XML 49 R39.htm IDEA: XBRL DOCUMENT v3.24.3

Note 4 - Loans Receivable - Risk Categories of Loans By Class of Loans (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2024	Dec. 31, 2023
Loans receivable	$ 931,838	$ 1,059,106
Real Estate Portfolio [Member] | One-to-Four Family Residential Real Estate [Member]
Loans receivable	15,634	18,945
Financing Receivable, current year	0	489
Financing Receivable, one year before	486	0
Financing Receivable, two years before	0	0
Financing Receivable, three years before	0	130
Financing Receivable, four years before	58	0
Financing Receivable, prior	11,834	14,356
Financing Receivable, revolving	3,256	3,970
Current period recoveries, current year	0	0
Current period recoveries, one year before	0	0
Current period recoveries, two years before	0	0
Current period recoveries, three years before	0	0
Current period recoveries, four years before	0	0
Current period recoveries, prior	27	45
Current period recoveries, revolving	0	0
Current period recoveries, total	27	45
Current period gross charge-offs		0
Current period gross charge-offs		0
Current period gross charge-offs		0
Current period gross charge-offs		0
Current period gross charge-offs		0
Current period gross charge-offs		(1)
Current period gross charge-offs		0
Current period gross charge-offs		(1)
Recoveries (charge-offs), net, current year		0
Recoveries (charge-offs), net, one year before		0
Recoveries (charge-offs), net, two years before		0
Recoveries (charge-offs), net, three years before		0
Recoveries (charge-offs), net, four years before		0
Recoveries (charge-offs), net, prior		44
Recoveries (charge-offs), net, revolving		0
Recoveries (charge-offs), net, total		44
Real Estate Portfolio [Member] | Multi-family Mortgage [Member]
Loans receivable	524,340	527,460
Financing Receivable, current year	24,789	43,504
Financing Receivable, one year before	38,261	212,740
Financing Receivable, two years before	207,147	112,667
Financing Receivable, three years before	109,415	57,743
Financing Receivable, four years before	55,552	22,064
Financing Receivable, prior	83,066	70,007
Financing Receivable, revolving	6,110	8,735
Current period recoveries, current year	0	0
Current period recoveries, one year before	0	0
Current period recoveries, two years before	0	0
Current period recoveries, three years before	0	0
Current period recoveries, four years before	0	0
Current period recoveries, prior	16	20
Current period recoveries, revolving	0	0
Current period recoveries, total	16	20
Real Estate Portfolio [Member] | Nonresidential Real Estate [Member]
Loans receivable	109,799	118,016
Financing Receivable, current year	15,748
Financing Receivable, one year before	14,994
Financing Receivable, two years before	48,388
Financing Receivable, three years before	14,994
Financing Receivable, four years before	7,449
Financing Receivable, prior	7,412
Financing Receivable, revolving	814
Commercial Portfolio Segment [Member]
Loans receivable	280,218	393,321
Financing Receivable, current year	20,069	50,026
Financing Receivable, one year before	35,900	158,485
Financing Receivable, two years before	104,865	63,552
Financing Receivable, three years before	39,359	33,581
Financing Receivable, four years before	15,220	3,028
Financing Receivable, prior	1,133	1,379
Financing Receivable, revolving	63,672	83,270
Current period recoveries, current year	0	0
Current period recoveries, one year before	0	0
Current period recoveries, two years before	0	37
Current period recoveries, three years before	5	40
Current period recoveries, four years before	7	0
Current period recoveries, prior	0	0
Current period recoveries, revolving	0	0
Current period recoveries, total	12	77
Current period gross charge-offs	0	(20)
Current period gross charge-offs	(292)	(1,850)
Current period gross charge-offs	(127)	0
Current period gross charge-offs	(43)	(306)
Current period gross charge-offs	(437)	0
Current period gross charge-offs	0	0
Current period gross charge-offs	0	0
Current period gross charge-offs	(899)	(2,176)
Recoveries (charge-offs), net, current year	0	(20)
Recoveries (charge-offs), net, one year before	(292)	(1,850)
Recoveries (charge-offs), net, two years before	(127)	37
Recoveries (charge-offs), net, three years before	(38)	(266)
Recoveries (charge-offs), net, four years before	(430)	0
Recoveries (charge-offs), net, prior	0	0
Recoveries (charge-offs), net, revolving	0	0
Recoveries (charge-offs), net, total	(887)	(2,099)
Consumer Portfolio Segment [Member]
Loans receivable	1,847	1,364
Financing Receivable, current year	791	336
