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]	Retained Earnings (Accumulated Deficit) [Member]	Noncontrolling Interest [Member]	Total
Total Equity, beginning at Dec. 31, 2015	$ 841	$ 3,724	$ (6)	$ (19)	$ 13	$ 950	$ 37	$ 5,546	$ 3	$ 4,837	$ (47)	$ (43)	$ (4)	$ (855)	$ 37	$ 3,975
Common stock issued										70
Common stock repurchased										(10)
Stockholder contribution		150
Unrealized gain on investments					3			3
Reclassification adjustments included in net income, net of tax
Net income						172		172						164		164
Dividends declared on common stock						(155)								(86)
Total Equity, end at Mar. 31, 2016	841	3,874	(3)	(19)	16	967	37	5,716	3	4,897	(47)	(43)	(4)	(744)	37	4,146
Cumulative effect of change in accounting principle														33
Total Equity, beginning at Dec. 31, 2016	841	3,999	(3)	(21)	18	1,065	37	5,939	3	4,916	(50)	(50)		(616)	37	4,290
Common stock issued										8
Common stock repurchased										(12)
Common stock reissued										15
Stockholder contribution		250
Unrealized gain on investments					2			2					1			1
Reclassification adjustments included in net income, net of tax					(8)			(8)
Net income						211		211						199		199
Dividends declared on common stock						(148)								(94)
Total Equity, end at Mar. 31, 2017	$ 841	$ 4,249	$ (9)	$ (21)	$ 12	$ 1,128	$ 37	$ 6,246	$ 3	$ 4,927	$ (49)	$ (50)	$ 1	$ (511)	$ 37	$ 4,407