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Segments Of Business (Schedule Of Segment Of Business) (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
Segment Reporting Information [Line Items] |  |  |
Revenues | $ 3,416 | $ 3,648 | $ 3,534
Depreciation and amortization | 615 | 567 | 507
Operating income (loss) | 740 | 778 | 694
Interest expense | 275 | 273 | 247
Equity income from unconsolidated investments, net | (61) | (53) | (55)
Income tax expense (benefit) | (57) | 69 | 48
Net income attributable to common shareowners | 614 | 557 | 512
Total assets | 17,710 | 16,701 | 15,426
Investments in equity method subsidiaries | 476 | 458 | 421
Construction and acquisition expenditures | 1,366 | 1,640 | 1,634
IPL [Member] |  |  |
Segment Reporting Information [Line Items] |  |  |
Revenues | 1,947 | 2,089 | 2,042
Operating income (loss) | 410 | 403 | 351
Interest expense | 139 | 127 | 119
Income tax expense (benefit) | (47) | 24 | (3)
Net income attributable to common shareowners | 324 | 284 | 264
Total assets | 9,849 | 9,277 |
WPL [Member] |  |  |
Segment Reporting Information [Line Items] |  |  |
Revenues | 1,395 | 1,476 | 1,453
Operating income (loss) | 306 | 347 | 313
Interest expense | 104 | 102 | 98
Income tax expense (benefit) | (19) | 49 | 36
Total assets | 6,912 | 6,507 |
Electric [Member] |  |  |
Segment Reporting Information [Line Items] |  |  |
Revenues | 2,920 | 3,064 | 3,000
Depreciation and amortization | 556 | 513 | 457
Operating income (loss) | 643 | 679 | 610
Equity income from unconsolidated investments, net | (2) | (1) | (1)
Total assets | 14,358 | 13,659 | 12,486
Investments in equity method subsidiaries | 11 | 9 | 8
Construction and acquisition expenditures | 1,109 | 1,439 | 1,422
Electric [Member] | IPL [Member] |  |  |
Segment Reporting Information [Line Items] |  |  |
Revenues | 1,695 | 1,781 | 1,731
Depreciation and amortization | 321 | 295 | 255
Operating income (loss) | 358 | 360 | 318
Total assets | 8,518 | 8,075 | 7,220
Construction and acquisition expenditures | 626 | 964 | 891
Electric [Member] | WPL [Member] |  |  |
Segment Reporting Information [Line Items] |  |  |
Revenues | 1,225 | 1,283 | 1,269
Depreciation and amortization | 235 | 218 | 202
Operating income (loss) | 285 | 319 | 292
Total assets | 5,840 | 5,584 | 5,266
Construction and acquisition expenditures | 483 | 475 | 531
Gas [Member] |  |  |
Segment Reporting Information [Line Items] |  |  |
Revenues | 373 | 455 | 447
Depreciation and amortization | 49 | 47 | 42
Operating income (loss) | 74 | 70 | 53
Equity income from unconsolidated investments, net | 0 | 0 | 0
Total assets | 1,413 | 1,269 | 1,184
Investments in equity method subsidiaries | 0 | 0 | 0
Construction and acquisition expenditures | 182 | 100 | 147
Gas [Member] | IPL [Member] |  |  |
Segment Reporting Information [Line Items] |  |  |
Revenues | 208 | 264 | 266
Depreciation and amortization | 30 | 29 | 25
Operating income (loss) | 50 | 39 | 28
Total assets | 766 | 734 | 687
Construction and acquisition expenditures | 59 | 56 | 100
Gas [Member] | WPL [Member] |  |  |
Segment Reporting Information [Line Items] |  |  |
Revenues | 165 | 191 | 181
Depreciation and amortization | 19 | 18 | 17
Operating income (loss) | 24 | 31 | 25
Total assets | 647 | 535 | 497
Construction and acquisition expenditures | 123 | 44 | 47
Other Utility [Member] |  |  |
Segment Reporting Information [Line Items] |  |  |
Revenues | 49 | 46 | 48
Depreciation and amortization | 5 | 3 | 3
Operating income (loss) | (1) | 1 | 1
Equity income from unconsolidated investments, net | 0 | 0 | 0
Total assets | 990 | 856 | 893
Investments in equity method subsidiaries | 0 | 0 | 0
Construction and acquisition expenditures | 2 | 0 | 0
Other Utility [Member] | IPL [Member] |  |  |
Segment Reporting Information [Line Items] |  |  |
Revenues | 44 | 44 | 45
Depreciation and amortization | 5 | 3 | 3
Operating income (loss) | 2 | 4 | 5
Total assets | 565 | 468 | 504
Construction and acquisition expenditures | 2 | 0 | 0
Other Utility [Member] | WPL [Member] |  |  |
Segment Reporting Information [Line Items] |  |  |
Revenues | 5 | 2 | 3
Depreciation and amortization | 0 | 0 | 0
Operating income (loss) | (3) | (3) | (4)
Total assets | 425 | 388 | 389
Construction and acquisition expenditures | 0 | 0 | 0
Utility Business [Member] |  |  |
Segment Reporting Information [Line Items] |  |  |
Revenues | 3,342 | 3,565 | 3,495
Depreciation and amortization | 610 | 563 | 502
Operating income (loss) | 716 | 750 | 664
Interest expense | 243 | 229 | 217
Equity income from unconsolidated investments, net | (2) | (1) | (1)
Income tax expense (benefit) | (66) | 73 | 33
Net income attributable to common shareowners | 573 | 517 | 472
Total assets | 16,761 | 15,784 | 14,563
Investments in equity method subsidiaries | 11 | 9 | 8
Construction and acquisition expenditures | 1,293 | 1,539 | 1,569
Utility Business [Member] | IPL [Member] |  |  |
Segment Reporting Information [Line Items] |  |  |
Revenues | 1,947 | 2,089 | 2,042
Depreciation and amortization | 356 | 327 | 283
Operating income (loss) | 410 | 403 | 351
Interest expense | 139 | 127 | 119
Income tax expense (benefit) | (47) | 24 | (3)
Net income attributable to common shareowners | 324 | 284 | 264
Total assets | 9,849 | 9,277 | 8,411
Construction and acquisition expenditures | 687 | 1,020 | 991
Utility Business [Member] | WPL [Member] |  |  |
Segment Reporting Information [Line Items] |  |  |
Revenues | 1,395 | 1,476 | 1,453
Depreciation and amortization | 254 | 236 | 219
Operating income (loss) | 306 | 347 | 313
Interest expense | 104 | 102 | 98
Income tax expense (benefit) | (19) | 49 | 36
Net income attributable to common shareowners | 249 | 233 | 208
Total assets | 6,912 | 6,507 | 6,152
Construction and acquisition expenditures | 606 | 519 | 578
Non-Utility [Member] |  |  |
Segment Reporting Information [Line Items] |  |  |
Revenues | 74 | 83 | 39
Depreciation and amortization | 5 | 4 | 5
Operating income (loss) | 24 | 28 | 30
Interest expense | 32 | 44 | 30
Equity income from unconsolidated investments, net | (59) | (52) | (54)
Income tax expense (benefit) | 9 | (4) | 15
Net income attributable to common shareowners | 41 | 40 | 40
Total assets | 949 | 917 | 863
Investments in equity method subsidiaries | 465 | 449 | 413
Construction and acquisition expenditures | $ 73 | $ 101 | $ 65

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