Represents the contract purchase of the real estate investment property.

No definition available.

Name:	brt_RealEstateInvestmentPropertyContractPurchasePrice
Namespace Prefix:	brt_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

This element represents acquisition-related costs incurred in connection with real estate investments acquired other than through foreclosure which costs have been expensed during the period.

+ References

No definition available.

+ Details

Name:	brt_RealEstateOtherAcquisitionsCostsExpensed
Namespace Prefix:	brt_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=64930739&loc=d3e28878-108400

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28551-108399

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The number of units in a real estate property owned as of the balance sheet date.

+ References

No definition available.

+ Details

Name:	us-gaap_NumberOfUnitsInRealEstateProperty
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

The cash outflow associated with the investment in or advances to an entity in which the reporting entity shares control of the entity with another party or group.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 13
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3213-108585

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Percentage of the Variable Interest Entity's (VIE) voting interest owned by (or beneficial interest in) the reporting entity (directly or indirectly).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 50
-Paragraph 5A
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=77990344&loc=SL6759159-111685

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Details

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Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis=us-gaap_VariableInterestEntityPrimaryBeneficiaryMember
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Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_TypeOfArrangementAxis=brt_PropertyAcquisitionMember
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Data Type:	na
Balance Type:
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- Details

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=us-gaap_CorporateJointVentureMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=us-gaap_MortgagesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
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- Details

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ACQUISITIONS, DISPOSITIONS AND IMPAIRMENT CHARGES - Schedule of Subsequent Property Acquisitions (Details)		12 Months Ended
	Dec. 07, 2017 USD ($) property_unit	Sep. 30, 2017 USD ($) property_unit	Sep. 30, 2016 USD ($) property_unit	Sep. 30, 2015 USD ($)
Acquisitions
No. of Units \| property_unit		9,568
Property acquisition costs		$ 0	$ 3,852,000	$ 1,885,000
Multi-family residential \| Primary beneficiary \| Purchase of properties \| Joint ventures
Acquisitions
No. of Units \| property_unit		1,728	3,336
Purchase Price		$ 231,604,000	$ 318,680,000
Initial BRT Equity		54,146,000	73,895,000
Property acquisition costs		3,364,000	3,852,000
Mortgages \| Multi-family residential \| Primary beneficiary \| Purchase of properties \| Joint ventures
Acquisitions
Acquisition Mortgage Debt		$ 161,824,000	$ 238,212,000
Subsequent event \| Multi-family residential \| Primary beneficiary \| Purchase of properties \| Joint ventures \| Madison, AL
Acquisitions
No. of Units \| property_unit	204
Purchase Price	$ 18,420,000
Initial BRT Equity	$ 4,456,000
Ownership Percentage	80.00%
Property acquisition costs	$ 174,000
Subsequent event \| Mortgages \| Multi-family residential \| Primary beneficiary \| Purchase of properties \| Joint ventures \| Madison, AL
Acquisitions
Acquisition Mortgage Debt	$ 15,000,000