Contingencies and Commitments (Summary of Guarantees) (Details) $ in Millions	Mar. 31, 2025 USD ($)
Variable Interest Entity, Primary Beneficiary \| Aviator Wind Equity Holdings
Guarantees And Other Contingencies [Line Items]
Ownership percentage	49.00%
Guarantees
Guarantees And Other Contingencies [Line Items]
Maximum Obligation	$ 30
Carrying Amount	0
Guarantees \| Consumers Energy Company
Guarantees And Other Contingencies [Line Items]
Maximum Obligation	30
Carrying Amount	0
Indemnity obligations from sale of membership interests in VIEs
Guarantees And Other Contingencies [Line Items]
Maximum Obligation	251
Carrying Amount	0
Indemnity obligations from stock and asset sale agreements
Guarantees And Other Contingencies [Line Items]
Maximum Obligation	153
Carrying Amount	$ 1

Guarantees And Other Contingencies [Line Items]

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- Definition

The current carrying amount of the liability for the freestanding or embedded guarantor's obligations under the guarantee or each group of similar guarantees.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 460
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482425/460-10-50-4

+ Details

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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://www.xbrl.org/2003/role/disclosureRef
-Topic 460
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Subparagraph (b)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482425/460-10-50-4

+ Details

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- Definition

The equity interest of noncontrolling shareholders, partners or other equity holders in consolidated entity.

+ References

No definition available.

+ Details

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