Stock-Based Compensation (Schedule Of Share-Based Compensation, Restricted Stock Units Award Activity) (Details) (USD $)	12 Months Ended
	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, at beginning of period	1,654,776
Number of Shares, Granted	920,587	[1]
Number of Shares, Vested	(927,164)
Number of Shares, Forfeited	(22,343)
Number of Shares, at end of period	1,625,856
Weighted-Average Grant Date Fair Value per Share, at beginning of period	$ 19.15
Weighted-Average Grant Date Fair Value per Share, Granted	$ 16.65	[1]
Weighted-Average Grant Date Fair Value per Share, Vested	$ 10.85
Weighted-Average Grant Date Fair Value per Share, Forfeited	$ 22.33
Weighted-Average Grant Date Fair Value per Share, at end of period	$ 22.42
Consumers Energy Company [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, at beginning of period	1,547,123
Number of Shares, Granted	879,150	[1]
Number of Shares, Vested	(841,728)
Number of Shares, Forfeited	(22,343)
Number of Shares, at end of period	1,562,202
Weighted-Average Grant Date Fair Value per Share, at beginning of period	$ 19.22
Weighted-Average Grant Date Fair Value per Share, Granted	$ 16.76	[1]
Weighted-Average Grant Date Fair Value per Share, Vested	$ 10.84
Weighted-Average Grant Date Fair Value per Share, Forfeited	$ 22.33
Weighted-Average Grant Date Fair Value per Share, at end of period	$ 22.31
TSR Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted	326,518
TSR Restricted Stock [Member] | Consumers Energy Company [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted	310,454
Time-Lapsed Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted	271,250
Time-Lapsed Restricted Stock [Member] | Consumers Energy Company [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted	264,283
Share Dividend Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted	45,486
Share Dividend Restricted Stock [Member] | Consumers Energy Company [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted	43,450
Market Add-On Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted	277,333
Market Add-On Restricted Stock [Member] | Consumers Energy Company [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted	260,963

[1] During 2013, CMS Energy granted 326,518 TSR shares, 271,250 time-lapse shares, 45,486 shares from dividends paid on TSR shares, and 277,333 shares granted as a result of the outcome of the TSR awards’ market condition. During 2013, Consumers granted 310,454 TSR shares, 264,283 time-lapse shares, 43,450 shares from dividends paid on TSR shares, and 260,963 shares granted as a result of the outcome of the TSR awards’ market condition.