v3.26.1
Reportable Segments (Schedule of Financial Information by Reportable Segments, Consumers) (Details) - USD ($)
$ in Millions
 3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Dec. 31, 2025
Segment Reporting [Line Items]          
Operating Revenue $ 1,829 $ 1,838 $ 4,559 $ 4,285  
Power supply cost 573 603 1,264 1,218  
Operating Income 264 317 754 811  
Total other income 75 137 150 187  
Total interest charges 210 199 413 385  
Income (Loss) Before Income Taxes 129 255 491 613  
Income tax expense 33 62 118 125  
Net Income (Loss) 120 201 460 505  
Other segment items 21 5 82 12  
Net Income (Loss) Available to Common Stockholders 117 198 455 500  
Total assets 40,905 37,699 40,905 37,699 $ 39,941
Consumers Energy Company          
Segment Reporting [Line Items]          
Operating Revenue 1,726 1,746 4,338 4,094  
Power supply cost 517 537 1,117 1,083  
Cost of gas sold 102 123 616 505  
Maintenance and other operating expenses 429 376 845 749  
Depreciation and amortization 293 276 693 651  
General taxes 114 106 284 265  
Total operating expenses 1,455 1,418 3,555 3,253  
Operating Income 271 328 783 841  
Total other income 69 60 135 106  
Total interest charges 144 141 283 271  
Income (Loss) Before Income Taxes 196 247 635 676  
Income tax expense 38 59 131 142  
Net Income (Loss) 158 188 504 534  
Other segment items (1) (1) (1) (1)  
Net Income (Loss) Available to Common Stockholders 157 187 503 533  
Property, plant, and equipment, gross 37,175 34,406 37,175 34,406 36,120
Total assets 38,266 35,467 38,266 35,467 $ 37,091
Operating Segments          
Segment Reporting [Line Items]          
Operating Revenue 1,829 1,838 4,559 4,285  
Power supply cost 573 603 1,264 1,218  
Operating Income 270 320 762 816  
Total other income 72 61 145 108  
Total interest charges 148 139 289 269  
Income (Loss) Before Income Taxes 194 242 618 655  
Income tax expense 36 36 152 139  
Other segment items 24 8 87 17  
Net Income (Loss) Available to Common Stockholders 182 214 553 533  
Total assets 40,808 37,435 40,808 37,435  
Operating Segments | Consumers Energy Company          
Segment Reporting [Line Items]          
Operating Revenue 1,726 1,746 4,338 4,094  
Power supply cost 517 537 1,117 1,083  
Cost of gas sold 102 123 616 505  
Maintenance and other operating expenses 429 376 845 749  
Depreciation and amortization 293 276 693 651  
General taxes 114 106 284 265  
Total operating expenses 1,455 1,418 3,555 3,253  
Operating Income 271 328 783 841  
Total other income 69 59 135 105  
Total interest charges 144 140 283 270  
Income (Loss) Before Income Taxes 196 247 635 676  
Income tax expense 31 54 140 146  
Net Income (Loss) 165 193 495 530  
Other segment items (1) (1) (1) (1)  
Net Income (Loss) Available to Common Stockholders 164 192 494 529  
Property, plant, and equipment, gross 37,143 34,370 37,143 34,370  
Total assets 38,213 35,427 38,213 35,427  
Operating Segments | Electric Utility          
Segment Reporting [Line Items]          
Operating Revenue 1,338 1,359 2,706 2,658  
Power supply cost 517 537 1,117 1,083  
Operating Income 199 263 378 465  
Total other income 46 36 89 63  
Total interest charges 86 89 169 171  
Income (Loss) Before Income Taxes 159 210 298 357  
Income tax expense 21 42 50 65  
Other segment items (1) (1) (1) (1)  
Net Income (Loss) Available to Common Stockholders 137 167 247 291  
Total assets 23,926 21,942 23,926 21,942  
Operating Segments | Electric Utility | Consumers Energy Company          
Segment Reporting [Line Items]          
Operating Revenue 1,338 1,359 2,706 2,658  
Power supply cost 517 537 1,117 1,083  
Cost of gas sold 0 0 0 0  
Maintenance and other operating expenses 308 264 585 521  
Depreciation and amortization 236 222 469 443  
General taxes 78 73 157 146  
Total operating expenses 1,139 1,096 2,328 2,193  
Operating Income 199 263 378 465  
Total other income 46 36 89 63  
Total interest charges 86 89 169 171  
Income (Loss) Before Income Taxes 159 210 298 357  
Income tax expense 21 42 50 65  
Net Income (Loss) 138 168 248 292  
Other segment items (1) (1) (1) (1)  
Net Income (Loss) Available to Common Stockholders 137 167 247 291  
Property, plant, and equipment, gross 22,595 20,761 22,595 20,761  
Total assets 23,979 21,997 23,979 21,997  
Operating Segments | Gas Utility          
Segment Reporting [Line Items]          
Operating Revenue 388 387 1,632 1,436  
Power supply cost 0 0 0 0  
Operating Income 72 65 405 376  
Total other income 23 23 46 42  
Total interest charges 58 51 114 99  
Income (Loss) Before Income Taxes 37 37 337 319  
Income tax expense 10 12 90 81  
Other segment items 0 0 0 0  
Net Income (Loss) Available to Common Stockholders 27 25 247 238  
Total assets 14,193 13,388 14,193 13,388  
Operating Segments | Gas Utility | Consumers Energy Company          
Segment Reporting [Line Items]          
Operating Revenue 388 387 1,632 1,436  
Power supply cost 0 0 0 0  
Cost of gas sold 102 123 616 505  
Maintenance and other operating expenses 121 112 260 228  
Depreciation and amortization 57 54 224 208  
General taxes 36 33 127 119  
Total operating expenses 316 322 1,227 1,060  
Operating Income 72 65 405 376  
Total other income 23 23 46 42  
Total interest charges 58 51 114 99  
Income (Loss) Before Income Taxes 37 37 337 319  
Income tax expense 10 12 90 81  
Net Income (Loss) 27 25 247 238  
Other segment items 0 0 0 0  
Net Income (Loss) Available to Common Stockholders 27 25 247 238  
Property, plant, and equipment, gross 14,548 13,609 14,548 13,609  
Total assets 14,234 13,430 14,234 13,430  
Other Reconciling Items          
Segment Reporting [Line Items]          
Operating Revenue 0 0 0 0  
Power supply cost 0 0 0 0  
Operating Income (6) (3) (8) (5)  
Total other income 3 76 5 79  
Total interest charges 62 60 124 116  
Income (Loss) Before Income Taxes (65) 13 (127) (42)  
Income tax expense (3) 26 (34) (14)  
Other segment items (3) (3) (5) (5)  
Net Income (Loss) Available to Common Stockholders (65) (16) (98) (33)  
Total assets 97 264 97 264  
Other Reconciling Items | Consumers Energy Company          
Segment Reporting [Line Items]          
Operating Revenue 0 0 0 0  
Power supply cost 0 0 0 0  
Cost of gas sold 0 0 0 0  
Maintenance and other operating expenses 0 0 0 0  
Depreciation and amortization 0 0 0 0  
General taxes 0 0 0 0  
Total operating expenses 0 0 0 0  
Operating Income 0 0 0 0  
Total other income 0 1 0 1  
Total interest charges 0 1 0 1  
Income (Loss) Before Income Taxes 0 0 0 0  
Income tax expense 7 5 (9) (4)  
Net Income (Loss) (7) (5) 9 4  
Other segment items 0 0 0 0  
Net Income (Loss) Available to Common Stockholders (7) (5) 9 4  
Property, plant, and equipment, gross 32 36 32 36  
Total assets $ 53 $ 40 $ 53 $ 40