RETIREMENT PLANS (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024	Sep. 30, 2024
Pension Plan
Net periodic benefit cost:
Interest cost	$ 98	$ 103	$ 293	$ 308
Expected return on plan assets	(200)	(192)	(600)	(575)
Amortization of net actuarial gain	0	0	0	0
Net periodic benefit (income) cost	(102)	(89)	(307)	(267)
Other disclosures
Estimated future contributions	$ 0		$ 0
Number of Barnwell common stock held by the Pension Plan	520,350		520,350		413,148
SERP
Net periodic benefit cost:
Interest cost	$ 24	24	$ 71	72
Expected return on plan assets	0	0	0	0
Amortization of net actuarial gain	0	(21)	0	(64)
Net periodic benefit (income) cost	24	$ 3	71	$ 8
Other disclosures
Estimated future contributions	$ 76		$ 76