Alliant Energy (LNT) 10-Q 8 Nov 22 2022 Q3 Quarterly report Financial data

Document And Entity Information

Document And Entity Information	9 Months Ended
	Sep. 30, 2022 shares
Entity Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2022
Document Transition Report	false
Entity Registrant Name	ALLIANT ENERGY CORP
Entity Central Index Key	0000352541
Entity Incorporation, State or Country Code	WI
Entity Address, Address Line One	4902 N. Biltmore Lane
Entity Address, City or Town	Madison
Entity Address, State or Province	WI
Entity Address, Postal Zip Code	53718
City Area Code	608
Local Phone Number	458-3311
Entity File Number	1-9894
Entity Tax Identification Number	39-1380265
Title of 12(b) Security	Common Stock, $0.01 Par Value
Trading Symbol	LNT
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding	251,021,830
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	Q3
Amendment Flag	false
IPL [Member]
Entity Information [Line Items]
Entity Registrant Name	INTERSTATE POWER & LIGHT CO
Entity Central Index Key	0000052485
Entity Incorporation, State or Country Code	IA
Entity Address, Address Line One	Alliant Energy Tower
Entity Address, City or Town	Cedar Rapids
Entity Address, State or Province	IA
Entity Address, Postal Zip Code	52401
City Area Code	319
Local Phone Number	786-4411
Entity File Number	1-4117
Entity Tax Identification Number	42-0331370
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding	13,370,788
WPL [Member]
Entity Information [Line Items]
Entity Registrant Name	WISCONSIN POWER & LIGHT CO
Entity Central Index Key	0000107832
Entity Incorporation, State or Country Code	WI
Entity Address, Address Line One	4902 N. Biltmore Lane
Entity Address, City or Town	Madison
Entity Address, State or Province	WI
Entity Address, Postal Zip Code	53718
City Area Code	608
Local Phone Number	458-3311
Entity File Number	0-337
Entity Tax Identification Number	39-0714890
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding	13,236,601

Condensed Consolidated Statemen

Condensed Consolidated Statements Of Income - USD ($) shares in Thousands, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Revenues:
Electric utility	$ 1,039	$ 939	$ 2,624	$ 2,357
Gas utility	62	50	418	289
Other utility	11	13	35	36
Non-utility	23	22	70	60
Total revenues	1,135	1,024	3,147	2,742
Operating expenses:
Electric production fuel and purchased power	274	207	633	478
Electric transmission service	157	148	428	403
Cost of gas sold	26	18	242	149
Other operation and maintenance	172	171	492	477
Depreciation and amortization	169	165	501	494
Taxes other than income taxes	28	26	82	78
Total operating expenses	826	735	2,378	2,079
Operating income	309	289	769	663
Other (income) and deductions:
Interest expense	83	68	235	206
Equity income from unconsolidated investments, net	(5)	(13)	(37)	(47)
Allowance for funds used during construction	(10)	(7)	(34)	(16)
Other	0	3	0	7
Total other (income) and deductions	68	51	164	150
Income before income taxes	241	238	605	513
Income tax expense (benefit)	14	(21)	26	(66)
Net income	227	259	579	579
Preferred dividend requirements of Interstate Power and Light Company	0	3	0	8
Net income attributable to common shareowners	$ 227	$ 256	$ 579	$ 571
Weighted average number of common shares outstanding:
Basic (in shares)	251,000	250,300	250,800	250,200
Diluted (in shares)	251,300	250,800	251,100	250,600
Earnings per weighted average common share attributable to Alliant Energy common shareowners:
Basic (in dollars per share)	$ 0.90	$ 1.02	$ 2.31	$ 2.28
Diluted (in dollars per share)	$ 0.90	$ 1.02	$ 2.31	$ 2.28
IPL [Member]
Revenues:
Electric utility	$ 596	$ 555	$ 1,438	$ 1,343
Gas utility	33	31	224	165
Other utility	11	13	34	35
Total revenues	640	599	1,696	1,543
Operating expenses:
Electric production fuel and purchased power	140	101	290	215
Electric transmission service	115	103	303	274
Cost of gas sold	14	12	126	84
Other operation and maintenance	90	95	260	253
Depreciation and amortization	95	94	285	281
Taxes other than income taxes	15	14	43	42
Total operating expenses	469	419	1,307	1,149
Operating income	171	180	389	394
Other (income) and deductions:
Interest expense	37	34	111	103
Allowance for funds used during construction	(3)	(2)	(8)	(7)
Other	(1)	0	(2)	2
Total other (income) and deductions	33	32	101	98
Income before income taxes	138	148	288	296
Income tax expense (benefit)	(16)	(12)	(39)	(34)
Net income	154	160	327	330
Preferred dividend requirements of Interstate Power and Light Company	0	3	0	8
Net income attributable to common shareowners	154	157	327	322
WPL [Member]
Revenues:
Electric utility	443	384	1,186	1,014
Gas utility	29	19	194	124
Other utility	0	0	1	1
Total revenues	472	403	1,381	1,139
Operating expenses:
Electric production fuel and purchased power	134	105	343	263
Electric transmission service	42	44	125	128
Cost of gas sold	13	6	117	65
Other operation and maintenance	70	66	193	194
Depreciation and amortization	71	70	211	209
Taxes other than income taxes	11	12	35	35
Total operating expenses	341	303	1,024	894
Operating income	131	100	357	245
Other (income) and deductions:
Interest expense	31	25	86	77
Allowance for funds used during construction	(7)	(5)	(26)	(9)
Other	0	2	0	3
Total other (income) and deductions	24	22	60	71
Income before income taxes	107	78	297	174
Income tax expense (benefit)	16	(15)	50	(41)
Net income	$ 91	$ 93	$ 247	$ 215

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Millions	Sep. 30, 2022	Dec. 31, 2021
Current assets:
Cash and cash equivalents	$ 344	$ 39
Accounts receivable, less allowance for expected credit losses	509	440
Production fuel, at weighted average cost	49	51
Gas stored underground, at weighted average cost	124	82
Materials and supplies, at weighted average cost	126	113
Regulatory assets	177	104
Other	364	240
Total current assets	1,693	1,069
Property, plant and equipment, net	15,858	14,987
Investments:
ATC Holdings	351	338
Other	200	179
Total investments	551	517
Other assets:
Regulatory assets	1,864	1,836
Deferred charges and other	239	144
Total other assets	2,103	1,980
Total assets	20,205	18,553
Current liabilities:
Current maturities of long-term debt	658	633
Commercial paper	383	515
Accounts payable	786	436
Accrued taxes	86	58
Regulatory liabilities	229	186
Other	280	226
Total current liabilities	2,422	2,054
Long-term debt, net (excluding current portion)	7,570	6,735
Other liabilities:
Deferred tax liabilities	1,919	1,927
Regulatory liabilities	1,158	1,085
Pension and other benefit obligations	349	374
Other	522	388
Total other liabilities	3,948	3,774
Commitments and contingencies (Note 13)
Common equity:
Common stock	3	3
Additional paid-in capital	2,767	2,749
Retained earnings	3,508	3,250
Shares in deferred compensation trust - 395,224 and 383,532 shares at a weighted average cost of $32.23 and $30.59 per share	(13)	(12)
Total common equity	6,265	5,990
Total liabilities and equity	20,205	18,553
IPL [Member]
Current assets:
Cash and cash equivalents	45	34
Accounts receivable, less allowance for expected credit losses	286	241
Income tax refunds receivable	1	8
Production fuel, at weighted average cost	31	29
Gas stored underground, at weighted average cost	66	40
Materials and supplies, at weighted average cost	77	70
Regulatory assets	108	73
Other	134	69
Total current assets	748	564
Property, plant and equipment, net	8,013	7,983
Other assets:
Regulatory assets	1,315	1,370
Deferred charges and other	132	79
Total other assets	1,447	1,449
Total assets	10,208	9,996
Current liabilities:
Accounts payable	232	173
Accounts payable to associated companies	37	39
Accrued taxes	69	56
Accrued interest	35	36
Regulatory liabilities	105	84
Other	112	67
Total current liabilities	590	455
Long-term debt, net (excluding current portion)	3,645	3,643
Other liabilities:
Deferred tax liabilities	1,029	1,083
Regulatory liabilities	656	607
Pension and other benefit obligations	118	127
Other	314	312
Total other liabilities	2,117	2,129
Commitments and contingencies (Note 13)
Common equity:
Common stock	33	33
Additional paid-in capital	2,807	2,807
Retained earnings	1,016	929
Total common equity	3,856	3,769
Total liabilities and equity	10,208	9,996
WPL [Member]
Current assets:
Cash and cash equivalents	299	2
Accounts receivable, less allowance for expected credit losses	211	188
Production fuel, at weighted average cost	18	23
Gas stored underground, at weighted average cost	58	42
Materials and supplies, at weighted average cost	47	41
Regulatory assets	69	31
Prepaid gross receipts tax	31	40
Other	130	86
Total current assets	863	453
Property, plant and equipment, net	7,371	6,538
Other assets:
Regulatory assets	549	466
Deferred charges and other	115	61
Total other assets	664	527
Total assets	8,898	7,518
Current liabilities:
Current maturities of long-term debt	250	250
Commercial paper	0	236
Accounts payable	470	190
Accounts payable to associated companies	51	39
Regulatory liabilities	124	102
Other	93	73
Total current liabilities	988	890
Long-term debt, net (excluding current portion)	2,769	2,179
Other liabilities:
Deferred tax liabilities	783	753
Regulatory liabilities	502	478
Pension and other benefit obligations	148	159
Other	352	236
Total other liabilities	1,785	1,626
Commitments and contingencies (Note 13)
Common equity:
Common stock	66	66
Additional paid-in capital	2,123	1,704
Retained earnings	1,167	1,053
Total common equity	3,356	2,823
Total liabilities and equity	$ 8,898	$ 7,518

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Sep. 30, 2022	Dec. 31, 2021
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	480,000,000	480,000,000
Common stock, shares outstanding (in shares)	251,021,830	250,474,529
Shares in deferred compensation trust (in shares)	395,224	383,532
Shares in deferred compensation trust, weighted average cost per share (in dollars per share)	$ 32.23	$ 30.59
IPL [Member]
Common stock, par value (in dollars per share)	$ 2.50	$ 2.50
Common stock, shares authorized (in shares)	24,000,000	24,000,000
Common stock, shares outstanding (in shares)	13,370,788	13,370,788
WPL [Member]
Common stock, par value (in dollars per share)	$ 5	$ 5
Common stock, shares authorized (in shares)	18,000,000	18,000,000
Common stock, shares outstanding (in shares)	13,236,601	13,236,601

Condensed Consolidated Statem_2

Condensed Consolidated Statements Of Cash Flows - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021
Cash flows from operating activities:
Net income	$ 579	$ 579
Adjustments to reconcile net income to net cash flows from operating activities:
Depreciation and amortization	501	494
Deferred tax expense (benefit) and tax credits	8	(69)
Other	(8)	7
Other changes in assets and liabilities:
Accounts receivable	(425)	(397)
Derivative assets	(184)	(202)
Regulatory assets	(102)	(21)
Accounts payable	90	0
Derivative liabilities	89	(21)
Regulatory liabilities	89	25
Deferred income taxes	(15)	160
Pension and other benefit obligations	(25)	(59)
Other	(112)	(19)
Net cash flows from operating activities	485	477
Cash flows from (used for) investing activities:
Utility business construction and acquisition expenditures	(873)	(772)
Other construction and acquisition expenditures	(69)	(60)
Cash receipts on sold receivables	358	423
Other	(15)	(43)
Net cash flows from (used for) investing activities	(599)	(452)
Cash flows from (used for) financing activities:
Common stock dividends	(322)	(304)
Proceeds from issuance of long-term debt	1,238	300
Payments to retire long-term debt	(379)	(4)
Net change in commercial paper	(132)	(73)
Contributions from noncontrolling interest	29	0
Distributions to noncontrolling interest	(29)	0
Other	16	24
Net cash flows from (used for) financing activities	421	(57)
Net increase (decrease) in cash, cash equivalents and restricted cash	307	(32)
Cash, cash equivalents and restricted cash at beginning of period	40	56
Cash, cash equivalents and restricted cash at end of period	347	24
Supplemental cash flows information:
Interest	(220)	(197)
Income taxes, net	(7)	(1)
Significant non-cash investing and financing activities:
Accrued capital expenditures	403	91
Beneficial interest obtained in exchange for securitized accounts receivable	248	164
IPL [Member]
Cash flows from operating activities:
Net income	327	330
Adjustments to reconcile net income to net cash flows from operating activities:
Depreciation and amortization	285	281
Deferred tax expense (benefit) and tax credits	(24)	(13)
Other	(8)	(1)
Other changes in assets and liabilities:
Accounts receivable	(397)	(412)
Derivative assets	(118)	(86)
Regulatory assets	18	(33)
Accounts payable	71	5
Derivative liabilities	62	(9)
Regulatory liabilities	61	30
Deferred income taxes	(30)	56
Pension and other benefit obligations	(9)	(25)
Other	(72)	(28)
Net cash flows from operating activities	166	95
Cash flows from (used for) investing activities:
Utility business construction and acquisition expenditures	(269)	(285)
Cash receipts on sold receivables	358	423
Other	(5)	(16)
Net cash flows from (used for) investing activities	84	122
Cash flows from (used for) financing activities:
Common stock dividends	(240)	(301)
Capital contributions from parent	0	50
Other	1	(3)
Net cash flows from (used for) financing activities	(239)	(254)
Net increase (decrease) in cash, cash equivalents and restricted cash	11	(37)
Cash, cash equivalents and restricted cash at beginning of period	34	50
Cash, cash equivalents and restricted cash at end of period	45	13
Supplemental cash flows information:
Interest	(111)	(106)
Income taxes, net	33	28
Significant non-cash investing and financing activities:
Accrued capital expenditures	43	30
Beneficial interest obtained in exchange for securitized accounts receivable	248	164
WPL [Member]
Cash flows from operating activities:
Net income	247	215
Adjustments to reconcile net income to net cash flows from operating activities:
Depreciation and amortization	211	209
Deferred tax expense (benefit) and tax credits	11	(63)
Other	(7)	12
Other changes in assets and liabilities:
Derivative assets	(66)	(116)
Regulatory assets	(120)	11
Deferred income taxes	20	108
Other	(17)	(27)
Net cash flows from operating activities	279	349
Cash flows from (used for) investing activities:
Utility business construction and acquisition expenditures	(604)	(487)
Other	(8)	(23)
Net cash flows from (used for) investing activities	(612)	(510)
Cash flows from (used for) financing activities:
Common stock dividends	(133)	(126)
Capital contributions from parent	420	245
Proceeds from issuance of long-term debt	588	300
Net change in commercial paper	(236)	(254)
Contributions from noncontrolling interest	29	0
Distributions to noncontrolling interest	(29)	0
Other	(9)	(3)
Net cash flows from (used for) financing activities	630	162
Net increase (decrease) in cash, cash equivalents and restricted cash	297	1
Cash, cash equivalents and restricted cash at beginning of period	2	3
Cash, cash equivalents and restricted cash at end of period	299	4
Supplemental cash flows information:
Interest	(78)	(72)
Income taxes, net	(51)	(24)
Significant non-cash investing and financing activities:
Accrued capital expenditures	$ 355	$ 59

Summary Of Significant Accounti

Summary Of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2022
Summary Of Significant Accounting Policies	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES NOTE 1(a) General - The interim unaudited Financial Statements included herein have been prepared pursuant to the rules and regulations of the SEC. Accordingly, certain information and note disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted, although management believes that the disclosures are adequate to make the information presented not misleading. These Financial Statements should be read in conjunction with the financial statements and the notes thereto included in the 2021 Form 10-K . In the opinion of management, all adjustments, which unless otherwise noted are normal and recurring in nature, necessary for a fair presentation of the results of operations, financial position and cash flows have been made. Results for the nine months ended September 30, 2022 are not necessarily indicative of results that may be expected for the year ending December 31, 2022. A change in management’s estimates or assumptions could have a material impact on financial condition and results of operations during the period in which such change occurred. Certain prior period amounts in the Financial Statements and Notes have been reclassified to conform to the current period presentation for comparative purposes. NOTE 1(b) Cash and Cash Equivalents - At September 30, 2022, Alliant Energy’s, IPL’s and WPL’s cash and cash equivalents included $334 million, $39 million and $295 million of money market fund investments, respectively, with weighted average interest rates of 3%. NOTE 1(c) Variable Interest Entities (VIEs) - In 2022, WPL 2022 Solar Holdco, LLC was formed as a joint venture to own and operate project companies responsible for the construction, ownership and operation of various solar generation assets. Members of the joint venture were a WPL subsidiary (the managing member) and a tax equity partner. In the second quarter of 2022, the WPL subsidiary and the tax equity partner contributed $62 million and $29 million, respectively, to WPL 2022 Solar Holdco, LLC in exchange for membership interests, and $88 million of the contributed funds were paid to WPL in exchange for equity interests in the project companies. In the second quarter of 2022, Alliant Energy and WPL consolidated this joint venture as it was a VIE in which WPL held a variable interest, and WPL controlled decisions that were significant to the joint venture’s ongoing operations and economic results (i.e., WPL was the primary beneficiary). In August 2022, the Inflation Reduction Act of 2022 was enacted. Following its enactment, WPL evaluated the provisions of the new legislation and determined that retaining full ownership of the solar projects is expected to result in lower costs for its customers. As a result, in the third quarter of 2022, WPL and the tax equity partner terminated the tax equity partnership, and WPL returned the $29 million of initial funding to the tax equity partner. Alliant Energy and WPL no longer expect their solar generation project construction costs to be financed with capital from tax equity partners, which would result in higher rate base amounts compared to those previously approved by the PSCW for WPL’s planned approximately 1,100 MW of solar generation. Alliant Energy and WPL concluded that no disallowance of anticipated higher rate base amounts was required as of September 30, 2022 given full ownership of WPL's planned solar generation is expected to result in lower costs for WPL's customers. Refer to Note 6 for discussion of a noncontrolling interest that was initially associated with the joint venture prior to the termination of the tax equity partnership.
IPL [Member]
Summary Of Significant Accounting Policies	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES NOTE 1(a) General - The interim unaudited Financial Statements included herein have been prepared pursuant to the rules and regulations of the SEC. Accordingly, certain information and note disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted, although management believes that the disclosures are adequate to make the information presented not misleading. These Financial Statements should be read in conjunction with the financial statements and the notes thereto included in the 2021 Form 10-K . In the opinion of management, all adjustments, which unless otherwise noted are normal and recurring in nature, necessary for a fair presentation of the results of operations, financial position and cash flows have been made. Results for the nine months ended September 30, 2022 are not necessarily indicative of results that may be expected for the year ending December 31, 2022. A change in management’s estimates or assumptions could have a material impact on financial condition and results of operations during the period in which such change occurred. Certain prior period amounts in the Financial Statements and Notes have been reclassified to conform to the current period presentation for comparative purposes. NOTE 1(b) Cash and Cash Equivalents - At September 30, 2022, Alliant Energy’s, IPL’s and WPL’s cash and cash equivalents included $334 million, $39 million and $295 million of money market fund investments, respectively, with weighted average interest rates of 3%.
WPL [Member]
Summary Of Significant Accounting Policies	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES NOTE 1(a) General - The interim unaudited Financial Statements included herein have been prepared pursuant to the rules and regulations of the SEC. Accordingly, certain information and note disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted, although management believes that the disclosures are adequate to make the information presented not misleading. These Financial Statements should be read in conjunction with the financial statements and the notes thereto included in the 2021 Form 10-K . In the opinion of management, all adjustments, which unless otherwise noted are normal and recurring in nature, necessary for a fair presentation of the results of operations, financial position and cash flows have been made. Results for the nine months ended September 30, 2022 are not necessarily indicative of results that may be expected for the year ending December 31, 2022. A change in management’s estimates or assumptions could have a material impact on financial condition and results of operations during the period in which such change occurred. Certain prior period amounts in the Financial Statements and Notes have been reclassified to conform to the current period presentation for comparative purposes. NOTE 1(b) Cash and Cash Equivalents - At September 30, 2022, Alliant Energy’s, IPL’s and WPL’s cash and cash equivalents included $334 million, $39 million and $295 million of money market fund investments, respectively, with weighted average interest rates of 3%. NOTE 1(c) Variable Interest Entities (VIEs) - In 2022, WPL 2022 Solar Holdco, LLC was formed as a joint venture to own and operate project companies responsible for the construction, ownership and operation of various solar generation assets. Members of the joint venture were a WPL subsidiary (the managing member) and a tax equity partner. In the second quarter of 2022, the WPL subsidiary and the tax equity partner contributed $62 million and $29 million, respectively, to WPL 2022 Solar Holdco, LLC in exchange for membership interests, and $88 million of the contributed funds were paid to WPL in exchange for equity interests in the project companies. In the second quarter of 2022, Alliant Energy and WPL consolidated this joint venture as it was a VIE in which WPL held a variable interest, and WPL controlled decisions that were significant to the joint venture’s ongoing operations and economic results (i.e., WPL was the primary beneficiary). In August 2022, the Inflation Reduction Act of 2022 was enacted. Following its enactment, WPL evaluated the provisions of the new legislation and determined that retaining full ownership of the solar projects is expected to result in lower costs for its customers. As a result, in the third quarter of 2022, WPL and the tax equity partner terminated the tax equity partnership, and WPL returned the $29 million of initial funding to the tax equity partner. Alliant Energy and WPL no longer expect their solar generation project construction costs to be financed with capital from tax equity partners, which would result in higher rate base amounts compared to those previously approved by the PSCW for WPL’s planned approximately 1,100 MW of solar generation. Alliant Energy and WPL concluded that no disallowance of anticipated higher rate base amounts was required as of September 30, 2022 given full ownership of WPL's planned solar generation is expected to result in lower costs for WPL's customers. Refer to Note 6 for discussion of a noncontrolling interest that was initially associated with the joint venture prior to the termination of the tax equity partnership.

Regulatory Matters

Regulatory Matters	9 Months Ended
	Sep. 30, 2022
Public Utilities, General Disclosures [Line Items]
Regulatory Matters	REGULATORY MATTERS Regulatory Assets and Regulatory Liabilities - Regulatory assets were comprised of the following items (in millions): Alliant Energy IPL WPL September 30, December 31, September 30, December 31, September 30, December 31, Tax-related $913 $934 $842 $884 $71 $50 Pension and OPEB costs 436 462 216 228 220 234 Asset retirement obligations 145 128 104 89 41 39 Commodity cost recovery 129 42 2 2 127 40 Derivatives 102 8 67 4 35 4 Assets retired early 75 92 56 66 19 26 IPL’s DAEC PPA amendment 72 90 72 90 — — WPL’s Western Wisconsin gas distribution expansion investments 49 52 — — 49 52 Other 120 132 64 80 56 52 $2,041 $1,940 $1,423 $1,443 $618 $497 Tax-related - Refer to N ote 9 for discussion of Iowa Tax Reform, which resulted in a decrease in Alliant Energy’s and IPL’s tax-related regulatory assets in the third quarter of 2022. Commodity cost recovery - The cost recovery mechanism for WPL’s retail electric customers is based on forecasts of certain fuel-related costs expected to be incurred during forward-looking test periods and fuel monitoring ranges determined by the PSCW during each retail electric rate proceeding or in a separate fuel cost plan approval proceeding. During the nine months ended September 30, 2022, WPL’s actual fuel-related costs fell outside these fuel monitoring ranges, resulting in a $83 million deferral of higher than expected fuel-related costs as of September 30, 2022. Derivatives - Refer to Note 11 for discussion of changes in Alliant Energy’s, IPL’s and WPL’s derivative liabilities/assets during the nine months ended September 30, 2022, which result in comparable changes to regulatory assets/liabilities on the balance sheets. Regulatory liabilities were comprised of the following items (in millions): Alliant Energy IPL WPL September 30, December 31, September 30, December 31, September 30, December 31, Tax-related $582 $585 $304 $312 $278 $273 Cost of removal obligations 398 384 258 252 140 132 Derivatives 312 166 164 77 148 89 WPL’s West Riverside liquidated damages 33 36 — — 33 36 Electric transmission cost recovery 16 51 4 27 12 24 Other 46 49 31 23 15 26 $1,387 $1,271 $761 $691 $626 $580
IPL [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Matters	REGULATORY MATTERS Regulatory Assets and Regulatory Liabilities - Regulatory assets were comprised of the following items (in millions): Alliant Energy IPL WPL September 30, December 31, September 30, December 31, September 30, December 31, Tax-related $913 $934 $842 $884 $71 $50 Pension and OPEB costs 436 462 216 228 220 234 Asset retirement obligations 145 128 104 89 41 39 Commodity cost recovery 129 42 2 2 127 40 Derivatives 102 8 67 4 35 4 Assets retired early 75 92 56 66 19 26 IPL’s DAEC PPA amendment 72 90 72 90 — — WPL’s Western Wisconsin gas distribution expansion investments 49 52 — — 49 52 Other 120 132 64 80 56 52 $2,041 $1,940 $1,423 $1,443 $618 $497 Tax-related - Refer to N ote 9 for discussion of Iowa Tax Reform, which resulted in a decrease in Alliant Energy’s and IPL’s tax-related regulatory assets in the third quarter of 2022. Commodity cost recovery - The cost recovery mechanism for WPL’s retail electric customers is based on forecasts of certain fuel-related costs expected to be incurred during forward-looking test periods and fuel monitoring ranges determined by the PSCW during each retail electric rate proceeding or in a separate fuel cost plan approval proceeding. During the nine months ended September 30, 2022, WPL’s actual fuel-related costs fell outside these fuel monitoring ranges, resulting in a $83 million deferral of higher than expected fuel-related costs as of September 30, 2022. Derivatives - Refer to Note 11 for discussion of changes in Alliant Energy’s, IPL’s and WPL’s derivative liabilities/assets during the nine months ended September 30, 2022, which result in comparable changes to regulatory assets/liabilities on the balance sheets. Regulatory liabilities were comprised of the following items (in millions): Alliant Energy IPL WPL September 30, December 31, September 30, December 31, September 30, December 31, Tax-related $582 $585 $304 $312 $278 $273 Cost of removal obligations 398 384 258 252 140 132 Derivatives 312 166 164 77 148 89 WPL’s West Riverside liquidated damages 33 36 — — 33 36 Electric transmission cost recovery 16 51 4 27 12 24 Other 46 49 31 23 15 26 $1,387 $1,271 $761 $691 $626 $580
WPL [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Matters	REGULATORY MATTERS Regulatory Assets and Regulatory Liabilities - Regulatory assets were comprised of the following items (in millions): Alliant Energy IPL WPL September 30, December 31, September 30, December 31, September 30, December 31, Tax-related $913 $934 $842 $884 $71 $50 Pension and OPEB costs 436 462 216 228 220 234 Asset retirement obligations 145 128 104 89 41 39 Commodity cost recovery 129 42 2 2 127 40 Derivatives 102 8 67 4 35 4 Assets retired early 75 92 56 66 19 26 IPL’s DAEC PPA amendment 72 90 72 90 — — WPL’s Western Wisconsin gas distribution expansion investments 49 52 — — 49 52 Other 120 132 64 80 56 52 $2,041 $1,940 $1,423 $1,443 $618 $497 Tax-related - Refer to N ote 9 for discussion of Iowa Tax Reform, which resulted in a decrease in Alliant Energy’s and IPL’s tax-related regulatory assets in the third quarter of 2022. Commodity cost recovery - The cost recovery mechanism for WPL’s retail electric customers is based on forecasts of certain fuel-related costs expected to be incurred during forward-looking test periods and fuel monitoring ranges determined by the PSCW during each retail electric rate proceeding or in a separate fuel cost plan approval proceeding. During the nine months ended September 30, 2022, WPL’s actual fuel-related costs fell outside these fuel monitoring ranges, resulting in a $83 million deferral of higher than expected fuel-related costs as of September 30, 2022. Derivatives - Refer to Note 11 for discussion of changes in Alliant Energy’s, IPL’s and WPL’s derivative liabilities/assets during the nine months ended September 30, 2022, which result in comparable changes to regulatory assets/liabilities on the balance sheets. Regulatory liabilities were comprised of the following items (in millions): Alliant Energy IPL WPL September 30, December 31, September 30, December 31, September 30, December 31, Tax-related $582 $585 $304 $312 $278 $273 Cost of removal obligations 398 384 258 252 140 132 Derivatives 312 166 164 77 148 89 WPL’s West Riverside liquidated damages 33 36 — — 33 36 Electric transmission cost recovery 16 51 4 27 12 24 Other 46 49 31 23 15 26 $1,387 $1,271 $761 $691 $626 $580

Property, Plant and Equipment

Property, Plant and Equipment	9 Months Ended
	Sep. 30, 2022
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment	PROPERTY, PLANT AND EQUIPMENTIn June 2022, WPL announced revised expected timing for the retirements of its remaining coal-fired EGUs in order to help manage regional capacity and changing generation requirements across the MISO region. WPL currently expects to retire the Edgewater Generating Station (414 MW) by June 1, 2025, and Columbia Units 1 and 2 by June 1, 2026 (595 MW in aggregate). In addition, IPL currently expects to retire the coal-fired Lansing Generating Station (275 MW) in the first half of 2023. Alliant Energy, IPL and WPL are working with MISO, state regulatory commissions and other regulatory agencies, as required, to determine the timing of these actions, which are subject to change depending on operational, regulatory, market and other factors.
IPL [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment	PROPERTY, PLANT AND EQUIPMENTIn June 2022, WPL announced revised expected timing for the retirements of its remaining coal-fired EGUs in order to help manage regional capacity and changing generation requirements across the MISO region. WPL currently expects to retire the Edgewater Generating Station (414 MW) by June 1, 2025, and Columbia Units 1 and 2 by June 1, 2026 (595 MW in aggregate). In addition, IPL currently expects to retire the coal-fired Lansing Generating Station (275 MW) in the first half of 2023. Alliant Energy, IPL and WPL are working with MISO, state regulatory commissions and other regulatory agencies, as required, to determine the timing of these actions, which are subject to change depending on operational, regulatory, market and other factors.
WPL [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment	PROPERTY, PLANT AND EQUIPMENTIn June 2022, WPL announced revised expected timing for the retirements of its remaining coal-fired EGUs in order to help manage regional capacity and changing generation requirements across the MISO region. WPL currently expects to retire the Edgewater Generating Station (414 MW) by June 1, 2025, and Columbia Units 1 and 2 by June 1, 2026 (595 MW in aggregate). In addition, IPL currently expects to retire the coal-fired Lansing Generating Station (275 MW) in the first half of 2023. Alliant Energy, IPL and WPL are working with MISO, state regulatory commissions and other regulatory agencies, as required, to determine the timing of these actions, which are subject to change depending on operational, regulatory, market and other factors.

Receivables

Receivables	9 Months Ended
	Sep. 30, 2022
Receivables [Line Items]
Receivables	RECEIVABLES Sales of Accounts Receivable - IPL maintains a Receivables Purchase and Sale Agreement (Receivables Agreement) whereby it may sell its customer accounts receivables, unbilled revenues and certain other accounts receivables to a third party through wholly-owned and consolidated special purpose entities. The transfers of receivables meet the criteria for sale accounting established by the transfer of financial assets accounting rules. As of September 30, 2022, IPL had $109 million of available capacity under its sales of accounts receivable program. IPL’s maximum and average outstanding cash proceeds (based on daily outstanding balances) related to the sales of accounts receivable program for the three and nine months ended September 30 were as follows (in millions): Three Months Nine Months 2022 2021 2022 2021 Maximum outstanding aggregate cash proceeds $36 $110 $66 $110 Average outstanding aggregate cash proceeds 3 65 8 52 The attributes of IPL’s receivables sold under the Receivables Agreement were as follows (in millions): September 30, 2022 December 31, 2021 Customer accounts receivable $169 $125 Unbilled utility revenues 92 104 Receivables sold to third party 261 229 Less: cash proceeds 1 1 Deferred proceeds 260 228 Less: allowance for expected credit losses 12 14 Fair value of deferred proceeds $248 $214 As of September 30, 2022, outstanding receivables past due under the Receivables Agreement were $20 million. Additional attributes of IPL’s receivables sold under the Receivables Agreement for the three and nine months ended September 30 were as follows (in millions): Three Months Nine Months 2022 2021 2022 2021 Collections $670 $607 $1,731 $1,589 Write-offs, net of recoveries 3 4 6 7
IPL [Member]
Receivables [Line Items]
Receivables	RECEIVABLES Sales of Accounts Receivable - IPL maintains a Receivables Purchase and Sale Agreement (Receivables Agreement) whereby it may sell its customer accounts receivables, unbilled revenues and certain other accounts receivables to a third party through wholly-owned and consolidated special purpose entities. The transfers of receivables meet the criteria for sale accounting established by the transfer of financial assets accounting rules. As of September 30, 2022, IPL had $109 million of available capacity under its sales of accounts receivable program. IPL’s maximum and average outstanding cash proceeds (based on daily outstanding balances) related to the sales of accounts receivable program for the three and nine months ended September 30 were as follows (in millions): Three Months Nine Months 2022 2021 2022 2021 Maximum outstanding aggregate cash proceeds $36 $110 $66 $110 Average outstanding aggregate cash proceeds 3 65 8 52 The attributes of IPL’s receivables sold under the Receivables Agreement were as follows (in millions): September 30, 2022 December 31, 2021 Customer accounts receivable $169 $125 Unbilled utility revenues 92 104 Receivables sold to third party 261 229 Less: cash proceeds 1 1 Deferred proceeds 260 228 Less: allowance for expected credit losses 12 14 Fair value of deferred proceeds $248 $214 As of September 30, 2022, outstanding receivables past due under the Receivables Agreement were $20 million. Additional attributes of IPL’s receivables sold under the Receivables Agreement for the three and nine months ended September 30 were as follows (in millions): Three Months Nine Months 2022 2021 2022 2021 Collections $670 $607 $1,731 $1,589 Write-offs, net of recoveries 3 4 6 7

Investments

Investments	9 Months Ended
	Sep. 30, 2022
Schedule of Equity Method Investments [Line Items]
Investments	INVESTMENTS Unconsolidated Equity Investments - Alliant Energy’s equity (income) loss from unconsolidated investments accounted for under the equity method of accounting for the three and nine months ended September 30 was as follows (in millions): Three Months Nine Months 2022 2021 2022 2021 ATC Holdings ($7) ($12) ($29) ($34) Other 2 (1) (8) (13) ($5) ($13) ($37) ($47) Refer to N ote 13( e ) for discussion of a reduction in earnings recorded in the third quarter of 2022 related to a court decision, which is currently expected to reduce the base return on equity authorized for MISO transmission owners, including ATC.

