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, 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										39
Common stock repurchased										(11)
Common stock reissued										10
Stockholder contribution		150
Amortization of net actuarial loss				2				2				2				2
Unrealized gain (loss) on investments, net of tax					(2)			(2)					(1)			(1)
Reclassification adjustments included in net income, net of tax					(5)			5
Net income (loss) attributable to CMS Energy																269
Net income						299		299						269		270
Dividends declared on common stock						(254)								(160)
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, 2015	841	3,724	(12)	(24)	12	876	37	5,466	3	4,812	(48)	(46)	(2)	(949)	37	3,855
Total Equity, beginning at Mar. 31, 2015	841	3,724	(11)	(25)	14	925	37	5,516	3	4,783	(48)	(47)	(1)	(936)	37	3,839
Common stock issued										29
Common stock repurchased
Stockholder contribution
Amortization of net actuarial loss				1				1				1				1
Unrealized gain (loss) on investments, net of tax					(2)			(2)					(1)			(1)
Reclassification adjustments included in net income, net of tax
Net income (loss) attributable to CMS Energy																67
Net income						84		84						67		68
Dividends declared on common stock						(132)								(80)
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, 2015	841	3,724	(12)	(24)	12	876	37	5,466	3	4,812	(48)	(46)	(2)	(949)	37	3,855
Total Equity, beginning at Mar. 31, 2015	841	3,724	(11)	(25)	14	925	37	$ 5,516	3	4,783	(48)	(47)	(1)	(936)	37	3,839
Common stock issued																$ 90
Number of Shares Issued																2,337,781
End of period, shares at Jun. 30, 2016								84,100,000								279,300,000
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 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								277,200,000
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, net of tax					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)
End of period, shares at Jun. 30, 2016								84,100,000								279,300,000
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, net of tax					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)
End of period, shares at Jun. 30, 2016								84,100,000								279,300,000
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