Note 9 - Investing in Written Options (Details Textual)	2 Months Ended
Jun. 30, 2026 USD ($)
Average Notional Amount of Derivative Contracts	$ 165,163

Amount of average notional amount specified by the derivative contracts.

No definition available.

Name:	bita_AverageNotionalAmountOfDerivativeContracts
Namespace Prefix:	bita_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration