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Segments Of Business | 12 Months Ended
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Dec. 31, 2023
Segment Reporting Information [Line Items] |
Segments Of Business | SEGMENTS OF BUSINESS Alliant Energy - Alliant Energy’s principal businesses as of December 31, 2023 are: •Utility - includes the operations of IPL and WPL, which primarily serve retail customers in Iowa and Wisconsin. The utility business has three reportable segments: a) utility electric operations; b) utility gas operations; and c) utility other, which includes steam operations and the unallocated portions of the utility business. Various line items in the following tables are not allocated to the electric and gas segments for management reporting purposes, and therefore, are included only in “Total Utility.” •ATC Holdings, Non-utility, Parent and Other - includes the operations of AEF and its subsidiaries, Corporate Services, the Alliant Energy parent company, and any Alliant Energy parent company consolidating adjustments. AEF is comprised of Alliant Energy’s interest in ATC Holdings, Travero, a non-utility wind farm, corporate venture investments, the Sheboygan Falls Energy Facility and other non-utility holdings. Alliant Energy’s administrative support services are directly charged to the applicable segment where practicable. In all other cases, administrative support services are allocated to the applicable segment based on services agreements. Intersegment revenues were not material to Alliant Energy’s operations and there was no single customer whose revenues were 10% or more of Alliant Energy’s consolidated revenues. All of Alliant Energy’s operations and assets are located in the U.S. Certain financial information relating to Alliant Energy’s business segments, which represent the services provided to its customers, was as follows (in millions):
|  |  |  |  |  |  |  |  | ATC Holdings, |  |
| Utility |  | Non-utility, |  | Alliant Energy
2023 | Electric |  | Gas |  | Other |  | Total |  | Parent and Other |  | Consolidated
Revenues | $3,345 |  |  | $540 |  |  | $52 |  |  | $3,937 |  |  | $90 |  | $4,027
Depreciation and amortization | 602 |  |  | 60 |  |  | 6 |  |  | 668 |  |  | 8 |  | 676
Operating income | 827 |  |  | 70 |  |  | 19 |  |  | 916 |  |  | 27 |  | 943
Interest expense |  |  |  |  |  |  | 304 |  |  | 90 |  | 394
Equity income from unconsolidated investments, net | (3) |  |  | — |  |  | — |  |  | (3) |  |  | (58) |  | (61)
Income taxes |  |  |  |  |  |  | 2 |  |  | 2 |  | 4
Net income (loss) attributable to Alliant Energy common shareowners |  |  |  |  |  |  | 711 |  |  | (8) |  | 703
Total assets | 17,833 |  |  | 1,684 |  |  | 606 |  |  | 20,123 |  |  | 1,114 |  | 21,237
Investments in equity method subsidiaries | 21 |  |  | — |  |  | — |  |  | 21 |  |  | 564 |  | 585
Construction and acquisition expenditures | 1,641 |  |  | 90 |  |  | — |  |  | 1,731 |  |  | 123 |  | 1,854
|  |  |  |  |  |  |  |  | ATC Holdings, |  |
| Utility |  | Non-utility, |  | Alliant Energy
2022 | Electric |  | Gas |  | Other |  | Total |  | Parent and Other |  | Consolidated
Revenues | $3,421 |  |  | $642 |  |  | $49 |  |  | $4,112 |  |  | $93 |  | $4,205
Depreciation and amortization | 601 |  |  | 56 |  |  | 7 |  |  | 664 |  |  | 7 |  | 671
Operating income | 805 |  |  | 97 |  |  | 3 |  |  | 905 |  |  | 23 |  | 928
Interest expense |  |  |  |  |  |  | 269 |  |  | 56 |  | 325
Equity income from unconsolidated investments, net | (1) |  |  | — |  |  | — |  |  | (1) |  |  | (50) |  | (51)
Income taxes |  |  |  |  |  |  | 16 |  |  | 6 |  | 22
Net income attributable to Alliant Energy common shareowners |  |  |  |  |  |  | 675 |  |  | 11 |  | 686
Total assets | 16,571 |  |  | 1,631 |  |  | 860 |  |  | 19,062 |  |  | 1,101 |  | 20,163
Investments in equity method subsidiaries | 20 |  |  | — |  |  | — |  |  | 20 |  |  | 522 |  | 542
Construction and acquisition expenditures | 1,318 |  |  | 74 |  |  | — |  |  | 1,392 |  |  | 92 |  | 1,484
|  |  |  |  |  |  |  |  | ATC Holdings, |  |
| Utility |  | Non-utility, |  | Alliant Energy
2021 | Electric |  | Gas |  | Other |  | Total |  | Parent and Other |  | Consolidated
Revenues | $3,081 |  |  | $456 |  |  | $49 |  |  | $3,586 |  |  | $83 |  | $3,669
Depreciation and amortization | 591 |  |  | 54 |  |  | 6 |  |  | 651 |  |  | 6 |  | 657
Operating income (loss) | 716 |  |  | 63 |  |  | (11) |  |  | 768 |  |  | 27 |  | 795
Interest expense |  |  |  |  |  |  | 244 |  |  | 33 |  | 277
Equity income from unconsolidated investments, net | (2) |  |  | — |  |  | — |  |  | (2) |  |  | (60) |  | (62)
Income tax expense (benefit) |  |  |  |  |  |  | (87) |  |  | 13 |  | (74)
Net income attributable to Alliant Energy common shareowners |  |  |  |  |  |  | 618 |  |  | 41 |  | 659
Total assets | 14,924 |  |  | 1,487 |  |  | 1,103 |  |  | 17,514 |  |  | 1,039 |  | 18,553
Investments in equity method subsidiaries | 17 |  |  | — |  |  | — |  |  | 17 |  |  | 491 |  | 508
Construction and acquisition expenditures | 980 |  |  | 90 |  |  | — |  |  | 1,070 |  |  | 99 |  | 1,169
IPL - IPL is a utility primarily serving retail customers in Iowa and includes three reportable segments: a) electric operations; b) gas operations; and c) other, which includes steam operations and the unallocated portions of the utility business. Various line items in the following tables are not allocated to the electric and gas segments for management reporting purposes, and therefore, are included only in “Total.” Intersegment revenues were not material to IPL’s operations and there was no single customer whose revenues were 10% or more of IPL’s consolidated revenues. All of IPL’s operations and assets are located in the U.S. Certain financial information relating to IPL’s business segments, which represent the services provided to its customers, was as follows (in millions):
2023 | Electric |  | Gas |  | Other |  | Total
Revenues | $1,761 |  | $300 |  | $49 |  | $2,110 |
Depreciation and amortization | 348 |  | 34 |  | 6 |  | 388 |
Operating income | 390 |  | 35 |  | 19 |  | 444 |
Interest expense |  |  |  |  |  |  | 155 |
Income tax benefit |  |  |  |  |  |  | (58) |
Net income available for common stock |  |  |  |  |  |  | 366 |
Total assets | 9,311 |  |  | 921 |  |  | 257 |  |  | 10,489 |
Construction and acquisition expenditures | 671 |  |  | 41 |  |  | — |  |  | 712 |
2022 | Electric |  | Gas |  | Other |  | Total
Revenues | $1,859 |  |  | $351 |  |  | $46 |  |  | $2,256 |
Depreciation and amortization | 342 |  |  | 32 |  |  | 7 |  |  | 381 |
Operating income | 397 |  |  | 53 |  |  | 3 |  |  | 453 |
Interest expense |  |  |  |  |  |  | 148 |
Income tax benefit |  |  |  |  |  |  | (50) |
Net income available for common stock |  |  |  |  |  |  | 360 |
Total assets | 8,686 |  |  | 872 |  |  | 517 |  |  | 10,075 |
Construction and acquisition expenditures | 336 |  |  | 36 |  |  | — |  |  | 372 |
2021 | Electric |  | Gas |  | Other |  | Total
Revenues | $1,752 |  |  | $265 |  |  | $46 |  |  | $2,063 |
Depreciation and amortization | 338 |  |  | 31 |  |  | 6 |  |  | 375 |
Operating income (loss) | 420 |  |  | 43 |  |  | (3) |  |  | 460 |
Interest expense |  |  |  |  |  |  | 139 |
Income tax benefit |  |  |  |  |  |  | (36) |
Net income available for common stock |  |  |  |  |  |  | 350 |
Total assets | 8,602 |  |  | 819 |  |  | 575 |  |  | 9,996 |
Construction and acquisition expenditures | 342 |  |  | 42 |  |  | — |  |  | 384 |
WPL - WPL is a utility serving customers in Wisconsin and includes three reportable segments: a) electric operations; b) gas operations; and c) other, which includes the unallocated portions of the utility business. Various line items in the following tables are not allocated to the electric and gas segments for management reporting purposes, and therefore, are included only in “Total.” Intersegment revenues were not material to WPL’s operations and there was no single customer whose revenues were 10% or more of WPL’s consolidated revenues. All of WPL’s operations and assets are located in the U.S. Certain financial information relating to WPL’s business segments, which represent the services provided to its customers, was as follows (in millions):
2023 | Electric |  | Gas |  | Other |  | Total
Revenues | $1,584 |  |  | $240 |  |  | $3 |  |  | $1,827 |
Depreciation and amortization | 254 |  |  | 26 |  |  | — |  |  | 280 |
Operating income | 437 |  |  | 35 |  |  | — |  |  | 472 |
Interest expense |  |  |  |  |  |  | 149 |
Income taxes |  |  |  |  |  |  | 60 |
Net income |  |  |  |  |  |  | 345 |
Total assets | 8,522 |  |  | 763 |  |  | 349 |  |  | 9,634 |
Construction and acquisition expenditures | 970 |  |  | 49 |  |  | — |  |  | 1,019 |
2022 | Electric |  | Gas |  | Other |  | Total
Revenues | $1,562 |  |  | $291 |  |  | $3 |  |  | $1,856 |
Depreciation and amortization | 259 |  |  | 24 |  |  | — |  |  | 283 |
Operating income | 408 |  |  | 44 |  |  | — |  |  | 452 |
Interest expense |  |  |  |  |  |  | 121 |
Income taxes |  |  |  |  |  |  | 66 |
Net income |  |  |  |  |  |  | 315 |
Total assets | 7,885 |  |  | 759 |  |  | 343 |  |  | 8,987 |
Construction and acquisition expenditures | 982 |  |  | 38 |  |  | — |  |  | 1,020 |
2021 | Electric |  | Gas |  | Other |  | Total
Revenues | $1,329 |  |  | $191 |  |  | $3 |  |  | $1,523 |
Depreciation and amortization | 253 |  |  | 23 |  |  | — |  |  | 276 |
Operating income (loss) | 296 |  |  | 20 |  |  | (8) |  |  | 308 |
Interest expense |  |  |  |  |  |  | 105 |
Income tax benefit |  |  |  |  |  |  | (51) |
Net income |  |  |  |  |  |  | 268 |
Total assets | 6,322 |  |  | 668 |  |  | 528 |  |  | 7,518 |
Construction and acquisition expenditures | 638 |  |  | 48 |  |  | — |  |  | 686 |
IPL [Member] |
Segment Reporting Information [Line Items] |
Segments Of Business | SEGMENTS OF BUSINESS Alliant Energy - Alliant Energy’s principal businesses as of December 31, 2023 are: •Utility - includes the operations of IPL and WPL, which primarily serve retail customers in Iowa and Wisconsin. The utility business has three reportable segments: a) utility electric operations; b) utility gas operations; and c) utility other, which includes steam operations and the unallocated portions of the utility business. Various line items in the following tables are not allocated to the electric and gas segments for management reporting purposes, and therefore, are included only in “Total Utility.” •ATC Holdings, Non-utility, Parent and Other - includes the operations of AEF and its subsidiaries, Corporate Services, the Alliant Energy parent company, and any Alliant Energy parent company consolidating adjustments. AEF is comprised of Alliant Energy’s interest in ATC Holdings, Travero, a non-utility wind farm, corporate venture investments, the Sheboygan Falls Energy Facility and other non-utility holdings. Alliant Energy’s