Fair Value of Financial Instruments (Reconciliation of Instrument with Unobservable Inputs) (Detail) (Fair Value, Inputs, Level 3 [Member], USD $) In Thousands, unless otherwise specified	9 Months Ended
Sep. 30, 2014
Fair Value, Assets (Liabilities), Net Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance as of December 31, 2013	$ 43,847
Unrealized gain included in other comprehensive income, net	9,456
Changes in fair value included in net income, net	(14,564)
Fair value at purchase/issuance	147,591
Sale of CMBS acquired in the Cole Merger	(151,248)
Reclassification of previous unrealized gains on investment securities into net loss-CMBS	(7,417)
Return of principal received	(3,678)
Amortization included in net income, net	184
Reclassification of contingent consideration to held for sale	4,596
Redemption of Series D	30,310
Ending balance	59,077
Commercial Mortgage Backed Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance as of December 31, 2013	60,583
Unrealized gain included in other comprehensive income, net	9,456
Changes in fair value included in net income, net	0
Fair value at purchase/issuance	151,197
Sale of CMBS acquired in the Cole Merger	(151,248)
Reclassification of previous unrealized gains on investment securities into net loss-CMBS	(7,417)
Return of principal received	(3,678)
Amortization included in net income, net	184
Reclassification of contingent consideration to held for sale	0
Redemption of Series D	0
Ending balance	59,077
Series D Preferred Stock Embedded Derivative [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance as of December 31, 2013	(16,736)
Unrealized gain included in other comprehensive income, net	0
Changes in fair value included in net income, net	(13,574)
Fair value at purchase/issuance	0
Sale of CMBS acquired in the Cole Merger	0
Reclassification of previous unrealized gains on investment securities into net loss-CMBS	0
Return of principal received	0
Amortization included in net income, net	0
Reclassification of contingent consideration to held for sale	0
Redemption of Series D	30,310
Ending balance	0
Contingent Consideration [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance as of December 31, 2013	0
Unrealized gain included in other comprehensive income, net	0
Changes in fair value included in net income, net	(990)
Fair value at purchase/issuance	(3,606)
Sale of CMBS acquired in the Cole Merger	0
Reclassification of previous unrealized gains on investment securities into net loss-CMBS	0
Return of principal received	0
Amortization included in net income, net	0
Reclassification of contingent consideration to held for sale	4,596
Redemption of Series D	0
Ending balance	$ 0

Name:	arcp_FairValueAssetsLiabilitiesNetMeasuredonRecurringBasisUnobservableInputReconciliationCalculationRollForward
Namespace Prefix:	arcp_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Amortization Included in Earnings

+ References

No definition available.

+ Details

Name:	arcp_FairValueMeasurementwithUnobservableInputsReconciliationRecurringBasisAssetAmortizationIncludedinEarnings
Namespace Prefix:	arcp_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset (Liability), Net, Amortization Included in Earnings

+ References

No definition available.

+ Details

Name:	arcp_FairValueMeasurementwithUnobservableInputsReconciliationRecurringBasisAssetLiabilityNetAmortizationIncludedinEarnings
Namespace Prefix:	arcp_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset (Liability), Net, Gain (Loss) Included in Earnings

+ References

No definition available.

+ Details

Name:	arcp_FairValueMeasurementwithUnobservableInputsReconciliationRecurringBasisAssetLiabilityNetGainLossIncludedinEarnings
Namespace Prefix:	arcp_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset (Liability), Net, Gain (Loss) Included in Other Comprehensive Income (Loss)

+ References

No definition available.

+ Details

Name:	arcp_FairValueMeasurementwithUnobservableInputsReconciliationRecurringBasisAssetLiabilityNetGainLossIncludedinOtherComprehensiveIncomeLoss
Namespace Prefix:	arcp_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Fair Value Measurement with Unobservable Inputs Reconciliation Recurring Basis Asset Liability Net Transfers Out Of Level3

+ References

No definition available.

+ Details

Name:	arcp_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetLiabilityNetTransfersOutOfLevel3
Namespace Prefix:	arcp_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset (Liability), Net Value

+ References

No definition available.

+ Details

Name:	arcp_FairValueMeasurementwithUnobservableInputsReconciliationRecurringBasisAssetLiabilityNetValue
Namespace Prefix:	arcp_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Fair Value Measurement with Unobservable Inputs Reconciliation Recurring Basis Asset Liability Purchases And Issuances

+ References

No definition available.

+ Details

Name:	arcp_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetLiabilityPurchasesAndIssuances
Namespace Prefix:	arcp_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Fair Value Measurement with Unobservable Inputs Reconciliation Recurring Basis Asset Liability Reclassification Of Unrealized Gain Loss To Realized Gain Loss In Earnings

+ References

No definition available.

+ Details

Name:	arcp_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetLiabilityReclassificationOfUnrealizedGainLossToRealizedGainLossInEarnings
Namespace Prefix:	arcp_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Fair Value Measurement with Unobservable Inputs Reconciliation Recurring Basis Asset Liability Return Of Principal

+ References

No definition available.

+ Details

Name:	arcp_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetLiabilityReturnOfPrincipal
Namespace Prefix:	arcp_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Liability Sales

+ References

No definition available.

+ Details

Name:	arcp_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetLiabilitySales
Namespace Prefix:	arcp_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Fair Value Measurement with Unobservable Inputs Reconciliation Recurring Basis Asset Reclassification Of Unrealized Gain Loss To Realized Gain Loss In Earnings

+ References

No definition available.

+ Details

Name:	arcp_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetReclassificationOfUnrealizedGainLossToRealizedGainLossInEarnings
Namespace Prefix:	arcp_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Fair Value Measurement with Unobservable Inputs Reconciliation Recurring Basis Asset Return of Principal

+ References

No definition available.

+ Details

Name:	arcp_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetReturnOfPrincipal
Namespace Prefix:	arcp_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Fair Value Measurement with Unobservable Inputs Reconciliation Recurring Basis Assets Liability Redemptions

+ References

No definition available.

+ Details

Name:	arcp_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetsLiabilityRedemptions
Namespace Prefix:	arcp_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Fair Value Measurement with Unobservable Inputs Reconciliation Recurring Basis Assets Redemptions

+ References

No definition available.

+ Details

Name:	arcp_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetsRedemptions
Namespace Prefix:	arcp_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

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

- Definition

Amount of purchases of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)(2)

-URI http://asc.fasb.org/extlink&oid=36462937&loc=d3e19207-110258

+ Details

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

- Definition

Amount of sale of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

+ References

+ Details

Name:	us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of transfers of financial instrument classified as an asset out of level 3 of the fair value hierarchy.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)(3)

-URI http://asc.fasb.org/extlink&oid=36462937&loc=d3e19207-110258

+ Details

Name:	us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Fair value of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=36462937&loc=d3e19207-110258

+ Details

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

- Definition

Amount of gain (loss) recognized on the income statement for financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)(1)

-URI http://asc.fasb.org/extlink&oid=36462937&loc=d3e19207-110258

+ Details

Name:	us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityGainLossIncludedInEarnings
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of gain (loss) recognized in other comprehensive income (loss) for financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)(1a)

-URI http://asc.fasb.org/extlink&oid=36462937&loc=d3e19207-110258

+ Details

Name:	us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityGainLossIncludedInOtherComprehensiveIncome
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Fair value of financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=36462937&loc=d3e19207-110258

+ Details

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