v3.26.1
Reportable Segments (Schedule of Financial Information by Reportable Segments, CMS Energy, including 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  
Maintenance and other operating expenses 464 397 912 802  
Depreciation and amortization 308 288 720 676  
General taxes 118 109 291 271  
Total operating expenses 1,565 1,521 3,805 3,474  
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 (benefit) 33 62 118 125  
Income (Loss) From Continuing Operations 96 193 373 488  
Other segment items 21 5 82 12  
Net Income (Loss) Available to Common Stockholders 117 198 455 500  
Plant, property, and equipment, gross 39,227 35,962 39,227 35,962 $ 37,763
Total assets 40,905 37,699 40,905 37,699 $ 39,941
Cost of gas sold          
Segment Reporting [Line Items]          
Cost of gas sold 102 124 618 507  
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  
Maintenance and other operating expenses 459 394 905 797  
Depreciation and amortization 308 288 720 676  
General taxes 117 109 290 271  
Total operating expenses 1,559 1,518 3,797 3,469  
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 (benefit) 36 36 152 139  
Income (Loss) From Continuing Operations 158 206 466 516  
Other segment items 24 8 87 17  
Net Income (Loss) Available to Common Stockholders 182 214 553 533  
Plant, property, and equipment, gross 39,201 35,932 39,201 35,932  
Total assets 40,808 37,435 40,808 37,435  
Operating Segments | Cost of gas sold          
Segment Reporting [Line Items]          
Cost of gas sold 102 124 618 507  
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 5 3 7 5  
Depreciation and amortization 0 0 0 0  
General taxes 1 0 1 0  
Total operating expenses 6 3 8 5  
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 (benefit) (3) 26 (34) (14)  
Income (Loss) From Continuing Operations (62) (13) (93) (28)  
Other segment items (3) (3) (5) (5)  
Net Income (Loss) Available to Common Stockholders (65) (16) (98) (33)  
Plant, property, and equipment, gross 26 30 26 30  
Total assets 97 264 97 264  
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 1,338 1,359 2,706 2,658  
Power supply cost 517 537 1,117 1,083  
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 (benefit) 21 42 50 65  
Income (Loss) From Continuing Operations 138 168 248 292  
Other segment items (1) (1) (1) (1)  
Net Income (Loss) Available to Common Stockholders 137 167 247 291  
Plant, property, and equipment, gross 22,595 20,761 22,595 20,761  
Total assets 23,926 21,942 23,926 21,942  
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 388 387 1,632 1,436  
Power supply cost 0 0 0 0  
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 (benefit) 10 12 90 81  
Income (Loss) From Continuing Operations 27 25 247 238  
Other segment items 0 0 0 0  
Net Income (Loss) Available to Common Stockholders 27 25 247 238  
Plant, property, and equipment, gross 14,548 13,609 14,548 13,609  
Total assets 14,193 13,388 14,193 13,388  
Gas Utility | Operating Segments | Cost of gas sold          
Segment Reporting [Line Items]          
Cost of gas sold 102 123 616 505  
NorthStar Clean Energy | Operating Segments          
Segment Reporting [Line Items]          
Operating Revenue 103 92 221 191  
Power supply cost 56 66 147 135  
Maintenance and other operating expenses 30 18 60 48  
Depreciation and amortization 15 12 27 25  
General taxes 3 3 6 6  
Total operating expenses 104 100 242 216  
Operating Income (1) (8) (21) (25)  
Total other income 3 2 10 3  
Total interest charges 4 (1) 6 (1)  
Income (Loss) Before Income Taxes (2) (5) (17) (21)  
Income tax expense (benefit) 5 (18) 12 (7)  
Income (Loss) From Continuing Operations (7) 13 (29) (14)  
Other segment items 25 9 88 18  
Net Income (Loss) Available to Common Stockholders 18 22 59 4  
Plant, property, and equipment, gross 2,058 1,562 2,058 1,562  
Total assets 2,689 2,105 2,689 2,105  
NorthStar Clean Energy | Operating Segments | Cost of gas sold          
Segment Reporting [Line Items]          
Cost of gas sold $ 0 $ 1 $ 2 $ 2