Real Estate Loan (Details) - USD ($)	3 Months Ended
Dec. 31, 2016	Dec. 31, 2015	Sep. 30, 2016
Mortgage Loans on Real Estate [Line Items]
Collections from real estate loans	$ 13,600,000	$ 0
Real estate loan	5,900,000		$ 19,500,000
Stated rate			11.00%
RBHTRB Newark Holdings LLC \| Disposal Group, Disposed of by Sale, Not Discontinued Operations
Mortgage Loans on Real Estate [Line Items]
Collections from real estate loans	13,600,000
Proceeds from interest received	2,606,000
Real estate loan	$ 5,900,000		$ 19,500,000

Loan Receivable With Fixed Rates of Interest, Stated Rate

No definition available.

Name:	brt_LoanReceivableWithFixedRatesofInterestStatedRate
Namespace Prefix:	brt_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The balance represents the amount of loans that are secured by real estate mortgages, offset by the reserve to cover probable credit losses on the loan portfolio.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.1(c))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

+ Details

Name:	us-gaap_MortgageLoansOnRealEstateCommercialAndConsumerNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- 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

The cash inflow associated with the collection, including prepayments, of loans receivable issued for financing of goods and services.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 12
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3179-108585

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Investing Activities
-URI http://asc.fasb.org/extlink&oid=6516133

+ Details

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

- Definition

Interest received on loans and other debt instruments during the current period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 25
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3536-108585

+ Details

Name:	us-gaap_ProceedsFromInterestReceived
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

Name:	us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis=brt_RBHTRBNewarkHoldingsLLCMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: