Secured Debt Arrangements, Net - Commercial Mortgage Loans Pledged to the Barclays Private Securitization (Details) $ in Thousands	Mar. 31, 2024 USD ($) contract	Dec. 31, 2023 USD ($) contract
Line of Credit
Line of Credit Facility [Line Items]
Balance	$ 5,610,491	$ 5,551,809
Line of Credit \| Barclays Securitization
Line of Credit Facility [Line Items]
Balance	2,056,364	2,157,157
VIE
Line of Credit Facility [Line Items]
Mortgage loans on real estate, commercial and consumer, net	$ 2,775,504	$ 2,903,186
VIE \| Line of Credit \| Barclays Securitization
Line of Credit Facility [Line Items]
Count \| contract	13	14
Balance	$ 2,803,986,000	$ 2,931,817,000
Mortgage loans on real estate, commercial and consumer, net	$ 2,775,504,000	$ 2,903,186,000
VIE \| Fx contracts - GBP \| Line of Credit \| Barclays Securitization
Line of Credit Facility [Line Items]
Count \| contract	7	7
Balance	$ 1,704,318,000	$ 1,662,457,000
Mortgage loans on real estate, commercial and consumer, net	$ 1,685,240,000	$ 1,643,979,000
VIE \| Fx contracts - EUR \| Line of Credit \| Barclays Securitization
Line of Credit Facility [Line Items]
Count \| contract	5	6
Balance	$ 867,551,000	$ 1,021,272,000
Mortgage loans on real estate, commercial and consumer, net	$ 859,740,000	$ 1,012,987,000
VIE \| SEK \| Line of Credit \| Barclays Securitization
Line of Credit Facility [Line Items]
Count \| contract	1	1
Balance	$ 232,117,000	$ 248,088,000
Mortgage loans on real estate, commercial and consumer, net	$ 230,524,000	$ 246,220,000

Number Of Mortgage Loans

No definition available.

Name:	ari_NumberOfMortgageLoans
Namespace Prefix:	ari_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- 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 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(f))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480678/235-10-S99-1

+ Details

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

- Definition

The balance represents the amount of loans that are secured by real estate mortgages, offset by the reserve to cover probable credit losses on the loan portfolio.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(1)(c))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479440/944-210-S99-1

+ Details

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

- Definition

Amount, before effects of master netting arrangements, of funds outstanding borrowed in the form of a security repurchase agreement between the entity and another party for the sale and repurchase of identical or substantially the same securities at a date certain for a specified price. Includes liabilities elected not to be offset. Excludes liabilities not subject to a master netting arrangement.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 210
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483466/210-20-50-3

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 210
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 7
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483444/210-20-55-7

+ Details

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

- Details

Name:	us-gaap_CreditFacilityAxis=us-gaap_LineOfCreditMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LineOfCreditFacilityAxis=ari_BarclaysSecuritizationMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ConsolidatedEntitiesAxis=us-gaap_VariableInterestEntityPrimaryBeneficiaryMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_CurrencyAxis=currency_GBP
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_CurrencyAxis=currency_EUR
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_CurrencyAxis=currency_SEK
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: