Allowance for loan and lease losses charge offs, net.

No definition available.

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Namespace Prefix:	bfin_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of recovery of loans and lease receivables which had previously been fully or partially written-off as bad debts.

+ References

+ Details

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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

+ Details

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- Definition

Amount of loans and leases that have been written off from both loan receivables and allowance reserve for credit loss.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
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-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.7(d))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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Period Type:	duration

- Definition

Amount of allowance to cover probable credit losses on loans and leases. Includes carryover of or adjustments to the allowance for loan losses in connection with business combinations. Excludes allowance for loans and leases covered under loss sharing agreements.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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Period Type:	instant

- Definition

Amount of expense related to estimated loss from loan and lease transactions.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
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Loans Receivable - Activity in the Allowance for Loan Losses (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance				$ 8,366				$ 8,127	$ 8,366	$ 8,127
Loans charged off									(518)	(503)
Recoveries									477	829
Net charge-off									41	(326)
Provision for (recovery of) loan losses	$ 403	$ (23)	$ 23	(258)	$ (72)	$ (225)	$ 49	$ 161	145	(87)
Ending balance	8,470				8,366				8,470	8,366
One-to-four family residential real estate loans [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance				850					850
Loans charged off									(231)	(318)
Recoveries									206	145
Ending balance	699				850				699	850
Multi-family mortgage loans [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance				3,849					3,849
Loans charged off									(35)	(10)
Recoveries									34	70
Ending balance	3,991				3,849				3,991	3,849
Nonresidential real estate loans [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Loans charged off									(93)	(165)
Recoveries									0	17
Construction and land loans [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance				32					32
Recoveries									2	0
Ending balance	4				32				4	32
Commercial loans [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance				1,357					1,357
Loans charged off									(140)	0
Recoveries									229	594
Ending balance	1,517				1,357				1,517	1,357
Commercial leases [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance				655					655
Recoveries									5	2
Ending balance	755				655				755	655
Consumer loans [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance				$ 18					18
Loans charged off									(19)	(10)
Recoveries									1	1
Ending balance	$ 28				$ 18				$ 28	$ 18