Debt instrument extension period.

No definition available.

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

- Definition

Line of Credit Covenant, Consolidated Recourse Indebtedness

+ References

No definition available.

+ Details

Name:	ari_LineofCreditCovenantConsolidatedRecourseIndebtedness
Namespace Prefix:	ari_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Line of Credit, Covenant, Maximum Debt to Tangible Net Worth Ratio

+ References

No definition available.

+ Details

Name:	ari_LineofCreditCovenantMaximumDebttoTangibleNetWorthRatio
Namespace Prefix:	ari_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	duration

- Definition

Line of Credit Covenant, Minimum EBITDA to Interest Expense Ratio

+ References

No definition available.

+ Details

Name:	ari_LineofCreditCovenantMinimumEBITDAtoInterestExpenseRatio
Namespace Prefix:	ari_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	duration

- Definition

Line of Credit Covenant, Minimum Liquidity

+ References

No definition available.

+ Details

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

- Definition

Line of Credit Covenant, Minimum Liquidity Percentage

+ References

No definition available.

+ Details

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

- Definition

Line of Credit Facility, Covenant Terms, Minimum Consolidated Tangible Net Worth Covenant, Amount

+ References

No definition available.

+ Details

Name:	ari_LineofCreditFacilityCovenantTermsMinimumConsolidatedTangibleNetWorthCovenantAmount
Namespace Prefix:	ari_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Line of Credit Facility, Covenant Terms, Minimum Consolidated Tangible Net Worth Covenant, Percentage of Additional Net Cash Proceeds

+ References

No definition available.

+ Details

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

- Definition

Line of Credit Facility, Covenant Terms, Minimum Net Income During Four Consecutive Quarters

+ References

No definition available.

+ Details

Name:	ari_LineofCreditFacilityCovenantTermsMinimumNetIncomeDuringFourConsecutiveQuarters
Namespace Prefix:	ari_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Line of Credit Facility, Covenant Terms, Total Recourse Indebtedness, Percent

+ References

No definition available.

+ Details

Name:	ari_LineofCreditFacilityCovenantTermsTotalRecourseIndebtednessPercent
Namespace Prefix:	ari_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Line of Credit Facility, Estimated Fair Value of Collateral Pledged Percentage

+ References

No definition available.

+ Details

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

- Definition

Line of Credit Facility, Threshold Amount for Margin Calls

+ References

No definition available.

+ Details

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

- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
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_DebtInstrumentLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentTerm
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- 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

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 210.5-02.19(b),22(b))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19, 22

-Article 5

+ Details

Name:	us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
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_GoldmanSachsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_LondonInterbankOfferedRateLIBORMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	us-gaap_DebtInstrumentAxis=ari_AmendedandRestatedJPMorganFacilityMember
Namespace Prefix:
Data Type:	na
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Borrowings Under Repurchase Agreements - Additional Information (Detail) - Line of Credit [Member]			1 Months Ended	9 Months Ended	12 Months Ended
	Jan. 29, 2015 USD ($)	Jan. 26, 2015 USD ($)	Jun. 30, 2015 USD ($)	Sep. 30, 2015	Dec. 31, 2014
Goldman Sachs [Member] \| London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument [Line Items]
Basis point				3.50%	3.50%
Minimum [Member] \| JP Morgan Chase [Member] \| London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument [Line Items]
Basis point				2.25%	2.25%
Maximum [Member] \| JP Morgan Chase [Member] \| London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument [Line Items]
Basis point				3.50%	3.50%
Goldman Facility [Member] \| Goldman Sachs [Member]
Debt Instrument [Line Items]
Maximum borrowing under facility		$ 52,524,000
Covenant terms, minimum consolidated tangible net worth, amount		$ 750,000,000
Covenant terms, maximum debt to tangible net worth ratio		3
Covenant terms, minimum liquidity		$ 15,000,000
Line of credit facility, covenant terms, total consolidated indebtedness, percent		5.00%
Line of credit facility, covenant terms, minimum net income during any four consecutive quarters		$ 1
Covenant terms, minimum EBITDA to interest expense ratio		1.5
Goldman Facility [Member] \| Goldman Sachs [Member] \| London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument [Line Items]
Basis point		3.50%
Amended and Restated JPMorgan Facility [Member] \| JP Morgan Chase [Member]
Debt Instrument [Line Items]
Maximum borrowing under facility	$ 300,000,000		$ 400,000,000
Covenant terms, minimum consolidated tangible net worth, amount	$ 750,000,000
Covenant terms, maximum debt to tangible net worth ratio	3
Term of debt instrument			2 years
Debt extension option			1 year
Threshold amount for margin calls (more than)	$ 250,000
Covenant terms, minimum consolidated tangible net worth, percentage of net cash proceeds	75.00%
Covenant terms, minimum liquidity, percentage	5.00%
Covenant terms, consolidated recourse indebtedness	$ 15,000,000
Amended and Restated JPMorgan Facility [Member] \| Minimum [Member] \| JP Morgan Chase [Member]
Debt Instrument [Line Items]
Estimated fair value of collateral pledged, percentage	25.00%
Amended and Restated JPMorgan Facility [Member] \| Minimum [Member] \| JP Morgan Chase [Member] \| London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument [Line Items]
Basis point	2.25%
Amended and Restated JPMorgan Facility [Member] \| Maximum [Member] \| JP Morgan Chase [Member]
Debt Instrument [Line Items]
Estimated fair value of collateral pledged, percentage	80.00%
Amended and Restated JPMorgan Facility [Member] \| Maximum [Member] \| JP Morgan Chase [Member] \| London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument [Line Items]
Basis point	4.75%