Note 4 - Deposits, Prepayments and Other Current Assets - Schedule of Deposits, Prepayments and Other Current Assets (Details) - USD ($) $ in Thousands	Jun. 30, 2026	Jun. 30, 2025
Deposits, Prepayments and Other Current Assets	$ 74	$ 143

Represents the amount of deposits, prepaid expenses and other assets classified as current.

No definition available.

Name:	bvc_DepositsPrepaidExpenseAndOtherAssetsCurrent
Namespace Prefix:	bvc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant