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Amount of amortization for assets, excluding financial assets and goodwill, lacking physical substance with finite life expected to be recognized in the seventh fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

No definition available.

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Period Type:	instant

Amount of amortization for assets, excluding financial assets and goodwill, lacking physical substance with finite life expected to be recognized in the sixth fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

No definition available.

Name:	fmfg_FiniteLivedIntangibleAssetExpectedAmortizationYearSix
Namespace Prefix:	fmfg_
Data Type:	xbrli:monetaryItemType
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Period Type:	instant

Amount of amortization for assets, excluding financial assets and goodwill, lacking physical substance with finite life expected to be recognized in eighth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

No definition available.

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Data Type:	xbrli:monetaryItemType
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Period Type:	instant

Amount of amortization for assets, excluding financial assets and goodwill, lacking physical substance with finite life expected to be recognized in tenth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

No definition available.

Name:	fmfg_FinitelivedIntangibleAssetExpectedAmortizationYearTen
Namespace Prefix:	fmfg_
Data Type:	xbrli:monetaryItemType
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Useful life of finite-lived intangible asset, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Excludes goodwill and capitalized cost for software to be sold, leased, or marketed.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 350
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482665/350-30-50-5

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Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	instant

Amount of amortization expense for finite-lived intangible asset expected to be recognized in next fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach). Excludes goodwill and capitalized cost for software to be sold, leased, or marketed.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 350
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)(3)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482665/350-30-50-2

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Name Accounting Standards Codification
-Section 55
-Paragraph 40
-SubTopic 30
-Topic 350
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482640/350-30-55-40

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Amount of amortization expense for finite-lived intangible asset expected to be recognized in fifth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach). Excludes goodwill and capitalized cost for software to be sold, leased, or marketed.

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Period Type:	instant

Amount of amortization expense for finite-lived intangible asset expected to be recognized in fourth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach). Excludes goodwill and capitalized cost for software to be sold, leased, or marketed.

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Data Type:	xbrli:monetaryItemType
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Period Type:	instant

Amount of amortization expense for finite-lived intangible asset expected to be recognized in third fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach). Excludes goodwill and capitalized cost for software to be sold, leased, or marketed.

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Amount of amortization expense for finite-lived intangible asset expected to be recognized in second fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach). Excludes goodwill and capitalized cost for software to be sold, leased, or marketed.