Financings and Capitalization Financings and Capitalization (Debt Retirements) (Details) $ in Millions	9 Months Ended
Sep. 30, 2020 USD ($)
Debt Instrument [Line Items]
Redemption of debt	$ 725
Consumers Energy Company
Debt Instrument [Line Items]
Redemption of debt	725
Consumers Energy Company \| First Mortgage Bonds due October 2020
Debt Instrument [Line Items]
Redemption of debt	$ 100
Interest Rate	3.77%
Consumers Energy Company \| First Mortgage Bonds Due September 2022
Debt Instrument [Line Items]
Redemption of debt	$ 250
Interest Rate	5.30%
Consumers Energy Company \| First Mortgage Bonds Due May 2022
Debt Instrument [Line Items]
Redemption of debt	$ 375
Interest Rate	2.85%

Contractual interest rate for funds borrowed, under the debt agreement.

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 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

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+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3291-108585

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