Stock-Based Compensation (Share-Based Compensation Arrangement By Share-Based Payment Award, Options, Grants In Period, Weighted Average Grant Date Fair Value) (Details) (USD $)	12 Months Ended
	Dec. 31, 2013		Dec. 31, 2012	Dec. 31, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-Average Grant Date Fair Value per Share, Granted	$ 16.65	[1]
Consumers Energy Company [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-Average Grant Date Fair Value per Share, Granted	$ 16.76	[1]
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-Average Grant Date Fair Value per Share, Granted	$ 16.65		$ 12.32	$ 13.89
Restricted Stock [Member] | Consumers Energy Company [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-Average Grant Date Fair Value per Share, Granted	$ 16.76		$ 12.28	$ 14.17

[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.