v3.26.3
Reportable Segments (Schedule of Financial Information by Reportable Segments, CMS Energy, including 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  
Maintenance and other operating expenses 920 416 1,832 1,218  
Depreciation and amortization 298 288 1,018 964  
General taxes 111 107 402 378  
Total operating expenses 2,136 1,540 5,941 5,014  
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  
Income (Loss) From Continuing Operations (91) 272 282 760  
Other segment items 212 3 294 15  
Net Income (Loss) Available to Common Stockholders 121 275 576 775  
Plant, property, and equipment, gross 39,300 36,583 39,300 36,583 $ 37,763
Total assets 41,683 38,008 41,683 38,008 $ 39,941
Cost of gas sold          
Segment Reporting [Line Items]          
Cost of gas sold 45 42 663 549  
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  
Maintenance and other operating expenses 917 413 1,822 1,210  
Depreciation and amortization 298 288 1,018 964  
General taxes 111 107 401 378  
Total operating expenses 2,133 1,537 5,930 5,006  
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  
Income (Loss) From Continuing Operations 5 332 471 848  
Other segment items 214 5 301 22  
Net Income (Loss) Available to Common Stockholders 219 337 772 870  
Plant, property, and equipment, gross 39,274 36,553 39,274 36,553  
Total assets 41,462 37,866 41,462 37,866  
Operating Segments | Cost of gas sold          
Segment Reporting [Line Items]          
Cost of gas sold 45 42 663 549  
Other Reconciling Items          
Segment Reporting [Line Items]          
Operating Revenue 0 0 0 0  
Power supply cost 0 0 0 0  
Maintenance and other operating expenses 3 3 10 8  
Depreciation and amortization 0 0 0 0  
General taxes 0 0 1 0  
Total operating expenses 3 3 11 8  
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)  
Income (Loss) From Continuing Operations (96) (60) (189) (88)  
Other segment items (2) (2) (7) (7)  
Net Income (Loss) Available to Common Stockholders (98) (62) (196) (95)  
Plant, property, and equipment, gross 26 30 26 30  
Total assets 221 142 221 142  
Other Reconciling Items | Cost of gas sold          
Segment Reporting [Line Items]          
Cost of gas sold 0 0 0 0  
Electric Utility | Operating Segments          
Segment Reporting [Line Items]          
Operating Revenue 1,774 1,679 4,480 4,337  
Power supply cost 677 624 1,794 1,707  
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  
Income (Loss) From Continuing Operations 399 326 647 618  
Other segment items 0 0 (1) (1)  
Net Income (Loss) Available to Common Stockholders 399 326 646 617  
Plant, property, and equipment, gross 23,383 21,095 23,383 21,095  
Total assets 24,309 21,917 24,309 21,917  
Electric Utility | Operating Segments | Cost of gas sold          
Segment Reporting [Line Items]          
Cost of gas sold 0 0 0 0  
Gas Utility | Operating Segments          
Segment Reporting [Line Items]          
Operating Revenue 264 234 1,896 1,670  
Power supply cost 0 0 0 0  
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  
Income (Loss) From Continuing Operations 13 0 260 238  
Other segment items 0 0 0 0  
Net Income (Loss) Available to Common Stockholders 13 0 260 238  
Plant, property, and equipment, gross 14,975 13,890 14,975 13,890  
Total assets 14,738 13,720 14,738 13,720  
Gas Utility | Operating Segments | Cost of gas sold          
Segment Reporting [Line Items]          
Cost of gas sold 43 40 659 545  
NorthStar Clean Energy | Operating Segments          
Segment Reporting [Line Items]          
Operating Revenue 145 108 366 299  
Power supply cost 85 63 232 198  
Maintenance and other operating expenses 555 25 615 73  
Depreciation and amortization 10 14 37 39  
General taxes 3 3 9 9  
Total operating expenses 655 107 897 323  
Operating Income (510) 1 (531) (24)  
Other income (expense) (19) 4 (9) 7  
Total interest charges 2 (1) 8 (2)  
Income (Loss) Before Income Taxes (531) 6 (548) (15)  
Income tax expense (benefit) (124) 0 (112) (7)  
Income (Loss) From Continuing Operations (407) 6 (436) (8)  
Other segment items 214 5 302 23  
Net Income (Loss) Available to Common Stockholders (193) 11 (134) 15  
Plant, property, and equipment, gross 916 1,568 916 1,568  
Total assets 2,415 2,229 2,415 2,229  
NorthStar Clean Energy | Operating Segments | Cost of gas sold          
Segment Reporting [Line Items]          
Cost of gas sold $ 2 $ 2 $ 4 $ 4