Schedule I - Condensed Financial Information of Registrant (Narrative) (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Condensed Financial Statements, Captions [Line Items]
Issuance of preferred stock, net of issuance costs	$ 224	$ 0	$ 0
Series C Preferred Stock Depositary Shares
Condensed Financial Statements, Captions [Line Items]
Number of shares outstanding (in shares)	9,200,000
Trading symbol	CMS PRC
Issue price (in dollars per share)	$ 25.00
Issuance of preferred stock, net of issuance costs	$ 224
Dividend rate	4.20%
Optional redemption price (in dollars per share)	$ 25.00
Series C Preferred Stock
Condensed Financial Statements, Captions [Line Items]
Optional redemption price (in dollars per share)	$ 25,000
CMS Energy
Condensed Financial Statements, Captions [Line Items]
Maximum potential obligation	$ 633
Issuance of preferred stock, net of issuance costs	$ 224	$ 0	$ 0
CMS Energy Note Payable
Condensed Financial Statements, Captions [Line Items]
Interest rate	4.10%