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

Amount of purchases of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

No definition available.

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

Amount of recoveries of financial instrument measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

No definition available.

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

Amount of sale of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

No definition available.

Name:	fmfg_FairValueMeasurementWithUnobservableInputsReconciliationNonrecurringBasisAssetSales
Namespace Prefix:	fmfg_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Amount of settlement of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

No definition available.

Name:	fmfg_FairValueMeasurementWithUnobservableInputsReconciliationNonrecurringBasisAssetSettlements
Namespace Prefix:	fmfg_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Fair value of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

No definition available.

Name:	fmfg_FairValueMeasurementWithUnobservableInputsReconciliationNonrecurringBasisAssetValue
Namespace Prefix:	fmfg_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Amount of gain (loss) recognized in the income statement for financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

No definition available.