administrative support services are directly charged to the applicable segment where practicable. In all other cases, administrative support services are allocated to the applicable segment based on services agreements. Intersegment revenues were not material to Alliant Energy’s operations and there was no single customer whose revenues were 10% or more of Alliant Energy’s consolidated revenues. All of Alliant Energy’s operations and assets are located in the U.S. Certain financial information relating to Alliant Energy’s business segments, which represent the services provided to its customers, was as follows (in millions):
|  |  |  |  |  |  |  |  | ATC Holdings, |  |
| Utility |  | Non-utility, |  | Alliant Energy
2023 | Electric |  | Gas |  | Other |  | Total |  | Parent and Other |  | Consolidated
Revenues | $3,345 |  |  | $540 |  |  | $52 |  |  | $3,937 |  |  | $90 |  | $4,027
Depreciation and amortization | 602 |  |  | 60 |  |  | 6 |  |  | 668 |  |  | 8 |  | 676
Operating income | 827 |  |  | 70 |  |  | 19 |  |  | 916 |  |  | 27 |  | 943
Interest expense |  |  |  |  |  |  | 304 |  |  | 90 |  | 394
Equity income from unconsolidated investments, net | (3) |  |  | — |  |  | — |  |  | (3) |  |  | (58) |  | (61)
Income taxes |  |  |  |  |  |  | 2 |  |  | 2 |  | 4
Net income (loss) attributable to Alliant Energy common shareowners |  |  |  |  |  |  | 711 |  |  | (8) |  | 703
Total assets | 17,833 |  |  | 1,684 |  |  | 606 |  |  | 20,123 |  |  | 1,114 |  | 21,237
Investments in equity method subsidiaries | 21 |  |  | — |  |  | — |  |  | 21 |  |  | 564 |  | 585
Construction and acquisition expenditures | 1,641 |  |  | 90 |  |  | — |  |  | 1,731 |  |  | 123 |  | 1,854
|  |  |  |  |  |  |  |  | ATC Holdings, |  |
| Utility |  | Non-utility, |  | Alliant Energy
2022 | Electric |  | Gas |  | Other |  | Total |  | Parent and Other |  | Consolidated
Revenues | $3,421 |  |  | $642 |  |  | $49 |  |  | $4,112 |  |  | $93 |  | $4,205
Depreciation and amortization | 601 |  |  | 56 |  |  | 7 |  |  | 664 |  |  | 7 |  | 671
Operating income | 805 |  |  | 97 |  |  | 3 |  |  | 905 |  |  | 23 |  | 928
Interest expense |  |  |  |  |  |  | 269 |  |  | 56 |  | 325
Equity income from unconsolidated investments, net | (1) |  |  | — |  |  | — |  |  | (1) |  |  | (50) |  | (51)
Income taxes |  |  |  |  |  |  | 16 |  |  | 6 |  | 22
Net income attributable to Alliant Energy common shareowners |  |  |  |  |  |  | 675 |  |  | 11 |  | 686
Total assets | 16,571 |  |  | 1,631 |  |  | 860 |  |  | 19,062 |  |  | 1,101 |  | 20,163
Investments in equity method subsidiaries | 20 |  |  | — |  |  | — |  |  | 20 |  |  | 522 |  | 542
Construction and acquisition expenditures | 1,318 |  |  | 74 |  |  | — |  |  | 1,392 |  |  | 92 |  | 1,484
|  |  |  |  |  |  |  |  | ATC Holdings, |  |
| Utility |  | Non-utility, |  | Alliant Energy
2021 | Electric |  | Gas |  | Other |  | Total |  | Parent and Other |  | Consolidated
Revenues | $3,081 |  |  | $456 |  |  | $49 |  |  | $3,586 |  |  | $83 |  | $3,669
Depreciation and amortization | 591 |  |  | 54 |  |  | 6 |  |  | 651 |  |  | 6 |  | 657
Operating income (loss) | 716 |  |  | 63 |  |  | (11) |  |  | 768 |  |  | 27 |  | 795
Interest expense |  |  |  |  |  |  | 244 |  |  | 33 |  | 277
Equity income from unconsolidated investments, net | (2) |  |  | — |  |  | — |  |  | (2) |  |  | (60) |  | (62)
Income tax expense (benefit) |  |  |  |  |  |  | (87) |  |  | 13 |  | (74)
Net income attributable to Alliant Energy common shareowners |  |  |  |  |  |  | 618 |  |  | 41 |  | 659
Total assets | 14,924 |  |  | 1,487 |  |  | 1,103 |  |  | 17,514 |  |  | 1,039 |  | 18,553
Investments in equity method subsidiaries | 17 |  |  | — |  |  | — |  |  | 17 |  |  | 491 |  | 508
Construction and acquisition expenditures | 980 |  |  | 90 |  |  | — |  |  | 1,070 |  |  | 99 |  | 1,169
IPL - IPL is a utility primarily serving retail customers in Iowa and includes three reportable segments: a) electric operations; b) gas operations; and c) other, which includes steam operations and the unallocated portions of the utility business. Various line items in the following tables are not allocated to the electric and gas segments for management reporting purposes, and therefore, are included only in “Total.” Intersegment revenues were not material to IPL’s operations and there was no single customer whose revenues were 10% or more of IPL’s consolidated revenues. All of IPL’s operations and assets are located in the U.S. Certain financial information relating to IPL’s business segments, which represent the services provided to its customers, was as follows (in millions):
2023 | Electric |  | Gas |  | Other |  | Total
Revenues | $1,761 |  | $300 |  | $49 |  | $2,110 |
Depreciation and amortization | 348 |  | 34 |  | 6 |  | 388 |
Operating income | 390 |  | 35 |  | 19 |  | 444 |
Interest expense |  |  |  |  |  |  | 155 |
Income tax benefit |  |  |  |  |  |  | (58) |
Net income available for common stock |  |  |  |  |  |  | 366 |
Total assets | 9,311 |  |  | 921 |  |  | 257 |  |  | 10,489 |
Construction and acquisition expenditures | 671 |  |  | 41 |  |  | — |  |  | 712 |
2022 | Electric |  | Gas |  | Other |  | Total
Revenues | $1,859 |  |  | $351 |  |  | $46 |  |  | $2,256 |
Depreciation and amortization | 342 |  |  | 32 |  |  | 7 |  |  | 381 |
Operating income | 397 |  |  | 53 |  |  | 3 |  |  | 453 |
Interest expense |  |  |  |  |  |  | 148 |
Income tax benefit |  |  |  |  |  |  | (50) |
Net income available for common stock |  |  |  |  |  |  | 360 |
Total assets | 8,686 |  |  | 872 |  |  | 517 |  |  | 10,075 |
Construction and acquisition expenditures | 336 |  |  | 36 |  |  | — |  |  | 372 |
2021 | Electric |  | Gas |  | Other |  | Total
Revenues | $1,752 |  |  | $265 |  |  | $46 |  |  | $2,063 |
Depreciation and amortization | 338 |  |  | 31 |  |  | 6 |  |  | 375 |
Operating income (loss) | 420 |  |  | 43 |  |  | (3) |  |  | 460 |
Interest expense |  |  |  |  |  |  | 139 |
Income tax benefit |  |  |  |  |  |  | (36) |
Net income available for common stock |  |  |  |  |  |  | 350 |
Total assets | 8,602 |  |  | 819 |  |  | 575 |  |  | 9,996 |
Construction and acquisition expenditures | 342 |  |  | 42 |  |  | — |  |  | 384 |
WPL - WPL is a utility serving customers in Wisconsin and includes three reportable segments: a) electric operations; b) gas operations; and c) other, which includes the unallocated portions of the utility business. Various line items in the following tables are not allocated to the electric and gas segments for management reporting purposes, and therefore, are included only in “Total.” Intersegment revenues were not material to WPL’s operations and there was no single customer whose revenues were 10% or more of WPL’s consolidated revenues. All of WPL’s operations and assets are located in the U.S. Certain financial information relating to WPL’s business segments, which represent the services provided to its customers, was as follows (in millions):
2023 | Electric |  | Gas |  | Other |  | Total
Revenues | $1,584 |  |  | $240 |  |  | $3 |  |  | $1,827 |
Depreciation and amortization | 254 |  |  | 26 |  |  | — |  |  | 280 |
Operating income | 437 |  |  | 35 |  |  | — |  |  | 472 |
Interest expense |  |  |  |  |  |  | 149 |
