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
Beginning of period, shares at Dec. 31, 2013									266,137,000
Common stock issued										59
Number of Shares Issued									9,371,000
Common stock repurchased										(7)
Common stock repurchased, shares									(271,000)
Common stock reissued
Common stock reissued, shares
Conversion option on convertible debt										7
Common stock reacquired, value
Common stock reacquired, shares									(53,000)
Stockholder contribution		495
Return of stockholder contribution		(178)
Net gain arising during the period				(11)				(11)				(29)					(29)
Amortization of net actuarial loss, net of tax				2				2				3					3
Amortization of prior service credit												(1)					(1)
Unrealized gain (loss) on investments, net of tax					4			4					(1)				(1)
Reclassification adjustments included in net income
Reclassification adjustments included in net income														1			(1)
Net income attributable to CMS Energy															477		477
Net income						567		567									479
Dividends declared on common stock						(457)									(293)
Dividends declared on preferred stock						(2)
Income Attributable to Noncontrolling Interests																2	2
Distributions, and other changes in noncontrolling interests																(2)
End of period, shares at Dec. 31, 2014									275,184,000
Total Equity, end 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
Common stock issued										65							$ 30
Number of Shares Issued									2,062,000								888,610
Common stock repurchased										(12)
Common stock repurchased, shares									(306,000)
Common stock reissued										10
Common stock reissued, shares									288,000
Conversion option on convertible debt
Common stock reacquired, value
Common stock reacquired, shares									(65,000)
Stockholder contribution		150
Return of stockholder contribution
Net gain arising during the period				3				3				1					$ 1
Amortization of net actuarial loss, net of tax				4				4				5					5
Amortization of prior service credit												(1)					(1)
Unrealized gain (loss) on investments, net of tax					(1)			(1)					(3)				(3)
Reclassification adjustments included in net income					(5)			5
Reclassification adjustments included in net income
Net income attributable to CMS Energy															523		523
Net income						594		$ 594									525
Dividends declared on common stock						(474)									(320)
Dividends declared on preferred stock						(2)
Income Attributable to Noncontrolling Interests																2	$ 2
Distributions, and other changes in noncontrolling interests																(2)
End of period, shares at Dec. 31, 2015								84,100,000	277,163,000								277,200,000
Total Equity, end at Dec. 31, 2015	841	3,724	(6)	(19)	13	950	37	$ 5,546	$ 3	4,837	(47)	(43)	(4)		(855)	37	$ 3,975
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									275,184,000
Common stock issued																	$ 90
Number of Shares Issued																	2,337,781
End of period, shares at Dec. 31, 2016								84,100,000	279,206,000								279,200,000
Total Equity, end at Dec. 31, 2016	841	3,999	(3)	(21)	18	1,065	37	$ 5,939	$ 3	4,916	(50)	(50)			(616)	37	$ 4,290
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
Beginning of period, shares at Dec. 31, 2015								84,100,000	277,163,000								277,200,000
Common stock issued										90							$ 60
Number of Shares Issued									2,580,000								1,449,171
Common stock repurchased										(11)
Common stock repurchased, shares									(292,000)
Common stock reissued
Common stock reissued, shares
Conversion option on convertible debt
Common stock reacquired, value
Common stock reacquired, shares									(245,000)
Stockholder contribution		275
Return of stockholder contribution
Net gain arising during the period				(3)				$ (3)				(8)					$ (8)
Amortization of net actuarial loss, net of tax				1				1				2					2
Amortization of prior service credit												(1)					(1)
Unrealized gain (loss) on investments, net of tax					3			3					1				1
Reclassification adjustments included in net income
Other-than-temporary impairment included in net income					2			2					3				3
Reclassification adjustments included in net income
Net income attributable to CMS Energy															551		551
Net income						616		$ 616									553
Dividends declared on common stock						(499)									(345)
Dividends declared on preferred stock						(2)
Income Attributable to Noncontrolling Interests																2	$ 2
Distributions, and other changes in noncontrolling interests																(2)
End of period, shares at Dec. 31, 2016								84,100,000	279,206,000								279,200,000
Total Equity, end at Dec. 31, 2016	$ 841	$ 3,999	$ (3)	$ (21)	$ 18	$ 1,065	$ 37	$ 5,939	$ 3	$ 4,916	$ (50)	$ (50)			(616)	$ 37	$ 4,290
Cumulative effect of change in accounting principle															$ 33		$ 33