Financings and Capitalization (Preferred Stock of Subsidiary) (Details) (USD $) In Millions, except Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Schedule of Trading Securities and Other Trading Assets [Line Items]
Par value of Preferred Stock	$ 0.01
Shares of Preferred Stock authorized	10,000,000us-gaap_PreferredStockSharesAuthorized
Consumers Energy Company [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Par value of Preferred Stock	$ 100	$ 100
Shares of Preferred Stock authorized	7,500,000	7,500,000
Preferred stock Value	$ 37	$ 37
Preferred Stock $4.50 Series [Member] \| Consumers Energy Company [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Optional Redemption Price	$ 110.00	$ 110.00
Number of Shares	373,148	373,148
Preferred stock Value	$ 37	$ 37

Face amount or stated value per share of preferred stock nonredeemable or redeemable solely at the option of the issuer.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

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-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.28)

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The price per share at which the preferred stock of an entity that has priority over common stock in the distribution of dividends and in the event of liquidation of the entity is redeemed or may be called at. The redemption features of this preferred stock are solely within the control of the issuer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section 50

-Paragraph 3

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The maximum number of nonredeemable preferred shares (or preferred stock redeemable solely at the option of the issuer) permitted to be issued by an entity's charter and bylaws.

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Total number of nonredeemable preferred shares (or preferred stock redeemable solely at the option of the issuer) issued to shareholders (includes related preferred shares that were issued, repurchased, and remain in the treasury). May be all or portion of the number of preferred shares authorized. Excludes preferred shares that are classified as debt.

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Aggregate par or stated value of issued nonredeemable preferred stock (or preferred stock redeemable solely at the option of the issuer). This item includes treasury stock repurchased by the entity. Note: elements for number of nonredeemable preferred shares, par value and other disclosure concepts are in another section within stockholders' equity.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Article 3

Reference 2: http://www.xbrl.org/2003/role/presentationRef

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-Topic 505

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-Publisher FASB

-Name Accounting Standards Codification

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-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.28)

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