Income taxes |  |  |  |  |  |  | 60 |
Net income |  |  |  |  |  |  | 345 |
Total assets | 8,522 |  |  | 763 |  |  | 349 |  |  | 9,634 |
Construction and acquisition expenditures | 970 |  |  | 49 |  |  | — |  |  | 1,019 |
2022 | Electric |  | Gas |  | Other |  | Total
Revenues | $1,562 |  |  | $291 |  |  | $3 |  |  | $1,856 |
Depreciation and amortization | 259 |  |  | 24 |  |  | — |  |  | 283 |
Operating income | 408 |  |  | 44 |  |  | — |  |  | 452 |
Interest expense |  |  |  |  |  |  | 121 |
Income taxes |  |  |  |  |  |  | 66 |
Net income |  |  |  |  |  |  | 315 |
Total assets | 7,885 |  |  | 759 |  |  | 343 |  |  | 8,987 |
Construction and acquisition expenditures | 982 |  |  | 38 |  |  | — |  |  | 1,020 |
2021 | Electric |  | Gas |  | Other |  | Total
Revenues | $1,329 |  |  | $191 |  |  | $3 |  |  | $1,523 |
Depreciation and amortization | 253 |  |  | 23 |  |  | — |  |  | 276 |
Operating income (loss) | 296 |  |  | 20 |  |  | (8) |  |  | 308 |
Interest expense |  |  |  |  |  |  | 105 |
Income tax benefit |  |  |  |  |  |  | (51) |
Net income |  |  |  |  |  |  | 268 |
Total assets | 6,322 |  |  | 668 |  |  | 528 |  |  | 7,518 |
Construction and acquisition expenditures | 638 |  |  | 48 |  |  | — |  |  | 686 |
WPL [Member] |
Segment Reporting Information [Line Items] |
Segments Of Business | SEGMENTS OF BUSINESS Alliant Energy - Alliant Energy’s principal businesses as of December 31, 2023 are: •Utility - includes the operations of IPL and WPL, which primarily serve retail customers in Iowa and Wisconsin. The utility business has three reportable segments: a) utility electric operations; b) utility gas operations; and c) utility other, which includes steam operations and the unallocated portions of the utility business. Various line items in the following tables are not allocated to the electric and gas segments for management reporting purposes, and therefore, are included only in “Total Utility.” •ATC Holdings, Non-utility, Parent and Other - includes the operations of AEF and its subsidiaries, Corporate Services, the Alliant Energy parent company, and any Alliant Energy parent company consolidating adjustments. AEF is comprised of Alliant Energy’s interest in ATC Holdings, Travero, a non-utility wind farm, corporate venture investments, the Sheboygan Falls Energy Facility and other non-utility holdings. Alliant Energy’s administrative support services are directly charged to the applicable segment where practicable. In all other cases, administrative support services are allocated to the applicable segment based on services agreements. Intersegment revenues were not material to Alliant Energy’s operations and there was no single customer whose revenues were 10% or more of Alliant Energy’s consolidated revenues. All of Alliant Energy’s operations and assets are located in the U.S. Certain financial information relating to Alliant Energy’s business segments, which represent the services provided to its customers, was as follows (in millions):
|  |  |  |  |  |  |  |  | ATC Holdings, |  |
| Utility |  | Non-utility, |  | Alliant Energy
2023 | Electric |  | Gas |  | Other |  | Total |  | Parent and Other |  | Consolidated
Revenues | $3,345 |  |  | $540 |  |  | $52 |  |  | $3,937 |  |  | $90 |  | $4,027
Depreciation and amortization | 602 |  |  | 60 |  |  | 6 |  |  | 668 |  |  | 8 |  | 676
Operating income | 827 |  |  | 70 |  |  | 19 |  |  | 916 |  |  | 27 |  | 943
Interest expense |  |  |  |  |  |  | 304 |  |  | 90 |  | 394
Equity income from unconsolidated investments, net | (3) |  |  | — |  |  | — |  |  | (3) |  |  | (58) |  | (61)
Income taxes |  |  |  |  |  |  | 2 |  |  | 2 |  | 4
