Cover page - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Jan. 10, 2020	Jun. 30, 2019
Document Information [Line Items]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2019
Document Transition Report	false
Entity File Number	1-9513
Entity Registrant Name	CMS ENERGY CORPORATION
Entity Tax Identification Number	38-2726431
Entity Incorporation, State or Country Code	MI
Entity Address, Address Line One	One Energy Plaza
Entity Address, City or Town	Jackson
Entity Address, State or Province	MI
Entity Address, Postal Zip Code	49201
City Area Code	517
Local Phone Number	788‑0550
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filer	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Public Float			$ 16,352
Entity Common Stock, Shares Outstanding		283,882,207
Documents Incorporated by Reference	CMS Energy’s and Consumers’ proxy statement relating to their 2020 Annual Meetings of Shareholders to be held May 1, 2020.
Entity Central Index Key	0000811156
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY
Amendment Flag	false
Consumers Energy Company
Document Information [Line Items]
Entity File Number	1-5611
Entity Registrant Name	CONSUMERS ENERGY COMPANY
Entity Tax Identification Number	38-0442310
Entity Incorporation, State or Country Code	MI
Entity Address, Address Line One	One Energy Plaza
Entity Address, City or Town	Jackson
Entity Address, State or Province	MI
Entity Address, Postal Zip Code	49201
City Area Code	517
Local Phone Number	788‑0550
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filer	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		84,108,789
Documents Incorporated by Reference	CMS Energy’s and Consumers’ proxy statement relating to their 2020 Annual Meetings of Shareholders to be held May 1, 2020.
Entity Central Index Key	0000201533
CMS Energy Corporation Common Stock, $0.01 par value
Document Information [Line Items]
Title of 12(b) Security	CMS Energy Corporation Common Stock, $0.01 par value
Trading Symbol	CMS
Security Exchange Name	NYSE
CMS Energy Corporation 5.625% Junior Subordinated Notes due 2078
Document Information [Line Items]
Title of 12(b) Security	CMS Energy Corporation 5.625% Junior Subordinated Notes due 2078
Trading Symbol	CMSA
Security Exchange Name	NYSE
CMS Energy Corporation 5.875% Junior Subordinated Notes due 2078
Document Information [Line Items]
Title of 12(b) Security	CMS Energy Corporation 5.875% Junior Subordinated Notes due 2078
Trading Symbol	CMSC
Security Exchange Name	NYSE
CMS Energy Corporation 5.875% Junior Subordinated Notes due 2079
Document Information [Line Items]
Title of 12(b) Security	CMS Energy Corporation 5.875% Junior Subordinated Notes due 2079
Trading Symbol	CMSD
Security Exchange Name	NYSE
Consumers Energy Company Cumulative Preferred Stock, $100 par value: $4.50 Series
Document Information [Line Items]
Title of 12(b) Security	Consumers Energy Company Cumulative Preferred Stock, $100 par value: $4.50 Series
Trading Symbol	CMS-PB
Security Exchange Name	NYSE