Contingencies And Commitments (Guarantees) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013 MW		Dec. 31, 2012	Dec. 31, 2011
Consumers Energy Company [Member]
Guarantor Obligations [Line Items]
Expiration Date	Various through September 2029
Maximum obligation	$ 30
Carrying Amount	1
Guarantees [Member]
Guarantor Obligations [Line Items]
Expiration Date	Various through March 2021
Maximum obligation	57
Indemnity Obligations From Asset Sales And Other Agreements [Member]
Guarantor Obligations [Line Items]
Expiration Date	Various through September 2029	[1]
Maximum obligation	471	[1]
Carrying Amount	16	[1]
Non-Related Parties [Member]
Guarantor Obligations [Line Items]
Purchase Obligations Total	12,068
Purchase Obligations Due in Year One	1,879
Purchase Obligations Due in Year Two	983
Purchase Obligations Due in Year Three	1,032
Purchase Obligations Due in Year Four	1,001
Purchase Obligations Due in Year Five	1,006
Purchase Obligations Due After Year Five	6,167
Non-Related Parties [Member] | Consumers Energy Company [Member]
Guarantor Obligations [Line Items]
Purchase Obligations Total	11,838
Purchase Obligations Due in Year One	1,803
Purchase Obligations Due in Year Two	955
Purchase Obligations Due in Year Three	1,005
Purchase Obligations Due in Year Four	974
Purchase Obligations Due in Year Five	979
Purchase Obligations Due After Year Five	6,122
Related Parties [Member]
Guarantor Obligations [Line Items]
Purchase Obligations Total	1,244
Purchase Obligations Due in Year One	89
Purchase Obligations Due in Year Two	84
Purchase Obligations Due in Year Three	86
Purchase Obligations Due in Year Four	88
Purchase Obligations Due in Year Five	87
Purchase Obligations Due After Year Five	810
Related Parties [Member] | Consumers Energy Company [Member]
Guarantor Obligations [Line Items]
Purchase Obligations Total	1,244
Purchase Obligations Due in Year One	89
Purchase Obligations Due in Year Two	84
Purchase Obligations Due in Year Three	86
Purchase Obligations Due in Year Four	88
Purchase Obligations Due in Year Five	87
Purchase Obligations Due After Year Five	810
MCV PPA [Member] | Consumers Energy Company [Member]
Guarantor Obligations [Line Items]
Term of Unrecorded Unconditional Purchase Obligations	35 years
Unrecorded Unconditional Purchase Obligations, Minimum Quantity Required	1,240
Unrecorded Unconditional Purchase Obligation Capacity Charge Per Mwh	10.14
Unrecorded Unconditional Purchase Obligation, Annual Contribution to Renewable Resources Program By Counterparty	5
Unrecorded Unconditional Purchase Obligation, Contract Extension Period	5 years
Unrecorded Unconditional Purchase Obligation, Purchases	278		319	292
Unrecorded Unconditional Purchase Obligation, Estimated Average Capacity and Energy Charges	320
Palisades PPA [Member] | Consumers Energy Company [Member]
Guarantor Obligations [Line Items]
Unrecorded Unconditional Purchase Obligation, Purchases	338		331	311
Unrecorded Unconditional Purchase Obligation, Estimated Average Capacity and Energy Charges	$ 370
Unrecorded Unconditional Purchase Obligations, Maximum Quantity	798

[1] The majority of this amount arises from stock and asset sale agreements under which CMS Energy or a subsidiary of CMS Energy, other than Consumers, indemnified the purchaser for losses resulting from various matters, including claims related to tax disputes, claims related to power purchase agreements, and defects in title to the assets or stock sold to the purchaser by CMS Energy subsidiaries. Except for items described elsewhere in this Note, CMS Energy believes the likelihood of material loss to be remote for the indemnity obligations not recorded as liabilities