v3.26.3
Reportable Segments (Schedule of Financial Information by Reportable Segments, Consumers) (Details) - USD ($)
$ in Millions
 3 Months Ended 9 Months Ended
Sep. 30, 2026
Sep. 30, 2025
Sep. 30, 2026
Sep. 30, 2025
Dec. 31, 2025
Segment Reporting [Line Items]          
Operating Revenue $ 2,183 $ 2,021 $ 6,742 $ 6,306  
Power supply cost 762 687 2,026 1,905  
Operating Income 47 481 801 1,292  
Other income (expense) 54 62 204 249  
Total interest charges 214 203 627 588  
Income (Loss) Before Income Taxes (113) 340 378 953  
Income Tax Expense (Benefit) (22) 68 96 193  
Net Income (Loss) 123 277 583 782  
Other segment items 212 3 294 15  
Net Income (Loss) Available to Common Stockholders 121 275 576 775  
Total assets 41,683 38,008 41,683 38,008 $ 39,941
Consumers Energy Company          
Segment Reporting [Line Items]          
Operating Revenue 2,038 1,913 6,376 6,007  
Power supply cost 677 624 1,794 1,707  
Cost of gas sold 43 40 659 545  
Maintenance and other operating expenses 362 388 1,207 1,137  
Depreciation and amortization 288 274 981 925  
General taxes 108 104 392 369  
Total operating expenses 1,478 1,430 5,033 4,683  
Operating Income 560 483 1,343 1,324  
Other income (expense) 72 55 207 161  
Total interest charges 149 145 432 416  
Income (Loss) Before Income Taxes 483 393 1,118 1,069  
Income Tax Expense (Benefit) 92 79 223 221  
Net Income (Loss) 391 314 895 848  
Other segment items 0 0 (1) (1)  
Net Income (Loss) Available to Common Stockholders 391 314 894 847  
Property, plant, and equipment, gross 38,381 35,021 38,381 35,021 36,120
Total assets 39,204 35,780 39,204 35,780 $ 37,091
Operating Segments          
Segment Reporting [Line Items]          
Operating Revenue 2,183 2,021 6,742 6,306  
Power supply cost 762 687 2,026 1,905  
Operating Income 50 484 812 1,300  
Other income (expense) 53 60 198 168  
Total interest charges 150 144 439 413  
Income (Loss) Before Income Taxes (47) 400 571 1,055  
Income Tax Expense (Benefit) (52) 68 100 207  
Other segment items 214 5 301 22  
Net Income (Loss) Available to Common Stockholders 219 337 772 870  
Total assets 41,462 37,866 41,462 37,866  
Operating Segments | Consumers Energy Company          
Segment Reporting [Line Items]          
Operating Revenue 2,038 1,913 6,376 6,007  
Power supply cost 677 624 1,794 1,707  
Cost of gas sold 43 40 659 545  
Maintenance and other operating expenses 362 388 1,207 1,137  
Depreciation and amortization 288 274 981 925  
General taxes 108 104 392 369  
Total operating expenses 1,478 1,430 5,033 4,683  
Operating Income 560 483 1,343 1,324  
Other income (expense) 72 56 207 161  
Total interest charges 148 145 431 415  
Income (Loss) Before Income Taxes 484 394 1,119 1,070  
Income Tax Expense (Benefit) 72 68 212 214  
Net Income (Loss) 412 326 907 856  
Other segment items 0 0 (1) (1)  
Net Income (Loss) Available to Common Stockholders 412 326 906 855  
Property, plant, and equipment, gross 38,358 34,985 38,358 34,985  
Total assets 39,140 35,734 39,140 35,734  
Operating Segments | Electric Utility          
Segment Reporting [Line Items]          
Operating Revenue 1,774 1,679 4,480 4,337  
Power supply cost 677 624 1,794 1,707  
Operating Income 505 450 883 915  
Other income (expense) 46 34 135 97  
Total interest charges 87 92 256 263  
