v3.25.2
Segments Of Business (Schedule Of Segments Of Business) (Details) - USD ($)
$ in Millions
 3 Months Ended 6 Months Ended
Jun. 30, 2025
Jun. 30, 2024
Jun. 30, 2025
Jun. 30, 2024
Dec. 31, 2024
Segment Reporting Information [Line Items]          
Electric utility revenues $ 851 $ 789 $ 1,703 $ 1,580  
Gas utility revenues 76 69 316 273  
Other revenues 34 36 69 72  
Total revenues 961 894 2,088 1,925  
Electric production fuel and purchased power 150 138 325 301  
Electric transmission service 151 147 308 300  
Cost of gas sold 30 25 167 139  
Asset valuation charge for IPL's Lansing Generating Station 0 60 0 60  
Other operation and maintenance 168 177 327 336  
Depreciation and amortization 208 188 420 376  
Interest expense 124 108 243 215  
Equity income from unconsolidated investments, net (10) (15) (23) (31)  
Income tax expense (benefit) (43) (33) (91) (43)  
Other 9 12 25 27  
Net income (loss) 174 87 387 245  
Total assets 23,750 21,836 23,750 21,836 $ 22,714
Investments in equity method subsidiaries 645 606 645 606  
Construction and acquisition expenditures 483 450 1,065 960  
IPL [Member]          
Segment Reporting Information [Line Items]          
Electric utility revenues 418 404 848 795  
Gas utility revenues 40 40 158 148  
Total revenues 469 453 1,030 966  
Electric production fuel and purchased power 40 48 107 116  
Electric transmission service 100 99 207 202  
Cost of gas sold 17 17 81 77  
Asset valuation charge for IPL's Lansing Generating Station 0 60 0 60  
Depreciation and amortization 115 97 230 193  
Income tax expense (benefit) (37) (33) (77) (43)  
Net income (loss) 98 18 209 81  
Total assets 12,180   12,180   11,407
WPL [Member]          
Segment Reporting Information [Line Items]          
Electric utility revenues 433 385 855 785  
Gas utility revenues 36 29 158 125  
Total revenues 469 415 1,014 911  
Electric production fuel and purchased power 110 90 218 186  
Electric transmission service 51 49 101 98  
Cost of gas sold 13 8 86 62  
Depreciation and amortization 90 87 183 178  
Income tax expense (benefit) (5) 3 (10) 8  
Net income (loss) 87 64 198 156  
Total assets 10,236   10,236   $ 10,106
Total Reportable Segments [Member]          
Segment Reporting Information [Line Items]          
Electric utility revenues 851 789 1,703 1,580  
Gas utility revenues 76 69 316 273  
Other revenues 11 10 25 24  
Total revenues 938 868 2,044 1,877  
Electric production fuel and purchased power 150 138 325 302  
Electric transmission service 151 148 308 300  
Cost of gas sold 30 25 167 139  
Asset valuation charge for IPL's Lansing Generating Station   60   60  
Other operation and maintenance 156 169 306 315  
Depreciation and amortization 205 184 413 371  
Interest expense 95 83 185 166  
Equity income from unconsolidated investments, net (1) (1) (1) (1)  
Income tax expense (benefit) (42) (30) (87) (35)  
Other 9 10 21 23  
Net income (loss) 185 82 407 237  
Total assets 22,416 20,657 22,416 20,657  
Investments in equity method subsidiaries 23 22 23 22  
Construction and acquisition expenditures 422 392 976 870  
IPL [Member]          
Segment Reporting Information [Line Items]          
Electric utility revenues 418 404 848 795  
Gas utility revenues 40 40 158 148  
Other revenues 11 9 24 23  
Total revenues 469 453 1,030 966  
Electric production fuel and purchased power 40 48 107 116  
Electric transmission service 100 99 207 202  
Cost of gas sold 17 17 81 77  
Asset valuation charge for IPL's Lansing Generating Station   60   60  
Other operation and maintenance 84 102 169 187  
Depreciation and amortization 115 97 230 193  
Interest expense 52 42 99 84  
Equity income from unconsolidated investments, net 0 0 0 0  
Income tax expense (benefit) (37) (33) (77) (43)  
Other 0 3 5 9  
Net income (loss) 98 18 209 81  
Total assets 12,180 10,732 12,180 10,732  
Investments in equity method subsidiaries 5 5 5 5  
Construction and acquisition expenditures 252 247 628 500  
WPL [Member]          
Segment Reporting Information [Line Items]          
Electric utility revenues 433 385 855 785  
Gas utility revenues 36 29 158 125  
Other revenues 0 1 1 1  
Total revenues 469 415 1,014 911  
Electric production fuel and purchased power 110 90 218 186  
Electric transmission service 51 49 101 98  
Cost of gas sold 13 8 86 62  
Other operation and maintenance 72 67 137 128  
Depreciation and amortization 90 87 183 178  
Interest expense 43 41 86 82  
Equity income from unconsolidated investments, net (1) (1) (1) (1)  
Income tax expense (benefit) (5) 3 (10) 8  
Other 9 7 16 14  
Net income (loss) 87 64 198 156  
Total assets 10,236 9,925 10,236 9,925  
Investments in equity method subsidiaries 18 17 18 17  
Construction and acquisition expenditures 170 145 348 370  
Other [Member]          
Segment Reporting Information [Line Items]          
Other revenues 23 26 44 48  
Total revenues 23 26 44 48  
Other operation and maintenance 12 8 21 21  
Depreciation and amortization 3 4 7 5  
Interest expense 29 25 58 49  
Equity income from unconsolidated investments, net (9) (14) (22) (30)  
Income tax expense (benefit) (1) (3) (4) (8)  
Other 0 1 4 3  
Net income (loss) (11) 5 (20) 8  
Total assets 1,334 1,179 1,334 1,179  
Investments in equity method subsidiaries 622 584 622 584  
Construction and acquisition expenditures $ 61 $ 58 $ 89 $ 90