Name:	bctf_AvailableForSaleSecuritiesGreaterThan10OfStockholdersEquity
Namespace Prefix:	bctf_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Amount of loans and securities were pledged to secure FHLB advances and for other purposes required or permitted by law.

No definition available.

Name:	bctf_LoansAndSecuritiesPledgedToSecureFHLBAdvances
Namespace Prefix:	bctf_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Amount of loans and securities were pledged to secure public deposits for other purposes required or permitted by law.

No definition available.

Name:	bctf_LoansAndSecuritiesPledgedToSecurePublicDeposits
Namespace Prefix:	bctf_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

No definition available.

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

The amount by which the fair value of an investment in debt and equity securities categorized as Available-for-sale is less than the amortized cost basis or carrying amount of that investment at the balance sheet date and the decline in fair value is deemed to be other than temporary, before considering whether or not such amount is recognized in earnings or other comprehensive income.

No definition available.