Financings and Capitalization (Preferred Stock of Subsidiary) (Details) - $ / shares	Dec. 31, 2019	Dec. 31, 2018
Debt and Equity Securities, FV-NI [Line Items]
Par value of preferred stock (in dollars per share)	$ 0.01
Preferred stock authorized (in shares)	10,000,000
Consumers Energy Company
Debt and Equity Securities, FV-NI [Line Items]
Par value of preferred stock (in dollars per share)	$ 4.50	$ 4.50
Preferred Stock $4.50 Series \| Consumers Energy Company
Debt and Equity Securities, FV-NI [Line Items]
Par value of preferred stock (in dollars per share)	100	100
Optional redemption price (in dollars per share)	$ 110	$ 110
Preferred stock authorized (in shares)	7,500,000	7,500,000
Number of shares outstanding (in shares)	373,148	373,148

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

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-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://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 5
-Subparagraph (a)
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
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-Topic 505
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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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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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