Represents the percentage of gross loans receivable.

No definition available.

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Period Type:	instant

- 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

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+ Details

Name:	us-gaap_LoansAndLeasesReceivableAllowance
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount, before allowance and fees, of loans and leases receivable. Excludes loans and leases covered under loss sharing agreements.

+ References

+ Details

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Balance Type:	debit
Period Type:	instant

- Definition

Amount before allowance of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans and leases covered under loss sharing agreements.

+ References

+ Details

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

- Definition

Amount after allowance and deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements and loans held for sale.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of deferred fees paid by borrowers and unamortized costs incurred to originate loans and leases, unamortized loan commitments and loan syndication fees, and premiums over or discounts from face amounts of loans that are being amortized into income as an adjustment to yield. Excludes amounts for loans and leases covered under loss sharing agreements.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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Balance Type:	debit
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- Details

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Namespace Prefix:
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Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=bctf_OnetofourFamilyResidentialRealEstatePortfolioSegmentMember
Namespace Prefix:
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- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=bctf_CommercialAndIndustrialPortfolioSegmentMember
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Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=bctf_ConsumerAndOtherPortfolioSegmentMember
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Note 4 - Loans Held for Investment, Net - Components of Loans Held for Investment, Net (Details) - USD ($)	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017
Total, gross loans	$ 303,253,964			$ 286,840,889
Percentage of gross loans	100.00%			100.00%
Unamortized loan fees	$ (948,539)			$ (1,149,517)
Loans held for investment	302,305,425			285,691,372
Allowance for loan losses	(3,071,322)	$ (3,068,291)	$ (2,981,412)	(2,901,091)	$ (3,233,813)	$ (3,199,420)	$ (3,122,170)	$ (3,117,190)
Loans held for investment, net	299,234,103			282,790,281
Commercial Real Estate Portfolio Segment [Member]
Total, gross loans	$ 248,954,014			$ 233,102,637
Percentage of gross loans	82.10%			81.30%
Allowance for loan losses	$ (2,400,458)	(2,426,902)	(2,341,297)	$ (2,130,124)	(2,251,429)	(2,143,311)	(2,066,285)	(2,055,911)
One-to-four Family Residential Real Estate Portfolio Segment [Member]
Total, gross loans	$ 29,055,811			$ 29,855,462
Percentage of gross loans	9.60%			10.40%
Allowance for loan losses	$ (178,708)	(219,630)	(220,139)	$ (359,705)	(380,114)	(487,380)	(503,295)	(567,290)
Commercial and Industrial Portfolio Segment [Member]
Total, gross loans	$ 20,131,619			$ 17,508,258
Percentage of gross loans	6.60%			6.10%
Allowance for loan losses	$ (463,141)	(398,339)	(388,425)	$ (377,180)	(559,494)	(527,445)	(514,307)	(462,406)
Consumer and Other Portfolio Segment [Member]
Total, gross loans	$ 5,112,520			$ 6,374,532
Percentage of gross loans	1.70%			2.20%
Allowance for loan losses	$ (29,015)	$ (23,420)	$ (31,551)	$ (34,082)	$ (42,776)	$ (41,284)	$ (38,283)	$ (31,583)