Asset Retirement Obligations (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Asset Retirement Obligations [Line Items]
ARO Liability, at beginning of period	$ 439	$ 340
Incurred	3	11
Settled	(18)	(6)
Accretion	23	20
Cash flow Revisions		74
ARO Liability, end of period	447	439
Consumers Energy Company [Member]
Asset Retirement Obligations [Line Items]
ARO Liability, at beginning of period	438	339
Incurred	3	11
Settled	(18)	(6)
Accretion	23	20
Cash flow Revisions		74
ARO Liability, end of period	446	438
Gas Treating Plant and Gas Wells [Member]
Asset Retirement Obligations [Line Items]
ARO Liability, at beginning of period	1	1
Incurred
Settled
Accretion
Cash flow Revisions
ARO Liability, end of period	1	1
Coal Ash Disposal Areas [Member] | Consumers Energy Company [Member]
Asset Retirement Obligations [Line Items]
ARO Liability, at beginning of period	200	120
Settled	(8)
Accretion	9	6
Cash flow Revisions		74
ARO Liability, end of period	201	200
Gas Distribution Cut, Purge, Cap [Member] | Consumers Energy Company [Member]
Asset Retirement Obligations [Line Items]
ARO Liability, at beginning of period	178	162
Incurred	2	11
Settled	(9)	(6)
Accretion	11	11
ARO Liability, end of period	182	178
Asbestos Abatement [Member] | Consumers Energy Company [Member]
Asset Retirement Obligations [Line Items]
ARO Liability, at beginning of period	54	51
Settled	(1)
Accretion	3	3
ARO Liability, end of period	56	54
Renewable Generation Assets [Member] | Consumers Energy Company [Member]
Asset Retirement Obligations [Line Items]
ARO Liability, at beginning of period	6	6
Incurred	1
Settled
Accretion
Cash flow Revisions
ARO Liability, end of period	$ 7	$ 6