INCOME TAXES - COMPONENTS OF EARNINGS (LOSS) FROM CONTINUING OPERATIONS BEFORE INCOME TAXES, AFTER ADJUSTING EARNINGS (LOSS) FOR NON-CONTROLLING INTERESTS (Details) - USD ($) $ in Thousands	12 Months Ended
Sep. 30, 2025	Sep. 30, 2024
Income Tax Disclosure [Abstract]
United States	$ (5,980)	$ (1,360)
Canada	(1,064)	(2,532)
Total	$ (7,044)	$ (3,892)

Represents the portion of earnings (loss) from continuing operations before income taxes and after adjusting income (loss) for noncontrolling interests that is attributable to foreign operations, which is defined as Income or Loss generated from operations located outside the entity's country of domicile.

No definition available.

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Namespace Prefix:	brn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration