Consolidated Statements Of Changes In Equity (USD $) In Millions	Consumers Energy Company [Member] CMS Energy Common Stock [Member]	Consumers Energy Company [Member] Other Paid-in Capital [Member]	Consumers Energy Company [Member] Accumulated Other Comprehensive Income (Loss) [Member]	Consumers Energy Company [Member] Retirement Benefits Liability [Member]	Consumers Energy Company [Member] Investments [Member]	Consumers Energy Company [Member] Retained Earnings (Accumulated Deficit) [Member]	Consumers Energy Company [Member] Preferred Stock [Member]	Consumers Energy Company [Member]	CMS Energy Common Stock [Member]	Other Paid-in Capital [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Retirement Benefits Liability [Member]	Investments [Member]	Derivative Instruments [Member]	Retained Earnings (Accumulated Deficit) [Member]	Noncontrolling Interest [Member]	Total
Total Equity, beginning at Dec. 31, 2013	$ 841	$ 3,257	$ (2)	$ (17)	$ 15	$ 724	$ 37	$ 4,857	$ 3	$ 4,715	$ (22)	$ (21)		$ (1)	$ (1,242)	$ 37	$ 3,491
Common stock issued										37
Common stock repurchased										(6)
Stockholder contribution		150
Amortization of net actuarial loss
Unrealized gain (loss) on investments, net of tax					2			2
Reclassification adjustments included in net income, net of tax
Reclassification adjustments included in net income														1			(1)
Net income						221		221							204		204
Dividends declared on common stock						(135)									(72)
Total Equity, end at Mar. 31, 2014	841	3,407		(17)	17	810	37	5,095	3	4,746	(21)	(21)			(1,110)	37	3,655
Total Equity, beginning at Dec. 31, 2014	841	3,574	(7)	(26)	19	832	37	5,277	3	4,774	(49)	(48)	(1)		(1,058)	37	3,707
Beginning of period, shares at Dec. 31, 2014								84.1									275.2
Common stock issued										10
Common stock repurchased										(11)
Common stock reissued										10
Stockholder contribution		150
Amortization of net actuarial loss				1				1				1					1
Reclassification adjustments included in net income, net of tax					(5)			5
Reclassification adjustments included in net income
Net income						215		215							202		202
Dividends declared on common stock						(122)									(80)
Total Equity, end at Mar. 31, 2015	$ 841	$ 3,724	$ (11)	$ (25)	$ 14	$ 925	$ 37	$ 5,516	$ 3	$ 4,783	$ (48)	$ (47)	$ (1)		$ (936)	$ 37	$ 3,839
End of period, shares at Mar. 31, 2015								84.1									276.0