Net income (loss) attributable to Alliant Energy common shareowners |  |  |  |  |  |  | 711 |  |  | (8) |  | 703
Total assets | 17,833 |  |  | 1,684 |  |  | 606 |  |  | 20,123 |  |  | 1,114 |  | 21,237
Investments in equity method subsidiaries | 21 |  |  | — |  |  | — |  |  | 21 |  |  | 564 |  | 585
Construction and acquisition expenditures | 1,641 |  |  | 90 |  |  | — |  |  | 1,731 |  |  | 123 |  | 1,854
|  |  |  |  |  |  |  |  | ATC Holdings, |  |
| Utility |  | Non-utility, |  | Alliant Energy
2022 | Electric |  | Gas |  | Other |  | Total |  | Parent and Other |  | Consolidated
Revenues | $3,421 |  |  | $642 |  |  | $49 |  |  | $4,112 |  |  | $93 |  | $4,205
Depreciation and amortization | 601 |  |  | 56 |  |  | 7 |  |  | 664 |  |  | 7 |  | 671
Operating income | 805 |  |  | 97 |  |  | 3 |  |  | 905 |  |  | 23 |  | 928
Interest expense |  |  |  |  |  |  | 269 |  |  | 56 |  | 325
Equity income from unconsolidated investments, net | (1) |  |  | — |  |  | — |  |  | (1) |  |  | (50) |  | (51)
Income taxes |  |  |  |  |  |  | 16 |  |  | 6 |  | 22
Net income attributable to Alliant Energy common shareowners |  |  |  |  |  |  | 675 |  |  | 11 |  | 686
Total assets | 16,571 |  |  | 1,631 |  |  | 860 |  |  | 19,062 |  |  | 1,101 |  | 20,163
Investments in equity method subsidiaries | 20 |  |  | — |  |  | — |  |  | 20 |  |  | 522 |  | 542
Construction and acquisition expenditures | 1,318 |  |  | 74 |  |  | — |  |  | 1,392 |  |  | 92 |  | 1,484
|  |  |  |  |  |  |  |  | ATC Holdings, |  |
| Utility |  | Non-utility, |  | Alliant Energy
2021 | Electric |  | Gas |  | Other |  | Total |  | Parent and Other |  | Consolidated
Revenues | $3,081 |  |  | $456 |  |  | $49 |  |  | $3,586 |  |  | $83 |  | $3,669
Depreciation and amortization | 591 |  |  | 54 |  |  | 6 |  |  | 651 |  |  | 6 |  | 657
Operating income (loss) | 716 |  |  | 63 |  |  | (11) |  |  | 768 |  |  | 27 |  | 795
Interest expense |  |  |  |  |  |  | 244 |  |  | 33 |  | 277
Equity income from unconsolidated investments, net | (2) |  |  | — |  |  | — |  |  | (2) |  |  | (60) |  | (62)
Income tax expense (benefit) |  |  |  |  |  |  | (87) |  |  | 13 |  | (74)
Net income attributable to Alliant Energy common shareowners |  |  |  |  |  |  | 618 |  |  | 41 |  | 659
Total assets | 14,924 |  |  | 1,487 |  |  | 1,103 |  |  | 17,514 |  |  | 1,039 |  | 18,553
Investments in equity method subsidiaries | 17 |  |  | — |  |  | — |  |  | 17 |  |  | 491 |  | 508
Construction and acquisition expenditures | 980 |  |  | 90 |  |  | — |  |  | 1,070 |  |  | 99 |  | 1,169
IPL - IPL is a utility primarily serving retail customers in Iowa and includes three reportable segments: a) electric operations; b) gas operations; and c) other, which includes steam operations and the unallocated portions of the utility business. Various line items in the following tables are not allocated to the electric and gas segments for management reporting purposes, and therefore, are included only in “Total.” Intersegment revenues were not material to IPL’s operations and there was no single customer whose revenues were 10% or more of IPL’s consolidated revenues. All of IPL’s operations and assets are located in the U.S. Certain financial information relating to IPL’s business segments, which represent the services provided to its customers, was as follows (in millions):
2023 | Electric |  | Gas |  | Other |  | Total
Revenues | $1,761 |  | $300 |  | $49 |  | $2,110 |
Depreciation and amortization | 348 |  | 34 |  | 6 |  | 388 |
Operating income | 390 |  | 35 |  | 19 |  | 444 |
Interest expense |  |  |  |  |  |  | 155 |
Income tax benefit |  |  |  |  |  |  | (58) |