Common Equity

Common Equity	9 Months Ended
	Sep. 30, 2022
Common Equity [Line Items]
Common Equity	COMMON EQUITY Common Share Activity - A summary of Alliant Energy’s common stock activity was as follows: Shares outstanding, January 1, 2022 250,474,529 Shareowner Direct Plan 324,533 Equity-based compensation plans 222,768 Shares outstanding, September 30, 2022 251,021,830 Noncontrolling Interest - In the second quarter of 2022, WPL and the tax equity partner contributed to a joint venture associated with certain WPL solar generation projects. The tax equity partner's contributions were represented as a noncontrolling interest within total equity on Alliant Energy’s and WPL’s balance sheets as of June 30, 2022. In the third quarter of 2022, WPL and the tax equity partner terminated the tax equity partnership and WPL returned the tax equity partner’s initial contributions, resulting in the reversal of the noncontrolling interest within total equity on Alliant Energy’s and WPL’s balance sheets as of September 30, 2022. Refer to Note 1( c ) for additional information. Changes in Shareowners’ Equity - A summary of changes in shareowners’ equity was as follows (in millions): Alliant Energy Total Alliant Energy Common Equity Accumulated Shares in Additional Other Deferred Common Paid-In Retained Comprehensive Compensation Noncontrolling Total Stock Capital Earnings Loss Trust Interest Equity Three Months Ended September 30, 2022 Beginning balance, June 30, 2022 $3 $2,759 $3,387 $— ($12) $29 $6,166 Net income attributable to Alliant Energy common shareowners 227 227 Common stock dividends ($0.4275 per share) (106) (106) Shareowner Direct Plan issuances 6 6 Equity-based compensation plans and other 2 (1) 1 Distributions to noncontrolling interest (29) (29) Ending balance, September 30, 2022 $3 $2,767 $3,508 $— ($13) $— $6,265 Alliant Energy Total Alliant Energy Common Equity Accumulated Shares in Cumulative Additional Other Deferred Preferred Common Paid-In Retained Comprehensive Compensation Stock Total Stock Capital Earnings Loss Trust of IPL Equity Three Months Ended September 30, 2021 Beginning balance, June 30, 2021 $3 $2,722 $3,106 ($1) ($11) $200 $6,019 Net income attributable to Alliant Energy common shareowners 256 256 Common stock dividends ($0.4025 per share) (101) (101) Shareowner Direct Plan issuances 6 6 Equity-based compensation plans and other 5 5 Ending balance, September 30, 2021 $3 $2,733 $3,261 ($1) ($11) $200 $6,185 Alliant Energy Total Alliant Energy Common Equity Accumulated Shares in Additional Other Deferred Common Paid-In Retained Comprehensive Compensation Noncontrolling Total Stock Capital Earnings Loss Trust Interest Equity Nine Months Ended September 30, 2022 Beginning balance, December 31, 2021 $3 $2,749 $3,250 $— ($12) $— $5,990 Net income attributable to Alliant Energy common shareowners 579 579 Common stock dividends ($1.2825 per share) (322) (322) Shareowner Direct Plan issuances 19 19 Equity-based compensation plans and other (1) 1 (1) (1) Contributions from noncontrolling interest 29 29 Distributions to noncontrolling interest (29) (29) Ending balance, September 30, 2022 $3 $2,767 $3,508 $— ($13) $— $6,265 Alliant Energy Total Alliant Energy Common Equity Accumulated Shares in Cumulative Additional Other Deferred Preferred Common Paid-In Retained Comprehensive Compensation Stock Total Stock Capital Earnings Loss Trust of IPL Equity Nine Months Ended September 30, 2021 Beginning balance, December 31, 2020 $2 $2,704 $2,994 ($1) ($11) $200 $5,888 Net income attributable to Alliant Energy common shareowners 571 571 Common stock dividends ($1.2075 per share) (304) (304) Shareowner Direct Plan issuances 1 21 22 Equity-based compensation plans and other 8 8 Ending balance, September 30, 2021 $3 $2,733 $3,261 ($1) ($11) $200 $6,185 IPL Total IPL Common Equity Additional Cumulative Common Paid-In Retained Preferred Total Stock Capital Earnings Stock Equity Three Months Ended September 30, 2022 Beginning balance, June 30, 2022 $33 $2,807 $942 $— $3,782 Net income available for common stock 154 154 Common stock dividends (80) (80) Ending balance, September 30, 2022 $33 $2,807 $1,016 $— $3,856 Three Months Ended September 30, 2021 Beginning balance, June 30, 2021 $33 $2,802 $944 $200 $3,979 Net income available for common stock 157 157 Common stock dividends (101) (101) Ending balance, September 30, 2021 $33 $2,802 $1,000 $200 $4,035 IPL Total IPL Common Equity Additional Cumulative Common Paid-In Retained Preferred Total Stock Capital Earnings Stock Equity Nine Months Ended September 30, 2022 Beginning balance, December 31, 2021 $33 $2,807 $929 $— $3,769 Net income available for common stock 327 327 Common stock dividends (240) (240) Ending balance, September 30, 2022 $33 $2,807 $1,016 $— $3,856 Nine Months Ended September 30, 2021 Beginning balance, December 31, 2020 $33 $2,752 $979 $200 $3,964 Net income available for common stock 322 322 Common stock dividends (301) (301) Capital contributions from parent 50 50 Ending balance, September 30, 2021 $33 $2,802 $1,000 $200 $4,035 WPL Total WPL Common Equity Additional Common Paid-In Retained Noncontrolling Total Stock Capital Earnings Interest Equity Three Months Ended September 30, 2022 Beginning balance, June 30, 2022 $66 $1,968 $1,120 $29 $3,183 Net income 91 91 Common stock dividends (44) (44) Capital contributions from parent 155 155 Distributions to noncontrolling interest (29) (29) Ending balance, September 30, 2022 $66 $2,123 $1,167 $— $3,356 Three Months Ended September 30, 2021 Beginning balance, June 30, 2021 $66 $1,669 $990 $— $2,725 Net income 93 93 Common stock dividends (41) (41) Capital contributions from parent 35 35 Ending balance, September 30, 2021 $66 $1,704 $1,042 $— $2,812 WPL Total WPL Common Equity Additional Common Paid-In Retained Noncontrolling Total Stock Capital Earnings Interest Equity Nine Months Ended September 30, 2022 Beginning balance, December 31, 2021 $66 $1,704 $1,053 $— $2,823 Net income 247 247 Common stock dividends (133) (133) Capital contributions from parent 420 420 Contributions from noncontrolling interest 29 29 Distributions to noncontrolling interest (29) (29) Other (1) (1) Ending balance, September 30, 2022 $66 $2,123 $1,167 $— $3,356 Nine Months Ended September 30, 2021 Beginning balance, December 31, 2020 $66 $1,459 $953 $— $2,478 Net income 215 215 Common stock dividends (126) (126) Capital contributions from parent 245 245 Ending balance, September 30, 2021 $66 $1,704 $1,042 $— $2,812
IPL [Member]
Common Equity [Line Items]
Common Equity	COMMON EQUITY Common Share Activity - A summary of Alliant Energy’s common stock activity was as follows: Shares outstanding, January 1, 2022 250,474,529 Shareowner Direct Plan 324,533 Equity-based compensation plans 222,768 Shares outstanding, September 30, 2022 251,021,830 Noncontrolling Interest - In the second quarter of 2022, WPL and the tax equity partner contributed to a joint venture associated with certain WPL solar generation projects. The tax equity partner's contributions were represented as a noncontrolling interest within total equity on Alliant Energy’s and WPL’s balance sheets as of June 30, 2022. In the third quarter of 2022, WPL and the tax equity partner terminated the tax equity partnership and WPL returned the tax equity partner’s initial contributions, resulting in the reversal of the noncontrolling interest within total equity on Alliant Energy’s and WPL’s balance sheets as of September 30, 2022. Refer to Note 1( c ) for additional information. Changes in Shareowners’ Equity - A summary of changes in shareowners’ equity was as follows (in millions): Alliant Energy Total Alliant Energy Common Equity Accumulated Shares in Additional Other Deferred Common Paid-In Retained Comprehensive Compensation Noncontrolling Total Stock Capital Earnings Loss Trust Interest Equity Three Months Ended September 30, 2022 Beginning balance, June 30, 2022 $3 $2,759 $3,387 $— ($12) $29 $6,166 Net income attributable to Alliant Energy common shareowners 227 227 Common stock dividends ($0.4275 per share) (106) (106) Shareowner Direct Plan issuances 6 6 Equity-based compensation plans and other 2 (1) 1 Distributions to noncontrolling interest (29) (29) Ending balance, September 30, 2022 $3 $2,767 $3,508 $— ($13) $— $6,265 Alliant Energy Total Alliant Energy Common Equity Accumulated Shares in Cumulative Additional Other Deferred Preferred Common Paid-In Retained Comprehensive Compensation Stock Total Stock Capital Earnings Loss Trust of IPL Equity Three Months Ended September 30, 2021 Beginning balance, June 30, 2021 $3 $2,722 $3,106 ($1) ($11) $200 $6,019 Net income attributable to Alliant Energy common shareowners 256 256 Common stock dividends ($0.4025 per share) (101) (101) Shareowner Direct Plan issuances 6 6 Equity-based compensation plans and other 5 5 Ending balance, September 30, 2021 $3 $2,733 $3,261 ($1) ($11) $200 $6,185 Alliant Energy Total Alliant Energy Common Equity Accumulated Shares in Additional Other Deferred Common Paid-In Retained Comprehensive Compensation Noncontrolling Total Stock Capital Earnings Loss Trust Interest Equity Nine Months Ended September 30, 2022 Beginning balance, December 31, 2021 $3 $2,749 $3,250 $— ($12) $— $5,990 Net income attributable to Alliant Energy common shareowners 579 579 Common stock dividends ($1.2825 per share) (322) (322) Shareowner Direct Plan issuances 19 19 Equity-based compensation plans and other (1) 1 (1) (1) Contributions from noncontrolling interest 29 29 Distributions to noncontrolling interest (29) (29) Ending balance, September 30, 2022 $3 $2,767 $3,508 $— ($13) $— $6,265 Alliant Energy Total Alliant Energy Common Equity Accumulated Shares in Cumulative Additional Other Deferred Preferred Common Paid-In Retained Comprehensive Compensation Stock Total Stock Capital Earnings Loss Trust of IPL Equity Nine Months Ended September 30, 2021 Beginning balance, December 31, 2020 $2 $2,704 $2,994 ($1) ($11) $200 $5,888 Net income attributable to Alliant Energy common shareowners 571 571 Common stock dividends ($1.2075 per share) (304) (304) Shareowner Direct Plan issuances 1 21 22 Equity-based compensation plans and other 8 8 Ending balance, September 30, 2021 $3 $2,733 $3,261 ($1) ($11) $200 $6,185 IPL Total IPL Common Equity Additional Cumulative Common Paid-In Retained Preferred Total Stock Capital Earnings Stock Equity Three Months Ended September 30, 2022 Beginning balance, June 30, 2022 $33 $2,807 $942 $— $3,782 Net income available for common stock 154 154 Common stock dividends (80) (80) Ending balance, September 30, 2022 $33 $2,807 $1,016 $— $3,856 Three Months Ended September 30, 2021 Beginning balance, June 30, 2021 $33 $2,802 $944 $200 $3,979 Net income available for common stock 157 157 Common stock dividends (101) (101) Ending balance, September 30, 2021 $33 $2,802 $1,000 $200 $4,035 IPL Total IPL Common Equity Additional Cumulative Common Paid-In Retained Preferred Total Stock Capital Earnings Stock Equity Nine Months Ended September 30, 2022 Beginning balance, December 31, 2021 $33 $2,807 $929 $— $3,769 Net income available for common stock 327 327 Common stock dividends (240) (240) Ending balance, September 30, 2022 $33 $2,807 $1,016 $— $3,856 Nine Months Ended September 30, 2021 Beginning balance, December 31, 2020 $33 $2,752 $979 $200 $3,964 Net income available for common stock 322 322 Common stock dividends (301) (301) Capital contributions from parent 50 50 Ending balance, September 30, 2021 $33 $2,802 $1,000 $200 $4,035 WPL Total WPL Common Equity Additional Common Paid-In Retained Noncontrolling Total Stock Capital Earnings Interest Equity Three Months Ended September 30, 2022 Beginning balance, June 30, 2022 $66 $1,968 $1,120 $29 $3,183 Net income 91 91 Common stock dividends (44) (44) Capital contributions from parent 155 155 Distributions to noncontrolling interest (29) (29) Ending balance, September 30, 2022 $66 $2,123 $1,167 $— $3,356 Three Months Ended September 30, 2021 Beginning balance, June 30, 2021 $66 $1,669 $990 $— $2,725 Net income 93 93 Common stock dividends (41) (41) Capital contributions from parent 35 35 Ending balance, September 30, 2021 $66 $1,704 $1,042 $— $2,812 WPL Total WPL Common Equity Additional Common Paid-In Retained Noncontrolling Total Stock Capital Earnings Interest Equity Nine Months Ended September 30, 2022 Beginning balance, December 31, 2021 $66 $1,704 $1,053 $— $2,823 Net income 247 247 Common stock dividends (133) (133) Capital contributions from parent 420 420 Contributions from noncontrolling interest 29 29 Distributions to noncontrolling interest (29) (29) Other (1) (1) Ending balance, September 30, 2022 $66 $2,123 $1,167 $— $3,356 Nine Months Ended September 30, 2021 Beginning balance, December 31, 2020 $66 $1,459 $953 $— $2,478 Net income 215 215 Common stock dividends (126) (126) Capital contributions from parent 245 245 Ending balance, September 30, 2021 $66 $1,704 $1,042 $— $2,812
WPL [Member]
Common Equity [Line Items]
Common Equity	COMMON EQUITY Common Share Activity - A summary of Alliant Energy’s common stock activity was as follows: Shares outstanding, January 1, 2022 250,474,529 Shareowner Direct Plan 324,533 Equity-based compensation plans 222,768 Shares outstanding, September 30, 2022 251,021,830 Noncontrolling Interest - In the second quarter of 2022, WPL and the tax equity partner contributed to a joint venture associated with certain WPL solar generation projects. The tax equity partner's contributions were represented as a noncontrolling interest within total equity on Alliant Energy’s and WPL’s balance sheets as of June 30, 2022. In the third quarter of 2022, WPL and the tax equity partner terminated the tax equity partnership and WPL returned the tax equity partner’s initial contributions, resulting in the reversal of the noncontrolling interest within total equity on Alliant Energy’s and WPL’s balance sheets as of September 30, 2022. Refer to Note 1( c ) for additional information. Changes in Shareowners’ Equity - A summary of changes in shareowners’ equity was as follows (in millions): Alliant Energy Total Alliant Energy Common Equity Accumulated Shares in Additional Other Deferred Common Paid-In Retained Comprehensive Compensation Noncontrolling Total Stock Capital Earnings Loss Trust Interest Equity Three Months Ended September 30, 2022 Beginning balance, June 30, 2022 $3 $2,759 $3,387 $— ($12) $29 $6,166 Net income attributable to Alliant Energy common shareowners 227 227 Common stock dividends ($0.4275 per share) (106) (106) Shareowner Direct Plan issuances 6 6 Equity-based compensation plans and other 2 (1) 1 Distributions to noncontrolling interest (29) (29) Ending balance, September 30, 2022 $3 $2,767 $3,508 $— ($13) $— $6,265 Alliant Energy Total Alliant Energy Common Equity Accumulated Shares in Cumulative Additional Other Deferred Preferred Common Paid-In Retained Comprehensive Compensation Stock Total Stock Capital Earnings Loss Trust of IPL Equity Three Months Ended September 30, 2021 Beginning balance, June 30, 2021 $3 $2,722 $3,106 ($1) ($11) $200 $6,019 Net income attributable to Alliant Energy common shareowners 256 256 Common stock dividends ($0.4025 per share) (101) (101) Shareowner Direct Plan issuances 6 6 Equity-based compensation plans and other 5 5 Ending balance, September 30, 2021 $3 $2,733 $3,261 ($1) ($11) $200 $6,185 Alliant Energy Total Alliant Energy Common Equity Accumulated Shares in Additional Other Deferred Common Paid-In Retained Comprehensive Compensation Noncontrolling Total Stock Capital Earnings Loss Trust Interest Equity Nine Months Ended September 30, 2022 Beginning balance, December 31, 2021 $3 $2,749 $3,250 $— ($12) $— $5,990 Net income attributable to Alliant Energy common shareowners 579 579 Common stock dividends ($1.2825 per share) (322) (322) Shareowner Direct Plan issuances 19 19 Equity-based compensation plans and other (1) 1 (1) (1) Contributions from noncontrolling interest 29 29 Distributions to noncontrolling interest (29) (29) Ending balance, September 30, 2022 $3 $2,767 $3,508 $— ($13) $— $6,265 Alliant Energy Total Alliant Energy Common Equity Accumulated Shares in Cumulative Additional Other Deferred Preferred Common Paid-In Retained Comprehensive Compensation Stock Total Stock Capital Earnings Loss Trust of IPL Equity Nine Months Ended September 30, 2021 Beginning balance, December 31, 2020 $2 $2,704 $2,994 ($1) ($11) $200 $5,888 Net income attributable to Alliant Energy common shareowners 571 571 Common stock dividends ($1.2075 per share) (304) (304) Shareowner Direct Plan issuances 1 21 22 Equity-based compensation plans and other 8 8 Ending balance, September 30, 2021 $3 $2,733 $3,261 ($1) ($11) $200 $6,185 IPL Total IPL Common Equity Additional Cumulative Common Paid-In Retained Preferred Total Stock Capital Earnings Stock Equity Three Months Ended September 30, 2022 Beginning balance, June 30, 2022 $33 $2,807 $942 $— $3,782 Net income available for common stock 154 154 Common stock dividends (80) (80) Ending balance, September 30, 2022 $33 $2,807 $1,016 $— $3,856 Three Months Ended September 30, 2021 Beginning balance, June 30, 2021 $33 $2,802 $944 $200 $3,979 Net income available for common stock 157 157 Common stock dividends (101) (101) Ending balance, September 30, 2021 $33 $2,802 $1,000 $200 $4,035 IPL Total IPL Common Equity Additional Cumulative Common Paid-In Retained Preferred Total Stock Capital Earnings Stock Equity Nine Months Ended September 30, 2022 Beginning balance, December 31, 2021 $33 $2,807 $929 $— $3,769 Net income available for common stock 327 327 Common stock dividends (240) (240) Ending balance, September 30, 2022 $33 $2,807 $1,016 $— $3,856 Nine Months Ended September 30, 2021 Beginning balance, December 31, 2020 $33 $2,752 $979 $200 $3,964 Net income available for common stock 322 322 Common stock dividends (301) (301) Capital contributions from parent 50 50 Ending balance, September 30, 2021 $33 $2,802 $1,000 $200 $4,035 WPL Total WPL Common Equity Additional Common Paid-In Retained Noncontrolling Total Stock Capital Earnings Interest Equity Three Months Ended September 30, 2022 Beginning balance, June 30, 2022 $66 $1,968 $1,120 $29 $3,183 Net income 91 91 Common stock dividends (44) (44) Capital contributions from parent 155 155 Distributions to noncontrolling interest (29) (29) Ending balance, September 30, 2022 $66 $2,123 $1,167 $— $3,356 Three Months Ended September 30, 2021 Beginning balance, June 30, 2021 $66 $1,669 $990 $— $2,725 Net income 93 93 Common stock dividends (41) (41) Capital contributions from parent 35 35 Ending balance, September 30, 2021 $66 $1,704 $1,042 $— $2,812 WPL Total WPL Common Equity Additional Common Paid-In Retained Noncontrolling Total Stock Capital Earnings Interest Equity Nine Months Ended September 30, 2022 Beginning balance, December 31, 2021 $66 $1,704 $1,053 $— $2,823 Net income 247 247 Common stock dividends (133) (133) Capital contributions from parent 420 420 Contributions from noncontrolling interest 29 29 Distributions to noncontrolling interest (29) (29) Other (1) (1) Ending balance, September 30, 2022 $66 $2,123 $1,167 $— $3,356 Nine Months Ended September 30, 2021 Beginning balance, December 31, 2020 $66 $1,459 $953 $— $2,478 Net income 215 215 Common stock dividends (126) (126) Capital contributions from parent 245 245 Ending balance, September 30, 2021 $66 $1,704 $1,042 $— $2,812

Debt

Debt	9 Months Ended
	Sep. 30, 2022
Debt [Line Items]
Debt	DEBT NOTE 7(a) Short-term Debt - Information regarding Alliant Energy’s, IPL’s and WPL’s commercial paper classified as short-term debt was as follows (dollars in millions): September 30, 2022 Alliant Energy IPL WPL Amount outstanding $383 $— $— Weighted average interest rates 3.4% N/A N/A Available credit facility capacity $617 $250 $300 Alliant Energy IPL WPL Three Months Ended September 30 2022 2021 2022 2021 2022 2021 Maximum amount outstanding (based on daily outstanding balances) $449 $648 $— $8 $251 $320 Average amount outstanding (based on daily outstanding balances) $353 $560 $— $— $110 $221 Weighted average interest rates 2.4% 0.2% —% 0.2% 2.0% 0.1% Nine Months Ended September 30 Maximum amount outstanding (based on daily outstanding balances) $577 $648 $— $19 $252 $320 Average amount outstanding (based on daily outstanding balances) $377 $479 $— $— $160 $196 Weighted average interest rates 1.2% 0.2% —% 0.2% 0.9% 0.1% In October 2022, Alliant Energy, IPL and WPL reallocated credit facility capacity amounts to $500 million for Alliant Energy at the parent company level, $200 million for IPL and $300 million for WPL, within the $1 billion total commitment. NOTE 7(b) Long-term Debt - In February 2022, AEF issued $350 million of 3.6% senior notes due 2032. The net proceeds from the issuance were used to reduce Alliant Energy’s outstanding commercial paper and for general corporate purposes. In March 2022, AEF entered into a $300 million variable rate (3% as of September 30, 2022) term loan credit agreement (with Alliant Energy as guarantor), which expires in March 2024, and used the borrowings under this agreement to retire its $300 million variable rate term loan credit agreement that expired in March 2022. In August 2022, WPL issued $600 million of 3.95% debentures due 2032. The debentures were issued as green bonds, and an amount equal to or in excess of the net proceeds will be disbursed for the development and acquisition of WPL’s solar EGUs. In September 2022, Corporate Services retired its $75 million, 3.45% senior notes due 2022.
IPL [Member]
Debt [Line Items]
Debt	DEBT NOTE 7(a) Short-term Debt - Information regarding Alliant Energy’s, IPL’s and WPL’s commercial paper classified as short-term debt was as follows (dollars in millions): September 30, 2022 Alliant Energy IPL WPL Amount outstanding $383 $— $— Weighted average interest rates 3.4% N/A N/A Available credit facility capacity $617 $250 $300 Alliant Energy IPL WPL Three Months Ended September 30 2022 2021 2022 2021 2022 2021 Maximum amount outstanding (based on daily outstanding balances) $449 $648 $— $8 $251 $320 Average amount outstanding (based on daily outstanding balances) $353 $560 $— $— $110 $221 Weighted average interest rates 2.4% 0.2% —% 0.2% 2.0% 0.1% Nine Months Ended September 30 Maximum amount outstanding (based on daily outstanding balances) $577 $648 $— $19 $252 $320 Average amount outstanding (based on daily outstanding balances) $377 $479 $— $— $160 $196 Weighted average interest rates 1.2% 0.2% —% 0.2% 0.9% 0.1% In October 2022, Alliant Energy, IPL and WPL reallocated credit facility capacity amounts to $500 million for Alliant Energy at the parent company level, $200 million for IPL and $300 million for WPL, within the $1 billion total commitment.
WPL [Member]
Debt [Line Items]
Debt	DEBT NOTE 7(a) Short-term Debt - Information regarding Alliant Energy’s, IPL’s and WPL’s commercial paper classified as short-term debt was as follows (dollars in millions): September 30, 2022 Alliant Energy IPL WPL Amount outstanding $383 $— $— Weighted average interest rates 3.4% N/A N/A Available credit facility capacity $617 $250 $300 Alliant Energy IPL WPL Three Months Ended September 30 2022 2021 2022 2021 2022 2021 Maximum amount outstanding (based on daily outstanding balances) $449 $648 $— $8 $251 $320 Average amount outstanding (based on daily outstanding balances) $353 $560 $— $— $110 $221 Weighted average interest rates 2.4% 0.2% —% 0.2% 2.0% 0.1% Nine Months Ended September 30 Maximum amount outstanding (based on daily outstanding balances) $577 $648 $— $19 $252 $320 Average amount outstanding (based on daily outstanding balances) $377 $479 $— $— $160 $196 Weighted average interest rates 1.2% 0.2% —% 0.2% 0.9% 0.1% In October 2022, Alliant Energy, IPL and WPL reallocated credit facility capacity amounts to $500 million for Alliant Energy at the parent company level, $200 million for IPL and $300 million for WPL, within the $1 billion total commitment. NOTE 7(b) Long-term Debt - In February 2022, AEF issued $350 million of 3.6% senior notes due 2032. The net proceeds from the issuance were used to reduce Alliant Energy’s outstanding commercial paper and for general corporate purposes. In March 2022, AEF entered into a $300 million variable rate (3% as of September 30, 2022) term loan credit agreement (with Alliant Energy as guarantor), which expires in March 2024, and used the borrowings under this agreement to retire its $300 million variable rate term loan credit agreement that expired in March 2022. In August 2022, WPL issued $600 million of 3.95% debentures due 2032. The debentures were issued as green bonds, and an amount equal to or in excess of the net proceeds will be disbursed for the development and acquisition of WPL’s solar EGUs. In September 2022, Corporate Services retired its $75 million, 3.45% senior notes due 2022.

Revenues

Revenues	9 Months Ended
	Sep. 30, 2022
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	REVENUES Disaggregation of revenues from contracts with customers, which correlates to revenues for each reportable segment, was as follows (in millions): Alliant Energy IPL WPL Three Months Ended September 30 2022 2021 2022 2021 2022 2021 Electric Utility: Retail - residential $376 $348 $222 $207 $154 $141 Retail - commercial 243 232 165 160 78 72 Retail - industrial 289 265 172 158 117 107 Wholesale 68 55 19 18 49 37 Bulk power and other 63 39 18 12 45 27 Total Electric Utility 1,039 939 596 555 443 384 Gas Utility: Retail - residential 28 24 14 14 14 10 Retail - commercial 18 13 8 8 10 5 Retail - industrial 4 3 3 3 1 — Transportation/other 12 10 8 6 4 4 Total Gas Utility 62 50 33 31 29 19 Other Utility: Steam 9 9 9 9 — — Other utility 2 4 2 4 — — Total Other Utility 11 13 11 13 — — Non-Utility and Other: Travero and other 23 22 — — — — Total Non-Utility and Other 23 22 — — — — Total revenues $1,135 $1,024 $640 $599 $472 $403 Alliant Energy IPL WPL Nine Months Ended September 30 2022 2021 2022 2021 2022 2021 Electric Utility: Retail - residential $956 $868 $529 $488 $427 $380 Retail - commercial 628 579 411 385 217 194 Retail - industrial 743 677 418 386 325 291 Wholesale 168 142 49 44 119 98 Bulk power and other 129 91 31 40 98 51 Total Electric Utility 2,624 2,357 1,438 1,343 1,186 1,014 Gas Utility: Retail - residential 237 162 127 90 110 72 Retail - commercial 127 85 62 47 65 38 Retail - industrial 15 11 10 8 5 3 Transportation/other 39 31 25 20 14 11 Total Gas Utility 418 289 224 165 194 124 Other Utility: Steam 29 27 29 27 — — Other utility 6 9 5 8 1 1 Total Other Utility 35 36 34 35 1 1 Non-Utility and Other: Travero and other 70 60 — — — — Total Non-Utility and Other 70 60 — — — — Total revenues $3,147 $2,742 $1,696 $1,543 $1,381 $1,139
IPL [Member]
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	REVENUES Disaggregation of revenues from contracts with customers, which correlates to revenues for each reportable segment, was as follows (in millions): Alliant Energy IPL WPL Three Months Ended September 30 2022 2021 2022 2021 2022 2021 Electric Utility: Retail - residential $376 $348 $222 $207 $154 $141 Retail - commercial 243 232 165 160 78 72 Retail - industrial 289 265 172 158 117 107 Wholesale 68 55 19 18 49 37 Bulk power and other 63 39 18 12 45 27 Total Electric Utility 1,039 939 596 555 443 384 Gas Utility: Retail - residential 28 24 14 14 14 10 Retail - commercial 18 13 8 8 10 5 Retail - industrial 4 3 3 3 1 — Transportation/other 12 10 8 6 4 4 Total Gas Utility 62 50 33 31 29 19 Other Utility: Steam 9 9 9 9 — — Other utility 2 4 2 4 — — Total Other Utility 11 13 11 13 — — Non-Utility and Other: Travero and other 23 22 — — — — Total Non-Utility and Other 23 22 — — — — Total revenues $1,135 $1,024 $640 $599 $472 $403 Alliant Energy IPL WPL Nine Months Ended September 30 2022 2021 2022 2021 2022 2021 Electric Utility: Retail - residential $956 $868 $529 $488 $427 $380 Retail - commercial 628 579 411 385 217 194 Retail - industrial 743 677 418 386 325 291 Wholesale 168 142 49 44 119 98 Bulk power and other 129 91 31 40 98 51 Total Electric Utility 2,624 2,357 1,438 1,343 1,186 1,014 Gas Utility: Retail - residential 237 162 127 90 110 72 Retail - commercial 127 85 62 47 65 38 Retail - industrial 15 11 10 8 5 3 Transportation/other 39 31 25 20 14 11 Total Gas Utility 418 289 224 165 194 124 Other Utility: Steam 29 27 29 27 — — Other utility 6 9 5 8 1 1 Total Other Utility 35 36 34 35 1 1 Non-Utility and Other: Travero and other 70 60 — — — — Total Non-Utility and Other 70 60 — — — — Total revenues $3,147 $2,742 $1,696 $1,543 $1,381 $1,139
WPL [Member]
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	REVENUES Disaggregation of revenues from contracts with customers, which correlates to revenues for each reportable segment, was as follows (in millions): Alliant Energy IPL WPL Three Months Ended September 30 2022 2021 2022 2021 2022 2021 Electric Utility: Retail - residential $376 $348 $222 $207 $154 $141 Retail - commercial 243 232 165 160 78 72 Retail - industrial 289 265 172 158 117 107 Wholesale 68 55 19 18 49 37 Bulk power and other 63 39 18 12 45 27 Total Electric Utility 1,039 939 596 555 443 384 Gas Utility: Retail - residential 28 24 14 14 14 10 Retail - commercial 18 13 8 8 10 5 Retail - industrial 4 3 3 3 1 — Transportation/other 12 10 8 6 4 4 Total Gas Utility 62 50 33 31 29 19 Other Utility: Steam 9 9 9 9 — — Other utility 2 4 2 4 — — Total Other Utility 11 13 11 13 — — Non-Utility and Other: Travero and other 23 22 — — — — Total Non-Utility and Other 23 22 — — — — Total revenues $1,135 $1,024 $640 $599 $472 $403 Alliant Energy IPL WPL Nine Months Ended September 30 2022 2021 2022 2021 2022 2021 Electric Utility: Retail - residential $956 $868 $529 $488 $427 $380 Retail - commercial 628 579 411 385 217 194 Retail - industrial 743 677 418 386 325 291 Wholesale 168 142 49 44 119 98 Bulk power and other 129 91 31 40 98 51 Total Electric Utility 2,624 2,357 1,438 1,343 1,186 1,014 Gas Utility: Retail - residential 237 162 127 90 110 72 Retail - commercial 127 85 62 47 65 38 Retail - industrial 15 11 10 8 5 3 Transportation/other 39 31 25 20 14 11 Total Gas Utility 418 289 224 165 194 124 Other Utility: Steam 29 27 29 27 — — Other utility 6 9 5 8 1 1 Total Other Utility 35 36 34 35 1 1 Non-Utility and Other: Travero and other 70 60 — — — — Total Non-Utility and Other 70 60 — — — — Total revenues $3,147 $2,742 $1,696 $1,543 $1,381 $1,139

