v3.25.4
Financings and Capitalization (Summary of Long-Term Debt) (Details) - USD ($)
$ / shares in Units, $ in Millions
 12 Months Ended
Jun. 01, 2035
Dec. 01, 2030
Jun. 01, 2030
Dec. 31, 2025
Dec. 31, 2024
Debt Instrument [Line Items]          
Total principal amount outstanding       $ 18,939 $ 16,545
Current amounts       (950) (1,192)
Long-term debt – related parties principal amount outstanding       (3,458)  
Unamortized discounts       (28) (29)
Unamortized issuance costs       (154) (130)
Long-term debt       17,807 15,194
Consumers Energy Company          
Debt Instrument [Line Items]          
Total principal amount outstanding       13,215 12,205
Current amounts       (573) (452)
Long-term debt – related parties principal amount outstanding       (1,125)  
Unamortized discounts       (26) (27)
Unamortized issuance costs       (73) (73)
Consumers Energy Company | Related Party          
Debt Instrument [Line Items]          
Long-term debt – related parties principal amount outstanding       (1,019) (835)
Long-term debt       1,005 823
Consumers Energy Company | Nonrelated Party          
Debt Instrument [Line Items]          
Long-term debt       11,524 10,818
First mortgage bonds | Consumers Energy Company          
Debt Instrument [Line Items]          
Total principal amount outstanding       12,520 11,395
First mortgage bonds | Consumers Energy Company | Related Party          
Debt Instrument [Line Items]          
Unamortized discounts       (5) (5)
Unamortized issuance costs       (9) (7)
Tax-exempt revenue bonds | Consumers Energy Company          
Debt Instrument [Line Items]          
Total principal amount outstanding       110 110
Securitization bonds | Consumers Energy Company          
Debt Instrument [Line Items]          
Total principal amount outstanding       $ 585 700
5.240 First Mortgage Bonds Due 2026 | First mortgage bonds | Consumers Energy Company          
Debt Instrument [Line Items]          
Interest Rate (%)       5.24%  
Total principal amount outstanding       $ 115 115
3.680% First Mortgage Bonds Due 2027 | First mortgage bonds | Consumers Energy Company          
Debt Instrument [Line Items]          
Interest Rate (%)       3.68%  
Total principal amount outstanding       $ 100 100
3.390 % First Mortgage Bonds Due 2027 | First mortgage bonds | Consumers Energy Company          
Debt Instrument [Line Items]          
Interest Rate (%)       3.39%  
Total principal amount outstanding       $ 35 35
4.650% First Mortgage Bonds Due 2028 | First mortgage bonds | Consumers Energy Company          
Debt Instrument [Line Items]          
Interest Rate (%)       4.65%  
Total principal amount outstanding       $ 425 425
3.800% First Mortgage Bonds Due 2028 | First mortgage bonds | Consumers Energy Company          
Debt Instrument [Line Items]          
Interest Rate (%)       3.80%  
Total principal amount outstanding       $ 300 300
4.900% First Mortgage Bonds Due 2029 | First mortgage bonds | Consumers Energy Company          
Debt Instrument [Line Items]          
Interest Rate (%)       4.90%  
Total principal amount outstanding       $ 500 500
5.070% First Mortgage Bonds Due 2029 | First mortgage bonds | Consumers Energy Company          
Debt Instrument [Line Items]          
Interest Rate (%)       5.07%  
Total principal amount outstanding       $ 50 50
4.600% First Mortgage Bonds Due 2029 | First mortgage bonds | Consumers Energy Company          
Debt Instrument [Line Items]          
Interest Rate (%)       4.60%  
Total principal amount outstanding       $ 600 600
4.700% First Mortgage Bonds Due 2030 | First mortgage bonds | Consumers Energy Company          
Debt Instrument [Line Items]          
Interest Rate (%)       4.70%  
Total principal amount outstanding       $ 700 700
4.500% First Mortgage Bonds Due 2031 | First mortgage bonds | Consumers Energy Company          
Debt Instrument [Line Items]          
Interest Rate (%)       4.50%  
Total principal amount outstanding       $ 500 0
5.170% First Mortgage Bonds Due 2032 | First mortgage bonds | Consumers Energy Company          
Debt Instrument [Line Items]          
Interest Rate (%)       5.17%  
Total principal amount outstanding       $ 95 95
3.600% First Mortgage Bonds Due 2032 | First mortgage bonds | Consumers Energy Company          
Debt Instrument [Line Items]          
Interest Rate (%)       3.60%  
Total principal amount outstanding       $ 350 350
3.180% First Mortgage Bonds Due 2032 | First mortgage bonds | Consumers Energy Company          
