Equity Investments Made By Officers, Construction Project

No definition available.

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

- Definition

Equity Investments Made By Related Parties

+ References

No definition available.

+ Details

Name:	abr_EquityInvestmentsMadeByRelatedParties
Namespace Prefix:	abr_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Financing Receivable, Length Of Extension Period

+ References

No definition available.

+ Details

Name:	abr_FinancingReceivableLengthOfExtensionPeriod
Namespace Prefix:	abr_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Minimum variable interest rate for loans receivable.

+ References

No definition available.

+ Details

Name:	abr_LoansReceivableFloorInterestRate
Namespace Prefix:	abr_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the fixed interest rate on the mortgage loan receivable or the weighted average interest rate on a group of loans.

+ References

No definition available.

+ Details

Name:	abr_MortgageLoansOnRealEstateFixedInterestRate
Namespace Prefix:	abr_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of Officers

+ References

No definition available.

+ Details

Name:	abr_NumberOfOfficers
Namespace Prefix:	abr_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Represents the cash outflow during the reporting period in respect of payments for loans and investments funded and purchased by the reporting entity.

+ References

No definition available.

+ Details

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

- Definition

The percentage of equity participation interest.

+ References

No definition available.

+ Details

Name:	abr_PercentageOfEquityParticipationInterest
Namespace Prefix:	abr_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The minimum amount the entity agreed to fund under the related party commitment.

+ References

No definition available.

+ Details

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

- Definition

Represents the percentage of ownership of common stock or equity participation owned by related party.

+ References

No definition available.

+ Details

Name:	abr_RelatedPartyOwnershipPercentage
Namespace Prefix:	abr_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of contractual principal due at origination of mortgage loan within investment in mortgage loan on real estate by entity with substantial portion of business acquiring and holding investment real estate or interest in real estate.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name Regulation S-X (SX)
-Number 210
-Section 12
-Subsection 29
-Paragraph Column F
-Publisher SEC

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 948
-SubTopic 310
-Name Accounting Standards Codification
-Section S50
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478322/948-310-S50-2

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 948
-SubTopic 310
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.12-29(Column F))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479628/948-310-S99-1

+ Details

Name:	srt_MortgageLoansOnRealEstateFaceAmountOfMortgages
Namespace Prefix:	srt_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of operating interest income, including, but not limited to, amortization and accretion of premiums and discounts on securities.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 946
-SubTopic 830
-Name Accounting Standards Codification
-Section 55
-Paragraph 10
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479168/946-830-55-10

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 942
-SubTopic 310
-Name Accounting Standards Codification
-Section S50
-Paragraph 4
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479255/942-310-S50-4

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 942
-SubTopic 310
-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Subparagraph (SAB Topic 11.H.2.Q1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478116/942-310-S99-2

Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 220
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(1)(e))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483621/220-10-S99-2

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 22
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-22

Reference 6: http://www.xbrl.org/2003/role/exampleRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 48
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482785/280-10-55-48

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 320
-Name Accounting Standards Codification
-Section S99
-Paragraph 6
-Subparagraph (SX 210.12-14(Column E)(1))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477271/946-320-S99-6

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 320
-Name Accounting Standards Codification
-Section S99
-Paragraph 6
-Subparagraph (SX 210.12-14(Column E)(Footnote 4))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477271/946-320-S99-6

Reference 9: http://www.xbrl.org/2003/role/exampleRef
-Topic 946
-SubTopic 830
-Name Accounting Standards Codification
-Section 45
-Paragraph 39
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477346/946-830-45-39

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6-07(1)(b))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479134/946-220-S99-1

Reference 11: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 946
-SubTopic 320
-Name Accounting Standards Codification
-Section S99
-Paragraph 6
-Subparagraph (SX 210.12-14(Column E)(Footnote 6)(a))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477271/946-320-S99-6

+ Details

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

- Definition

Percentage added to reference rate used to compute variable rate on loan receivable.

+ References

No definition available.

+ Details

Name:	us-gaap_LoansReceivableBasisSpreadOnVariableRate
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The cash outflow associated with the purchase of or advances to an equity method investments, which are investments in joint ventures and entities in which the entity has an equity ownership interest normally of 20 to 50 percent and exercises significant influence.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 13
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482740/230-10-45-13

+ Details

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

- Definition

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

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 230
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 16
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482740/230-10-45-16

+ Details

Name:	us-gaap_ProceedsFromInterestReceived
Namespace Prefix:	us-gaap_
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/2003/role/disclosureRef
-Topic 850
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483326/850-10-50-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 850
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483326/850-10-50-1

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 850
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483326/850-10-50-3

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480738/235-10-S50-1

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(k)(2))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480678/235-10-S99-1

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(k)(1))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480678/235-10-S99-1

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 13
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481990/310-10-45-13

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6-07(2)(c)(2)(i))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479134/946-220-S99-1

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6-07(2)(c)(2)(ii))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479134/946-220-S99-1

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6-07(2)(g)(3))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479134/946-220-S99-1