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2022
Income Taxes [Line Items]
Income Taxes	INCOME TAXES Income Tax Rates - Overall effective income tax rates, which were computed by dividing income tax expense (benefit) by income before income taxes, were as follows. The effective income tax rates were different than the federal statutory rate primarily due to state income taxes, production tax credits, amortization of excess deferred taxes and the effect of rate-making on property-related differences. The increases in Alliant Energy’s and WPL’s overall effective income tax rates for the three and nine months ended September 30, 2022 compared to the same periods in 2021 were primarily due to decreased amortization of excess deferred taxes primarily at WPL. Alliant Energy IPL WPL Three Months Nine Months Three Months Nine Months Three Months Nine Months 2022 2021 2022 2021 2022 2021 2022 2021 2022 2021 2022 2021 Overall income tax rate 6% (9%) 4% (13%) (12%) (8%) (14%) (11%) 15% (19%) 17% (24%) Deferred Tax Assets and Liabilities - Carryforwards - In the third quarter of 2022, Alliant Energy, IPL and WPL fully utilized their respective federal net operating losses carryforwards. At September 30, 2022, the remaining carryforwards and expiration dates were estimated as follows (in millions): Range of Expiration Dates Alliant Energy IPL WPL State net operating losses 2022-2042 $500 $9 $2 Federal tax credits 2022-2042 655 437 208 Iowa Tax Reform - In March 2022, Iowa tax reform was enacted. Annually, and by each November 1, the Iowa Department of Revenue will establish corporate income tax rates for the next tax year based on net corporate income tax receipts for the prior tax year, and reduce such rates if certain state income tax revenue triggers are satisfied. These corporate income tax rate reductions are currently expected to occur over a period of several years, with a target corporate income tax rate of 5.5%, compared to the current 9.8% Iowa corporate income tax rate. In September 2022, the Iowa Department of Revenue announced an Iowa corporate income tax rate of 8.4%, effective January 1, 2023. Deferred tax assets and liabilities are measured at the enacted tax rate expected to be applied when temporary differences are to be realized or settled. Given the announcement of the new Iowa corporate income tax rate, Alliant Energy’s and IPL’s deferred tax liabilities were remeasured based upon the new rate effective January 1, 2023, which resulted in a $76 million reduction of Alliant Energy’s and IPL’s tax-related regulatory assets and a decrease in their deferred tax liabilities in the third quarter of 2022. The reduction in tax-related regulatory assets is expected to provide cost benefits to IPL’s customers in the future. Alliant Energy parent company’s deferred tax assets were remeasured based upon the new rate effective January 1, 2023, which resulted in a charge of $8 million recorded to income tax expense in Alliant Energy’s income statement and a decrease in deferred income tax assets on Alliant Energy’s balance sheet in the third quarter of 2022. Alliant Energy is currently unable to predict with certainty the timing or amount of any future rate reductions.
IPL [Member]
Income Taxes [Line Items]
Income Taxes	INCOME TAXES Income Tax Rates - Overall effective income tax rates, which were computed by dividing income tax expense (benefit) by income before income taxes, were as follows. The effective income tax rates were different than the federal statutory rate primarily due to state income taxes, production tax credits, amortization of excess deferred taxes and the effect of rate-making on property-related differences. The increases in Alliant Energy’s and WPL’s overall effective income tax rates for the three and nine months ended September 30, 2022 compared to the same periods in 2021 were primarily due to decreased amortization of excess deferred taxes primarily at WPL. Alliant Energy IPL WPL Three Months Nine Months Three Months Nine Months Three Months Nine Months 2022 2021 2022 2021 2022 2021 2022 2021 2022 2021 2022 2021 Overall income tax rate 6% (9%) 4% (13%) (12%) (8%) (14%) (11%) 15% (19%) 17% (24%) Deferred Tax Assets and Liabilities - Carryforwards - In the third quarter of 2022, Alliant Energy, IPL and WPL fully utilized their respective federal net operating losses carryforwards. At September 30, 2022, the remaining carryforwards and expiration dates were estimated as follows (in millions): Range of Expiration Dates Alliant Energy IPL WPL State net operating losses 2022-2042 $500 $9 $2 Federal tax credits 2022-2042 655 437 208 Iowa Tax Reform - In March 2022, Iowa tax reform was enacted. Annually, and by each November 1, the Iowa Department of Revenue will establish corporate income tax rates for the next tax year based on net corporate income tax receipts for the prior tax year, and reduce such rates if certain state income tax revenue triggers are satisfied. These corporate income tax rate reductions are currently expected to occur over a period of several years, with a target corporate income tax rate of 5.5%, compared to the current 9.8% Iowa corporate income tax rate. In September 2022, the Iowa Department of Revenue announced an Iowa corporate income tax rate of 8.4%, effective January 1, 2023. Deferred tax assets and liabilities are measured at the enacted tax rate expected to be applied when temporary differences are to be realized or settled. Given the announcement of the new Iowa corporate income tax rate, Alliant Energy’s and IPL’s deferred tax liabilities were remeasured based upon the new rate effective January 1, 2023, which resulted in a $76 million reduction of Alliant Energy’s and IPL’s tax-related regulatory assets and a decrease in their deferred tax liabilities in the third quarter of 2022. The reduction in tax-related regulatory assets is expected to provide cost benefits to IPL’s customers in the future. Alliant Energy parent company’s deferred tax assets were remeasured based upon the new rate effective January 1, 2023, which resulted in a charge of $8 million recorded to income tax expense in Alliant Energy’s income statement and a decrease in deferred income tax assets on Alliant Energy’s balance sheet in the third quarter of 2022. Alliant Energy is currently unable to predict with certainty the timing or amount of any future rate reductions.
WPL [Member]
Income Taxes [Line Items]
Income Taxes	INCOME TAXES Income Tax Rates - Overall effective income tax rates, which were computed by dividing income tax expense (benefit) by income before income taxes, were as follows. The effective income tax rates were different than the federal statutory rate primarily due to state income taxes, production tax credits, amortization of excess deferred taxes and the effect of rate-making on property-related differences. The increases in Alliant Energy’s and WPL’s overall effective income tax rates for the three and nine months ended September 30, 2022 compared to the same periods in 2021 were primarily due to decreased amortization of excess deferred taxes primarily at WPL. Alliant Energy IPL WPL Three Months Nine Months Three Months Nine Months Three Months Nine Months 2022 2021 2022 2021 2022 2021 2022 2021 2022 2021 2022 2021 Overall income tax rate 6% (9%) 4% (13%) (12%) (8%) (14%) (11%) 15% (19%) 17% (24%) Deferred Tax Assets and Liabilities - Carryforwards - In the third quarter of 2022, Alliant Energy, IPL and WPL fully utilized their respective federal net operating losses carryforwards. At September 30, 2022, the remaining carryforwards and expiration dates were estimated as follows (in millions): Range of Expiration Dates Alliant Energy IPL WPL State net operating losses 2022-2042 $500 $9 $2 Federal tax credits 2022-2042 655 437 208 Iowa Tax Reform - In March 2022, Iowa tax reform was enacted. Annually, and by each November 1, the Iowa Department of Revenue will establish corporate income tax rates for the next tax year based on net corporate income tax receipts for the prior tax year, and reduce such rates if certain state income tax revenue triggers are satisfied. These corporate income tax rate reductions are currently expected to occur over a period of several years, with a target corporate income tax rate of 5.5%, compared to the current 9.8% Iowa corporate income tax rate. In September 2022, the Iowa Department of Revenue announced an Iowa corporate income tax rate of 8.4%, effective January 1, 2023. Deferred tax assets and liabilities are measured at the enacted tax rate expected to be applied when temporary differences are to be realized or settled. Given the announcement of the new Iowa corporate income tax rate, Alliant Energy’s and IPL’s deferred tax liabilities were remeasured based upon the new rate effective January 1, 2023, which resulted in a $76 million reduction of Alliant Energy’s and IPL’s tax-related regulatory assets and a decrease in their deferred tax liabilities in the third quarter of 2022. The reduction in tax-related regulatory assets is expected to provide cost benefits to IPL’s customers in the future. Alliant Energy parent company’s deferred tax assets were remeasured based upon the new rate effective January 1, 2023, which resulted in a charge of $8 million recorded to income tax expense in Alliant Energy’s income statement and a decrease in deferred income tax assets on Alliant Energy’s balance sheet in the third quarter of 2022. Alliant Energy is currently unable to predict with certainty the timing or amount of any future rate reductions.

Benefit Plans

Benefit Plans	9 Months Ended
	Sep. 30, 2022
Benefit Plans	BENEFIT PLANS NOTE 10(a) Pension and OPEB Plans - Net Periodic Benefit Costs - The components of net periodic benefit costs for sponsored defined benefit pension and OPEB plans for the three and nine months ended September 30 are included below (in millions). For IPL and WPL, amounts are for their plan participants covered under plans they sponsor, as well as amounts directly assigned to them related to certain participants in the Alliant Energy and Corporate Services sponsored plans. Defined Benefit Pension Plans OPEB Plans Three Months Nine Months Three Months Nine Months Alliant Energy 2022 2021 2022 2021 2022 2021 2022 2021 Service cost $3 $2 $7 $8 $— $1 $2 $3 Interest cost 9 9 27 26 1 1 4 3 Expected return on plan assets (18) (17) (52) (51) — (1) (3) (3) Amortization of prior service credit — (1) — (1) — — — — Amortization of actuarial loss 8 10 24 29 1 1 2 3 $2 $3 $6 $11 $2 $2 $5 $6 Defined Benefit Pension Plans OPEB Plans Three Months Nine Months Three Months Nine Months IPL 2022 2021 2022 2021 2022 2021 2022 2021 Service cost $1 $1 $4 $5 $— $— $1 $1 Interest cost 4 4 12 12 1 1 2 2 Expected return on plan assets (7) (8) (23) (24) (1) (1) (3) (3) Amortization of actuarial loss 3 5 10 13 — — — 1 $1 $2 $3 $6 $— $— $— $1 Defined Benefit Pension Plans OPEB Plans Three Months Nine Months Three Months Nine Months WPL 2022 2021 2022 2021 2022 2021 2022 2021 Service cost $— $1 $2 $3 $— $1 $— $1 Interest cost 4 3 12 11 1 — 2 1 Expected return on plan assets (7) (8) (23) (23) — — — — Amortization of actuarial loss 4 5 12 14 — 1 1 2 $1 $1 $3 $5 $1 $2 $3 $4 NOTE 10(b) Equity-based Compensation Plans - A summary of compensation expense, including amounts allocated to IPL and WPL, and the related income tax benefits recognized for share-based compensation awards for the three and nine months ended September 30 was as follows (in millions): Alliant Energy IPL WPL Three Months Nine Months Three Months Nine Months Three Months Nine Months 2022 2021 2022 2021 2022 2021 2022 2021 2022 2021 2022 2021 Compensation expense $3 $4 $9 $9 $2 $2 $5 $5 $1 $2 $4 $4 Income tax benefits 1 1 3 3 — — 1 1 — — 1 1 As of September 30, 2022, Alliant Energy’s, IPL’s and WPL’s total unrecognized compensation cost related to share-based compensation awards was $8 million, $5 million and $3 million, respectively, which is expected to be recognized over a weighted average period of between 1 year and 2 years. For the nine months ended September 30, 2022, performance shares, performance restricted stock units and restricted stock units were granted to key employees under existing plans as follows. These shares and units will be paid out in shares of common stock, and are therefore accounted for as equity awards. Weighted Average Grants Grant Date Fair Value Performance shares 74,106 $54.45 Performance restricted stock units 84,670 57.01 Restricted stock units 77,122 56.88 As of September 30, 2022, 285,909 shares were included in the calculation of diluted EPS related to the nonvested equity awards.
IPL [Member]
Benefit Plans	BENEFIT PLANS NOTE 10(a) Pension and OPEB Plans - Net Periodic Benefit Costs - The components of net periodic benefit costs for sponsored defined benefit pension and OPEB plans for the three and nine months ended September 30 are included below (in millions). For IPL and WPL, amounts are for their plan participants covered under plans they sponsor, as well as amounts directly assigned to them related to certain participants in the Alliant Energy and Corporate Services sponsored plans. Defined Benefit Pension Plans OPEB Plans Three Months Nine Months Three Months Nine Months Alliant Energy 2022 2021 2022 2021 2022 2021 2022 2021 Service cost $3 $2 $7 $8 $— $1 $2 $3 Interest cost 9 9 27 26 1 1 4 3 Expected return on plan assets (18) (17) (52) (51) — (1) (3) (3) Amortization of prior service credit — (1) — (1) — — — — Amortization of actuarial loss 8 10 24 29 1 1 2 3 $2 $3 $6 $11 $2 $2 $5 $6 Defined Benefit Pension Plans OPEB Plans Three Months Nine Months Three Months Nine Months IPL 2022 2021 2022 2021 2022 2021 2022 2021 Service cost $1 $1 $4 $5 $— $— $1 $1 Interest cost 4 4 12 12 1 1 2 2 Expected return on plan assets (7) (8) (23) (24) (1) (1) (3) (3) Amortization of actuarial loss 3 5 10 13 — — — 1 $1 $2 $3 $6 $— $— $— $1 Defined Benefit Pension Plans OPEB Plans Three Months Nine Months Three Months Nine Months WPL 2022 2021 2022 2021 2022 2021 2022 2021 Service cost $— $1 $2 $3 $— $1 $— $1 Interest cost 4 3 12 11 1 — 2 1 Expected return on plan assets (7) (8) (23) (23) — — — — Amortization of actuarial loss 4 5 12 14 — 1 1 2 $1 $1 $3 $5 $1 $2 $3 $4 NOTE 10(b) Equity-based Compensation Plans - A summary of compensation expense, including amounts allocated to IPL and WPL, and the related income tax benefits recognized for share-based compensation awards for the three and nine months ended September 30 was as follows (in millions): Alliant Energy IPL WPL Three Months Nine Months Three Months Nine Months Three Months Nine Months 2022 2021 2022 2021 2022 2021 2022 2021 2022 2021 2022 2021 Compensation expense $3 $4 $9 $9 $2 $2 $5 $5 $1 $2 $4 $4 Income tax benefits 1 1 3 3 — — 1 1 — — 1 1 As of September 30, 2022, Alliant Energy’s, IPL’s and WPL’s total unrecognized compensation cost related to share-based compensation awards was $8 million, $5 million and $3 million, respectively, which is expected to be recognized over a weighted average period of between 1 year and 2 years. For the nine months ended September 30, 2022, performance shares, performance restricted stock units and restricted stock units were granted to key employees under existing plans as follows. These shares and units will be paid out in shares of common stock, and are therefore accounted for as equity awards. Weighted Average Grants Grant Date Fair Value Performance shares 74,106 $54.45 Performance restricted stock units 84,670 57.01 Restricted stock units 77,122 56.88 As of September 30, 2022, 285,909 shares were included in the calculation of diluted EPS related to the nonvested equity awards.
WPL [Member]
Benefit Plans	BENEFIT PLANS NOTE 10(a) Pension and OPEB Plans - Net Periodic Benefit Costs - The components of net periodic benefit costs for sponsored defined benefit pension and OPEB plans for the three and nine months ended September 30 are included below (in millions). For IPL and WPL, amounts are for their plan participants covered under plans they sponsor, as well as amounts directly assigned to them related to certain participants in the Alliant Energy and Corporate Services sponsored plans. Defined Benefit Pension Plans OPEB Plans Three Months Nine Months Three Months Nine Months Alliant Energy 2022 2021 2022 2021 2022 2021 2022 2021 Service cost $3 $2 $7 $8 $— $1 $2 $3 Interest cost 9 9 27 26 1 1 4 3 Expected return on plan assets (18) (17) (52) (51) — (1) (3) (3) Amortization of prior service credit — (1) — (1) — — — — Amortization of actuarial loss 8 10 24 29 1 1 2 3 $2 $3 $6 $11 $2 $2 $5 $6 Defined Benefit Pension Plans OPEB Plans Three Months Nine Months Three Months Nine Months IPL 2022 2021 2022 2021 2022 2021 2022 2021 Service cost $1 $1 $4 $5 $— $— $1 $1 Interest cost 4 4 12 12 1 1 2 2 Expected return on plan assets (7) (8) (23) (24) (1) (1) (3) (3) Amortization of actuarial loss 3 5 10 13 — — — 1 $1 $2 $3 $6 $— $— $— $1 Defined Benefit Pension Plans OPEB Plans Three Months Nine Months Three Months Nine Months WPL 2022 2021 2022 2021 2022 2021 2022 2021 Service cost $— $1 $2 $3 $— $1 $— $1 Interest cost 4 3 12 11 1 — 2 1 Expected return on plan assets (7) (8) (23) (23) — — — — Amortization of actuarial loss 4 5 12 14 — 1 1 2 $1 $1 $3 $5 $1 $2 $3 $4 NOTE 10(b) Equity-based Compensation Plans - A summary of compensation expense, including amounts allocated to IPL and WPL, and the related income tax benefits recognized for share-based compensation awards for the three and nine months ended September 30 was as follows (in millions): Alliant Energy IPL WPL Three Months Nine Months Three Months Nine Months Three Months Nine Months 2022 2021 2022 2021 2022 2021 2022 2021 2022 2021 2022 2021 Compensation expense $3 $4 $9 $9 $2 $2 $5 $5 $1 $2 $4 $4 Income tax benefits 1 1 3 3 — — 1 1 — — 1 1 As of September 30, 2022, Alliant Energy’s, IPL’s and WPL’s total unrecognized compensation cost related to share-based compensation awards was $8 million, $5 million and $3 million, respectively, which is expected to be recognized over a weighted average period of between 1 year and 2 years. For the nine months ended September 30, 2022, performance shares, performance restricted stock units and restricted stock units were granted to key employees under existing plans as follows. These shares and units will be paid out in shares of common stock, and are therefore accounted for as equity awards. Weighted Average Grants Grant Date Fair Value Performance shares 74,106 $54.45 Performance restricted stock units 84,670 57.01 Restricted stock units 77,122 56.88 As of September 30, 2022, 285,909 shares were included in the calculation of diluted EPS related to the nonvested equity awards.

Derivative Instruments

Derivative Instruments	9 Months Ended
	Sep. 30, 2022
Derivative Instruments [Line Items]
Derivative Instruments	DERIVATIVE INSTRUMENTS Commodity Derivatives - Notional Amounts - As of September 30, 2022, gross notional amounts and settlement/delivery years related to outstanding swap contracts, option contracts, physical forward contracts and FTRs that were accounted for as commodity derivative instruments were as follows (units in thousands): Electricity FTRs Natural Gas Coal Diesel Fuel MWhs Years MWhs Years Dths Years Tons Years Gallons Years Alliant Energy 1,379 2022-2024 14,454 2022-2023 249,508 2022-2032 1,566 2022-2023 756 2022 IPL 768 2022-2024 6,165 2022-2023 135,193 2022-2030 669 2022-2023 — — WPL 611 2022-2023 8,289 2022-2023 114,315 2022-2032 897 2022-2023 756 2022 Financial Statement Presentation - Derivative instruments are recorded at fair value each reporting date on the balance sheets as assets or liabilities as follows (in millions): Alliant Energy IPL WPL September 30, December 31, September 30, December 31, September 30, December 31, Current derivative assets $200 $113 $117 $48 $83 $65 Non-current derivative assets 160 63 85 36 75 27 Current derivative liabilities 71 8 54 4 17 4 Non-current derivative liabilities 27 1 12 — 15 1 During the nine months ended September 30, 2022, Alliant Energy’s, IPL’s and WPL’s derivative assets increased primarily due to the annual FTR auction operated by MISO and as a result of higher natural gas prices. Alliant Energy’s, IPL’s and WPL’s derivative liabilities increased primarily due to new natural gas contracts entered into in the second quarter of 2022. Based on IPL’s and WPL’s cost recovery mechanisms, the changes in the fair value of derivative liabilities/assets resulted in comparable changes to regulatory assets/liabilities on the balance sheets. Credit Risk-related Contingent Features - Various agreements contain credit risk-related contingent features, including requirements to maintain certain credit ratings and/or limitations on liability positions under the agreements based on credit ratings. Certain of these agreements with credit risk-related contingency features are accounted for as derivative instruments. In the event of a material change in creditworthiness or if liability positions exceed certain contractual limits, credit support may need to be provided up to the amount of exposure under the contracts, or the contracts may need to be unwound and underlying liability positions paid. At September 30, 2022 and December 31, 2021, the aggregate fair value of all derivative instruments with credit risk-related contingent features in a net liability position was not materially different than amounts that would be required to be posted as credit support to counterparties by Alliant Energy, IPL or WPL if the most restrictive credit risk-related contingent features for derivative agreements in a net liability position were triggered. Balance Sheet Offsetting - The fair value amounts of derivative instruments subject to a master netting arrangement are not netted by counterparty on the balance sheets. However, if the fair value amounts of derivative instruments by counterparty were netted, derivative assets and derivative liabilities related to commodity contracts would have been presented on the balance sheets as follows (in millions): Alliant Energy IPL WPL Gross Gross Gross (as reported) Net (as reported) Net (as reported) Net September 30, 2022 Derivative assets $360 $308 $202 $165 $158 $143 Derivative liabilities 98 46 66 29 32 17 December 31, 2021 Derivative assets 176 171 84 83 92 88 Derivative liabilities 9 4 4 3 5 1 Fair value amounts recognized for the right to reclaim cash collateral (receivable) or the obligation to return cash collateral (payable) are not offset against fair value amounts recognized for derivative instruments executed with the same counterparty under the same master netting arrangement.
IPL [Member]
Derivative Instruments [Line Items]
Derivative Instruments	DERIVATIVE INSTRUMENTS Commodity Derivatives - Notional Amounts - As of September 30, 2022, gross notional amounts and settlement/delivery years related to outstanding swap contracts, option contracts, physical forward contracts and FTRs that were accounted for as commodity derivative instruments were as follows (units in thousands): Electricity FTRs Natural Gas Coal Diesel Fuel MWhs Years MWhs Years Dths Years Tons Years Gallons Years Alliant Energy 1,379 2022-2024 14,454 2022-2023 249,508 2022-2032 1,566 2022-2023 756 2022 IPL 768 2022-2024 6,165 2022-2023 135,193 2022-2030 669 2022-2023 — — WPL 611 2022-2023 8,289 2022-2023 114,315 2022-2032 897 2022-2023 756 2022 Financial Statement Presentation - Derivative instruments are recorded at fair value each reporting date on the balance sheets as assets or liabilities as follows (in millions): Alliant Energy IPL WPL September 30, December 31, September 30, December 31, September 30, December 31, Current derivative assets $200 $113 $117 $48 $83 $65 Non-current derivative assets 160 63 85 36 75 27 Current derivative liabilities 71 8 54 4 17 4 Non-current derivative liabilities 27 1 12 — 15 1 During the nine months ended September 30, 2022, Alliant Energy’s, IPL’s and WPL’s derivative assets increased primarily due to the annual FTR auction operated by MISO and as a result of higher natural gas prices. Alliant Energy’s, IPL’s and WPL’s derivative liabilities increased primarily due to new natural gas contracts entered into in the second quarter of 2022. Based on IPL’s and WPL’s cost recovery mechanisms, the changes in the fair value of derivative liabilities/assets resulted in comparable changes to regulatory assets/liabilities on the balance sheets. Credit Risk-related Contingent Features - Various agreements contain credit risk-related contingent features, including requirements to maintain certain credit ratings and/or limitations on liability positions under the agreements based on credit ratings. Certain of these agreements with credit risk-related contingency features are accounted for as derivative instruments. In the event of a material change in creditworthiness or if liability positions exceed certain contractual limits, credit support may need to be provided up to the amount of exposure under the contracts, or the contracts may need to be unwound and underlying liability positions paid. At September 30, 2022 and December 31, 2021, the aggregate fair value of all derivative instruments with credit risk-related contingent features in a net liability position was not materially different than amounts that would be required to be posted as credit support to counterparties by Alliant Energy, IPL or WPL if the most restrictive credit risk-related contingent features for derivative agreements in a net liability position were triggered. Balance Sheet Offsetting - The fair value amounts of derivative instruments subject to a master netting arrangement are not netted by counterparty on the balance sheets. However, if the fair value amounts of derivative instruments by counterparty were netted, derivative assets and derivative liabilities related to commodity contracts would have been presented on the balance sheets as follows (in millions): Alliant Energy IPL WPL Gross Gross Gross (as reported) Net (as reported) Net (as reported) Net September 30, 2022 Derivative assets $360 $308 $202 $165 $158 $143 Derivative liabilities 98 46 66 29 32 17 December 31, 2021 Derivative assets 176 171 84 83 92 88 Derivative liabilities 9 4 4 3 5 1 Fair value amounts recognized for the right to reclaim cash collateral (receivable) or the obligation to return cash collateral (payable) are not offset against fair value amounts recognized for derivative instruments executed with the same counterparty under the same master netting arrangement.
WPL [Member]
Derivative Instruments [Line Items]
Derivative Instruments	DERIVATIVE INSTRUMENTS Commodity Derivatives - Notional Amounts - As of September 30, 2022, gross notional amounts and settlement/delivery years related to outstanding swap contracts, option contracts, physical forward contracts and FTRs that were accounted for as commodity derivative instruments were as follows (units in thousands): Electricity FTRs Natural Gas Coal Diesel Fuel MWhs Years MWhs Years Dths Years Tons Years Gallons Years Alliant Energy 1,379 2022-2024 14,454 2022-2023 249,508 2022-2032 1,566 2022-2023 756 2022 IPL 768 2022-2024 6,165 2022-2023 135,193 2022-2030 669 2022-2023 — — WPL 611 2022-2023 8,289 2022-2023 114,315 2022-2032 897 2022-2023 756 2022 Financial Statement Presentation - Derivative instruments are recorded at fair value each reporting date on the balance sheets as assets or liabilities as follows (in millions): Alliant Energy IPL WPL September 30, December 31, September 30, December 31, September 30, December 31, Current derivative assets $200 $113 $117 $48 $83 $65 Non-current derivative assets 160 63 85 36 75 27 Current derivative liabilities 71 8 54 4 17 4 Non-current derivative liabilities 27 1 12 — 15 1 During the nine months ended September 30, 2022, Alliant Energy’s, IPL’s and WPL’s derivative assets increased primarily due to the annual FTR auction operated by MISO and as a result of higher natural gas prices. Alliant Energy’s, IPL’s and WPL’s derivative liabilities increased primarily due to new natural gas contracts entered into in the second quarter of 2022. Based on IPL’s and WPL’s cost recovery mechanisms, the changes in the fair value of derivative liabilities/assets resulted in comparable changes to regulatory assets/liabilities on the balance sheets. Credit Risk-related Contingent Features - Various agreements contain credit risk-related contingent features, including requirements to maintain certain credit ratings and/or limitations on liability positions under the agreements based on credit ratings. Certain of these agreements with credit risk-related contingency features are accounted for as derivative instruments. In the event of a material change in creditworthiness or if liability positions exceed certain contractual limits, credit support may need to be provided up to the amount of exposure under the contracts, or the contracts may need to be unwound and underlying liability positions paid. At September 30, 2022 and December 31, 2021, the aggregate fair value of all derivative instruments with credit risk-related contingent features in a net liability position was not materially different than amounts that would be required to be posted as credit support to counterparties by Alliant Energy, IPL or WPL if the most restrictive credit risk-related contingent features for derivative agreements in a net liability position were triggered. Balance Sheet Offsetting - The fair value amounts of derivative instruments subject to a master netting arrangement are not netted by counterparty on the balance sheets. However, if the fair value amounts of derivative instruments by counterparty were netted, derivative assets and derivative liabilities related to commodity contracts would have been presented on the balance sheets as follows (in millions): Alliant Energy IPL WPL Gross Gross Gross (as reported) Net (as reported) Net (as reported) Net September 30, 2022 Derivative assets $360 $308 $202 $165 $158 $143 Derivative liabilities 98 46 66 29 32 17 December 31, 2021 Derivative assets 176 171 84 83 92 88 Derivative liabilities 9 4 4 3 5 1 Fair value amounts recognized for the right to reclaim cash collateral (receivable) or the obligation to return cash collateral (payable) are not offset against fair value amounts recognized for derivative instruments executed with the same counterparty under the same master netting arrangement.

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2022
Fair Value Measurements	FAIR VALUE MEASUREMENTS Fair Value of Financial Instruments - The carrying amounts of current assets and current liabilities approximate fair value because of the short maturity of such financial instruments. Carrying amounts and related estimated fair values of other financial instruments were as follows (in millions): Alliant Energy September 30, 2022 December 31, 2021 Fair Value Fair Value Carrying Level Level Level Carrying Level Level Level Amount 1 2 3 Total Amount 1 2 3 Total Assets: Money market fund investments $334 $334 $— $— $334 $32 $32 $— $— $32 Derivatives 360 — 295 65 360 176 — 146 30 176 Deferred proceeds 248 — — 248 248 214 — — 214 214 Liabilities: Derivatives 98 — 78 20 98 9 — 8 1 9 Long-term debt (incl. current maturities) 8,228 — 7,473 1 7,474 7,368 — 8,329 1 8,330 IPL September 30, 2022 December 31, 2021 Fair Value Fair Value Carrying Level Level Level Carrying Level Level Level Amount 1 2 3 Total Amount 1 2 3 Total Assets: Money market fund investments $39 $39 $— $— $39 $32 $32 $— $— $32 Derivatives 202 — 150 52 202 84 — 65 19 84 Deferred proceeds 248 — — 248 248 214 — — 214 214 Liabilities: Derivatives 66 — 47 19 66 4 — 3 1 4 Long-term debt 3,645 — 3,228 — 3,228 3,643 — 4,124 — 4,124 WPL September 30, 2022 December 31, 2021 Fair Value Fair Value Carrying Level Level Level Carrying Level Level Level Amount 1 2 3 Total Amount 1 2 3 Total Assets: Money market fund investments $295 $295 $— $— $295 $— $— $— $— $— Derivatives 158 — 145 13 158 92 — 81 11 92 Liabilities: Derivatives 32 — 31 1 32 5 — 5 — 5 Long-term debt (incl. current maturities) 3,019 — 2,778 — 2,778 2,429 — 2,862 — 2,862 Information for fair value measurements using significant unobservable inputs (Level 3 inputs) was as follows (in millions): Alliant Energy Commodity Contract Derivative Assets and (Liabilities), net Deferred Proceeds Three Months Ended September 30 2022 2021 2022 2021 Beginning balance, July 1 $72 $39 $244 $154 Total net gains (losses) included in changes in net assets (realized/unrealized) (1) 5 — — Transfers out of Level 3 — (8) — — Settlements (a) (26) (7) 4 10 Ending balance, September 30 $45 $29 $248 $164 The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30 ($1) $5 $— $— Alliant Energy Commodity Contract Derivative Assets and (Liabilities), net Deferred Proceeds Nine Months Ended September 30 2022 2021 2022 2021 Beginning balance, January 1 $29 $29 $214 $188 Total net gains (losses) included in changes in net assets (realized/unrealized) (17) 6 — — Transfers out of Level 3 — (8) — — Purchases 79 21 — — Settlements (a) (46) (19) 34 (24) Ending balance, September 30 $45 $29 $248 $164 The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30 ($17) $6 $— $— IPL Commodity Contract Derivative Assets and (Liabilities), net Deferred Proceeds Three Months Ended September 30 2022 2021 2022 2021 Beginning balance, July 1 $58 $30 $244 $154 Total net gains (losses) included in changes in net assets (realized/unrealized) (6) 2 — — Transfers out of Level 3 — (8) — — Settlements (a) (19) (5) 4 10 Ending balance, September 30 $33 $19 $248 $164 The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30 ($6) $2 $— $— IPL Commodity Contract Derivative Assets and (Liabilities), net Deferred Proceeds Nine Months Ended September 30 2022 2021 2022 2021 Beginning balance, January 1 $18 $26 $214 $188 Total net losses included in changes in net assets (realized/unrealized) (13) — — — Transfers out of Level 3 — (8) — — Purchases 58 16 — — Settlements (a) (30) (15) 34 (24) Ending balance, September 30 $33 $19 $248 $164 The amount of total net losses for the period included in changes in net assets attributable to the change in unrealized losses relating to assets and liabilities held at September 30 ($14) $— $— $— WPL Commodity Contract Derivative Assets and (Liabilities), net Three Months Ended September 30 2022 2021 Beginning balance, July 1 $14 $9 Total net gains included in changes in net assets (realized/unrealized) 5 3 Settlements (7) (2) Ending balance, September 30 $12 $10 The amount of total net gains for the period included in changes in net assets attributable to the change in unrealized gains relating to assets and liabilities held at September 30 $5 $3 WPL Commodity Contract Derivative Assets and (Liabilities), net Nine Months Ended September 30 2022 2021 Beginning balance, January 1 $11 $3 Total net gains (losses) included in changes in net assets (realized/unrealized) (4) 6 Purchases 21 5 Settlements (16) (4) Ending balance, September 30 $12 $10 The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30 ($3) $6 (a) Settlements related to deferred proceeds are due to the change in the carrying amount of receivables sold less the allowance for expected credit losses associated with the receivables sold and cash amounts received from the receivables sold. Commodity Contracts - The fair value of FTR and natural gas commodity contracts categorized as Level 3 was recognized as net derivative assets (liabilities) as follows (in millions): Alliant Energy IPL WPL Excluding FTRs FTRs Excluding FTRs FTRs Excluding FTRs FTRs September 30, 2022 ($14) $59 ($15) $48 $1 $11 December 31, 2021 9 20 8 10 1 10
IPL [Member]
Fair Value Measurements	FAIR VALUE MEASUREMENTS Fair Value of Financial Instruments - The carrying amounts of current assets and current liabilities approximate fair value because of the short maturity of such financial instruments. Carrying amounts and related estimated fair values of other financial instruments were as follows (in millions): Alliant Energy September 30, 2022 December 31, 2021 Fair Value Fair Value Carrying Level Level Level Carrying Level Level Level Amount 1 2 3 Total Amount 1 2 3 Total Assets: Money market fund investments $334 $334 $— $— $334 $32 $32 $— $— $32 Derivatives 360 — 295 65 360 176 — 146 30 176 Deferred proceeds 248 — — 248 248 214 — — 214 214 Liabilities: Derivatives 98 — 78 20 98 9 — 8 1 9 Long-term debt (incl. current maturities) 8,228 — 7,473 1 7,474 7,368 — 8,329 1 8,330 IPL September 30, 2022 December 31, 2021 Fair Value Fair Value Carrying Level Level Level Carrying Level Level Level Amount 1 2 3 Total Amount 1 2 3 Total Assets: Money market fund investments $39 $39 $— $— $39 $32 $32 $— $— $32 Derivatives 202 — 150 52 202 84 — 65 19 84 Deferred proceeds 248 — — 248 248 214 — — 214 214 Liabilities: Derivatives 66 — 47 19 66 4 — 3 1 4 Long-term debt 3,645 — 3,228 — 3,228 3,643 — 4,124 — 4,124 WPL September 30, 2022 December 31, 2021 Fair Value Fair Value Carrying Level Level Level Carrying Level Level Level Amount 1 2 3 Total Amount 1 2 3 Total Assets: Money market fund investments $295 $295 $— $— $295 $— $— $— $— $— Derivatives 158 — 145 13 158 92 — 81 11 92 Liabilities: Derivatives 32 — 31 1 32 5 — 5 — 5 Long-term debt (incl. current maturities) 3,019 — 2,778 — 2,778 2,429 — 2,862 — 2,862 Information for fair value measurements using significant unobservable inputs (Level 3 inputs) was as follows (in millions): Alliant Energy Commodity Contract Derivative Assets and (Liabilities), net Deferred Proceeds Three Months Ended September 30 2022 2021 2022 2021 Beginning balance, July 1 $72 $39 $244 $154 Total net gains (losses) included in changes in net assets (realized/unrealized) (1) 5 — — Transfers out of Level 3 — (8) — — Settlements (a) (26) (7) 4 10 Ending balance, September 30 $45 $29 $248 $164 The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30 ($1) $5 $— $— Alliant Energy Commodity Contract Derivative Assets and (Liabilities), net Deferred Proceeds Nine Months Ended September 30 2022 2021 2022 2021 Beginning balance, January 1 $29 $29 $214 $188 Total net gains (losses) included in changes in net assets (realized/unrealized) (17) 6 — — Transfers out of Level 3 — (8) — — Purchases 79 21 — — Settlements (a) (46) (19) 34 (24) Ending balance, September 30 $45 $29 $248 $164 The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30 ($17) $6 $— $— IPL Commodity Contract Derivative Assets and (Liabilities), net Deferred Proceeds Three Months Ended September 30 2022 2021 2022 2021 Beginning balance, July 1 $58 $30 $244 $154 Total net gains (losses) included in changes in net assets (realized/unrealized) (6) 2 — — Transfers out of Level 3 — (8) — — Settlements (a) (19) (5) 4 10 Ending balance, September 30 $33 $19 $248 $164 The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30 ($6) $2 $— $— IPL Commodity Contract Derivative Assets and (Liabilities), net Deferred Proceeds Nine Months Ended September 30 2022 2021 2022 2021 Beginning balance, January 1 $18 $26 $214 $188 Total net losses included in changes in net assets (realized/unrealized) (13) — — — Transfers out of Level 3 — (8) — — Purchases 58 16 — — Settlements (a) (30) (15) 34 (24) Ending balance, September 30 $33 $19 $248 $164 The amount of total net losses for the period included in changes in net assets attributable to the change in unrealized losses relating to assets and liabilities held at September 30 ($14) $— $— $— WPL Commodity Contract Derivative Assets and (Liabilities), net Three Months Ended September 30 2022 2021 Beginning balance, July 1 $14 $9 Total net gains included in changes in net assets (realized/unrealized) 5 3 Settlements (7) (2) Ending balance, September 30 $12 $10 The amount of total net gains for the period included in changes in net assets attributable to the change in unrealized gains relating to assets and liabilities held at September 30 $5 $3 WPL Commodity Contract Derivative Assets and (Liabilities), net Nine Months Ended September 30 2022 2021 Beginning balance, January 1 $11 $3 Total net gains (losses) included in changes in net assets (realized/unrealized) (4) 6 Purchases 21 5 Settlements (16) (4) Ending balance, September 30 $12 $10 The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30 ($3) $6 (a) Settlements related to deferred proceeds are due to the change in the carrying amount of receivables sold less the allowance for expected credit losses associated with the receivables sold and cash amounts received from the receivables sold. Commodity Contracts - The fair value of FTR and natural gas commodity contracts categorized as Level 3 was recognized as net derivative assets (liabilities) as follows (in millions): Alliant Energy IPL WPL Excluding FTRs FTRs Excluding FTRs FTRs Excluding FTRs FTRs September 30, 2022 ($14) $59 ($15) $48 $1 $11 December 31, 2021 9 20 8 10 1 10
WPL [Member]
Fair Value Measurements	FAIR VALUE MEASUREMENTS Fair Value of Financial Instruments - The carrying amounts of current assets and current liabilities approximate fair value because of the short maturity of such financial instruments. Carrying amounts and related estimated fair values of other financial instruments were as follows (in millions): Alliant Energy September 30, 2022 December 31, 2021 Fair Value Fair Value Carrying Level Level Level Carrying Level Level Level Amount 1 2 3 Total Amount 1 2 3 Total Assets: Money market fund investments $334 $334 $— $— $334 $32 $32 $— $— $32 Derivatives 360 — 295 65 360 176 — 146 30 176 Deferred proceeds 248 — — 248 248 214 — — 214 214 Liabilities: Derivatives 98 — 78 20 98 9 — 8 1 9 Long-term debt (incl. current maturities) 8,228 — 7,473 1 7,474 7,368 — 8,329 1 8,330 IPL September 30, 2022 December 31, 2021 Fair Value Fair Value Carrying Level Level Level Carrying Level Level Level Amount 1 2 3 Total Amount 1 2 3 Total Assets: Money market fund investments $39 $39 $— $— $39 $32 $32 $— $— $32 Derivatives 202 — 150 52 202 84 — 65 19 84 Deferred proceeds 248 — — 248 248 214 — — 214 214 Liabilities: Derivatives 66 — 47 19 66 4 — 3 1 4 Long-term debt 3,645 — 3,228 — 3,228 3,643 — 4,124 — 4,124 WPL September 30, 2022 December 31, 2021 Fair Value Fair Value Carrying Level Level Level Carrying Level Level Level Amount 1 2 3 Total Amount 1 2 3 Total Assets: Money market fund investments $295 $295 $— $— $295 $— $— $— $— $— Derivatives 158 — 145 13 158 92 — 81 11 92 Liabilities: Derivatives 32 — 31 1 32 5 — 5 — 5 Long-term debt (incl. current maturities) 3,019 — 2,778 — 2,778 2,429 — 2,862 — 2,862 Information for fair value measurements using significant unobservable inputs (Level 3 inputs) was as follows (in millions): Alliant Energy Commodity Contract Derivative Assets and (Liabilities), net Deferred Proceeds Three Months Ended September 30 2022 2021 2022 2021 Beginning balance, July 1 $72 $39 $244 $154 Total net gains (losses) included in changes in net assets (realized/unrealized) (1) 5 — — Transfers out of Level 3 — (8) — — Settlements (a) (26) (7) 4 10 Ending balance, September 30 $45 $29 $248 $164 The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30 ($1) $5 $— $— Alliant Energy Commodity Contract Derivative Assets and (Liabilities), net Deferred Proceeds Nine Months Ended September 30 2022 2021 2022 2021 Beginning balance, January 1 $29 $29 $214 $188 Total net gains (losses) included in changes in net assets (realized/unrealized) (17) 6 — — Transfers out of Level 3 — (8) — — Purchases 79 21 — — Settlements (a) (46) (19) 34 (24) Ending balance, September 30 $45 $29 $248 $164 The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30 ($17) $6 $— $— IPL Commodity Contract Derivative Assets and (Liabilities), net Deferred Proceeds Three Months Ended September 30 2022 2021 2022 2021 Beginning balance, July 1 $58 $30 $244 $154 Total net gains (losses) included in changes in net assets (realized/unrealized) (6) 2 — — Transfers out of Level 3 — (8) — — Settlements (a) (19) (5) 4 10 Ending balance, September 30 $33 $19 $248 $164 The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30 ($6) $2 $— $— IPL Commodity Contract Derivative Assets and (Liabilities), net Deferred Proceeds Nine Months Ended September 30 2022 2021 2022 2021 Beginning balance, January 1 $18 $26 $214 $188 Total net losses included in changes in net assets (realized/unrealized) (13) — — — Transfers out of Level 3 — (8) — — Purchases 58 16 — — Settlements (a) (30) (15) 34 (24) Ending balance, September 30 $33 $19 $248 $164 The amount of total net losses for the period included in changes in net assets attributable to the change in unrealized losses relating to assets and liabilities held at September 30 ($14) $— $— $— WPL Commodity Contract Derivative Assets and (Liabilities), net Three Months Ended September 30 2022 2021 Beginning balance, July 1 $14 $9 Total net gains included in changes in net assets (realized/unrealized) 5 3 Settlements (7) (2) Ending balance, September 30 $12 $10 The amount of total net gains for the period included in changes in net assets attributable to the change in unrealized gains relating to assets and liabilities held at September 30 $5 $3 WPL Commodity Contract Derivative Assets and (Liabilities), net Nine Months Ended September 30 2022 2021 Beginning balance, January 1 $11 $3 Total net gains (losses) included in changes in net assets (realized/unrealized) (4) 6 Purchases 21 5 Settlements (16) (4) Ending balance, September 30 $12 $10 The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30 ($3) $6 (a) Settlements related to deferred proceeds are due to the change in the carrying amount of receivables sold less the allowance for expected credit losses associated with the receivables sold and cash amounts received from the receivables sold. Commodity Contracts - The fair value of FTR and natural gas commodity contracts categorized as Level 3 was recognized as net derivative assets (liabilities) as follows (in millions): Alliant Energy IPL WPL Excluding FTRs FTRs Excluding FTRs FTRs Excluding FTRs FTRs September 30, 2022 ($14) $59 ($15) $48 $1 $11 December 31, 2021 9 20 8 10 1 10

Commitments And Contingencies

Commitments And Contingencies	9 Months Ended
	Sep. 30, 2022
Commitments and Contingencies Disclosure	COMMITMENTS AND CONTINGENCIES NOTE 13(a) Capital Purchase Commitments - Various contractual obligations contain minimum future commitments related to capital expenditures for certain construction projects, including WPL’s expansion of solar generation. At September 30, 2022, Alliant Energy’s and WPL’s minimum future commitments for these projects were $208 million and $206 million, respectively. NOTE 13(b) Other Purchase Commitments - Various commodity supply, transportation and storage contracts help meet obligations to provide electricity and natural gas to utility customers. In addition, there are various purchase commitments associated with other goods and services. At September 30, 2022, related minimum future commitments were as follows (in millions): Alliant Energy IPL WPL Natural gas $1,608 $742 $866 Coal 197 95 102 Other (a) 126 57 28 $1,931 $894 $996 (a) Includes individual commitments incurred during the normal course of business that exceeded $1 million at September 30, 2022. NOTE 13(c) Guarantees and Indemnifications - Whiting Petroleum - Whiting Petroleum is an independent oil and gas company. In 2004, Alliant Energy sold its remaining interest in Whiting Petroleum. Alliant Energy Resources, LLC, as the successor to a predecessor entity that owned Whiting Petroleum, and a wholly-owned subsidiary of AEF, continues to guarantee the partnership obligations of an affiliate of Whiting Petroleum under multiple general partnership agreements in the oil and gas industry. The guarantees do not include a maximum limit. Based on information made available to Alliant Energy by Whiting Petroleum, the Whiting Petroleum affiliate holds an approximate 6% share in the partnerships, and currently known obligations include costs associated with the future abandonment of certain facilities owned by the partnerships. The general partnerships were formed under California law, and Alliant Energy Resources, LLC may need to perform under the guarantees if the affiliate of Whiting Petroleum is unable to meet its partnership obligations. As of September 30, 2022, the currently known partnership obligations for the abandonment obligations are estimated at $58 million, which represents Alliant Energy’s currently estimated maximum exposure under the guarantees. Alliant Energy estimates its expected loss to be a portion of the $58 million of known partnership abandonment obligations of the Whiting Petroleum affiliate and the other partners. Alliant Energy is not aware of any material liabilities related to these guarantees that it is probable that it will be obligated to pay; however, as of both September 30, 2022 and December 31, 2021, a liability of $5 million is recorded in “Other liabilities” on Alliant Energy’s balance sheets for expected credit losses related to the contingent obligations that are in the scope of these guarantees. Whiting Petroleum completed a business combination with Oasis Petroleum Inc. in July 2022. The combined operations are now known as Chord Energy Corporation. The business combination is not expected to affect the scope of the Whiting Petroleum affiliate’s obligations to Alliant Energy or Alliant Energy’s related guarantees. Non-utility Wind Farm in Oklahoma - In 2017, a wholly-owned subsidiary of AEF acquired a cash equity ownership interest in a non-utility wind farm located in Oklahoma. The wind farm provides electricity to a third party under a long-term PPA. Alliant Energy provided a parent guarantee of its subsidiary’s indemnification obligations under the related operating agreement and PPA. Alliant Energy’s obligations under the operating agreement were $59 million as of September 30, 2022 and will reduce annually until expiring in July 2047. Alliant Energy’s obligations under the PPA are subject to a maximum limit of $17 million and expire in December 2031, subject to potential extension. Alliant Energy is not aware of any material liabilities related to this guarantee that it is probable that it will be obligated to pay and therefore has not recognized any material liabilities related to this guarantee as of September 30, 2022 and December 31, 2021. NOTE 13(d) Environmental Matters - Manufactured Gas Plant (MGP) Sites - IPL and WPL have current or previous ownership interests in various sites that are previously associated with the production of gas for which IPL and WPL have, or may have in the future, liability for investigation, remediation and monitoring costs. IPL and WPL are working pursuant to the requirements of various federal and state agencies to investigate, mitigate, prevent and remediate, where necessary, the environmental impacts to property, including natural resources, at and around these former MGP sites in order to protect public health and the environment. At September 30, 2022, estimated future costs expected to be incurred for the investigation, remediation and monitoring of the MGP sites, as well as environmental liabilities recorded on the balance sheets for these sites, which are not discounted, were as follows (in millions). At September 30, 2022, such amounts for WPL were not material. Alliant Energy IPL Range of estimated future costs $9 - $25 $6 - $19 Current and non-current environmental liabilities $12 $8 IPL Consent Decree - In 2015, the U.S. District Court for the Northern District of Iowa approved a Consent Decree that IPL entered into with the EPA, the Sierra Club, the State of Iowa and Linn County in Iowa, thereby resolving potential Clean Air Act issues associated with emissions from IPL’s coal-fired generating facilities in Iowa. IPL has completed various requirements under the Consent Decree. IPL’s remaining requirements include fuel switching or retiring Prairie Creek Units 1 and 3 by December 31, 2025. Alliant Energy and IPL currently expect to recover material costs incurred by IPL related to compliance with the terms of the Consent Decree from IPL’s electric customers. Other Environmental Contingencies - In addition to the environmental liabilities discussed above, various environmental rules are monitored that may have a significant impact on future operations. Several of these environmental rules are subject to legal challenges, reconsideration and/or other uncertainties. Given uncertainties regarding the outcome, timing and compliance plans for these environmental matters, the complete financial impact of each of these rules is not able to be determined; however, future capital investments and/or modifications to EGUs and electric and gas distribution systems to comply with certain of these rules could be significant. Specific current, proposed or potential environmental matters include, among others: Effluent Limitation Guidelines, Coal Combustion Residuals Rule, and various legislation and EPA regulations to monitor and regulate the emission of greenhouse gases, including the Clean Air Act. NOTE 13(e) MISO Transmission Owner Return on Equity Complaints - A group of stakeholders, including MISO cooperative and municipal utilities, previously filed complaints with FERC requesting a reduction to the base return on equity authorized for MISO transmission owners, including ITC Midwest LLC and ATC. In 2019, FERC issued an order on the previously filed complaints and reduced the base return on equity authorized for the MISO transmission owners to 9.88% for November 12, 2013 through February 11, 2015, and subsequent to September 28, 2016. In 2020, FERC issued orders in response to various rehearing requests and increased the base return on equity authorized for the MISO transmission owners from 9.88% to 10.02% for November 12, 2013 through February 11, 2015, and subsequent to September 28, 2016. In August 2022, the U.S. Court of Appeals for the District of Columbia Circuit vacated FERC’s prior orders that established the base return on equity authorized for the MISO transmission owners and remanded the cases to FERC for further proceedings, which may result in additional changes to the base return on equity authorized for the MISO transmission owners. As a result of the August 2022 court decision, Alliant Energy recorded a $5 million reduction in “Equity income from unconsolidated investments” in its income statement for the three and nine months ended September 30, 2022 to reflect the anticipated reduction in the base return on equity authorized for the MISO transmission owners. Any further changes in FERC’s decisions may have an impact on Alliant Energy’s share of ATC’s future earnings and customer costs.
IPL [Member]
Commitments and Contingencies Disclosure	COMMITMENTS AND CONTINGENCIES NOTE 13(a) Capital Purchase Commitments - Various contractual obligations contain minimum future commitments related to capital expenditures for certain construction projects, including WPL’s expansion of solar generation. At September 30, 2022, Alliant Energy’s and WPL’s minimum future commitments for these projects were $208 million and $206 million, respectively. NOTE 13(b) Other Purchase Commitments - Various commodity supply, transportation and storage contracts help meet obligations to provide electricity and natural gas to utility customers. In addition, there are various purchase commitments associated with other goods and services. At September 30, 2022, related minimum future commitments were as follows (in millions): Alliant Energy IPL WPL Natural gas $1,608 $742 $866 Coal 197 95 102 Other (a) 126 57 28 $1,931 $894 $996 (a) Includes individual commitments incurred during the normal course of business that exceeded $1 million at September 30, 2022. NOTE 13(c) Guarantees and Indemnifications - Whiting Petroleum - Whiting Petroleum is an independent oil and gas company. In 2004, Alliant Energy sold its remaining interest in Whiting Petroleum. Alliant Energy Resources, LLC, as the successor to a predecessor entity that owned Whiting Petroleum, and a wholly-owned subsidiary of AEF, continues to guarantee the partnership obligations of an affiliate of Whiting Petroleum under multiple general partnership agreements in the oil and gas industry. The guarantees do not include a maximum limit. Based on information made available to Alliant Energy by Whiting Petroleum, the Whiting Petroleum affiliate holds an approximate 6% share in the partnerships, and currently known obligations include costs associated with the future abandonment of certain facilities owned by the partnerships. The general partnerships were formed under California law, and Alliant Energy Resources, LLC may need to perform under the guarantees if the affiliate of Whiting Petroleum is unable to meet its partnership obligations. As of September 30, 2022, the currently known partnership obligations for the abandonment obligations are estimated at $58 million, which represents Alliant Energy’s currently estimated maximum exposure under the guarantees. Alliant Energy estimates its expected loss to be a portion of the $58 million of known partnership abandonment obligations of the Whiting Petroleum affiliate and the other partners. Alliant Energy is not aware of any material liabilities related to these guarantees that it is probable that it will be obligated to pay; however, as of both September 30, 2022 and December 31, 2021, a liability of $5 million is recorded in “Other liabilities” on Alliant Energy’s balance sheets for expected credit losses related to the contingent obligations that are in the scope of these guarantees. Whiting Petroleum completed a business combination with Oasis Petroleum Inc. in July 2022. The combined operations are now known as Chord Energy Corporation. The business combination is not expected to affect the scope of the Whiting Petroleum affiliate’s obligations to Alliant Energy or Alliant Energy’s related guarantees. Non-utility Wind Farm in Oklahoma - In 2017, a wholly-owned subsidiary of AEF acquired a cash equity ownership interest in a non-utility wind farm located in Oklahoma. The wind farm provides electricity to a third party under a long-term PPA. Alliant Energy provided a parent guarantee of its subsidiary’s indemnification obligations under the related operating agreement and PPA. Alliant Energy’s obligations under the operating agreement were $59 million as of September 30, 2022 and will reduce annually until expiring in July 2047. Alliant Energy’s obligations under the PPA are subject to a maximum limit of $17 million and expire in December 2031, subject to potential extension. Alliant Energy is not aware of any material liabilities related to this guarantee that it is probable that it will be obligated to pay and therefore has not recognized any material liabilities related to this guarantee as of September 30, 2022 and December 31, 2021. NOTE 13(d) Environmental Matters - Manufactured Gas Plant (MGP) Sites - IPL and WPL have current or previous ownership interests in various sites that are previously associated with the production of gas for which IPL and WPL have, or may have in the future, liability for investigation, remediation and monitoring costs. IPL and WPL are working pursuant to the requirements of various federal and state agencies to investigate, mitigate, prevent and remediate, where necessary, the environmental impacts to property, including natural resources, at and around these former MGP sites in order to protect public health and the environment. At September 30, 2022, estimated future costs expected to be incurred for the investigation, remediation and monitoring of the MGP sites, as well as environmental liabilities recorded on the balance sheets for these sites, which are not discounted, were as follows (in millions). At September 30, 2022, such amounts for WPL were not material. Alliant Energy IPL Range of estimated future costs $9 - $25 $6 - $19 Current and non-current environmental liabilities $12 $8 IPL Consent Decree - In 2015, the U.S. District Court for the Northern District of Iowa approved a Consent Decree that IPL entered into with the EPA, the Sierra Club, the State of Iowa and Linn County in Iowa, thereby resolving potential Clean Air Act issues associated with emissions from IPL’s coal-fired generating facilities in Iowa. IPL has completed various requirements under the Consent Decree. IPL’s remaining requirements include fuel switching or retiring Prairie Creek Units 1 and 3 by December 31, 2025. Alliant Energy and IPL currently expect to recover material costs incurred by IPL related to compliance with the terms of the Consent Decree from IPL’s electric customers. Other Environmental Contingencies - In addition to the environmental liabilities discussed above, various environmental rules are monitored that may have a significant impact on future operations. Several of these environmental rules are subject to legal challenges, reconsideration and/or other uncertainties. Given uncertainties regarding the outcome, timing and compliance plans for these environmental matters, the complete financial impact of each of these rules is not able to be determined; however, future capital investments and/or modifications to EGUs and electric and gas distribution systems to comply with certain of these rules could be significant. Specific current, proposed or potential environmental matters include, among others: Effluent Limitation Guidelines, Coal Combustion Residuals Rule, and various legislation and EPA regulations to monitor and regulate the emission of greenhouse gases, including the Clean Air Act. NOTE 13(e) MISO Transmission Owner Return on Equity Complaints - A group of stakeholders, including MISO cooperative and municipal utilities, previously filed complaints with FERC requesting a reduction to the base return on equity authorized for MISO transmission owners, including ITC Midwest LLC and ATC. In 2019, FERC issued an order on the previously filed complaints and reduced the base return on equity authorized for the MISO transmission owners to 9.88% for November 12, 2013 through February 11, 2015, and subsequent to September 28, 2016. In 2020, FERC issued orders in response to various rehearing requests and increased the base return on equity authorized for the MISO transmission owners from 9.88% to 10.02% for November 12, 2013 through February 11, 2015, and subsequent to September 28, 2016. In August 2022, the U.S. Court of Appeals for the District of Columbia Circuit vacated FERC’s prior orders that established the base return on equity authorized for the MISO transmission owners and remanded the cases to FERC for further proceedings, which may result in additional changes to the base return on equity authorized for the MISO transmission owners. As a result of the August 2022 court decision, Alliant Energy recorded a $5 million reduction in “Equity income from unconsolidated investments” in its income statement for the three and nine months ended September 30, 2022 to reflect the anticipated reduction in the base return on equity authorized for the MISO transmission owners. Any further changes in FERC’s decisions may have an impact on Alliant Energy’s share of ATC’s future earnings and customer costs.
WPL [Member]
Commitments and Contingencies Disclosure	COMMITMENTS AND CONTINGENCIES NOTE 13(a) Capital Purchase Commitments - Various contractual obligations contain minimum future commitments related to capital expenditures for certain construction projects, including WPL’s expansion of solar generation. At September 30, 2022, Alliant Energy’s and WPL’s minimum future commitments for these projects were $208 million and $206 million, respectively. NOTE 13(b) Other Purchase Commitments - Various commodity supply, transportation and storage contracts help meet obligations to provide electricity and natural gas to utility customers. In addition, there are various purchase commitments associated with other goods and services. At September 30, 2022, related minimum future commitments were as follows (in millions): Alliant Energy IPL WPL Natural gas $1,608 $742 $866 Coal 197 95 102 Other (a) 126 57 28 $1,931 $894 $996 (a) Includes individual commitments incurred during the normal course of business that exceeded $1 million at September 30, 2022. NOTE 13(c) Guarantees and Indemnifications - Whiting Petroleum - Whiting Petroleum is an independent oil and gas company. In 2004, Alliant Energy sold its remaining interest in Whiting Petroleum. Alliant Energy Resources, LLC, as the successor to a predecessor entity that owned Whiting Petroleum, and a wholly-owned subsidiary of AEF, continues to guarantee the partnership obligations of an affiliate of Whiting Petroleum under multiple general partnership agreements in the oil and gas industry. The guarantees do not include a maximum limit. Based on information made available to Alliant Energy by Whiting Petroleum, the Whiting Petroleum affiliate holds an approximate 6% share in the partnerships, and currently known obligations include costs associated with the future abandonment of certain facilities owned by the partnerships. The general partnerships were formed under California law, and Alliant Energy Resources, LLC may need to perform under the guarantees if the affiliate of Whiting Petroleum is unable to meet its partnership obligations. As of September 30, 2022, the currently known partnership obligations for the abandonment obligations are estimated at $58 million, which represents Alliant Energy’s currently estimated maximum exposure under the guarantees. Alliant Energy estimates its expected loss to be a portion of the $58 million of known partnership abandonment obligations of the Whiting Petroleum affiliate and the other partners. Alliant Energy is not aware of any material liabilities related to these guarantees that it is probable that it will be obligated to pay; however, as of both September 30, 2022 and December 31, 2021, a liability of $5 million is recorded in “Other liabilities” on Alliant Energy’s balance sheets for expected credit losses related to the contingent obligations that are in the scope of these guarantees. Whiting Petroleum completed a business combination with Oasis Petroleum Inc. in July 2022. The combined operations are now known as Chord Energy Corporation. The business combination is not expected to affect the scope of the Whiting Petroleum affiliate’s obligations to Alliant Energy or Alliant Energy’s related guarantees. Non-utility Wind Farm in Oklahoma - In 2017, a wholly-owned subsidiary of AEF acquired a cash equity ownership interest in a non-utility wind farm located in Oklahoma. The wind farm provides electricity to a third party under a long-term PPA. Alliant Energy provided a parent guarantee of its subsidiary’s indemnification obligations under the related operating agreement and PPA. Alliant Energy’s obligations under the operating agreement were $59 million as of September 30, 2022 and will reduce annually until expiring in July 2047. Alliant Energy’s obligations under the PPA are subject to a maximum limit of $17 million and expire in December 2031, subject to potential extension. Alliant Energy is not aware of any material liabilities related to this guarantee that it is probable that it will be obligated to pay and therefore has not recognized any material liabilities related to this guarantee as of September 30, 2022 and December 31, 2021. NOTE 13(d) Environmental Matters - Manufactured Gas Plant (MGP) Sites - IPL and WPL have current or previous ownership interests in various sites that are previously associated with the production of gas for which IPL and WPL have, or may have in the future, liability for investigation, remediation and monitoring costs. IPL and WPL are working pursuant to the requirements of various federal and state agencies to investigate, mitigate, prevent and remediate, where necessary, the environmental impacts to property, including natural resources, at and around these former MGP sites in order to protect public health and the environment. At September 30, 2022, estimated future costs expected to be incurred for the investigation, remediation and monitoring of the MGP sites, as well as environmental liabilities recorded on the balance sheets for these sites, which are not discounted, were as follows (in millions). At September 30, 2022, such amounts for WPL were not material. Alliant Energy IPL Range of estimated future costs $9 - $25 $6 - $19 Current and non-current environmental liabilities $12 $8 IPL Consent Decree - In 2015, the U.S. District Court for the Northern District of Iowa approved a Consent Decree that IPL entered into with the EPA, the Sierra Club, the State of Iowa and Linn County in Iowa, thereby resolving potential Clean Air Act issues associated with emissions from IPL’s coal-fired generating facilities in Iowa. IPL has completed various requirements under the Consent Decree. IPL’s remaining requirements include fuel switching or retiring Prairie Creek Units 1 and 3 by December 31, 2025. Alliant Energy and IPL currently expect to recover material costs incurred by IPL related to compliance with the terms of the Consent Decree from IPL’s electric customers. Other Environmental Contingencies - In addition to the environmental liabilities discussed above, various environmental rules are monitored that may have a significant impact on future operations. Several of these environmental rules are subject to legal challenges, reconsideration and/or other uncertainties. Given uncertainties regarding the outcome, timing and compliance plans for these environmental matters, the complete financial impact of each of these rules is not able to be determined; however, future capital investments and/or modifications to EGUs and electric and gas distribution systems to comply with certain of these rules could be significant. Specific current, proposed or potential environmental matters include, among others: Effluent Limitation Guidelines, Coal Combustion Residuals Rule, and various legislation and EPA regulations to monitor and regulate the emission of greenhouse gases, including the Clean Air Act. NOTE 13(e) MISO Transmission Owner Return on Equity Complaints - A group of stakeholders, including MISO cooperative and municipal utilities, previously filed complaints with FERC requesting a reduction to the base return on equity authorized for MISO transmission owners, including ITC Midwest LLC and ATC. In 2019, FERC issued an order on the previously filed complaints and reduced the base return on equity authorized for the MISO transmission owners to 9.88% for November 12, 2013 through February 11, 2015, and subsequent to September 28, 2016. In 2020, FERC issued orders in response to various rehearing requests and increased the base return on equity authorized for the MISO transmission owners from 9.88% to 10.02% for November 12, 2013 through February 11, 2015, and subsequent to September 28, 2016. In August 2022, the U.S. Court of Appeals for the District of Columbia Circuit vacated FERC’s prior orders that established the base return on equity authorized for the MISO transmission owners and remanded the cases to FERC for further proceedings, which may result in additional changes to the base return on equity authorized for the MISO transmission owners. As a result of the August 2022 court decision, Alliant Energy recorded a $5 million reduction in “Equity income from unconsolidated investments” in its income statement for the three and nine months ended September 30, 2022 to reflect the anticipated reduction in the base return on equity authorized for the MISO transmission owners. Any further changes in FERC’s decisions may have an impact on Alliant Energy’s share of ATC’s future earnings and customer costs.

Segments Of Business

Segments Of Business	9 Months Ended
	Sep. 30, 2022
Segment Reporting Information [Line Items]
Segments Of Business	SEGMENTS OF BUSINESS Certain financial information relating to Alliant Energy’s, IPL’s and WPL’s business segments is as follows. Intersegment revenues were not material to their respective operations. Alliant Energy ATC Holdings, Alliant Utility Non-Utility, Energy Electric Gas Other Total Parent and Other Consolidated (in millions) Three Months Ended September 30, 2022 Revenues $1,039 $62 $11 $1,112 $23 $1,135 Operating income (loss) 304 (3) 1 302 7 309 Net income (loss) attributable to Alliant Energy common shareowners 245 (18) 227 Three Months Ended September 30, 2021 Revenues $939 $50 $13 $1,002 $22 $1,024 Operating income (loss) 290 (5) (5) 280 9 289 Net income attributable to Alliant Energy common shareowners 250 6 256 Alliant Energy ATC Holdings, Alliant Utility Non-Utility, Energy Electric Gas Other Total Parent and Other Consolidated (in millions) Nine Months Ended September 30, 2022 Revenues $2,624 $418 $35 $3,077 $70 $3,147 Operating income 680 62 4 746 23 769 Net income attributable to Alliant Energy common shareowners 574 5 579 Nine Months Ended September 30, 2021 Revenues $2,357 $289 $36 $2,682 $60 $2,742 Operating income (loss) 601 42 (4) 639 24 663 Net income attributable to Alliant Energy common shareowners 537 34 571 IPL Electric Gas Other Total (in millions) Three Months Ended September 30, 2022 Revenues $596 $33 $11 $640 Operating income (loss) 174 (3) — 171 Net income available for common stock 154 Three Months Ended September 30, 2021 Revenues $555 $31 $13 $599 Operating income (loss) 186 (3) (3) 180 Net income available for common stock 157 Nine Months Ended September 30, 2022 Revenues $1,438 $224 $34 $1,696 Operating income 353 33 3 389 Net income available for common stock 327 Nine Months Ended September 30, 2021 Revenues $1,343 $165 $35 $1,543 Operating income (loss) 365 30 (1) 394 Net income available for common stock 322 WPL Electric Gas Other Total (in millions) Three Months Ended September 30, 2022 Revenues $443 $29 $— $472 Operating income 130 — 1 131 Net income 91 Three Months Ended September 30, 2021 Revenues $384 $19 $— $403 Operating income (loss) 104 (2) (2) 100 Net income 93 Nine Months Ended September 30, 2022 Revenues $1,186 $194 $1 $1,381 Operating income 327 29 1 357 Net income 247 Nine Months Ended September 30, 2021 Revenues $1,014 $124 $1 $1,139 Operating income (loss) 236 12 (3) 245 Net income 215
IPL [Member]
Segment Reporting Information [Line Items]
Segments Of Business	SEGMENTS OF BUSINESS Certain financial information relating to Alliant Energy’s, IPL’s and WPL’s business segments is as follows. Intersegment revenues were not material to their respective operations. Alliant Energy ATC Holdings, Alliant Utility Non-Utility, Energy Electric Gas Other Total Parent and Other Consolidated (in millions) Three Months Ended September 30, 2022 Revenues $1,039 $62 $11 $1,112 $23 $1,135 Operating income (loss) 304 (3) 1 302 7 309 Net income (loss) attributable to Alliant Energy common shareowners 245 (18) 227 Three Months Ended September 30, 2021 Revenues $939 $50 $13 $1,002 $22 $1,024 Operating income (loss) 290 (5) (5) 280 9 289 Net income attributable to Alliant Energy common shareowners 250 6 256 Alliant Energy ATC Holdings, Alliant Utility Non-Utility, Energy Electric Gas Other Total Parent and Other Consolidated (in millions) Nine Months Ended September 30, 2022 Revenues $2,624 $418 $35 $3,077 $70 $3,147 Operating income 680 62 4 746 23 769 Net income attributable to Alliant Energy common shareowners 574 5 579 Nine Months Ended September 30, 2021 Revenues $2,357 $289 $36 $2,682 $60 $2,742 Operating income (loss) 601 42 (4) 639 24 663 Net income attributable to Alliant Energy common shareowners 537 34 571 IPL Electric Gas Other Total (in millions) Three Months Ended September 30, 2022 Revenues $596 $33 $11 $640 Operating income (loss) 174 (3) — 171 Net income available for common stock 154 Three Months Ended September 30, 2021 Revenues $555 $31 $13 $599 Operating income (loss) 186 (3) (3) 180 Net income available for common stock 157 Nine Months Ended September 30, 2022 Revenues $1,438 $224 $34 $1,696 Operating income 353 33 3 389 Net income available for common stock 327 Nine Months Ended September 30, 2021 Revenues $1,343 $165 $35 $1,543 Operating income (loss) 365 30 (1) 394 Net income available for common stock 322 WPL Electric Gas Other Total (in millions) Three Months Ended September 30, 2022 Revenues $443 $29 $— $472 Operating income 130 — 1 131 Net income 91 Three Months Ended September 30, 2021 Revenues $384 $19 $— $403 Operating income (loss) 104 (2) (2) 100 Net income 93 Nine Months Ended September 30, 2022 Revenues $1,186 $194 $1 $1,381 Operating income 327 29 1 357 Net income 247 Nine Months Ended September 30, 2021 Revenues $1,014 $124 $1 $1,139 Operating income (loss) 236 12 (3) 245 Net income 215
WPL [Member]
Segment Reporting Information [Line Items]
Segments Of Business	SEGMENTS OF BUSINESS Certain financial information relating to Alliant Energy’s, IPL’s and WPL’s business segments is as follows. Intersegment revenues were not material to their respective operations. Alliant Energy ATC Holdings, Alliant Utility Non-Utility, Energy Electric Gas Other Total Parent and Other Consolidated (in millions) Three Months Ended September 30, 2022 Revenues $1,039 $62 $11 $1,112 $23 $1,135 Operating income (loss) 304 (3) 1 302 7 309 Net income (loss) attributable to Alliant Energy common shareowners 245 (18) 227 Three Months Ended September 30, 2021 Revenues $939 $50 $13 $1,002 $22 $1,024 Operating income (loss) 290 (5) (5) 280 9 289 Net income attributable to Alliant Energy common shareowners 250 6 256 Alliant Energy ATC Holdings, Alliant Utility Non-Utility, Energy Electric Gas Other Total Parent and Other Consolidated (in millions) Nine Months Ended September 30, 2022 Revenues $2,624 $418 $35 $3,077 $70 $3,147 Operating income 680 62 4 746 23 769 Net income attributable to Alliant Energy common shareowners 574 5 579 Nine Months Ended September 30, 2021 Revenues $2,357 $289 $36 $2,682 $60 $2,742 Operating income (loss) 601 42 (4) 639 24 663 Net income attributable to Alliant Energy common shareowners 537 34 571 IPL Electric Gas Other Total (in millions) Three Months Ended September 30, 2022 Revenues $596 $33 $11 $640 Operating income (loss) 174 (3) — 171 Net income available for common stock 154 Three Months Ended September 30, 2021 Revenues $555 $31 $13 $599 Operating income (loss) 186 (3) (3) 180 Net income available for common stock 157 Nine Months Ended September 30, 2022 Revenues $1,438 $224 $34 $1,696 Operating income 353 33 3 389 Net income available for common stock 327 Nine Months Ended September 30, 2021 Revenues $1,343 $165 $35 $1,543 Operating income (loss) 365 30 (1) 394 Net income available for common stock 322 WPL Electric Gas Other Total (in millions) Three Months Ended September 30, 2022 Revenues $443 $29 $— $472 Operating income 130 — 1 131 Net income 91 Three Months Ended September 30, 2021 Revenues $384 $19 $— $403 Operating income (loss) 104 (2) (2) 100 Net income 93 Nine Months Ended September 30, 2022 Revenues $1,186 $194 $1 $1,381 Operating income 327 29 1 357 Net income 247 Nine Months Ended September 30, 2021 Revenues $1,014 $124 $1 $1,139 Operating income (loss) 236 12 (3) 245 Net income 215

