v3.26.1
Financings and Capitalization (Schedule of Revolving Credit Facilities) (Details)
 6 Months Ended
Jun. 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 53,000,000
Amount Available 1,047,000,000
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 100,000,000
Amount Available 0
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 41,000,000
Amount Available 9,000,000
Consumers Energy Company | Unsecured Letter Of Credit Facility  
Line of Credit Facility [Line Items]  
Amount of Facility 97,000,000
Amount Borrowed 0
Letters of Credit Outstanding 97,000,000
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
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
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 35,000,000
Amount Available 715,000,000
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 0
Letters of Credit Outstanding 137,000,000
Amount Available 163,000,000
Equity interests 622,000,000
NorthStar Clean Energy, Including Subsidiaries | Secured Letter Of Credit Facility, Expiring September 2028  
Line of Credit Facility [Line Items]  
Amount of Facility 37,000,000
Amount Borrowed 0
Letters of Credit Outstanding 37,000,000
Amount Available 0
NorthStar Clean Energy, Including Subsidiaries | Secured Revolving 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