Trade and other payables - Additional Information (Detail) $ in Thousands	12 Months Ended
Jun. 30, 2025 USD ($)
Payables and Accruals [Line Items]
Payment of disputed trade payables and accrued clinical development project costs	$ 1,200
Payments for payables to vendor	495
Other Nonoperating Income (Expense) [Member]
Payables and Accruals [Line Items]
Liability settlement gain	$ 764

Payment of disputed trade payables and accrued clinical development project costs.

No definition available.

Name:	bntc_PaymentOfDisputedTradePayablesAndAccruedClinicalDevelopmentProjectCosts
Namespace Prefix:	bntc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration