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										79
Common stock repurchased										(10)
Stockholder contribution		275
Amortization of net actuarial loss												1				1
Amortization of prior service credit												(1)				(1)
Unrealized gain (loss) on investments					5			5
Reclassification adjustments included in net income, net of tax
Net income (loss) attributable to CMS Energy																288
Net Income						304		304						288		289
Dividends declared on common stock						(213)								(172)
Dividends declared on preferred stock						(1)
Income Attributable to Noncontrolling Interests															1	1
Distributions, and other changes in noncontrolling interests															(1)
Total Equity, end at Jun. 30, 2016	841	3,999	(1)	(19)	18	1,040	37	5,916	3	4,906	(47)	(43)	(4)	(706)	37	4,193
Total Equity, beginning at Mar. 31, 2016	841	3,874	(3)	(19)	16	967	37	5,716	3	4,897	(47)	(43)	(4)	(744)	37	4,146
Common stock issued										9
Common stock repurchased
Stockholder contribution		125
Amortization of net actuarial loss												1				1
Amortization of prior service credit												(1)				(1)
Unrealized gain (loss) on investments					2			2
Reclassification adjustments included in net income, net of tax
Net income (loss) attributable to CMS Energy																124
Net Income						132		132						124		125
Dividends declared on common stock						(58)								(86)
Dividends declared on preferred stock						(1)
Income Attributable to Noncontrolling Interests															1	1
Distributions, and other changes in noncontrolling interests															(1)
Total Equity, end at Jun. 30, 2016	841	3,999	(1)	(19)	18	1,040	37	5,916	3	4,906	(47)	(43)	(4)	(706)	37	4,193
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										88
Common stock repurchased										(13)
Common stock reissued										15
Stockholder contribution		450
Amortization of net actuarial loss				(1)				1				1				1
Unrealized gain (loss) on investments					2			2					1			1
Reclassification adjustments included in net income, net of tax					(8)			(8)
Net income (loss) attributable to CMS Energy																291
Net Income						315		315						291		292
Dividends declared on common stock						(236)								(187)
Dividends declared on preferred stock						(1)
Income Attributable to Noncontrolling Interests															1	1
Distributions, and other changes in noncontrolling interests															(1)
Total Equity, end at Jun. 30, 2017	841	4,449	(8)	(20)	12	1,143	37	6,462	3	5,006	(48)	(49)	1	(512)	37	4,486
Total Equity, beginning 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
Common stock issued										80
Common stock repurchased										(1)
Stockholder contribution		200
Amortization of net actuarial loss				(1)				1				1				1
Reclassification adjustments included in net income, net of tax
Net income (loss) attributable to CMS Energy																92
Net Income						104		104						92		93
Dividends declared on common stock						(88)								(93)
Dividends declared on preferred stock						(1)
Income Attributable to Noncontrolling Interests															1	1
Distributions, and other changes in noncontrolling interests															(1)
Total Equity, end at Jun. 30, 2017	$ 841	$ 4,449	$ (8)	$ (20)	$ 12	$ 1,143	$ 37	$ 6,462	$ 3	$ 5,006	$ (48)	$ (49)	$ 1	$ (512)	$ 37	$ 4,486