Name:	abr_InvestmentInHoldingCompanyOfDebtors
Namespace Prefix:	abr_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Value of LIBOR Floor Certificate transfers.

No definition available.

Name:	abr_LossContingencyLiborFloorCertificateTransfersValue
Namespace Prefix:	abr_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Represents the number of counts dismissed against defendant entities.

No definition available.

Name:	abr_LossContingencyNumberOfCountsDismissedAgainstDefendantEntities
Namespace Prefix:	abr_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

Represents related to the Company number of defendants related to the entity.

No definition available.

Name:	abr_LossContingencyNumberOfDefendantsRelatedToCompany
Namespace Prefix:	abr_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

Represents the number of defendants removed due to consolidation of lawsuits.

No definition available.

Name:	abr_LossContingencyNumberOfDefendantsRemovedDueToConsolidationOfLawsuits
Namespace Prefix:	abr_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

Number of defendants named in a legal action who are corporate and partnership entities.

No definition available.

Name:	abr_LossContingencyNumberOfDefendantsWhoAreCorporateAndPartnershipEntities
Namespace Prefix:	abr_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

Number of defendants named in a legal action who are individuals.

No definition available.

Name:	abr_LossContingencyNumberOfDefendantsWhoAreIndividuals
Namespace Prefix:	abr_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

Represents the number of lawsuits consolidated.

No definition available.

Name:	abr_LossContingencyNumberOfLawsuitConsolidated
Namespace Prefix:	abr_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

Represents the number of lawsuits after amendment.

No definition available.

Name:	abr_LossContingencyNumberOfLawsuitsAfterConsolidationOfLawsuit
Namespace Prefix:	abr_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

Represents the number of lawsuits before amendment.

No definition available.

Name:	abr_LossContingencyNumberOfLawsuitsBeforeConsolidationOfLawsuit
Namespace Prefix:	abr_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

The total number of new claims filed pertaining to a loss contingency in the United states Bankruptcy Court during the period.

No definition available.

Name:	abr_LossContingencyNumberOfNewClaimsFiledInUnitedStatesBankruptcyCourt
Namespace Prefix:	abr_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

Represents the number of defendants remaining due to consolidation of lawsuits.

No definition available.

Name:	abr_LossContingencyNumberOfRemainingDefendantsDueToConsolidationOfLawsuits
Namespace Prefix:	abr_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

Represents the aggregate amount which the Trust would be seeking from the affiliates of the entity If the amended complaint is filed.

No definition available.

Name:	abr_LossContingencySeekingOfAmountsFromAffiliatesOfEntity
Namespace Prefix:	abr_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

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

Amount of loss contingency liability.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 1
-URI https://asc.fasb.org/extlink&oid=121557415&loc=d3e14326-108349

Reference 2: http://www.xbrl.org/2003/role/recommendedDisclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 10
-URI https://asc.fasb.org/extlink&oid=121557415&loc=d3e14615-108349

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

Number of claims dismissed.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 9
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=121557415&loc=d3e14557-108349

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=121557415&loc=d3e14435-108349

Name:	us-gaap_LossContingencyClaimsDismissedNumber
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

The total number of new claims filed pertaining to a loss contingency during the period.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=121557415&loc=d3e14435-108349

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 9
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=121557415&loc=d3e14557-108349

Name:	us-gaap_LossContingencyNewClaimsFiledNumber
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

Number of defendants named in a legal action.

Name:	us-gaap_LossContingencyNumberOfDefendants
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

Name:	dei_LegalEntityAxis=abr_ArborESHIILLCMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	srt_LitigationCaseAxis=abr_LawsuitFiledByExtendedStayLitigationTrustMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_LossContingenciesByNatureOfContingencyAxis=abr_FiduciaryDutyClaimsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: