Document And Entity Information
Document And Entity Information | 3 Months Ended |
Mar. 31, 2024 shares | |
Entity Information [Line Items] | |
Document Type | 10-Q |
Document Quarterly Report | true |
Document Period End Date | Mar. 31, 2024 |
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 | 256,379,032 |
Current Fiscal Year End Date | --12-31 |
Document Fiscal Year Focus | 2024 |
Document Fiscal Period Focus | Q1 |
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 | |
Mar. 31, 2024 | Mar. 31, 2023 | |
Revenues: | ||
Electric utility | $ 791 | $ 768 |
Gas utility | 205 | 276 |
Other utility | 13 | 11 |
Non-utility | 22 | 22 |
Total revenues | 1,031 | 1,077 |
Operating expenses: | ||
Electric production fuel and purchased power | 163 | 157 |
Electric transmission service | 152 | 146 |
Cost of gas sold | 114 | 181 |
Other operation and maintenance | 160 | 174 |
Depreciation and amortization | 189 | 166 |
Taxes other than income taxes | 31 | 31 |
Total operating expenses | 809 | 855 |
Operating income | 222 | 222 |
Other (income) and deductions: | ||
Interest expense | 107 | 94 |
Equity income from unconsolidated investments, net | (15) | (17) |
Allowance for funds used during construction | (19) | (19) |
Other | 1 | 3 |
Total other (income) and deductions | 74 | 61 |
Income before income taxes | 148 | 161 |
Income tax expense (benefit) | (10) | (2) |
Net income | 158 | 163 |
Net income attributable to common shareowners | $ 158 | $ 163 |
Weighted average number of common shares outstanding: | ||
Basic (in shares) | 256,200 | 251,200 |
Diluted (in shares) | 256,500 | 251,400 |
Earnings per weighted average common share attributable to Alliant Energy common shareowners: | ||
Basic (in dollars per share) | $ 0.62 | $ 0.65 |
Diluted (in dollars per share) | $ 0.62 | $ 0.65 |
IPL [Member] | ||
Revenues: | ||
Electric utility | $ 392 | $ 388 |
Gas utility | 108 | 150 |
Other utility | 13 | 11 |
Total revenues | 513 | 549 |
Operating expenses: | ||
Electric production fuel and purchased power | 67 | 47 |
Electric transmission service | 103 | 104 |
Cost of gas sold | 60 | 95 |
Other operation and maintenance | 86 | 95 |
Depreciation and amortization | 96 | 96 |
Taxes other than income taxes | 16 | 16 |
Total operating expenses | 428 | 453 |
Operating income | 85 | 96 |
Other (income) and deductions: | ||
Interest expense | 42 | 37 |
Allowance for funds used during construction | (10) | (3) |
Other | 0 | 1 |
Total other (income) and deductions | 32 | 35 |
Income before income taxes | 53 | 61 |
Income tax expense (benefit) | (10) | (11) |
Net income | 63 | 72 |
WPL [Member] | ||
Revenues: | ||
Electric utility | 399 | 380 |
Gas utility | 97 | 126 |
Total revenues | 496 | 506 |
Operating expenses: | ||
Electric production fuel and purchased power | 96 | 109 |
Electric transmission service | 49 | 42 |
Cost of gas sold | 53 | 86 |
Other operation and maintenance | 63 | 66 |
Depreciation and amortization | 90 | 68 |
Taxes other than income taxes | 14 | 14 |
Total operating expenses | 365 | 385 |
Operating income | 131 | 121 |
Other (income) and deductions: | ||
Interest expense | 41 | 36 |
Allowance for funds used during construction | (9) | (16) |
Other | 1 | 1 |
Total other (income) and deductions | 33 | 21 |
Income before income taxes | 98 | 100 |
Income tax expense (benefit) | 6 | 12 |
Net income | $ 92 | $ 88 |
Condensed Consolidated Balance
Condensed Consolidated Balance Sheets - USD ($) $ in Millions | Mar. 31, 2024 | Dec. 31, 2023 |
Current assets: | ||
Cash and cash equivalents | $ 32 | $ 62 |
Accounts receivable, less allowance for expected credit losses | 426 | 475 |
Production fuel, at weighted average cost | 60 | 62 |
Gas stored underground, at weighted average cost | 52 | 79 |
Materials and supplies, at weighted average cost | 208 | 202 |
Regulatory assets | 218 | 232 |
Other | 112 | 160 |
Total current assets | 1,108 | 1,272 |
Property, plant and equipment, net | 17,354 | 17,157 |
Investments: | ||
ATC Holdings | 392 | 386 |
Other | 219 | 216 |
Total investments | 611 | 602 |
Other assets: | ||
Regulatory assets | 2,002 | 2,029 |
Deferred charges and other | 173 | 177 |
Total other assets | 2,175 | 2,206 |
Total assets | 21,248 | 21,237 |
Current liabilities: | ||
Current maturities of long-term debt | 809 | 809 |
Commercial paper | 334 | 475 |
Accounts payable | 438 | 611 |
Regulatory liabilities | 100 | 107 |
Other | 303 | 302 |
Total current liabilities | 1,984 | 2,304 |
Long-term debt, net (excluding current portion) | 8,524 | 8,225 |
Other liabilities: | ||
Deferred tax liabilities | 2,038 | 2,042 |
Regulatory liabilities | 1,036 | 1,023 |
Pension and other benefit obligations | 245 | 249 |
Other | 604 | 617 |
Total other liabilities | 3,923 | 3,931 |
Commitments and contingencies (Note 13) | ||
Common equity: | ||
Common stock | 3 | 3 |
Additional paid-in capital | 3,033 | 3,030 |
Retained earnings | 3,791 | 3,756 |
Accumulated other comprehensive income | 2 | 1 |
Shares in deferred compensation trust - 341,937 and 379,006 shares at a weighted average cost of $34.96 and $34.48 per share | (12) | (13) |
Total common equity | 6,817 | 6,777 |
Total liabilities and equity | 21,248 | 21,237 |
IPL [Member] | ||
Current assets: | ||
Cash and cash equivalents | 12 | 53 |
Accounts receivable, less allowance for expected credit losses | 204 | 242 |
Production fuel, at weighted average cost | 29 | 27 |
Gas stored underground, at weighted average cost | 17 | 35 |
Materials and supplies, at weighted average cost | 126 | 122 |
Regulatory assets | 85 | 93 |
Other | 42 | 51 |
Total current assets | 515 | 623 |
Property, plant and equipment, net | 8,450 | 8,298 |
Other assets: | ||
Regulatory assets | 1,482 | 1,484 |
Deferred charges and other | 85 | 84 |
Total other assets | 1,567 | 1,568 |
Total assets | 10,532 | 10,489 |
Current liabilities: | ||
Current maturities of long-term debt | 500 | 500 |
Accounts payable | 213 | 262 |
Accrued taxes | 61 | 50 |
Accrued interest | 49 | 40 |
Regulatory liabilities | 79 | 72 |
Other | 97 | 101 |
Total current liabilities | 999 | 1,025 |
Long-term debt, net (excluding current portion) | 3,445 | 3,445 |
Other liabilities: | ||
Deferred tax liabilities | 1,098 | 1,091 |
Regulatory liabilities | 569 | 572 |
Pension and other benefit obligations | 49 | 51 |
Other | 335 | 331 |
Total other liabilities | 2,051 | 2,045 |
Commitments and contingencies (Note 13) | ||
Common equity: | ||
Common stock | 33 | 33 |
Additional paid-in capital | 2,937 | 2,887 |
Retained earnings | 1,067 | 1,054 |
Total common equity | 4,037 | 3,974 |
Total liabilities and equity | 10,532 | 10,489 |
WPL [Member] | ||
Current assets: | ||
Cash and cash equivalents | 11 | 7 |
Accounts receivable, less allowance for expected credit losses | 209 | 219 |
Production fuel, at weighted average cost | 31 | 35 |
Gas stored underground, at weighted average cost | 35 | 44 |
Materials and supplies, at weighted average cost | 78 | 77 |
Regulatory assets | 133 | 139 |
Prepaid gross receipts tax | 38 | 49 |
Other | 19 | 43 |
Total current assets | 554 | 613 |
Property, plant and equipment, net | 8,450 | 8,415 |
Other assets: | ||
Regulatory assets | 520 | 545 |
Deferred charges and other | 57 | 61 |
Total other assets | 577 | 606 |
Total assets | 9,581 | 9,634 |
Current liabilities: | ||
Commercial paper | 0 | 318 |
Accounts payable | 174 | 293 |
Accrued interest | 42 | 40 |
Regulatory liabilities | 21 | 35 |
Other | 105 | 89 |
Total current liabilities | 342 | 775 |
Long-term debt, net (excluding current portion) | 3,367 | 3,070 |
Other liabilities: | ||
Deferred tax liabilities | 811 | 827 |
Regulatory liabilities | 467 | 451 |
Pension and other benefit obligations | 119 | 121 |
Other | 480 | 493 |
Total other liabilities | 1,877 | 1,892 |
Commitments and contingencies (Note 13) | ||
Common equity: | ||
Common stock | 66 | 66 |
Additional paid-in capital | 2,533 | 2,478 |
Retained earnings | 1,396 | 1,353 |
Total common equity | 3,995 | 3,897 |
Total liabilities and equity | $ 9,581 | $ 9,634 |
Condensed Consolidated Balanc_2
Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares | Mar. 31, 2024 | Dec. 31, 2023 |
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) | 256,379,032 | 256,096,848 |
Shares in deferred compensation trust (in shares) | 341,937 | 379,006 |
Shares in deferred compensation trust, weighted average cost per share (in dollars per share) | $ 34.96 | $ 34.48 |
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 | 3 Months Ended | |
Mar. 31, 2024 | Mar. 31, 2023 | |
Cash flows from operating activities: | ||
Net income | $ 158 | $ 163 |
Adjustments to reconcile net income to net cash flows from operating activities: | ||
Depreciation and amortization | 189 | 166 |
Other | (18) | (6) |
Other changes in assets and liabilities: | ||
Accounts receivable | (116) | (86) |
Gas stored underground | 27 | 68 |
Derivative assets | 30 | 115 |
Regulatory assets | 35 | (32) |
Accounts payable | 12 | (97) |
Regulatory liabilities | (14) | (95) |
Other | 4 | (8) |
Net cash flows from operating activities | 307 | 188 |
Cash flows from (used for) investing activities: | ||
Utility business construction and acquisition expenditures | (478) | (417) |
Other construction and acquisition expenditures | (32) | (34) |
Cash receipts on sold receivables | 155 | 173 |
Proceeds from sale of partial ownership interest in West Riverside | 0 | 25 |
Other | 2 | (10) |
Net cash flows from (used for) investing activities | (353) | (263) |
Cash flows from (used for) financing activities: | ||
Common stock dividends | (123) | (113) |
Proceeds from issuance of long-term debt | 597 | 862 |
Payments to retire long-term debt | (300) | 0 |
Net change in commercial paper and other short-term borrowings | (141) | (532) |
Other | (15) | (5) |
Net cash flows from (used for) financing activities | 18 | 212 |
Net increase (decrease) in cash, cash equivalents and restricted cash | (28) | 137 |
Cash, cash equivalents and restricted cash at beginning of period | 63 | 24 |
Cash, cash equivalents and restricted cash at end of period | 35 | 161 |
Supplemental cash flows information: | ||
Interest | (97) | (93) |
Income taxes, net | (2) | 0 |
Significant non-cash investing and financing activities: | ||
Accrued capital expenditures | 204 | 254 |
Beneficial interest obtained in exchange for securitized accounts receivable | 184 | 153 |
IPL [Member] | ||
Cash flows from operating activities: | ||
Net income | 63 | 72 |
Adjustments to reconcile net income to net cash flows from operating activities: | ||
Depreciation and amortization | 96 | 96 |
Other | (11) | 1 |
Other changes in assets and liabilities: | ||
Accounts receivable | (119) | (106) |
Gas stored underground | 18 | 34 |
Derivative assets | 20 | 69 |
Accounts payable | (7) | (56) |
Regulatory liabilities | 4 | (59) |
Other | 12 | (27) |
Net cash flows from operating activities | 76 | 24 |
Cash flows from (used for) investing activities: | ||
Utility business construction and acquisition expenditures | (253) | (101) |
Cash receipts on sold receivables | 155 | 173 |
Other | (9) | (2) |
Net cash flows from (used for) investing activities | (107) | 70 |
Cash flows from (used for) financing activities: | ||
Common stock dividends | (50) | (70) |
Capital contributions from parent | 50 | 0 |
Other | (10) | (4) |
Net cash flows from (used for) financing activities | (10) | (74) |
Net increase (decrease) in cash, cash equivalents and restricted cash | (41) | 20 |
Cash, cash equivalents and restricted cash at beginning of period | 53 | 15 |
Cash, cash equivalents and restricted cash at end of period | 12 | 35 |
Supplemental cash flows information: | ||
Interest | (32) | (37) |
Income taxes, net | (2) | 0 |
Significant non-cash investing and financing activities: | ||
Accrued capital expenditures | 110 | 98 |
Beneficial interest obtained in exchange for securitized accounts receivable | 184 | 153 |
WPL [Member] | ||
Cash flows from operating activities: | ||
Net income | 92 | 88 |
Adjustments to reconcile net income to net cash flows from operating activities: | ||
Depreciation and amortization | 90 | 68 |
Other | (11) | (12) |
Other changes in assets and liabilities: | ||
Gas stored underground | 9 | 35 |
Derivative assets | 12 | 46 |
Regulatory assets | 29 | (37) |
Accounts payable | 15 | (48) |
Derivative liabilities | (4) | 28 |
Regulatory liabilities | (18) | (35) |
Other | 27 | 52 |
Net cash flows from operating activities | 241 | 185 |
Cash flows from (used for) investing activities: | ||
Utility business construction and acquisition expenditures | (225) | (316) |
Proceeds from sale of partial ownership interest in West Riverside | 0 | 25 |
Other | 12 | (4) |
Net cash flows from (used for) investing activities | (213) | (295) |
Cash flows from (used for) financing activities: | ||
Common stock dividends | (49) | (46) |
Capital contributions from parent | 55 | 180 |
Proceeds from issuance of long-term debt | 297 | 297 |
Net change in commercial paper and other short-term borrowings | (318) | (230) |
Other | (9) | (10) |
Net cash flows from (used for) financing activities | (24) | 191 |
Net increase (decrease) in cash, cash equivalents and restricted cash | 4 | 81 |
Cash, cash equivalents and restricted cash at beginning of period | 7 | 5 |
Cash, cash equivalents and restricted cash at end of period | 11 | 86 |
Supplemental cash flows information: | ||
Interest | (40) | (40) |
Significant non-cash investing and financing activities: | ||
Accrued capital expenditures | $ 91 | $ 152 |
Summary Of Significant Accounti
Summary Of Significant Accounting Policies | 3 Months Ended |
Mar. 31, 2024 | |
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 2023 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 three months ended March 31, 2024 are not necessarily indicative of results that may be expected for the year ending December 31, 2024. 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. |
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 2023 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 three months ended March 31, 2024 are not necessarily indicative of results that may be expected for the year ending December 31, 2024. 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. |
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 2023 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 three months ended March 31, 2024 are not necessarily indicative of results that may be expected for the year ending December 31, 2024. 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. |
Regulatory Matters
Regulatory Matters | 3 Months Ended |
Mar. 31, 2024 | |
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 March 31, December 31, March 31, December 31, March 31, December 31, Tax-related $939 $934 $839 $831 $100 $103 Pension and OPEB costs 340 347 168 171 172 176 Assets retired early 267 273 253 259 14 14 Asset retirement obligations (AROs) 200 194 165 160 35 34 Commodity cost recovery 100 120 5 12 95 108 Derivatives 97 102 33 34 64 68 WPL’s Western Wisconsin gas distribution expansion investments 44 44 — — 44 44 IPL’s Duane Arnold Energy Center PPA amendment 36 42 36 42 — — Other 197 205 68 68 129 137 $2,220 $2,261 $1,567 $1,577 $653 $684 Derivatives - Refer to Note 1 0 for discussion of changes in Alliant Energy’s, IPL’s and WPL’s derivative liabilities/assets during the three months ended March 31, 2024, which resulted 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 March 31, December 31, March 31, December 31, March 31, December 31, Tax-related $563 $566 $297 $299 $266 $267 Cost of removal obligations 380 366 241 242 139 124 Derivatives 49 65 28 34 21 31 Commodity cost recovery 61 48 25 13 36 35 Other 83 85 57 56 26 29 $1,136 $1,130 $648 $644 $488 $486 |
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 March 31, December 31, March 31, December 31, March 31, December 31, Tax-related $939 $934 $839 $831 $100 $103 Pension and OPEB costs 340 347 168 171 172 176 Assets retired early 267 273 253 259 14 14 Asset retirement obligations (AROs) 200 194 165 160 35 34 Commodity cost recovery 100 120 5 12 95 108 Derivatives 97 102 33 34 64 68 WPL’s Western Wisconsin gas distribution expansion investments 44 44 — — 44 44 IPL’s Duane Arnold Energy Center PPA amendment 36 42 36 42 — — Other 197 205 68 68 129 137 $2,220 $2,261 $1,567 $1,577 $653 $684 Derivatives - Refer to Note 1 0 for discussion of changes in Alliant Energy’s, IPL’s and WPL’s derivative liabilities/assets during the three months ended March 31, 2024, which resulted 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 March 31, December 31, March 31, December 31, March 31, December 31, Tax-related $563 $566 $297 $299 $266 $267 Cost of removal obligations 380 366 241 242 139 124 Derivatives 49 65 28 34 21 31 Commodity cost recovery 61 48 25 13 36 35 Other 83 85 57 56 26 29 $1,136 $1,130 $648 $644 $488 $486 |
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 March 31, December 31, March 31, December 31, March 31, December 31, Tax-related $939 $934 $839 $831 $100 $103 Pension and OPEB costs 340 347 168 171 172 176 Assets retired early 267 273 253 259 14 14 Asset retirement obligations (AROs) 200 194 165 160 35 34 Commodity cost recovery 100 120 5 12 95 108 Derivatives 97 102 33 34 64 68 WPL’s Western Wisconsin gas distribution expansion investments 44 44 — — 44 44 IPL’s Duane Arnold Energy Center PPA amendment 36 42 36 42 — — Other 197 205 68 68 129 137 $2,220 $2,261 $1,567 $1,577 $653 $684 Derivatives - Refer to Note 1 0 for discussion of changes in Alliant Energy’s, IPL’s and WPL’s derivative liabilities/assets during the three months ended March 31, 2024, which resulted 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 March 31, December 31, March 31, December 31, March 31, December 31, Tax-related $563 $566 $297 $299 $266 $267 Cost of removal obligations 380 366 241 242 139 124 Derivatives 49 65 28 34 21 31 Commodity cost recovery 61 48 25 13 36 35 Other 83 85 57 56 26 29 $1,136 $1,130 $648 $644 $488 $486 |
Property, Plant and Equipment
Property, Plant and Equipment | 3 Months Ended |
Mar. 31, 2024 | |
Property, Plant and Equipment [Line Items] | |
Property, Plant and Equipment | PROPERTY, PLANT AND EQUIPMENT WPL currently expects construction costs associated with its approximately 1,100 MW of new solar generation will exceed the construction cost estimates previously approved by the PSCW by approximately $180 million. In February 2024, the PSCW issued an order approving deferral of the incremental solar generation construction costs. The PSCW’s order did not authorize a deferral for the return on such costs. In March 2024, WPL filed for judicial review of the PSCW’s retail electric rate review order (2024/2025 forward-looking Test Period) and solar generation construction cost deferral order related to the recovery and deferral of the return on the incremental solar generation construction costs in 2024 and 2025. Alliant Energy and WPL concluded that there was not a probable disallowance of anticipated higher rate base amounts as of March 31, 2024 given construction costs were reasonably and prudently incurred. |
WPL [Member] | |
Property, Plant and Equipment [Line Items] | |
Property, Plant and Equipment | PROPERTY, PLANT AND EQUIPMENT WPL currently expects construction costs associated with its approximately 1,100 MW of new solar generation will exceed the construction cost estimates previously approved by the PSCW by approximately $180 million. In February 2024, the PSCW issued an order approving deferral of the incremental solar generation construction costs. The PSCW’s order did not authorize a deferral for the return on such costs. In March 2024, WPL filed for judicial review of the PSCW’s retail electric rate review order (2024/2025 forward-looking Test Period) and solar generation construction cost deferral order related to the recovery and deferral of the return on the incremental solar generation construction costs in 2024 and 2025. Alliant Energy and WPL concluded that there was not a probable disallowance of anticipated higher rate base amounts as of March 31, 2024 given construction costs were reasonably and prudently incurred. |
Receivables
Receivables | 3 Months Ended |
Mar. 31, 2024 | |
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. In March 2024, IPL amended and extended through March 2026 the purchase commitment from the third party to which it sells its receivables. The transfers of receivables meet the criteria for sale accounting established by the transfer of financial assets accounting rules. As of March 31, 2024, IPL had $92 million of available capacity under its sales of accounts receivable program. IPL’s maximum and average outstanding aggregate cash proceeds (based on daily outstanding balances) related to the sales of accounts receivable program for the three months ended March 31 were as follows (in millions): 2024 2023 Maximum outstanding aggregate cash proceeds $79 $89 Average outstanding aggregate cash proceeds 24 58 The attributes of IPL’s receivables sold under the Receivables Agreement were as follows (in millions): March 31, 2024 December 31, 2023 Customer accounts receivable $125 $130 Unbilled utility revenues 89 98 Other receivables 1 1 Receivables sold to third party 215 229 Less: cash proceeds 18 1 Deferred proceeds 197 228 Less: allowance for expected credit losses 13 12 Fair value of deferred proceeds $184 $216 As of March 31, 2024, outstanding receivables past due under the Receivables Agreement were $22 million. Additional attributes of IPL’s receivables sold under the Receivables Agreement for the three months ended March 31 were as follows (in millions): 2024 2023 Collections $557 $591 Write-offs, net of recoveries 3 2 Effective April 2024, the limit on cash proceeds under the Receivables Agreement is $80 million. |
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. In March 2024, IPL amended and extended through March 2026 the purchase commitment from the third party to which it sells its receivables. The transfers of receivables meet the criteria for sale accounting established by the transfer of financial assets accounting rules. As of March 31, 2024, IPL had $92 million of available capacity under its sales of accounts receivable program. IPL’s maximum and average outstanding aggregate cash proceeds (based on daily outstanding balances) related to the sales of accounts receivable program for the three months ended March 31 were as follows (in millions): 2024 2023 Maximum outstanding aggregate cash proceeds $79 $89 Average outstanding aggregate cash proceeds 24 58 The attributes of IPL’s receivables sold under the Receivables Agreement were as follows (in millions): March 31, 2024 December 31, 2023 Customer accounts receivable $125 $130 Unbilled utility revenues 89 98 Other receivables 1 1 Receivables sold to third party 215 229 Less: cash proceeds 18 1 Deferred proceeds 197 228 Less: allowance for expected credit losses 13 12 Fair value of deferred proceeds $184 $216 As of March 31, 2024, outstanding receivables past due under the Receivables Agreement were $22 million. Additional attributes of IPL’s receivables sold under the Receivables Agreement for the three months ended March 31 were as follows (in millions): 2024 2023 Collections $557 $591 Write-offs, net of recoveries 3 2 Effective April 2024, the limit on cash proceeds under the Receivables Agreement is $80 million. |
Investments
Investments | 3 Months Ended |
Mar. 31, 2024 | |
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 months ended March 31 was as follows (in millions): 2024 2023 ATC Holdings ($12) ($13) Other (3) (4) ($15) ($17) |
Common Equity
Common Equity | 3 Months Ended |
Mar. 31, 2024 | |
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, 2024 256,096,848 Shareowner Direct Plan 127,917 Equity-based compensation plans 154,267 Shares outstanding, March 31, 2024 256,379,032 Changes in Shareowners’ Equity - A summary of changes in shareowners’ equity was as follows (in millions): Alliant Energy Accumulated Shares in Additional Other Deferred Total Common Paid-In Retained Comprehensive Compensation Common Stock Capital Earnings Income (Loss) Trust Equity Three Months Ended March 31, 2024 Beginning balance, December 31, 2023 $3 $3,030 $3,756 $1 ($13) $6,777 Net income attributable to Alliant Energy common shareowners 158 158 Common stock dividends ($0.48 per share) (123) (123) Shareowner Direct Plan issuances 6 6 Equity-based compensation plans and other (3) 1 (2) Other comprehensive income, net of tax 1 1 Ending balance, March 31, 2024 $3 $3,033 $3,791 $2 ($12) $6,817 Three Months Ended March 31, 2023 Beginning balance, December 31, 2022 $3 $2,777 $3,509 $— ($13) $6,276 Net income attributable to Alliant Energy common shareowners 163 163 Common stock dividends ($0.4525 per share) (113) (113) Shareowner Direct Plan issuances 6 6 Equity-based compensation plans and other (3) (3) Other comprehensive loss, net of tax (1) (1) Ending balance, March 31, 2023 $3 $2,780 $3,559 ($1) ($13) $6,328 IPL Additional Total Common Paid-In Retained Common Stock Capital Earnings Equity Three Months Ended March 31, 2024 Beginning balance, December 31, 2023 $33 $2,887 $1,054 $3,974 Net income 63 63 Common stock dividends (50) (50) Capital contributions from parent 50 50 Ending balance, March 31, 2024 $33 $2,937 $1,067 $4,037 Three Months Ended March 31, 2023 Beginning balance, December 31, 2022 $33 $2,807 $968 $3,808 Net income 72 72 Common stock dividends (70) (70) Ending balance, March 31, 2023 $33 $2,807 $970 $3,810 WPL Additional Total Common Paid-In Retained Common Stock Capital Earnings Equity Three Months Ended March 31, 2024 Beginning balance, December 31, 2023 $66 $2,478 $1,353 $3,897 Net income 92 92 Common stock dividends (49) (49) Capital contributions from parent 55 55 Ending balance, March 31, 2024 $66 $2,533 $1,396 $3,995 Three Months Ended March 31, 2023 Beginning balance, December 31, 2022 $66 $2,233 $1,192 $3,491 Net income 88 88 Common stock dividends (46) (46) Capital contributions from parent 180 180 Ending balance, March 31, 2023 $66 $2,413 $1,234 $3,713 |
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, 2024 256,096,848 Shareowner Direct Plan 127,917 Equity-based compensation plans 154,267 Shares outstanding, March 31, 2024 256,379,032 Changes in Shareowners’ Equity - A summary of changes in shareowners’ equity was as follows (in millions): Alliant Energy Accumulated Shares in Additional Other Deferred Total Common Paid-In Retained Comprehensive Compensation Common Stock Capital Earnings Income (Loss) Trust Equity Three Months Ended March 31, 2024 Beginning balance, December 31, 2023 $3 $3,030 $3,756 $1 ($13) $6,777 Net income attributable to Alliant Energy common shareowners 158 158 Common stock dividends ($0.48 per share) (123) (123) Shareowner Direct Plan issuances 6 6 Equity-based compensation plans and other (3) 1 (2) Other comprehensive income, net of tax 1 1 Ending balance, March 31, 2024 $3 $3,033 $3,791 $2 ($12) $6,817 Three Months Ended March 31, 2023 Beginning balance, December 31, 2022 $3 $2,777 $3,509 $— ($13) $6,276 Net income attributable to Alliant Energy common shareowners 163 163 Common stock dividends ($0.4525 per share) (113) (113) Shareowner Direct Plan issuances 6 6 Equity-based compensation plans and other (3) (3) Other comprehensive loss, net of tax (1) (1) Ending balance, March 31, 2023 $3 $2,780 $3,559 ($1) ($13) $6,328 IPL Additional Total Common Paid-In Retained Common Stock Capital Earnings Equity Three Months Ended March 31, 2024 Beginning balance, December 31, 2023 $33 $2,887 $1,054 $3,974 Net income 63 63 Common stock dividends (50) (50) Capital contributions from parent 50 50 Ending balance, March 31, 2024 $33 $2,937 $1,067 $4,037 Three Months Ended March 31, 2023 Beginning balance, December 31, 2022 $33 $2,807 $968 $3,808 Net income 72 72 Common stock dividends (70) (70) Ending balance, March 31, 2023 $33 $2,807 $970 $3,810 WPL Additional Total Common Paid-In Retained Common Stock Capital Earnings Equity Three Months Ended March 31, 2024 Beginning balance, December 31, 2023 $66 $2,478 $1,353 $3,897 Net income 92 92 Common stock dividends (49) (49) Capital contributions from parent 55 55 Ending balance, March 31, 2024 $66 $2,533 $1,396 $3,995 Three Months Ended March 31, 2023 Beginning balance, December 31, 2022 $66 $2,233 $1,192 $3,491 Net income 88 88 Common stock dividends (46) (46) Capital contributions from parent 180 180 Ending balance, March 31, 2023 $66 $2,413 $1,234 $3,713 |
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, 2024 256,096,848 Shareowner Direct Plan 127,917 Equity-based compensation plans 154,267 Shares outstanding, March 31, 2024 256,379,032 Changes in Shareowners’ Equity - A summary of changes in shareowners’ equity was as follows (in millions): Alliant Energy Accumulated Shares in Additional Other Deferred Total Common Paid-In Retained Comprehensive Compensation Common Stock Capital Earnings Income (Loss) Trust Equity Three Months Ended March 31, 2024 Beginning balance, December 31, 2023 $3 $3,030 $3,756 $1 ($13) $6,777 Net income attributable to Alliant Energy common shareowners 158 158 Common stock dividends ($0.48 per share) (123) (123) Shareowner Direct Plan issuances 6 6 Equity-based compensation plans and other (3) 1 (2) Other comprehensive income, net of tax 1 1 Ending balance, March 31, 2024 $3 $3,033 $3,791 $2 ($12) $6,817 Three Months Ended March 31, 2023 Beginning balance, December 31, 2022 $3 $2,777 $3,509 $— ($13) $6,276 Net income attributable to Alliant Energy common shareowners 163 163 Common stock dividends ($0.4525 per share) (113) (113) Shareowner Direct Plan issuances 6 6 Equity-based compensation plans and other (3) (3) Other comprehensive loss, net of tax (1) (1) Ending balance, March 31, 2023 $3 $2,780 $3,559 ($1) ($13) $6,328 IPL Additional Total Common Paid-In Retained Common Stock Capital Earnings Equity Three Months Ended March 31, 2024 Beginning balance, December 31, 2023 $33 $2,887 $1,054 $3,974 Net income 63 63 Common stock dividends (50) (50) Capital contributions from parent 50 50 Ending balance, March 31, 2024 $33 $2,937 $1,067 $4,037 Three Months Ended March 31, 2023 Beginning balance, December 31, 2022 $33 $2,807 $968 $3,808 Net income 72 72 Common stock dividends (70) (70) Ending balance, March 31, 2023 $33 $2,807 $970 $3,810 WPL Additional Total Common Paid-In Retained Common Stock Capital Earnings Equity Three Months Ended March 31, 2024 Beginning balance, December 31, 2023 $66 $2,478 $1,353 $3,897 Net income 92 92 Common stock dividends (49) (49) Capital contributions from parent 55 55 Ending balance, March 31, 2024 $66 $2,533 $1,396 $3,995 Three Months Ended March 31, 2023 Beginning balance, December 31, 2022 $66 $2,233 $1,192 $3,491 Net income 88 88 Common stock dividends (46) (46) Capital contributions from parent 180 180 Ending balance, March 31, 2023 $66 $2,413 $1,234 $3,713 |
Debt
Debt | 3 Months Ended |
Mar. 31, 2024 | |
Debt [Line Items] | |
Debt | DEBT NOTE 7(a) Short-term Debt - In March 2024, 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. Information regarding commercial paper classified as short-term debt was as follows (dollars in millions): March 31, 2024 Alliant Energy IPL WPL Amount outstanding $334 $— $— Weighted average interest rates 5.5% —% —% Available credit facility capacity $666 $200 $300 Alliant Energy IPL WPL Three Months Ended March 31 2024 2023 2024 2023 2024 2023 Maximum amount outstanding (based on daily outstanding balances) $632 $793 $14 $— $390 $349 Average amount outstanding (based on daily outstanding balances) $487 $574 $1 $— $255 $304 Weighted average interest rates 5.5% 4.8% 5.5% —% 5.5% 4.8% NOTE 7(b) Long-term Debt - In March 2024, AEF entered into a $300 million variable rate (6% as of March 31, 2024) term loan credit agreement (with Alliant Energy as guarantor), which expires in March 2025. This term loan credit agreement amends and restates the term loan credit agreement that expired in March 2024, and retired the $300 million variable rate term loan set forth therein. AEF’s restated term loan credit agreement includes an option to increase the amount outstanding with one or more additional term loans in an aggregate amount not to exceed $100 million. In March 2024, WPL issued $300 million of 5.375% debentures due 2034. WPL’s debentures were issued as green bonds, and an amount equal to or in excess of the net proceeds will be allocated or disbursed for the development and acquisition of WPL’s solar EGUs. Convertible Senior Notes - As of March 31, 2024, the conditions allowing holders of Alliant Energy’s convertible senior notes due 2026 (the Notes) to convert their Notes were not met, and as a result, the Notes were classified as “Long-term debt, net” on Alliant Energy’s balance sheet. As of March 31, 2024, the net carrying amount of the Notes was $569 million, with unamortized debt issuance costs of $6 million, and the estimated fair value (Level 2) of the Notes was $567 million. As of March 31, 2024, there were no shares of Alliant Energy’s common stock related to the potential conversion of the Notes included in diluted EPS based on Alliant Energy’s average stock prices and the relevant terms of the Notes. |
IPL [Member] | |
Debt [Line Items] | |
Debt | DEBT NOTE 7(a) Short-term Debt - In March 2024, 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. Information regarding commercial paper classified as short-term debt was as follows (dollars in millions): March 31, 2024 Alliant Energy IPL WPL Amount outstanding $334 $— $— Weighted average interest rates 5.5% —% —% Available credit facility capacity $666 $200 $300 Alliant Energy IPL WPL Three Months Ended March 31 2024 2023 2024 2023 2024 2023 Maximum amount outstanding (based on daily outstanding balances) $632 $793 $14 $— $390 $349 Average amount outstanding (based on daily outstanding balances) $487 $574 $1 $— $255 $304 Weighted average interest rates 5.5% 4.8% 5.5% —% 5.5% 4.8% |
WPL [Member] | |
Debt [Line Items] | |
Debt | DEBT NOTE 7(a) Short-term Debt - In March 2024, 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. Information regarding commercial paper classified as short-term debt was as follows (dollars in millions): March 31, 2024 Alliant Energy IPL WPL Amount outstanding $334 $— $— Weighted average interest rates 5.5% —% —% Available credit facility capacity $666 $200 $300 Alliant Energy IPL WPL Three Months Ended March 31 2024 2023 2024 2023 2024 2023 Maximum amount outstanding (based on daily outstanding balances) $632 $793 $14 $— $390 $349 Average amount outstanding (based on daily outstanding balances) $487 $574 $1 $— $255 $304 Weighted average interest rates 5.5% 4.8% 5.5% —% 5.5% 4.8% NOTE 7(b) Long-term Debt - In March 2024, AEF entered into a $300 million variable rate (6% as of March 31, 2024) term loan credit agreement (with Alliant Energy as guarantor), which expires in March 2025. This term loan credit agreement amends and restates the term loan credit agreement that expired in March 2024, and retired the $300 million variable rate term loan set forth therein. AEF’s restated term loan credit agreement includes an option to increase the amount outstanding with one or more additional term loans in an aggregate amount not to exceed $100 million. In March 2024, WPL issued $300 million of 5.375% debentures due 2034. WPL’s debentures were issued as green bonds, and an amount equal to or in excess of the net proceeds will be allocated or disbursed for the development and acquisition of WPL’s solar EGUs. |
Revenues
Revenues | 3 Months Ended |
Mar. 31, 2024 | |
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 March 31 2024 2023 2024 2023 2024 2023 Electric Utility: Retail - residential $297 $285 $150 $143 $147 $142 Retail - commercial 186 185 114 112 72 73 Retail - industrial 223 216 112 107 111 109 Wholesale 47 46 13 12 34 34 Bulk power and other 38 36 3 14 35 22 Total Electric Utility 791 768 392 388 399 380 Gas Utility: Retail - residential 126 167 68 93 58 74 Retail - commercial 61 88 30 44 31 44 Retail - industrial 5 7 3 4 2 3 Transportation/other 13 14 7 9 6 5 Total Gas Utility 205 276 108 150 97 126 Other Utility: Steam 12 10 12 10 — — Other utility 1 1 1 1 — — Total Other Utility 13 11 13 11 — — Non-Utility and Other: Travero and other 22 22 — — — — Total Non-Utility and Other 22 22 — — — — Total revenues $1,031 $1,077 $513 $549 $496 $506 |
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 March 31 2024 2023 2024 2023 2024 2023 Electric Utility: Retail - residential $297 $285 $150 $143 $147 $142 Retail - commercial 186 185 114 112 72 73 Retail - industrial 223 216 112 107 111 109 Wholesale 47 46 13 12 34 34 Bulk power and other 38 36 3 14 35 22 Total Electric Utility 791 768 392 388 399 380 Gas Utility: Retail - residential 126 167 68 93 58 74 Retail - commercial 61 88 30 44 31 44 Retail - industrial 5 7 3 4 2 3 Transportation/other 13 14 7 9 6 5 Total Gas Utility 205 276 108 150 97 126 Other Utility: Steam 12 10 12 10 — — Other utility 1 1 1 1 — — Total Other Utility 13 11 13 11 — — Non-Utility and Other: Travero and other 22 22 — — — — Total Non-Utility and Other 22 22 — — — — Total revenues $1,031 $1,077 $513 $549 $496 $506 |
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 March 31 2024 2023 2024 2023 2024 2023 Electric Utility: Retail - residential $297 $285 $150 $143 $147 $142 Retail - commercial 186 185 114 112 72 73 Retail - industrial 223 216 112 107 111 109 Wholesale 47 46 13 12 34 34 Bulk power and other 38 36 3 14 35 22 Total Electric Utility 791 768 392 388 399 380 Gas Utility: Retail - residential 126 167 68 93 58 74 Retail - commercial 61 88 30 44 31 44 Retail - industrial 5 7 3 4 2 3 Transportation/other 13 14 7 9 6 5 Total Gas Utility 205 276 108 150 97 126 Other Utility: Steam 12 10 12 10 — — Other utility 1 1 1 1 — — Total Other Utility 13 11 13 11 — — Non-Utility and Other: Travero and other 22 22 — — — — Total Non-Utility and Other 22 22 — — — — Total revenues $1,031 $1,077 $513 $549 $496 $506 |
Income Taxes
Income Taxes | 3 Months Ended |
Mar. 31, 2024 | |
Income Taxes [Line Items] | |
Income Taxes | INCOME TAXES Income Tax Rates - Overall effective income tax rates for the three months ended March 31, 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. Alliant Energy IPL WPL 2024 2023 2024 2023 2024 2023 Overall income tax rate (7%) (1%) (19%) (18%) 6% 12% Deferred Tax Assets and Liabilities - Carryforwards - At March 31, 2024, the carryforwards and expiration dates were estimated as follows (in millions): Range of Expiration Dates Alliant Energy IPL WPL State net operating losses 2025-2044 $403 $6 $1 Federal tax credits 2032-2044 685 462 214 |
IPL [Member] | |
Income Taxes [Line Items] | |
Income Taxes | INCOME TAXES Income Tax Rates - Overall effective income tax rates for the three months ended March 31, 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. Alliant Energy IPL WPL 2024 2023 2024 2023 2024 2023 Overall income tax rate (7%) (1%) (19%) (18%) 6% 12% Deferred Tax Assets and Liabilities - Carryforwards - At March 31, 2024, the carryforwards and expiration dates were estimated as follows (in millions): Range of Expiration Dates Alliant Energy IPL WPL State net operating losses 2025-2044 $403 $6 $1 Federal tax credits 2032-2044 685 462 214 |
WPL [Member] | |
Income Taxes [Line Items] | |
Income Taxes | INCOME TAXES Income Tax Rates - Overall effective income tax rates for the three months ended March 31, 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. Alliant Energy IPL WPL 2024 2023 2024 2023 2024 2023 Overall income tax rate (7%) (1%) (19%) (18%) 6% 12% Deferred Tax Assets and Liabilities - Carryforwards - At March 31, 2024, the carryforwards and expiration dates were estimated as follows (in millions): Range of Expiration Dates Alliant Energy IPL WPL State net operating losses 2025-2044 $403 $6 $1 Federal tax credits 2032-2044 685 462 214 |
Benefit Plans
Benefit Plans | 3 Months Ended |
Mar. 31, 2024 | |
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 months ended March 31 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 Alliant Energy 2024 2023 2024 2023 Service cost $1 $1 $— $1 Interest cost 11 11 2 2 Expected return on plan assets (13) (13) (1) (1) Amortization of actuarial loss 6 7 — — $5 $6 $1 $2 Defined Benefit Pension Plans OPEB Plans IPL 2024 2023 2024 2023 Service cost $1 $1 $— $— Interest cost 5 5 1 1 Expected return on plan assets (7) (7) (1) (1) Amortization of actuarial loss 2 3 — — $1 $2 $— $— Defined Benefit Pension Plans OPEB Plans WPL 2024 2023 2024 2023 Interest cost $5 $5 $1 $1 Expected return on plan assets (6) (5) — — Amortization of actuarial loss 3 3 — — $2 $3 $1 $1 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 months ended March 31 was as follows (in millions): Alliant Energy IPL WPL 2024 2023 2024 2023 2024 2023 Compensation expense $4 $3 $2 $2 $2 $1 Income tax benefits 1 1 1 — — — As of March 31, 2024, Alliant Energy’s, IPL’s and WPL’s total unrecognized compensation cost related to share-based compensation awards was $22 million, $11 million and $10 million, respectively, which is expected to be recognized over a weighted average period of between 1 year and 2 years. For the three months ended March 31, 2024, performance shares and restricted stock units were granted to key employees under the equity-based compensation 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 (total shareowner return metric) 123,098 $46.04 Performance shares (net income and diversity metrics) (formerly granted as performance restricted stock units) 140,683 48.40 Restricted stock units 120,557 48.40 As of March 31, 2024, 242,680 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 months ended March 31 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 Alliant Energy 2024 2023 2024 2023 Service cost $1 $1 $— $1 Interest cost 11 11 2 2 Expected return on plan assets (13) (13) (1) (1) Amortization of actuarial loss 6 7 — — $5 $6 $1 $2 Defined Benefit Pension Plans OPEB Plans IPL 2024 2023 2024 2023 Service cost $1 $1 $— $— Interest cost 5 5 1 1 Expected return on plan assets (7) (7) (1) (1) Amortization of actuarial loss 2 3 — — $1 $2 $— $— Defined Benefit Pension Plans OPEB Plans WPL 2024 2023 2024 2023 Interest cost $5 $5 $1 $1 Expected return on plan assets (6) (5) — — Amortization of actuarial loss 3 3 — — $2 $3 $1 $1 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 months ended March 31 was as follows (in millions): Alliant Energy IPL WPL 2024 2023 2024 2023 2024 2023 Compensation expense $4 $3 $2 $2 $2 $1 Income tax benefits 1 1 1 — — — As of March 31, 2024, Alliant Energy’s, IPL’s and WPL’s total unrecognized compensation cost related to share-based compensation awards was $22 million, $11 million and $10 million, respectively, which is expected to be recognized over a weighted average period of between 1 year and 2 years. For the three months ended March 31, 2024, performance shares and restricted stock units were granted to key employees under the equity-based compensation 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 (total shareowner return metric) 123,098 $46.04 Performance shares (net income and diversity metrics) (formerly granted as performance restricted stock units) 140,683 48.40 Restricted stock units 120,557 48.40 As of March 31, 2024, 242,680 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 months ended March 31 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 Alliant Energy 2024 2023 2024 2023 Service cost $1 $1 $— $1 Interest cost 11 11 2 2 Expected return on plan assets (13) (13) (1) (1) Amortization of actuarial loss 6 7 — — $5 $6 $1 $2 Defined Benefit Pension Plans OPEB Plans IPL 2024 2023 2024 2023 Service cost $1 $1 $— $— Interest cost 5 5 1 1 Expected return on plan assets (7) (7) (1) (1) Amortization of actuarial loss 2 3 — — $1 $2 $— $— Defined Benefit Pension Plans OPEB Plans WPL 2024 2023 2024 2023 Interest cost $5 $5 $1 $1 Expected return on plan assets (6) (5) — — Amortization of actuarial loss 3 3 — — $2 $3 $1 $1 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 months ended March 31 was as follows (in millions): Alliant Energy IPL WPL 2024 2023 2024 2023 2024 2023 Compensation expense $4 $3 $2 $2 $2 $1 Income tax benefits 1 1 1 — — — As of March 31, 2024, Alliant Energy’s, IPL’s and WPL’s total unrecognized compensation cost related to share-based compensation awards was $22 million, $11 million and $10 million, respectively, which is expected to be recognized over a weighted average period of between 1 year and 2 years. For the three months ended March 31, 2024, performance shares and restricted stock units were granted to key employees under the equity-based compensation 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 (total shareowner return metric) 123,098 $46.04 Performance shares (net income and diversity metrics) (formerly granted as performance restricted stock units) 140,683 48.40 Restricted stock units 120,557 48.40 As of March 31, 2024, 242,680 shares were included in the calculation of diluted EPS related to the nonvested equity awards. |
Derivative Instruments
Derivative Instruments | 3 Months Ended |
Mar. 31, 2024 | |
Derivative Instruments [Line Items] | |
Derivative Instruments | DERIVATIVE INSTRUMENTS Commodity Derivatives - Notional Amounts - As of March 31, 2024, 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 MWhs Years MWhs Years Dths Years Alliant Energy 1,412 2024-2026 4,162 2024 173,746 2024-2032 IPL 673 2024-2026 1,444 2024 78,790 2024-2030 WPL 739 2024-2026 2,718 2024 94,956 2024-2032 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 March 31, December 31, March 31, December 31, March 31, December 31, Current derivative assets $16 $44 $12 $30 $4 $14 Non-current derivative assets 40 44 22 24 18 20 Current derivative liabilities 49 51 23 22 26 29 Non-current derivative liabilities 45 47 7 8 38 39 During the three months ended March 31, 2024, Alliant Energy’s, IPL’s and WPL’s derivative assets decreased primarily due to settlements of FTRs, natural gas and electricity contracts, and lower natural gas prices. 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 March 31, 2024 and December 31, 2023, 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 March 31, 2024 Derivative assets $56 $26 $34 $17 $22 $9 Derivative liabilities 94 64 30 13 64 51 December 31, 2023 Derivative assets 88 47 54 32 34 15 Derivative liabilities 98 57 30 8 68 49 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. Interest Rate Derivative - The interest rate derivative associated with AEF’s interest rate swap maturing in January 2026 was valued based on quoted prices that utilize current market interest rate forecasts. As of March 31, 2024 , $3 million of non-current interest rate derivative assets was recorded in “Deferred charges and other” on Alliant Energy’s balance sheet. This interest rate derivative was designated as a cash flow hedge, with changes in fair value recorded as other comprehensive income/loss. As of March 31, 2024, accumulated other comprehensive income included $2 million of income related to the interest rate swap. For the three months ended March 31, 2024 and 2023 , $1 million and $1 million , respectively, of reductions to interest expense were recorded in Alliant Energy’s income statement related to the interest rate swap. |
IPL [Member] | |
Derivative Instruments [Line Items] | |
Derivative Instruments | DERIVATIVE INSTRUMENTS Commodity Derivatives - Notional Amounts - As of March 31, 2024, 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 MWhs Years MWhs Years Dths Years Alliant Energy 1,412 2024-2026 4,162 2024 173,746 2024-2032 IPL 673 2024-2026 1,444 2024 78,790 2024-2030 WPL 739 2024-2026 2,718 2024 94,956 2024-2032 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 March 31, December 31, March 31, December 31, March 31, December 31, Current derivative assets $16 $44 $12 $30 $4 $14 Non-current derivative assets 40 44 22 24 18 20 Current derivative liabilities 49 51 23 22 26 29 Non-current derivative liabilities 45 47 7 8 38 39 During the three months ended March 31, 2024, Alliant Energy’s, IPL’s and WPL’s derivative assets decreased primarily due to settlements of FTRs, natural gas and electricity contracts, and lower natural gas prices. 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 March 31, 2024 and December 31, 2023, 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 March 31, 2024 Derivative assets $56 $26 $34 $17 $22 $9 Derivative liabilities 94 64 30 13 64 51 December 31, 2023 Derivative assets 88 47 54 32 34 15 Derivative liabilities 98 57 30 8 68 49 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 March 31, 2024, 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 MWhs Years MWhs Years Dths Years Alliant Energy 1,412 2024-2026 4,162 2024 173,746 2024-2032 IPL 673 2024-2026 1,444 2024 78,790 2024-2030 WPL 739 2024-2026 2,718 2024 94,956 2024-2032 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 March 31, December 31, March 31, December 31, March 31, December 31, Current derivative assets $16 $44 $12 $30 $4 $14 Non-current derivative assets 40 44 22 24 18 20 Current derivative liabilities 49 51 23 22 26 29 Non-current derivative liabilities 45 47 7 8 38 39 During the three months ended March 31, 2024, Alliant Energy’s, IPL’s and WPL’s derivative assets decreased primarily due to settlements of FTRs, natural gas and electricity contracts, and lower natural gas prices. 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 March 31, 2024 and December 31, 2023, 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 March 31, 2024 Derivative assets $56 $26 $34 $17 $22 $9 Derivative liabilities 94 64 30 13 64 51 December 31, 2023 Derivative assets 88 47 54 32 34 15 Derivative liabilities 98 57 30 8 68 49 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 | 3 Months Ended |
Mar. 31, 2024 | |
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 March 31, 2024 December 31, 2023 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 $10 $10 $— $— $10 $45 $45 $— $— $45 Commodity derivatives 56 — 46 10 56 88 — 59 29 88 Interest rate derivatives 3 — 3 — 3 1 — 1 — 1 Deferred proceeds 184 — — 184 184 216 — — 216 216 Liabilities: Commodity derivatives 94 — 91 3 94 98 — 93 5 98 Long-term debt (incl. current maturities) 9,333 — 9,051 — 9,051 9,034 — 8,677 — 8,677 IPL March 31, 2024 December 31, 2023 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 $6 $6 $— $— $6 $45 $45 $— $— $45 Commodity derivatives 34 — 26 8 34 54 — 30 24 54 Deferred proceeds 184 — — 184 184 216 — — 216 216 Liabilities: Commodity derivatives 30 — 27 3 30 30 — 25 5 30 Long-term debt (incl. current maturities) 3,945 — 3,607 — 3,607 3,945 — 3,664 — 3,664 WPL March 31, 2024 December 31, 2023 Fair Value Fair Value Carrying Level Level Level Carrying Level Level Level Amount 1 2 3 Total Amount 1 2 3 Total Assets: Commodity derivatives $22 $— $20 $2 $22 $34 $— $29 $5 $34 Liabilities: Commodity derivatives 64 — 64 — 64 68 — 68 — 68 Long-term debt 3,367 — 3,176 — 3,176 3,070 — 2,933 — 2,933 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 March 31 2024 2023 2024 2023 Beginning balance, January 1 $24 $19 $216 $185 Total net losses included in changes in net assets (realized/unrealized) (3) (4) — — Settlements (a) (14) (20) (32) (32) Ending balance, March 31 $7 ($5) $184 $153 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 March 31 ($3) ($4) $— $— IPL Commodity Contract Derivative Assets and (Liabilities), net Deferred Proceeds Three Months Ended March 31 2024 2023 2024 2023 Beginning balance, January 1 $19 $16 $216 $185 Total net gains (losses) included in changes in net assets (realized/unrealized) (4) 1 — — Settlements (a) (10) (17) (32) (32) Ending balance, March 31 $5 $— $184 $153 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 March 31 ($4) $1 $— $— WPL Commodity Contract Derivative Assets and (Liabilities), net Three Months Ended March 31 2024 2023 Beginning balance, January 1 $5 $3 Total net gains (losses) included in changes in net assets (realized/unrealized) 1 (5) Settlements (4) (3) Ending balance, March 31 $2 ($5) 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 March 31 $1 ($5) (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 March 31, 2024 ($1) $8 ($1) $6 $— $2 December 31, 2023 3 21 3 16 — 5 |
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 March 31, 2024 December 31, 2023 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 $10 $10 $— $— $10 $45 $45 $— $— $45 Commodity derivatives 56 — 46 10 56 88 — 59 29 88 Interest rate derivatives 3 — 3 — 3 1 — 1 — 1 Deferred proceeds 184 — — 184 184 216 — — 216 216 Liabilities: Commodity derivatives 94 — 91 3 94 98 — 93 5 98 Long-term debt (incl. current maturities) 9,333 — 9,051 — 9,051 9,034 — 8,677 — 8,677 IPL March 31, 2024 December 31, 2023 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 $6 $6 $— $— $6 $45 $45 $— $— $45 Commodity derivatives 34 — 26 8 34 54 — 30 24 54 Deferred proceeds 184 — — 184 184 216 — — 216 216 Liabilities: Commodity derivatives 30 — 27 3 30 30 — 25 5 30 Long-term debt (incl. current maturities) 3,945 — 3,607 — 3,607 3,945 — 3,664 — 3,664 WPL March 31, 2024 December 31, 2023 Fair Value Fair Value Carrying Level Level Level Carrying Level Level Level Amount 1 2 3 Total Amount 1 2 3 Total Assets: Commodity derivatives $22 $— $20 $2 $22 $34 $— $29 $5 $34 Liabilities: Commodity derivatives 64 — 64 — 64 68 — 68 — 68 Long-term debt 3,367 — 3,176 — 3,176 3,070 — 2,933 — 2,933 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 March 31 2024 2023 2024 2023 Beginning balance, January 1 $24 $19 $216 $185 Total net losses included in changes in net assets (realized/unrealized) (3) (4) — — Settlements (a) (14) (20) (32) (32) Ending balance, March 31 $7 ($5) $184 $153 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 March 31 ($3) ($4) $— $— IPL Commodity Contract Derivative Assets and (Liabilities), net Deferred Proceeds Three Months Ended March 31 2024 2023 2024 2023 Beginning balance, January 1 $19 $16 $216 $185 Total net gains (losses) included in changes in net assets (realized/unrealized) (4) 1 — — Settlements (a) (10) (17) (32) (32) Ending balance, March 31 $5 $— $184 $153 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 March 31 ($4) $1 $— $— WPL Commodity Contract Derivative Assets and (Liabilities), net Three Months Ended March 31 2024 2023 Beginning balance, January 1 $5 $3 Total net gains (losses) included in changes in net assets (realized/unrealized) 1 (5) Settlements (4) (3) Ending balance, March 31 $2 ($5) 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 March 31 $1 ($5) (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 March 31, 2024 ($1) $8 ($1) $6 $— $2 December 31, 2023 3 21 3 16 — 5 |
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 March 31, 2024 December 31, 2023 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 $10 $10 $— $— $10 $45 $45 $— $— $45 Commodity derivatives 56 — 46 10 56 88 — 59 29 88 Interest rate derivatives 3 — 3 — 3 1 — 1 — 1 Deferred proceeds 184 — — 184 184 216 — — 216 216 Liabilities: Commodity derivatives 94 — 91 3 94 98 — 93 5 98 Long-term debt (incl. current maturities) 9,333 — 9,051 — 9,051 9,034 — 8,677 — 8,677 IPL March 31, 2024 December 31, 2023 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 $6 $6 $— $— $6 $45 $45 $— $— $45 Commodity derivatives 34 — 26 8 34 54 — 30 24 54 Deferred proceeds 184 — — 184 184 216 — — 216 216 Liabilities: Commodity derivatives 30 — 27 3 30 30 — 25 5 30 Long-term debt (incl. current maturities) 3,945 — 3,607 — 3,607 3,945 — 3,664 — 3,664 WPL March 31, 2024 December 31, 2023 Fair Value Fair Value Carrying Level Level Level Carrying Level Level Level Amount 1 2 3 Total Amount 1 2 3 Total Assets: Commodity derivatives $22 $— $20 $2 $22 $34 $— $29 $5 $34 Liabilities: Commodity derivatives 64 — 64 — 64 68 — 68 — 68 Long-term debt 3,367 — 3,176 — 3,176 3,070 — 2,933 — 2,933 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 March 31 2024 2023 2024 2023 Beginning balance, January 1 $24 $19 $216 $185 Total net losses included in changes in net assets (realized/unrealized) (3) (4) — — Settlements (a) (14) (20) (32) (32) Ending balance, March 31 $7 ($5) $184 $153 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 March 31 ($3) ($4) $— $— IPL Commodity Contract Derivative Assets and (Liabilities), net Deferred Proceeds Three Months Ended March 31 2024 2023 2024 2023 Beginning balance, January 1 $19 $16 $216 $185 Total net gains (losses) included in changes in net assets (realized/unrealized) (4) 1 — — Settlements (a) (10) (17) (32) (32) Ending balance, March 31 $5 $— $184 $153 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 March 31 ($4) $1 $— $— WPL Commodity Contract Derivative Assets and (Liabilities), net Three Months Ended March 31 2024 2023 Beginning balance, January 1 $5 $3 Total net gains (losses) included in changes in net assets (realized/unrealized) 1 (5) Settlements (4) (3) Ending balance, March 31 $2 ($5) 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 March 31 $1 ($5) (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 March 31, 2024 ($1) $8 ($1) $6 $— $2 December 31, 2023 3 21 3 16 — 5 |
Commitments And Contingencies
Commitments And Contingencies | 3 Months Ended |
Mar. 31, 2024 | |
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 battery storage, IPL’s and WPL’s expansion of solar generation, and IPL’s repowering of the existing Franklin County wind farm. At March 31, 2024, Alliant Energy’s, IPL’s and WPL’s minimum future commitments for these projects were $191 million, $80 million and $111 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 March 31, 2024, the related minimum future commitments, excluding amounts for purchased power commitments that do not have minimum thresholds but will require payment when electricity is generated by the provider, were as follows (in millions): Alliant Energy IPL WPL Natural gas $807 $335 $472 Coal 167 110 57 Other (a) 124 52 25 $1,098 $497 $554 (a) Includes individual commitments incurred during the normal course of business that exceeded $1 million at March 31, 2024. 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 March 31, 2024, the currently known partnership obligations for the abandonment obligations are estimated at $49 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 $49 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 and therefore has not recognized any material liabilities related to this guarantee as of March 31, 2024 and December 31, 2023. Whiting Petroleum completed a business combination with Oasis Petroleum Inc. in 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 $51 million as of March 31, 2024 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 March 31, 2024 and December 31, 2023. Transfers of Renewable Tax Credits - In 2023, IPL and WPL entered into agreements to transfer renewable tax credits from certain wind, solar and battery storage facilities to other corporate taxpayers in exchange for cash. IPL and WPL provided indemnifications associated with $76 million and $22 million, respectively, of proceeds for renewable tax credits transferred to other corporate taxpayers in 2023 in the event of an adverse interpretation of tax law, including whether the related tax credits meet the qualification requirements. Alliant Energy, IPL and WPL believe the likelihood of having to make any material cash payments under these indemnifications is remote. 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 March 31, 2024, 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): Alliant Energy IPL WPL Range of estimated future costs $8 - $29 $6 - $18 $2 - $11 Current and non-current environmental liabilities $13 $8 $5 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: Cross-State Air Pollution Rule, 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 the Federal Energy Regulatory Commission (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 2022, the U.S. Court of Appeals for the District of Columbia 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. Any further changes in FERC’s decisions may have an impact on Alliant Energy’s share of ATC’s future earnings and customer costs. NOTE 13(f) Collective Bargaining Agreements - At March 31, 2024, employees covered by collective bargaining agreements represented 53%, 70% and 83% of total employees of Alliant Energy, IPL and WPL, respectively. In August 2024, IPL’s collective bargaining agreement with International Brotherhood of Electrical Workers Local 204 (Cedar Rapids) expires, representing 18% and 53% of total employees of Alliant Energy and IPL, respectively. |
