v3.26.3
Financings and Capitalization (Schedule of Revolving Credit Facilities) (Details)
 9 Months Ended
Sep. 30, 2026
USD ($)
Consumers Energy Company | Secured Revolving Credit Facility, Expiring November 2030  
Line of Credit Facility [Line Items]  
Amount of Facility $ 1,100,000,000
Amount Borrowed 0
Letters of Credit Outstanding 28,000,000
Amount Available 1,072,000,000
Consumers Energy Company | Secured Revolving Credit Facility, Expiring November 2028  
Line of Credit Facility [Line Items]  
Amount of Facility 300,000,000
Amount Borrowed 0
Letters of Credit Outstanding 0
Amount Available 300,000,000
Consumers Energy Company | Secured Letter Of Credit Facility, Expiring May 2027  
Line of Credit Facility [Line Items]  
Amount of Facility 100,000,000
Amount Borrowed 0
Letters of Credit Outstanding 67,000,000
Amount Available 33,000,000
Consumers Energy Company | Unsecured Letter Of Credit Facility, Expiring March 2028  
Line of Credit Facility [Line Items]  
Amount of Facility 50,000,000
Amount Borrowed 0
Letters of Credit Outstanding 38,000,000
Amount Available 12,000,000
Consumers Energy Company | Unsecured Letter Of Credit Facility  
Line of Credit Facility [Line Items]  
Amount of Facility 98,000,000
Amount Borrowed 0
Letters of Credit Outstanding 98,000,000
Amount Available 0
Consumers Energy Company | Unsecured Letter Of Credit Facility  
Line of Credit Facility [Line Items]  
Amount of Facility 100,000,000
Amount Borrowed 0
Letters of Credit Outstanding 100,000,000
Amount Available 0
Consumers Energy Company | Unsecured Letter Of Credit Facility  
Line of Credit Facility [Line Items]  
Amount of Facility 106,000,000
Amount Borrowed 0
Letters of Credit Outstanding 106,000,000
Amount Available 0
Consumers Energy Company | Unsecured Letter Of Credit Facility  
Line of Credit Facility [Line Items]  
Amount of Facility 125,000,000
Amount Borrowed 0
Letters of Credit Outstanding 125,000,000
Amount Available 0
CMS Energy | Unsecured Revolving Credit Facility, Expiring November 2030  
Line of Credit Facility [Line Items]  
Amount of Facility 750,000,000
Amount Borrowed 0
Letters of Credit Outstanding 14,000,000
Amount Available 736,000,000
Borrowings 0
CMS Energy | Unsecured Letter Of Credit Facility, Expiring September 2026  
Line of Credit Facility [Line Items]  
Amount of Facility 50,000,000
Amount Borrowed 0
Letters of Credit Outstanding 49,000,000
Amount Available 1,000,000
NorthStar Clean Energy, Including Subsidiaries | Secured Revolving Credit Facility, Expiring May 2028  
Line of Credit Facility [Line Items]  
Amount of Facility 300,000,000
Amount Borrowed 75,000,000
Letters of Credit Outstanding 151,000,000
Amount Available 74,000,000
Equity interests 930,000,000
NorthStar Clean Energy, Including Subsidiaries | Secured Line of Credit Facility, Expiring May 2029  
Line of Credit Facility [Line Items]  
Amount of Facility 75,000,000
Amount Borrowed 0
Letters of Credit Outstanding 0
Amount Available 75,000,000
NorthStar Clean Energy, Including Subsidiaries | Secured Letter Of Credit Facility  
Line of Credit Facility [Line Items]  
Amount of Facility 19,000,000
Amount Borrowed 0
Letters of Credit Outstanding 19,000,000
Amount Available 0
NorthStar Clean Energy, Including Subsidiaries | Secured Letter Of Credit Facility  
Line of Credit Facility [Line Items]  
Amount of Facility 22,000,000
Amount Borrowed 0
Letters of Credit Outstanding 7,000,000
Amount Available $ 15,000,000
Debt instrument, term (in years) 5 years