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Retirement Benefits (Schedule of Net Periodic Benefit Cost Not yet Recognized) (Details) - USD ($) $ in Millions | Dec. 31, 2024 | Dec. 31, 2023
--- | --- | ---
Consumers Energy Company |  |
Regulatory assets |  |
Total regulatory assets | $ 3,798 | $ 3,886
DB Pension Plans and DB SERP |  |
Regulatory assets |  |
Net loss | 653 | 634
Prior service cost (credit) | 12 | 16
Total regulatory assets | 665 | 650
AOCI |  |
Net loss (gain) | 60 | 65
Prior service cost (credit) | 0 | 1
Total amounts recognized in regulatory assets and AOCI | 725 | 716
DB Pension Plans and DB SERP | Consumers Energy Company |  |
Regulatory assets |  |
Net loss | 653 | 634
Prior service cost (credit) | 12 | 16
Total regulatory assets | 665 | 650
AOCI |  |
Net loss (gain) | 15 | 20
Total amounts recognized in regulatory assets and AOCI | 680 | 670
OPEB Plan |  |
Regulatory assets |  |
Net loss | 176 | 191
Prior service cost (credit) | (94) | (100)
Total regulatory assets | 82 | 91
AOCI |  |
Net loss (gain) | (3) | (3)
Prior service cost (credit) | (2) | (2)
Total amounts recognized in regulatory assets and AOCI | 77 | 86
OPEB Plan | Consumers Energy Company |  |
Regulatory assets |  |
Net loss | 176 | 191
Prior service cost (credit) | (94) | (100)
Total regulatory assets | 82 | 91
AOCI |  |
Net loss (gain) | 0 | 0
Total amounts recognized in regulatory assets and AOCI | $ 82 | $ 91

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- Definition The pretax net amount of gains and losses that are not yet recognized as a component of net periodic benefit cost, and that are recognized as increases or decreases in regulatory assets (liabilities) as they arise. Gains and losses are due to changes in the value of either the benefit obligation or the plan assets resulting from experience different from that assumed or from a change in an actuarial assumption, or the consequence of a decision to temporarily deviate from the substantive plan. + References No definition available. + Details
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- Definition Amount related to the pretax cost of benefit changes attributable to plan participants' prior service pursuant to a plan amendment or a plan initiation, which has not yet been recognized as components of net periodic benefit cost. + References No definition available. + Details
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- Definition Total amount of regulatory assets (liabilities) and AOCI that have not been recognized as a component of net periodic cost. + References No definition available. + Details
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- Definition Amount, before tax, of accumulated other comprehensive income (loss) for gain (loss) of defined benefit plan, that has not been recognized in net periodic benefit (cost) credit. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 14A -Publisher FASB -URI https://asc.fasb.org/1943274/2147482790/220-10-45-14A Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (j) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480506/715-20-50-1 + Details
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- Definition Amount, before tax, of accumulated other comprehensive (income) loss for cost (credit) of benefit change attributable to participants' prior service from plan amendment or plan initiation of defined benefit plan, that has not been recognized in net periodic benefit cost (credit). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 14A -Publisher FASB -URI https://asc.fasb.org/1943274/2147482790/220-10-45-14A Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (j) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480506/715-20-50-1 + Details
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