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 battery storage, IPL’s and WPL’s expansion of solar generation, and IPL’s repowering of the existing Franklin County wind farm. At March 31, 2024, Alliant Energy’s, IPL’s and WPL’s minimum future commitments for these projects were $191 million, $80 million and $111 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 March 31, 2024, the related minimum future commitments, excluding amounts for purchased power commitments that do not have minimum thresholds but will require payment when electricity is generated by the provider, were as follows (in millions): Alliant Energy IPL WPL Natural gas $807 $335 $472 Coal 167 110 57 Other (a) 124 52 25 $1,098 $497 $554 (a) Includes individual commitments incurred during the normal course of business that exceeded $1 million at March 31, 2024. 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 March 31, 2024, the currently known partnership obligations for the abandonment obligations are estimated at $49 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 $49 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 and therefore has not recognized any material liabilities related to this guarantee as of March 31, 2024 and December 31, 2023. Whiting Petroleum completed a business combination with Oasis Petroleum Inc. in 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 $51 million as of March 31, 2024 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 March 31, 2024 and December 31, 2023. Transfers of Renewable Tax Credits - In 2023, IPL and WPL entered into agreements to transfer renewable tax credits from certain wind, solar and battery storage facilities to other corporate taxpayers in exchange for cash. IPL and WPL provided indemnifications associated with $76 million and $22 million, respectively, of proceeds for renewable tax credits transferred to other corporate taxpayers in 2023 in the event of an adverse interpretation of tax law, including whether the related tax credits meet the qualification requirements. Alliant Energy, IPL and WPL believe the likelihood of having to make any material cash payments under these indemnifications is remote. 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 March 31, 2024, 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): Alliant Energy IPL WPL Range of estimated future costs $8 - $29 $6 - $18 $2 - $11 Current and non-current environmental liabilities $13 $8 $5 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: Cross-State Air Pollution Rule, 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 the Federal Energy Regulatory Commission (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 2022, the U.S. Court of Appeals for the District of Columbia 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. Any further changes in FERC’s decisions may have an impact on Alliant Energy’s share of ATC’s future earnings and customer costs. NOTE 13(f) Collective Bargaining Agreements - At March 31, 2024, employees covered by collective bargaining agreements represented 53%, 70% and 83% of total employees of Alliant Energy, IPL and WPL, respectively. In August 2024, IPL’s collective bargaining agreement with International Brotherhood of Electrical Workers Local 204 (Cedar Rapids) expires, representing 18% and 53% of total employees of Alliant Energy and IPL, respectively. |
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 battery storage, IPL’s and WPL’s expansion of solar generation, and IPL’s repowering of the existing Franklin County wind farm. At March 31, 2024, Alliant Energy’s, IPL’s and WPL’s minimum future commitments for these projects were $191 million, $80 million and $111 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 March 31, 2024, the related minimum future commitments, excluding amounts for purchased power commitments that do not have minimum thresholds but will require payment when electricity is generated by the provider, were as follows (in millions): Alliant Energy IPL WPL Natural gas $807 $335 $472 Coal 167 110 57 Other (a) 124 52 25 $1,098 $497 $554 (a) Includes individual commitments incurred during the normal course of business that exceeded $1 million at March 31, 2024. 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 March 31, 2024, the currently known partnership obligations for the abandonment obligations are estimated at $49 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 $49 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 and therefore has not recognized any material liabilities related to this guarantee as of March 31, 2024 and December 31, 2023. Whiting Petroleum completed a business combination with Oasis Petroleum Inc. in 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 $51 million as of March 31, 2024 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 March 31, 2024 and December 31, 2023. Transfers of Renewable Tax Credits - In 2023, IPL and WPL entered into agreements to transfer renewable tax credits from certain wind, solar and battery storage facilities to other corporate taxpayers in exchange for cash. IPL and WPL provided indemnifications associated with $76 million and $22 million, respectively, of proceeds for renewable tax credits transferred to other corporate taxpayers in 2023 in the event of an adverse interpretation of tax law, including whether the related tax credits meet the qualification requirements. Alliant Energy, IPL and WPL believe the likelihood of having to make any material cash payments under these indemnifications is remote. 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 March 31, 2024, 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): Alliant Energy IPL WPL Range of estimated future costs $8 - $29 $6 - $18 $2 - $11 Current and non-current environmental liabilities $13 $8 $5 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: Cross-State Air Pollution Rule, 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 the Federal Energy Regulatory Commission (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 2022, the U.S. Court of Appeals for the District of Columbia 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. Any further changes in FERC’s decisions may have an impact on Alliant Energy’s share of ATC’s future earnings and customer costs. NOTE 13(f) Collective Bargaining Agreements - At March 31, 2024, employees covered by collective bargaining agreements represented 53%, 70% and 83% of total employees of Alliant Energy, IPL and WPL, respectively. In August 2024, IPL’s collective bargaining agreement with International Brotherhood of Electrical Workers Local 204 (Cedar Rapids) expires, representing 18% and 53% of total employees of Alliant Energy and IPL, respectively. |
Segments Of Business
Segments Of Business | 3 Months Ended |
Mar. 31, 2024 | |
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 March 31, 2024 Revenues $791 $205 $13 $1,009 $22 $1,031 Operating income 164 47 5 216 6 222 Net income attributable to Alliant Energy common shareowners 155 3 158 Three Months Ended March 31, 2023 Revenues $768 $276 $11 $1,055 $22 $1,077 Operating income 163 50 4 217 5 222 Net income attributable to Alliant Energy common shareowners 160 3 163 IPL Electric Gas Other Total (in millions) Three Months Ended March 31, 2024 Revenues $392 $108 $13 $513 Operating income 57 22 6 85 Net income 63 Three Months Ended March 31, 2023 Revenues $388 $150 $11 $549 Operating income 66 27 3 96 Net income 72 WPL Electric Gas Other Total (in millions) Three Months Ended March 31, 2024 Revenues $399 $97 $— $496 Operating income (loss) 107 25 (1) 131 Net income 92 Three Months Ended March 31, 2023 Revenues $380 $126 $— $506 Operating income 97 23 1 121 Net income 88 |
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 March 31, 2024 Revenues $791 $205 $13 $1,009 $22 $1,031 Operating income 164 47 5 216 6 222 Net income attributable to Alliant Energy common shareowners 155 3 158 Three Months Ended March 31, 2023 Revenues $768 $276 $11 $1,055 $22 $1,077 Operating income 163 50 4 217 5 222 Net income attributable to Alliant Energy common shareowners 160 3 163 IPL Electric Gas Other Total (in millions) Three Months Ended March 31, 2024 Revenues $392 $108 $13 $513 Operating income 57 22 6 85 Net income 63 Three Months Ended March 31, 2023 Revenues $388 $150 $11 $549 Operating income 66 27 3 96 Net income 72 WPL Electric Gas Other Total (in millions) Three Months Ended March 31, 2024 Revenues $399 $97 $— $496 Operating income (loss) 107 25 (1) 131 Net income 92 Three Months Ended March 31, 2023 Revenues $380 $126 $— $506 Operating income 97 23 1 121 Net income 88 |
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 March 31, 2024 Revenues $791 $205 $13 $1,009 $22 $1,031 Operating income 164 47 5 216 6 222 Net income attributable to Alliant Energy common shareowners 155 3 158 Three Months Ended March 31, 2023 Revenues $768 $276 $11 $1,055 $22 $1,077 Operating income 163 50 4 217 5 222 Net income attributable to Alliant Energy common shareowners 160 3 163 IPL Electric Gas Other Total (in millions) Three Months Ended March 31, 2024 Revenues $392 $108 $13 $513 Operating income 57 22 6 85 Net income 63 Three Months Ended March 31, 2023 Revenues $388 $150 $11 $549 Operating income 66 27 3 96 Net income 72 WPL Electric Gas Other Total (in millions) Three Months Ended March 31, 2024 Revenues $399 $97 $— $496 Operating income (loss) 107 25 (1) 131 Net income 92 Three Months Ended March 31, 2023 Revenues $380 $126 $— $506 Operating income 97 23 1 121 Net income 88 |
Related Parties
Related Parties | 3 Months Ended |
Mar. 31, 2024 | |
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 months ended March 31 were as follows (in millions): IPL WPL 2024 2023 2024 2023 Corporate Services billings $43 $40 $40 $36 Sales credited — 7 22 13 Purchases billed 96 93 7 15 Net intercompany payables to Corporate Services were as follows (in millions): IPL WPL March 31, 2024 December 31, 2023 March 31, 2024 December 31, 2023 Net payables to Corporate Services $132 $129 $70 $72 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 months ended March 31 were as follows (in millions): 2024 2023 ATC billings to WPL $37 $34 WPL billings to ATC 3 6 WPL owed ATC net amounts of $10 million as of March 31, 2024 and $10 million as of December 31, 2023. |
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 months ended March 31 were as follows (in millions): IPL WPL 2024 2023 2024 2023 Corporate Services billings $43 $40 $40 $36 Sales credited — 7 22 13 Purchases billed 96 93 7 15 Net intercompany payables to Corporate Services were as follows (in millions): IPL WPL March 31, 2024 December 31, 2023 March 31, 2024 December 31, 2023 Net payables to Corporate Services $132 $129 $70 $72 |
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 months ended March 31 were as follows (in millions): IPL WPL 2024 2023 2024 2023 Corporate Services billings $43 $40 $40 $36 Sales credited — 7 22 13 Purchases billed 96 93 7 15 Net intercompany payables to Corporate Services were as follows (in millions): IPL WPL March 31, 2024 December 31, 2023 March 31, 2024 December 31, 2023 Net payables to Corporate Services $132 $129 $70 $72 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 months ended March 31 were as follows (in millions): 2024 2023 ATC billings to WPL $37 $34 WPL billings to ATC 3 6 WPL owed ATC net amounts of $10 million as of March 31, 2024 and $10 million as of December 31, 2023. |
Pay vs Performance Disclosure
Pay vs Performance Disclosure - USD ($) $ in Millions | 3 Months Ended | |
Mar. 31, 2024 | Mar. 31, 2023 | |
Pay vs Performance Disclosure | ||
Net income | $ 158 | $ 163 |
Insider Trading Arrangements
Insider Trading Arrangements | 3 Months Ended |
Mar. 31, 2024 | |
Trading Arrangements, by Individual | |
Rule 10b5-1 Arrangement Adopted | false |
Non-Rule 10b5-1 Arrangement Adopted | false |
Rule 10b5-1 Arrangement Terminated | false |
Non-Rule 10b5-1 Arrangement Terminated | false |
Summary Of Significant Accoun_2
Summary Of Significant Accounting Policies (Policy) | 3 Months Ended |
Mar. 31, 2024 | |
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 2023 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 three months ended March 31, 2024 are not necessarily indicative of results that may be expected for the year ending December 31, 2024. |
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. |
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 2023 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 three months ended March 31, 2024 are not necessarily indicative of results that may be expected for the year ending December 31, 2024. |
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. |
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 2023 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 three months ended March 31, 2024 are not necessarily indicative of results that may be expected for the year ending December 31, 2024. |
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. |
Regulatory Matters (Tables)
Regulatory Matters (Tables) | 3 Months Ended |
Mar. 31, 2024 | |
Regulatory Assets [Line Items] | |
Regulatory Assets | Regulatory assets were comprised of the following items (in millions): Alliant Energy IPL WPL March 31, December 31, March 31, December 31, March 31, December 31, Tax-related $939 $934 $839 $831 $100 $103 Pension and OPEB costs 340 347 168 171 172 176 Assets retired early 267 273 253 259 14 14 Asset retirement obligations (AROs) 200 194 165 160 35 34 Commodity cost recovery 100 120 5 12 95 108 Derivatives 97 102 33 34 64 68 WPL’s Western Wisconsin gas distribution expansion investments 44 44 — — 44 44 IPL’s Duane Arnold Energy Center PPA amendment 36 42 36 42 — — Other 197 205 68 68 129 137 $2,220 $2,261 $1,567 $1,577 $653 $684 |
Regulatory Liabilities | Regulatory liabilities were comprised of the following items (in millions): Alliant Energy IPL WPL March 31, December 31, March 31, December 31, March 31, December 31, Tax-related $563 $566 $297 $299 $266 $267 Cost of removal obligations 380 366 241 242 139 124 Derivatives 49 65 28 34 21 31 Commodity cost recovery 61 48 25 13 36 35 Other 83 85 57 56 26 29 $1,136 $1,130 $648 $644 $488 $486 |
IPL [Member] | |
Regulatory Assets [Line Items] | |
Regulatory Assets | Regulatory assets were comprised of the following items (in millions): Alliant Energy IPL WPL March 31, December 31, March 31, December 31, March 31, December 31, Tax-related $939 $934 $839 $831 $100 $103 Pension and OPEB costs 340 347 168 171 172 176 Assets retired early 267 273 253 259 14 14 Asset retirement obligations (AROs) 200 194 165 160 35 34 Commodity cost recovery 100 120 5 12 95 108 Derivatives 97 102 33 34 64 68 WPL’s Western Wisconsin gas distribution expansion investments 44 44 — — 44 44 IPL’s Duane Arnold Energy Center PPA amendment 36 42 36 42 — — Other 197 205 68 68 129 137 $2,220 $2,261 $1,567 $1,577 $653 $684 |
Regulatory Liabilities | Regulatory liabilities were comprised of the following items (in millions): Alliant Energy IPL WPL March 31, December 31, March 31, December 31, March 31, December 31, Tax-related $563 $566 $297 $299 $266 $267 Cost of removal obligations 380 366 241 242 139 124 Derivatives 49 65 28 34 21 31 Commodity cost recovery 61 48 25 13 36 35 Other 83 85 57 56 26 29 $1,136 $1,130 $648 $644 $488 $486 |
WPL [Member] | |
Regulatory Assets [Line Items] | |
Regulatory Assets | Regulatory assets were comprised of the following items (in millions): Alliant Energy IPL WPL March 31, December 31, March 31, December 31, March 31, December 31, Tax-related $939 $934 $839 $831 $100 $103 Pension and OPEB costs 340 347 168 171 172 176 Assets retired early 267 273 253 259 14 14 Asset retirement obligations (AROs) 200 194 165 160 35 34 Commodity cost recovery 100 120 5 12 95 108 Derivatives 97 102 33 34 64 68 WPL’s Western Wisconsin gas distribution expansion investments 44 44 — — 44 44 IPL’s Duane Arnold Energy Center PPA amendment 36 42 36 42 — — Other 197 205 68 68 129 137 $2,220 $2,261 $1,567 $1,577 $653 $684 |
Regulatory Liabilities | Regulatory liabilities were comprised of the following items (in millions): Alliant Energy IPL WPL March 31, December 31, March 31, December 31, March 31, December 31, Tax-related $563 $566 $297 $299 $266 $267 Cost of removal obligations 380 366 241 242 139 124 Derivatives 49 65 28 34 21 31 Commodity cost recovery 61 48 25 13 36 35 Other 83 85 57 56 26 29 $1,136 $1,130 $648 $644 $488 $486 |
Receivables (Tables)
Receivables (Tables) | 3 Months Ended |
Mar. 31, 2024 | |
Receivables [Line Items] | |
Maximum And Average Outstanding Cash Proceeds | IPL’s maximum and average outstanding aggregate cash proceeds (based on daily outstanding balances) related to the sales of accounts receivable program for the three months ended March 31 were as follows (in millions): 2024 2023 Maximum outstanding aggregate cash proceeds $79 $89 Average outstanding aggregate cash proceeds 24 58 |
Attributes of Receivables Sold Under the Receivables Agreement | The attributes of IPL’s receivables sold under the Receivables Agreement were as follows (in millions): March 31, 2024 December 31, 2023 Customer accounts receivable $125 $130 Unbilled utility revenues 89 98 Other receivables 1 1 Receivables sold to third party 215 229 Less: cash proceeds 18 1 Deferred proceeds 197 228 Less: allowance for expected credit losses 13 12 Fair value of deferred proceeds $184 $216 |
Additional Attributes Of Receivables Sold Under The Receivables Agreement | Additional attributes of IPL’s receivables sold under the Receivables Agreement for the three months ended March 31 were as follows (in millions): 2024 2023 Collections $557 $591 Write-offs, net of recoveries 3 2 |
IPL [Member] | |
Receivables [Line Items] | |
Maximum And Average Outstanding Cash Proceeds | IPL’s maximum and average outstanding aggregate cash proceeds (based on daily outstanding balances) related to the sales of accounts receivable program for the three months ended March 31 were as follows (in millions): 2024 2023 Maximum outstanding aggregate cash proceeds $79 $89 Average outstanding aggregate cash proceeds 24 58 |
Attributes of Receivables Sold Under the Receivables Agreement | The attributes of IPL’s receivables sold under the Receivables Agreement were as follows (in millions): March 31, 2024 December 31, 2023 Customer accounts receivable $125 $130 Unbilled utility revenues 89 98 Other receivables 1 1 Receivables sold to third party 215 229 Less: cash proceeds 18 1 Deferred proceeds 197 228 Less: allowance for expected credit losses 13 12 Fair value of deferred proceeds $184 $216 |
Additional Attributes Of Receivables Sold Under The Receivables Agreement | Additional attributes of IPL’s receivables sold under the Receivables Agreement for the three months ended March 31 were as follows (in millions): 2024 2023 Collections $557 $591 Write-offs, net of recoveries 3 2 |
Investments (Tables)
Investments (Tables) | 3 Months Ended |
Mar. 31, 2024 | |
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 months ended March 31 was as follows (in millions): 2024 2023 ATC Holdings ($12) ($13) Other (3) (4) ($15) ($17) |
Common Equity (Tables)
Common Equity (Tables) | 3 Months Ended |
Mar. 31, 2024 | |
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, 2024 256,096,848 Shareowner Direct Plan 127,917 Equity-based compensation plans 154,267 Shares outstanding, March 31, 2024 256,379,032 |
Changes in Shareowners' Equity | A summary of changes in shareowners’ equity was as follows (in millions): Alliant Energy Accumulated Shares in Additional Other Deferred Total Common Paid-In Retained Comprehensive Compensation Common Stock Capital Earnings Income (Loss) Trust Equity Three Months Ended March 31, 2024 Beginning balance, December 31, 2023 $3 $3,030 $3,756 $1 ($13) $6,777 Net income attributable to Alliant Energy common shareowners 158 158 Common stock dividends ($0.48 per share) (123) (123) Shareowner Direct Plan issuances 6 6 Equity-based compensation plans and other (3) 1 (2) Other comprehensive income, net of tax 1 1 Ending balance, March 31, 2024 $3 $3,033 $3,791 $2 ($12) $6,817 Three Months Ended March 31, 2023 Beginning balance, December 31, 2022 $3 $2,777 $3,509 $— ($13) $6,276 Net income attributable to Alliant Energy common shareowners 163 163 Common stock dividends ($0.4525 per share) (113) (113) Shareowner Direct Plan issuances 6 6 Equity-based compensation plans and other (3) (3) Other comprehensive loss, net of tax (1) (1) Ending balance, March 31, 2023 $3 $2,780 $3,559 ($1) ($13) $6,328 IPL Additional Total Common Paid-In Retained Common Stock Capital Earnings Equity Three Months Ended March 31, 2024 Beginning balance, December 31, 2023 $33 $2,887 $1,054 $3,974 Net income 63 63 Common stock dividends (50) (50) Capital contributions from parent 50 50 Ending balance, March 31, 2024 $33 $2,937 $1,067 $4,037 Three Months Ended March 31, 2023 Beginning balance, December 31, 2022 $33 $2,807 $968 $3,808 Net income 72 72 Common stock dividends (70) (70) Ending balance, March 31, 2023 $33 $2,807 $970 $3,810 WPL Additional Total Common Paid-In Retained Common Stock Capital Earnings Equity Three Months Ended March 31, 2024 Beginning balance, December 31, 2023 $66 $2,478 $1,353 $3,897 Net income 92 92 Common stock dividends (49) (49) Capital contributions from parent 55 55 Ending balance, March 31, 2024 $66 $2,533 $1,396 $3,995 Three Months Ended March 31, 2023 Beginning balance, December 31, 2022 $66 $2,233 $1,192 $3,491 Net income 88 88 Common stock dividends (46) (46) Capital contributions from parent 180 180 Ending balance, March 31, 2023 $66 $2,413 $1,234 $3,713 |
