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, 2012	$ 841	$ 3,107	$ (8)	$ (25)	$ 17	$ 598	$ 44	$ 4,582	$ 3	$ 4,669	$ (55)	$ (56)	$ 2	$ (1)	$ (1,423)	$ 44	$ 3,238
Common stock issued										29
Common stock repurchased
Common stock reissued										5
Stockholder contribution		150						150
Amortization of net actuarial loss				1				1				1					1
Unrealized gain (loss) on investments, net of tax					4			4
Reclassification adjustments included in net income, net of tax					(3)			3
Reclassification adjustments included in net income
Net income attributable to CMS Energy															144
Net income						162		162									144
Common stock dividends declared						(93)									(67)
Total Equity, end at Mar. 31, 2013	841	3,257	(6)	(24)	18	667	44	4,803	3	4,703	(54)	(55)	2	(1)	(1,346)	44	3,350
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)
Common stock reissued
Stockholder contribution		150						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 attributable to CMS Energy															204
Net income						221		221									204
Common stock dividends declared						(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