+ Details

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

- Details

Name:	srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=abr_ClarusBerkleyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionAxis=abr_OtherRelatedPartyTransactionsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=us-gaap_RelatedPartyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	abr_LoansReceivableMaturityAxis=abr_MaturityDateFebruary2027Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=us-gaap_ImmediateFamilyMemberOfManagementOrPrincipalOwnerMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	abr_LoansReceivableMaturityAxis=abr_MaturityDateMay2026Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis=srt_SingleFamilyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=abr_AcquisitionFinancingAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_BridgeLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	abr_LoansReceivableMaturityAxis=abr_MaturityDateMay2027CommittedInMay2025Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	abr_LoansReceivableMaturityAxis=abr_MaturityDateNovember2028Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	abr_LoansReceivableMaturityAxis=abr_MaturityDateOctober2028Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	abr_LoansReceivableMaturityAxis=abr_MaturityDateAugust2026LoanOneMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	abr_LoansReceivableMaturityAxis=abr_MaturityDateNovember2025Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=abr_PreferredEquityInvestmentsInMortgageLoansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Agreements and Transactions with Related Parties - 2025 Activity (Details) $ in Thousands		1 Months Ended					3 Months Ended		12 Months Ended
	Apr. 30, 2025 USD ($)	Nov. 30, 2025 USD ($)	Oct. 31, 2025 USD ($)	Aug. 31, 2025 USD ($)	May 31, 2025 USD ($) officer	Feb. 28, 2025 USD ($)	Mar. 31, 2026 USD ($)	Mar. 31, 2025 USD ($)	Dec. 31, 2020 USD ($)	Jan. 31, 2025 USD ($)
Agreements and Transactions with Related Parties
Interest income							$ 235,047	$ 240,693
Loans and investments funded, originated and purchased							826,093	733,121
Clarus Berkley
Agreements and Transactions with Related Parties
Equity participation interest (as a percentage)		3.60%
Other Related Party Transactions \| Clarus Berkley
Agreements and Transactions with Related Parties
Noncontrolling interest		$ 1,500
Other Related Party Transactions \| Related Party \| Maturity Date February 2027
Agreements and Transactions with Related Parties
Base spread, percentage						4.75%				5.50%
Other Related Party Transactions \| Immediate Family Member of Management or Principal Owner \| Maturity Date May 2026 \| Single-Family Rental \| Preferred equity interest financing agreement
Agreements and Transactions with Related Parties
Interest income							800	1,000
Proceeds from interest received					$ 1,900
Other Related Party Transactions \| Immediate Family Member of Management or Principal Owner \| Maturity Date February 2027
Agreements and Transactions with Related Parties
Percentage of ownership interest of related party in the entity						10.00%
Bridge loans \| Related Party \| Maturity Date May 2027, Committed In May 2025
Agreements and Transactions with Related Parties
Interest income							1,000	1,400
Bridge loans \| Related Party \| Maturity Date February 2027
Agreements and Transactions with Related Parties
Interest income							700	200
Bridge loans \| Other Related Party Transactions \| Related Party
Agreements and Transactions with Related Parties
Principal amount		$ 67,900
Equity participation interest (as a percentage)		4.30%
Equity investments made by related parties		$ 1,800
Base spread, percentage		2.50%
SOFR floor, percentage		2.50%
Interest income							1,100
Bridge loans \| Other Related Party Transactions \| Related Party \| Maturity Date November 2028
Agreements and Transactions with Related Parties
Principal amount		$ 44,800
Equity participation interest (as a percentage)		1.00%
Base spread, percentage		4.25%
SOFR floor, percentage		3.50%
Loan committed							0
Financing receivable, length of extension period		1 year
Bridge loans \| Other Related Party Transactions \| Related Party \| Maturity Date October 2028
Agreements and Transactions with Related Parties
Principal amount			$ 50,500
Equity participation interest (as a percentage)			4.60%
Base spread, percentage			4.25%
SOFR floor, percentage			3.50%
Loan committed							0
Financing receivable, length of extension period			1 year
Bridge loans \| Other Related Party Transactions \| Related Party \| Maturity Date August 2026
Agreements and Transactions with Related Parties
Principal amount				$ 4,000
Base spread, percentage				3.25%
SOFR floor, percentage				4.32%
Interest income							100
Bridge loans \| Other Related Party Transactions \| Related Party \| Maturity Date May 2026 \| Single-Family Rental
Agreements and Transactions with Related Parties
Principal amount	$ 32,500				43,000
Loans and investments funded, originated and purchased					1,200				$ 3,500
Bridge loans \| Other Related Party Transactions \| Related Party \| Maturity Date November 2025 \| Single-Family Rental
Agreements and Transactions with Related Parties
Principal amount	$ 30,500				$ 36,200
Equity participation interest (as a percentage)					33.70%				18.90%
Base spread, percentage	4.25%				3.00%
SOFR floor, percentage	1.00%				3.25%
Interest income							700	$ 1,000
Proceeds from interest received					$ 1,300
Bridge loans \| Other Related Party Transactions \| Related Party \| Maturity Date May 2027, Committed In May 2025
Agreements and Transactions with Related Parties
Principal amount	$ 56,900				$ 58,400
Equity participation interest (as a percentage)					4.00%
Base spread, percentage	5.50%				2.75%
SOFR floor, percentage	3.25%				3.50%
Number of officers making minority equity investments \| officer					2
Equity investments					$ 500
Bridge loans \| Other Related Party Transactions \| Related Party \| Maturity Date February 2027
Agreements and Transactions with Related Parties
Principal amount						$ 52,600				$ 46,200
Equity participation interest (as a percentage)						70.00%
Loan committed							$ 31,300
Bridge loans \| Other Related Party Transactions \| Immediate Family Member of Management or Principal Owner \| Maturity Date May 2026 \| Single-Family Rental
Agreements and Transactions with Related Parties
Equity participation interest (as a percentage)					26.60%				21.80%
Base spread, percentage	3.75%				3.00%
SOFR floor, percentage	0.75%				3.25%
Preferred equity investments \| Other Related Party Transactions \| Related Party \| Maturity Date November 2025 \| Single-Family Rental
Agreements and Transactions with Related Parties
Loans and investments funded, originated and purchased									$ 4,600
Fixed rate of interest									12.00%
Preferred equity investments \| Other Related Party Transactions \| Immediate Family Member of Management or Principal Owner \| Maturity Date May 2026 \| Single-Family Rental
Agreements and Transactions with Related Parties
Fixed rate of interest					12.00%