Income (Loss) Before Income Taxes 464 392 762 749  
Income Tax Expense (Benefit) 65 66 115 131  
Other segment items 0 0 (1) (1)  
Net Income (Loss) Available to Common Stockholders 399 326 646 617  
Total assets 24,309 21,917 24,309 21,917  
Operating Segments | Electric Utility | Consumers Energy Company          
Segment Reporting [Line Items]          
Operating Revenue 1,774 1,679 4,480 4,337  
Power supply cost 677 624 1,794 1,707  
Cost of gas sold 0 0 0 0  
Maintenance and other operating expenses 256 285 841 806  
Depreciation and amortization 251 239 720 682  
General taxes 85 81 242 227  
Total operating expenses 1,269 1,229 3,597 3,422  
Operating Income 505 450 883 915  
Other income (expense) 46 34 135 97  
Total interest charges 87 92 256 263  
Income (Loss) Before Income Taxes 464 392 762 749  
Income Tax Expense (Benefit) 65 66 115 131  
Net Income (Loss) 399 326 647 618  
Other segment items 0 0 (1) (1)  
Net Income (Loss) Available to Common Stockholders 399 326 646 617  
Property, plant, and equipment, gross 23,383 21,095 23,383 21,095  
Total assets 24,362 21,972 24,362 21,972  
Operating Segments | Gas Utility          
Segment Reporting [Line Items]          
Operating Revenue 264 234 1,896 1,670  
Power supply cost 0 0 0 0  
Operating Income 55 33 460 409  
Other income (expense) 26 22 72 64  
Total interest charges 61 53 175 152  
Income (Loss) Before Income Taxes 20 2 357 321  
Income Tax Expense (Benefit) 7 2 97 83  
Other segment items 0 0 0 0  
Net Income (Loss) Available to Common Stockholders 13 0 260 238  
Total assets 14,738 13,720 14,738 13,720  
Operating Segments | Gas Utility | Consumers Energy Company          
Segment Reporting [Line Items]          
Operating Revenue 264 234 1,896 1,670  
Power supply cost 0 0 0 0  
Cost of gas sold 43 40 659 545  
Maintenance and other operating expenses 106 103 366 331  
Depreciation and amortization 37 35 261 243  
General taxes 23 23 150 142  
Total operating expenses 209 201 1,436 1,261  
Operating Income 55 33 460 409  
Other income (expense) 26 22 72 64  
Total interest charges 61 53 175 152  
Income (Loss) Before Income Taxes 20 2 357 321  
Income Tax Expense (Benefit) 7 2 97 83  
Net Income (Loss) 13 0 260 238  
Other segment items 0 0 0 0  
Net Income (Loss) Available to Common Stockholders 13 0 260 238  
Property, plant, and equipment, gross 14,975 13,890 14,975 13,890  
Total assets 14,778 13,762 14,778 13,762  
Other Reconciling Items          
Segment Reporting [Line Items]          
Operating Revenue 0 0 0 0  
Power supply cost 0 0 0 0  
Operating Income (3) (3) (11) (8)  
Other income (expense) 1 2 6 81  
Total interest charges 64 59 188 175  
Income (Loss) Before Income Taxes (66) (60) (193) (102)  
Income Tax Expense (Benefit) 30 0 (4) (14)  
Other segment items (2) (2) (7) (7)  
Net Income (Loss) Available to Common Stockholders (98) (62) (196) (95)  
Total assets 221 142 221 142  
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  
Other income (expense) 0 (1) 0 0  
Total interest charges 1 0 1 1  
Income (Loss) Before Income Taxes (1) (1) (1) (1)  
Income Tax Expense (Benefit) 20 11 11 7  
Net Income (Loss) (21) (12) (12) (8)  
Other segment items 0 0 0 0  
Net Income (Loss) Available to Common Stockholders (21) (12) (12) (8)  
Property, plant, and equipment, gross 23 36 23 36  
Total assets $ 64 $ 46 $ 64 $ 46