Net income available for common stock |  |  |  |  |  |  | 366 |
Total assets | 9,311 |  |  | 921 |  |  | 257 |  |  | 10,489 |
Construction and acquisition expenditures | 671 |  |  | 41 |  |  | — |  |  | 712 |
2022 | Electric |  | Gas |  | Other |  | Total
Revenues | $1,859 |  |  | $351 |  |  | $46 |  |  | $2,256 |
Depreciation and amortization | 342 |  |  | 32 |  |  | 7 |  |  | 381 |
Operating income | 397 |  |  | 53 |  |  | 3 |  |  | 453 |
Interest expense |  |  |  |  |  |  | 148 |
Income tax benefit |  |  |  |  |  |  | (50) |
Net income available for common stock |  |  |  |  |  |  | 360 |
Total assets | 8,686 |  |  | 872 |  |  | 517 |  |  | 10,075 |
Construction and acquisition expenditures | 336 |  |  | 36 |  |  | — |  |  | 372 |
2021 | Electric |  | Gas |  | Other |  | Total
Revenues | $1,752 |  |  | $265 |  |  | $46 |  |  | $2,063 |
Depreciation and amortization | 338 |  |  | 31 |  |  | 6 |  |  | 375 |
Operating income (loss) | 420 |  |  | 43 |  |  | (3) |  |  | 460 |
Interest expense |  |  |  |  |  |  | 139 |
Income tax benefit |  |  |  |  |  |  | (36) |
Net income available for common stock |  |  |  |  |  |  | 350 |
Total assets | 8,602 |  |  | 819 |  |  | 575 |  |  | 9,996 |
Construction and acquisition expenditures | 342 |  |  | 42 |  |  | — |  |  | 384 |
WPL - WPL is a utility serving customers in Wisconsin and includes three reportable segments: a) electric operations; b) gas operations; and c) other, which includes the unallocated portions of the utility business. Various line items in the following tables are not allocated to the electric and gas segments for management reporting purposes, and therefore, are included only in “Total.” Intersegment revenues were not material to WPL’s operations and there was no single customer whose revenues were 10% or more of WPL’s consolidated revenues. All of WPL’s operations and assets are located in the U.S. Certain financial information relating to WPL’s business segments, which represent the services provided to its customers, was as follows (in millions):
2023 | Electric |  | Gas |  | Other |  | Total
Revenues | $1,584 |  |  | $240 |  |  | $3 |  |  | $1,827 |
Depreciation and amortization | 254 |  |  | 26 |  |  | — |  |  | 280 |
Operating income | 437 |  |  | 35 |  |  | — |  |  | 472 |
Interest expense |  |  |  |  |  |  | 149 |
Income taxes |  |  |  |  |  |  | 60 |
Net income |  |  |  |  |  |  | 345 |
Total assets | 8,522 |  |  | 763 |  |  | 349 |  |  | 9,634 |
Construction and acquisition expenditures | 970 |  |  | 49 |  |  | — |  |  | 1,019 |
2022 | Electric |  | Gas |  | Other |  | Total
Revenues | $1,562 |  |  | $291 |  |  | $3 |  |  | $1,856 |
Depreciation and amortization | 259 |  |  | 24 |  |  | — |  |  | 283 |
Operating income | 408 |  |  | 44 |  |  | — |  |  | 452 |
Interest expense |  |  |  |  |  |  | 121 |
Income taxes |  |  |  |  |  |  | 66 |
Net income |  |  |  |  |  |  | 315 |
Total assets | 7,885 |  |  | 759 |  |  | 343 |  |  | 8,987 |
Construction and acquisition expenditures | 982 |  |  | 38 |  |  | — |  |  | 1,020 |
2021 | Electric |  | Gas |  | Other |  | Total
Revenues | $1,329 |  |  | $191 |  |  | $3 |  |  | $1,523 |
Depreciation and amortization | 253 |  |  | 23 |  |  | — |  |  | 276 |
Operating income (loss) | 296 |  |  | 20 |  |  | (8) |  |  | 308 |
Interest expense |  |  |  |  |  |  | 105 |
Income tax benefit |  |  |  |  |  |  | (51) |
Net income |  |  |  |  |  |  | 268 |
Total assets | 6,322 |  |  | 668 |  |  | 528 |  |  | 7,518 |
Construction and acquisition expenditures | 638 |  |  | 48 |  |  | — |  |  | 686 |

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