CONSOLIDATED STATEMENTS OF COMPREHENSIVE (LOSS) INCOME - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Statement of Comprehensive Income [Abstract]
Net loss	$ (4,677)	$ (12,417)
Other comprehensive income (loss):
Foreign currency translation adjustments, net of taxes of $0	(146)	(234)
Retirement plans:
Amortization of accumulated other comprehensive loss into net periodic benefit cost, net of taxes of $0	120	55
Net actuarial loss arising during the period, net of taxes of $0	(218)	(2,224)
Curtailment gain, net of taxes of $0	1,726	0
Total other comprehensive income (loss)	1,482	(2,403)
Total comprehensive loss	(3,195)	(14,820)
Less: Comprehensive income (loss) attributable to non-controlling interests	79	(3)
Comprehensive loss attributable to Barnwell Industries, Inc.	$ (3,274)	$ (14,817)