LOSS PER COMMON SHARE (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Net Earnings (Loss) (Numerator)
Basic	$ (4,756)	$ (12,414)
Diluted	$ (4,756)	$ (12,414)
Shares (Denominator)
Basic (in shares)	8,277,160	8,277,160
Effect of dilutive securities-common stock options (in shares)	0	0
Diluted (in shares)	8,277,160	8,277,160
Per-Share Amount
Basic net loss per common share attributable to Barnwell Industries, Inc. stockholders (in dollars per share)	$ (0.57)	$ (1.50)
Diluted net loss per common share attributable to Barnwell Industries, Inc. stockholders (in dollars per share)	$ (0.57)	$ (1.50)
Options
Antidilutive shares of common stock excluded from the computation of diluted shares
Antidilutive shares excluded from computation of earnings (loss) per share (in shares)	0	318,750