Debt Instrument [Line Items]          
Interest Rate (%)       3.18%  
Total principal amount outstanding       $ 100 100
4.625% First Mortgage Bonds Due 2033 | First mortgage bonds | Consumers Energy Company          
Debt Instrument [Line Items]          
Interest Rate (%)       4.625%  
Total principal amount outstanding       $ 700 700
5.050% First Mortgage Bonds Due 2035 | First mortgage bonds | Consumers Energy Company          
Debt Instrument [Line Items]          
Interest Rate (%)       5.05%  
Total principal amount outstanding       $ 625 0
5.800 % First Mortgage Bonds Due 2035 | First mortgage bonds | Consumers Energy Company          
Debt Instrument [Line Items]          
Interest Rate (%)       5.80%  
Total principal amount outstanding       $ 175 175
5.380% First Mortgage Bonds Due 2037 | First mortgage bonds | Consumers Energy Company          
Debt Instrument [Line Items]          
Interest Rate (%)       5.38%  
Total principal amount outstanding       $ 140 140
3.520% First Mortgage Bonds Due 2037 | First mortgage bonds | Consumers Energy Company          
Debt Instrument [Line Items]          
Interest Rate (%)       3.52%  
Total principal amount outstanding       $ 335 335
4.010% First Mortgage Bonds Due 2038 | First mortgage bonds | Consumers Energy Company          
Debt Instrument [Line Items]          
Interest Rate (%)       4.01%  
Total principal amount outstanding       $ 215 215
6.170% First Mortgage Bonds Due 2040 | First mortgage bonds | Consumers Energy Company          
Debt Instrument [Line Items]          
Interest Rate (%)       6.17%  
Total principal amount outstanding       $ 50 50
4.970% First Mortgage Bonds Due 2040 | First mortgage bonds | Consumers Energy Company          
Debt Instrument [Line Items]          
Interest Rate (%)       4.97%  
Total principal amount outstanding       $ 50 50
4.310% First Mortgage Bonds Due 2042 | First mortgage bonds | Consumers Energy Company          
Debt Instrument [Line Items]          
Interest Rate (%)       4.31%  
Total principal amount outstanding       $ 263 263
3.950% First Mortgage Bonds Due 2043 | First mortgage bonds | Consumers Energy Company          
Debt Instrument [Line Items]          
Interest Rate (%)       3.95%  
Total principal amount outstanding       $ 425 425
4.100% First Mortgage Bonds Due 2045 | First mortgage bonds | Consumers Energy Company          
Debt Instrument [Line Items]          
Interest Rate (%)       4.10%  
Total principal amount outstanding       $ 250 250
3.250% First Mortgage Bonds Due 2046 | First mortgage bonds | Consumers Energy Company          
Debt Instrument [Line Items]          
Interest Rate (%)       3.25%  
Total principal amount outstanding       $ 450 450
3.950% First Mortgage Bonds Due 2047 | First mortgage bonds | Consumers Energy Company          
Debt Instrument [Line Items]          
Interest Rate (%)       3.95%  
Total principal amount outstanding       $ 350 350
4.050% First Mortgage Bonds Due 2048 | First mortgage bonds | Consumers Energy Company          
Debt Instrument [Line Items]          
Interest Rate (%)       4.05%  
Total principal amount outstanding       $ 550 550
4.350% First Mortgage Bonds Due 2049 | First mortgage bonds | Consumers Energy Company          
Debt Instrument [Line Items]          
Interest Rate (%)       4.35%  
Total principal amount outstanding       $ 550 550
3.750% First Mortgage Bonds Due 2050 | First mortgage bonds | Consumers Energy Company          
Debt Instrument [Line Items]          
Interest Rate (%)       3.75%  
Total principal amount outstanding       $ 300 300
3.100% First Mortgage Bonds Due 2050 | First mortgage bonds | Consumers Energy Company          
Debt Instrument [Line Items]          
Interest Rate (%)       3.10%  
Total principal amount outstanding       $ 550 550
3.500% First Mortgage Bonds Due 2051 | First mortgage bonds | Consumers Energy Company          
Debt Instrument [Line Items]          
Interest Rate (%)       3.50%  
Total principal amount outstanding       $ 575 575
2.650% First Mortgage Bonds Due 2052 | First mortgage bonds | Consumers Energy Company          
Debt Instrument [Line Items]          
Interest Rate (%)       2.65%  
Total principal amount outstanding       $ 300 300
4.200% First Mortgage Bonds Due 2052 | First mortgage bonds | Consumers Energy Company          
Debt Instrument [Line Items]          
Interest Rate (%)       4.20%  
Total principal amount outstanding       $ 450 450
3.860% First Mortgage Bonds Due 2052 | First mortgage bonds | Consumers Energy Company          
Debt Instrument [Line Items]          
Interest Rate (%)       3.86%  
Total principal amount outstanding       $ 50 50
4.280% First Mortgage Bonds Due 2057 | First mortgage bonds | Consumers Energy Company          
Debt Instrument [Line Items]          
Interest Rate (%)       4.28%  
Total principal amount outstanding       $ 185 185
2.500% First Mortgage Bonds Due 2060 | First mortgage bonds | Consumers Energy Company          
Debt Instrument [Line Items]          
Interest Rate (%)       2.50%  
Total principal amount outstanding       $ 525 525
4.350% First Mortgage Bonds Due 2064 | First mortgage bonds | Consumers Energy Company          
Debt Instrument [Line Items]          
Interest Rate (%)       4.35%  
Total principal amount outstanding       $ 250 250
Variable Rate First Mortgage Bonds Due 2069 | First mortgage bonds | Consumers Energy Company          
Debt Instrument [Line Items]          
Total principal amount outstanding       $ 76 $ 76
Interest rate at period end       3.685% 4.32%
Variable Rate First Mortgage Bonds Due 2070 | First mortgage bonds | Consumers Energy Company          
Debt Instrument [Line Items]          
Total principal amount outstanding       $ 134 $ 134
Interest rate at period end       3.851% 4.483%
Variable Rate First Mortgage Bonds Due 2070 | First mortgage bonds | Consumers Energy Company          
Debt Instrument [Line Items]          
Total principal amount outstanding       $ 127 $ 127
Interest rate at period end       3.897% 4.551%
0.875% Tax Exempt Revenue Bonds Due 2035 | Tax-exempt revenue bonds | Consumers Energy Company          
Debt Instrument [Line Items]          
Interest Rate (%)       0.875%  
Total principal amount outstanding       $ 35 $ 35
3.350% Tax Exempt Revenue Bonds Due 2049 | Tax-exempt revenue bonds | Consumers Energy Company          
Debt Instrument [Line Items]          
Interest Rate (%)       3.35%  
Total principal amount outstanding       $ 75 75
3.528% Securitization Bonds | Securitization bonds | Consumers Energy Company          
Debt Instrument [Line Items]          
Total principal amount outstanding       $ 81 $ 112
Weighted average interest rate       3.528% 3.528%
5.322% Securitization Bonds | Securitization bonds | Consumers Energy Company          
Debt Instrument [Line Items]          
Total principal amount outstanding       $ 504 $ 588
Weighted average interest rate       5.281% 5.322%
Variable Rate First Mortgage Bonds | First mortgage bonds | Consumers Energy Company | SOFR          
Debt Instrument [Line Items]          
Basis spread on variable rate       0.038%  
CMS Energy          
Debt Instrument [Line Items]          
Total principal amount outstanding       $ 6,285 $ 5,025
Current amounts       (300) (740)
Long-term debt – related parties principal amount outstanding       (2,110)  
Long-term debt       5,906 4,226
CMS Energy | Consumers Energy Company          
Debt Instrument [Line Items]          
Total principal amount outstanding       12,196 11,370
CMS Energy | Senior notes          
Debt Instrument [Line Items]          
Total principal amount outstanding       1,475 1,725
CMS Energy | Convertible debt          
Debt Instrument [Line Items]          
Total principal amount outstanding       1,800 800
CMS Energy | Junior subordinated notes          
Debt Instrument [Line Items]          
Total principal amount outstanding       3,010 2,010
CMS Energy | Term loan facility          
Debt Instrument [Line Items]          
Total principal amount outstanding       $ 0 490
CMS Energy | 3.600% Senior Notes Due 2025 | Senior notes          
Debt Instrument [Line Items]          
Interest Rate (%)       3.60%  
Total principal amount outstanding       $ 0 250
CMS Energy | 3.000% Senior Notes Due 2026 | Senior notes          
Debt Instrument [Line Items]          
Interest Rate (%)       3.00%  
Total principal amount outstanding       $ 300 300
CMS Energy | 2.950% Senior Notes Due 2027 | Senior notes          
Debt Instrument [Line Items]          
Interest Rate (%)       2.95%  
Total principal amount outstanding       $ 275 275
CMS Energy | 3.450% Senior Notes Due 2027 | Senior notes          
Debt Instrument [Line Items]          
Interest Rate (%)       3.45%  
Total principal amount outstanding       $ 350 350
CMS Energy | 4.700% Senior Notes Due 2043 | Senior notes          
Debt Instrument [Line Items]          
Interest Rate (%)       4.70%  
Total principal amount outstanding       $ 250 250
CMS Energy | 4.875% Senior Notes Due 2044 | Senior notes          
Debt Instrument [Line Items]          
Interest Rate (%)       4.875%  
Total principal amount outstanding       $ 300 300
CMS Energy | 3.375% Convertible Senior Notes Due 2028 | Convertible debt          
Debt Instrument [Line Items]          
Interest Rate (%)       3.375%  
Total principal amount outstanding       $ 800 800
CMS Energy | 3.125% Convertible Senior Notes Due 2031 | Convertible debt          
Debt Instrument [Line Items]          
Interest Rate (%)       3.125%  
Total principal amount outstanding       $ 1,000 0
Conversion price (in dollars per share)       $ 90.61  
Unamortized issuance costs       $ 12  
CMS Energy | 4.750% Junior Subordinated Notes Due 2050 | Junior subordinated notes          
Debt Instrument [Line Items]          
Interest Rate (%)       4.75%  
Total principal amount outstanding       $ 500 500
CMS Energy | 4.750% Junior Subordinated Notes Due 2050 | Junior subordinated notes | Forecast | US Treasury (UST) Interest Rate          
Debt Instrument [Line Items]          
Basis spread on variable rate     4.116%    
CMS Energy | 3.750% Junior Subordinated Notes Due 2050 | Junior subordinated notes          
Debt Instrument [Line Items]          
Interest Rate (%)       3.75%  
Total principal amount outstanding       $ 400 400
CMS Energy | 3.750% Junior Subordinated Notes Due 2050 | Junior subordinated notes | Forecast | US Treasury (UST) Interest Rate          
Debt Instrument [Line Items]          
Basis spread on variable rate   2.90%      
CMS Energy | 6.500% Junior Subordinated Notes Due 2055 | Junior subordinated notes          
Debt Instrument [Line Items]          
Interest Rate (%)       6.50%  
Total principal amount outstanding       $ 1,000 0
CMS Energy | 6.500% Junior Subordinated Notes Due 2055 | Junior subordinated notes | Forecast | US Treasury (UST) Interest Rate          
Debt Instrument [Line Items]          
Basis spread on variable rate 1.961%        
CMS Energy | 5.625% Junior Subordinated Notes Due 2078 | Junior subordinated notes          
Debt Instrument [Line Items]          
Interest Rate (%)       5.625%  
Total principal amount outstanding       $ 200 200
CMS Energy | 5.875% Junior Subordinated Notes Due 2078 | Junior subordinated notes          
Debt Instrument [Line Items]          
Interest Rate (%)       5.875%  
Total principal amount outstanding       $ 280 280
CMS Energy | 5.875% Junior Subordinated Notes Due 2079 | Junior subordinated notes          
Debt Instrument [Line Items]          
Interest Rate (%)       5.875%  
Total principal amount outstanding       $ 630 630
CMS Energy | Term Loan Facility Due December 2025 | Term loan facility          
Debt Instrument [Line Items]          
Total principal amount outstanding       0 90
Long-term debt – related parties principal amount outstanding       (110)  
CMS Energy | 5.028% Delayed Draw Unsecured Term Loan Credit Facility Due 2025 | Term loan facility          
Debt Instrument [Line Items]          
Total principal amount outstanding       $ 0 400
CMS Energy | 3.375% Convertible Senior Notes Due 2028 | Convertible debt          
Debt Instrument [Line Items]          
Conversion price (in dollars per share)       $ 73.61  
Unamortized issuance costs       $ 6 9
NorthStar Clean Energy, Including Subsidiaries          
Debt Instrument [Line Items]          
Long-term debt – related parties principal amount outstanding       $ (223)  
NorthStar Clean Energy, Including Subsidiaries | Construction financing agreement | Construction Financing Agreement          
Debt Instrument [Line Items]          
Basis spread on variable rate       2.25%  
Weighted average interest rate       6.476%  
NorthStar Clean Energy, Including Subsidiaries | Revolving Credit Facility Due 2028 | Revolving Credit Facility          
Debt Instrument [Line Items]          
Total principal amount outstanding       $ 235 150
Basis spread on variable rate       1.75%  
Interest rate adjustment       0.05%  
Weighted average interest rate       5.436%  
NorthStar Clean Energy, Including Subsidiaries | Construction Financing Agreement | Construction financing agreement          
Debt Instrument [Line Items]          
Total principal amount outstanding       $ 223 $ 0
Long-term debt – related parties principal amount outstanding       $ (223)