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Contingencies and Commitments (Guarantees) (Details) $ in Millions | 9 Months Ended
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Sep. 30, 2021 USD ($)
Variable Interest Entity, Primary Beneficiary | Aviator Wind Class B Membership |
Guarantees And Other Contingencies [Line Items] |
Ownership percentage | 49.00%
Guarantees |
Guarantees And Other Contingencies [Line Items] |
Expiration Date | indefinite
Maximum Obligation | $ 30
Carrying Amount | $ 0
Guarantees | Consumers Energy Company |
Guarantees And Other Contingencies [Line Items] |
Expiration Date | indefinite
Maximum Obligation | $ 30
Carrying Amount | $ 0
Indemnification Agreement From Purchase Of Variable Interest Entity |
Guarantees And Other Contingencies [Line Items] |
Expiration Date | indefinite
Maximum Obligation | $ 320
Carrying Amount | $ 0
Indemnity Obligations From Stock And Asset Sales Agreements |
Guarantees And Other Contingencies [Line Items] |
Expiration Date | indefinite
Maximum Obligation | $ 153
Carrying Amount | 2
Tax And Other Indemnity Obligations | Consumers Energy Company |
Guarantees And Other Contingencies [Line Items] |
Carrying Amount | $ 1

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- Definition Maximum potential amount of future payments (undiscounted) the guarantor could be required to make under the guarantee or each group of similar guarantees before reduction for potential recoveries under recourse or collateralization provisions. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 460 -SubTopic 10 -Section 50 -Paragraph 4 -Subparagraph (b)(1) -URI http://asc.fasb.org/extlink&oid=124440162&loc=d3e12069-110248 + Details
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