Name:	abr_AllowanceForLoanAndLeaseLossesNetChargeOffsRatio
Namespace Prefix:	abr_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	duration

Reflects the total amount of loans and leases that have been removed or charged-off, from both loan receivables and the reserve for credit losses.

No definition available.

Name:	abr_AllowanceForLoanAndLeaseLossesTotalChargeOffs
Namespace Prefix:	abr_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Reflects the total amount of loans and leases that have been removed or charged-off, from both loan receivables and the reserve for credit losses, net of total recoveries for the period.

No definition available.

Name:	abr_AllowanceForLoanAndLeaseLossesTotalChargeOffsNetRecoveries
Namespace Prefix:	abr_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

The carrying value of impaired financing receivables derived after deducting unearned revenue and other holdbacks.

No definition available.

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

Amount of recovery of loans and lease receivables which had previously been fully or partially written-off as bad debts.

No definition available.

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

Amount of allowance for credit losses related to recorded investment.

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

Amount of average investment of impaired financing receivables for which there is a related allowance for credit losses.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 15

-Subparagraph (c)(1)

-URI http://asc.fasb.org/extlink&oid=28368275&loc=d3e5212-111524

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 17

-URI http://asc.fasb.org/extlink&oid=28368275&loc=d3e5258-111524

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

Amount of interest income, recognized on accrual basis, on financing receivables, for which there is a related allowance for credit losses and are recognized as impaired.

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

Unpaid principal balance of impaired financing receivables for which there is a related allowance for credit losses.