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 Accumulated Shares in Additional Other Deferred Total Common Paid-In Retained Comprehensive Compensation Common Stock Capital Earnings Income (Loss) Trust Equity Three Months Ended March 31, 2024 Beginning balance, December 31, 2023 $3 $3,030 $3,756 $1 ($13) $6,777 Net income attributable to Alliant Energy common shareowners 158 158 Common stock dividends ($0.48 per share) (123) (123) Shareowner Direct Plan issuances 6 6 Equity-based compensation plans and other (3) 1 (2) Other comprehensive income, net of tax 1 1 Ending balance, March 31, 2024 $3 $3,033 $3,791 $2 ($12) $6,817 Three Months Ended March 31, 2023 Beginning balance, December 31, 2022 $3 $2,777 $3,509 $— ($13) $6,276 Net income attributable to Alliant Energy common shareowners 163 163 Common stock dividends ($0.4525 per share) (113) (113) Shareowner Direct Plan issuances 6 6 Equity-based compensation plans and other (3) (3) Other comprehensive loss, net of tax (1) (1) Ending balance, March 31, 2023 $3 $2,780 $3,559 ($1) ($13) $6,328 IPL Additional Total Common Paid-In Retained Common Stock Capital Earnings Equity Three Months Ended March 31, 2024 Beginning balance, December 31, 2023 $33 $2,887 $1,054 $3,974 Net income 63 63 Common stock dividends (50) (50) Capital contributions from parent 50 50 Ending balance, March 31, 2024 $33 $2,937 $1,067 $4,037 Three Months Ended March 31, 2023 Beginning balance, December 31, 2022 $33 $2,807 $968 $3,808 Net income 72 72 Common stock dividends (70) (70) Ending balance, March 31, 2023 $33 $2,807 $970 $3,810 WPL Additional Total Common Paid-In Retained Common Stock Capital Earnings Equity Three Months Ended March 31, 2024 Beginning balance, December 31, 2023 $66 $2,478 $1,353 $3,897 Net income 92 92 Common stock dividends (49) (49) Capital contributions from parent 55 55 Ending balance, March 31, 2024 $66 $2,533 $1,396 $3,995 Three Months Ended March 31, 2023 Beginning balance, December 31, 2022 $66 $2,233 $1,192 $3,491 Net income 88 88 Common stock dividends (46) (46) Capital contributions from parent 180 180 Ending balance, March 31, 2023 $66 $2,413 $1,234 $3,713 |
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 Accumulated Shares in Additional Other Deferred Total Common Paid-In Retained Comprehensive Compensation Common Stock Capital Earnings Income (Loss) Trust Equity Three Months Ended March 31, 2024 Beginning balance, December 31, 2023 $3 $3,030 $3,756 $1 ($13) $6,777 Net income attributable to Alliant Energy common shareowners 158 158 Common stock dividends ($0.48 per share) (123) (123) Shareowner Direct Plan issuances 6 6 Equity-based compensation plans and other (3) 1 (2) Other comprehensive income, net of tax 1 1 Ending balance, March 31, 2024 $3 $3,033 $3,791 $2 ($12) $6,817 Three Months Ended March 31, 2023 Beginning balance, December 31, 2022 $3 $2,777 $3,509 $— ($13) $6,276 Net income attributable to Alliant Energy common shareowners 163 163 Common stock dividends ($0.4525 per share) (113) (113) Shareowner Direct Plan issuances 6 6 Equity-based compensation plans and other (3) (3) Other comprehensive loss, net of tax (1) (1) Ending balance, March 31, 2023 $3 $2,780 $3,559 ($1) ($13) $6,328 IPL Additional Total Common Paid-In Retained Common Stock Capital Earnings Equity Three Months Ended March 31, 2024 Beginning balance, December 31, 2023 $33 $2,887 $1,054 $3,974 Net income 63 63 Common stock dividends (50) (50) Capital contributions from parent 50 50 Ending balance, March 31, 2024 $33 $2,937 $1,067 $4,037 Three Months Ended March 31, 2023 Beginning balance, December 31, 2022 $33 $2,807 $968 $3,808 Net income 72 72 Common stock dividends (70) (70) Ending balance, March 31, 2023 $33 $2,807 $970 $3,810 WPL Additional Total Common Paid-In Retained Common Stock Capital Earnings Equity Three Months Ended March 31, 2024 Beginning balance, December 31, 2023 $66 $2,478 $1,353 $3,897 Net income 92 92 Common stock dividends (49) (49) Capital contributions from parent 55 55 Ending balance, March 31, 2024 $66 $2,533 $1,396 $3,995 Three Months Ended March 31, 2023 Beginning balance, December 31, 2022 $66 $2,233 $1,192 $3,491 Net income 88 88 Common stock dividends (46) (46) Capital contributions from parent 180 180 Ending balance, March 31, 2023 $66 $2,413 $1,234 $3,713 |
Debt (Tables)
Debt (Tables) | 3 Months Ended |
Mar. 31, 2024 | |
Short-term Debt [Line Items] | |
Other Short-Term Borrowings | Information regarding commercial paper classified as short-term debt was as follows (dollars in millions): March 31, 2024 Alliant Energy IPL WPL Amount outstanding $334 $— $— Weighted average interest rates 5.5% —% —% Available credit facility capacity $666 $200 $300 Alliant Energy IPL WPL Three Months Ended March 31 2024 2023 2024 2023 2024 2023 Maximum amount outstanding (based on daily outstanding balances) $632 $793 $14 $— $390 $349 Average amount outstanding (based on daily outstanding balances) $487 $574 $1 $— $255 $304 Weighted average interest rates 5.5% 4.8% 5.5% —% 5.5% 4.8% |
IPL [Member] | |
Short-term Debt [Line Items] | |
Other Short-Term Borrowings | Information regarding commercial paper classified as short-term debt was as follows (dollars in millions): March 31, 2024 Alliant Energy IPL WPL Amount outstanding $334 $— $— Weighted average interest rates 5.5% —% —% Available credit facility capacity $666 $200 $300 Alliant Energy IPL WPL Three Months Ended March 31 2024 2023 2024 2023 2024 2023 Maximum amount outstanding (based on daily outstanding balances) $632 $793 $14 $— $390 $349 Average amount outstanding (based on daily outstanding balances) $487 $574 $1 $— $255 $304 Weighted average interest rates 5.5% 4.8% 5.5% —% 5.5% 4.8% |
WPL [Member] | |
Short-term Debt [Line Items] | |
Other Short-Term Borrowings | Information regarding commercial paper classified as short-term debt was as follows (dollars in millions): March 31, 2024 Alliant Energy IPL WPL Amount outstanding $334 $— $— Weighted average interest rates 5.5% —% —% Available credit facility capacity $666 $200 $300 Alliant Energy IPL WPL Three Months Ended March 31 2024 2023 2024 2023 2024 2023 Maximum amount outstanding (based on daily outstanding balances) $632 $793 $14 $— $390 $349 Average amount outstanding (based on daily outstanding balances) $487 $574 $1 $— $255 $304 Weighted average interest rates 5.5% 4.8% 5.5% —% 5.5% 4.8% |
Revenues (Tables)
Revenues (Tables) | 3 Months Ended |
Mar. 31, 2024 | |
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 March 31 2024 2023 2024 2023 2024 2023 Electric Utility: Retail - residential $297 $285 $150 $143 $147 $142 Retail - commercial 186 185 114 112 72 73 Retail - industrial 223 216 112 107 111 109 Wholesale 47 46 13 12 34 34 Bulk power and other 38 36 3 14 35 22 Total Electric Utility 791 768 392 388 399 380 Gas Utility: Retail - residential 126 167 68 93 58 74 Retail - commercial 61 88 30 44 31 44 Retail - industrial 5 7 3 4 2 3 Transportation/other 13 14 7 9 6 5 Total Gas Utility 205 276 108 150 97 126 Other Utility: Steam 12 10 12 10 — — Other utility 1 1 1 1 — — Total Other Utility 13 11 13 11 — — Non-Utility and Other: Travero and other 22 22 — — — — Total Non-Utility and Other 22 22 — — — — Total revenues $1,031 $1,077 $513 $549 $496 $506 |
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 March 31 2024 2023 2024 2023 2024 2023 Electric Utility: Retail - residential $297 $285 $150 $143 $147 $142 Retail - commercial 186 185 114 112 72 73 Retail - industrial 223 216 112 107 111 109 Wholesale 47 46 13 12 34 34 Bulk power and other 38 36 3 14 35 22 Total Electric Utility 791 768 392 388 399 380 Gas Utility: Retail - residential 126 167 68 93 58 74 Retail - commercial 61 88 30 44 31 44 Retail - industrial 5 7 3 4 2 3 Transportation/other 13 14 7 9 6 5 Total Gas Utility 205 276 108 150 97 126 Other Utility: Steam 12 10 12 10 — — Other utility 1 1 1 1 — — Total Other Utility 13 11 13 11 — — Non-Utility and Other: Travero and other 22 22 — — — — Total Non-Utility and Other 22 22 — — — — Total revenues $1,031 $1,077 $513 $549 $496 $506 |
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 March 31 2024 2023 2024 2023 2024 2023 Electric Utility: Retail - residential $297 $285 $150 $143 $147 $142 Retail - commercial 186 185 114 112 72 73 Retail - industrial 223 216 112 107 111 109 Wholesale 47 46 13 12 34 34 Bulk power and other 38 36 3 14 35 22 Total Electric Utility 791 768 392 388 399 380 Gas Utility: Retail - residential 126 167 68 93 58 74 Retail - commercial 61 88 30 44 31 44 Retail - industrial 5 7 3 4 2 3 Transportation/other 13 14 7 9 6 5 Total Gas Utility 205 276 108 150 97 126 Other Utility: Steam 12 10 12 10 — — Other utility 1 1 1 1 — — Total Other Utility 13 11 13 11 — — Non-Utility and Other: Travero and other 22 22 — — — — Total Non-Utility and Other 22 22 — — — — Total revenues $1,031 $1,077 $513 $549 $496 $506 |
Income Taxes (Tables)
Income Taxes (Tables) | 3 Months Ended |
Mar. 31, 2024 | |
Income Taxes [Line Items] | |
Schedule Of Effective Income Tax Rates | Overall effective income tax rates for the three months ended March 31, 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. Alliant Energy IPL WPL 2024 2023 2024 2023 2024 2023 Overall income tax rate (7%) (1%) (19%) (18%) 6% 12% |
Summary Of Tax Credit Carryforwards | At March 31, 2024, the carryforwards and expiration dates were estimated as follows (in millions): Range of Expiration Dates Alliant Energy IPL WPL State net operating losses 2025-2044 $403 $6 $1 Federal tax credits 2032-2044 685 462 214 |
IPL [Member] | |
Income Taxes [Line Items] | |
Schedule Of Effective Income Tax Rates | Overall effective income tax rates for the three months ended March 31, 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. Alliant Energy IPL WPL 2024 2023 2024 2023 2024 2023 Overall income tax rate (7%) (1%) (19%) (18%) 6% 12% |
Summary Of Tax Credit Carryforwards | At March 31, 2024, the carryforwards and expiration dates were estimated as follows (in millions): Range of Expiration Dates Alliant Energy IPL WPL State net operating losses 2025-2044 $403 $6 $1 Federal tax credits 2032-2044 685 462 214 |
WPL [Member] | |
Income Taxes [Line Items] | |
Schedule Of Effective Income Tax Rates | Overall effective income tax rates for the three months ended March 31, 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. Alliant Energy IPL WPL 2024 2023 2024 2023 2024 2023 Overall income tax rate (7%) (1%) (19%) (18%) 6% 12% |
Summary Of Tax Credit Carryforwards | At March 31, 2024, the carryforwards and expiration dates were estimated as follows (in millions): Range of Expiration Dates Alliant Energy IPL WPL State net operating losses 2025-2044 $403 $6 $1 Federal tax credits 2032-2044 685 462 214 |
Benefit Plans (Tables)
Benefit Plans (Tables) | 3 Months Ended |
Mar. 31, 2024 | |
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 months ended March 31 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 Alliant Energy 2024 2023 2024 2023 Service cost $1 $1 $— $1 Interest cost 11 11 2 2 Expected return on plan assets (13) (13) (1) (1) Amortization of actuarial loss 6 7 — — $5 $6 $1 $2 Defined Benefit Pension Plans OPEB Plans IPL 2024 2023 2024 2023 Service cost $1 $1 $— $— Interest cost 5 5 1 1 Expected return on plan assets (7) (7) (1) (1) Amortization of actuarial loss 2 3 — — $1 $2 $— $— Defined Benefit Pension Plans OPEB Plans WPL 2024 2023 2024 2023 Interest cost $5 $5 $1 $1 Expected return on plan assets (6) (5) — — Amortization of actuarial loss 3 3 — — $2 $3 $1 $1 |
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 months ended March 31 was as follows (in millions): Alliant Energy IPL WPL 2024 2023 2024 2023 2024 2023 Compensation expense $4 $3 $2 $2 $2 $1 Income tax benefits 1 1 1 — — — |
Schedule Of Equity-based Compensation Plans Activity | For the three months ended March 31, 2024, performance shares and restricted stock units were granted to key employees under the equity-based compensation 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 (total shareowner return metric) 123,098 $46.04 Performance shares (net income and diversity metrics) (formerly granted as performance restricted stock units) 140,683 48.40 Restricted stock units 120,557 48.40 |
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 months ended March 31 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 Alliant Energy 2024 2023 2024 2023 Service cost $1 $1 $— $1 Interest cost 11 11 2 2 Expected return on plan assets (13) (13) (1) (1) Amortization of actuarial loss 6 7 — — $5 $6 $1 $2 Defined Benefit Pension Plans OPEB Plans IPL 2024 2023 2024 2023 Service cost $1 $1 $— $— Interest cost 5 5 1 1 Expected return on plan assets (7) (7) (1) (1) Amortization of actuarial loss 2 3 — — $1 $2 $— $— Defined Benefit Pension Plans OPEB Plans WPL 2024 2023 2024 2023 Interest cost $5 $5 $1 $1 Expected return on plan assets (6) (5) — — Amortization of actuarial loss 3 3 — — $2 $3 $1 $1 |
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 months ended March 31 was as follows (in millions): Alliant Energy IPL WPL 2024 2023 2024 2023 2024 2023 Compensation expense $4 $3 $2 $2 $2 $1 Income tax benefits 1 1 1 — — — |
Schedule Of Equity-based Compensation Plans Activity | For the three months ended March 31, 2024, performance shares and restricted stock units were granted to key employees under the equity-based compensation 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 (total shareowner return metric) 123,098 $46.04 Performance shares (net income and diversity metrics) (formerly granted as performance restricted stock units) 140,683 48.40 Restricted stock units 120,557 48.40 |
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 months ended March 31 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 Alliant Energy 2024 2023 2024 2023 Service cost $1 $1 $— $1 Interest cost 11 11 2 2 Expected return on plan assets (13) (13) (1) (1) Amortization of actuarial loss 6 7 — — $5 $6 $1 $2 Defined Benefit Pension Plans OPEB Plans IPL 2024 2023 2024 2023 Service cost $1 $1 $— $— Interest cost 5 5 1 1 Expected return on plan assets (7) (7) (1) (1) Amortization of actuarial loss 2 3 — — $1 $2 $— $— Defined Benefit Pension Plans OPEB Plans WPL 2024 2023 2024 2023 Interest cost $5 $5 $1 $1 Expected return on plan assets (6) (5) — — Amortization of actuarial loss 3 3 — — $2 $3 $1 $1 |
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 months ended March 31 was as follows (in millions): Alliant Energy IPL WPL 2024 2023 2024 2023 2024 2023 Compensation expense $4 $3 $2 $2 $2 $1 Income tax benefits 1 1 1 — — — |
Schedule Of Equity-based Compensation Plans Activity | For the three months ended March 31, 2024, performance shares and restricted stock units were granted to key employees under the equity-based compensation 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 (total shareowner return metric) 123,098 $46.04 Performance shares (net income and diversity metrics) (formerly granted as performance restricted stock units) 140,683 48.40 Restricted stock units 120,557 48.40 |
Derivative Instruments (Tables)
Derivative Instruments (Tables) | 3 Months Ended |
Mar. 31, 2024 | |
Derivative Instruments [Line Items] | |
Notional Amounts Of Derivative Instruments | As of March 31, 2024, 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 MWhs Years MWhs Years Dths Years Alliant Energy 1,412 2024-2026 4,162 2024 173,746 2024-2032 IPL 673 2024-2026 1,444 2024 78,790 2024-2030 WPL 739 2024-2026 2,718 2024 94,956 2024-2032 |
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 March 31, December 31, March 31, December 31, March 31, December 31, Current derivative assets $16 $44 $12 $30 $4 $14 Non-current derivative assets 40 44 22 24 18 20 Current derivative liabilities 49 51 23 22 26 29 Non-current derivative liabilities 45 47 7 8 38 39 |
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 March 31, 2024 Derivative assets $56 $26 $34 $17 $22 $9 Derivative liabilities 94 64 30 13 64 51 December 31, 2023 Derivative assets 88 47 54 32 34 15 Derivative liabilities 98 57 30 8 68 49 |
IPL [Member] | |
Derivative Instruments [Line Items] | |
Notional Amounts Of Derivative Instruments | As of March 31, 2024, 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 MWhs Years MWhs Years Dths Years Alliant Energy 1,412 2024-2026 4,162 2024 173,746 2024-2032 IPL 673 2024-2026 1,444 2024 78,790 2024-2030 WPL 739 2024-2026 2,718 2024 94,956 2024-2032 |
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 March 31, December 31, March 31, December 31, March 31, December 31, Current derivative assets $16 $44 $12 $30 $4 $14 Non-current derivative assets 40 44 22 24 18 20 Current derivative liabilities 49 51 23 22 26 29 Non-current derivative liabilities 45 47 7 8 38 39 |
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 March 31, 2024 Derivative assets $56 $26 $34 $17 $22 $9 Derivative liabilities 94 64 30 13 64 51 December 31, 2023 Derivative assets 88 47 54 32 34 15 Derivative liabilities 98 57 30 8 68 49 |
WPL [Member] | |
Derivative Instruments [Line Items] | |
Notional Amounts Of Derivative Instruments | As of March 31, 2024, 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 MWhs Years MWhs Years Dths Years Alliant Energy 1,412 2024-2026 4,162 2024 173,746 2024-2032 IPL 673 2024-2026 1,444 2024 78,790 2024-2030 WPL 739 2024-2026 2,718 2024 94,956 2024-2032 |
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 March 31, December 31, March 31, December 31, March 31, December 31, Current derivative assets $16 $44 $12 $30 $4 $14 Non-current derivative assets 40 44 22 24 18 20 Current derivative liabilities 49 51 23 22 26 29 Non-current derivative liabilities 45 47 7 8 38 39 |
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 March 31, 2024 Derivative assets $56 $26 $34 $17 $22 $9 Derivative liabilities 94 64 30 13 64 51 December 31, 2023 Derivative assets 88 47 54 32 34 15 Derivative liabilities 98 57 30 8 68 49 |
Fair Value Measurements (Tables
Fair Value Measurements (Tables) | 3 Months Ended |
Mar. 31, 2024 | |
Statement [Line Items] | |
Fair Value Measurements | Carrying amounts and related estimated fair values of other financial instruments were as follows (in millions): Alliant Energy March 31, 2024 December 31, 2023 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 $10 $10 $— $— $10 $45 $45 $— $— $45 Commodity derivatives 56 — 46 10 56 88 — 59 29 88 Interest rate derivatives 3 — 3 — 3 1 — 1 — 1 Deferred proceeds 184 — — 184 184 216 — — 216 216 Liabilities: Commodity derivatives 94 — 91 3 94 98 — 93 5 98 Long-term debt (incl. current maturities) 9,333 — 9,051 — 9,051 9,034 — 8,677 — 8,677 IPL March 31, 2024 December 31, 2023 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 $6 $6 $— $— $6 $45 $45 $— $— $45 Commodity derivatives 34 — 26 8 34 54 — 30 24 54 Deferred proceeds 184 — — 184 184 216 — — 216 216 Liabilities: Commodity derivatives 30 — 27 3 30 30 — 25 5 30 Long-term debt (incl. current maturities) 3,945 — 3,607 — 3,607 3,945 — 3,664 — 3,664 WPL March 31, 2024 December 31, 2023 Fair Value Fair Value Carrying Level Level Level Carrying Level Level Level Amount 1 2 3 Total Amount 1 2 3 Total Assets: Commodity derivatives $22 $— $20 $2 $22 $34 $— $29 $5 $34 Liabilities: Commodity derivatives 64 — 64 — 64 68 — 68 — 68 Long-term debt 3,367 — 3,176 — 3,176 3,070 — 2,933 — 2,933 |
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 March 31 2024 2023 2024 2023 Beginning balance, January 1 $24 $19 $216 $185 Total net losses included in changes in net assets (realized/unrealized) (3) (4) — — Settlements (a) (14) (20) (32) (32) Ending balance, March 31 $7 ($5) $184 $153 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 March 31 ($3) ($4) $— $— IPL Commodity Contract Derivative Assets and (Liabilities), net Deferred Proceeds Three Months Ended March 31 2024 2023 2024 2023 Beginning balance, January 1 $19 $16 $216 $185 Total net gains (losses) included in changes in net assets (realized/unrealized) (4) 1 — — Settlements (a) (10) (17) (32) (32) Ending balance, March 31 $5 $— $184 $153 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 March 31 ($4) $1 $— $— WPL Commodity Contract Derivative Assets and (Liabilities), net Three Months Ended March 31 2024 2023 Beginning balance, January 1 $5 $3 Total net gains (losses) included in changes in net assets (realized/unrealized) 1 (5) Settlements (4) (3) Ending balance, March 31 $2 ($5) 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 March 31 $1 ($5) (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 March 31, 2024 ($1) $8 ($1) $6 $— $2 December 31, 2023 3 21 3 16 — 5 |
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 March 31, 2024 December 31, 2023 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 $10 $10 $— $— $10 $45 $45 $— $— $45 Commodity derivatives 56 — 46 10 56 88 — 59 29 88 Interest rate derivatives 3 — 3 — 3 1 — 1 — 1 Deferred proceeds 184 — — 184 184 216 — — 216 216 Liabilities: Commodity derivatives 94 — 91 3 94 98 — 93 5 98 Long-term debt (incl. current maturities) 9,333 — 9,051 — 9,051 9,034 — 8,677 — 8,677 IPL March 31, 2024 December 31, 2023 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 $6 $6 $— $— $6 $45 $45 $— $— $45 Commodity derivatives 34 — 26 8 34 54 — 30 24 54 Deferred proceeds 184 — — 184 184 216 — — 216 216 Liabilities: Commodity derivatives 30 — 27 3 30 30 — 25 5 30 Long-term debt (incl. current maturities) 3,945 — 3,607 — 3,607 3,945 — 3,664 — 3,664 WPL March 31, 2024 December 31, 2023 Fair Value Fair Value Carrying Level Level Level Carrying Level Level Level Amount 1 2 3 Total Amount 1 2 3 Total Assets: Commodity derivatives $22 $— $20 $2 $22 $34 $— $29 $5 $34 Liabilities: Commodity derivatives 64 — 64 — 64 68 — 68 — 68 Long-term debt 3,367 — 3,176 — 3,176 3,070 — 2,933 — 2,933 |
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 March 31 2024 2023 2024 2023 Beginning balance, January 1 $24 $19 $216 $185 Total net losses included in changes in net assets (realized/unrealized) (3) (4) — — Settlements (a) (14) (20) (32) (32) Ending balance, March 31 $7 ($5) $184 $153 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 March 31 ($3) ($4) $— $— IPL Commodity Contract Derivative Assets and (Liabilities), net Deferred Proceeds Three Months Ended March 31 2024 2023 2024 2023 Beginning balance, January 1 $19 $16 $216 $185 Total net gains (losses) included in changes in net assets (realized/unrealized) (4) 1 — — Settlements (a) (10) (17) (32) (32) Ending balance, March 31 $5 $— $184 $153 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 March 31 ($4) $1 $— $— WPL Commodity Contract Derivative Assets and (Liabilities), net Three Months Ended March 31 2024 2023 Beginning balance, January 1 $5 $3 Total net gains (losses) included in changes in net assets (realized/unrealized) 1 (5) Settlements (4) (3) Ending balance, March 31 $2 ($5) 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 March 31 $1 ($5) (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 March 31, 2024 ($1) $8 ($1) $6 $— $2 December 31, 2023 3 21 3 16 — 5 |
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 March 31, 2024 December 31, 2023 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 $10 $10 $— $— $10 $45 $45 $— $— $45 Commodity derivatives 56 — 46 10 56 88 — 59 29 88 Interest rate derivatives 3 — 3 — 3 1 — 1 — 1 Deferred proceeds 184 — — 184 184 216 — — 216 216 Liabilities: Commodity derivatives 94 — 91 3 94 98 — 93 5 98 Long-term debt (incl. current maturities) 9,333 — 9,051 — 9,051 9,034 — 8,677 — 8,677 IPL March 31, 2024 December 31, 2023 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 $6 $6 $— $— $6 $45 $45 $— $— $45 Commodity derivatives 34 — 26 8 34 54 — 30 24 54 Deferred proceeds 184 — — 184 184 216 — — 216 216 Liabilities: Commodity derivatives 30 — 27 3 30 30 — 25 5 30 Long-term debt (incl. current maturities) 3,945 — 3,607 — 3,607 3,945 — 3,664 — 3,664 WPL March 31, 2024 December 31, 2023 Fair Value Fair Value Carrying Level Level Level Carrying Level Level Level Amount 1 2 3 Total Amount 1 2 3 Total Assets: Commodity derivatives $22 $— $20 $2 $22 $34 $— $29 $5 $34 Liabilities: Commodity derivatives 64 — 64 — 64 68 — 68 — 68 Long-term debt 3,367 — 3,176 — 3,176 3,070 — 2,933 — 2,933 |
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 March 31 2024 2023 2024 2023 Beginning balance, January 1 $24 $19 $216 $185 Total net losses included in changes in net assets (realized/unrealized) (3) (4) — — Settlements (a) (14) (20) (32) (32) Ending balance, March 31 $7 ($5) $184 $153 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 March 31 ($3) ($4) $— $— IPL Commodity Contract Derivative Assets and (Liabilities), net Deferred Proceeds Three Months Ended March 31 2024 2023 2024 2023 Beginning balance, January 1 $19 $16 $216 $185 Total net gains (losses) included in changes in net assets (realized/unrealized) (4) 1 — — Settlements (a) (10) (17) (32) (32) Ending balance, March 31 $5 $— $184 $153 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 March 31 ($4) $1 $— $— WPL Commodity Contract Derivative Assets and (Liabilities), net Three Months Ended March 31 2024 2023 Beginning balance, January 1 $5 $3 Total net gains (losses) included in changes in net assets (realized/unrealized) 1 (5) Settlements (4) (3) Ending balance, March 31 $2 ($5) 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 March 31 $1 ($5) (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 March 31, 2024 ($1) $8 ($1) $6 $— $2 December 31, 2023 3 21 3 16 — 5 |
Commitments And Contingencies (
Commitments And Contingencies (Tables) | 3 Months Ended |
Mar. 31, 2024 | |
Commitments and Contingencies [Line Items] | |
Other Purchase Commitments | At March 31, 2024, the related minimum future commitments, excluding amounts for purchased power commitments that do not have minimum thresholds but will require payment when electricity is generated by the provider, were as follows (in millions): Alliant Energy IPL WPL Natural gas $807 $335 $472 Coal 167 110 57 Other (a) 124 52 25 $1,098 $497 $554 (a) Includes individual commitments incurred during the normal course of business that exceeded $1 million at March 31, 2024. |
MGP Site Estimated Future Costs And Recorded Liabilities | At March 31, 2024, 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): Alliant Energy IPL WPL Range of estimated future costs $8 - $29 $6 - $18 $2 - $11 Current and non-current environmental liabilities $13 $8 $5 |
IPL [Member] | |
Commitments and Contingencies [Line Items] | |
Other Purchase Commitments | At March 31, 2024, the related minimum future commitments, excluding amounts for purchased power commitments that do not have minimum thresholds but will require payment when electricity is generated by the provider, were as follows (in millions): Alliant Energy IPL WPL Natural gas $807 $335 $472 Coal 167 110 57 Other (a) 124 52 25 $1,098 $497 $554 (a) Includes individual commitments incurred during the normal course of business that exceeded $1 million at March 31, 2024. |
MGP Site Estimated Future Costs And Recorded Liabilities | At March 31, 2024, 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): Alliant Energy IPL WPL Range of estimated future costs $8 - $29 $6 - $18 $2 - $11 Current and non-current environmental liabilities $13 $8 $5 |
WPL [Member] | |
Commitments and Contingencies [Line Items] | |
Other Purchase Commitments | At March 31, 2024, the related minimum future commitments, excluding amounts for purchased power commitments that do not have minimum thresholds but will require payment when electricity is generated by the provider, were as follows (in millions): Alliant Energy IPL WPL Natural gas $807 $335 $472 Coal 167 110 57 Other (a) 124 52 25 $1,098 $497 $554 (a) Includes individual commitments incurred during the normal course of business that exceeded $1 million at March 31, 2024. |
MGP Site Estimated Future Costs And Recorded Liabilities | At March 31, 2024, 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): Alliant Energy IPL WPL Range of estimated future costs $8 - $29 $6 - $18 $2 - $11 Current and non-current environmental liabilities $13 $8 $5 |
Segments Of Business (Tables)
Segments Of Business (Tables) | 3 Months Ended |
Mar. 31, 2024 | |
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 March 31, 2024 Revenues $791 $205 $13 $1,009 $22 $1,031 Operating income 164 47 5 216 6 222 Net income attributable to Alliant Energy common shareowners 155 3 158 Three Months Ended March 31, 2023 Revenues $768 $276 $11 $1,055 $22 $1,077 Operating income 163 50 4 217 5 222 Net income attributable to Alliant Energy common shareowners 160 3 163 IPL Electric Gas Other Total (in millions) Three Months Ended March 31, 2024 Revenues $392 $108 $13 $513 Operating income 57 22 6 85 Net income 63 Three Months Ended March 31, 2023 Revenues $388 $150 $11 $549 Operating income 66 27 3 96 Net income 72 WPL Electric Gas Other Total (in millions) Three Months Ended March 31, 2024 Revenues $399 $97 $— $496 Operating income (loss) 107 25 (1) 131 Net income 92 Three Months Ended March 31, 2023 Revenues $380 $126 $— $506 Operating income 97 23 1 121 Net income 88 |
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 March 31, 2024 Revenues $791 $205 $13 $1,009 $22 $1,031 Operating income 164 47 5 216 6 222 Net income attributable to Alliant Energy common shareowners 155 3 158 Three Months Ended March 31, 2023 Revenues $768 $276 $11 $1,055 $22 $1,077 Operating income 163 50 4 217 5 222 Net income attributable to Alliant Energy common shareowners 160 3 163 IPL Electric Gas Other Total (in millions) Three Months Ended March 31, 2024 Revenues $392 $108 $13 $513 Operating income 57 22 6 85 Net income 63 Three Months Ended March 31, 2023 Revenues $388 $150 $11 $549 Operating income 66 27 3 96 Net income 72 WPL Electric Gas Other Total (in millions) Three Months Ended March 31, 2024 Revenues $399 $97 $— $496 Operating income (loss) 107 25 (1) 131 Net income 92 Three Months Ended March 31, 2023 Revenues $380 $126 $— $506 Operating income 97 23 1 121 Net income 88 |
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 March 31, 2024 Revenues $791 $205 $13 $1,009 $22 $1,031 Operating income 164 47 5 216 6 222 Net income attributable to Alliant Energy common shareowners 155 3 158 Three Months Ended March 31, 2023 Revenues $768 $276 $11 $1,055 $22 $1,077 Operating income 163 50 4 217 5 222 Net income attributable to Alliant Energy common shareowners 160 3 163 IPL Electric Gas Other Total (in millions) Three Months Ended March 31, 2024 Revenues $392 $108 $13 $513 Operating income 57 22 6 85 Net income 63 Three Months Ended March 31, 2023 Revenues $388 $150 $11 $549 Operating income 66 27 3 96 Net income 72 WPL Electric Gas Other Total (in millions) Three Months Ended March 31, 2024 Revenues $399 $97 $— $496 Operating income (loss) 107 25 (1) 131 Net income 92 Three Months Ended March 31, 2023 Revenues $380 $126 $— $506 Operating income 97 23 1 121 Net income 88 |
Related Parties (Tables)
Related Parties (Tables) | 3 Months Ended |
Mar. 31, 2024 | |
Related Party Transactions [Line Items] | |
Services Provided, Sales Credited And Purchases | The amounts billed for services provided, sales credited and purchases for the three months ended March 31 were as follows (in millions): IPL WPL 2024 2023 2024 2023 Corporate Services billings $43 $40 $40 $36 Sales credited — 7 22 13 Purchases billed 96 93 7 15 |
Net Intercompany Payables | Net intercompany payables to Corporate Services were as follows (in millions): IPL WPL March 31, 2024 December 31, 2023 March 31, 2024 December 31, 2023 Net payables to Corporate Services $132 $129 $70 $72 |
Related Amounts Billed Between Parties | The related amounts billed between the parties for the three months ended March 31 were as follows (in millions): 2024 2023 ATC billings to WPL $37 $34 WPL billings to ATC 3 6 |
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 months ended March 31 were as follows (in millions): IPL WPL 2024 2023 2024 2023 Corporate Services billings $43 $40 $40 $36 Sales credited — 7 22 13 Purchases billed 96 93 7 15 |
Net Intercompany Payables | Net intercompany payables to Corporate Services were as follows (in millions): IPL WPL March 31, 2024 December 31, 2023 March 31, 2024 December 31, 2023 Net payables to Corporate Services $132 $129 $70 $72 |
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 months ended March 31 were as follows (in millions): IPL WPL 2024 2023 2024 2023 Corporate Services billings $43 $40 $40 $36 Sales credited — 7 22 13 Purchases billed 96 93 7 15 |
Net Intercompany Payables | Net intercompany payables to Corporate Services were as follows (in millions): IPL WPL March 31, 2024 December 31, 2023 March 31, 2024 December 31, 2023 Net payables to Corporate Services $132 $129 $70 $72 |
Related Amounts Billed Between Parties | The related amounts billed between the parties for the three months ended March 31 were as follows (in millions): 2024 2023 ATC billings to WPL $37 $34 WPL billings to ATC 3 6 |
Regulatory Matters (Regulatory
Regulatory Matters (Regulatory Assets) (Details) - USD ($) $ in Millions | Mar. 31, 2024 | Dec. 31, 2023 |
Regulatory Assets [Line Items] | ||
Regulatory assets | $ 2,220 | $ 2,261 |
Tax-related [Member] | ||
Regulatory Assets [Line Items] | ||
Regulatory assets | 939 | 934 |
Pension and OPEB costs [Member] | ||
Regulatory Assets [Line Items] | ||
Regulatory assets | 340 | 347 |
Assets retired early [Member] | ||
Regulatory Assets [Line Items] | ||
Regulatory assets | 267 | 273 |
Asset retirement obligations [Member] | ||
Regulatory Assets [Line Items] | ||
Regulatory assets | 200 | 194 |
Commodity cost recovery [Member] | ||
Regulatory Assets [Line Items] | ||
Regulatory assets | 100 | 120 |
Derivatives [Member] | ||
Regulatory Assets [Line Items] | ||
Regulatory assets | 97 | 102 |
WPL's Western Wisconsin gas distribution expansion investments [Member] | ||
Regulatory Assets [Line Items] | ||
Regulatory assets | 44 | 44 |
IPL's Duane Arnold Energy Center PPA amendment [Member] | ||
Regulatory Assets [Line Items] | ||
Regulatory assets | 36 | 42 |
Other [Member] | ||
Regulatory Assets [Line Items] | ||
Regulatory assets | 197 | 205 |
IPL [Member] | ||
Regulatory Assets [Line Items] | ||
Regulatory assets | 1,567 | 1,577 |
IPL [Member] | Tax-related [Member] | ||
Regulatory Assets [Line Items] | ||
Regulatory assets | 839 | 831 |
IPL [Member] | Pension and OPEB costs [Member] | ||
Regulatory Assets [Line Items] | ||
Regulatory assets | 168 | 171 |
IPL [Member] | Assets retired early [Member] | ||
Regulatory Assets [Line Items] | ||
Regulatory assets | 253 | 259 |
IPL [Member] | Asset retirement obligations [Member] | ||
Regulatory Assets [Line Items] | ||
Regulatory assets | 165 | 160 |
IPL [Member] | Commodity cost recovery [Member] | ||
Regulatory Assets [Line Items] | ||
Regulatory assets | 5 | 12 |
IPL [Member] | Derivatives [Member] | ||
Regulatory Assets [Line Items] | ||
Regulatory assets | 33 | 34 |
IPL [Member] | IPL's Duane Arnold Energy Center PPA amendment [Member] | ||
Regulatory Assets [Line Items] | ||
Regulatory assets | 36 | 42 |
IPL [Member] | Other [Member] | ||
Regulatory Assets [Line Items] | ||
Regulatory assets | 68 | 68 |
WPL [Member] | ||
Regulatory Assets [Line Items] | ||
Regulatory assets | 653 | 684 |
WPL [Member] | Tax-related [Member] | ||
Regulatory Assets [Line Items] | ||
Regulatory assets | 100 | 103 |
WPL [Member] | Pension and OPEB costs [Member] | ||
Regulatory Assets [Line Items] | ||
Regulatory assets | 172 | 176 |
WPL [Member] | Assets retired early [Member] | ||
Regulatory Assets [Line Items] | ||
Regulatory assets | 14 | 14 |
WPL [Member] | Asset retirement obligations [Member] | ||
Regulatory Assets [Line Items] | ||
Regulatory assets | 35 | 34 |
WPL [Member] | Commodity cost recovery [Member] | ||
Regulatory Assets [Line Items] | ||
Regulatory assets | 95 | 108 |
WPL [Member] | Derivatives [Member] | ||
Regulatory Assets [Line Items] | ||
Regulatory assets | 64 | 68 |
WPL [Member] | WPL's Western Wisconsin gas distribution expansion investments [Member] | ||
Regulatory Assets [Line Items] | ||
Regulatory assets | 44 | 44 |
WPL [Member] | Other [Member] | ||
Regulatory Assets [Line Items] | ||
Regulatory assets | $ 129 | $ 137 |
Regulatory Matters (Regulator_2
Regulatory Matters (Regulatory Liabilities) (Details) - USD ($) $ in Millions | Mar. 31, 2024 | Dec. 31, 2023 |
Regulatory Liabilities [Line Items] | ||
Regulatory liabilities | $ 1,136 | $ 1,130 |
Tax-related [Member] | ||
Regulatory Liabilities [Line Items] | ||
Regulatory liabilities | 563 | 566 |
Cost of removal obligations [Member] | ||
Regulatory Liabilities [Line Items] | ||
Regulatory liabilities | 380 | 366 |
Derivatives [Member] | ||
Regulatory Liabilities [Line Items] | ||
Regulatory liabilities | 49 | 65 |
Commodity cost recovery [Member] | ||
Regulatory Liabilities [Line Items] | ||
Regulatory liabilities | 61 | 48 |
Other [Member] | ||
Regulatory Liabilities [Line Items] | ||
Regulatory liabilities | 83 | 85 |
IPL [Member] | ||
Regulatory Liabilities [Line Items] | ||
Regulatory liabilities | 648 | 644 |
IPL [Member] | Tax-related [Member] | ||
Regulatory Liabilities [Line Items] | ||
Regulatory liabilities | 297 | 299 |
IPL [Member] | Cost of removal obligations [Member] | ||
Regulatory Liabilities [Line Items] | ||
Regulatory liabilities | 241 | 242 |
IPL [Member] | Derivatives [Member] | ||
Regulatory Liabilities [Line Items] | ||
Regulatory liabilities | 28 | 34 |
IPL [Member] | Commodity cost recovery [Member] | ||
Regulatory Liabilities [Line Items] | ||
Regulatory liabilities | 25 | 13 |
IPL [Member] | Other [Member] | ||
Regulatory Liabilities [Line Items] | ||
Regulatory liabilities | 57 | 56 |
WPL [Member] | ||
Regulatory Liabilities [Line Items] | ||
Regulatory liabilities | 488 | 486 |
WPL [Member] | Tax-related [Member] | ||
Regulatory Liabilities [Line Items] | ||
Regulatory liabilities | 266 | 267 |
WPL [Member] | Cost of removal obligations [Member] | ||
Regulatory Liabilities [Line Items] | ||
Regulatory liabilities | 139 | 124 |
WPL [Member] | Derivatives [Member] | ||
Regulatory Liabilities [Line Items] | ||
Regulatory liabilities | 21 | 31 |
WPL [Member] | Commodity cost recovery [Member] | ||
Regulatory Liabilities [Line Items] | ||
Regulatory liabilities | 36 | 35 |
WPL [Member] | Other [Member] | ||
Regulatory Liabilities [Line Items] | ||
Regulatory liabilities | $ 26 | $ 29 |
Property, Plant and Equipment (
Property, Plant and Equipment (Narrative) (Details) - WPL [Member] $ in Millions | Mar. 31, 2024 USD ($) MW |
Property, Plant and Equipment [Line Items] | |
Electric Capacity of Solar Project | MW | 1,100 |
Construction Project Cost Target Exceedance | $ | $ 180 |
Receivables (Narrative) (Detail
Receivables (Narrative) (Details) - Receivables Sold [Member] - IPL [Member] - USD ($) $ in Millions | Apr. 30, 2024 | Mar. 31, 2024 |
Receivables [Line Items] | ||
Available capacity | $ 92 | |
Subsequent Event [Member] | ||
Receivables [Line Items] | ||
Available capacity | $ 80 | |
Financial Asset, Past Due [Member] | ||
Receivables [Line Items] | ||
Outstanding receivables past due | $ 22 |
Receivables (Maximum And Averag
Receivables (Maximum And Average Outstanding Cash Proceeds) (Details) - IPL [Member] - USD ($) $ in Millions | 3 Months Ended | |
Mar. 31, 2024 | Mar. 31, 2023 | |
Maximum [Member] | ||
Receivables [Line Items] | ||
Maximum outstanding aggregate cash proceeds (based on daily outstanding balances) | $ 79 | $ 89 |
Average [Member] | ||
Receivables [Line Items] | ||
Average outstanding aggregate cash proceeds (based on daily outstanding balances) | $ 24 | $ 58 |
Receivables (Receivables Sold U
Receivables (Receivables Sold Under The Agreement) (Details) - USD ($) $ in Millions | Mar. 31, 2024 | Dec. 31, 2023 |
Receivables [Line Items] | ||
Fair value of deferred proceeds | $ 184 | $ 216 |
IPL [Member] | ||
Receivables [Line Items] | ||
Fair value of deferred proceeds | 184 | 216 |
Receivables Sold [Member] | IPL [Member] | ||
Receivables [Line Items] | ||
Customer accounts receivable | 125 | 130 |
Unbilled utility revenues | 89 | 98 |
Other receivables | 1 | 1 |
Receivables sold to third party | 215 | 229 |
Less: cash proceeds | 18 | 1 |
Deferred proceeds | 197 | 228 |
Less: allowance for expected credit losses | 13 | 12 |
Fair value of deferred proceeds | $ 184 | $ 216 |
Receivables (Additional Attribu
Receivables (Additional Attributes Of Receivables Sold Under The Agreement) (Details) - IPL [Member] - USD ($) $ in Millions | 3 Months Ended | |
Mar. 31, 2024 | Mar. 31, 2023 | |
Receivables [Line Items] | ||
Collections | $ 557 | $ 591 |
Write-offs, net of recoveries | $ 3 | $ 2 |
Investments (Unconsolidated Equ
Investments (Unconsolidated Equity Investments) (Details) - USD ($) $ in Millions | 3 Months Ended | |
Mar. 31, 2024 | Mar. 31, 2023 | |
Schedule of Equity Method Investments [Line Items] | ||
Equity (income) loss from unconsolidated investments, net | $ (15) | $ (17) |
ATC Holdings [Member] | ||
Schedule of Equity Method Investments [Line Items] | ||
Equity (income) loss from unconsolidated investments, net | (12) | (13) |
Other [Member] | ||
Schedule of Equity Method Investments [Line Items] | ||
Equity (income) loss from unconsolidated investments, net | (3) | (4) |
Total [Member] | ||
Schedule of Equity Method Investments [Line Items] | ||
Equity (income) loss from unconsolidated investments, net | $ (15) | $ (17) |
Common Equity (Common Share Act
Common Equity (Common Share Activity) (Details) | 3 Months Ended |
Mar. 31, 2024 shares | |
Common Stock Oustanding [Roll Forward] | |
Shares outstanding, January 1, 2024 (in shares) | 256,096,848 |
Shareowner Direct Plan (in shares) | 127,917 |
Equity-based compensation plans (in shares) | 154,267 |
Shares outstanding, March 31, 2024 (in shares) | 256,379,032 |
Common Equity (Changes in Share
Common Equity (Changes in Shareowners' Equity) (Details) - USD ($) $ / shares in Units, $ in Millions | 3 Months Ended | |
Mar. 31, 2024 | Mar. 31, 2023 | |
Changes in Shareowners' Equity Roll Forward [Line Items] | ||
Beginning balance | $ 6,777 | |
Beginning balance | 6,777 | $ 6,276 |
Net income attributable to common shareowners | 158 | 163 |
Net income | 158 | 163 |
Common stock dividends | (123) | (113) |
Shareowner Direct Plan issuances | 6 | 6 |
Equity-based compensation plans and other | (2) | (3) |
Other comprehensive income (loss), net of tax | 1 | (1) |
Ending balance | 6,817 | |
Ending balance | $ 6,817 | $ 6,328 |
Common stock dividends (in dollars per share) | $ 0.48 | $ 0.4525 |
Common Stock [Member] | ||
Changes in Shareowners' Equity Roll Forward [Line Items] | ||
Beginning balance | $ 3 | $ 3 |
Ending balance | 3 | 3 |
Additional Paid-in Capital [Member] | ||
Changes in Shareowners' Equity Roll Forward [Line Items] | ||
Beginning balance | 3,030 | 2,777 |
Shareowner Direct Plan issuances | 6 | 6 |
Equity-based compensation plans and other | (3) | (3) |
Ending balance | 3,033 | 2,780 |
Retained Earnings [Member] | ||
Changes in Shareowners' Equity Roll Forward [Line Items] | ||
Beginning balance | 3,756 | 3,509 |
Net income attributable to common shareowners | 158 | 163 |
Common stock dividends | (123) | (113) |
Ending balance | 3,791 | 3,559 |
Accumulated Other Comprehensive Income (Loss) [Member] | ||
Changes in Shareowners' Equity Roll Forward [Line Items] | ||
Beginning balance | 1 | 0 |
Other comprehensive income (loss), net of tax | 1 | (1) |
Ending balance | 2 | (1) |
Shares in Deferred Compensation Trust [Member] | ||
Changes in Shareowners' Equity Roll Forward [Line Items] | ||
Beginning balance | (13) | (13) |
Equity-based compensation plans and other | 1 | |
Ending balance | (12) | (13) |
IPL [Member] | ||
Changes in Shareowners' Equity Roll Forward [Line Items] | ||
Beginning balance | 3,974 | |
Beginning balance | 3,974 | 3,808 |
Net income | 63 | 72 |
Common stock dividends | (50) | (70) |
Capital contributions from parent | 50 | 0 |
Ending balance | 4,037 | |
Ending balance | 4,037 | 3,810 |
IPL [Member] | Common Stock [Member] | ||
Changes in Shareowners' Equity Roll Forward [Line Items] | ||
Beginning balance | 33 | 33 |
Ending balance | 33 | 33 |
IPL [Member] | Additional Paid-in Capital [Member] | ||
Changes in Shareowners' Equity Roll Forward [Line Items] | ||
Beginning balance | 2,887 | 2,807 |
Capital contributions from parent | 50 | |
Ending balance | 2,937 | 2,807 |
IPL [Member] | Retained Earnings [Member] | ||
Changes in Shareowners' Equity Roll Forward [Line Items] | ||
Beginning balance | 1,054 | 968 |
Net income | 63 | 72 |
Common stock dividends | (50) | (70) |
Ending balance | 1,067 | 970 |
WPL [Member] | ||
Changes in Shareowners' Equity Roll Forward [Line Items] | ||
Beginning balance | 3,897 | |
Beginning balance | 3,897 | 3,491 |
Net income | 92 | 88 |
Common stock dividends | (49) | (46) |
Capital contributions from parent | 55 | 180 |
Ending balance | 3,995 | |
Ending balance | 3,995 | 3,713 |
WPL [Member] | Common Stock [Member] | ||
Changes in Shareowners' Equity Roll Forward [Line Items] | ||
Beginning balance | 66 | 66 |
Ending balance | 66 | 66 |
WPL [Member] | Additional Paid-in Capital [Member] | ||
Changes in Shareowners' Equity Roll Forward [Line Items] | ||
Beginning balance | 2,478 | 2,233 |
Capital contributions from parent | 55 | 180 |
Ending balance | 2,533 | 2,413 |
WPL [Member] | Retained Earnings [Member] | ||
Changes in Shareowners' Equity Roll Forward [Line Items] | ||
Beginning balance | 1,353 | 1,192 |
Net income | 92 | 88 |
Common stock dividends | (49) | (46) |
Ending balance | $ 1,396 | $ 1,234 |
Debt (Narrative) (Details)
Debt (Narrative) (Details) - USD ($) $ in Millions | 3 Months Ended | |||
Mar. 31, 2024 | Mar. 31, 2023 | Mar. 31, 2025 | Dec. 31, 2023 | |
Debt [Line Items] | ||||
Line of credit facility, current borrowing capacity | $ 1,000 | |||
Payments to retire long-term debt | 300 | $ 0 | ||
Long-term debt, fair value | 9,051 | $ 8,677 | ||
Parent Company [Member] | ||||
Debt [Line Items] | ||||
Line of credit facility, current borrowing capacity | 500 | |||
IPL [Member] | ||||
Debt [Line Items] | ||||
Line of credit facility, current borrowing capacity | 200 | |||
Long-term debt, fair value | 3,607 | 3,664 | ||
WPL [Member] | ||||
Debt [Line Items] | ||||
Line of credit facility, current borrowing capacity | 300 | |||
Long-term debt, fair value | 3,176 | $ 2,933 | ||
Term Loan Credit Agreement [Member] | Term loan credit agreement through March 2025 [Member] | Alliant Energy Finance LLC [Member] | ||||
Debt [Line Items] | ||||
Long-term debt | $ 300 | |||
Interest rate, percent | 6% | |||
Term Loan Credit Agreement [Member] | Term loan credit agreement through March 2025 [Member] | Alliant Energy Finance LLC [Member] | Forecast [Member] | ||||
Debt [Line Items] | ||||
Long-term debt | $ 100 | |||
Term Loan Credit Agreement [Member] | Term loan credit agreement through March 2024 [Member] | Alliant Energy Finance LLC [Member] | ||||
Debt [Line Items] | ||||
Payments to retire long-term debt | $ 300 | |||
Debentures [Member] | 5.375% debenture, due 2034 [Member] | WPL [Member] | ||||
Debt [Line Items] | ||||
Long-term debt | $ 300 | |||
Interest rate, percent | 5.375% | |||
Convertible Senior Notes [Member] | 3.875% convertible senior notes, due 2026 [Member] | ||||
Debt [Line Items] | ||||
Long-term debt, carrying value | $ 569 | |||
Unamortized debt issuance costs | 6 | |||
Long-term debt, fair value | $ 567 | |||
Shares included in diluted earnings per share (in shares) | 0 |
Debt (Credit Facilities) (Detai
Debt (Credit Facilities) (Details) $ in Millions | Mar. 31, 2024 USD ($) |
Debt [Line Items] | |
Amount outstanding | $ 334 |
Weighted average interest rates | 5.50% |
Available credit facility capacity | $ 666 |
IPL [Member] | |
Debt [Line Items] | |
Amount outstanding | $ 0 |
Weighted average interest rates | 0% |
Available credit facility capacity | $ 200 |
WPL [Member] | |
Debt [Line Items] | |
Amount outstanding | $ 0 |
Weighted average interest rates | 0% |
Available credit facility capacity | $ 300 |
Debt (Other Short-Term Borrowin
Debt (Other Short-Term Borrowings) (Details) - USD ($) $ in Millions | 3 Months Ended | |
Mar. 31, 2024 | Mar. 31, 2023 | |
Debt [Line Items] | ||
Maximum amount outstanding (based on daily outstanding balances) | $ 632 | $ 793 |
Average amount outstanding (based on daily outstanding balances) | $ 487 | $ 574 |
Weighted average interest rates | 5.50% | 4.80% |
IPL [Member] | ||
Debt [Line Items] | ||
Maximum amount outstanding (based on daily outstanding balances) | $ 14 | $ 0 |
Average amount outstanding (based on daily outstanding balances) | $ 1 | $ 0 |
Weighted average interest rates | 5.50% | 0% |
WPL [Member] | ||
Debt [Line Items] | ||
Maximum amount outstanding (based on daily outstanding balances) | $ 390 | $ 349 |
Average amount outstanding (based on daily outstanding balances) | $ 255 | $ 304 |
Weighted average interest rates | 5.50% | 4.80% |
Revenue (Disaggregation of Reve
Revenue (Disaggregation of Revenues) (Details) - USD ($) $ in Millions | 3 Months Ended | |
Mar. 31, 2024 | Mar. 31, 2023 | |
Disaggregation of Revenue [Line Items] | ||
Revenue from contracts with customers | $ 1,031 | $ 1,077 |
Electric [Member] | ||
Disaggregation of Revenue [Line Items] | ||
Revenue from contracts with customers | 791 | 768 |
Electric [Member] | Retail - residential [Member] | ||
Disaggregation of Revenue [Line Items] | ||
Revenue from contracts with customers | 297 | 285 |
Electric [Member] | Retail - commercial [Member] | ||
Disaggregation of Revenue [Line Items] | ||
Revenue from contracts with customers | 186 | 185 |
Electric [Member] | Retail - industrial [Member] | ||
Disaggregation of Revenue [Line Items] | ||
Revenue from contracts with customers | 223 | 216 |
Electric [Member] | Wholesale [Member] | ||
Disaggregation of Revenue [Line Items] | ||
Revenue from contracts with customers | 47 | 46 |
Electric [Member] | Other [Member] | ||
Disaggregation of Revenue [Line Items] | ||
Revenue from contracts with customers | 38 | 36 |
Gas [Member] | ||
Disaggregation of Revenue [Line Items] | ||
Revenue from contracts with customers | 205 | 276 |
Gas [Member] | Retail - residential [Member] | ||
Disaggregation of Revenue [Line Items] | ||
Revenue from contracts with customers | 126 | 167 |
Gas [Member] | Retail - commercial [Member] | ||
Disaggregation of Revenue [Line Items] | ||
Revenue from contracts with customers | 61 | 88 |
Gas [Member] | Retail - industrial [Member] | ||
Disaggregation of Revenue [Line Items] | ||
Revenue from contracts with customers | 5 | 7 |
Gas [Member] | Other [Member] | ||
Disaggregation of Revenue [Line Items] | ||
Revenue from contracts with customers | 13 | 14 |
Other Utility [Member] | ||
Disaggregation of Revenue [Line Items] | ||
Revenue from contracts with customers | 13 | 11 |
Other Utility [Member] | Steam [Member] | ||
Disaggregation of Revenue [Line Items] | ||
Revenue from contracts with customers | 12 | 10 |
Other Utility [Member] | Other [Member] | ||
Disaggregation of Revenue [Line Items] | ||
Revenue from contracts with customers | 1 | 1 |
Non-utility and Other [Member] | ||
Disaggregation of Revenue [Line Items] | ||
Revenue from contracts with customers | 22 | 22 |
Non-utility and Other [Member] | Other [Member] | ||
Disaggregation of Revenue [Line Items] | ||
Revenue from contracts with customers | 22 | 22 |
IPL [Member] | ||
Disaggregation of Revenue [Line Items] | ||
Revenue from contracts with customers | 513 | 549 |
IPL [Member] | Electric [Member] | ||
Disaggregation of Revenue [Line Items] | ||
Revenue from contracts with customers | 392 | 388 |
IPL [Member] | Electric [Member] | Retail - residential [Member] | ||
Disaggregation of Revenue [Line Items] | ||
Revenue from contracts with customers | 150 | 143 |
IPL [Member] | Electric [Member] | Retail - commercial [Member] | ||
Disaggregation of Revenue [Line Items] | ||
Revenue from contracts with customers | 114 | 112 |
IPL [Member] | Electric [Member] | Retail - industrial [Member] | ||
Disaggregation of Revenue [Line Items] | ||
Revenue from contracts with customers | 112 | 107 |
IPL [Member] | Electric [Member] | Wholesale [Member] | ||
Disaggregation of Revenue [Line Items] | ||
Revenue from contracts with customers | 13 | 12 |
IPL [Member] | Electric [Member] | Other [Member] | ||
Disaggregation of Revenue [Line Items] | ||
Revenue from contracts with customers | 3 | 14 |
IPL [Member] | Gas [Member] | ||
Disaggregation of Revenue [Line Items] | ||
Revenue from contracts with customers | 108 | 150 |
IPL [Member] | Gas [Member] | Retail - residential [Member] | ||
Disaggregation of Revenue [Line Items] | ||
Revenue from contracts with customers | 68 | 93 |
IPL [Member] | Gas [Member] | Retail - commercial [Member] | ||
Disaggregation of Revenue [Line Items] | ||
Revenue from contracts with customers | 30 | 44 |
IPL [Member] | Gas [Member] | Retail - industrial [Member] | ||
Disaggregation of Revenue [Line Items] | ||
Revenue from contracts with customers | 3 | 4 |
IPL [Member] | Gas [Member] | Other [Member] | ||
Disaggregation of Revenue [Line Items] | ||
Revenue from contracts with customers | 7 | 9 |
IPL [Member] | Other Utility [Member] | ||
Disaggregation of Revenue [Line Items] | ||
Revenue from contracts with customers | 13 | 11 |
IPL [Member] | Other Utility [Member] | Steam [Member] | ||
Disaggregation of Revenue [Line Items] | ||
Revenue from contracts with customers | 12 | 10 |
IPL [Member] | Other Utility [Member] | Other [Member] | ||
Disaggregation of Revenue [Line Items] | ||
Revenue from contracts with customers | 1 | 1 |
WPL [Member] | ||
Disaggregation of Revenue [Line Items] | ||
Revenue from contracts with customers | 496 | 506 |
WPL [Member] | Electric [Member] | ||
Disaggregation of Revenue [Line Items] | ||
Revenue from contracts with customers | 399 | 380 |
WPL [Member] | Electric [Member] | Retail - residential [Member] | ||
Disaggregation of Revenue [Line Items] | ||
Revenue from contracts with customers | 147 | 142 |
WPL [Member] | Electric [Member] | Retail - commercial [Member] | ||
Disaggregation of Revenue [Line Items] | ||
Revenue from contracts with customers | 72 | 73 |
WPL [Member] | Electric [Member] | Retail - industrial [Member] | ||
Disaggregation of Revenue [Line Items] | ||
Revenue from contracts with customers | 111 | 109 |
WPL [Member] | Electric [Member] | Wholesale [Member] | ||
Disaggregation of Revenue [Line Items] | ||
Revenue from contracts with customers | 34 | 34 |
WPL [Member] | Electric [Member] | Other [Member] | ||
Disaggregation of Revenue [Line Items] | ||
Revenue from contracts with customers | 35 | 22 |
WPL [Member] | Gas [Member] | ||
Disaggregation of Revenue [Line Items] | ||
Revenue from contracts with customers | 97 | 126 |
WPL [Member] | Gas [Member] | Retail - residential [Member] | ||
Disaggregation of Revenue [Line Items] | ||
Revenue from contracts with customers | 58 | 74 |
WPL [Member] | Gas [Member] | Retail - commercial [Member] | ||
Disaggregation of Revenue [Line Items] | ||
Revenue from contracts with customers | 31 | 44 |
WPL [Member] | Gas [Member] | Retail - industrial [Member] | ||
Disaggregation of Revenue [Line Items] | ||
Revenue from contracts with customers | 2 | 3 |
WPL [Member] | Gas [Member] | Other [Member] | ||
Disaggregation of Revenue [Line Items] | ||
Revenue from contracts with customers | 6 | 5 |
WPL [Member] | Other Utility [Member] | ||
Disaggregation of Revenue [Line Items] | ||
Revenue from contracts with customers | 0 | 0 |
WPL [Member] | Other Utility [Member] | Other [Member] | ||
Disaggregation of Revenue [Line Items] | ||
Revenue from contracts with customers | $ 0 | $ 0 |
Income Taxes (Schedule Of Effec
Income Taxes (Schedule Of Effective Income Tax Rates) (Details) | 3 Months Ended | |
Mar. 31, 2024 | Mar. 31, 2023 | |
Effective Tax Rate [Line Items] | ||
Overall income tax rate | (7.00%) | (1.00%) |
IPL [Member] | ||
Effective Tax Rate [Line Items] | ||
Overall income tax rate | (19.00%) | (18.00%) |
WPL [Member] | ||
Effective Tax Rate [Line Items] | ||
Overall income tax rate | 6% | 12% |
Income Taxes (Summary Of Tax Cr
Income Taxes (Summary Of Tax Credit Carryforwards) (Details) $ in Millions | Mar. 31, 2024 USD ($) |
State [Member] | |
Carryforwards [Line Items] | |
Net operating losses, carryforward amount | $ 403 |
Federal [Member] | |
Carryforwards [Line Items] | |
Tax credits, carryforward amount | 685 |
IPL [Member] | State [Member] | |
Carryforwards [Line Items] | |
Net operating losses, carryforward amount | 6 |
IPL [Member] | Federal [Member] | |
Carryforwards [Line Items] | |
Tax credits, carryforward amount | 462 |
WPL [Member] | State [Member] | |
Carryforwards [Line Items] | |
Net operating losses, carryforward amount | 1 |
WPL [Member] | Federal [Member] | |
Carryforwards [Line Items] | |
Tax credits, carryforward amount | $ 214 |
Benefit Plans (Narrative) (Deta
Benefit Plans (Narrative) (Details) $ in Millions | 3 Months Ended |
Mar. 31, 2024 USD ($) shares | |
Defined Benefit Plan Disclosure [Line Items] | |
Unrecognized compensation cost | $ 22 |
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 | $ 11 |
WPL [Member] | |
Defined Benefit Plan Disclosure [Line Items] | |
Unrecognized compensation cost | $ 10 |
Omnibus Incentive Plan [Member] | |
Defined Benefit Plan Disclosure [Line Items] | |
Shares included in diluted earnings per share (in shares) | shares | 242,680 |
Benefit Plans (Defined Benefit
Benefit Plans (Defined Benefit Pension And Other Postretirement Benefits Plans) (Details) - USD ($) $ in Millions | 3 Months Ended | |
Mar. 31, 2024 | Mar. 31, 2023 | |
Defined benefit pension plans [Member] | ||
Defined Benefit Plan Disclosure [Line Items] | ||
Service cost | $ 1 | $ 1 |
Interest cost | 11 | 11 |
Expected return on plan assets | (13) | (13) |
Amortization of actuarial loss | 6 | 7 |
Total | 5 | 6 |
OPEB Plans [Member] | ||
Defined Benefit Plan Disclosure [Line Items] | ||
Service cost | 0 | 1 |
Interest cost | 2 | 2 |
Expected return on plan assets | (1) | (1) |
Amortization of actuarial loss | 0 | 0 |
Total | 1 | 2 |
IPL [Member] | Defined benefit pension plans [Member] | ||
Defined Benefit Plan Disclosure [Line Items] | ||
Service cost | 1 | 1 |
Interest cost | 5 | 5 |
Expected return on plan assets | (7) | (7) |
Amortization of actuarial loss | 2 | 3 |
Total | 1 | 2 |
IPL [Member] | OPEB Plans [Member] | ||
Defined Benefit Plan Disclosure [Line Items] | ||
Service cost | 0 | 0 |
Interest cost | 1 | 1 |
Expected return on plan assets | (1) | (1) |
Amortization of actuarial loss | 0 | 0 |
Total | 0 | 0 |
WPL [Member] | Defined benefit pension plans [Member] | ||
Defined Benefit Plan Disclosure [Line Items] | ||
Interest cost | 5 | 5 |
Expected return on plan assets | (6) | (5) |
Amortization of actuarial loss | 3 | 3 |
Total | 2 | 3 |
WPL [Member] | OPEB Plans [Member] | ||
Defined Benefit Plan Disclosure [Line Items] | ||
Interest cost | 1 | 1 |
Expected return on plan assets | 0 | 0 |
Amortization of actuarial loss | 0 | 0 |
Total | $ 1 | $ 1 |
Benefit Plans (Recognized Compe
Benefit Plans (Recognized Compensation Expense And Income Tax Benefits) (Details) - USD ($) $ in Millions | 3 Months Ended | |
Mar. 31, 2024 | Mar. 31, 2023 | |
Compensation expense | $ 4 | $ 3 |
Income tax benefits | 1 | 1 |
IPL [Member] | ||
Compensation expense | 2 | 2 |
Income tax benefits | 1 | 0 |
WPL [Member] | ||
Compensation expense | 2 | 1 |
Income tax benefits | $ 0 | $ 0 |
Benefit Plans (Summary Of Equit
Benefit Plans (Summary Of Equity-based Compensation Plans Grants) (Details) | 3 Months Ended |
Mar. 31, 2024 $ / shares shares | |
Performance Shares (total shareowner return metric) [Member] | |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | |
Grants (in shares/units) | shares | 123,098 |
Weighted average grant date fair value (in dollars per share/unit) | $ / shares | $ 46.04 |
Performance Shares (net income and diversity metric) [Member] | |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | |
Grants (in shares/units) | shares | 140,683 |
Weighted average grant date fair value (in dollars per share/unit) | $ / shares | $ 48.40 |
Restricted Stock Units [Member] | |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | |
Grants (in shares/units) | shares | 120,557 |
Weighted average grant date fair value (in dollars per share/unit) | $ / shares | $ 48.40 |
Derivative Instruments (Narrati
Derivative Instruments (Narrative) (Details) - USD ($) $ in Millions | 3 Months Ended | ||
Mar. 31, 2024 | Mar. 31, 2023 | Dec. 31, 2023 | |
Derivative Instruments [Line Items] | |||
Non-current interest rate derivative assets | $ 173 | $ 177 | |
Accumulated other comprehensive income, interest rate swap | 2 | $ 1 | |
Interest expense, interest rate swap | 107 | $ 94 | |
Alliant Energy Finance LLC [Member] | Interest Rate Swap [Member] | Term Loan Credit Agreement [Member] | |||
Derivative Instruments [Line Items] | |||
Non-current interest rate derivative assets | 3 | ||
Accumulated other comprehensive income, interest rate swap | 2 | ||
Interest expense, interest rate swap | $ 1 | $ 1 |
Derivative Instruments (Notiona
Derivative Instruments (Notional Amounts Of Derivative Instruments) (Details) - Commodity [Member] | 3 Months Ended |
Mar. 31, 2024 Dekatherms MWh | |
Electricity (MWhs) [Member] | |
Notional Amount of Derivatives [Line Items] | |
Notional unit amount of derivatives (in MWhs) | 1,412 |
Electricity (MWhs) [Member] | IPL [Member] | |
Notional Amount of Derivatives [Line Items] | |
Notional unit amount of derivatives (in MWhs) | 673 |
Electricity (MWhs) [Member] | WPL [Member] | |
Notional Amount of Derivatives [Line Items] | |
Notional unit amount of derivatives (in MWhs) | 739 |
FTRs (MWhs) [Member] | |
Notional Amount of Derivatives [Line Items] | |
Notional unit amount of derivatives (in MWhs) | 4,162 |
FTRs (MWhs) [Member] | IPL [Member] | |
Notional Amount of Derivatives [Line Items] | |
Notional unit amount of derivatives (in MWhs) | 1,444 |
FTRs (MWhs) [Member] | WPL [Member] | |
Notional Amount of Derivatives [Line Items] | |
Notional unit amount of derivatives (in MWhs) | 2,718 |
Natural Gas (Dths) [Member] | |
Notional Amount of Derivatives [Line Items] | |
Notional unit amount of derivatives (in Dths) | Dekatherms | 173,746 |
Natural Gas (Dths) [Member] | IPL [Member] | |
Notional Amount of Derivatives [Line Items] | |
Notional unit amount of derivatives (in Dths) | Dekatherms | 78,790 |
Natural Gas (Dths) [Member] | WPL [Member] | |
Notional Amount of Derivatives [Line Items] | |
Notional unit amount of derivatives (in Dths) | Dekatherms | 94,956 |
Derivative Instruments (Fair Va
Derivative Instruments (Fair Value Of Financial Instruments) (Details) - Commodity Contracts [Member] - USD ($) $ in Millions | Mar. 31, 2024 | Dec. 31, 2023 |
Derivatives, Fair Value [Line Items] | ||
Current derivative assets | $ 16 | $ 44 |
Non-current derivative assets | 40 | 44 |
Current derivative liabilities | 49 | 51 |
Non-current derivative liabilities | 45 | 47 |
IPL [Member] | ||
Derivatives, Fair Value [Line Items] | ||
Current derivative assets | 12 | 30 |
Non-current derivative assets | 22 | 24 |
Current derivative liabilities | 23 | 22 |
Non-current derivative liabilities | 7 | 8 |
WPL [Member] | ||
Derivatives, Fair Value [Line Items] | ||
Current derivative assets | 4 | 14 |
Non-current derivative assets | 18 | 20 |
Current derivative liabilities | 26 | 29 |
Non-current derivative liabilities | $ 38 | $ 39 |
Derivative Instruments (Balance
Derivative Instruments (Balance Sheet Offsetting) (Details) - Commodity Contracts [Member] - USD ($) $ in Millions | Mar. 31, 2024 | Dec. 31, 2023 |
Derivative Instruments [Line Items] | ||
Derivative assets, Gross (as reported) | $ 56 | $ 88 |
Derivative assets, Net | 26 | 47 |
Derivative liabilities, Gross (as reported) | 94 | 98 |
Derivative liabilities, Net | 64 | 57 |
IPL [Member] | ||
Derivative Instruments [Line Items] | ||
Derivative assets, Gross (as reported) | 34 | 54 |
Derivative assets, Net | 17 | 32 |
Derivative liabilities, Gross (as reported) | 30 | 30 |
Derivative liabilities, Net | 13 | 8 |
WPL [Member] | ||
Derivative Instruments [Line Items] | ||
Derivative assets, Gross (as reported) | 22 | 34 |
Derivative assets, Net | 9 | 15 |
Derivative liabilities, Gross (as reported) | 64 | 68 |
Derivative liabilities, Net | $ 51 | $ 49 |
Fair Value Measurements (Fair V
Fair Value Measurements (Fair Value Measurements) (Details) - USD ($) $ in Millions | Mar. 31, 2024 | Dec. 31, 2023 |
Carrying Amount [Member] | ||
Assets: | ||
Money market fund investments | $ 10 | $ 45 |
Deferred proceeds | 184 | 216 |
Liabilities: | ||
Long-term debt (incl. current maturities) | 9,333 | 9,034 |
Carrying Amount [Member] | IPL [Member] | ||
Assets: | ||
Money market fund investments | 6 | 45 |
Deferred proceeds | 184 | 216 |
Liabilities: | ||
Long-term debt (incl. current maturities) | 3,945 | 3,945 |
Carrying Amount [Member] | WPL [Member] | ||
Liabilities: | ||
Long-term debt (incl. current maturities) | 3,367 | 3,070 |
Carrying Amount [Member] | Commodity Contracts [Member] | ||
Assets: | ||
Derivatives | 56 | 88 |
Liabilities: | ||
Derivatives | 94 | 98 |
Carrying Amount [Member] | Commodity Contracts [Member] | IPL [Member] | ||
Assets: | ||
Derivatives | 34 | 54 |
Liabilities: | ||
Derivatives | 30 | 30 |
Carrying Amount [Member] | Commodity Contracts [Member] | WPL [Member] | ||
Assets: | ||
Derivatives | 22 | 34 |
Liabilities: | ||
Derivatives | 64 | 68 |
Carrying Amount [Member] | Interest Rate Swap [Member] | ||
Assets: | ||
Derivatives | 3 | 1 |
Money market fund investments | 10 | 45 |
Deferred proceeds | 184 | 216 |
Liabilities: | ||
Long-term debt (incl. current maturities) | 9,051 | 8,677 |
IPL [Member] | ||
Assets: | ||
Money market fund investments | 6 | 45 |
Deferred proceeds | 184 | 216 |
Liabilities: | ||
Long-term debt (incl. current maturities) | 3,607 | 3,664 |
WPL [Member] | ||
Liabilities: | ||
Long-term debt (incl. current maturities) | 3,176 | 2,933 |
Commodity Contracts [Member] | ||
Assets: | ||
Derivatives | 56 | 88 |
Liabilities: | ||
Derivatives | 94 | 98 |
Commodity Contracts [Member] | IPL [Member] | ||
Assets: | ||
Derivatives | 34 | 54 |
Liabilities: | ||
Derivatives | 30 | 30 |
Commodity Contracts [Member] | WPL [Member] | ||
Assets: | ||
Derivatives | 22 | 34 |
Liabilities: | ||
Derivatives | 64 | 68 |
Interest Rate Swap [Member] | ||
Assets: | ||
Derivatives | 3 | 1 |
Level 1 [Member] | ||
Assets: | ||
Money market fund investments | 10 | 45 |
Deferred proceeds | 0 | 0 |
Liabilities: | ||
Long-term debt (incl. current maturities) | 0 | 0 |
Level 1 [Member] | IPL [Member] | ||
Assets: | ||
Money market fund investments | 6 | 45 |
Deferred proceeds | 0 | 0 |
Liabilities: | ||
Long-term debt (incl. current maturities) | 0 | 0 |
Level 1 [Member] | WPL [Member] | ||
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 1 [Member] | Interest Rate Swap [Member] | ||
Assets: | ||
Derivatives | 0 | 0 |
Level 2 [Member] | ||
Assets: | ||
Money market fund investments | 0 | 0 |
Deferred proceeds | 0 | 0 |
Liabilities: | ||
Long-term debt (incl. current maturities) | 9,051 | 8,677 |
Level 2 [Member] | IPL [Member] | ||
Assets: | ||
Money market fund investments | 0 | 0 |
Deferred proceeds | 0 | 0 |
Liabilities: | ||
Long-term debt (incl. current maturities) | 3,607 | 3,664 |
Level 2 [Member] | WPL [Member] | ||
Liabilities: | ||
Long-term debt (incl. current maturities) | 3,176 | 2,933 |
Level 2 [Member] | Commodity Contracts [Member] | ||
Assets: | ||
Derivatives | 46 | 59 |
Liabilities: | ||
Derivatives | 91 | 93 |
Level 2 [Member] | Commodity Contracts [Member] | IPL [Member] | ||
Assets: | ||
Derivatives | 26 | 30 |
Liabilities: | ||
Derivatives | 27 | 25 |
Level 2 [Member] | Commodity Contracts [Member] | WPL [Member] | ||
Assets: | ||
Derivatives | 20 | 29 |
Liabilities: | ||
Derivatives | 64 | 68 |
Level 2 [Member] | Interest Rate Swap [Member] | ||
Assets: | ||
Derivatives | 3 | 1 |
Level 3 [Member] | ||
Assets: | ||
Money market fund investments | 0 | 0 |
Deferred proceeds | 184 | 216 |
Liabilities: | ||
Long-term debt (incl. current maturities) | 0 | 0 |
Level 3 [Member] | IPL [Member] | ||
Assets: | ||
Money market fund investments | 0 | 0 |
Deferred proceeds | 184 | 216 |
Liabilities: | ||
Long-term debt (incl. current maturities) | 0 | 0 |
Level 3 [Member] | WPL [Member] | ||
Liabilities: | ||
Long-term debt (incl. current maturities) | 0 | 0 |
Level 3 [Member] | Commodity Contracts [Member] | ||
Assets: | ||
Derivatives | 10 | 29 |
Liabilities: | ||
Derivatives | 3 | 5 |
Level 3 [Member] | Commodity Contracts [Member] | IPL [Member] | ||
Assets: | ||
Derivatives | 8 | 24 |
Liabilities: | ||
Derivatives | 3 | 5 |
Level 3 [Member] | Commodity Contracts [Member] | WPL [Member] | ||
Assets: | ||
Derivatives | 2 | 5 |
Liabilities: | ||
Derivatives | 0 | 0 |
Level 3 [Member] | Interest Rate Swap [Member] | ||
Assets: | ||
Derivatives | $ 0 | $ 0 |
Fair Value Measurements (Fair_2
Fair Value Measurements (Fair Value Measurements Using Significant Unobservable Inputs) (Details) - USD ($) $ in Millions | 3 Months Ended | |
Mar. 31, 2024 | Mar. 31, 2023 | |
Commodity Contracts [Member] | ||
Fair Value, Assets and Liabilities, Net, Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] | ||
Beginning balance | $ 24 | $ 19 |
Total net gains (losses) included in changes in net assets (realized/unrealized) | (3) | (4) |
Settlements | (14) | (20) |
Ending balance | 7 | (5) |
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 March 31 | (3) | (4) |
Commodity Contracts [Member] | IPL [Member] | ||
Fair Value, Assets and Liabilities, Net, Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] | ||
Beginning balance | 19 | 16 |
Total net gains (losses) included in changes in net assets (realized/unrealized) | (4) | 1 |
Settlements | (10) | (17) |
Ending balance | 5 | 0 |
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 March 31 | (4) | 1 |
Commodity Contracts [Member] | WPL [Member] | ||
Fair Value, Assets and Liabilities, Net, Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] | ||
Beginning balance | 5 | 3 |
Total net gains (losses) included in changes in net assets (realized/unrealized) | 1 | (5) |
Settlements | (4) | (3) |
Ending balance | 2 | (5) |
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 March 31 | 1 | (5) |
Deferred Proceeds [Member] | ||
Fair Value, Assets and Liabilities, Net, Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] | ||
Beginning balance | 216 | 185 |
Total net gains (losses) included in changes in net assets (realized/unrealized) | 0 | 0 |
Settlements | (32) | (32) |
Ending balance | 184 | 153 |
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 March 31 | 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 | 216 | 185 |
Total net gains (losses) included in changes in net assets (realized/unrealized) | 0 | 0 |
Settlements | (32) | (32) |
Ending balance | 184 | 153 |
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 March 31 | $ 0 | $ 0 |
Fair Value Measurements (Fair_3
Fair Value Measurements (Fair Value Of Net Derivative Assets (Liabilities)) (Details) - Commodity Contracts [Member] - USD ($) $ in Millions | Mar. 31, 2024 | Dec. 31, 2023 | Mar. 31, 2023 | Dec. 31, 2022 |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] | ||||
Fair value, net derivative assets | $ 7 | $ 24 | $ (5) | $ 19 |
Excluding Financial Transmission Rights [Member] | ||||
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] | ||||
Fair value, net derivative assets | 3 | |||
Fair value, net derivative liabilities | (1) | |||
Financial Transmission Rights [Member] | ||||
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] | ||||
Fair value, net derivative assets | 8 | 21 | ||
IPL [Member] | ||||
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] | ||||
Fair value, net derivative assets | 5 | 19 | 0 | 16 |
IPL [Member] | Excluding Financial Transmission Rights [Member] | ||||
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] | ||||
Fair value, net derivative assets | 3 | |||
Fair value, net derivative liabilities | (1) | |||
IPL [Member] | Financial Transmission Rights [Member] | ||||
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] | ||||
Fair value, net derivative assets | 6 | 16 | ||
WPL [Member] | ||||
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] | ||||
Fair value, net derivative assets | 2 | 5 | $ (5) | $ 3 |
WPL [Member] | Excluding Financial Transmission Rights [Member] | ||||
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] | ||||
Fair value, net derivative liabilities | 0 | 0 | ||
WPL [Member] | Financial Transmission Rights [Member] | ||||
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] | ||||
Fair value, net derivative assets | $ 2 | $ 5 |
Commitments And Contingencies_2
Commitments And Contingencies (Narrative) (Details) - USD ($) $ in Millions | 3 Months Ended | 12 Months Ended | |
Mar. 31, 2024 | Dec. 31, 2020 | Dec. 31, 2019 | |
Commitments and Contingencies [Line Items] | |||
Minimum future commitments | $ 1,098 | ||
IPL [Member] | |||
Commitments and Contingencies [Line Items] | |||
Minimum future commitments | 497 | ||
WPL [Member] | |||
Commitments and Contingencies [Line Items] | |||
Minimum future commitments | 554 | ||
Capital Purchase Commitment [Member] | |||
Commitments and Contingencies [Line Items] | |||
Minimum future commitments | 191 | ||
Capital Purchase Commitment [Member] | IPL [Member] | |||
Commitments and Contingencies [Line Items] | |||
Minimum future commitments | 80 | ||
Capital Purchase Commitment [Member] | WPL [Member] | |||
Commitments and Contingencies [Line Items] | |||
Minimum future commitments | 111 | ||
Indemnification Agreement [Member] | |||
Commitments and Contingencies [Line Items] | |||
Obligations, maximum | 51 | ||
Indemnification Agreement [Member] | Purchased Power [Member] | |||
Commitments and Contingencies [Line Items] | |||
Obligations, maximum | 17 | ||
Indemnification Agreement [Member] | Renewable Tax Credits Transferred [Member] | IPL [Member] | |||
Commitments and Contingencies [Line Items] | |||
Indemnifications, renewable tax credit transfers | 76 | ||
Indemnification Agreement [Member] | Renewable Tax Credits Transferred [Member] | WPL [Member] | |||
Commitments and Contingencies [Line Items] | |||
Indemnifications, renewable tax credit transfers | $ 22 | ||
Workforce Subject to Collective Bargaining Arrangements [Member] | |||
Commitments and Contingencies [Line Items] | |||
Employees covered by collective bargaining agreement, percentage | 53% | ||
Workforce Subject to Collective Bargaining Arrangements [Member] | IPL [Member] | |||
Commitments and Contingencies [Line Items] | |||
Employees covered by collective bargaining agreement, percentage | 70% | ||
Workforce Subject to Collective Bargaining Arrangements [Member] | WPL [Member] | |||
Commitments and Contingencies [Line Items] | |||
Employees covered by collective bargaining agreement, percentage | 83% | ||
Workforce Subject to Collective Bargaining Arrangements Expiring within One Year [Member] | |||
Commitments and Contingencies [Line Items] | |||
Employees covered by collective bargaining agreement, percentage | 18% | ||
Workforce Subject to Collective Bargaining Arrangements Expiring within One Year [Member] | IPL [Member] | |||
Commitments and Contingencies [Line Items] | |||
Employees covered by collective bargaining agreement, percentage | 53% | ||
Whiting Petroleum Affiliate [Member] | |||
Commitments and Contingencies [Line Items] | |||
Partnership share, percent | 6% | ||
Obligations, maximum | $ 49 | ||
Federal Energy Regulatory Commission [Member] | |||
Commitments and Contingencies [Line Items] | |||
MISO base return on equity, percentage | 10.02% | 9.88% |
Commitments And Contingencies_3
Commitments And Contingencies (Other Purchase Commitments) (Details) $ in Millions | 3 Months Ended |
Mar. 31, 2024 USD ($) | |
Commitments and Contingencies [Line Items] | |
Minimum future commitments | $ 1,098 |
Individual commitments incurred | 1 |
IPL [Member] | |
Commitments and Contingencies [Line Items] | |
Minimum future commitments | 497 |
Individual commitments incurred | 1 |
WPL [Member] | |
Commitments and Contingencies [Line Items] | |
Minimum future commitments | 554 |
Individual commitments incurred | 1 |
Natural gas [Member] | |
Commitments and Contingencies [Line Items] | |
Minimum future commitments | 807 |
Natural gas [Member] | IPL [Member] | |
Commitments and Contingencies [Line Items] | |
Minimum future commitments | 335 |
Natural gas [Member] | WPL [Member] | |
Commitments and Contingencies [Line Items] | |
Minimum future commitments | 472 |
Coal [Member] | |
Commitments and Contingencies [Line Items] | |
Minimum future commitments | 167 |
Coal [Member] | IPL [Member] | |
Commitments and Contingencies [Line Items] | |
Minimum future commitments | 110 |
Coal [Member] | WPL [Member] | |
Commitments and Contingencies [Line Items] | |
Minimum future commitments | 57 |
Other [Member] | |
Commitments and Contingencies [Line Items] | |
Minimum future commitments | 124 |
Other [Member] | IPL [Member] | |
Commitments and Contingencies [Line Items] | |
Minimum future commitments | 52 |
Other [Member] | WPL [Member] | |
Commitments and Contingencies [Line Items] | |
Minimum future commitments | $ 25 |
Commitments And Contingencies_4
Commitments And Contingencies (MPG Site Estimated Future Costs And Recorded Liabilities) (Details) - Natural Gas Processing Plant [Member] $ in Millions | 3 Months Ended |
Mar. 31, 2024 USD ($) | |
Commitments and Contingencies [Line Items] | |
Current and non-current environmental liabilities | $ 13 |
IPL [Member] | |
Commitments and Contingencies [Line Items] | |
Current and non-current environmental liabilities | 8 |
WPL [Member] | |
Commitments and Contingencies [Line Items] | |
Current and non-current environmental liabilities | 5 |
Minimum [Member] | |
Commitments and Contingencies [Line Items] | |
Range of estimated future costs | 8 |
Minimum [Member] | IPL [Member] | |
Commitments and Contingencies [Line Items] | |
Range of estimated future costs | 6 |
Minimum [Member] | WPL [Member] | |
Commitments and Contingencies [Line Items] | |
Range of estimated future costs | 2 |
Maximum [Member] | |
Commitments and Contingencies [Line Items] | |
Range of estimated future costs | 29 |
Maximum [Member] | IPL [Member] | |
Commitments and Contingencies [Line Items] | |
Range of estimated future costs | 18 |
Maximum [Member] | WPL [Member] | |
Commitments and Contingencies [Line Items] | |
Range of estimated future costs | $ 11 |
Segments Of Business (Schedule
Segments Of Business (Schedule Of Segments Of Business) (Details) - USD ($) $ in Millions | 3 Months Ended | |
Mar. 31, 2024 | Mar. 31, 2023 | |
Segment Reporting Information [Line Items] | ||
Revenues | $ 1,031 | $ 1,077 |
Operating income (loss) | 222 | 222 |
Net income (loss) attributable to common shareowners | 158 | 163 |
Net income | 158 | 163 |
IPL [Member] | ||
Segment Reporting Information [Line Items] | ||
Revenues | 513 | 549 |
Operating income (loss) | 85 | 96 |
Net income | 63 | 72 |
WPL [Member] | ||
Segment Reporting Information [Line Items] | ||
Revenues | 496 | 506 |
Operating income (loss) | 131 | 121 |
Net income | 92 | 88 |
Electric [Member] | ||
Segment Reporting Information [Line Items] | ||
Revenues | 791 | 768 |
Operating income (loss) | 164 | 163 |
Electric [Member] | IPL [Member] | ||
Segment Reporting Information [Line Items] | ||
Revenues | 392 | 388 |
Operating income (loss) | 57 | 66 |
Electric [Member] | WPL [Member] | ||
Segment Reporting Information [Line Items] | ||
Revenues | 399 | 380 |
Operating income (loss) | 107 | 97 |
Gas [Member] | ||
Segment Reporting Information [Line Items] | ||
Revenues | 205 | 276 |
Operating income (loss) | 47 | 50 |
Gas [Member] | IPL [Member] | ||
Segment Reporting Information [Line Items] | ||
Revenues | 108 | 150 |
Operating income (loss) | 22 | 27 |
Gas [Member] | WPL [Member] | ||
Segment Reporting Information [Line Items] | ||
Revenues | 97 | 126 |
Operating income (loss) | 25 | 23 |
Other Utility [Member] | ||
Segment Reporting Information [Line Items] | ||
Revenues | 13 | 11 |
Operating income (loss) | 5 | 4 |
Other Utility [Member] | IPL [Member] | ||
Segment Reporting Information [Line Items] | ||
Revenues | 13 | 11 |
Operating income (loss) | 6 | 3 |
Other Utility [Member] | WPL [Member] | ||
Segment Reporting Information [Line Items] | ||
Revenues | 0 | 0 |
Operating income (loss) | (1) | 1 |
Non-utility and Other [Member] | ||
Segment Reporting Information [Line Items] | ||
Revenues | 22 | 22 |
Operating income (loss) | 6 | 5 |
Net income (loss) attributable to common shareowners | 3 | 3 |
Utility Business [Member] | ||
Segment Reporting Information [Line Items] | ||
Revenues | 1,009 | 1,055 |
Operating income (loss) | 216 | 217 |
Net income (loss) attributable to common shareowners | $ 155 | $ 160 |
Related Parties (Narrative) (De
Related Parties (Narrative) (Details) - USD ($) $ in Millions | Mar. 31, 2024 | Dec. 31, 2023 |
WPL [Member] | WPL Owed ATC LLC [Member] | Related Party [Member] | ||
Related Party Transactions [Line Items] | ||
Net amounts owed | $ 10 | $ 10 |
Related Parties (Service Agreem
Related Parties (Service Agreements) (Details) - Corporate Services [Member] - Subsidiary of Common Parent [Member] - USD ($) $ in Millions | 3 Months Ended | |
Mar. 31, 2024 | Mar. 31, 2023 | |
Corporate Services Billings [Member] | IPL [Member] | ||
Related Party Transactions [Line Items] | ||
Amounts billed between related parties | $ 43 | $ 40 |
Corporate Services Billings [Member] | WPL [Member] | ||
Related Party Transactions [Line Items] | ||
Amounts billed between related parties | 40 | 36 |
Sales Credited [Member] | IPL [Member] | ||
Related Party Transactions [Line Items] | ||
Amounts billed between related parties | 0 | 7 |
Sales Credited [Member] | WPL [Member] | ||
Related Party Transactions [Line Items] | ||
Amounts billed between related parties | 22 | 13 |
Purchases Billed [Member] | IPL [Member] | ||
Related Party Transactions [Line Items] | ||
Amounts billed between related parties | 96 | 93 |
Purchases Billed [Member] | WPL [Member] | ||
Related Party Transactions [Line Items] | ||
Amounts billed between related parties | $ 7 | $ 15 |
Related Parties (Net Intercompa
Related Parties (Net Intercompany Payables) (Details) - Related Party [Member] - Corporate Services [Member] - USD ($) $ in Millions | Mar. 31, 2024 | Dec. 31, 2023 |
IPL [Member] | ||
Related Party Transactions [Line Items] | ||
Net amounts owed | $ 132 | $ 129 |
WPL [Member] | ||
Related Party Transactions [Line Items] | ||
Net amounts owed | $ 70 | $ 72 |
Related Parties (Amounts Billed
Related Parties (Amounts Billed Between Parties) (Details) - ATC LLC [Member] - WPL [Member] - USD ($) $ in Millions | 3 Months Ended | |
Mar. 31, 2024 | Mar. 31, 2023 | |
ATC Billings To WPL [Member] | ||
Related Party Transactions [Line Items] | ||
Amounts billed between related parties | $ 37 | $ 34 |
WPL Billings To ATC [Member] | ||
Related Party Transactions [Line Items] | ||
Amounts billed between related parties | $ 3 | $ 6 |