Loan Servicing (Details) - USD ($)	Sep. 30, 2020	Jun. 30, 2020
Loan Servicing
Unpaid principal balance of loans serviced for others	$ 5,860,783	$ 2,696,078
Custodial balances maintained by bank	$ 0	$ 0

Represents information related to unpaid principal balance of loans serviced for others.

No definition available.

Name:	tbba_UnpaidPrincipalBalanceOfLoansServicedForOthers
Namespace Prefix:	tbba_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant