Financings and Capitalization (Schedule of Revolving Credit Facilities) (Details)	9 Months Ended
	Sep. 30, 2025 USD ($)
Consumers Energy Company | Letter of Credit
Line of Credit Facility [Line Items]
Borrowings	$ 0
Consumers Energy Company | Revolving Credit Facilities December 14, 2027
Line of Credit Facility [Line Items]
Amount of Facility	1,100,000,000
Amount Borrowed	0
Letters of Credit Outstanding	10,000,000
Amount Available	1,090,000,000
Consumers Energy Company | Revolving Credit Facilities November 18, 2025
Line of Credit Facility [Line Items]
Amount of Facility	250,000,000
Amount Borrowed	0
Letters of Credit Outstanding	112,000,000
Amount Available	138,000,000
Consumers Energy Company | Revolving Credit Facilities March 31, 2028
Line of Credit Facility [Line Items]
Amount of Facility	50,000,000
Amount Borrowed	0
Letters of Credit Outstanding	42,000,000
Amount Available	8,000,000
CMS Energy | Revolving Credit Facilities December 14, 2027
Line of Credit Facility [Line Items]
Amount of Facility	550,000,000
Amount Borrowed	0
Letters of Credit Outstanding	35,000,000
Amount Available	515,000,000
CMS Energy | Revolving Credit Facilities December 14, 2027 | Letter of Credit
Line of Credit Facility [Line Items]
Borrowings	0
CMS Energy | Revolving Credit Facilities September 30, 2026
Line of Credit Facility [Line Items]
Amount of Facility	50,000,000
Amount Borrowed	0
Letters of Credit Outstanding	50,000,000
Amount Available	0
NorthStar Clean Energy, Including Subsidiaries | Revolving Credit Facilities May 30, 2028
Line of Credit Facility [Line Items]
Amount of Facility	250,000,000
Amount Borrowed	180,000,000
Letters of Credit Outstanding	8,000,000
Amount Available	62,000,000
Equity interests	515,000,000
NorthStar Clean Energy, Including Subsidiaries | Revolving Credit Facilities December 25, 2025
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 | Revolving Credit Facilities Upon Completion of Construction Project
Line of Credit Facility [Line Items]
Amount of Facility	19,000,000
Amount Borrowed	0
Letters of Credit Outstanding	12,000,000
Amount Available	$ 7,000,000