Note 4 - Loans Held for Investment, Net (Details Textual) - USD ($)	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016
Financing Receivable, Recorded Investment, Nonaccrual Status	$ 5,436,972	$ 5,968,221
Impaired Financing Receivable, Interest Income, Accrual Method	0	0
Financing Receivable, Modifications, Recorded Investment	$ 0	$ 0
Veterans Administration Loan [Member]
Number of Receivable Commitments Outstanding	0	0
Real Estate [Member]
Financing Receivable, Recorded Investment, Nonaccrual Status	$ 4,600,000	$ 3,600,000
Nonaccrual Loan Secure Percentage	84.50%	66.00%
Commercial Real Estate Portfolio Segment [Member]
Loans Receivable, Gross, Commercial, Construction	$ 14,700,000	$ 7,900,000
Financing Receivable, Recorded Investment, Nonaccrual Status	$ 3,483,078	$ 3,718,686

It represents the percentage of nonaccrual loans secured.

No definition available.

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Namespace Prefix:	bctf_
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- Definition

The number of receivable commitments outstanding.

+ References

No definition available.

+ Details

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- Definition

The amount of the outstanding recorded investment related to financing receivables that have been modified by troubled debt restructurings.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 40
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=82895541&loc=d3e18845-111554

+ Details

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- Definition

Recorded investment in financing receivables that are on nonaccrual status as of the balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 7
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5111-111524

+ Details

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- Definition

Amount of interest income recognized that the financing receivables (with related allowance for credit losses and without a related allowance for credit losses) were impaired.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 15
-Subparagraph (c)(2)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5212-111524

+ Details

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Period Type:	duration

- Definition

Amount before allowance of commercial construction loans. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans covered under loss sharing agreements.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5066-111524

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.7(a)(2))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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- Details

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- Details

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- Details

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