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	Derivative instruments	Derivative instruments	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
Total Equity at Beginning of Period at Dec. 31, 2017	$ 4,478	$ 3	$ 5,019	$ (50)	$ (50)	$ 0	$ 0		$ (531)	$ 37	$ 6,488	$ 841	$ 4,449	$ (12)	$ (24)	$ 12	$ 1,173	$ 37
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock issued			8
Common stock repurchased			(10)
Common stock reissued			20
Stockholder contribution													100
Amortization of net actuarial loss	1				1						1				1
Amortization of prior service credit	0				0
Unrealized loss on investments	(1)					(1)					(1)					(1)
Unrealized loss on derivative instruments, net of tax of $- for both periods	0
Net income	241								241		242						242
Dividends declared on common stock									(101)								(119)
Total Equity at End of Period at Mar. 31, 2018	$ 4,633	3	5,037	(61)	(60)	(1)	0		(383)	37	6,713	841	4,549	(29)	(28)	(1)	1,315	37
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends declared per common share (in dollars per share)	$ 0.3575
Total Equity at Beginning of Period at Dec. 31, 2017	$ 4,478	3	5,019	(50)	(50)	0	0		(531)	37	6,488	841	4,449	(12)	(24)	12	1,173	37
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Unrealized loss on derivative instruments, net of tax of $- for both periods							$ 0
Total Equity at End of Period at Dec. 31, 2018	4,792	3	5,088	(65)	(63)	0		$ (2)	(271)		6,920	841	4,699	(21)	(21)	0	1,364	37
Noncontrolling interests	37									37
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock issued			7
Common stock repurchased			(8)
Common stock reissued			0
Stockholder contribution													350
Amortization of net actuarial loss	1				1						0				0
Amortization of prior service credit	(1)				(1)
Unrealized loss on investments	0					0					0					0
Unrealized loss on derivative instruments	(1)							(1)
Net income	213								213		226						226
Dividends declared on common stock									(108)								(172)
Total Equity at End of Period at Mar. 31, 2019	$ 4,895	$ 3	$ 5,087	$ (66)	$ (63)	$ 0		$ (3)	$ (166)		$ 7,324	$ 841	$ 5,049	$ (21)	$ (21)	$ 0	$ 1,418	$ 37
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends declared per common share (in dollars per share)	$ 0.3825
Noncontrolling interests	$ 37									$ 37