Stock-Based Compensation (Schedule Of Restricted Stock Granted) (Details)	12 Months Ended
	Dec. 31, 2016 shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted	841,413
Consumers Energy Company [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted	801,235
Time-Lapsed Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted	188,303
Time-Lapsed Restricted Stock [Member] | Consumers Energy Company [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted	180,958
Market-Based Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted	185,464
Market-Based Restricted Stock [Member] | Consumers Energy Company [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted	175,818
Performance-Based Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted	185,464
Performance-Based Restricted Stock [Member] | Consumers Energy Company [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted	175,818
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted	15,338
Restricted Stock Units (RSUs) [Member] | Consumers Energy Company [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted	14,907
Time-Lapsed Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted	14,595
Time-Lapsed Restricted Stock Units [Member] | Consumers Energy Company [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted	14,186
Dividends On Market-Based Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted	38,652
Dividends On Market-Based Awards [Member] | Consumers Energy Company [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted	36,646
Dividends On Performance-Based Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted	14,438
Dividends On Performance-Based Awards [Member] | Consumers Energy Company [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted	13,704
Dividends On Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted	743
Dividends On Restricted Stock Units [Member] | Consumers Energy Company [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted	721
Additional Market-Based Shares Based On Achievement Of Condition [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted	213,754
Additional Market-Based Shares Based On Achievement Of Condition [Member] | Consumers Energy Company [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted	203,384