Financings and Capitalization (Issuance of Convertible Senior Notes) (Details) $ / shares in Units, $ in Millions	1 Months Ended
May 31, 2023 USD ($) d $ / shares	Sep. 30, 2023 USD ($)
Debt Instrument [Line Items]
Principal (In Millions)		$ 2,910
CMS Energy
Debt Instrument [Line Items]
Principal (In Millions)		800
3.375% Convertible Senior Notes Due 2028 \| Convertible debt \| CMS Energy
Debt Instrument [Line Items]
Principal (In Millions)	$ 800	$ 800
Interest rate	3.375%	3.375%
Unamortized issuance costs	$ 12
Conversion ratio	0.0135194
Conversion price (in dollars per share) \| $ / shares	$ 73.97
Threshold percentage of stock price trigger	130.00%
Threshold trading days \| d	20
Threshold consecutive trading days \| d	30
Redemption price percentage	100.00%

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