OIL AND NATURAL GAS PROPERTIES (Details) - USD ($)	1 Months Ended				12 Months Ended
	Sep. 30, 2015	May. 31, 2014	Apr. 30, 2014	Feb. 28, 2014	Sep. 30, 2015	Sep. 30, 2014	Aug. 27, 2015	Nov. 13, 2014
Oil and natural gas properties
Restricted cash	$ 7,458,000				$ 7,458,000	$ 0
Gain (loss) recognized from property sales						0
Liabilities associated with properties sold					2,013,000	718,000
Revenues					17,533,000	31,445,000
Net earnings (loss)					1,769,000	1,338,000
Net earnings (loss) attributable to Barnwell Industries, Inc. stockholders					$ 1,263,000	$ 672,000
Net earnings (loss) per common share attributable to Barnwell Industries, Inc. stockholders (in dollars per share)					$ 0.15	$ 0.08
Oil and natural gas properties
Oil and natural gas properties
Property and equipment							$ 397,000	$ 751,000
Asset retirement obligation							(91,000)	(225,000)
Net identifiable assets acquired							$ 306,000	$ 526,000
Proceeds from divestiture of businesses						$ 13,846,000
Oil and natural gas properties | Dunvegan and Belloy areas of Alberta
Oil and natural gas properties
Divestiture of businesses, sale price					$ 21,875,000
Proceeds from divestiture of businesses	$ 14,162,000
Period after closing of agreement for final determination of the customary adjustments to the purchase price	180 days
Restricted cash	$ 7,135,000				7,135,000
Percent difference in capitalized costs divided by proved reserves	220.00%
Gain (loss) recognized from property sales					6,217,000
Liabilities associated with properties sold					2,013,000
Revenues					17,533,000
Net earnings (loss)					1,769,000
Net earnings (loss) attributable to Barnwell Industries, Inc. stockholders					$ 1,263,000
Net earnings (loss) per common share attributable to Barnwell Industries, Inc. stockholders (in dollars per share)					$ 0.15
Oil and natural gas properties | Dunvegan and Belloy areas of Alberta | Pro Forma
Oil and natural gas properties
Revenues					$ 13,235,000
Net earnings (loss)					(761,000)
Net earnings (loss) attributable to Barnwell Industries, Inc. stockholders					$ (1,267,000)
Net earnings (loss) per common share attributable to Barnwell Industries, Inc. stockholders (in dollars per share)					$ (0.15)
Oil and natural gas properties | Dunvegan and Belloy areas of Alberta | Working Interest Owner
Oil and natural gas properties
Proceeds from divestiture of businesses	$ 7,247,000
Oil and natural gas properties | Chauvin, Cessford and Rat Creek areas of Alberta
Oil and natural gas properties
Proceeds from divestiture of businesses			$ 4,581,000
Oil and natural gas properties | Boundary Lake area of Alberta and British Columbia
Oil and natural gas properties
Proceeds from divestiture of businesses		$ 6,120,000
Oil leaseholds | Mantario area of Saskatchewan
Oil and natural gas properties
Proceeds from divestiture of businesses				$ 2,726,000
Miscellaneous oil and natural gas properties
Oil and natural gas properties
Proceeds from divestiture of businesses						$ 692,000