Earnings Per Share - CMS Energy (Basic And Diluted EPS Computations) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Income available to common stockholders
Income from continuing operations	$ 341	$ 308
Loss attributable to noncontrolling interests	(8)	(7)
Preferred stock dividends	2	0
Income from continuing operations available to common stockholders – basic and diluted	$ 347	$ 315
Average common shares outstanding
Weighted average shares - basic (in shares)	289.3	288.6
Dilutive nonvested stock awards (in shares)	0.5	0.5
Dilutive forward equity sale contracts (in shares)	0.1	0.0
Weighted average shares - diluted (in shares)	289.9	289.1
Income from continuing operations per average common share available to common stockholders
Basic (in dollars per share)	$ 1.20	$ 1.09
Diluted (in dollars per share)	$ 1.20	$ 1.09