XML 49 R40.htm IDEA: XBRL DOCUMENT v3.23.1

Note 4 - Loans Receivable - Risk Categories of Loans By Class of Loans (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Dec. 31, 2022
Loans receivable	$ 1,235,320	$ 1,234,872
Real Estate Portfolio [Member] | One-to-Four Family Residential Real Estate [Member]
Loans receivable	21,475	23,133
Financing Receivable, current year	0
Financing Receivable, one year before	151
Financing Receivable, two years before	0
Financing Receivable, three years before	200
Financing Receivable, four years before	0
Financing Receivable, prior	16,323
Financing Receivable, revolving	4,801
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	5
Current period recoveries, revolving	0
Current period recoveries, total	5
Recoveries (charge-offs), net, current year	0
Recoveries (charge-offs), net, one year before	0
Recoveries (charge-offs), net, two year before	0
Recoveries (charge-offs), net, three years before	0
Recoveries (charge-offs), net, four years before	0
Recoveries (charge-offs), net, prior	5
Recoveries (charge-offs), net, revolving	0
Recoveries (charge-offs), net, total	5
Real Estate Portfolio [Member] | Multi-family Mortgage [Member]
Loans receivable	544,673	537,394
Financing Receivable, current year	20,500
Financing Receivable, one year before	217,091
Financing Receivable, two years before	125,506
Financing Receivable, three years before	63,839
Financing Receivable, four years before	23,907
Financing Receivable, prior	85,151
Financing Receivable, revolving	8,679
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	5
Current period recoveries, revolving	0
Current period recoveries, total	5
Recoveries (charge-offs), net, current year	0
Recoveries (charge-offs), net, one year before	0
Recoveries (charge-offs), net, two year before	0
Recoveries (charge-offs), net, three years before	0
Recoveries (charge-offs), net, four years before	0
Recoveries (charge-offs), net, prior	5
Recoveries (charge-offs), net, revolving	0
Recoveries (charge-offs), net, total	5
Real Estate Portfolio [Member] | Nonresidential Real Estate [Member]
Loans receivable	123,360	119,705
Financing Receivable, current year	8,759
Financing Receivable, one year before	55,610
Financing Receivable, two years before	23,864
Financing Receivable, three years before	8,660
Financing Receivable, four years before	10,171
Financing Receivable, prior	16,042
Financing Receivable, revolving	254
Commercial Portfolio Segment [Member]
Loans receivable	544,216	553,056
Financing Receivable, current year	24,241
Financing Receivable, one year before	232,978
Financing Receivable, two years before	102,466
Financing Receivable, three years before	67,124
Financing Receivable, four years before	9,408
Financing Receivable, prior	5,836
Financing Receivable, revolving	102,163
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	1
Current period recoveries, revolving	0
Current period recoveries, total	1
Recoveries (charge-offs), net, current year	0
Recoveries (charge-offs), net, one year before	(79)
Recoveries (charge-offs), net, two year before	0
Recoveries (charge-offs), net, three years before	0
Recoveries (charge-offs), net, four years before	0
Recoveries (charge-offs), net, prior	1
Recoveries (charge-offs), net, revolving	0
Recoveries (charge-offs), net, total	(78)
Current period gross charge-offs	0
Current period gross charge-offs	(79)
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	(79)
Consumer Portfolio Segment [Member]
Loans receivable	1,596	1,584
Financing Receivable, current year	84
Financing Receivable, one year before	134
Financing Receivable, two years before	247
Financing Receivable, three years before	160
Financing Receivable, four years before	335
Financing Receivable, prior	5
Financing Receivable, revolving	631
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
Recoveries (charge-offs), net, current year	0
Recoveries (charge-offs), net, one year before	0
Recoveries (charge-offs), net, two year 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	(21)
Recoveries (charge-offs), net, total	(21)
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	0
Current period gross charge-offs	(22)
Current period gross charge-offs	(22)
Pass [Member]
Loans receivable	1,190,779	1,198,984
Pass [Member] | Real Estate Portfolio [Member] | One-to-Four Family Residential Real Estate [Member]
Loans receivable	21,080	22,648
Financing Receivable, current year	0
Financing Receivable, one year before	151
Financing Receivable, two years before	0
Financing Receivable, three years before	200
Financing Receivable, four years before	0
Financing Receivable, prior	16,109
Financing Receivable, revolving	4,620
Pass [Member] | Real Estate Portfolio [Member] | Multi-family Mortgage [Member]
Loans receivable	541,885	534,253
Financing Receivable, current year	20,500
Financing Receivable, one year before	217,091
Financing Receivable, two years before	125,506
Financing Receivable, three years before	63,839
Financing Receivable, four years before	23,907
Financing Receivable, prior	82,363
Financing Receivable, revolving	8,679
Pass [Member] | Real Estate Portfolio [Member] | Nonresidential Real Estate [Member]
Loans receivable	120,351	116,635
Financing Receivable, current year	8,759
Financing Receivable, one year before	54,580
Financing Receivable, two years before	22,232
Financing Receivable, three years before	8,660
Financing Receivable, four years before	10,171
Financing Receivable, prior	15,695
Financing Receivable, revolving	254
Pass [Member] | Commercial Portfolio Segment [Member]
Loans receivable	505,882	523,889
Financing Receivable, current year	23,848
Financing Receivable, one year before	213,313
Financing Receivable, two years before	102,419
Financing Receivable, three years before	65,130
Financing Receivable, four years before	9,314
Financing Receivable, prior	5,771
Financing Receivable, revolving	86,087
Pass [Member] | Consumer Portfolio Segment [Member]
Loans receivable	1,581	1,559
Financing Receivable, current year	84
Financing Receivable, one year before	134
Financing Receivable, two years before	247
Financing Receivable, three years before	160
Financing Receivable, four years before	335
Financing Receivable, prior	5
Financing Receivable, revolving	616
Watch [Member]
Loans receivable	19,981	28,584
Watch [Member] | Real Estate Portfolio [Member] | One-to-Four Family Residential Real Estate [Member]
Loans receivable	44	62
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	44
Financing Receivable, revolving	0
Watch [Member] | Real Estate Portfolio [Member] | Multi-family Mortgage [Member]
Loans receivable	2,640	3,141
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	2,640
Financing Receivable, revolving	0
Watch [Member] | Real Estate Portfolio [Member] | Nonresidential Real Estate [Member]
Loans receivable	3,009	3,070
Financing Receivable, current year	0
Financing Receivable, one year before	1,030
Financing Receivable, two years before	1,632
Financing Receivable, three years before	0
Financing Receivable, four years before	0
Financing Receivable, prior	347
Financing Receivable, revolving	0
Watch [Member] | Commercial Portfolio Segment [Member]
Loans receivable	14,283	22,299
Financing Receivable, current year	393
Financing Receivable, one year before	121
Financing Receivable, two years before	43
Financing Receivable, three years before	1,648
Financing Receivable, four years before	33
Financing Receivable, prior	65
Financing Receivable, revolving	11,980
Watch [Member] | Consumer Portfolio Segment [Member]
Loans receivable	5	12
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	0
Financing Receivable, revolving	5
Special Mention [Member]
Loans receivable	11,419	1,525
Special Mention [Member] | Real Estate Portfolio [Member] | One-to-Four Family Residential Real Estate [Member]
Loans receivable	16	4
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	16
Financing Receivable, revolving	0
Special Mention [Member] | Real Estate Portfolio [Member] | Multi-family Mortgage [Member]
Loans receivable	0	0
Special Mention [Member] | Real Estate Portfolio [Member] | Nonresidential Real Estate [Member]
Loans receivable	0	0
Special Mention [Member] | Commercial Portfolio Segment [Member]
Loans receivable	11,398	1,517
Financing Receivable, current year	0
Financing Receivable, one year before	11,050
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	348
Special Mention [Member] | Consumer Portfolio Segment [Member]
Loans receivable	5	4
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	0
Financing Receivable, revolving	5
Substandard [Member]
Loans receivable	4,279	4,372
Substandard [Member] | Real Estate Portfolio [Member] | One-to-Four Family Residential Real Estate [Member]
Loans receivable	280	327
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	128
Financing Receivable, revolving	152
Substandard [Member] | Real Estate Portfolio [Member] | Multi-family Mortgage [Member]
Loans receivable	148	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	148
Financing Receivable, revolving	0
Substandard [Member] | Real Estate Portfolio [Member] | Nonresidential Real Estate [Member]
Loans receivable	0	0
Substandard [Member] | Commercial Portfolio Segment [Member]
Loans receivable	3,846	4,041
Financing Receivable, current year	0
Financing Receivable, one year before	0
Financing Receivable, two years before	0
Financing Receivable, three years before	40
Financing Receivable, four years before	58
Financing Receivable, prior	0
Financing Receivable, revolving	3,748
Substandard [Member] | Consumer Portfolio Segment [Member]
Loans receivable	5	4
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	0
Financing Receivable, revolving	5
Substandard Nonaccrual [Member]
Loans receivable	8,862	1,407
Substandard Nonaccrual [Member] | Real Estate Portfolio [Member] | One-to-Four Family Residential Real Estate [Member]
Loans receivable	55	92
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	26
Financing Receivable, revolving	29
Substandard Nonaccrual [Member] | Real Estate Portfolio [Member] | Multi-family Mortgage [Member]
Loans receivable	0	0
Substandard Nonaccrual [Member] | Real Estate Portfolio [Member] | Nonresidential Real Estate [Member]
Loans receivable	0	0
Substandard Nonaccrual [Member] | Commercial Portfolio Segment [Member]
Loans receivable	8,807	1,310
Financing Receivable, current year	0
Financing Receivable, one year before	8,494
Financing Receivable, two years before	4
Financing Receivable, three years before	306
Financing Receivable, four years before	3
Financing Receivable, prior	0
Financing Receivable, revolving	0
Substandard Nonaccrual [Member] | Consumer Portfolio Segment [Member]
Loans receivable	$ 0	$ 5

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/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 2: 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 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//1943274/2147479853/942-210-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=bfin_WatchMember
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: