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Amount of time deposits maturing in three years to fifth fiscal year following the latest fiscal year. Time deposits include, but are not limited to, certificates of deposits. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

No definition available.

Name:	bctf_TimeDepositMaturitiesYearThreeToYearFive
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Weighted average interest rate for time deposits held by the entity with maturity.

No definition available.

Name:	bctf_TimeDepositsWeightedAverageInterestRateMaturities
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Data Type:	num:percentItemType
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Period Type:	instant

Weighted average interest rate for time deposits held by the entity with maturities greater than one years, but three years or less.

No definition available.

Name:	bctf_TimeDepositsWeightedAverageInterestRateMaturitiesYearOneToYearThree
Namespace Prefix:	bctf_
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Weighted average interest rate for time deposits held by the entity with maturities greater than three years, but five years or less.

No definition available.

Name:	bctf_TimeDepositsWeightedAverageInterestRateMaturitiesYearThreeToYearFive
Namespace Prefix:	bctf_
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- References

No definition available.

Name:	us-gaap_BankingAndThriftAbstract
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Amount of time deposits maturing after the fifth fiscal year following the latest fiscal year. Time deposits include, but are not limited to, certificates of deposits. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 10
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6802200&loc=d3e1835-112601

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Amount of time deposits maturing in the next fiscal year following the latest fiscal year. Time deposits include, but are not limited to, certificates of deposits. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

Name:	us-gaap_TimeDepositMaturitiesYearOne
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Data Type:	xbrli:monetaryItemType
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Amount of deposits that cannot be withdrawn before a set date without penalty or for which notice of withdrawal is required. Time deposits include, but are not limited to, certificates of deposits, individual retirement accounts and open accounts.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.12)
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Name:	us-gaap_TimeDeposits
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Weighted average interest rate for time deposits held by the entity with maturities greater than five years.

No definition available.

Name:	us-gaap_TimeDepositsWeightedAverageInterestRateMaturitiesGreaterThanFiveYears
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Data Type:	num:percentItemType
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Period Type:	instant

Weighted average interest rate for time deposits held by the entity with maturities of one year or less.

No definition available.