LOSS PER COMMON SHARE (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Numerator:
Net loss from continuing operations	$ (1,553)	$ (1,006)	$ (4,691)	$ (2,438)
Less: Net (loss) earnings attributable to non-controlling interests of continuing operations	(3)	12	(5)	236
Net loss from continuing operations attributable to Barnwell Industries, Inc.	(1,550)	(1,018)	(4,686)	(2,674)
Net (loss) earnings from discontinued operations	0	(228)	12	(1,008)
Net loss attributable to Barnwell Industries, Inc.	$ (1,550)	$ (1,246)	$ (4,674)	$ (3,682)
Denominator:
Basic weighted-average number of common shares outstanding	10,053,534	10,028,090	10,051,390	10,014,609
Effect of dilutive securities - common stock options and restricted stock units	0	0	0	0
Diluted weighted-average number of common shares outstanding	10,053,534	10,028,090	10,051,390	10,014,609
Basic and diluted loss per common share attributable to Barnwell Industries, Inc. stockholders:
Basic net loss per common share from continuing operations attributable to Barnwell Industries, Inc. stockholders (in dollars per share)	$ (0.15)	$ (0.10)	$ (0.47)	$ (0.27)
Diluted net loss per common share from continuing operations attributable to Barnwell Industries, Inc. stockholders (in dollars per share)	(0.15)	(0.10)	(0.47)	(0.27)
Basic net loss per common share from discontinued operations (in dollars per share)	0	(0.02)	0	(0.10)
Diluted net loss per common share from discontinued operations (in dollars per share)	0	(0.02)	0	(0.10)
Basic net loss per common share attributable to Barnwell Industries, Inc. stockholders (in dollars per share)	(0.15)	(0.12)	(0.47)	(0.37)
Diluted net loss per common share attributable to Barnwell Industries, Inc. stockholders (in dollars per share)	$ (0.15)	$ (0.12)	$ (0.47)	$ (0.37)
Options
Antidilutive shares excluded from the computation of diluted shares
Antidilutive shares excluded from computation of loss per share (in shares)	465,000	465,000	465,000	465,000
Restricted Stock Units (RSUs)
Antidilutive shares excluded from the computation of diluted shares
Antidilutive shares excluded from computation of loss per share (in shares)	214,270	106,006	229,740	86,190