Asset Retirement Obligations (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2015	Dec. 31, 2014
Asset Retirement Obligations [Line Items]
ARO Liability, at beginning of period	$ 340	$ 325
Incurred	11	9
Settled	(6)	(12)
Accretion	20	$ 18
Cash flow Revisions	74
ARO Liability, end of period	439	$ 340
Consumers Energy Company [Member]
Asset Retirement Obligations [Line Items]
ARO Liability, at beginning of period	339	324
Incurred	11	9
Settled	(6)	(12)
Accretion	20	$ 18
Cash flow Revisions	74
ARO Liability, end of period	438	$ 339
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	120	118
Settled		(3)
Accretion	6	$ 5
Cash flow Revisions	74
ARO Liability, end of period	200	$ 120
Gas Distribution Cut, Purge, Cap [Member] \| Consumers Energy Company [Member]
Asset Retirement Obligations [Line Items]
ARO Liability, at beginning of period	162	154
Incurred	11	6
Settled	(6)	(8)
Accretion	11	$ 10
Cash flow Revisions
ARO Liability, end of period	178	$ 162
Asbestos Abatement [Member] \| Consumers Energy Company [Member]
Asset Retirement Obligations [Line Items]
ARO Liability, at beginning of period	51	49
Settled		(1)
Accretion	3	$ 3
Cash flow Revisions
ARO Liability, end of period	54	$ 51
Wind Parks [Member] \| Consumers Energy Company [Member]
Asset Retirement Obligations [Line Items]
ARO Liability, at beginning of period	$ 6	3
Incurred		$ 3
Settled
Accretion
Cash flow Revisions
ARO Liability, end of period	$ 6	$ 6

Asset Retirement Obligations [Line Items]

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- Definition

The carrying amount of a liability for an asset retirement obligation. An asset retirement obligation is a legal obligation associated with the disposal or retirement of a tangible long-lived asset that results from the acquisition, construction or development, or the normal operations of a long-lived asset, except for certain obligations of lessees.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 410
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=6392692&loc=d3e7535-110849

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Asset Retirement Obligation
-URI http://asc.fasb.org/extlink&oid=6505190

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- Definition

Amount of accretion expense recognized during the period that is associated with an asset retirement obligation. Accretion expense measures and incorporates changes due to the passage of time into the carrying amount of the liability.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 410
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (c)(3)
-URI http://asc.fasb.org/extlink&oid=6392692&loc=d3e7535-110849

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 410
-SubTopic 20
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6392676&loc=d3e7480-110848

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Amount of asset retirement obligations incurred during the period.

+ References

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Amount of asset retirement obligations settled, or otherwise disposed of, during the period. This may include asset retirement obligations transferred to third parties associated with the sale of a long-lived asset.

+ References

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Amount of the Increase or Decrease in the amount of the asset retirement obligation during the current period for changes in the amount or timing of the estimated cash flows associated with the settlement of the obligation.

+ References

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