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										10
Common stock repurchased										(11)
Common stock reissued										10
Stockholder contribution		150
Amortization of net actuarial loss				1				1				1				1
Reclassification adjustments included in net income, net of tax					(5)			5
Net income						215		215						202		202
Dividends declared on common stock						(122)								(80)
Total Equity, end 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 Mar. 31, 2016								84,100,000								279,200,000
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
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										70
Common stock repurchased										(10)
Stockholder contribution		150
Amortization of net actuarial loss
Unrealized gain on investments, net of tax					$ 3			$ 3
Reclassification adjustments included in net income, net of tax
Net income						172		$ 172						164		$ 164
Dividends declared on common stock						(155)								(86)
End of period, shares at Mar. 31, 2016								84,100,000								279,200,000
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