Number of states accounted for more than 4% of unpaid principal balance and related servicing revenues.

No definition available.

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Period Type:	duration

- Definition

Percentage of servicing fee on loans.

+ References

No definition available.

+ Details

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

- Definition

Amount of interest income earned, net of interest paid to the borrower.

+ References

No definition available.

+ Details

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

- Definition

The percentage of unpaid principal balance to total unpaid principal balance as of the balance sheet date.

+ References

No definition available.

+ Details

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

- References

No definition available.

+ Details

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

- Definition

The designation of funds furnished by a borrower to a lender to assure future payments of the borrower's real estate taxes and insurance obligations with respect to a mortgaged property. Escrow deposits may be made for a variety of other purposes such as earnest money and contingent payments. This element excludes replacement reserves which are an escrow separately provided for within the US GAAP taxonomy.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.10)
-URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 954
-SubTopic 440
-Section 50
-Paragraph 1
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=6491277&loc=d3e6429-115629

+ Details

Name:	us-gaap_EscrowDeposit
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

This is the result of the principal amount outstanding of total loans managed or securitized less securitized loans and loans that are in the process of being securitized.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121570589&loc=d3e107314-111719

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Mortgage Servicing (Details) $ in Thousands	12 Months Ended
Mortgage Servicing (Details) $ in Thousands	Dec. 31, 2021 USD ($) state	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Mortgage Servicing
Interest earned on total escrows	$ 4,200	$ 7,100	$ 17,300
Fee-based servicing portfolio
Mortgage Servicing
Escrow Deposit	1,990,000	1,290,000
MSRs
Mortgage Servicing
Unpaid principal balance of loans serviced	$ 26,959,389	$ 24,628,456
Weighted average servicing fee (as a percent)	0.449%	0.454%
MSRs \| Fee-based servicing portfolio
Mortgage Servicing
UPB Percentage of Total	100.00%	100.00%
Escrow Deposit	$ 682,500	$ 867,600
Texas \| MSRs \| Fee-based servicing portfolio
Mortgage Servicing
UPB Percentage of Total	12.00%	16.00%
New York \| MSRs \| Fee-based servicing portfolio
Mortgage Servicing
UPB Percentage of Total	11.00%	9.00%
North Carolina \| MSRs \| Fee-based servicing portfolio
Mortgage Servicing
UPB Percentage of Total	9.00%	9.00%
California \| MSRs \| Fee-based servicing portfolio
Mortgage Servicing
UPB Percentage of Total	8.00%	9.00%
Florida \| MSRs \| Fee-based servicing portfolio
Mortgage Servicing
UPB Percentage of Total	6.00%	7.00%
Georgia \| MSRs \| Fee-based servicing portfolio
Mortgage Servicing
UPB Percentage of Total	6.00%	6.00%
New Jersey \| MSRs \| Fee-based servicing portfolio
Mortgage Servicing
UPB Percentage of Total	6.00%	4.00%
Other States \| MSRs \| Fee-based servicing portfolio
Mortgage Servicing
UPB Percentage of Total	42.00%	40.00%
Number of states accounted for more than 4% of UPB and related servicing revenues \| state	0
Fannie Mae \| MSRs
Mortgage Servicing
Unpaid principal balance of loans serviced	$ 19,127,397	$ 18,268,268
Fannie Mae \| MSRs \| Fee-based servicing portfolio
Mortgage Servicing
UPB Percentage of Total	71.00%	74.00%
Freddie Mac \| MSRs
Mortgage Servicing
Unpaid principal balance of loans serviced	$ 4,943,905	$ 4,881,080
Freddie Mac \| MSRs \| Fee-based servicing portfolio
Mortgage Servicing
UPB Percentage of Total	18.00%	20.00%
Private Label \| MSRs
Mortgage Servicing
Unpaid principal balance of loans serviced	$ 1,711,326	$ 726,992
Private Label \| MSRs \| Fee-based servicing portfolio
Mortgage Servicing
UPB Percentage of Total	6.00%	3.00%
FHA \| MSRs
Mortgage Servicing
Unpaid principal balance of loans serviced	$ 985,063	$ 752,116
FHA \| MSRs \| Fee-based servicing portfolio
Mortgage Servicing
UPB Percentage of Total	4.00%	3.00%
SFR - Fixed Rate. \| MSRs
Mortgage Servicing
Unpaid principal balance of loans serviced	$ 191,698
SFR - Fixed Rate. \| MSRs \| Fee-based servicing portfolio
Mortgage Servicing
UPB Percentage of Total	1.00%