets	$106				$108

	2021				2020
	Fair	Level	Level	Level	Fair	Level	Level	Level
IPL	Value	1	2	3	Value	1	2	3
Cash and equivalents	$1	$—	$1	$—	$1	$—	$1	$—
Equity securities - U.S.	8	8	—	—	—	—	—	—
Fixed income securities	42	42	—	—	51	51	—	—
Total assets in fair value hierarchy	51	$50	$1	$—	52	$51	$1	$—
Assets measured at net asset value	23				22
Total OPEB plan assets	$74				$74

	2021				2020
	Fair	Level	Level	Level	Fair	Level	Level	Level
WPL	Value	1	2	3	Value	1	2	3
Cash and equivalents	$1	$—	$1	$—	$—	$—	$—	$—
Equity securities - U.S.	1	1	—	—	—	—	—	—
Fixed income securities	15	15	—	—	18	18	—	—
Total OPEB plan assets	$17	$16	$1	$—	$18	$18	$—	$—

401(k) Savings Plan [Member]

Defined Benefit Plan Disclosure [Line Items]

Employees Participate In Defined Contribution Retirement Plans

Costs related to the 401(k) savings plans, which are partially based on the participants’ contributions and include allocated costs associated with Corporate Services employees for IPL and WPL, were as follows (in millions):

	Alliant Energy			IPL			WPL
	2021	2020	2019	2021	2020	2019	2021	2020	2019
401(k) costs	$26	$25	$25	$13	$13	$13	$12	$12	$12

401(k) Savings Plan [Member] | IPL [Member]

Defined Benefit Plan Disclosure [Line Items]

Employees Participate In Defined Contribution Retirement Plans

Costs related to the 401(k) savings plans, which are partially based on the participants’ contributions and include allocated costs associated with Corporate Services employees for IPL and WPL, were as follows (in millions):

	Alliant Energy			IPL			WPL
	2021	2020	2019	2021	2020	2019	2021	2020	2019
401(k) costs	$26	$25	$25	$13	$13	$13	$12	$12	$12

401(k) Savings Plan [Member] | WPL [Member]

Defined Benefit Plan Disclosure [Line Items]

Employees Participate In Defined Contribution Retirement Plans

Costs related to the 401(k) savings plans, which are partially based on the participants’ contributions and include allocated costs associated with Corporate Services employees for IPL and WPL, were as follows (in millions):

	Alliant Energy			IPL			WPL
	2021	2020	2019	2021	2020	2019	2021	2020	2019
401(k) costs	$26	$25	$25	$13	$13	$13	$12	$12	$12

Performance Shares Equity Awards [Member]

Defined Benefit Plan Disclosure [Line Items]

Schedule Of Equity-based Compensation Plans Activity

A summary of the 2021, 2020 and 2019 performance shares activity, with amounts representing the target number of awards, was as follows:

	2021		2020		2019
	Performance Shares - Equity	Weighted Average Grant Date Fair Value	Performance Shares - Equity	Weighted Average Grant Date Fair Value	Performance Shares - Equity	Weighted Average Grant Date Fair Value
Nonvested awards, January 1	129,156	$54.63	74,193	$47.44	—	$—
Granted	73,112	46.19	56,204	64.04	91,816	47.23
Forfeited	(5,839)	51.07	(1,241)	50.94	(17,623)	46.35
Nonvested awards, December 31	196,429	51.59	129,156	54.63	74,193	47.44

Performance Shares and Performance Units Liability Awards [Member]

Defined Benefit Plan Disclosure [Line Items]

Schedule Of Equity-based Compensation Plans Activity

A summary of these performance shares and performance units activity, with amounts representing the target number of awards, was as follows:

	Performance Shares (granted prior to 2019)			Performance Units (granted prior to 2019)
	2021	2020	2019	2021	2020	2019
Nonvested awards, January 1	68,307	131,872	203,188	16,801	34,574	57,761
Vested	(68,307)	(63,565)	(66,322)	(16,801)	(16,661)	(20,131)
Forfeited	—	—	(4,994)	—	(1,112)	(3,056)
Nonvested awards, December 31	—	68,307	131,872	—	16,801	34,574

Certain performance shares and performance units vested, resulting in payouts (a combination of cash and common stock for the performance shares and cash only for the performance units) as follows:

	Performance Shares (granted prior to 2019)			Performance Units (granted prior to 2019)
	2021	2020	2019	2021	2020	2019
	2018 Grant	2017 Grant	2016 Grant	2018 Grant	2017 Grant	2016 Grant
Performance awards vested	68,307	63,565	66,322	16,801	16,661	20,131
Percentage of target number of performance awards	172.5%	155.0%	142.5%	172.5%	155.0%	142.5%
Aggregate payout value (in millions)	$7	$6	$4	$2	$2	$1
Payout - cash (in millions)	$5	$5	$4	$2	$2	$1
Payout - common stock shares issued	13,644	9,543	6,447	N/A	N/A	N/A

Restricted Stock Units Equity Awards [Member]

Defined Benefit Plan Disclosure [Line Items]

Schedule Of Equity-based Compensation Plans Activity

A summary of the 2021, 2020 and 2019 restricted stock units activity was as follows:

	2021		2020		2019
	Restricted Stock Units - Equity	Weighted Average Grant Date Fair Value	Restricted Stock Units - Equity	Weighted Average Grant Date Fair Value	Restricted Stock Units - Equity	Weighted Average Grant Date Fair Value
Nonvested units, January 1	146,549	$51.54	89,281	$46.04	—	$—
Granted	80,152	48.65	61,056	59.42	105,348	45.98
Forfeited	(8,882)	49.84	(3,788)	49.01	(16,067)	45.63
Nonvested units, December 31	217,819	50.54	146,549	51.54	89,281	46.04

Restricted Stock Unit Liability Awards [Member]

Defined Benefit Plan Disclosure [Line Items]

Schedule Of Equity-based Compensation Plans Activity

A summary of the restricted stock units granted prior to 2019 activity was as follows:

	2021	2020	2019
Nonvested units, January 1	58,550	113,033	174,163
Vested	(58,550)	(54,483)	(56,849)
Forfeited	—	—	(4,281)
Nonvested units, December 31	—	58,550	113,033

Performance Restricted Stock Units Equity Awards [Member]

Defined Benefit Plan Disclosure [Line Items]

Schedule Of Equity-based Compensation Plans Activity

A summary of the performance restricted stock units activity, with amounts representing the target number of units, was as follows:

	2021		2020		2019
	Units	Weighted Average Grant Date Fair Value	Units	Weighted Average Grant Date Fair Value	Units	Weighted Average Grant Date Fair Value
Nonvested units, January 1	197,463	$47.31	206,065	$41.50	203,188	$37.23
Granted	73,112	48.66	56,204	59.37	91,816	46.10
Vested	(68,307)	38.60	(63,565)	39.12	(66,322)	33.93
Forfeited	(5,839)	50.46	(1,241)	49.25	(22,617)	44.00
Nonvested units, December 31	196,429	50.74	197,463	47.31	206,065	41.50