Consolidated Statements of Changes In Equity (Unaudited) - USD ($) $ in Millions	Total	Common Stock	Other Paid-in Capital	Accumulated Other Comprehensive Loss	Retirement benefits liability	Investments	Accumulated Deficit	Noncontrolling Interests	Consumers Energy Company	Consumers Energy Company Common Stock	Consumers Energy Company Other Paid-in Capital	Consumers Energy Company Accumulated Other Comprehensive Loss	Consumers Energy Company Retirement benefits liability	Consumers Energy Company Investments	Consumers Energy Company Accumulated Deficit	Consumers Energy Company Preferred Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of change in accounting principle					$ 0		$ 0						$ 0	$ 0	$ 0
Total Equity at Beginning of Period at Dec. 31, 2016	$ 4,290	$ 3	$ 4,916	$ (50)	(50)	$ 0	(616)	$ 37	$ 5,939	$ 841	$ 3,999	$ (3)	(21)	18	1,065	$ 37
Increase (Decrease) in Stockholders' Equity [Roll Forward]
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	1					1			2					2
Reclassification adjustments included in net income									(8)					(8)
Amortization of prior service credit	0				0
Net income	292						291	1	315						315
Dividends declared on common stock							(187)								(236)
Dividends declared on preferred stock															(1)
Distributions and other changes in noncontrolling interests								(1)
Total Equity at End of Period at Jun. 30, 2017	4,486	3	5,006	(48)	(49)	1	(512)	37	6,462	841	4,449	(8)	(20)	12	1,143	37
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of change in accounting principle					0		0						0	0	0
Total Equity at Beginning of Period at Mar. 31, 2017	4,407	3	4,927	(49)	(50)	1	(511)	37	6,246	841	4,249	(9)	(21)	12	1,128	37
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock issued			80
Common stock repurchased			(1)
Common stock reissued			0
Stockholder contribution											200
Amortization of net actuarial loss	1				1				1				1
Unrealized gain (loss) on investments	0					0			0					0
Reclassification adjustments included in net income									0					0
Amortization of prior service credit	0				0
Net income	93						92	1	104						104
Dividends declared on common stock							(93)								(88)
Dividends declared on preferred stock															(1)
Distributions and other changes in noncontrolling interests								(1)
Total Equity at End of Period at Jun. 30, 2017	4,486	3	5,006	(48)	(49)	1	(512)	37	6,462	841	4,449	(8)	(20)	12	1,143	37
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of change in accounting principle					(11)		8						(5)	(12)	19
Total Equity at Beginning of Period at Dec. 31, 2017	4,478	3	5,019	(50)	(50)	0	(531)	37	6,488	841	4,449	(12)	(24)	12	1,173	37
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock issued			47
Common stock repurchased			(10)
Common stock reissued			20
Stockholder contribution											250
Amortization of net actuarial loss	2				2				1				1
Unrealized gain (loss) on investments	(1)					(1)			(1)					(1)
Reclassification adjustments included in net income									0					0
Amortization of prior service credit	(1)				(1)
Net income	381						380	1	394						394
Dividends declared on common stock							(203)								(245)
Dividends declared on preferred stock															(1)
Distributions and other changes in noncontrolling interests								(1)
Total Equity at End of Period at Jun. 30, 2018	4,709	3	5,076	(61)	(60)	(1)	(346)	37	6,888	841	4,699	(29)	(28)	(1)	1,340	37
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of change in accounting principle					0		0						0	0	0
Total Equity at Beginning of Period at Mar. 31, 2018	4,633	3	5,037	(61)	(60)	(1)	(383)	37	6,713	841	4,549	(29)	(28)	(1)	1,315	37
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock issued			39
Common stock repurchased			0
Common stock reissued			0
Stockholder contribution											150
Amortization of net actuarial loss	1				1				0				0
Unrealized gain (loss) on investments	0					0			0					0
Reclassification adjustments included in net income									0					0
Amortization of prior service credit	(1)				(1)
Net income	140						139	1	152						152
Dividends declared on common stock							(102)								(126)
Dividends declared on preferred stock															(1)
Distributions and other changes in noncontrolling interests								(1)
Total Equity at End of Period at Jun. 30, 2018	$ 4,709	$ 3	$ 5,076	$ (61)	$ (60)	$ (1)	$ (346)	$ 37	$ 6,888	$ 841	$ 4,699	(29)	$ (28)	$ (1)	$ 1,340	$ 37
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of change in accounting principle												$ (19)