Related Parties

Related Parties	9 Months Ended
	Sep. 30, 2022
Related Party Transactions [Line Items]
Related Parties	RELATED PARTIES Service Agreements - Pursuant to service agreements, IPL and WPL receive various administrative and general services from an affiliate, Corporate Services. These services are billed to IPL and WPL at cost based on expenses incurred by Corporate Services for the benefit of IPL and WPL, respectively. These costs consisted primarily of employee compensation and benefits, fees associated with various professional services, depreciation and amortization of property, plant and equipment, and a return on net assets. Corporate Services also acts as agent on behalf of IPL and WPL pursuant to the service agreements. As agent, Corporate Services enters into energy, capacity, ancillary services, and transmission sale and purchase transactions within MISO. Corporate Services assigns such sales and purchases among IPL and WPL based on statements received from MISO. The amounts billed for services provided, sales credited and purchases for the three and nine months ended September 30 were as follows (in millions): IPL WPL Three Months Nine Months Three Months Nine Months 2022 2021 2022 2021 2022 2021 2022 2021 Corporate Services billings $45 $50 $136 $138 $39 $37 $117 $113 Sales credited 11 4 11 9 31 16 62 23 Purchases billed 119 105 342 347 42 24 103 71 Net intercompany payables to Corporate Services were as follows (in millions): IPL WPL September 30, 2022 December 31, 2021 September 30, 2022 December 31, 2021 Net payables to Corporate Services $113 $110 $88 $83 ATC - Pursuant to various agreements, WPL receives a range of transmission services from ATC. WPL provides operation, maintenance, and construction services to ATC. WPL and ATC also bill each other for use of shared facilities owned by each party. The related amounts billed between the parties for the three and nine months ended September 30 were as follows (in millions): Three Months Nine Months 2022 2021 2022 2021 ATC billings to WPL $38 $29 $107 $91 WPL billings to ATC 6 4 14 13 WPL owed ATC net amounts of $9 million as of September 30, 2022 and $10 million as of December 31, 2021.
IPL [Member]
Related Party Transactions [Line Items]
Related Parties	RELATED PARTIES Service Agreements - Pursuant to service agreements, IPL and WPL receive various administrative and general services from an affiliate, Corporate Services. These services are billed to IPL and WPL at cost based on expenses incurred by Corporate Services for the benefit of IPL and WPL, respectively. These costs consisted primarily of employee compensation and benefits, fees associated with various professional services, depreciation and amortization of property, plant and equipment, and a return on net assets. Corporate Services also acts as agent on behalf of IPL and WPL pursuant to the service agreements. As agent, Corporate Services enters into energy, capacity, ancillary services, and transmission sale and purchase transactions within MISO. Corporate Services assigns such sales and purchases among IPL and WPL based on statements received from MISO. The amounts billed for services provided, sales credited and purchases for the three and nine months ended September 30 were as follows (in millions): IPL WPL Three Months Nine Months Three Months Nine Months 2022 2021 2022 2021 2022 2021 2022 2021 Corporate Services billings $45 $50 $136 $138 $39 $37 $117 $113 Sales credited 11 4 11 9 31 16 62 23 Purchases billed 119 105 342 347 42 24 103 71 Net intercompany payables to Corporate Services were as follows (in millions): IPL WPL September 30, 2022 December 31, 2021 September 30, 2022 December 31, 2021 Net payables to Corporate Services $113 $110 $88 $83
WPL [Member]
Related Party Transactions [Line Items]
Related Parties	RELATED PARTIES Service Agreements - Pursuant to service agreements, IPL and WPL receive various administrative and general services from an affiliate, Corporate Services. These services are billed to IPL and WPL at cost based on expenses incurred by Corporate Services for the benefit of IPL and WPL, respectively. These costs consisted primarily of employee compensation and benefits, fees associated with various professional services, depreciation and amortization of property, plant and equipment, and a return on net assets. Corporate Services also acts as agent on behalf of IPL and WPL pursuant to the service agreements. As agent, Corporate Services enters into energy, capacity, ancillary services, and transmission sale and purchase transactions within MISO. Corporate Services assigns such sales and purchases among IPL and WPL based on statements received from MISO. The amounts billed for services provided, sales credited and purchases for the three and nine months ended September 30 were as follows (in millions): IPL WPL Three Months Nine Months Three Months Nine Months 2022 2021 2022 2021 2022 2021 2022 2021 Corporate Services billings $45 $50 $136 $138 $39 $37 $117 $113 Sales credited 11 4 11 9 31 16 62 23 Purchases billed 119 105 342 347 42 24 103 71 Net intercompany payables to Corporate Services were as follows (in millions): IPL WPL September 30, 2022 December 31, 2021 September 30, 2022 December 31, 2021 Net payables to Corporate Services $113 $110 $88 $83 ATC - Pursuant to various agreements, WPL receives a range of transmission services from ATC. WPL provides operation, maintenance, and construction services to ATC. WPL and ATC also bill each other for use of shared facilities owned by each party. The related amounts billed between the parties for the three and nine months ended September 30 were as follows (in millions): Three Months Nine Months 2022 2021 2022 2021 ATC billings to WPL $38 $29 $107 $91 WPL billings to ATC 6 4 14 13 WPL owed ATC net amounts of $9 million as of September 30, 2022 and $10 million as of December 31, 2021.

Summary Of Significant Accoun_2

Summary Of Significant Accounting Policies (Policy)	9 Months Ended
	Sep. 30, 2022
General, Basis of Accounting	The interim unaudited Financial Statements included herein have been prepared pursuant to the rules and regulations of the SEC. Accordingly, certain information and note disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted, although management believes that the disclosures are adequate to make the information presented not misleading. These Financial Statements should be read in conjunction with the financial statements and the notes thereto included in the 2021 Form 10-K .
General, Use of Estimates	A change in management’s estimates or assumptions could have a material impact on financial condition and results of operations during the period in which such change occurred.
General, Reclassification	Certain prior period amounts in the Financial Statements and Notes have been reclassified to conform to the current period presentation for comparative purposes.
Cash and Cash Equivalents	At September 30, 2022, Alliant Energy’s, IPL’s and WPL’s cash and cash equivalents included $334 million, $39 million and $295 million of money market fund investments, respectively, with weighted average interest rates of 3%.
Variable Interest Entities	In 2022, WPL 2022 Solar Holdco, LLC was formed as a joint venture to own and operate project companies responsible for the construction, ownership and operation of various solar generation assets. Members of the joint venture were a WPL subsidiary (the managing member) and a tax equity partner. In the second quarter of 2022, the WPL subsidiary and the tax equity partner contributed $62 million and $29 million, respectively, to WPL 2022 Solar Holdco, LLC in exchange for membership interests, and $88 million of the contributed funds were paid to WPL in exchange for equity interests in the project companies. In the second quarter of 2022, Alliant Energy and WPL consolidated this joint venture as it was a VIE in which WPL held a variable interest, and WPL controlled decisions that were significant to the joint venture’s ongoing operations and economic results (i.e., WPL was the primary beneficiary). In August 2022, the Inflation Reduction Act of 2022 was enacted. Following its enactment, WPL evaluated the provisions of the new legislation and determined that retaining full ownership of the solar projects is expected to result in lower costs for its customers. As a result, in the third quarter of 2022, WPL and the tax equity partner terminated the tax equity partnership, and WPL returned the $29 million of initial funding to the tax equity partner. Alliant Energy and WPL no longer expect their solar generation project construction costs to be financed with capital from tax equity partners, which would result in higher rate base amounts compared to those previously approved by the PSCW for WPL’s planned approximately 1,100 MW of solar generation. Alliant Energy and WPL concluded that no disallowance of anticipated higher rate base amounts was required as of September 30, 2022 given full ownership of WPL's planned solar generation is expected to result in lower costs for WPL's customers. Refer to Note 6 for discussion of a noncontrolling interest that was initially associated with the joint venture prior to the termination of the tax equity partnership.
IPL [Member]
General, Basis of Accounting	The interim unaudited Financial Statements included herein have been prepared pursuant to the rules and regulations of the SEC. Accordingly, certain information and note disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted, although management believes that the disclosures are adequate to make the information presented not misleading. These Financial Statements should be read in conjunction with the financial statements and the notes thereto included in the 2021 Form 10-K .
General, Use of Estimates	A change in management’s estimates or assumptions could have a material impact on financial condition and results of operations during the period in which such change occurred.
General, Reclassification	Certain prior period amounts in the Financial Statements and Notes have been reclassified to conform to the current period presentation for comparative purposes.
Cash and Cash Equivalents	At September 30, 2022, Alliant Energy’s, IPL’s and WPL’s cash and cash equivalents included $334 million, $39 million and $295 million of money market fund investments, respectively, with weighted average interest rates of 3%.
WPL [Member]
General, Basis of Accounting	The interim unaudited Financial Statements included herein have been prepared pursuant to the rules and regulations of the SEC. Accordingly, certain information and note disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted, although management believes that the disclosures are adequate to make the information presented not misleading. These Financial Statements should be read in conjunction with the financial statements and the notes thereto included in the 2021 Form 10-K .
General, Use of Estimates	A change in management’s estimates or assumptions could have a material impact on financial condition and results of operations during the period in which such change occurred.
General, Reclassification	Certain prior period amounts in the Financial Statements and Notes have been reclassified to conform to the current period presentation for comparative purposes.
Cash and Cash Equivalents	At September 30, 2022, Alliant Energy’s, IPL’s and WPL’s cash and cash equivalents included $334 million, $39 million and $295 million of money market fund investments, respectively, with weighted average interest rates of 3%.
Variable Interest Entities	In 2022, WPL 2022 Solar Holdco, LLC was formed as a joint venture to own and operate project companies responsible for the construction, ownership and operation of various solar generation assets. Members of the joint venture were a WPL subsidiary (the managing member) and a tax equity partner. In the second quarter of 2022, the WPL subsidiary and the tax equity partner contributed $62 million and $29 million, respectively, to WPL 2022 Solar Holdco, LLC in exchange for membership interests, and $88 million of the contributed funds were paid to WPL in exchange for equity interests in the project companies. In the second quarter of 2022, Alliant Energy and WPL consolidated this joint venture as it was a VIE in which WPL held a variable interest, and WPL controlled decisions that were significant to the joint venture’s ongoing operations and economic results (i.e., WPL was the primary beneficiary). In August 2022, the Inflation Reduction Act of 2022 was enacted. Following its enactment, WPL evaluated the provisions of the new legislation and determined that retaining full ownership of the solar projects is expected to result in lower costs for its customers. As a result, in the third quarter of 2022, WPL and the tax equity partner terminated the tax equity partnership, and WPL returned the $29 million of initial funding to the tax equity partner. Alliant Energy and WPL no longer expect their solar generation project construction costs to be financed with capital from tax equity partners, which would result in higher rate base amounts compared to those previously approved by the PSCW for WPL’s planned approximately 1,100 MW of solar generation. Alliant Energy and WPL concluded that no disallowance of anticipated higher rate base amounts was required as of September 30, 2022 given full ownership of WPL's planned solar generation is expected to result in lower costs for WPL's customers. Refer to Note 6 for discussion of a noncontrolling interest that was initially associated with the joint venture prior to the termination of the tax equity partnership.

Regulatory Matters (Tables)

Regulatory Matters (Tables)	9 Months Ended
	Sep. 30, 2022
Regulatory Assets [Line Items]
Regulatory Assets	Regulatory assets were comprised of the following items (in millions): Alliant Energy IPL WPL September 30, December 31, September 30, December 31, September 30, December 31, Tax-related $913 $934 $842 $884 $71 $50 Pension and OPEB costs 436 462 216 228 220 234 Asset retirement obligations 145 128 104 89 41 39 Commodity cost recovery 129 42 2 2 127 40 Derivatives 102 8 67 4 35 4 Assets retired early 75 92 56 66 19 26 IPL’s DAEC PPA amendment 72 90 72 90 — — WPL’s Western Wisconsin gas distribution expansion investments 49 52 — — 49 52 Other 120 132 64 80 56 52 $2,041 $1,940 $1,423 $1,443 $618 $497
Regulatory Liabilities	Regulatory liabilities were comprised of the following items (in millions): Alliant Energy IPL WPL September 30, December 31, September 30, December 31, September 30, December 31, Tax-related $582 $585 $304 $312 $278 $273 Cost of removal obligations 398 384 258 252 140 132 Derivatives 312 166 164 77 148 89 WPL’s West Riverside liquidated damages 33 36 — — 33 36 Electric transmission cost recovery 16 51 4 27 12 24 Other 46 49 31 23 15 26 $1,387 $1,271 $761 $691 $626 $580
IPL [Member]
Regulatory Assets [Line Items]
Regulatory Assets	Regulatory assets were comprised of the following items (in millions): Alliant Energy IPL WPL September 30, December 31, September 30, December 31, September 30, December 31, Tax-related $913 $934 $842 $884 $71 $50 Pension and OPEB costs 436 462 216 228 220 234 Asset retirement obligations 145 128 104 89 41 39 Commodity cost recovery 129 42 2 2 127 40 Derivatives 102 8 67 4 35 4 Assets retired early 75 92 56 66 19 26 IPL’s DAEC PPA amendment 72 90 72 90 — — WPL’s Western Wisconsin gas distribution expansion investments 49 52 — — 49 52 Other 120 132 64 80 56 52 $2,041 $1,940 $1,423 $1,443 $618 $497
Regulatory Liabilities	Regulatory liabilities were comprised of the following items (in millions): Alliant Energy IPL WPL September 30, December 31, September 30, December 31, September 30, December 31, Tax-related $582 $585 $304 $312 $278 $273 Cost of removal obligations 398 384 258 252 140 132 Derivatives 312 166 164 77 148 89 WPL’s West Riverside liquidated damages 33 36 — — 33 36 Electric transmission cost recovery 16 51 4 27 12 24 Other 46 49 31 23 15 26 $1,387 $1,271 $761 $691 $626 $580
WPL [Member]
Regulatory Assets [Line Items]
Regulatory Assets	Regulatory assets were comprised of the following items (in millions): Alliant Energy IPL WPL September 30, December 31, September 30, December 31, September 30, December 31, Tax-related $913 $934 $842 $884 $71 $50 Pension and OPEB costs 436 462 216 228 220 234 Asset retirement obligations 145 128 104 89 41 39 Commodity cost recovery 129 42 2 2 127 40 Derivatives 102 8 67 4 35 4 Assets retired early 75 92 56 66 19 26 IPL’s DAEC PPA amendment 72 90 72 90 — — WPL’s Western Wisconsin gas distribution expansion investments 49 52 — — 49 52 Other 120 132 64 80 56 52 $2,041 $1,940 $1,423 $1,443 $618 $497
Regulatory Liabilities	Regulatory liabilities were comprised of the following items (in millions): Alliant Energy IPL WPL September 30, December 31, September 30, December 31, September 30, December 31, Tax-related $582 $585 $304 $312 $278 $273 Cost of removal obligations 398 384 258 252 140 132 Derivatives 312 166 164 77 148 89 WPL’s West Riverside liquidated damages 33 36 — — 33 36 Electric transmission cost recovery 16 51 4 27 12 24 Other 46 49 31 23 15 26 $1,387 $1,271 $761 $691 $626 $580

Receivables (Tables)

Receivables (Tables)	9 Months Ended
	Sep. 30, 2022
Receivables [Line Items]
Maximum And Average Outstanding Cash Proceeds	IPL’s maximum and average outstanding cash proceeds (based on daily outstanding balances) related to the sales of accounts receivable program for the three and nine months ended September 30 were as follows (in millions): Three Months Nine Months 2022 2021 2022 2021 Maximum outstanding aggregate cash proceeds $36 $110 $66 $110 Average outstanding aggregate cash proceeds 3 65 8 52
Attributes of Receivables Sold Under the Receivables Agreement	The attributes of IPL’s receivables sold under the Receivables Agreement were as follows (in millions): September 30, 2022 December 31, 2021 Customer accounts receivable $169 $125 Unbilled utility revenues 92 104 Receivables sold to third party 261 229 Less: cash proceeds 1 1 Deferred proceeds 260 228 Less: allowance for expected credit losses 12 14 Fair value of deferred proceeds $248 $214
Additional Attributes Of Receivables Sold Under The Receivables Agreement	Additional attributes of IPL’s receivables sold under the Receivables Agreement for the three and nine months ended September 30 were as follows (in millions): Three Months Nine Months 2022 2021 2022 2021 Collections $670 $607 $1,731 $1,589 Write-offs, net of recoveries 3 4 6 7
IPL [Member]
Receivables [Line Items]
Maximum And Average Outstanding Cash Proceeds	IPL’s maximum and average outstanding cash proceeds (based on daily outstanding balances) related to the sales of accounts receivable program for the three and nine months ended September 30 were as follows (in millions): Three Months Nine Months 2022 2021 2022 2021 Maximum outstanding aggregate cash proceeds $36 $110 $66 $110 Average outstanding aggregate cash proceeds 3 65 8 52
Attributes of Receivables Sold Under the Receivables Agreement	The attributes of IPL’s receivables sold under the Receivables Agreement were as follows (in millions): September 30, 2022 December 31, 2021 Customer accounts receivable $169 $125 Unbilled utility revenues 92 104 Receivables sold to third party 261 229 Less: cash proceeds 1 1 Deferred proceeds 260 228 Less: allowance for expected credit losses 12 14 Fair value of deferred proceeds $248 $214
Additional Attributes Of Receivables Sold Under The Receivables Agreement	Additional attributes of IPL’s receivables sold under the Receivables Agreement for the three and nine months ended September 30 were as follows (in millions): Three Months Nine Months 2022 2021 2022 2021 Collections $670 $607 $1,731 $1,589 Write-offs, net of recoveries 3 4 6 7

Investments (Tables)

Investments (Tables)	9 Months Ended
	Sep. 30, 2022
Schedule of Equity Method Investments [Line Items]
Unconsolidated Equity Investments	Alliant Energy’s equity (income) loss from unconsolidated investments accounted for under the equity method of accounting for the three and nine months ended September 30 was as follows (in millions): Three Months Nine Months 2022 2021 2022 2021 ATC Holdings ($7) ($12) ($29) ($34) Other 2 (1) (8) (13) ($5) ($13) ($37) ($47)

Common Equity (Tables)

Common Equity (Tables)	9 Months Ended
	Sep. 30, 2022
Schedule of Capitalization, Equity [Line Items]
Common Share Activity	A summary of Alliant Energy’s common stock activity was as follows: Shares outstanding, January 1, 2022 250,474,529 Shareowner Direct Plan 324,533 Equity-based compensation plans 222,768 Shares outstanding, September 30, 2022 251,021,830
Changes in Shareowners' Equity	A summary of changes in shareowners’ equity was as follows (in millions): Alliant Energy Total Alliant Energy Common Equity Accumulated Shares in Additional Other Deferred Common Paid-In Retained Comprehensive Compensation Noncontrolling Total Stock Capital Earnings Loss Trust Interest Equity Three Months Ended September 30, 2022 Beginning balance, June 30, 2022 $3 $2,759 $3,387 $— ($12) $29 $6,166 Net income attributable to Alliant Energy common shareowners 227 227 Common stock dividends ($0.4275 per share) (106) (106) Shareowner Direct Plan issuances 6 6 Equity-based compensation plans and other 2 (1) 1 Distributions to noncontrolling interest (29) (29) Ending balance, September 30, 2022 $3 $2,767 $3,508 $— ($13) $— $6,265 Alliant Energy Total Alliant Energy Common Equity Accumulated Shares in Cumulative Additional Other Deferred Preferred Common Paid-In Retained Comprehensive Compensation Stock Total Stock Capital Earnings Loss Trust of IPL Equity Three Months Ended September 30, 2021 Beginning balance, June 30, 2021 $3 $2,722 $3,106 ($1) ($11) $200 $6,019 Net income attributable to Alliant Energy common shareowners 256 256 Common stock dividends ($0.4025 per share) (101) (101) Shareowner Direct Plan issuances 6 6 Equity-based compensation plans and other 5 5 Ending balance, September 30, 2021 $3 $2,733 $3,261 ($1) ($11) $200 $6,185 Alliant Energy Total Alliant Energy Common Equity Accumulated Shares in Additional Other Deferred Common Paid-In Retained Comprehensive Compensation Noncontrolling Total Stock Capital Earnings Loss Trust Interest Equity Nine Months Ended September 30, 2022 Beginning balance, December 31, 2021 $3 $2,749 $3,250 $— ($12) $— $5,990 Net income attributable to Alliant Energy common shareowners 579 579 Common stock dividends ($1.2825 per share) (322) (322) Shareowner Direct Plan issuances 19 19 Equity-based compensation plans and other (1) 1 (1) (1) Contributions from noncontrolling interest 29 29 Distributions to noncontrolling interest (29) (29) Ending balance, September 30, 2022 $3 $2,767 $3,508 $— ($13) $— $6,265 Alliant Energy Total Alliant Energy Common Equity Accumulated Shares in Cumulative Additional Other Deferred Preferred Common Paid-In Retained Comprehensive Compensation Stock Total Stock Capital Earnings Loss Trust of IPL Equity Nine Months Ended September 30, 2021 Beginning balance, December 31, 2020 $2 $2,704 $2,994 ($1) ($11) $200 $5,888 Net income attributable to Alliant Energy common shareowners 571 571 Common stock dividends ($1.2075 per share) (304) (304) Shareowner Direct Plan issuances 1 21 22 Equity-based compensation plans and other 8 8 Ending balance, September 30, 2021 $3 $2,733 $3,261 ($1) ($11) $200 $6,185 IPL Total IPL Common Equity Additional Cumulative Common Paid-In Retained Preferred Total Stock Capital Earnings Stock Equity Three Months Ended September 30, 2022 Beginning balance, June 30, 2022 $33 $2,807 $942 $— $3,782 Net income available for common stock 154 154 Common stock dividends (80) (80) Ending balance, September 30, 2022 $33 $2,807 $1,016 $— $3,856 Three Months Ended September 30, 2021 Beginning balance, June 30, 2021 $33 $2,802 $944 $200 $3,979 Net income available for common stock 157 157 Common stock dividends (101) (101) Ending balance, September 30, 2021 $33 $2,802 $1,000 $200 $4,035 IPL Total IPL Common Equity Additional Cumulative Common Paid-In Retained Preferred Total Stock Capital Earnings Stock Equity Nine Months Ended September 30, 2022 Beginning balance, December 31, 2021 $33 $2,807 $929 $— $3,769 Net income available for common stock 327 327 Common stock dividends (240) (240) Ending balance, September 30, 2022 $33 $2,807 $1,016 $— $3,856 Nine Months Ended September 30, 2021 Beginning balance, December 31, 2020 $33 $2,752 $979 $200 $3,964 Net income available for common stock 322 322 Common stock dividends (301) (301) Capital contributions from parent 50 50 Ending balance, September 30, 2021 $33 $2,802 $1,000 $200 $4,035 WPL Total WPL Common Equity Additional Common Paid-In Retained Noncontrolling Total Stock Capital Earnings Interest Equity Three Months Ended September 30, 2022 Beginning balance, June 30, 2022 $66 $1,968 $1,120 $29 $3,183 Net income 91 91 Common stock dividends (44) (44) Capital contributions from parent 155 155 Distributions to noncontrolling interest (29) (29) Ending balance, September 30, 2022 $66 $2,123 $1,167 $— $3,356 Three Months Ended September 30, 2021 Beginning balance, June 30, 2021 $66 $1,669 $990 $— $2,725 Net income 93 93 Common stock dividends (41) (41) Capital contributions from parent 35 35 Ending balance, September 30, 2021 $66 $1,704 $1,042 $— $2,812 WPL Total WPL Common Equity Additional Common Paid-In Retained Noncontrolling Total Stock Capital Earnings Interest Equity Nine Months Ended September 30, 2022 Beginning balance, December 31, 2021 $66 $1,704 $1,053 $— $2,823 Net income 247 247 Common stock dividends (133) (133) Capital contributions from parent 420 420 Contributions from noncontrolling interest 29 29 Distributions to noncontrolling interest (29) (29) Other (1) (1) Ending balance, September 30, 2022 $66 $2,123 $1,167 $— $3,356 Nine Months Ended September 30, 2021 Beginning balance, December 31, 2020 $66 $1,459 $953 $— $2,478 Net income 215 215 Common stock dividends (126) (126) Capital contributions from parent 245 245 Ending balance, September 30, 2021 $66 $1,704 $1,042 $— $2,812
IPL [Member]
Schedule of Capitalization, Equity [Line Items]
Changes in Shareowners' Equity	A summary of changes in shareowners’ equity was as follows (in millions): Alliant Energy Total Alliant Energy Common Equity Accumulated Shares in Additional Other Deferred Common Paid-In Retained Comprehensive Compensation Noncontrolling Total Stock Capital Earnings Loss Trust Interest Equity Three Months Ended September 30, 2022 Beginning balance, June 30, 2022 $3 $2,759 $3,387 $— ($12) $29 $6,166 Net income attributable to Alliant Energy common shareowners 227 227 Common stock dividends ($0.4275 per share) (106) (106) Shareowner Direct Plan issuances 6 6 Equity-based compensation plans and other 2 (1) 1 Distributions to noncontrolling interest (29) (29) Ending balance, September 30, 2022 $3 $2,767 $3,508 $— ($13) $— $6,265 Alliant Energy Total Alliant Energy Common Equity Accumulated Shares in Cumulative Additional Other Deferred Preferred Common Paid-In Retained Comprehensive Compensation Stock Total Stock Capital Earnings Loss Trust of IPL Equity Three Months Ended September 30, 2021 Beginning balance, June 30, 2021 $3 $2,722 $3,106 ($1) ($11) $200 $6,019 Net income attributable to Alliant Energy common shareowners 256 256 Common stock dividends ($0.4025 per share) (101) (101) Shareowner Direct Plan issuances 6 6 Equity-based compensation plans and other 5 5 Ending balance, September 30, 2021 $3 $2,733 $3,261 ($1) ($11) $200 $6,185 Alliant Energy Total Alliant Energy Common Equity Accumulated Shares in Additional Other Deferred Common Paid-In Retained Comprehensive Compensation Noncontrolling Total Stock Capital Earnings Loss Trust Interest Equity Nine Months Ended September 30, 2022 Beginning balance, December 31, 2021 $3 $2,749 $3,250 $— ($12) $— $5,990 Net income attributable to Alliant Energy common shareowners 579 579 Common stock dividends ($1.2825 per share) (322) (322) Shareowner Direct Plan issuances 19 19 Equity-based compensation plans and other (1) 1 (1) (1) Contributions from noncontrolling interest 29 29 Distributions to noncontrolling interest (29) (29) Ending balance, September 30, 2022 $3 $2,767 $3,508 $— ($13) $— $6,265 Alliant Energy Total Alliant Energy Common Equity Accumulated Shares in Cumulative Additional Other Deferred Preferred Common Paid-In Retained Comprehensive Compensation Stock Total Stock Capital Earnings Loss Trust of IPL Equity Nine Months Ended September 30, 2021 Beginning balance, December 31, 2020 $2 $2,704 $2,994 ($1) ($11) $200 $5,888 Net income attributable to Alliant Energy common shareowners 571 571 Common stock dividends ($1.2075 per share) (304) (304) Shareowner Direct Plan issuances 1 21 22 Equity-based compensation plans and other 8 8 Ending balance, September 30, 2021 $3 $2,733 $3,261 ($1) ($11) $200 $6,185 IPL Total IPL Common Equity Additional Cumulative Common Paid-In Retained Preferred Total Stock Capital Earnings Stock Equity Three Months Ended September 30, 2022 Beginning balance, June 30, 2022 $33 $2,807 $942 $— $3,782 Net income available for common stock 154 154 Common stock dividends (80) (80) Ending balance, September 30, 2022 $33 $2,807 $1,016 $— $3,856 Three Months Ended September 30, 2021 Beginning balance, June 30, 2021 $33 $2,802 $944 $200 $3,979 Net income available for common stock 157 157 Common stock dividends (101) (101) Ending balance, September 30, 2021 $33 $2,802 $1,000 $200 $4,035 IPL Total IPL Common Equity Additional Cumulative Common Paid-In Retained Preferred Total Stock Capital Earnings Stock Equity Nine Months Ended September 30, 2022 Beginning balance, December 31, 2021 $33 $2,807 $929 $— $3,769 Net income available for common stock 327 327 Common stock dividends (240) (240) Ending balance, September 30, 2022 $33 $2,807 $1,016 $— $3,856 Nine Months Ended September 30, 2021 Beginning balance, December 31, 2020 $33 $2,752 $979 $200 $3,964 Net income available for common stock 322 322 Common stock dividends (301) (301) Capital contributions from parent 50 50 Ending balance, September 30, 2021 $33 $2,802 $1,000 $200 $4,035 WPL Total WPL Common Equity Additional Common Paid-In Retained Noncontrolling Total Stock Capital Earnings Interest Equity Three Months Ended September 30, 2022 Beginning balance, June 30, 2022 $66 $1,968 $1,120 $29 $3,183 Net income 91 91 Common stock dividends (44) (44) Capital contributions from parent 155 155 Distributions to noncontrolling interest (29) (29) Ending balance, September 30, 2022 $66 $2,123 $1,167 $— $3,356 Three Months Ended September 30, 2021 Beginning balance, June 30, 2021 $66 $1,669 $990 $— $2,725 Net income 93 93 Common stock dividends (41) (41) Capital contributions from parent 35 35 Ending balance, September 30, 2021 $66 $1,704 $1,042 $— $2,812 WPL Total WPL Common Equity Additional Common Paid-In Retained Noncontrolling Total Stock Capital Earnings Interest Equity Nine Months Ended September 30, 2022 Beginning balance, December 31, 2021 $66 $1,704 $1,053 $— $2,823 Net income 247 247 Common stock dividends (133) (133) Capital contributions from parent 420 420 Contributions from noncontrolling interest 29 29 Distributions to noncontrolling interest (29) (29) Other (1) (1) Ending balance, September 30, 2022 $66 $2,123 $1,167 $— $3,356 Nine Months Ended September 30, 2021 Beginning balance, December 31, 2020 $66 $1,459 $953 $— $2,478 Net income 215 215 Common stock dividends (126) (126) Capital contributions from parent 245 245 Ending balance, September 30, 2021 $66 $1,704 $1,042 $— $2,812
WPL [Member]
Schedule of Capitalization, Equity [Line Items]
Changes in Shareowners' Equity	A summary of changes in shareowners’ equity was as follows (in millions): Alliant Energy Total Alliant Energy Common Equity Accumulated Shares in Additional Other Deferred Common Paid-In Retained Comprehensive Compensation Noncontrolling Total Stock Capital Earnings Loss Trust Interest Equity Three Months Ended September 30, 2022 Beginning balance, June 30, 2022 $3 $2,759 $3,387 $— ($12) $29 $6,166 Net income attributable to Alliant Energy common shareowners 227 227 Common stock dividends ($0.4275 per share) (106) (106) Shareowner Direct Plan issuances 6 6 Equity-based compensation plans and other 2 (1) 1 Distributions to noncontrolling interest (29) (29) Ending balance, September 30, 2022 $3 $2,767 $3,508 $— ($13) $— $6,265 Alliant Energy Total Alliant Energy Common Equity Accumulated Shares in Cumulative Additional Other Deferred Preferred Common Paid-In Retained Comprehensive Compensation Stock Total Stock Capital Earnings Loss Trust of IPL Equity Three Months Ended September 30, 2021 Beginning balance, June 30, 2021 $3 $2,722 $3,106 ($1) ($11) $200 $6,019 Net income attributable to Alliant Energy common shareowners 256 256 Common stock dividends ($0.4025 per share) (101) (101) Shareowner Direct Plan issuances 6 6 Equity-based compensation plans and other 5 5 Ending balance, September 30, 2021 $3 $2,733 $3,261 ($1) ($11) $200 $6,185 Alliant Energy Total Alliant Energy Common Equity Accumulated Shares in Additional Other Deferred Common Paid-In Retained Comprehensive Compensation Noncontrolling Total Stock Capital Earnings Loss Trust Interest Equity Nine Months Ended September 30, 2022 Beginning balance, December 31, 2021 $3 $2,749 $3,250 $— ($12) $— $5,990 Net income attributable to Alliant Energy common shareowners 579 579 Common stock dividends ($1.2825 per share) (322) (322) Shareowner Direct Plan issuances 19 19 Equity-based compensation plans and other (1) 1 (1) (1) Contributions from noncontrolling interest 29 29 Distributions to noncontrolling interest (29) (29) Ending balance, September 30, 2022 $3 $2,767 $3,508 $— ($13) $— $6,265 Alliant Energy Total Alliant Energy Common Equity Accumulated Shares in Cumulative Additional Other Deferred Preferred Common Paid-In Retained Comprehensive Compensation Stock Total Stock Capital Earnings Loss Trust of IPL Equity Nine Months Ended September 30, 2021 Beginning balance, December 31, 2020 $2 $2,704 $2,994 ($1) ($11) $200 $5,888 Net income attributable to Alliant Energy common shareowners 571 571 Common stock dividends ($1.2075 per share) (304) (304) Shareowner Direct Plan issuances 1 21 22 Equity-based compensation plans and other 8 8 Ending balance, September 30, 2021 $3 $2,733 $3,261 ($1) ($11) $200 $6,185 IPL Total IPL Common Equity Additional Cumulative Common Paid-In Retained Preferred Total Stock Capital Earnings Stock Equity Three Months Ended September 30, 2022 Beginning balance, June 30, 2022 $33 $2,807 $942 $— $3,782 Net income available for common stock 154 154 Common stock dividends (80) (80) Ending balance, September 30, 2022 $33 $2,807 $1,016 $— $3,856 Three Months Ended September 30, 2021 Beginning balance, June 30, 2021 $33 $2,802 $944 $200 $3,979 Net income available for common stock 157 157 Common stock dividends (101) (101) Ending balance, September 30, 2021 $33 $2,802 $1,000 $200 $4,035 IPL Total IPL Common Equity Additional Cumulative Common Paid-In Retained Preferred Total Stock Capital Earnings Stock Equity Nine Months Ended September 30, 2022 Beginning balance, December 31, 2021 $33 $2,807 $929 $— $3,769 Net income available for common stock 327 327 Common stock dividends (240) (240) Ending balance, September 30, 2022 $33 $2,807 $1,016 $— $3,856 Nine Months Ended September 30, 2021 Beginning balance, December 31, 2020 $33 $2,752 $979 $200 $3,964 Net income available for common stock 322 322 Common stock dividends (301) (301) Capital contributions from parent 50 50 Ending balance, September 30, 2021 $33 $2,802 $1,000 $200 $4,035 WPL Total WPL Common Equity Additional Common Paid-In Retained Noncontrolling Total Stock Capital Earnings Interest Equity Three Months Ended September 30, 2022 Beginning balance, June 30, 2022 $66 $1,968 $1,120 $29 $3,183 Net income 91 91 Common stock dividends (44) (44) Capital contributions from parent 155 155 Distributions to noncontrolling interest (29) (29) Ending balance, September 30, 2022 $66 $2,123 $1,167 $— $3,356 Three Months Ended September 30, 2021 Beginning balance, June 30, 2021 $66 $1,669 $990 $— $2,725 Net income 93 93 Common stock dividends (41) (41) Capital contributions from parent 35 35 Ending balance, September 30, 2021 $66 $1,704 $1,042 $— $2,812 WPL Total WPL Common Equity Additional Common Paid-In Retained Noncontrolling Total Stock Capital Earnings Interest Equity Nine Months Ended September 30, 2022 Beginning balance, December 31, 2021 $66 $1,704 $1,053 $— $2,823 Net income 247 247 Common stock dividends (133) (133) Capital contributions from parent 420 420 Contributions from noncontrolling interest 29 29 Distributions to noncontrolling interest (29) (29) Other (1) (1) Ending balance, September 30, 2022 $66 $2,123 $1,167 $— $3,356 Nine Months Ended September 30, 2021 Beginning balance, December 31, 2020 $66 $1,459 $953 $— $2,478 Net income 215 215 Common stock dividends (126) (126) Capital contributions from parent 245 245 Ending balance, September 30, 2021 $66 $1,704 $1,042 $— $2,812

