Represents customer reserve related to factored receivables.

No definition available.

Name:	bfin_FactoredReceivableCustomerReserves
Namespace Prefix:	bfin_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Represents factored receivable unpaid principal balance.

+ References

No definition available.

+ Details

Name:	bfin_FactoredReceivableUnpaidPrincipalBalance
Namespace Prefix:	bfin_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of increase (decrease) in allowance for credit loss on financing receivable as a percentage.

+ References

No definition available.

+ Details

Name:	bfin_FinancingReceivableAllowanceForCreditLossPeriodIncreaseDecreasePercent
Namespace Prefix:	bfin_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount, after allocation of valuation allowances and deferred tax liability, of deferred tax asset attributable to deductible differences and carryforwards, without jurisdictional netting.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 2
-URI https://asc.fasb.org/extlink&oid=121826272&loc=d3e32537-109319

+ Details

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

- Definition

Amount of lessee's right to use underlying asset under operating lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 45
-Paragraph 1
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=123391704&loc=SL77918627-209977

+ Details

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

- Definition

Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

+ References

No definition available.

+ Details

Name:	us-gaap_PropertyPlantAndEquipmentUsefulLife
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_AdjustmentsForNewAccountingPronouncementsAxis=us-gaap_AccountingStandardsUpdate201602Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=us-gaap_BuildingAndBuildingImprovementsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=us-gaap_BuildingMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=us-gaap_FurnitureAndFixturesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=us-gaap_ComputerEquipmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=us-gaap_AutomobilesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Note 1 - Summary of Significant Accounting Policies (Details Textual) - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Jan. 01, 2019
Factored Receivable Unpaid Principal Balance	$ 7,000,000.0	$ 187,000
Factored Receivable, Customer Reserves	1,400,000	122,000
Deferred Tax Assets, Net, Total	$ 5,175,000	$ 2,762,000
Accounting Standards Update 2016-02 [Member]
Operating Lease, Right-of-Use Asset			$ 6,700,000
Minimum [Member]
Financing Receivable, Allowance for Credit Loss, Period Increase (Decrease), Percent	20.00%
Maximum [Member]
Financing Receivable, Allowance for Credit Loss, Period Increase (Decrease), Percent	25.00%
Building and Building Improvements [Member] \| Minimum [Member]
Property, Plant and Equipment, Useful Life (Year)	25 years
Building and Building Improvements [Member] \| Maximum [Member]
Property, Plant and Equipment, Useful Life (Year)	40 years
Building [Member] \| Minimum [Member]
Property, Plant and Equipment, Useful Life (Year)	10 years
Building [Member] \| Maximum [Member]
Property, Plant and Equipment, Useful Life (Year)	20 years
Furniture and Fixtures [Member] \| Minimum [Member]
Property, Plant and Equipment, Useful Life (Year)	5 years
Furniture and Fixtures [Member] \| Maximum [Member]
Property, Plant and Equipment, Useful Life (Year)	15 years
Computer Equipment [Member] \| Minimum [Member]
Property, Plant and Equipment, Useful Life (Year)	2 years
Computer Equipment [Member] \| Maximum [Member]
Property, Plant and Equipment, Useful Life (Year)	5 years
Automobiles [Member] \| Maximum [Member]
Property, Plant and Equipment, Useful Life (Year)	4 years