Document And Entity Information - shares	6 Months Ended
	Jun. 30, 2018	Jul. 11, 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
Document Type	10-Q
Document Period End Date	Jun. 30, 2018
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	Q2
Amendment Flag	false
Entity Common Stock, Shares Outstanding		283,265,427
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 Common Stock, Shares Outstanding		84,108,789