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			54
Common stock repurchased			(10)
Common stock reissued			20
Stockholder contribution													250
Amortization of net actuarial loss	3				3						2				2
Amortization of prior service credit	(1)				(1)
Unrealized loss on investments	(1)					(1)					(1)					(1)
Reclassification adjustments included in net income	1					1					1					1
Unrealized loss on derivative instruments, net of tax of $-, $-, $(1), and $-	0
Net income	550								549	1	574						574
Dividends declared on common stock									(304)								(392)
Dividends declared on preferred stock																	(1)
Distributions and other changes in noncontrolling interests										(1)
Total Equity at End of Period at Sep. 30, 2018	$ 4,786	3	5,083	(59)	(59)	0		0	(278)	37	6,923	841	4,699	(27)	(27)	0	1,373	37
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends declared per common share (in dollars per share)	$ 1.0725
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 $-, $-, $(1), and $-								0
Total Equity at End of Period at Dec. 31, 2018	4,792	3	5,088	(65)	(63)	0	$ (2)		(271)	37	6,920	841	4,699	(21)	(21)	0	1,364	37
Total Equity at Beginning of Period at Jun. 30, 2018	4,709	3	5,076	(61)	(60)	(1)		0	(346)	37	6,888	841	4,699	(29)	(28)	(1)	1,340	37
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock issued			7
Common stock repurchased			0
Common stock reissued			0
Stockholder contribution													0
Amortization of net actuarial loss	1				1						1				1
Amortization of prior service credit	0				0
Unrealized loss on investments	0					0					0					0
Reclassification adjustments included in net income	1					1					1					1
Unrealized loss on derivative instruments, net of tax of $-, $-, $(1), and $-	0							0
Net income	169								169	0	180						180
Dividends declared on common stock									(101)								(147)
Dividends declared on preferred stock																	0
Distributions and other changes in noncontrolling interests										0
Total Equity at End of Period at Sep. 30, 2018	$ 4,786	3	5,083	(59)	(59)	0		$ 0	(278)	37	6,923	841	4,699	(27)	(27)	0	1,373	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, 2018	$ 4,792	3	5,088	(65)	(63)	0	(2)		(271)	37	6,920	841	4,699	(21)	(21)	0	1,364	37
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock issued			25
Common stock repurchased			(9)
Common stock reissued			0
Stockholder contribution													675
Amortization of net actuarial loss	2				2						1				1
Amortization of prior service credit	(1)				(1)
Unrealized loss on investments	0					0					0					0
Reclassification adjustments included in net income	0					0					0					0
Unrealized loss on derivative instruments	(3)						(3)
Net income	514								513	1	537						537
Dividends declared on common stock									(325)								(396)
Dividends declared on preferred stock																	(1)
Distributions and other changes in noncontrolling interests										(1)
Total Equity at End of Period at Sep. 30, 2019	$ 4,994	3	5,104	(67)	(62)	0	(5)		(83)	37	7,736	841	5,374	(20)	(20)	0	1,504	37
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends declared per common share (in dollars per share)	$ 1.1475
Total Equity at Beginning of Period at Jun. 30, 2019	$ 4,888	3	5,097	(67)	(62)	0	(5)		(182)	37	7,647	841	5,374	(20)	(20)	0	1,415	37
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock issued			8
Common stock repurchased			(1)
Common stock reissued			0
Stockholder contribution													0
Amortization of net actuarial loss	0				0						0				0
Amortization of prior service credit	0				0
Unrealized loss on investments	0					0					0					0
Reclassification adjustments included in net income	0					0					0					0
Unrealized loss on derivative instruments	0						0
Net income	207								207	0	213						213
Dividends declared on common stock									(108)								(124)
Dividends declared on preferred stock																	0
Distributions and other changes in noncontrolling interests										0
Total Equity at End of Period at Sep. 30, 2019	$ 4,994	$ 3	$ 5,104	$ (67)	$ (62)	$ 0	$ (5)		$ (83)	$ 37	$ 7,736	$ 841	$ 5,374	$ (20)	$ (20)	$ 0	$ 1,504	$ 37
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends declared per common share (in dollars per share)	$ 0.3825