Stock-Based Compensation (Schedule Of Restricted Stock Granted) (Details)	12 Months Ended
	Dec. 31, 2020 shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)	527,400
Consumers Energy Company
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)	504,755
Time-lapse awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)	106,520
Time-lapse awards | Consumers Energy Company
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)	101,439
Market-based awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)	123,246
Market-based awards | Consumers Energy Company
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)	118,011
Performance-based awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)	123,246
Performance-based awards | Consumers Energy Company
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)	118,011
Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)	13,405
Restricted stock units | Consumers Energy Company
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)	12,800
Dividends on market-based awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)	17,937
Dividends on market-based awards | Consumers Energy Company
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)	17,152
Dividends on performance-based awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)	17,505
Dividends on performance-based awards | Consumers Energy Company
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)	16,736
Dividends on restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)	1,669
Dividends on restricted stock units | Consumers Energy Company
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)	1,609
Additional market-based shares based on achievement of condition
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)	71,678
Additional market-based shares based on achievement of condition | Consumers Energy Company
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)	68,857
Additional performance-based shares based on achievement of condition
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)	52,194
Additional performance-based shares based on achievement of condition | Consumers Energy Company
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)	50,140