FAIR VALUE - Additional Information (Detail)	3 Months Ended
Mar. 31, 2023 USD ($)
Fair Value Disclosures [Abstract]
Fair value assets and liabilities transfer amount	$ 0

Fair value assets and liabilities transfers amount.

No definition available.

Name:	bsbk_FairValueAssetsAndLiabilitiesTransfersAmount
Namespace Prefix:	bsbk_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration