v3.26.3
Financings and Capitalization (Schedule of Major Long-Term Debt Issuances and Retirements) (Details) - USD ($)
$ in Millions
1 Months Ended 9 Months Ended
Oct. 27, 2026
Sep. 30, 2026
Sep. 30, 2025
Debt Instrument [Line Items]      
Principal Amount   $ 2,151  
Repayments of debt   685  
Payment for purchase of first mortgage bonds   929 $ 884
Subsequent Event      
Debt Instrument [Line Items]      
Repayments of debt $ 55    
Consumers Energy Company      
Debt Instrument [Line Items]      
Principal Amount   $ 1,750  
Debt instrument, interest rate, stated (in percent)   5.24%  
Repayments of debt   $ 115  
Payment for purchase of first mortgage bonds   220 $ 100
5.125% First Mortgage Bonds Due May 2026 | First mortgage bonds | Consumers Energy Company      
Debt Instrument [Line Items]      
Principal Amount   $ 850  
Debt instrument, interest rate, stated (in percent)   5.125%  
4.900% First Mortgage Bonds Due August 2026 | First mortgage bonds | Consumers Energy Company      
Debt Instrument [Line Items]      
Principal Amount   $ 450  
Debt instrument, interest rate, stated (in percent)   4.90%  
6.100% First Mortgage Bonds Due August 2026 | First mortgage bonds | Consumers Energy Company      
Debt Instrument [Line Items]      
Principal Amount   $ 450  
Debt instrument, interest rate, stated (in percent)   6.10%  
NorthStar Clean Energy, Including Subsidiaries      
Debt Instrument [Line Items]      
Debt instrument, increase (decrease), net   $ 401  
Repayments of debt   270  
NorthStar Clean Energy, Including Subsidiaries | Construction financing agreement      
Debt Instrument [Line Items]      
Repayments of debt   270  
Payment for purchase of first mortgage bonds   156  
NorthStar Clean Energy, Including Subsidiaries | Term Loan      
Debt Instrument [Line Items]      
Debt instrument, increase (decrease), net   24  
NorthStar Clean Energy, Including Subsidiaries | Term Loan      
Debt Instrument [Line Items]      
Debt instrument, increase (decrease), net   90  
NorthStar Clean Energy, Including Subsidiaries | Construction Financing Agreement, Second Half Of 2026 | Construction financing agreement      
Debt Instrument [Line Items]      
Debt instrument, increase (decrease), net   287  
NorthStar Clean Energy, Including Subsidiaries | Construction Financing Agreement, Second Half Of 2026 | Construction financing agreement | Subsequent Event      
Debt Instrument [Line Items]      
Debt conversion, converted instrument, amount 55    
Convertible debt 74    
Repayments to be made $ 103    
NorthStar Clean Energy, Including Subsidiaries | Construction Financing Agreement, First Half Of 2026 | Construction financing agreement      
Debt Instrument [Line Items]      
Debt conversion, converted instrument, amount   114  
NorthStar Clean Energy, Including Subsidiaries | Term Loan | Subsequent Event      
Debt Instrument [Line Items]      
Debt instrument, term (in years) 5 years    
CMS Energy      
Debt Instrument [Line Items]      
Repayments of debt   $ 300  
CMS Energy | Senior notes | Senior notes      
Debt Instrument [Line Items]      
Debt instrument, interest rate, stated (in percent)   3.00%  
Repayments of debt   $ 300