| Cover | Jun. 29, 2021 |
| Document Information [Line Items] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Jun. 29, 2021 |
| Current Fiscal Year End Date | --12-31 |
| Entity File Number | 1-9513 |
| Entity Registrant Name | CMS ENERGY CORPORATION |
| Entity Central Index Key | 0000811156 |
| 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 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | false |
| Common Stock [Member] | |
| 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 |
| A 5.625 Junior Subordinated Notes Due 2078 Member | |
| 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 |
| A 5.875 Junior Subordinated Notes Due 2078 Member | |
| 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 |
| A 5.875 Junior Subordinated Notes Due 2079 Member | |
| 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 |