Debt (Tables)

Debt (Tables)	9 Months Ended
	Sep. 30, 2022
Short-term Debt [Line Items]
Other Short-Term Borrowings	Information regarding Alliant Energy’s, IPL’s and WPL’s commercial paper classified as short-term debt was as follows (dollars in millions): September 30, 2022 Alliant Energy IPL WPL Amount outstanding $383 $— $— Weighted average interest rates 3.4% N/A N/A Available credit facility capacity $617 $250 $300 Alliant Energy IPL WPL Three Months Ended September 30 2022 2021 2022 2021 2022 2021 Maximum amount outstanding (based on daily outstanding balances) $449 $648 $— $8 $251 $320 Average amount outstanding (based on daily outstanding balances) $353 $560 $— $— $110 $221 Weighted average interest rates 2.4% 0.2% —% 0.2% 2.0% 0.1% Nine Months Ended September 30 Maximum amount outstanding (based on daily outstanding balances) $577 $648 $— $19 $252 $320 Average amount outstanding (based on daily outstanding balances) $377 $479 $— $— $160 $196 Weighted average interest rates 1.2% 0.2% —% 0.2% 0.9% 0.1%
IPL [Member]
Short-term Debt [Line Items]
Other Short-Term Borrowings	Information regarding Alliant Energy’s, IPL’s and WPL’s commercial paper classified as short-term debt was as follows (dollars in millions): September 30, 2022 Alliant Energy IPL WPL Amount outstanding $383 $— $— Weighted average interest rates 3.4% N/A N/A Available credit facility capacity $617 $250 $300 Alliant Energy IPL WPL Three Months Ended September 30 2022 2021 2022 2021 2022 2021 Maximum amount outstanding (based on daily outstanding balances) $449 $648 $— $8 $251 $320 Average amount outstanding (based on daily outstanding balances) $353 $560 $— $— $110 $221 Weighted average interest rates 2.4% 0.2% —% 0.2% 2.0% 0.1% Nine Months Ended September 30 Maximum amount outstanding (based on daily outstanding balances) $577 $648 $— $19 $252 $320 Average amount outstanding (based on daily outstanding balances) $377 $479 $— $— $160 $196 Weighted average interest rates 1.2% 0.2% —% 0.2% 0.9% 0.1%
WPL [Member]
Short-term Debt [Line Items]
Other Short-Term Borrowings	Information regarding Alliant Energy’s, IPL’s and WPL’s commercial paper classified as short-term debt was as follows (dollars in millions): September 30, 2022 Alliant Energy IPL WPL Amount outstanding $383 $— $— Weighted average interest rates 3.4% N/A N/A Available credit facility capacity $617 $250 $300 Alliant Energy IPL WPL Three Months Ended September 30 2022 2021 2022 2021 2022 2021 Maximum amount outstanding (based on daily outstanding balances) $449 $648 $— $8 $251 $320 Average amount outstanding (based on daily outstanding balances) $353 $560 $— $— $110 $221 Weighted average interest rates 2.4% 0.2% —% 0.2% 2.0% 0.1% Nine Months Ended September 30 Maximum amount outstanding (based on daily outstanding balances) $577 $648 $— $19 $252 $320 Average amount outstanding (based on daily outstanding balances) $377 $479 $— $— $160 $196 Weighted average interest rates 1.2% 0.2% —% 0.2% 0.9% 0.1%

Revenues (Tables)

Revenues (Tables)	9 Months Ended
	Sep. 30, 2022
Disaggregation of Revenue [Line Items]
Disaggregation of Revenue	Disaggregation of revenues from contracts with customers, which correlates to revenues for each reportable segment, was as follows (in millions): Alliant Energy IPL WPL Three Months Ended September 30 2022 2021 2022 2021 2022 2021 Electric Utility: Retail - residential $376 $348 $222 $207 $154 $141 Retail - commercial 243 232 165 160 78 72 Retail - industrial 289 265 172 158 117 107 Wholesale 68 55 19 18 49 37 Bulk power and other 63 39 18 12 45 27 Total Electric Utility 1,039 939 596 555 443 384 Gas Utility: Retail - residential 28 24 14 14 14 10 Retail - commercial 18 13 8 8 10 5 Retail - industrial 4 3 3 3 1 — Transportation/other 12 10 8 6 4 4 Total Gas Utility 62 50 33 31 29 19 Other Utility: Steam 9 9 9 9 — — Other utility 2 4 2 4 — — Total Other Utility 11 13 11 13 — — Non-Utility and Other: Travero and other 23 22 — — — — Total Non-Utility and Other 23 22 — — — — Total revenues $1,135 $1,024 $640 $599 $472 $403 Alliant Energy IPL WPL Nine Months Ended September 30 2022 2021 2022 2021 2022 2021 Electric Utility: Retail - residential $956 $868 $529 $488 $427 $380 Retail - commercial 628 579 411 385 217 194 Retail - industrial 743 677 418 386 325 291 Wholesale 168 142 49 44 119 98 Bulk power and other 129 91 31 40 98 51 Total Electric Utility 2,624 2,357 1,438 1,343 1,186 1,014 Gas Utility: Retail - residential 237 162 127 90 110 72 Retail - commercial 127 85 62 47 65 38 Retail - industrial 15 11 10 8 5 3 Transportation/other 39 31 25 20 14 11 Total Gas Utility 418 289 224 165 194 124 Other Utility: Steam 29 27 29 27 — — Other utility 6 9 5 8 1 1 Total Other Utility 35 36 34 35 1 1 Non-Utility and Other: Travero and other 70 60 — — — — Total Non-Utility and Other 70 60 — — — — Total revenues $3,147 $2,742 $1,696 $1,543 $1,381 $1,139
IPL [Member]
Disaggregation of Revenue [Line Items]
Disaggregation of Revenue	Disaggregation of revenues from contracts with customers, which correlates to revenues for each reportable segment, was as follows (in millions): Alliant Energy IPL WPL Three Months Ended September 30 2022 2021 2022 2021 2022 2021 Electric Utility: Retail - residential $376 $348 $222 $207 $154 $141 Retail - commercial 243 232 165 160 78 72 Retail - industrial 289 265 172 158 117 107 Wholesale 68 55 19 18 49 37 Bulk power and other 63 39 18 12 45 27 Total Electric Utility 1,039 939 596 555 443 384 Gas Utility: Retail - residential 28 24 14 14 14 10 Retail - commercial 18 13 8 8 10 5 Retail - industrial 4 3 3 3 1 — Transportation/other 12 10 8 6 4 4 Total Gas Utility 62 50 33 31 29 19 Other Utility: Steam 9 9 9 9 — — Other utility 2 4 2 4 — — Total Other Utility 11 13 11 13 — — Non-Utility and Other: Travero and other 23 22 — — — — Total Non-Utility and Other 23 22 — — — — Total revenues $1,135 $1,024 $640 $599 $472 $403 Alliant Energy IPL WPL Nine Months Ended September 30 2022 2021 2022 2021 2022 2021 Electric Utility: Retail - residential $956 $868 $529 $488 $427 $380 Retail - commercial 628 579 411 385 217 194 Retail - industrial 743 677 418 386 325 291 Wholesale 168 142 49 44 119 98 Bulk power and other 129 91 31 40 98 51 Total Electric Utility 2,624 2,357 1,438 1,343 1,186 1,014 Gas Utility: Retail - residential 237 162 127 90 110 72 Retail - commercial 127 85 62 47 65 38 Retail - industrial 15 11 10 8 5 3 Transportation/other 39 31 25 20 14 11 Total Gas Utility 418 289 224 165 194 124 Other Utility: Steam 29 27 29 27 — — Other utility 6 9 5 8 1 1 Total Other Utility 35 36 34 35 1 1 Non-Utility and Other: Travero and other 70 60 — — — — Total Non-Utility and Other 70 60 — — — — Total revenues $3,147 $2,742 $1,696 $1,543 $1,381 $1,139
WPL [Member]
Disaggregation of Revenue [Line Items]
Disaggregation of Revenue	Disaggregation of revenues from contracts with customers, which correlates to revenues for each reportable segment, was as follows (in millions): Alliant Energy IPL WPL Three Months Ended September 30 2022 2021 2022 2021 2022 2021 Electric Utility: Retail - residential $376 $348 $222 $207 $154 $141 Retail - commercial 243 232 165 160 78 72 Retail - industrial 289 265 172 158 117 107 Wholesale 68 55 19 18 49 37 Bulk power and other 63 39 18 12 45 27 Total Electric Utility 1,039 939 596 555 443 384 Gas Utility: Retail - residential 28 24 14 14 14 10 Retail - commercial 18 13 8 8 10 5 Retail - industrial 4 3 3 3 1 — Transportation/other 12 10 8 6 4 4 Total Gas Utility 62 50 33 31 29 19 Other Utility: Steam 9 9 9 9 — — Other utility 2 4 2 4 — — Total Other Utility 11 13 11 13 — — Non-Utility and Other: Travero and other 23 22 — — — — Total Non-Utility and Other 23 22 — — — — Total revenues $1,135 $1,024 $640 $599 $472 $403 Alliant Energy IPL WPL Nine Months Ended September 30 2022 2021 2022 2021 2022 2021 Electric Utility: Retail - residential $956 $868 $529 $488 $427 $380 Retail - commercial 628 579 411 385 217 194 Retail - industrial 743 677 418 386 325 291 Wholesale 168 142 49 44 119 98 Bulk power and other 129 91 31 40 98 51 Total Electric Utility 2,624 2,357 1,438 1,343 1,186 1,014 Gas Utility: Retail - residential 237 162 127 90 110 72 Retail - commercial 127 85 62 47 65 38 Retail - industrial 15 11 10 8 5 3 Transportation/other 39 31 25 20 14 11 Total Gas Utility 418 289 224 165 194 124 Other Utility: Steam 29 27 29 27 — — Other utility 6 9 5 8 1 1 Total Other Utility 35 36 34 35 1 1 Non-Utility and Other: Travero and other 70 60 — — — — Total Non-Utility and Other 70 60 — — — — Total revenues $3,147 $2,742 $1,696 $1,543 $1,381 $1,139

Income Taxes (Tables)

Income Taxes (Tables)	9 Months Ended
	Sep. 30, 2022
Income Taxes [Line Items]
Schedule Of Effective Income Tax Rates	Overall effective income tax rates, which were computed by dividing income tax expense (benefit) by income before income taxes, were as follows. The effective income tax rates were different than the federal statutory rate primarily due to state income taxes, production tax credits, amortization of excess deferred taxes and the effect of rate-making on property-related differences. The increases in Alliant Energy’s and WPL’s overall effective income tax rates for the three and nine months ended September 30, 2022 compared to the same periods in 2021 were primarily due to decreased amortization of excess deferred taxes primarily at WPL. Alliant Energy IPL WPL Three Months Nine Months Three Months Nine Months Three Months Nine Months 2022 2021 2022 2021 2022 2021 2022 2021 2022 2021 2022 2021 Overall income tax rate 6% (9%) 4% (13%) (12%) (8%) (14%) (11%) 15% (19%) 17% (24%)
Summary Of Tax Credit Carryforwards	At September 30, 2022, the remaining carryforwards and expiration dates were estimated as follows (in millions): Range of Expiration Dates Alliant Energy IPL WPL State net operating losses 2022-2042 $500 $9 $2 Federal tax credits 2022-2042 655 437 208
IPL [Member]
Income Taxes [Line Items]
Schedule Of Effective Income Tax Rates	Overall effective income tax rates, which were computed by dividing income tax expense (benefit) by income before income taxes, were as follows. The effective income tax rates were different than the federal statutory rate primarily due to state income taxes, production tax credits, amortization of excess deferred taxes and the effect of rate-making on property-related differences. The increases in Alliant Energy’s and WPL’s overall effective income tax rates for the three and nine months ended September 30, 2022 compared to the same periods in 2021 were primarily due to decreased amortization of excess deferred taxes primarily at WPL. Alliant Energy IPL WPL Three Months Nine Months Three Months Nine Months Three Months Nine Months 2022 2021 2022 2021 2022 2021 2022 2021 2022 2021 2022 2021 Overall income tax rate 6% (9%) 4% (13%) (12%) (8%) (14%) (11%) 15% (19%) 17% (24%)
Summary Of Tax Credit Carryforwards	At September 30, 2022, the remaining carryforwards and expiration dates were estimated as follows (in millions): Range of Expiration Dates Alliant Energy IPL WPL State net operating losses 2022-2042 $500 $9 $2 Federal tax credits 2022-2042 655 437 208
WPL [Member]
Income Taxes [Line Items]
Schedule Of Effective Income Tax Rates	Overall effective income tax rates, which were computed by dividing income tax expense (benefit) by income before income taxes, were as follows. The effective income tax rates were different than the federal statutory rate primarily due to state income taxes, production tax credits, amortization of excess deferred taxes and the effect of rate-making on property-related differences. The increases in Alliant Energy’s and WPL’s overall effective income tax rates for the three and nine months ended September 30, 2022 compared to the same periods in 2021 were primarily due to decreased amortization of excess deferred taxes primarily at WPL. Alliant Energy IPL WPL Three Months Nine Months Three Months Nine Months Three Months Nine Months 2022 2021 2022 2021 2022 2021 2022 2021 2022 2021 2022 2021 Overall income tax rate 6% (9%) 4% (13%) (12%) (8%) (14%) (11%) 15% (19%) 17% (24%)
Summary Of Tax Credit Carryforwards	At September 30, 2022, the remaining carryforwards and expiration dates were estimated as follows (in millions): Range of Expiration Dates Alliant Energy IPL WPL State net operating losses 2022-2042 $500 $9 $2 Federal tax credits 2022-2042 655 437 208

Benefit Plans (Tables)

Benefit Plans (Tables)	9 Months Ended
	Sep. 30, 2022
Defined Benefit Plan Disclosure [Line Items]
Net Periodic Benefit Costs	The components of net periodic benefit costs for sponsored defined benefit pension and OPEB plans for the three and nine months ended September 30 are included below (in millions). For IPL and WPL, amounts are for their plan participants covered under plans they sponsor, as well as amounts directly assigned to them related to certain participants in the Alliant Energy and Corporate Services sponsored plans. Defined Benefit Pension Plans OPEB Plans Three Months Nine Months Three Months Nine Months Alliant Energy 2022 2021 2022 2021 2022 2021 2022 2021 Service cost $3 $2 $7 $8 $— $1 $2 $3 Interest cost 9 9 27 26 1 1 4 3 Expected return on plan assets (18) (17) (52) (51) — (1) (3) (3) Amortization of prior service credit — (1) — (1) — — — — Amortization of actuarial loss 8 10 24 29 1 1 2 3 $2 $3 $6 $11 $2 $2 $5 $6 Defined Benefit Pension Plans OPEB Plans Three Months Nine Months Three Months Nine Months IPL 2022 2021 2022 2021 2022 2021 2022 2021 Service cost $1 $1 $4 $5 $— $— $1 $1 Interest cost 4 4 12 12 1 1 2 2 Expected return on plan assets (7) (8) (23) (24) (1) (1) (3) (3) Amortization of actuarial loss 3 5 10 13 — — — 1 $1 $2 $3 $6 $— $— $— $1 Defined Benefit Pension Plans OPEB Plans Three Months Nine Months Three Months Nine Months WPL 2022 2021 2022 2021 2022 2021 2022 2021 Service cost $— $1 $2 $3 $— $1 $— $1 Interest cost 4 3 12 11 1 — 2 1 Expected return on plan assets (7) (8) (23) (23) — — — — Amortization of actuarial loss 4 5 12 14 — 1 1 2 $1 $1 $3 $5 $1 $2 $3 $4
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 for the three and nine months ended September 30 was as follows (in millions): Alliant Energy IPL WPL Three Months Nine Months Three Months Nine Months Three Months Nine Months 2022 2021 2022 2021 2022 2021 2022 2021 2022 2021 2022 2021 Compensation expense $3 $4 $9 $9 $2 $2 $5 $5 $1 $2 $4 $4 Income tax benefits 1 1 3 3 — — 1 1 — — 1 1
Schedule Of Equity-based Compensation Plans Activity	For the nine months ended September 30, 2022, performance shares, performance restricted stock units and restricted stock units were granted to key employees under existing plans as follows. These shares and units will be paid out in shares of common stock, and are therefore accounted for as equity awards. Weighted Average Grants Grant Date Fair Value Performance shares 74,106 $54.45 Performance restricted stock units 84,670 57.01 Restricted stock units 77,122 56.88
IPL [Member]
Defined Benefit Plan Disclosure [Line Items]
Net Periodic Benefit Costs	The components of net periodic benefit costs for sponsored defined benefit pension and OPEB plans for the three and nine months ended September 30 are included below (in millions). For IPL and WPL, amounts are for their plan participants covered under plans they sponsor, as well as amounts directly assigned to them related to certain participants in the Alliant Energy and Corporate Services sponsored plans. Defined Benefit Pension Plans OPEB Plans Three Months Nine Months Three Months Nine Months Alliant Energy 2022 2021 2022 2021 2022 2021 2022 2021 Service cost $3 $2 $7 $8 $— $1 $2 $3 Interest cost 9 9 27 26 1 1 4 3 Expected return on plan assets (18) (17) (52) (51) — (1) (3) (3) Amortization of prior service credit — (1) — (1) — — — — Amortization of actuarial loss 8 10 24 29 1 1 2 3 $2 $3 $6 $11 $2 $2 $5 $6 Defined Benefit Pension Plans OPEB Plans Three Months Nine Months Three Months Nine Months IPL 2022 2021 2022 2021 2022 2021 2022 2021 Service cost $1 $1 $4 $5 $— $— $1 $1 Interest cost 4 4 12 12 1 1 2 2 Expected return on plan assets (7) (8) (23) (24) (1) (1) (3) (3) Amortization of actuarial loss 3 5 10 13 — — — 1 $1 $2 $3 $6 $— $— $— $1 Defined Benefit Pension Plans OPEB Plans Three Months Nine Months Three Months Nine Months WPL 2022 2021 2022 2021 2022 2021 2022 2021 Service cost $— $1 $2 $3 $— $1 $— $1 Interest cost 4 3 12 11 1 — 2 1 Expected return on plan assets (7) (8) (23) (23) — — — — Amortization of actuarial loss 4 5 12 14 — 1 1 2 $1 $1 $3 $5 $1 $2 $3 $4
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 for the three and nine months ended September 30 was as follows (in millions): Alliant Energy IPL WPL Three Months Nine Months Three Months Nine Months Three Months Nine Months 2022 2021 2022 2021 2022 2021 2022 2021 2022 2021 2022 2021 Compensation expense $3 $4 $9 $9 $2 $2 $5 $5 $1 $2 $4 $4 Income tax benefits 1 1 3 3 — — 1 1 — — 1 1
Schedule Of Equity-based Compensation Plans Activity	For the nine months ended September 30, 2022, performance shares, performance restricted stock units and restricted stock units were granted to key employees under existing plans as follows. These shares and units will be paid out in shares of common stock, and are therefore accounted for as equity awards. Weighted Average Grants Grant Date Fair Value Performance shares 74,106 $54.45 Performance restricted stock units 84,670 57.01 Restricted stock units 77,122 56.88
WPL [Member]
Defined Benefit Plan Disclosure [Line Items]
Net Periodic Benefit Costs	The components of net periodic benefit costs for sponsored defined benefit pension and OPEB plans for the three and nine months ended September 30 are included below (in millions). For IPL and WPL, amounts are for their plan participants covered under plans they sponsor, as well as amounts directly assigned to them related to certain participants in the Alliant Energy and Corporate Services sponsored plans. Defined Benefit Pension Plans OPEB Plans Three Months Nine Months Three Months Nine Months Alliant Energy 2022 2021 2022 2021 2022 2021 2022 2021 Service cost $3 $2 $7 $8 $— $1 $2 $3 Interest cost 9 9 27 26 1 1 4 3 Expected return on plan assets (18) (17) (52) (51) — (1) (3) (3) Amortization of prior service credit — (1) — (1) — — — — Amortization of actuarial loss 8 10 24 29 1 1 2 3 $2 $3 $6 $11 $2 $2 $5 $6 Defined Benefit Pension Plans OPEB Plans Three Months Nine Months Three Months Nine Months IPL 2022 2021 2022 2021 2022 2021 2022 2021 Service cost $1 $1 $4 $5 $— $— $1 $1 Interest cost 4 4 12 12 1 1 2 2 Expected return on plan assets (7) (8) (23) (24) (1) (1) (3) (3) Amortization of actuarial loss 3 5 10 13 — — — 1 $1 $2 $3 $6 $— $— $— $1 Defined Benefit Pension Plans OPEB Plans Three Months Nine Months Three Months Nine Months WPL 2022 2021 2022 2021 2022 2021 2022 2021 Service cost $— $1 $2 $3 $— $1 $— $1 Interest cost 4 3 12 11 1 — 2 1 Expected return on plan assets (7) (8) (23) (23) — — — — Amortization of actuarial loss 4 5 12 14 — 1 1 2 $1 $1 $3 $5 $1 $2 $3 $4
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 for the three and nine months ended September 30 was as follows (in millions): Alliant Energy IPL WPL Three Months Nine Months Three Months Nine Months Three Months Nine Months 2022 2021 2022 2021 2022 2021 2022 2021 2022 2021 2022 2021 Compensation expense $3 $4 $9 $9 $2 $2 $5 $5 $1 $2 $4 $4 Income tax benefits 1 1 3 3 — — 1 1 — — 1 1
Schedule Of Equity-based Compensation Plans Activity	For the nine months ended September 30, 2022, performance shares, performance restricted stock units and restricted stock units were granted to key employees under existing plans as follows. These shares and units will be paid out in shares of common stock, and are therefore accounted for as equity awards. Weighted Average Grants Grant Date Fair Value Performance shares 74,106 $54.45 Performance restricted stock units 84,670 57.01 Restricted stock units 77,122 56.88

Derivative Instruments (Tables)

Derivative Instruments (Tables)	9 Months Ended
	Sep. 30, 2022
Derivative Instruments [Line Items]
Notional Amounts Of Derivative Instruments	As of September 30, 2022, gross notional amounts and settlement/delivery years related to outstanding swap contracts, option contracts, physical forward contracts and FTRs that were accounted for as commodity derivative instruments were as follows (units in thousands): Electricity FTRs Natural Gas Coal Diesel Fuel MWhs Years MWhs Years Dths Years Tons Years Gallons Years Alliant Energy 1,379 2022-2024 14,454 2022-2023 249,508 2022-2032 1,566 2022-2023 756 2022 IPL 768 2022-2024 6,165 2022-2023 135,193 2022-2030 669 2022-2023 — — WPL 611 2022-2023 8,289 2022-2023 114,315 2022-2032 897 2022-2023 756 2022
Fair Value Of Financial Instruments	Derivative instruments are recorded at fair value each reporting date on the balance sheets as assets or liabilities as follows (in millions): Alliant Energy IPL WPL September 30, December 31, September 30, December 31, September 30, December 31, Current derivative assets $200 $113 $117 $48 $83 $65 Non-current derivative assets 160 63 85 36 75 27 Current derivative liabilities 71 8 54 4 17 4 Non-current derivative liabilities 27 1 12 — 15 1
Balance Sheet Offsetting	However, if the fair value amounts of derivative instruments by counterparty were netted, derivative assets and derivative liabilities related to commodity contracts would have been presented on the balance sheets as follows (in millions): Alliant Energy IPL WPL Gross Gross Gross (as reported) Net (as reported) Net (as reported) Net September 30, 2022 Derivative assets $360 $308 $202 $165 $158 $143 Derivative liabilities 98 46 66 29 32 17 December 31, 2021 Derivative assets 176 171 84 83 92 88 Derivative liabilities 9 4 4 3 5 1
IPL [Member]
Derivative Instruments [Line Items]
Notional Amounts Of Derivative Instruments	As of September 30, 2022, gross notional amounts and settlement/delivery years related to outstanding swap contracts, option contracts, physical forward contracts and FTRs that were accounted for as commodity derivative instruments were as follows (units in thousands): Electricity FTRs Natural Gas Coal Diesel Fuel MWhs Years MWhs Years Dths Years Tons Years Gallons Years Alliant Energy 1,379 2022-2024 14,454 2022-2023 249,508 2022-2032 1,566 2022-2023 756 2022 IPL 768 2022-2024 6,165 2022-2023 135,193 2022-2030 669 2022-2023 — — WPL 611 2022-2023 8,289 2022-2023 114,315 2022-2032 897 2022-2023 756 2022
Fair Value Of Financial Instruments	Derivative instruments are recorded at fair value each reporting date on the balance sheets as assets or liabilities as follows (in millions): Alliant Energy IPL WPL September 30, December 31, September 30, December 31, September 30, December 31, Current derivative assets $200 $113 $117 $48 $83 $65 Non-current derivative assets 160 63 85 36 75 27 Current derivative liabilities 71 8 54 4 17 4 Non-current derivative liabilities 27 1 12 — 15 1
Balance Sheet Offsetting	However, if the fair value amounts of derivative instruments by counterparty were netted, derivative assets and derivative liabilities related to commodity contracts would have been presented on the balance sheets as follows (in millions): Alliant Energy IPL WPL Gross Gross Gross (as reported) Net (as reported) Net (as reported) Net September 30, 2022 Derivative assets $360 $308 $202 $165 $158 $143 Derivative liabilities 98 46 66 29 32 17 December 31, 2021 Derivative assets 176 171 84 83 92 88 Derivative liabilities 9 4 4 3 5 1
WPL [Member]
Derivative Instruments [Line Items]
Notional Amounts Of Derivative Instruments	As of September 30, 2022, gross notional amounts and settlement/delivery years related to outstanding swap contracts, option contracts, physical forward contracts and FTRs that were accounted for as commodity derivative instruments were as follows (units in thousands): Electricity FTRs Natural Gas Coal Diesel Fuel MWhs Years MWhs Years Dths Years Tons Years Gallons Years Alliant Energy 1,379 2022-2024 14,454 2022-2023 249,508 2022-2032 1,566 2022-2023 756 2022 IPL 768 2022-2024 6,165 2022-2023 135,193 2022-2030 669 2022-2023 — — WPL 611 2022-2023 8,289 2022-2023 114,315 2022-2032 897 2022-2023 756 2022
Fair Value Of Financial Instruments	Derivative instruments are recorded at fair value each reporting date on the balance sheets as assets or liabilities as follows (in millions): Alliant Energy IPL WPL September 30, December 31, September 30, December 31, September 30, December 31, Current derivative assets $200 $113 $117 $48 $83 $65 Non-current derivative assets 160 63 85 36 75 27 Current derivative liabilities 71 8 54 4 17 4 Non-current derivative liabilities 27 1 12 — 15 1
Balance Sheet Offsetting	However, if the fair value amounts of derivative instruments by counterparty were netted, derivative assets and derivative liabilities related to commodity contracts would have been presented on the balance sheets as follows (in millions): Alliant Energy IPL WPL Gross Gross Gross (as reported) Net (as reported) Net (as reported) Net September 30, 2022 Derivative assets $360 $308 $202 $165 $158 $143 Derivative liabilities 98 46 66 29 32 17 December 31, 2021 Derivative assets 176 171 84 83 92 88 Derivative liabilities 9 4 4 3 5 1

