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Amount of deferred income tax expense (benefit) pertaining to income (loss) from continuing operations attributable to nonaccrual interest.

No definition available.

Name:	fmfg_DeferredIncomeTaxExpenseBenefitNonaccrualInterest
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Data Type:	xbrli:monetaryItemType
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Period Type:	duration

Amount of deferred income tax expense (benefit) pertaining to income (loss) from continuing operations attributable to other real estate owned allowance for loss.

No definition available.

Name:	fmfg_DeferredIncomeTaxExpenseBenefitOtherRealEstateOwnedAllowanceForLoss
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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Amount of deferred income tax expense (benefit) pertaining to income (loss) from continuing operations attributable to post-retirement benefits.

No definition available.

Name:	fmfg_DeferredIncomeTaxExpenseBenefitPostretirementBenefits
Namespace Prefix:	fmfg_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Amount of deferred income tax expense (benefit) pertaining to income (loss) from continuing operations attributable to prepaid captive insurance premium.

No definition available.

Name:	fmfg_DeferredIncomeTaxExpenseBenefitPrepaidCaptiveInsuarncePremium
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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Amount of deferred income tax expense (benefit) pertaining to income (loss) from continuing operations attributable to provision for loan losses.

No definition available.

Name:	fmfg_DeferredIncomeTaxExpenseBenefitProvisionForLoanLosses
Namespace Prefix:	fmfg_
Data Type:	xbrli:monetaryItemType
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Period Type:	duration

Amount of deferred income tax expense (benefit) pertaining to income (loss) from continuing operations attributable to write down of equity securities.

No definition available.

Name:	fmfg_DeferredIncomeTaxExpenseBenefitWriteDownOfEquitySecurities
Namespace Prefix:	fmfg_
Data Type:	xbrli:monetaryItemType
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Period Type:	duration

Amount of deferred income tax expense (benefit) pertaining to income (loss) from continuing operations.

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