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Retirement Benefits (Schedule Of Net Loss And Prior Service Cost (Credit) That Will Be Amortized In Next Fiscal Year) (Details) $ in Millions | 12 Months Ended
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Dec. 31, 2018 USD ($)
DB Pension Plans |
Defined Benefit Plan Disclosure [Line Items] |
Regulatory asset | $ 47
AOCI | 3
DB Pension Plans | Consumers Energy Company |
Defined Benefit Plan Disclosure [Line Items] |
Regulatory asset | 47
OPEB Plan |
Defined Benefit Plan Disclosure [Line Items] |
Regulatory asset | (35)
AOCI | (1)
OPEB Plan | Consumers Energy Company |
Defined Benefit Plan Disclosure [Line Items] |
Regulatory asset | $ (35)

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- Definition Amount of cost (credit) included in accumulated other comprehensive (income) loss expected to be recognized in net periodic benefit cost (credit) for fiscal year following most recent annual statement of financial position. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (s) -URI http://asc.fasb.org/extlink&oid=108410482&loc=d3e1928-114920 + Details
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