Amount of financing receivable past due.

No definition available.

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- Definition

Maximum period from the origination date a loan receivables held-for-sale will be sold.

+ References

No definition available.

+ Details

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Balance Type:	na
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- Definition

The cash inflow resulting from the sale of loans excluding loans acquired which are classified as held-for-sale, including proceeds from loans sold through mortgage securitization.

+ References

No definition available.

+ Details

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Namespace Prefix:	abr_
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

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 310
-SubTopic 20
-Name Accounting Standards Codification
-Section 40
-Paragraph 7
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481628/310-20-40-7

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481990/310-10-45-2

+ Details

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

- Definition

Amortized cost excluding accrued interest, of financing receivable on nonaccrual status. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 16
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-16

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

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

- Details

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

- Details

Name:	us-gaap_LineOfCreditFacilityAxis=abr_PrivateLabelMember
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Balance Type:
Period Type:

Loans Held-for-Sale, Net - Narrative (Details) - USD ($)	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025	Dec. 31, 2025
Loans Held-for-Sale, Net
Sale of loans held-for-sale excluding acquired loans	$ 671,000,000.0	$ 730,900,000
Loans held-for-sale placed on non-accrual status	0		$ 0
Financial Asset, Equal to or Greater than 90 Days Past Due
Loans Held-for-Sale, Net
Loans held-for-sale that were 90 days or more past due	$ 0		$ 0
US Government Sponsored-Enterprise Insured Loans
Loans Held-for-Sale, Net
Period of loans held for sale sold	60 days
Private Label
Loans Held-for-Sale, Net
Period of loans held for sale sold	180 days