Name:	abr_ContractualObligations
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Data Type:	xbrli:monetaryItemType
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Period Type:	duration

Loan Commitment Volume

No definition available.

Name:	abr_LoanCommitmentVolume
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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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- References

No definition available.

Name:	abr_LoanSalesDataAbstract
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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Amount of loans originated during the period.

No definition available.

Name:	abr_LoansOriginated
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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Amount of loans originated through loan payoffs and paydowns.

No definition available.

Name:	abr_LoansPayoffsAndPaydowns
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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Amount of new loans originated during the period

No definition available.

Name:	abr_NewLoansOriginated
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Data Type:	xbrli:monetaryItemType
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Represents the number of loans related to the real estate property under the loan portfolio.

No definition available.

Name:	abr_NumberOfLoansUnderSpecifiedLoanPortfolio
Namespace Prefix:	abr_
Data Type:	xbrli:integerItemType
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Period Type:	duration

Originated mortgage servicing rights rate, MSR income as a percent of loan commitments.

No definition available.

Name:	abr_OriginatedMortgageServicingRightsRate
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Data Type:	dtr-types:percentItemType
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Sale margin as a percent of loan sales.

No definition available.

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Data Type:	dtr-types:percentItemType
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The cash inflow from sales of loans that are secured with real estate mortgages and are held with the intention to resell in the near future.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 230
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 25
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482740/230-10-45-25

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 21
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482740/230-10-45-21

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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.

No definition available.

Name:	us-gaap_SegmentReportingInformationLineItems
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Data Type:	xbrli:stringItemType
Balance Type:	na
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Name:	us-gaap_StatementBusinessSegmentsAxis=abr_StructuredTransactionBusinessSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
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Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_BridgeLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=abr_MezzanineLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
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Name:	us-gaap_FinancialInstrumentAxis=srt_MultifamilyMember
Namespace Prefix:
Data Type:	na
Balance Type:
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Namespace Prefix:
Data Type:	na
Balance Type:
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Data Type:	na
Balance Type:
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Namespace Prefix:
Data Type:	na
Balance Type:
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Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

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

Name:	us-gaap_LineOfCreditFacilityAxis=abr_FederalHousingAdministrationLoansMember
Namespace Prefix:
Data Type:	na
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