Name:	mfbi_EmployeeStockOptionPlanAbstract
Namespace Prefix:	mfbi_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Period over which the Employee Stock Option Plan (ESOP) loan is to be repaid, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

No definition available.

Name:	mfbi_EmployeeStockOptionPlanLoanRepaymentPeriod
Namespace Prefix:	mfbi_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Period over which shares are vested in the Employee Stock Option Plan (ESOP), in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

No definition available.

Name:	mfbi_EmployeeStockOptionPlanVestingPeriod
Namespace Prefix:	mfbi_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Number of shares of capital stock purchased by the Employee Stock Ownership Plan.

No definition available.

Name:	mfbi_EmployeeStockOwnershipPlanPurchaseOfSharesNumberOfShares
Namespace Prefix:	mfbi_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

The amount of plan compensation cost recognized during the period.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 718
-SubTopic 40
-Section 50
-Paragraph 1
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480489/718-40-50-1

Name:	us-gaap_EmployeeStockOwnershipPlanESOPCompensationExpense
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Fair value of unearned shares held by the employee stock ownership plan (ESOP).

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 718
-SubTopic 40
-Section 50
-Paragraph 1
-Subparagraph (e)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480489/718-40-50-1

Name:	us-gaap_EmployeeStockOwnershipPlanESOPDeferredSharesFairValue
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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

The shares or units in an ESOP trust that have been assigned to individual participant accounts based on a known formula. IRS rules require allocations to be nondiscriminatory generally based on compensation, length of service, or a combination of both. For any particular participant such shares or units may be vested, unvested, or partially vested.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 718
-SubTopic 40
-Section 50
-Paragraph 1
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480489/718-40-50-1

Name:	us-gaap_EmployeeStockOwnershipPlanESOPNumberOfAllocatedShares
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Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

The shares that, although not legally released, will be released by a future scheduled and committed debt service payment and will be allocated to employees for service rendered in the current accounting period. The ESOP documents typically define the period of service to which the shares relate. ESOP shares are released to compensate employees directly, to settle employer liabilities for other employee benefits, and to replace dividends on allocated shares that are used for debt service.

Name:	us-gaap_EmployeeStockOwnershipPlanESOPNumberOfCommittedToBeReleasedShares
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Data Type:	xbrli:sharesItemType
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Period Type:	instant

Shares contributed to the ESOP that have not yet been released, committed to be released, or allocated to participant accounts. Suspense shares generally collateralize ESOP debt.

Name:	us-gaap_EmployeeStockOwnershipPlanESOPNumberOfSuspenseShares
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

Weighted average purchase price of capital shares purchased through an employee stock ownership plan.

No definition available.

Name:	us-gaap_EmployeeStockOwnershipPlanESOPWeightedAveragePurchasePriceOfSharesPurchased
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:perShareItemType
Balance Type:	na
Period Type:	duration

The cash outflow to finance the entity's defined contribution plan to acquire shares of the entity. The plan initially holds the shares in a suspense account, which is collateral for the loan. As the plan makes payment on the debt, the shares are released from the suspense account and become available to be allocated to participant accounts.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482740/230-10-45-15

Monroe Federal Bancorp, Inc. 10-Q