REDUCTION OF CARRYING VALUE OF ASSETS (Details) (USD $)	12 Months Ended
Sep. 30, 2013	Sep. 30, 2012
Reduction of carrying value of assets
Reduction of carrying value of assets	$ 4,506,000	$ 6,647,000
Real estate held for sale
Reduction of carrying value of assets
Reduction of carrying value of assets	0	1,854,000
Number of homes entered into a contract to sell		1
Investment in joint ventures
Reduction of carrying value of assets
Reduction of carrying value of assets		1,754,000
Passive minority interests in various joint ventures (as a percent)	1.50%
Investment in lot acquisition rights - Mauka Lands
Reduction of carrying value of assets
Reduction of carrying value of assets		488,000
Number of lot acquisition rights owned	14
Oil and natural gas properties
Reduction of carrying value of assets
Reduction of carrying value of assets	$ 4,506,000	$ 2,551,000

Represents the number of residential lots which the entity has the right to acquire.

No definition available.

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- Definition

Represents the percentage of ownership of common stock or equity participation in the investee accounted for under the cost method of accounting.

+ References

No definition available.

+ Details

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- Definition

Represents the number of real estate properties entered into a contract to sell.

+ References

No definition available.

+ Details

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Namespace Prefix:	brn_
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Period Type:	duration

- Definition

Amount of write-down of assets recognized in the income statement. Includes, but is not limited to, losses from tangible assets, intangible assets and goodwill.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 360

-SubTopic 10

-Section 45

-Paragraph 4

-URI http://asc.fasb.org/extlink&oid=8077374&loc=d3e2420-110228

+ Details

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Balance Type:	debit
Period Type:	duration

- Details

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