RETIREMENT PLANS (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Sep. 30, 2025
Pension Plan
Net periodic benefit cost:
Interest cost	$ 102	$ 98
Expected return on plan assets	(230)	(200)
Amortization of net actuarial gain	0	0
Net periodic benefit (income) cost	(128)	(102)
Other disclosures
Estimated future contributions	$ 0
Number of Barnwell common stock held by the Pension Plan	676,296		666,077
SERP
Net periodic benefit cost:
Interest cost	$ 26	23
Expected return on plan assets	0	0
Amortization of net actuarial gain	0	0
Net periodic benefit (income) cost	26	$ 23
Other disclosures
Estimated future contributions	$ 270