Stock-based Compensation (Summary of Weighted-average Grant-date Fair Value) (Details) - $ / shares	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Restricted stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in dollars per share)	$ 52.62	$ 48.69	$ 43.52
Restricted stock | Consumers Energy Company
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in dollars per share)	52.42	48.57	42.85
Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in dollars per share)	50.32	56.13	54.11
Restricted stock units | Consumers Energy Company
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in dollars per share)	$ 50.34	$ 56.07	$ 53.93