Document And Entity Information - shares	9 Months Ended
	Sep. 30, 2018	Oct. 09, 2018
Document Information [Line Items]
Entity Registrant Name	CMS Energy Corporation
Trading Symbol	cms
Entity Central Index Key	0000811156
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Emerging Growth Company	false
Entity Small Business	false
Document Type	10-Q
Document Period End Date	Sep. 30, 2018
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	Q3
Amendment Flag	false
Entity Common Stock, Shares Outstanding		283,331,416
Consumers Energy Company
Document Information [Line Items]
Entity Registrant Name	Consumers Energy Company
Entity Central Index Key	0000201533
Entity Filer Category	Non-accelerated Filer
Entity Emerging Growth Company	false
Entity Small Business	false
Entity Common Stock, Shares Outstanding		84,108,789