Equity Method Investment, Sale of Ownership Percentage

No definition available.

Name:	ari_EquityMethodInvestmentSaleofOwnershipPercentage
Namespace Prefix:	ari_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Loss Contingency, Number of Lawsuits

+ References

No definition available.

+ Details

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

- Definition

Mortgage Loans on Real Estate, Commitment to Lend, Unfunded Amount

+ References

No definition available.

+ Details

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

- Definition

Other Commitment, Commitment Transfer

+ References

No definition available.

+ Details

Name:	ari_OtherCommitmentCommitmentTransfer
Namespace Prefix:	ari_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=66011266&loc=d3e33918-111571

+ Details

Name:	us-gaap_EquityMethodInvestmentOwnershipPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Minimum amount of other commitment not otherwise specified in the taxonomy. Excludes commitments explicitly modeled in the taxonomy, including but not limited to, long-term and short-term purchase commitments, recorded and unrecorded purchase obligations, supply commitments, registration payment arrangements, leases, debt, product warranties, guarantees, environmental remediation obligations, and pensions.

+ References

No definition available.

+ Details

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

- Definition

The cash inflow associated with the sale of 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://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Investing Activities
-URI http://asc.fasb.org/extlink&oid=6516133

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 12
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3179-108585

+ Details

Name:	us-gaap_ProceedsFromSaleOfEquityMethodInvestments
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

No definition available.

+ Details

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

- Details

Name:	us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=ari_KBCDPartnershipMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=ari_BKBBankMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_OtherCommitmentsAxis=ari_CommitmenttoInvestinKBCDMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_OtherCommitmentsAxis=ari_UnfundedCommitmentChampL.P.Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	invest_InvestmentAxis=ari_ChampLPMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=ari_ChampLPMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=ari_KBCBankDeutschlandAGMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=us-gaap_SubsidiariesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=ari_ChampLimitedPartnershipMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MortgageLoansOnRealEstateLoanTypeAxis=ari_CommercialMortgageLoansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MortgageLoansOnRealEstateLoanTypeAxis=ari_SubordinateMortgageLoansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Commitments and Contingencies - Additional Information (Detail) € in Thousands, $ in Thousands	1 Months Ended
	Jun. 30, 2016 EUR (€)	Feb. 28, 2015 EUR (€)	Feb. 28, 2015 USD ($)	Mar. 31, 2017 EUR (€)	Mar. 31, 2017 USD ($)	Dec. 31, 2016 USD ($) lawsuit	Jun. 30, 2016 USD ($)	Sep. 30, 2014 EUR (€)	Sep. 30, 2014 USD ($)	Sep. 30, 2013 EUR (€)	Sep. 30, 2013 USD ($)
Schedule of Equity Method Investments [Line Items]
Number of class action lawsuits \| lawsuit						2
Unfunded loan commitments					$ 121,470	$ 170,365
KBCD Partnership [Member]
Schedule of Equity Method Investments [Line Items]
Ownership interest										21.00%	21.00%
BKB Bank [Member]
Schedule of Equity Method Investments [Line Items]
Ownership interest				9.34%	9.34%
Commitment to Invest in KBCD [Member]
Schedule of Equity Method Investments [Line Items]
Commitment to invest/purchase				€ 38,000	$ 50,000			€ 38,000	$ 50,000	€ 38,000	$ 50,000
Unfunded Commitment, Champ L.P. [Member]
Schedule of Equity Method Investments [Line Items]
Commitment to invest/purchase	€ 2,802						$ 2,985
Commitment to invest transfer \| €	€ 427
Champ LP [Member]
Schedule of Equity Method Investments [Line Items]
Sale of equity method investment, percentage		48.00%	48.00%
Proceeds from sale of equity method investments		€ 16,314	$ 20,794
Champ LP [Member] \| KBC Bank Deutschland AG [Member]
Schedule of Equity Method Investments [Line Items]
Ownership interest								35.00%	35.00%	35.00%	35.00%
Wholly-owned Subsidiary [Member] \| Champ Limited Partnership [Member]
Schedule of Equity Method Investments [Line Items]
Ownership interest								59.00%	59.00%	59.00%	59.00%
Commercial Mortgage Loans [Member]
Schedule of Equity Method Investments [Line Items]
Unfunded loan commitments					121,470
Subordinate Mortgage Loans [Member]
Schedule of Equity Method Investments [Line Items]
Unfunded loan commitments					$ 121,470