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2022
Statement [Line Items]
Fair Value Measurements	Carrying amounts and related estimated fair values of other financial instruments were as follows (in millions): Alliant Energy September 30, 2022 December 31, 2021 Fair Value Fair Value Carrying Level Level Level Carrying Level Level Level Amount 1 2 3 Total Amount 1 2 3 Total Assets: Money market fund investments $334 $334 $— $— $334 $32 $32 $— $— $32 Derivatives 360 — 295 65 360 176 — 146 30 176 Deferred proceeds 248 — — 248 248 214 — — 214 214 Liabilities: Derivatives 98 — 78 20 98 9 — 8 1 9 Long-term debt (incl. current maturities) 8,228 — 7,473 1 7,474 7,368 — 8,329 1 8,330 IPL September 30, 2022 December 31, 2021 Fair Value Fair Value Carrying Level Level Level Carrying Level Level Level Amount 1 2 3 Total Amount 1 2 3 Total Assets: Money market fund investments $39 $39 $— $— $39 $32 $32 $— $— $32 Derivatives 202 — 150 52 202 84 — 65 19 84 Deferred proceeds 248 — — 248 248 214 — — 214 214 Liabilities: Derivatives 66 — 47 19 66 4 — 3 1 4 Long-term debt 3,645 — 3,228 — 3,228 3,643 — 4,124 — 4,124 WPL September 30, 2022 December 31, 2021 Fair Value Fair Value Carrying Level Level Level Carrying Level Level Level Amount 1 2 3 Total Amount 1 2 3 Total Assets: Money market fund investments $295 $295 $— $— $295 $— $— $— $— $— Derivatives 158 — 145 13 158 92 — 81 11 92 Liabilities: Derivatives 32 — 31 1 32 5 — 5 — 5 Long-term debt (incl. current maturities) 3,019 — 2,778 — 2,778 2,429 — 2,862 — 2,862
Fair Value Measurements Using Significant Unobservable Inputs	Information for fair value measurements using significant unobservable inputs (Level 3 inputs) was as follows (in millions): Alliant Energy Commodity Contract Derivative Assets and (Liabilities), net Deferred Proceeds Three Months Ended September 30 2022 2021 2022 2021 Beginning balance, July 1 $72 $39 $244 $154 Total net gains (losses) included in changes in net assets (realized/unrealized) (1) 5 — — Transfers out of Level 3 — (8) — — Settlements (a) (26) (7) 4 10 Ending balance, September 30 $45 $29 $248 $164 The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30 ($1) $5 $— $— Alliant Energy Commodity Contract Derivative Assets and (Liabilities), net Deferred Proceeds Nine Months Ended September 30 2022 2021 2022 2021 Beginning balance, January 1 $29 $29 $214 $188 Total net gains (losses) included in changes in net assets (realized/unrealized) (17) 6 — — Transfers out of Level 3 — (8) — — Purchases 79 21 — — Settlements (a) (46) (19) 34 (24) Ending balance, September 30 $45 $29 $248 $164 The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30 ($17) $6 $— $— IPL Commodity Contract Derivative Assets and (Liabilities), net Deferred Proceeds Three Months Ended September 30 2022 2021 2022 2021 Beginning balance, July 1 $58 $30 $244 $154 Total net gains (losses) included in changes in net assets (realized/unrealized) (6) 2 — — Transfers out of Level 3 — (8) — — Settlements (a) (19) (5) 4 10 Ending balance, September 30 $33 $19 $248 $164 The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30 ($6) $2 $— $— IPL Commodity Contract Derivative Assets and (Liabilities), net Deferred Proceeds Nine Months Ended September 30 2022 2021 2022 2021 Beginning balance, January 1 $18 $26 $214 $188 Total net losses included in changes in net assets (realized/unrealized) (13) — — — Transfers out of Level 3 — (8) — — Purchases 58 16 — — Settlements (a) (30) (15) 34 (24) Ending balance, September 30 $33 $19 $248 $164 The amount of total net losses for the period included in changes in net assets attributable to the change in unrealized losses relating to assets and liabilities held at September 30 ($14) $— $— $— WPL Commodity Contract Derivative Assets and (Liabilities), net Three Months Ended September 30 2022 2021 Beginning balance, July 1 $14 $9 Total net gains included in changes in net assets (realized/unrealized) 5 3 Settlements (7) (2) Ending balance, September 30 $12 $10 The amount of total net gains for the period included in changes in net assets attributable to the change in unrealized gains relating to assets and liabilities held at September 30 $5 $3 WPL Commodity Contract Derivative Assets and (Liabilities), net Nine Months Ended September 30 2022 2021 Beginning balance, January 1 $11 $3 Total net gains (losses) included in changes in net assets (realized/unrealized) (4) 6 Purchases 21 5 Settlements (16) (4) Ending balance, September 30 $12 $10 The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30 ($3) $6 (a) Settlements related to deferred proceeds are due to the change in the carrying amount of receivables sold less the allowance for expected credit losses associated with the receivables sold and cash amounts received from the receivables sold.
Fair Value Of Net Derivative Assets (Liabilities)	The fair value of FTR and natural gas commodity contracts categorized as Level 3 was recognized as net derivative assets (liabilities) as follows (in millions): Alliant Energy IPL WPL Excluding FTRs FTRs Excluding FTRs FTRs Excluding FTRs FTRs September 30, 2022 ($14) $59 ($15) $48 $1 $11 December 31, 2021 9 20 8 10 1 10
IPL [Member]
Statement [Line Items]
Fair Value Measurements	Carrying amounts and related estimated fair values of other financial instruments were as follows (in millions): Alliant Energy September 30, 2022 December 31, 2021 Fair Value Fair Value Carrying Level Level Level Carrying Level Level Level Amount 1 2 3 Total Amount 1 2 3 Total Assets: Money market fund investments $334 $334 $— $— $334 $32 $32 $— $— $32 Derivatives 360 — 295 65 360 176 — 146 30 176 Deferred proceeds 248 — — 248 248 214 — — 214 214 Liabilities: Derivatives 98 — 78 20 98 9 — 8 1 9 Long-term debt (incl. current maturities) 8,228 — 7,473 1 7,474 7,368 — 8,329 1 8,330 IPL September 30, 2022 December 31, 2021 Fair Value Fair Value Carrying Level Level Level Carrying Level Level Level Amount 1 2 3 Total Amount 1 2 3 Total Assets: Money market fund investments $39 $39 $— $— $39 $32 $32 $— $— $32 Derivatives 202 — 150 52 202 84 — 65 19 84 Deferred proceeds 248 — — 248 248 214 — — 214 214 Liabilities: Derivatives 66 — 47 19 66 4 — 3 1 4 Long-term debt 3,645 — 3,228 — 3,228 3,643 — 4,124 — 4,124 WPL September 30, 2022 December 31, 2021 Fair Value Fair Value Carrying Level Level Level Carrying Level Level Level Amount 1 2 3 Total Amount 1 2 3 Total Assets: Money market fund investments $295 $295 $— $— $295 $— $— $— $— $— Derivatives 158 — 145 13 158 92 — 81 11 92 Liabilities: Derivatives 32 — 31 1 32 5 — 5 — 5 Long-term debt (incl. current maturities) 3,019 — 2,778 — 2,778 2,429 — 2,862 — 2,862
Fair Value Measurements Using Significant Unobservable Inputs	Information for fair value measurements using significant unobservable inputs (Level 3 inputs) was as follows (in millions): Alliant Energy Commodity Contract Derivative Assets and (Liabilities), net Deferred Proceeds Three Months Ended September 30 2022 2021 2022 2021 Beginning balance, July 1 $72 $39 $244 $154 Total net gains (losses) included in changes in net assets (realized/unrealized) (1) 5 — — Transfers out of Level 3 — (8) — — Settlements (a) (26) (7) 4 10 Ending balance, September 30 $45 $29 $248 $164 The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30 ($1) $5 $— $— Alliant Energy Commodity Contract Derivative Assets and (Liabilities), net Deferred Proceeds Nine Months Ended September 30 2022 2021 2022 2021 Beginning balance, January 1 $29 $29 $214 $188 Total net gains (losses) included in changes in net assets (realized/unrealized) (17) 6 — — Transfers out of Level 3 — (8) — — Purchases 79 21 — — Settlements (a) (46) (19) 34 (24) Ending balance, September 30 $45 $29 $248 $164 The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30 ($17) $6 $— $— IPL Commodity Contract Derivative Assets and (Liabilities), net Deferred Proceeds Three Months Ended September 30 2022 2021 2022 2021 Beginning balance, July 1 $58 $30 $244 $154 Total net gains (losses) included in changes in net assets (realized/unrealized) (6) 2 — — Transfers out of Level 3 — (8) — — Settlements (a) (19) (5) 4 10 Ending balance, September 30 $33 $19 $248 $164 The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30 ($6) $2 $— $— IPL Commodity Contract Derivative Assets and (Liabilities), net Deferred Proceeds Nine Months Ended September 30 2022 2021 2022 2021 Beginning balance, January 1 $18 $26 $214 $188 Total net losses included in changes in net assets (realized/unrealized) (13) — — — Transfers out of Level 3 — (8) — — Purchases 58 16 — — Settlements (a) (30) (15) 34 (24) Ending balance, September 30 $33 $19 $248 $164 The amount of total net losses for the period included in changes in net assets attributable to the change in unrealized losses relating to assets and liabilities held at September 30 ($14) $— $— $— WPL Commodity Contract Derivative Assets and (Liabilities), net Three Months Ended September 30 2022 2021 Beginning balance, July 1 $14 $9 Total net gains included in changes in net assets (realized/unrealized) 5 3 Settlements (7) (2) Ending balance, September 30 $12 $10 The amount of total net gains for the period included in changes in net assets attributable to the change in unrealized gains relating to assets and liabilities held at September 30 $5 $3 WPL Commodity Contract Derivative Assets and (Liabilities), net Nine Months Ended September 30 2022 2021 Beginning balance, January 1 $11 $3 Total net gains (losses) included in changes in net assets (realized/unrealized) (4) 6 Purchases 21 5 Settlements (16) (4) Ending balance, September 30 $12 $10 The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30 ($3) $6 (a) Settlements related to deferred proceeds are due to the change in the carrying amount of receivables sold less the allowance for expected credit losses associated with the receivables sold and cash amounts received from the receivables sold.
Fair Value Of Net Derivative Assets (Liabilities)	The fair value of FTR and natural gas commodity contracts categorized as Level 3 was recognized as net derivative assets (liabilities) as follows (in millions): Alliant Energy IPL WPL Excluding FTRs FTRs Excluding FTRs FTRs Excluding FTRs FTRs September 30, 2022 ($14) $59 ($15) $48 $1 $11 December 31, 2021 9 20 8 10 1 10
WPL [Member]
Statement [Line Items]
Fair Value Measurements	Carrying amounts and related estimated fair values of other financial instruments were as follows (in millions): Alliant Energy September 30, 2022 December 31, 2021 Fair Value Fair Value Carrying Level Level Level Carrying Level Level Level Amount 1 2 3 Total Amount 1 2 3 Total Assets: Money market fund investments $334 $334 $— $— $334 $32 $32 $— $— $32 Derivatives 360 — 295 65 360 176 — 146 30 176 Deferred proceeds 248 — — 248 248 214 — — 214 214 Liabilities: Derivatives 98 — 78 20 98 9 — 8 1 9 Long-term debt (incl. current maturities) 8,228 — 7,473 1 7,474 7,368 — 8,329 1 8,330 IPL September 30, 2022 December 31, 2021 Fair Value Fair Value Carrying Level Level Level Carrying Level Level Level Amount 1 2 3 Total Amount 1 2 3 Total Assets: Money market fund investments $39 $39 $— $— $39 $32 $32 $— $— $32 Derivatives 202 — 150 52 202 84 — 65 19 84 Deferred proceeds 248 — — 248 248 214 — — 214 214 Liabilities: Derivatives 66 — 47 19 66 4 — 3 1 4 Long-term debt 3,645 — 3,228 — 3,228 3,643 — 4,124 — 4,124 WPL September 30, 2022 December 31, 2021 Fair Value Fair Value Carrying Level Level Level Carrying Level Level Level Amount 1 2 3 Total Amount 1 2 3 Total Assets: Money market fund investments $295 $295 $— $— $295 $— $— $— $— $— Derivatives 158 — 145 13 158 92 — 81 11 92 Liabilities: Derivatives 32 — 31 1 32 5 — 5 — 5 Long-term debt (incl. current maturities) 3,019 — 2,778 — 2,778 2,429 — 2,862 — 2,862
Fair Value Measurements Using Significant Unobservable Inputs	Information for fair value measurements using significant unobservable inputs (Level 3 inputs) was as follows (in millions): Alliant Energy Commodity Contract Derivative Assets and (Liabilities), net Deferred Proceeds Three Months Ended September 30 2022 2021 2022 2021 Beginning balance, July 1 $72 $39 $244 $154 Total net gains (losses) included in changes in net assets (realized/unrealized) (1) 5 — — Transfers out of Level 3 — (8) — — Settlements (a) (26) (7) 4 10 Ending balance, September 30 $45 $29 $248 $164 The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30 ($1) $5 $— $— Alliant Energy Commodity Contract Derivative Assets and (Liabilities), net Deferred Proceeds Nine Months Ended September 30 2022 2021 2022 2021 Beginning balance, January 1 $29 $29 $214 $188 Total net gains (losses) included in changes in net assets (realized/unrealized) (17) 6 — — Transfers out of Level 3 — (8) — — Purchases 79 21 — — Settlements (a) (46) (19) 34 (24) Ending balance, September 30 $45 $29 $248 $164 The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30 ($17) $6 $— $— IPL Commodity Contract Derivative Assets and (Liabilities), net Deferred Proceeds Three Months Ended September 30 2022 2021 2022 2021 Beginning balance, July 1 $58 $30 $244 $154 Total net gains (losses) included in changes in net assets (realized/unrealized) (6) 2 — — Transfers out of Level 3 — (8) — — Settlements (a) (19) (5) 4 10 Ending balance, September 30 $33 $19 $248 $164 The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30 ($6) $2 $— $— IPL Commodity Contract Derivative Assets and (Liabilities), net Deferred Proceeds Nine Months Ended September 30 2022 2021 2022 2021 Beginning balance, January 1 $18 $26 $214 $188 Total net losses included in changes in net assets (realized/unrealized) (13) — — — Transfers out of Level 3 — (8) — — Purchases 58 16 — — Settlements (a) (30) (15) 34 (24) Ending balance, September 30 $33 $19 $248 $164 The amount of total net losses for the period included in changes in net assets attributable to the change in unrealized losses relating to assets and liabilities held at September 30 ($14) $— $— $— WPL Commodity Contract Derivative Assets and (Liabilities), net Three Months Ended September 30 2022 2021 Beginning balance, July 1 $14 $9 Total net gains included in changes in net assets (realized/unrealized) 5 3 Settlements (7) (2) Ending balance, September 30 $12 $10 The amount of total net gains for the period included in changes in net assets attributable to the change in unrealized gains relating to assets and liabilities held at September 30 $5 $3 WPL Commodity Contract Derivative Assets and (Liabilities), net Nine Months Ended September 30 2022 2021 Beginning balance, January 1 $11 $3 Total net gains (losses) included in changes in net assets (realized/unrealized) (4) 6 Purchases 21 5 Settlements (16) (4) Ending balance, September 30 $12 $10 The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30 ($3) $6 (a) Settlements related to deferred proceeds are due to the change in the carrying amount of receivables sold less the allowance for expected credit losses associated with the receivables sold and cash amounts received from the receivables sold.
Fair Value Of Net Derivative Assets (Liabilities)	The fair value of FTR and natural gas commodity contracts categorized as Level 3 was recognized as net derivative assets (liabilities) as follows (in millions): Alliant Energy IPL WPL Excluding FTRs FTRs Excluding FTRs FTRs Excluding FTRs FTRs September 30, 2022 ($14) $59 ($15) $48 $1 $11 December 31, 2021 9 20 8 10 1 10

Commitments And Contingencies (

Commitments And Contingencies (Tables)	9 Months Ended
	Sep. 30, 2022
Commitments and Contingencies [Line Items]
Other Purchase Commitments	At September 30, 2022, related minimum future commitments were as follows (in millions): Alliant Energy IPL WPL Natural gas $1,608 $742 $866 Coal 197 95 102 Other (a) 126 57 28 $1,931 $894 $996 (a) Includes individual commitments incurred during the normal course of business that exceeded $1 million at September 30, 2022.
MGP Site Estimated Future Costs And Recorded Liabilities	At September 30, 2022, estimated future costs expected to be incurred for the investigation, remediation and monitoring of the MGP sites, as well as environmental liabilities recorded on the balance sheets for these sites, which are not discounted, were as follows (in millions). At September 30, 2022, such amounts for WPL were not material. Alliant Energy IPL Range of estimated future costs $9 - $25 $6 - $19 Current and non-current environmental liabilities $12 $8
IPL [Member]
Commitments and Contingencies [Line Items]
Other Purchase Commitments	At September 30, 2022, related minimum future commitments were as follows (in millions): Alliant Energy IPL WPL Natural gas $1,608 $742 $866 Coal 197 95 102 Other (a) 126 57 28 $1,931 $894 $996 (a) Includes individual commitments incurred during the normal course of business that exceeded $1 million at September 30, 2022.
MGP Site Estimated Future Costs And Recorded Liabilities	At September 30, 2022, estimated future costs expected to be incurred for the investigation, remediation and monitoring of the MGP sites, as well as environmental liabilities recorded on the balance sheets for these sites, which are not discounted, were as follows (in millions). At September 30, 2022, such amounts for WPL were not material. Alliant Energy IPL Range of estimated future costs $9 - $25 $6 - $19 Current and non-current environmental liabilities $12 $8
WPL [Member]
Commitments and Contingencies [Line Items]
Other Purchase Commitments	At September 30, 2022, related minimum future commitments were as follows (in millions): Alliant Energy IPL WPL Natural gas $1,608 $742 $866 Coal 197 95 102 Other (a) 126 57 28 $1,931 $894 $996 (a) Includes individual commitments incurred during the normal course of business that exceeded $1 million at September 30, 2022.

Segments Of Business (Tables)

Segments Of Business (Tables)	9 Months Ended
	Sep. 30, 2022
Segment Reporting Information [Line Items]
Schedule Of Segments Of Business	Certain financial information relating to Alliant Energy’s, IPL’s and WPL’s business segments is as follows. Intersegment revenues were not material to their respective operations. Alliant Energy ATC Holdings, Alliant Utility Non-Utility, Energy Electric Gas Other Total Parent and Other Consolidated (in millions) Three Months Ended September 30, 2022 Revenues $1,039 $62 $11 $1,112 $23 $1,135 Operating income (loss) 304 (3) 1 302 7 309 Net income (loss) attributable to Alliant Energy common shareowners 245 (18) 227 Three Months Ended September 30, 2021 Revenues $939 $50 $13 $1,002 $22 $1,024 Operating income (loss) 290 (5) (5) 280 9 289 Net income attributable to Alliant Energy common shareowners 250 6 256 Alliant Energy ATC Holdings, Alliant Utility Non-Utility, Energy Electric Gas Other Total Parent and Other Consolidated (in millions) Nine Months Ended September 30, 2022 Revenues $2,624 $418 $35 $3,077 $70 $3,147 Operating income 680 62 4 746 23 769 Net income attributable to Alliant Energy common shareowners 574 5 579 Nine Months Ended September 30, 2021 Revenues $2,357 $289 $36 $2,682 $60 $2,742 Operating income (loss) 601 42 (4) 639 24 663 Net income attributable to Alliant Energy common shareowners 537 34 571 IPL Electric Gas Other Total (in millions) Three Months Ended September 30, 2022 Revenues $596 $33 $11 $640 Operating income (loss) 174 (3) — 171 Net income available for common stock 154 Three Months Ended September 30, 2021 Revenues $555 $31 $13 $599 Operating income (loss) 186 (3) (3) 180 Net income available for common stock 157 Nine Months Ended September 30, 2022 Revenues $1,438 $224 $34 $1,696 Operating income 353 33 3 389 Net income available for common stock 327 Nine Months Ended September 30, 2021 Revenues $1,343 $165 $35 $1,543 Operating income (loss) 365 30 (1) 394 Net income available for common stock 322 WPL Electric Gas Other Total (in millions) Three Months Ended September 30, 2022 Revenues $443 $29 $— $472 Operating income 130 — 1 131 Net income 91 Three Months Ended September 30, 2021 Revenues $384 $19 $— $403 Operating income (loss) 104 (2) (2) 100 Net income 93 Nine Months Ended September 30, 2022 Revenues $1,186 $194 $1 $1,381 Operating income 327 29 1 357 Net income 247 Nine Months Ended September 30, 2021 Revenues $1,014 $124 $1 $1,139 Operating income (loss) 236 12 (3) 245 Net income 215
IPL [Member]
Segment Reporting Information [Line Items]
Schedule Of Segments Of Business	Certain financial information relating to Alliant Energy’s, IPL’s and WPL’s business segments is as follows. Intersegment revenues were not material to their respective operations. Alliant Energy ATC Holdings, Alliant Utility Non-Utility, Energy Electric Gas Other Total Parent and Other Consolidated (in millions) Three Months Ended September 30, 2022 Revenues $1,039 $62 $11 $1,112 $23 $1,135 Operating income (loss) 304 (3) 1 302 7 309 Net income (loss) attributable to Alliant Energy common shareowners 245 (18) 227 Three Months Ended September 30, 2021 Revenues $939 $50 $13 $1,002 $22 $1,024 Operating income (loss) 290 (5) (5) 280 9 289 Net income attributable to Alliant Energy common shareowners 250 6 256 Alliant Energy ATC Holdings, Alliant Utility Non-Utility, Energy Electric Gas Other Total Parent and Other Consolidated (in millions) Nine Months Ended September 30, 2022 Revenues $2,624 $418 $35 $3,077 $70 $3,147 Operating income 680 62 4 746 23 769 Net income attributable to Alliant Energy common shareowners 574 5 579 Nine Months Ended September 30, 2021 Revenues $2,357 $289 $36 $2,682 $60 $2,742 Operating income (loss) 601 42 (4) 639 24 663 Net income attributable to Alliant Energy common shareowners 537 34 571 IPL Electric Gas Other Total (in millions) Three Months Ended September 30, 2022 Revenues $596 $33 $11 $640 Operating income (loss) 174 (3) — 171 Net income available for common stock 154 Three Months Ended September 30, 2021 Revenues $555 $31 $13 $599 Operating income (loss) 186 (3) (3) 180 Net income available for common stock 157 Nine Months Ended September 30, 2022 Revenues $1,438 $224 $34 $1,696 Operating income 353 33 3 389 Net income available for common stock 327 Nine Months Ended September 30, 2021 Revenues $1,343 $165 $35 $1,543 Operating income (loss) 365 30 (1) 394 Net income available for common stock 322 WPL Electric Gas Other Total (in millions) Three Months Ended September 30, 2022 Revenues $443 $29 $— $472 Operating income 130 — 1 131 Net income 91 Three Months Ended September 30, 2021 Revenues $384 $19 $— $403 Operating income (loss) 104 (2) (2) 100 Net income 93 Nine Months Ended September 30, 2022 Revenues $1,186 $194 $1 $1,381 Operating income 327 29 1 357 Net income 247 Nine Months Ended September 30, 2021 Revenues $1,014 $124 $1 $1,139 Operating income (loss) 236 12 (3) 245 Net income 215
WPL [Member]
Segment Reporting Information [Line Items]
Schedule Of Segments Of Business	Certain financial information relating to Alliant Energy’s, IPL’s and WPL’s business segments is as follows. Intersegment revenues were not material to their respective operations. Alliant Energy ATC Holdings, Alliant Utility Non-Utility, Energy Electric Gas Other Total Parent and Other Consolidated (in millions) Three Months Ended September 30, 2022 Revenues $1,039 $62 $11 $1,112 $23 $1,135 Operating income (loss) 304 (3) 1 302 7 309 Net income (loss) attributable to Alliant Energy common shareowners 245 (18) 227 Three Months Ended September 30, 2021 Revenues $939 $50 $13 $1,002 $22 $1,024 Operating income (loss) 290 (5) (5) 280 9 289 Net income attributable to Alliant Energy common shareowners 250 6 256 Alliant Energy ATC Holdings, Alliant Utility Non-Utility, Energy Electric Gas Other Total Parent and Other Consolidated (in millions) Nine Months Ended September 30, 2022 Revenues $2,624 $418 $35 $3,077 $70 $3,147 Operating income 680 62 4 746 23 769 Net income attributable to Alliant Energy common shareowners 574 5 579 Nine Months Ended September 30, 2021 Revenues $2,357 $289 $36 $2,682 $60 $2,742 Operating income (loss) 601 42 (4) 639 24 663 Net income attributable to Alliant Energy common shareowners 537 34 571 IPL Electric Gas Other Total (in millions) Three Months Ended September 30, 2022 Revenues $596 $33 $11 $640 Operating income (loss) 174 (3) — 171 Net income available for common stock 154 Three Months Ended September 30, 2021 Revenues $555 $31 $13 $599 Operating income (loss) 186 (3) (3) 180 Net income available for common stock 157 Nine Months Ended September 30, 2022 Revenues $1,438 $224 $34 $1,696 Operating income 353 33 3 389 Net income available for common stock 327 Nine Months Ended September 30, 2021 Revenues $1,343 $165 $35 $1,543 Operating income (loss) 365 30 (1) 394 Net income available for common stock 322 WPL Electric Gas Other Total (in millions) Three Months Ended September 30, 2022 Revenues $443 $29 $— $472 Operating income 130 — 1 131 Net income 91 Three Months Ended September 30, 2021 Revenues $384 $19 $— $403 Operating income (loss) 104 (2) (2) 100 Net income 93 Nine Months Ended September 30, 2022 Revenues $1,186 $194 $1 $1,381 Operating income 327 29 1 357 Net income 247 Nine Months Ended September 30, 2021 Revenues $1,014 $124 $1 $1,139 Operating income (loss) 236 12 (3) 245 Net income 215

Related Parties (Tables)

Related Parties (Tables)	9 Months Ended
	Sep. 30, 2022
Related Party Transactions [Line Items]
Services Provided, Sales Credited And Purchases	The amounts billed for services provided, sales credited and purchases for the three and nine months ended September 30 were as follows (in millions): IPL WPL Three Months Nine Months Three Months Nine Months 2022 2021 2022 2021 2022 2021 2022 2021 Corporate Services billings $45 $50 $136 $138 $39 $37 $117 $113 Sales credited 11 4 11 9 31 16 62 23 Purchases billed 119 105 342 347 42 24 103 71
Net Intercompany Payables	Net intercompany payables to Corporate Services were as follows (in millions): IPL WPL September 30, 2022 December 31, 2021 September 30, 2022 December 31, 2021 Net payables to Corporate Services $113 $110 $88 $83
Related Amounts Billed Between Parties	The related amounts billed between the parties for the three and nine months ended September 30 were as follows (in millions): Three Months Nine Months 2022 2021 2022 2021 ATC billings to WPL $38 $29 $107 $91 WPL billings to ATC 6 4 14 13
IPL [Member]
Related Party Transactions [Line Items]
Services Provided, Sales Credited And Purchases	The amounts billed for services provided, sales credited and purchases for the three and nine months ended September 30 were as follows (in millions): IPL WPL Three Months Nine Months Three Months Nine Months 2022 2021 2022 2021 2022 2021 2022 2021 Corporate Services billings $45 $50 $136 $138 $39 $37 $117 $113 Sales credited 11 4 11 9 31 16 62 23 Purchases billed 119 105 342 347 42 24 103 71
Net Intercompany Payables	Net intercompany payables to Corporate Services were as follows (in millions): IPL WPL September 30, 2022 December 31, 2021 September 30, 2022 December 31, 2021 Net payables to Corporate Services $113 $110 $88 $83
WPL [Member]
Related Party Transactions [Line Items]
Services Provided, Sales Credited And Purchases	The amounts billed for services provided, sales credited and purchases for the three and nine months ended September 30 were as follows (in millions): IPL WPL Three Months Nine Months Three Months Nine Months 2022 2021 2022 2021 2022 2021 2022 2021 Corporate Services billings $45 $50 $136 $138 $39 $37 $117 $113 Sales credited 11 4 11 9 31 16 62 23 Purchases billed 119 105 342 347 42 24 103 71
Net Intercompany Payables	Net intercompany payables to Corporate Services were as follows (in millions): IPL WPL September 30, 2022 December 31, 2021 September 30, 2022 December 31, 2021 Net payables to Corporate Services $113 $110 $88 $83
Related Amounts Billed Between Parties	The related amounts billed between the parties for the three and nine months ended September 30 were as follows (in millions): Three Months Nine Months 2022 2021 2022 2021 ATC billings to WPL $38 $29 $107 $91 WPL billings to ATC 6 4 14 13

Summary Of Significant Accoun_3

Summary Of Significant Accounting Policies (Narrative) (Details) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2022 USD ($)	Jun. 30, 2022 USD ($)	Sep. 30, 2022 USD ($)	Sep. 30, 2021 USD ($)	Dec. 31, 2024 MW	Dec. 31, 2021 USD ($)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Money market fund investments	$ 334		$ 334			$ 32
Money market fund investments interest rate, percentage	3%		3%
Distributions to noncontrolling interest			$ 29	$ 0
IPL [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Money market fund investments	$ 39		$ 39			32
Money market fund investments interest rate, percentage	3%		3%
WPL [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Money market fund investments	$ 295		$ 295			$ 0
Money market fund investments interest rate, percentage	3%		3%
WPL's cash contribution		$ 62
Tax equity partner's cash contribution		29
Contributed funds paid to WPL for equity interests		$ 88
Distributions to noncontrolling interest	$ 29		$ 29	$ 0
WPL [Member] | Solar [Member] | Forecast [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Nameplate capacity (in MW) | MW					1,100

Regulatory Matters (Narrative)

Regulatory Matters (Narrative) (Details) - USD ($) $ in Millions	Sep. 30, 2022	Dec. 31, 2021
Regulatory Matters [Line Items]
Regulatory assets	$ 2,041	$ 1,940
IPL [Member]
Regulatory Matters [Line Items]
Regulatory assets	1,423	1,443
WPL [Member]
Regulatory Matters [Line Items]
Regulatory assets	618	$ 497
Deferred Fuel Costs | WPL [Member]
Regulatory Matters [Line Items]
Regulatory assets	$ 83

Regulatory Matters (Regulatory

Regulatory Matters (Regulatory Assets) (Details) - USD ($) $ in Millions	Sep. 30, 2022	Dec. 31, 2021
Regulatory Assets [Line Items]
Regulatory assets	$ 2,041	$ 1,940
Tax-related [Member]
Regulatory Assets [Line Items]
Regulatory assets	913	934
Pension and OPEB costs [Member]
Regulatory Assets [Line Items]
Regulatory assets	436	462
Asset retirement obligations [Member]
Regulatory Assets [Line Items]
Regulatory assets	145	128
Commodity cost recovery [Member]
Regulatory Assets [Line Items]
Regulatory assets	129	42
Derivatives [Member]
Regulatory Assets [Line Items]
Regulatory assets	102	8
Assets retired early [Member]
Regulatory Assets [Line Items]
Regulatory assets	75	92
IPL's DAEC PPA amendment [Member]
Regulatory Assets [Line Items]
Regulatory assets	72	90
WPL's Western Wisconsin gas distribution expansion investments [Member]
Regulatory Assets [Line Items]
Regulatory assets	49	52
Other [Member]
Regulatory Assets [Line Items]
Regulatory assets	120	132
IPL [Member]
Regulatory Assets [Line Items]
Regulatory assets	1,423	1,443
IPL [Member] | Tax-related [Member]
Regulatory Assets [Line Items]
Regulatory assets	842	884
IPL [Member] | Pension and OPEB costs [Member]
Regulatory Assets [Line Items]
Regulatory assets	216	228
IPL [Member] | Asset retirement obligations [Member]
Regulatory Assets [Line Items]
Regulatory assets	104	89
IPL [Member] | Commodity cost recovery [Member]
Regulatory Assets [Line Items]
Regulatory assets	2	2
IPL [Member] | Derivatives [Member]
Regulatory Assets [Line Items]
Regulatory assets	67	4
IPL [Member] | Assets retired early [Member]
Regulatory Assets [Line Items]
Regulatory assets	56	66
IPL [Member] | IPL's DAEC PPA amendment [Member]
Regulatory Assets [Line Items]
Regulatory assets	72	90
IPL [Member] | Other [Member]
Regulatory Assets [Line Items]
Regulatory assets	64	80
WPL [Member]
Regulatory Assets [Line Items]
Regulatory assets	618	497
WPL [Member] | Tax-related [Member]
Regulatory Assets [Line Items]
Regulatory assets	71	50
WPL [Member] | Pension and OPEB costs [Member]
Regulatory Assets [Line Items]
Regulatory assets	220	234
WPL [Member] | Asset retirement obligations [Member]
Regulatory Assets [Line Items]
Regulatory assets	41	39
WPL [Member] | Commodity cost recovery [Member]
Regulatory Assets [Line Items]
Regulatory assets	127	40
WPL [Member] | Derivatives [Member]
Regulatory Assets [Line Items]
Regulatory assets	35	4
WPL [Member] | Assets retired early [Member]
Regulatory Assets [Line Items]
Regulatory assets	19	26
WPL [Member] | WPL's Western Wisconsin gas distribution expansion investments [Member]
Regulatory Assets [Line Items]
Regulatory assets	49	52
WPL [Member] | Other [Member]
Regulatory Assets [Line Items]
Regulatory assets	$ 56	$ 52

Regulatory Matters (Regulator_2

Regulatory Matters (Regulatory Liabilities) (Details) - USD ($) $ in Millions	Sep. 30, 2022	Dec. 31, 2021
Regulatory Liabilities [Line Items]
Regulatory liabilities	$ 1,387	$ 1,271
Tax-related [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	582	585
Cost of removal obligations [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	398	384
Derivatives [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	312	166
WPL's West Riverside liquidated damages [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	33	36
Electric transmission cost recovery [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	16	51
Other [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	46	49
IPL [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	761	691
IPL [Member] | Tax-related [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	304	312
IPL [Member] | Cost of removal obligations [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	258	252
IPL [Member] | Derivatives [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	164	77
IPL [Member] | Electric transmission cost recovery [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	4	27
IPL [Member] | Other [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	31	23
WPL [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	626	580
WPL [Member] | Tax-related [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	278	273
WPL [Member] | Cost of removal obligations [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	140	132
WPL [Member] | Derivatives [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	148	89
WPL [Member] | WPL's West Riverside liquidated damages [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	33	36
WPL [Member] | Electric transmission cost recovery [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	12	24
WPL [Member] | Other [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	$ 15	$ 26

Property, Plant and Equipment (

Property, Plant and Equipment (Narrative) (Details)	9 Months Ended
	Sep. 30, 2022 MW
Edgewater Generating Station | WPL [Member]
Property, Plant and Equipment [Line Items]
Nameplate capacity (in MW)	414
Columbia Energy Center | WPL [Member]
Property, Plant and Equipment [Line Items]
Nameplate capacity (in MW)	595
Lansing Generating Station | IPL [Member]
Property, Plant and Equipment [Line Items]
Nameplate capacity (in MW)	275

Receivables (Narrative) (Detail

Receivables (Narrative) (Details) - Receivables Sold [Member] - IPL [Member] $ in Millions	Sep. 30, 2022 USD ($)
Receivables [Line Items]
Available capacity	$ 109
Financial Asset, Past Due [Member]
Receivables [Line Items]
Outstanding receivables past due	$ 20

Receivables (Maximum And Averag

Receivables (Maximum And Average Outstanding Cash Proceeds) (Details) - IPL [Member] - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Maximum [Member]
Receivables [Line Items]
Maximum outstanding aggregate cash proceeds (based on daily outstanding balances)	$ 36	$ 110	$ 66	$ 110
Average [Member]
Receivables [Line Items]
Average outstanding aggregate cash proceeds (based on daily outstanding balances)	$ 3	$ 65	$ 8	$ 52

Receivables (Receivables Sold U

Receivables (Receivables Sold Under The Agreement) (Details) - USD ($) $ in Millions	Sep. 30, 2022	Dec. 31, 2021
Receivables [Line Items]
Fair value of deferred proceeds	$ 248	$ 214
IPL [Member]
Receivables [Line Items]
Fair value of deferred proceeds	248	214
Receivables Sold [Member] | IPL [Member]
Receivables [Line Items]
Customer accounts receivable	169	125
Unbilled utility revenues	92	104
Receivables sold to third party	261	229
Less: cash proceeds	1	1
Deferred proceeds	260	228
Less: allowance for expected credit losses	12	14
Fair value of deferred proceeds	$ 248	$ 214

Receivables (Additional Attribu

Receivables (Additional Attributes Of Receivables Sold Under The Agreement) (Details) - IPL [Member] - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Receivables [Line Items]
Collections	$ 670	$ 607	$ 1,731	$ 1,589
Write-offs, net of recoveries	$ 3	$ 4	$ 6	$ 7

Investments (Unconsolidated Equ

Investments (Unconsolidated Equity Investments) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Schedule of Equity Method Investments [Line Items]
Equity (income) loss from unconsolidated investments, net	$ (5)	$ (13)	$ (37)	$ (47)
ATC Holdings [Member]
Schedule of Equity Method Investments [Line Items]
Equity (income) loss from unconsolidated investments, net	(7)	(12)	(29)	(34)
Other [Member]
Schedule of Equity Method Investments [Line Items]
Equity (income) loss from unconsolidated investments, net	2	(1)	(8)	(13)
Total [Member]
Schedule of Equity Method Investments [Line Items]
Equity (income) loss from unconsolidated investments, net	$ (5)	$ (13)	$ (37)	$ (47)

Common Equity (Common Share Act

Common Equity (Common Share Activity) (Details)	9 Months Ended
	Sep. 30, 2022 shares
Common Stock Oustanding [Roll Forward]
Shares outstanding, January 1, 2022 (in shares)	250,474,529
Shareowner Direct Plan (in shares)	324,533
Equity-based compensation plans (in shares)	222,768
Shares outstanding, September 30, 2022 (in shares)	251,021,830

