Asset Retirement Obligations (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
ARO Liability, at beginning of period	$ 553	$ 477
Incurred	71	65
Settled	(53)	(41)
Accretion	24	24
Cash Flow Revisions	33	28
ARO Liability, end of period	628	553
Consumers Energy Company
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
ARO Liability, at beginning of period	530	474
Incurred	71	46
Settled	(53)	(41)
Accretion	24	23
Cash Flow Revisions	33	28
ARO Liability, end of period	605	530
Renewable generation assets
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
ARO Liability, at beginning of period	23	3
Incurred	0	19
Settled	0	0
Accretion	0	1
Cash Flow Revisions	0	0
ARO Liability, end of period	23	23
Renewable generation assets | Consumers Energy Company
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
ARO Liability, at beginning of period	74	21
Incurred	16	24
Settled	0	0
Accretion	3	1
Cash Flow Revisions	0	28
ARO Liability, end of period	93	74
Coal ash disposal areas | Consumers Energy Company
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
ARO Liability, at beginning of period	148	166
Incurred	0	0
Settled	(34)	(24)
Accretion	5	6
Cash Flow Revisions	38	0
ARO Liability, end of period	157	148
Gas distribution cut, purge, and cap | Consumers Energy Company
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
ARO Liability, at beginning of period	240	231
Incurred	39	1
Settled	(10)	(5)
Accretion	13	13
Cash Flow Revisions	0	0
ARO Liability, end of period	282	240
Asbestos abatement | Consumers Energy Company
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
ARO Liability, at beginning of period	36	34
Incurred	0	0
Settled	0	0
Accretion	2	2
Cash Flow Revisions	0	0
ARO Liability, end of period	38	36
Gas wells plug and abandon | Consumers Energy Company
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
ARO Liability, at beginning of period	32	22
Incurred	16	16
Settled	(9)	(7)
Accretion	1	1
Cash Flow Revisions	(5)	0
ARO Liability, end of period	35	32
Cable under Straits of Mackinac | Consumers Energy Company
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
ARO Liability, at beginning of period	$ 0	0
Incurred		5
Settled		(5)
Accretion		0
Cash Flow Revisions		0
ARO Liability, end of period		$ 0