Earnings Per Share - CMS Energy (Narrative) (Details) - USD ($) $ in Millions	Dec. 31, 2023	May 31, 2023
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Principal (In Millions)	$ 3,556
CMS Energy
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Principal (In Millions)	800
CMS Energy \| 3.375% Convertible Senior Notes Due 2028 \| Convertible debt
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Principal (In Millions)	$ 800	$ 800

Face (par) amount of debt instrument at time of issuance.

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