Common Equity (Changes in Share

Common Equity (Changes in Shareowners' Equity) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance			$ 5,990
Beginning balance	$ 6,166	$ 6,019	5,990	$ 5,888
Net income attributable to common shareowners	227	256	579	571
Net income	227	259	579	579
Common stock dividends	(106)	(101)	(322)	(304)
Shareowner Direct Plan issuances	6	6	19	22
Equity-based compensation plans and other	1	5	(1)	8
Contributions from noncontrolling interest			29
Distributions to noncontrolling interest	(29)		(29)
Ending balance	6,265		6,265
Ending balance	$ 6,265	$ 6,185	$ 6,265	$ 6,185
Common stock dividends (in dollars per share)	$ 0.4275	$ 0.4025	$ 1.2825	$ 1.2075
Common Stock [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance	$ 3	$ 3	$ 3	$ 2
Shareowner Direct Plan issuances				1
Ending balance	3	3	3	3
Additional Paid-in Capital [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance	2,759	2,722	2,749	2,704
Shareowner Direct Plan issuances	6	6	19	21
Equity-based compensation plans and other	2	5	(1)	8
Ending balance	2,767	2,733	2,767	2,733
Retained Earnings [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance	3,387	3,106	3,250	2,994
Net income attributable to common shareowners	227	256	579	571
Common stock dividends	(106)	(101)	(322)	(304)
Equity-based compensation plans and other			1
Ending balance	3,508	3,261	3,508	3,261
Accumulated Other Comprehensive Loss [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance	0	(1)	0	(1)
Ending balance	0	(1)	0	(1)
Shares in Deferred Compensation Trust [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance	(12)	(11)	(12)	(11)
Equity-based compensation plans and other	(1)		(1)
Ending balance	(13)	(11)	(13)	(11)
Noncontrolling Interest [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance	29		0
Contributions from noncontrolling interest			29
Distributions to noncontrolling interest	(29)		(29)
Ending balance	0		0
Cumulative Preferred Stock [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance		200		200
Ending balance		200		200
IPL [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance			3,769
Beginning balance	3,782	3,979	3,769	3,964
Net income attributable to common shareowners	154	157	327	322
Net income	154	160	327	330
Common stock dividends	(80)	(101)	(240)	(301)
Capital contributions from parent			0	50
Ending balance	3,856		3,856
Ending balance	3,856	4,035	3,856	4,035
IPL [Member] | Common Stock [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance	33	33	33	33
Ending balance	33	33	33	33
IPL [Member] | Additional Paid-in Capital [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance	2,807	2,802	2,807	2,752
Capital contributions from parent				50
Ending balance	2,807	2,802	2,807	2,802
IPL [Member] | Retained Earnings [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance	942	944	929	979
Net income attributable to common shareowners	154	157	327	322
Common stock dividends	(80)	(101)	(240)	(301)
Ending balance	1,016	1,000	1,016	1,000
IPL [Member] | Cumulative Preferred Stock [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance	0	200	0	200
Ending balance	0	200	0	200
WPL [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance			2,823
Beginning balance	3,183	2,725	2,823	2,478
Net income	91	93	247	215
Common stock dividends	(44)	(41)	(133)	(126)
Equity-based compensation plans and other			(1)
Capital contributions from parent	155	35	420	245
Contributions from noncontrolling interest			29
Distributions to noncontrolling interest	(29)		(29)
Ending balance	3,356		3,356
Ending balance	3,356	2,812	3,356	2,812
WPL [Member] | Common Stock [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance	66	66	66	66
Ending balance	66	66	66	66
WPL [Member] | Additional Paid-in Capital [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance	1,968	1,669	1,704	1,459
Equity-based compensation plans and other			(1)
Capital contributions from parent	155	35	420	245
Ending balance	2,123	1,704	2,123	1,704
WPL [Member] | Retained Earnings [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance	1,120	990	1,053	953
Net income	91	93	247	215
Common stock dividends	(44)	(41)	(133)	(126)
Ending balance	1,167	1,042	1,167	1,042
WPL [Member] | Noncontrolling Interest [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance	29	0	0	0
Contributions from noncontrolling interest			29
Distributions to noncontrolling interest	(29)		(29)
Ending balance	$ 0	$ 0	$ 0	$ 0

Debt (Narrative) (Details)

Debt (Narrative) (Details) - USD ($) $ in Millions	Oct. 31, 2022	Sep. 30, 2022	Dec. 31, 2021
Subsequent Event [Member]
Debt [Line Items]
Line of credit facility, current borrowing capacity	$ 1,000
Parent Company [Member] | Subsequent Event [Member]
Debt [Line Items]
Line of credit facility, current borrowing capacity	500
IPL [Member] | Subsequent Event [Member]
Debt [Line Items]
Line of credit facility, current borrowing capacity	200
WPL [Member] | Subsequent Event [Member]
Debt [Line Items]
Line of credit facility, current borrowing capacity	$ 300
Senior Notes [Member] | 3.6% senior notes, due 2032 [Member]
Debt [Line Items]
Long-term debt		$ 350
Interest rate, percent		3.60%
Senior Notes [Member] | 3.45% senior notes, due 2022 [Member] | Corporate Services [Member]
Debt [Line Items]
Long-term debt			$ 75
Interest rate, percent			3.45%
Term Loan Credit Agreement [Member] | Term loan credit agreement through March 2024 [Member]
Debt [Line Items]
Long-term debt		$ 300
Interest rate, percent		3%
Term Loan Credit Agreement [Member] | Term loan credit agreement through March 2022 [Member]
Debt [Line Items]
Long-term debt			$ 300
Debentures [Member] | 3.95% debenture, due 2032 [Member] | WPL [Member]
Debt [Line Items]
Long-term debt		$ 600
Interest rate, percent		3.95%

Debt (Credit Facilities) (Detai

Debt (Credit Facilities) (Details) $ in Millions	Sep. 30, 2022 USD ($)
Debt [Line Items]
Amount outstanding	$ 383
Weighted average interest rates	3.40%
Available credit facility capacity	$ 617
IPL [Member]
Debt [Line Items]
Amount outstanding	0
Available credit facility capacity	250
WPL [Member]
Debt [Line Items]
Amount outstanding	0
Available credit facility capacity	$ 300

Debt (Other Short-Term Borrowin

Debt (Other Short-Term Borrowings) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Debt [Line Items]
Maximum amount outstanding (based on daily outstanding balances)	$ 449	$ 648	$ 577	$ 648
Average amount outstanding (based on daily outstanding balances)	$ 353	$ 560	$ 377	$ 479
Weighted average interest rates	2.40%	0.20%	1.20%	0.20%
IPL [Member]
Debt [Line Items]
Maximum amount outstanding (based on daily outstanding balances)	$ 0	$ 8	$ 0	$ 19
Average amount outstanding (based on daily outstanding balances)	$ 0	$ 0	$ 0	$ 0
Weighted average interest rates	0%	0.20%	0%	0.20%
WPL [Member]
Debt [Line Items]
Maximum amount outstanding (based on daily outstanding balances)	$ 251	$ 320	$ 252	$ 320
Average amount outstanding (based on daily outstanding balances)	$ 110	$ 221	$ 160	$ 196
Weighted average interest rates	2%	0.10%	0.90%	0.10%

Revenue (Disaggregation of Reve

Revenue (Disaggregation of Revenues) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 1,135	$ 1,024	$ 3,147	$ 2,742
Electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	1,039	939	2,624	2,357
Electric [Member] | Retail - residential [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	376	348	956	868
Electric [Member] | Retail - commercial [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	243	232	628	579
Electric [Member] | Retail - industrial [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	289	265	743	677
Electric [Member] | Wholesale [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	68	55	168	142
Electric [Member] | Other [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	63	39	129	91
Gas [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	62	50	418	289
Gas [Member] | Retail - residential [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	28	24	237	162
Gas [Member] | Retail - commercial [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	18	13	127	85
Gas [Member] | Retail - industrial [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	4	3	15	11
Gas [Member] | Other [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	12	10	39	31
Other Utility [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	11	13	35	36
Other Utility [Member] | Steam [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	9	9	29	27
Other Utility [Member] | Other [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	2	4	6	9
Non-utility and Other [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	23	22	70	60
Non-utility and Other [Member] | Other [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	23	22	70	60
IPL [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	640	599	1,696	1,543
IPL [Member] | Electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	596	555	1,438	1,343
IPL [Member] | Electric [Member] | Retail - residential [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	222	207	529	488
IPL [Member] | Electric [Member] | Retail - commercial [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	165	160	411	385
IPL [Member] | Electric [Member] | Retail - industrial [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	172	158	418	386
IPL [Member] | Electric [Member] | Wholesale [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	19	18	49	44
IPL [Member] | Electric [Member] | Other [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	18	12	31	40
IPL [Member] | Gas [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	33	31	224	165
IPL [Member] | Gas [Member] | Retail - residential [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	14	14	127	90
IPL [Member] | Gas [Member] | Retail - commercial [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	8	8	62	47
IPL [Member] | Gas [Member] | Retail - industrial [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	3	3	10	8
IPL [Member] | Gas [Member] | Other [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	8	6	25	20
IPL [Member] | Other Utility [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	11	13	34	35
IPL [Member] | Other Utility [Member] | Steam [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	9	9	29	27
IPL [Member] | Other Utility [Member] | Other [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	2	4	5	8
WPL [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	472	403	1,381	1,139
WPL [Member] | Electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	443	384	1,186	1,014
WPL [Member] | Electric [Member] | Retail - residential [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	154	141	427	380
WPL [Member] | Electric [Member] | Retail - commercial [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	78	72	217	194
WPL [Member] | Electric [Member] | Retail - industrial [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	117	107	325	291
WPL [Member] | Electric [Member] | Wholesale [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	49	37	119	98
WPL [Member] | Electric [Member] | Other [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	45	27	98	51
WPL [Member] | Gas [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	29	19	194	124
WPL [Member] | Gas [Member] | Retail - residential [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	14	10	110	72
WPL [Member] | Gas [Member] | Retail - commercial [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	10	5	65	38
WPL [Member] | Gas [Member] | Retail - industrial [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	1	0	5	3
WPL [Member] | Gas [Member] | Other [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	4	4	14	11
WPL [Member] | Other Utility [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0	1	1
WPL [Member] | Other Utility [Member] | Other [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 0	$ 0	$ 1	$ 1

Income Taxes (Narrative) (Detai

Income Taxes (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2024	Dec. 31, 2023
Income Taxes [Line Items]
State income tax rate, percent			9.80%
Regulatory assets			$ (102)	$ (21)
Income tax expense (benefit)	$ 14	$ (21)	26	(66)
Tax-related [Member]
Income Taxes [Line Items]
Regulatory assets	76
Income tax expense (benefit)	8
Forecast [Member]
Income Taxes [Line Items]
State income tax rate, percent					5.50%	8.40%
IPL [Member]
Income Taxes [Line Items]
Regulatory assets			18	(33)
Income tax expense (benefit)	(16)	(12)	(39)	(34)
IPL [Member] | Tax-related [Member]
Income Taxes [Line Items]
Regulatory assets	76
WPL [Member]
Income Taxes [Line Items]
Regulatory assets			(120)	11
Income tax expense (benefit)	$ 16	$ (15)	$ 50	$ (41)

Income Taxes (Schedule Of Effec

Income Taxes (Schedule Of Effective Income Tax Rates) (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Effective Tax Rate [Line Items]
Overall income tax rate	6%	(9.00%)	4%	(13.00%)
IPL [Member]
Effective Tax Rate [Line Items]
Overall income tax rate	(12.00%)	(8.00%)	(14.00%)	(11.00%)
WPL [Member]
Effective Tax Rate [Line Items]
Overall income tax rate	15%	(19.00%)	17%	(24.00%)

Income Taxes (Summary Of Tax Cr

Income Taxes (Summary Of Tax Credit Carryforwards) (Details) $ in Millions	Sep. 30, 2022 USD ($)
State [Member]
Carryforwards [Line Items]
Net operating losses, carryforward amount	$ 500
Federal [Member]
Carryforwards [Line Items]
Tax credits, carryforward amount	655
IPL [Member] | State [Member]
Carryforwards [Line Items]
Net operating losses, carryforward amount	9
IPL [Member] | Federal [Member]
Carryforwards [Line Items]
Tax credits, carryforward amount	437
WPL [Member] | State [Member]
Carryforwards [Line Items]
Net operating losses, carryforward amount	2
WPL [Member] | Federal [Member]
Carryforwards [Line Items]
Tax credits, carryforward amount	$ 208

Benefit Plans (Narrative) (Deta

Benefit Plans (Narrative) (Details) $ in Millions	9 Months Ended
	Sep. 30, 2022 USD ($) shares
Defined Benefit Plan Disclosure [Line Items]
Unrecognized compensation cost	$ 8
Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Unrecognized compensation cost recognized over a weighted average period	1 year
Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Unrecognized compensation cost recognized over a weighted average period	2 years
IPL [Member]
Defined Benefit Plan Disclosure [Line Items]
Unrecognized compensation cost	$ 5
WPL [Member]
Defined Benefit Plan Disclosure [Line Items]
Unrecognized compensation cost	$ 3
Omnibus Incentive Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Shares included in diluted earnings per share (in shares) | shares	285,909

Benefit Plans (Defined Benefit

Benefit Plans (Defined Benefit Pension And Other Postretirement Benefits Plans) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Defined benefit pension plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 3	$ 2	$ 7	$ 8
Interest cost	9	9	27	26
Expected return on plan assets	(18)	(17)	(52)	(51)
Amortization of prior service credit	0	(1)	0	(1)
Amortization of actuarial loss	8	10	24	29
Total	2	3	6	11
OPEB Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	1	2	3
Interest cost	1	1	4	3
Expected return on plan assets	0	(1)	(3)	(3)
Amortization of prior service credit	0	0	0	0
Amortization of actuarial loss	1	1	2	3
Total	2	2	5	6
IPL [Member] | Defined benefit pension plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	1	1	4	5
Interest cost	4	4	12	12
Expected return on plan assets	(7)	(8)	(23)	(24)
Amortization of actuarial loss	3	5	10	13
Total	1	2	3	6
IPL [Member] | OPEB Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	0	1	1
Interest cost	1	1	2	2
Expected return on plan assets	(1)	(1)	(3)	(3)
Amortization of actuarial loss	0	0	0	1
Total	0	0	0	1
WPL [Member] | Defined benefit pension plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	1	2	3
Interest cost	4	3	12	11
Expected return on plan assets	(7)	(8)	(23)	(23)
Amortization of actuarial loss	4	5	12	14
Total	1	1	3	5
WPL [Member] | OPEB Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	1	0	1
Interest cost	1	0	2	1
Expected return on plan assets	0	0	0	0
Amortization of actuarial loss	0	1	1	2
Total	$ 1	$ 2	$ 3	$ 4

Benefit Plans (Recognized Compe

Benefit Plans (Recognized Compensation Expense And Income Tax Benefits) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Compensation expense	$ 3	$ 4	$ 9	$ 9
Income tax benefits	1	1	3	3
IPL [Member]
Compensation expense	2	2	5	5
Income tax benefits	0	0	1	1
WPL [Member]
Compensation expense	1	2	4	4
Income tax benefits	$ 0	$ 0	$ 1	$ 1

Benefit Plans (Summary Of Equit

Benefit Plans (Summary Of Equity-based Compensation Plans Grants) (Details)	9 Months Ended
	Sep. 30, 2022 $ / shares shares
Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grants (in shares/units) | shares	74,106
Weighted average grant date fair value (in dollars per share/unit) | $ / shares	$ 54.45
Performance Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grants (in shares/units) | shares	84,670
Weighted average grant date fair value (in dollars per share/unit) | $ / shares	$ 57.01
Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grants (in shares/units) | shares	77,122
Weighted average grant date fair value (in dollars per share/unit) | $ / shares	$ 56.88

Derivative Instruments (Notiona

Derivative Instruments (Notional Amounts Of Derivative Instruments) (Details) - Commodity [Member] gal in Thousands, T in Thousands, MWh in Thousands, Dekatherms in Thousands	9 Months Ended
	Sep. 30, 2022 Dekatherms MWh T gal
Electricity (MWhs) [Member]
Notional Amount of Derivatives [Line Items]
Notional unit amount of derivatives (in MWhs)	1,379
Electricity (MWhs) [Member] | IPL [Member]
Notional Amount of Derivatives [Line Items]
Notional unit amount of derivatives (in MWhs)	768
Electricity (MWhs) [Member] | WPL [Member]
Notional Amount of Derivatives [Line Items]
Notional unit amount of derivatives (in MWhs)	611
FTRs (MWhs) [Member]
Notional Amount of Derivatives [Line Items]
Notional unit amount of derivatives (in MWhs)	14,454
FTRs (MWhs) [Member] | IPL [Member]
Notional Amount of Derivatives [Line Items]
Notional unit amount of derivatives (in MWhs)	6,165
FTRs (MWhs) [Member] | WPL [Member]
Notional Amount of Derivatives [Line Items]
Notional unit amount of derivatives (in MWhs)	8,289
Natural Gas (Dths) [Member]
Notional Amount of Derivatives [Line Items]
Notional unit amount of derivatives (in Dths) | Dekatherms	249,508
Natural Gas (Dths) [Member] | IPL [Member]
Notional Amount of Derivatives [Line Items]
Notional unit amount of derivatives (in Dths) | Dekatherms	135,193
Natural Gas (Dths) [Member] | WPL [Member]
Notional Amount of Derivatives [Line Items]
Notional unit amount of derivatives (in Dths) | Dekatherms	114,315
Coal (Tons) [Member]
Notional Amount of Derivatives [Line Items]
Notional unit amount of derivatives (in Tons) | T	1,566
Coal (Tons) [Member] | IPL [Member]
Notional Amount of Derivatives [Line Items]
Notional unit amount of derivatives (in Tons) | T	669
Coal (Tons) [Member] | WPL [Member]
Notional Amount of Derivatives [Line Items]
Notional unit amount of derivatives (in Tons) | T	897
Diesel Fuel (Gallons) [Member]
Notional Amount of Derivatives [Line Items]
Notional unit amount of derivatives (in Gallons) | gal	756
Diesel Fuel (Gallons) [Member] | IPL [Member]
Notional Amount of Derivatives [Line Items]
Notional unit amount of derivatives (in Gallons) | gal	0
Diesel Fuel (Gallons) [Member] | WPL [Member]
Notional Amount of Derivatives [Line Items]
Notional unit amount of derivatives (in Gallons) | gal	756

Derivative Instruments (Fair Va

Derivative Instruments (Fair Value Of Financial Instruments) (Details) - Commodity Contracts [Member] - USD ($) $ in Millions	Sep. 30, 2022	Dec. 31, 2021
Derivatives, Fair Value [Line Items]
Current derivative assets	$ 200	$ 113
Non-current derivative assets	160	63
Current derivative liabilities	71	8
Non-current derivative liabilities	27	1
IPL [Member]
Derivatives, Fair Value [Line Items]
Current derivative assets	117	48
Non-current derivative assets	85	36
Current derivative liabilities	54	4
Non-current derivative liabilities	12	0
WPL [Member]
Derivatives, Fair Value [Line Items]
Current derivative assets	83	65
Non-current derivative assets	75	27
Current derivative liabilities	17	4
Non-current derivative liabilities	$ 15	$ 1

Derivative Instruments (Balance

Derivative Instruments (Balance Sheet Offsetting) (Details) - Commodity Contracts [Member] - USD ($) $ in Millions	Sep. 30, 2022	Dec. 31, 2021
Derivative Instruments [Line Items]
Derivative assets, Gross (as reported)	$ 360	$ 176
Derivative assets, Net	308	171
Derivative liabilities, Gross (as reported)	98	9
Derivative liabilities, Net	46	4
IPL [Member]
Derivative Instruments [Line Items]
Derivative assets, Gross (as reported)	202	84
Derivative assets, Net	165	83
Derivative liabilities, Gross (as reported)	66	4
Derivative liabilities, Net	29	3
WPL [Member]
Derivative Instruments [Line Items]
Derivative assets, Gross (as reported)	158	92
Derivative assets, Net	143	88
Derivative liabilities, Gross (as reported)	32	5
Derivative liabilities, Net	$ 17	$ 1

Fair Value Measurements (Fair V

Fair Value Measurements (Fair Value Measurements) (Details) - USD ($) $ in Millions	Sep. 30, 2022	Dec. 31, 2021
Assets:
Money market fund investments	$ 334	$ 32
Deferred proceeds	248	214
Liabilities:
Long-term debt (incl. current maturities)	7,474	8,330
IPL [Member]
Assets:
Money market fund investments	39	32
Deferred proceeds	248	214
Liabilities:
Long-term debt (incl. current maturities)	3,228	4,124
WPL [Member]
Assets:
Money market fund investments	295	0
Liabilities:
Long-term debt (incl. current maturities)	2,778	2,862
Commodity Contracts [Member]
Assets:
Derivatives	360	176
Liabilities:
Derivatives	98	9
Commodity Contracts [Member] | IPL [Member]
Assets:
Derivatives	202	84
Liabilities:
Derivatives	66	4
Commodity Contracts [Member] | WPL [Member]
Assets:
Derivatives	158	92
Liabilities:
Derivatives	32	5
Level 1 [Member]
Assets:
Money market fund investments	334	32
Deferred proceeds	0	0
Liabilities:
Long-term debt (incl. current maturities)	0	0
Level 1 [Member] | IPL [Member]
Assets:
Money market fund investments	39	32
Deferred proceeds	0	0
Liabilities:
Long-term debt (incl. current maturities)	0	0
Level 1 [Member] | WPL [Member]
Assets:
Money market fund investments	295	0
Liabilities:
Long-term debt (incl. current maturities)	0	0
Level 1 [Member] | Commodity Contracts [Member]
Assets:
Derivatives	0	0
Liabilities:
Derivatives	0	0
Level 1 [Member] | Commodity Contracts [Member] | IPL [Member]
Assets:
Derivatives	0	0
Liabilities:
Derivatives	0	0
Level 1 [Member] | Commodity Contracts [Member] | WPL [Member]
Assets:
Derivatives	0	0
Liabilities:
Derivatives	0	0
Level 2 [Member]
Assets:
Money market fund investments	0	0
Deferred proceeds	0	0
Liabilities:
Long-term debt (incl. current maturities)	7,473	8,329
Level 2 [Member] | IPL [Member]
Assets:
Money market fund investments	0	0
Deferred proceeds	0	0
Liabilities:
Long-term debt (incl. current maturities)	3,228	4,124
Level 2 [Member] | WPL [Member]
Assets:
Money market fund investments	0	0
Liabilities:
Long-term debt (incl. current maturities)	2,778	2,862
Level 2 [Member] | Commodity Contracts [Member]
Assets:
Derivatives	295	146
Liabilities:
Derivatives	78	8
Level 2 [Member] | Commodity Contracts [Member] | IPL [Member]
Assets:
Derivatives	150	65
Liabilities:
Derivatives	47	3
Level 2 [Member] | Commodity Contracts [Member] | WPL [Member]
Assets:
Derivatives	145	81
Liabilities:
Derivatives	31	5
Level 3 [Member]
Assets:
Money market fund investments	0	0
Deferred proceeds	248	214
Liabilities:
Long-term debt (incl. current maturities)	1	1
Level 3 [Member] | IPL [Member]
Assets:
Money market fund investments	0	0
Deferred proceeds	248	214
Liabilities:
Long-term debt (incl. current maturities)	0	0
Level 3 [Member] | WPL [Member]
Assets:
Money market fund investments	0	0
Liabilities:
Long-term debt (incl. current maturities)	0	0
Level 3 [Member] | Commodity Contracts [Member]
Assets:
Derivatives	65	30
Liabilities:
Derivatives	20	1
Level 3 [Member] | Commodity Contracts [Member] | IPL [Member]
Assets:
Derivatives	52	19
Liabilities:
Derivatives	19	1
Level 3 [Member] | Commodity Contracts [Member] | WPL [Member]
Assets:
Derivatives	13	11
Liabilities:
Derivatives	1	0
Carrying Amount [Member]
Assets:
Money market fund investments	334	32
Deferred proceeds	248	214
Liabilities:
Long-term debt (incl. current maturities)	8,228	7,368
Carrying Amount [Member] | IPL [Member]
Assets:
Money market fund investments	39	32
Deferred proceeds	248	214
Liabilities:
Long-term debt (incl. current maturities)	3,645	3,643
Carrying Amount [Member] | WPL [Member]
Assets:
Money market fund investments	295	0
Liabilities:
Long-term debt (incl. current maturities)	3,019	2,429
Carrying Amount [Member] | Commodity Contracts [Member]
Assets:
Derivatives	360	176
Liabilities:
Derivatives	98	9
Carrying Amount [Member] | Commodity Contracts [Member] | IPL [Member]
Assets:
Derivatives	202	84
Liabilities:
Derivatives	66	4
Carrying Amount [Member] | Commodity Contracts [Member] | WPL [Member]
Assets:
Derivatives	158	92
Liabilities:
Derivatives	$ 32	$ 5

Fair Value Measurements (Fair_2

Fair Value Measurements (Fair Value Measurements Using Significant Unobservable Inputs) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Commodity Contracts [Member]
Fair Value, Assets and Liabilities, Net, Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	$ 72	$ 39	$ 29	$ 29
Total net gains (losses) included in changes in net assets (realized/unrealized)	(1)	5	(17)	6
Transfers out of Level 3	0	(8)	0	(8)
Purchases			79	21
Settlements	(26)	(7)	(46)	(19)
Ending balance	45	29	45	29
The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30	(1)	5	(17)	6
Commodity Contracts [Member] | IPL [Member]
Fair Value, Assets and Liabilities, Net, Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	58	30	18	26
Total net gains (losses) included in changes in net assets (realized/unrealized)	(6)	2	(13)	0
Transfers out of Level 3	0	(8)	0	(8)
Purchases			58	16
Settlements	(19)	(5)	(30)	(15)
Ending balance	33	19	33	19
The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30	(6)	2	(14)	0
Commodity Contracts [Member] | WPL [Member]
Fair Value, Assets and Liabilities, Net, Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	14	9	11	3
Total net gains (losses) included in changes in net assets (realized/unrealized)	5	3	(4)	6
Purchases			21	5
Settlements	(7)	(2)	(16)	(4)
Ending balance	12	10	12	10
The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30	5	3	(3)	6
Deferred Proceeds [Member]
Fair Value, Assets and Liabilities, Net, Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	244	154	214	188
Total net gains (losses) included in changes in net assets (realized/unrealized)	0	0	0	0
Transfers out of Level 3	0	0	0	0
Purchases			0	0
Settlements	4	10	34	(24)
Ending balance	248	164	248	164
The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30	0	0	0	0
Deferred Proceeds [Member] | IPL [Member]
Fair Value, Assets and Liabilities, Net, Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	244	154	214	188
Total net gains (losses) included in changes in net assets (realized/unrealized)	0	0	0	0
Transfers out of Level 3	0	0	0	0
Purchases			0	0
Settlements	4	10	34	(24)
Ending balance	248	164	248	164
The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30	$ 0	$ 0	$ 0	$ 0

Fair Value Measurements (Fair_3

Fair Value Measurements (Fair Value Of Net Derivative Assets (Liabilities)) (Details) - Commodity Contracts [Member] - USD ($) $ in Millions	Sep. 30, 2022	Jun. 30, 2022	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Dec. 31, 2020
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value, net derivative assets	$ 45	$ 72	$ 29	$ 29	$ 39	$ 29
Excluding Financial Transmission Rights [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value, net derivative liabilities	(14)
Fair value, net derivative assets			9
Financial Transmission Rights [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value, net derivative assets	59		20
IPL [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value, net derivative assets	33	58	18	19	30	26
IPL [Member] | Excluding Financial Transmission Rights [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value, net derivative liabilities	(15)
Fair value, net derivative assets			8
IPL [Member] | Financial Transmission Rights [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value, net derivative assets	48		10
WPL [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value, net derivative assets	12	$ 14	11	$ 10	$ 9	$ 3
WPL [Member] | Excluding Financial Transmission Rights [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value, net derivative assets	1		1
WPL [Member] | Financial Transmission Rights [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value, net derivative assets	$ 11		$ 10

Commitments And Contingencies_2

Commitments And Contingencies (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2020	Dec. 31, 2019
Commitments and Contingencies [Line Items]
Minimum future commitments			$ 1,931
Equity (income) loss from unconsolidated investments, net	$ 5	$ 13	37	$ 47
IPL [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments			894
WPL [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments			996
Capital Purchase Commitment [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments			208
Capital Purchase Commitment [Member] | WPL [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments			206
Indemnification Agreement [Member]
Commitments and Contingencies [Line Items]
Obligations, maximum	59		59
Indemnification Agreement [Member] | Purchased Power [Member]
Commitments and Contingencies [Line Items]
Obligations, maximum	17		$ 17
Whiting Petroleum Affiliate [Member]
Commitments and Contingencies [Line Items]
Partnership share, percent			6%
Obligations, maximum	58		$ 58
Credit loss liability	5		5
Federal Energy Regulatory Commission [Member]
Commitments and Contingencies [Line Items]
MISO base return on equity, percentage					10.02%	9.88%
Equity (income) loss from unconsolidated investments, net	$ 5		$ 5

Commitments And Contingencies_3

Commitments And Contingencies (Other Purchase Commitments) (Details) $ in Millions	9 Months Ended
	Sep. 30, 2022 USD ($)
Commitments and Contingencies [Line Items]
Minimum future commitments	$ 1,931
Individual commitments incurred	1
IPL [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	894
Individual commitments incurred	1
WPL [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	996
Individual commitments incurred	1
Natural gas [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	1,608
Natural gas [Member] | IPL [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	742
Natural gas [Member] | WPL [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	866
Coal [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	197
Coal [Member] | IPL [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	95
Coal [Member] | WPL [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	102
Other [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	126
Other [Member] | IPL [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	57
Other [Member] | WPL [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	$ 28

Commitments And Contingencies_4

Commitments And Contingencies (MPG Site Estimated Future Costs And Recorded Liabilities) (Details) - Natural Gas Processing Plant [Member] $ in Millions	9 Months Ended
	Sep. 30, 2022 USD ($)
Commitments and Contingencies [Line Items]
Current and non-current environmental liabilities	$ 12
IPL [Member]
Commitments and Contingencies [Line Items]
Current and non-current environmental liabilities	8
Minimum [Member]
Commitments and Contingencies [Line Items]
Range of estimated future costs	9
Minimum [Member] | IPL [Member]
Commitments and Contingencies [Line Items]
Range of estimated future costs	6
Maximum [Member]
Commitments and Contingencies [Line Items]
Range of estimated future costs	25
Maximum [Member] | IPL [Member]
Commitments and Contingencies [Line Items]
Range of estimated future costs	$ 19

Segments Of Business (Schedule

Segments Of Business (Schedule Of Segments Of Business) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Segment Reporting Information [Line Items]
Revenues	$ 1,135	$ 1,024	$ 3,147	$ 2,742
Operating income (loss)	309	289	769	663
Net income (loss) attributable to common shareowners	227	256	579	571
Net income	227	259	579	579
IPL [Member]
Segment Reporting Information [Line Items]
Revenues	640	599	1,696	1,543
Operating income (loss)	171	180	389	394
Net income (loss) attributable to common shareowners	154	157	327	322
Net income	154	160	327	330
WPL [Member]
Segment Reporting Information [Line Items]
Revenues	472	403	1,381	1,139
Operating income (loss)	131	100	357	245
Net income	91	93	247	215
Electric [Member]
Segment Reporting Information [Line Items]
Revenues	1,039	939	2,624	2,357
Operating income (loss)	304	290	680	601
Electric [Member] | IPL [Member]
Segment Reporting Information [Line Items]
Revenues	596	555	1,438	1,343
Operating income (loss)	174	186	353	365
Electric [Member] | WPL [Member]
Segment Reporting Information [Line Items]
Revenues	443	384	1,186	1,014
Operating income (loss)	130	104	327	236
Gas [Member]
Segment Reporting Information [Line Items]
Revenues	62	50	418	289
Operating income (loss)	(3)	(5)	62	42
Gas [Member] | IPL [Member]
Segment Reporting Information [Line Items]
Revenues	33	31	224	165
Operating income (loss)	(3)	(3)	33	30
Gas [Member] | WPL [Member]
Segment Reporting Information [Line Items]
Revenues	29	19	194	124
Operating income (loss)	0	(2)	29	12
Other Utility [Member]
Segment Reporting Information [Line Items]
Revenues	11	13	35	36
Operating income (loss)	1	(5)	4	(4)
Other Utility [Member] | IPL [Member]
Segment Reporting Information [Line Items]
Revenues	11	13	34	35
Operating income (loss)	0	(3)	3	(1)
Other Utility [Member] | WPL [Member]
Segment Reporting Information [Line Items]
Revenues	0	0	1	1
Operating income (loss)	1	(2)	1	(3)
Utility Business [Member]
Segment Reporting Information [Line Items]
Revenues	1,112	1,002	3,077	2,682
Operating income (loss)	302	280	746	639
Net income (loss) attributable to common shareowners	245	250	574	537
ATC Holdings, Non-Utility, Parent and Other [Member]
Segment Reporting Information [Line Items]
Revenues	23	22	70	60
Operating income (loss)	7	9	23	24
Net income (loss) attributable to common shareowners	$ (18)	$ 6	$ 5	$ 34

Related Parties (Narrative) (De

Related Parties (Narrative) (Details) - USD ($) $ in Millions	Sep. 30, 2022	Dec. 31, 2021
WPL [Member] | WPL Owed ATC LLC [Member]
Related Party Transactions [Line Items]
Net amounts owed	$ 9	$ 10

Related Parties (Service Agreem

Related Parties (Service Agreements) (Details) - Corporate Services [Member] - Subsidiary of Common Parent [Member] - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Corporate Services Billings [Member] | IPL [Member]
Related Party Transactions [Line Items]
Amounts billed between related parties	$ 45	$ 50	$ 136	$ 138
Corporate Services Billings [Member] | WPL [Member]
Related Party Transactions [Line Items]
Amounts billed between related parties	39	37	117	113
Sales Credited [Member] | IPL [Member]
Related Party Transactions [Line Items]
Amounts billed between related parties	11	4	11	9
Sales Credited [Member] | WPL [Member]
Related Party Transactions [Line Items]
Amounts billed between related parties	31	16	62	23
Purchases Billed [Member] | IPL [Member]
Related Party Transactions [Line Items]
Amounts billed between related parties	119	105	342	347
Purchases Billed [Member] | WPL [Member]
Related Party Transactions [Line Items]
Amounts billed between related parties	$ 42	$ 24	$ 103	$ 71

Related Parties (Net Intercompa

Related Parties (Net Intercompany Payables) (Details) - Subsidiary of Common Parent [Member] - Corporate Services [Member] - USD ($) $ in Millions	Sep. 30, 2022	Dec. 31, 2021
IPL [Member]
Related Party Transactions [Line Items]
Net amounts owed	$ 113	$ 110
WPL [Member]
Related Party Transactions [Line Items]
Net amounts owed	$ 88	$ 83

Related Parties (Amounts Billed

Related Parties (Amounts Billed Between Parties) (Details) - ATC LLC [Member] - WPL [Member] - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
ATC Billings To WPL [Member]
Related Party Transactions [Line Items]
Amounts billed between related parties	$ 38	$ 29	$ 107	$ 91
WPL Billings To ATC [Member]
Related Party Transactions [Line Items]
Amounts billed between related parties	$ 6	$ 4	$ 14	$ 13