Debt instrument extension period.

No definition available.

Name:	ari_DebtInstrumentExtensionPeriod
Namespace Prefix:	ari_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Debt Instrument, Number of Extensions Available

+ References

No definition available.

+ Details

Name:	ari_DebtInstrumentNumberofExtensionsAvailable
Namespace Prefix:	ari_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Mortgage Loans on Real Estate, Funded Amount of Mortgages

+ References

No definition available.

+ Details

Name:	ari_MortgageLoansonRealEstateFundedAmountofMortgages
Namespace Prefix:	ari_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(16))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

+ Details

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

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

+ Details

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

- Definition

Amount of the contractual principal due at the origination of the mortgage loan (face amount).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 948
-SubTopic 310
-Section S99
-Paragraph 1
-Subparagraph (SX 210.12-29)
-URI http://asc.fasb.org/extlink&oid=6589523&loc=d3e617274-123014

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 10
-Section S99
-Paragraph 6
-Subparagraph (SX 210.5-04.(c) Schedule IV)
-URI http://asc.fasb.org/extlink&oid=27047687&loc=d3e5864-122674

+ Details

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

- Definition

The cash inflow from repayments of the balance excluding interest (principal) on loans receivable and leases held for investment purposes.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 12
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3179-108585

+ Details

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

- Definition

Detail information of subsequent event by type. User is expected to use existing line items from elsewhere in the taxonomy as the primary line items for this disclosure, which is further associated with dimension and member elements pertaining to a subsequent event.

+ References

No definition available.

+ Details

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Period Type:	duration

- Details

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

- Details

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

- Details

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

- Details

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

- Details

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

- Details

Name:	us-gaap_DebtInstrumentAxis=ari_AssetSpecificFinancingMember
Namespace Prefix:
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Subsequent Events (Details) £ in Millions			1 Months Ended
Subsequent Events (Details) £ in Millions	Apr. 27, 2018 USD ($) extension	Mar. 31, 2017 USD ($) extension	May 02, 2018 USD ($)	Mar. 31, 2018 USD ($)	Mar. 31, 2018 GBP (£)	Dec. 31, 2017 USD ($)	Mar. 31, 2017 GBP (£)
Subsequent Event [Member]
Subsequent Event [Line Items]
Funded amount of mortgages			$ 20,400,000
Proceeds from loan repayments			71,900,000
Commercial Mortgage Portfolio Segment [Member] \| Subsequent Event [Member]
Subsequent Event [Line Items]
Original face amount			238,800,000.0
Funded amount of mortgages			$ 236,300,000
Line of Credit [Member]
Subsequent Event [Line Items]
Maximum borrowing under facility				$ 2,277,906,000		$ 2,290,139,000
DB Repurchase Facility [Member] \| Line of Credit [Member]
Subsequent Event [Line Items]
Maximum borrowing under facility		$ 568,200,000
Debt instrument, number of extension available \| extension		1
General Facility [Member] \| DB Repurchase Facility [Member] \| Line of Credit [Member]
Subsequent Event [Line Items]
Maximum borrowing under facility		$ 450,000,000					£ 73.3
Line of credit, amount outstanding		102,400,000		450,000,000			£ 45.0
General Facility [Member] \| DB Repurchase Facility [Member] \| Line of Credit [Member] \| Subsequent Event [Member]
Subsequent Event [Line Items]
Maximum borrowing under facility	$ 800,000,000.0
Debt instrument, number of extension available \| extension	1
Extension option	1 year
Asset Specific Financing [Member] \| DB Repurchase Facility [Member] \| Line of Credit [Member]
Subsequent Event [Line Items]
Line of credit, amount outstanding		$ 55,100,000		$ 55,100,000	£ 45.0
Asset Specific Financing [Member] \| DB Repurchase Facility [Member] \| Line of Credit [Member] \| Subsequent Event [Member]
Subsequent Event [Line Items]
Line of credit, amount outstanding	$ 55,100,000