Financing Receivable, one year before	200	8
Financing Receivable, two years before	3	140
Financing Receivable, three years before	53	80
Financing Receivable, four years before	49	247
Financing Receivable, prior	38	0
Financing Receivable, revolving	713	553
Current period recoveries, current year		0
Current period recoveries, one year before		0
Current period recoveries, two years before		0
Current period recoveries, three years before		0
Current period recoveries, four years before		0
Current period recoveries, prior		0
Current period recoveries, revolving		1
Current period recoveries, total		1
Current period gross charge-offs	0	0
Current period gross charge-offs	0	0
Current period gross charge-offs	0	0
Current period gross charge-offs	0	0
Current period gross charge-offs	0	0
Current period gross charge-offs	0	0
Current period gross charge-offs	(37)	(52)
Current period gross charge-offs	(37)	(52)
Recoveries (charge-offs), net, current year		0
Recoveries (charge-offs), net, one year before		0
Recoveries (charge-offs), net, two years before		0
Recoveries (charge-offs), net, three years before		0
Recoveries (charge-offs), net, four years before		0
Recoveries (charge-offs), net, prior		0
Recoveries (charge-offs), net, revolving		(51)
Recoveries (charge-offs), net, total		(51)
Pass [Member]
Loans receivable	897,774	1,021,519
Pass [Member] | Real Estate Portfolio [Member] | One-to-Four Family Residential Real Estate [Member]
Loans receivable	15,436	18,636
Financing Receivable, current year	0	489
Financing Receivable, one year before	486	0
Financing Receivable, two years before	0	0
Financing Receivable, three years before	0	130
Financing Receivable, four years before	58	0
Financing Receivable, prior	11,790	14,213
Financing Receivable, revolving	3,102	3,804
Pass [Member] | Real Estate Portfolio [Member] | Multi-family Mortgage [Member]
Loans receivable	522,196	526,127
Financing Receivable, current year	24,789	43,386
Financing Receivable, one year before	38,045	211,525
Financing Receivable, two years before	205,905	112,667
Financing Receivable, three years before	109,415	57,743
Financing Receivable, four years before	55,552	22,064
Financing Receivable, prior	82,380	70,007
Financing Receivable, revolving	6,110	8,735
Pass [Member] | Real Estate Portfolio [Member] | Nonresidential Real Estate [Member]
Loans receivable	108,527	118,016
Financing Receivable, current year	15,299	17,618
Financing Receivable, one year before	14,994	53,256
Financing Receivable, two years before	47,565	21,939
Financing Receivable, three years before	14,994	7,787
Financing Receivable, four years before	7,449	9,024
Financing Receivable, prior	7,412	8,288
Financing Receivable, revolving	814	104
Pass [Member] | Commercial Portfolio Segment [Member]
Loans receivable	249,774	357,384
Financing Receivable, current year	20,069	50,015
Financing Receivable, one year before	35,761	137,615
Financing Receivable, two years before	85,127	63,028
Financing Receivable, three years before	39,359	33,004
Financing Receivable, four years before	14,519	3,028
Financing Receivable, prior	1,133	1,379
Financing Receivable, revolving	53,806	69,315
Pass [Member] | Consumer Portfolio Segment [Member]
Loans receivable	1,841	1,356
Financing Receivable, current year	791	336
Financing Receivable, one year before	200	8
Financing Receivable, two years before	3	140
Financing Receivable, three years before	53	80
Financing Receivable, four years before	49	247
Financing Receivable, prior	38	0
Financing Receivable, revolving	707	545
Special Mention [Member]
Loans receivable	5,731	11,925
Special Mention [Member] | Real Estate Portfolio [Member] | One-to-Four Family Residential Real Estate [Member]
Loans receivable	0	0
Special Mention [Member] | Real Estate Portfolio [Member] | Multi-family Mortgage [Member]
Loans receivable	0	1,333
Financing Receivable, current year		118
Financing Receivable, one year before		1,215
Financing Receivable, two years before		0
Financing Receivable, three years before		0
Financing Receivable, four years before		0
Financing Receivable, prior		0
Financing Receivable, revolving		0
Special Mention [Member] | Real Estate Portfolio [Member] | Nonresidential Real Estate [Member]
Loans receivable	430	0
Financing Receivable, current year	0
Financing Receivable, one year before	0
Financing Receivable, two years before	430
Financing Receivable, three years before	0
Financing Receivable, four years before	0
Financing Receivable, prior	0
Financing Receivable, revolving	0
Special Mention [Member] | Commercial Portfolio Segment [Member]
Loans receivable	5,298	10,587
Financing Receivable, current year	0	0
Financing Receivable, one year before	0	0
Financing Receivable, two years before	0	0
Financing Receivable, three years before	0	0
Financing Receivable, four years before	0	0
Financing Receivable, prior	0	0
Financing Receivable, revolving	5,298	10,587
Special Mention [Member] | Consumer Portfolio Segment [Member]
Loans receivable	3	5
Financing Receivable, current year	0	0
Financing Receivable, one year before	0	0
Financing Receivable, two years before	0	0
Financing Receivable, three years before	0	0
Financing Receivable, four years before	0	0
Financing Receivable, prior	0	0
Financing Receivable, revolving	3	5
Substandard [Member]
Loans receivable	6,002	4,331
Substandard [Member] | Real Estate Portfolio [Member] | One-to-Four Family Residential Real Estate [Member]
Loans receivable	164	272
Financing Receivable, current year	0	0
Financing Receivable, one year before	0	0
Financing Receivable, two years before	0	0
Financing Receivable, three years before	0	0
Financing Receivable, four years before	0	0
Financing Receivable, prior	25	127
Financing Receivable, revolving	139	145
Substandard [Member] | Real Estate Portfolio [Member] | Multi-family Mortgage [Member]
Loans receivable	686	0
Financing Receivable, current year	0
Financing Receivable, one year before	0
Financing Receivable, two years before	0
Financing Receivable, three years before	0
Financing Receivable, four years before	0
Financing Receivable, prior	686
Financing Receivable, revolving	0
Substandard [Member] | Real Estate Portfolio [Member] | Nonresidential Real Estate [Member]
Loans receivable	449	0
Financing Receivable, current year	449
Financing Receivable, one year before	0
Financing Receivable, two years before	0
Financing Receivable, three years before	0
Financing Receivable, four years before	0
Financing Receivable, prior	0
Financing Receivable, revolving	0
Substandard [Member] | Commercial Portfolio Segment [Member]
Loans receivable	4,700	4,056
Financing Receivable, current year	0	0
Financing Receivable, one year before	0	666
Financing Receivable, two years before	119	0
Financing Receivable, three years before	0	22
Financing Receivable, four years before	13	0
Financing Receivable, prior	0	0
Financing Receivable, revolving	4,568	3,368
Substandard [Member] | Consumer Portfolio Segment [Member]
Loans receivable	3	3
Financing Receivable, current year	0	0
Financing Receivable, one year before	0	0
Financing Receivable, two years before	0	0
Financing Receivable, three years before	0	0
Financing Receivable, four years before	0	0
Financing Receivable, prior	0	0
Financing Receivable, revolving	3	3
Substandard Nonaccrual [Member]
Loans receivable	22,331	21,331
Substandard Nonaccrual [Member] | Real Estate Portfolio [Member] | One-to-Four Family Residential Real Estate [Member]
Loans receivable	34	37
Financing Receivable, current year	0	0
Financing Receivable, one year before	0	0
Financing Receivable, two years before	0	0
Financing Receivable, three years before	0	0
Financing Receivable, four years before	0	0
Financing Receivable, prior	19	16
Financing Receivable, revolving	15	21
Substandard Nonaccrual [Member] | Real Estate Portfolio [Member] | Multi-family Mortgage [Member]
Loans receivable	1,458	0
Financing Receivable, current year	0
Financing Receivable, one year before	216
Financing Receivable, two years before	1,242
Financing Receivable, three years before	0
Financing Receivable, four years before	0
Financing Receivable, prior	0
Financing Receivable, revolving	0
Substandard Nonaccrual [Member] | Real Estate Portfolio [Member] | Nonresidential Real Estate [Member]
Loans receivable	393	0
Financing Receivable, current year	0
Financing Receivable, one year before	0
Financing Receivable, two years before	393
Financing Receivable, three years before	0
Financing Receivable, four years before	0
Financing Receivable, prior	0
Financing Receivable, revolving	0
Substandard Nonaccrual [Member] | Commercial Portfolio Segment [Member]
Loans receivable	20,446	21,294
Financing Receivable, current year	0	11
Financing Receivable, one year before	139	20,204
Financing Receivable, two years before	19,619	524
Financing Receivable, three years before	0	555
Financing Receivable, four years before	688	0
Financing Receivable, prior	0	0
Financing Receivable, revolving	0	0
Substandard Nonaccrual [Member] | Consumer Portfolio Segment [Member]
Loans receivable	$ 0	$ 0

X

- Definition

Amount, excluding accrued interest, of decrease in allowance for credit loss on financing receivable from recovery (writeoff). Excludes net investment in lease.

+ References

No definition available.

+ Details

Name:	bfin_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossRecoveryWriteoffNet
Namespace Prefix:	bfin_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

X

- Definition

Amount, excluding accrued interest, of recovery of financing receivable originated more than five years before current fiscal year. Excludes net investment in lease.

+ References

No definition available.

+ Details

Name:	bfin_FinancingReceivableExcludingAccruedInterestOriginatedMoreThanFiveYearsBeforeCurrentFiscalYearRecovery
Namespace Prefix:	bfin_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

X

- Definition

Amount, excluding accrued interest, of recovery (writeoff) of financing receivable originated more than five years before current fiscal year. Excludes net investment in lease.

+ References

No definition available.

+ Details

Name:	bfin_FinancingReceivableExcludingAccruedInterestOriginatedMoreThanFiveYearsBeforeCurrentFiscalYearRecoveryWriteoffNet
Namespace Prefix:	bfin_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

X

- Definition

Amount, excluding accrued interest, of recovery of financing receivable that can be withdrawn, repaid, and redrawn.

+ References

No definition available.

+ Details

Name:	bfin_FinancingReceivableExcludingAccruedInterestRevolvingRecovery
Namespace Prefix:	bfin_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

X

- Definition

Amount, excluding accrued interest, of recovery (writeoff) of financing receivable that can be withdrawn, repaid, and redrawn.

+ References

No definition available.

+ Details

Name:	bfin_FinancingReceivableExcludingAccruedInterestRevolvingRecoveryWriteoffNet
Namespace Prefix:	bfin_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

X

- Definition

Amount, excluding accrued interest, of recovery of financing receivable originated four years before current fiscal year. Excludes net investment in lease.

+ References

No definition available.

+ Details

Name:	bfin_FinancingReceivableExcludingAccruedInterestYearFiveOriginatedFourYearsBeforeCurrentFiscalYearRecovery
Namespace Prefix:	bfin_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

X

- Definition

Amount, excluding accrued interest, of recovery (writeoff) of financing receivable originated four years before current fiscal year. Excludes net investment in lease.

+ References

No definition available.

+ Details

Name:	bfin_FinancingReceivableExcludingAccruedInterestYearFiveOriginatedFourYearsBeforeCurrentFiscalYearRecoveryWriteoffNet
Namespace Prefix:	bfin_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

X

- Definition

Amount, excluding accrued interest, of recovery of financing receivable originated three years before current fiscal year. Excludes net investment in lease.

+ References

No definition available.

+ Details

Name:	bfin_FinancingReceivableExcludingAccruedInterestYearFourOriginatedThreeYearsBeforeCurrentFiscalYearRecovery
Namespace Prefix:	bfin_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

X

- Definition

Amount, excluding accrued interest, of recovery (writeoff) of financing receivable originated three years before current fiscal year. Excludes net investment in lease.

+ References

No definition available.

+ Details

Name:	bfin_FinancingReceivableExcludingAccruedInterestYearFourOriginatedThreeYearsBeforeCurrentFiscalYearRecoveryWriteoffNet
Namespace Prefix:	bfin_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

X

- Definition

Amount, excluding accrued interest, of recovery of financing receivable originated in current fiscal year. Excludes net investment in lease.

+ References

No definition available.

+ Details

Name:	bfin_FinancingReceivableExcludingAccruedInterestYearOneOriginatedCurrentFiscalYearRecovery
Namespace Prefix:	bfin_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

X

- Definition

Amount, excluding accrued interest, of recovery (writeoff) of financing receivable originated in current fiscal year. Excludes net investment in lease.

+ References

No definition available.

+ Details

Name:	bfin_FinancingReceivableExcludingAccruedInterestYearOneOriginatedCurrentFiscalYearRecoveryWriteoffNet
Namespace Prefix:	bfin_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

X

- Definition

Amount, excluding accrued interest, of recovery of financing receivable originated two years before current fiscal year. Excludes net investment in lease.

+ References

No definition available.

+ Details

Name:	bfin_FinancingReceivableExcludingAccruedInterestYearThreeOriginatedTwoYearsBeforeCurrentFiscalYearRecovery
Namespace Prefix:	bfin_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

X

- Definition

Amount, excluding accrued interest, of recovery (writeoff) of financing receivable originated two years before current fiscal year. Excludes net investment in lease.

+ References

No definition available.

+ Details

Name:	bfin_FinancingReceivableExcludingAccruedInterestYearThreeOriginatedTwoYearsBeforeCurrentFiscalYearRecoveryWriteoffNet
Namespace Prefix:	bfin_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

X

- Definition

Amount, excluding accrued interest, of recovery of financing receivable originated in fiscal year before current fiscal year. Excludes net investment in lease.

+ References

No definition available.

+ Details

Name:	bfin_FinancingReceivableExcludingAccruedInterestYearTwoOriginatedFiscalYearBeforeCurrentFiscalYearRecovery
Namespace Prefix:	bfin_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

X

- Definition

Amount, excluding accrued interest, of recovery (writeoff) of financing receivable originated in fiscal year before current fiscal year. Excludes net investment in lease.

+ References

No definition available.

+ Details

Name:	bfin_FinancingReceivableExcludingAccruedInterestYearTwoOriginatedFiscalYearBeforeCurrentFiscalYearRecoveryWriteoffNet
Namespace Prefix:	bfin_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

X

- Definition

Amortized cost, before allowance for credit loss, fee, and loan in process, of financing receivable. Excludes financing receivable covered under loss sharing agreement and net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481990/310-10-45-2

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-5

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 942
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(7))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478546/942-210-S99-1

+ Details

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

X

- Definition

Amount, excluding accrued interest, of increase in allowance for credit loss on financing receivable from recovery. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (e)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-13

+ Details

Name:	us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossRecovery
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

X

- Definition

Amount, excluding accrued interest, of decrease in allowance for credit loss on financing receivable from writeoff. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-6

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-13

+ Details

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

X

- Definition

Amount, excluding accrued interest, of writeoff of financing receivable originated more than five years before current fiscal year. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-6

+ Details

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

X

- Definition

Amount, excluding accrued interest, of writeoff of financing receivable that can be withdrawn, repaid, and redrawn.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-6

+ Details

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

X

- Definition

Amount, excluding accrued interest, of writeoff of financing receivable originated four years before current fiscal year. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-6

+ Details

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

X

- Definition

Amount, excluding accrued interest, of writeoff of financing receivable originated three years before current fiscal year. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-6

+ Details

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

X

- Definition

Amount, excluding accrued interest, of writeoff of financing receivable originated in current fiscal year. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-6

+ Details

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

X

- Definition

Amount, excluding accrued interest, of writeoff of financing receivable originated two years before current fiscal year. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-6

+ Details

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

X

- Definition

Amount, excluding accrued interest, of writeoff of financing receivable originated in fiscal year before current fiscal year. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-6

+ Details

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

X

- Definition

Amortized cost of financing receivable originated more than five years prior to current fiscal year. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 79
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-79

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-6

+ Details

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

X

- Definition

Amortized cost of financing receivable originated four years prior to current fiscal year. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 79
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-79

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-6

+ Details

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

X

- Definition

Amortized cost of financing receivable originated in current fiscal year. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 79
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-79

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-6

+ Details

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

X

- Definition

Amortized cost of financing receivable originated in fiscal year prior to current fiscal year. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 79
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-79

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-6

+ Details

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

X

- Definition

Amortized cost of financing receivable originated three years prior to current fiscal year. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 79
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-79

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-6

+ Details

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

X

- Definition

Amortized cost of financing receivable originated two years prior to current fiscal year. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 79
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-79

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-6

+ Details

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

X

- Definition

Amortized cost of financing receivable that can be withdrawn, repaid, and redrawn.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 79
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-79

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-6

+ Details

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

X

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=bfin_RealEstatePortfolioMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=bfin_OnetoFourFamilyResidentialRealEstateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=bfin_MultifamilyMortgageMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=bfin_NonresidentialRealEstateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_CommercialPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_ConsumerPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_InternalCreditAssessmentAxis=us-gaap_PassMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_InternalCreditAssessmentAxis=us-gaap_SpecialMentionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_InternalCreditAssessmentAxis=us-gaap_SubstandardMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_InternalCreditAssessmentAxis=bfin_SubstandardNonaccrualMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: