New Accounting Standards (Details) - USD ($) $ in Millions	9 Months Ended
Sep. 30, 2016	Dec. 31, 2015
Unamortized debt issuance costs	$ 44	$ 41
New Accounting Pronouncement, Early Adoption, Effect [Member]
Excess tax benefit related to stock	7
Retained Earnings (Accumulated Deficit) [Member]
Cumulative effect of change in accounting principle	33
Consumers Energy Company [Member]
Unamortized debt issuance costs	25	$ 23
Consumers Energy Company [Member] \| New Accounting Pronouncement, Early Adoption, Effect [Member]
Excess tax benefit related to stock	$ 7

Amount after tax of increase (decrease) to equity or (increase) decrease to net assets, resulting from the cumulative effect adjustment of a new accounting principle applied in the period of adoption.

No definition available.

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- Definition

Amount, after accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28555-108399

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.17)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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- Definition

The total recognized tax benefit related to compensation cost for equity-based payment arrangements recognized in income during the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (h)(1)(i)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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