Amount of write-down of assets recognized in the income statement. Includes, but is not limited to, losses from tangible assets, intangible assets and goodwill.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 45
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=68055307&loc=d3e2420-110228

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3602-108585

+ Details

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

- Definition

Amount, after adjustment, of cost-method investment. Adjustments include, but are not limited to, dividends received in excess of earnings after date of investment that are considered a return of investment and other than temporary impairments.

+ 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 210.5-02.12)
-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 325
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=75025870&loc=d3e40691-111596

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 325
-SubTopic 20
-Section 35
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=75027002&loc=d3e40346-111594

+ Details

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

- Definition

Amount of distribution received from equity method investee for return on investment, classified as operating activities. Excludes distribution for return of investment, classified as investing activities.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 225
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04(10))
-URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3602-108585

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(12))
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 21D
-URI http://asc.fasb.org/extlink&oid=98514028&loc=SL94080555-108585

+ Details

Name:	us-gaap_EquityMethodInvestmentDividendsOrDistributions
Namespace Prefix:	us-gaap_
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

The difference between the carrying value and the sale price of real estate or properties that were intended to be sold or held for capital appreciation or rental income. This element refers to the gain (loss) included in earnings and not to the cash proceeds of the sale. This element is a noncash adjustment to net income when calculating net cash generated by operating activities using the indirect method.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3602-108585

+ Details

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

- Definition

This item represents the entity's proportionate share for the period of the net income (loss) of its investee (such as unconsolidated subsidiaries and joint ventures) to which the equity method of accounting is applied. This item includes income or expense related to stock-based compensation based on the investor's grant of stock to employees of an equity method investee.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(12))
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 225
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04(10))
-URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3602-108585

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=66022249&loc=d3e33749-111570

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 225
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04(13)(f))
-URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882

+ Details

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

- References

No definition available.

+ Details

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

- Definition

The number of real estate properties owned as of the balance sheet date.

+ References

No definition available.

+ Details

Name:	us-gaap_NumberOfRealEstateProperties
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

A tax based on the assessed value of real estate by the local government. The tax is usually based on the value of property (including the land).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 720
-SubTopic 30
-Section 45
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=6419918&loc=d3e35301-107843

+ Details

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

- Definition

The cash outflow to repay long-term debt that is wholly or partially secured by collateral. Excludes repayments of tax exempt secured debt.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3291-108585

+ Details

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

- Definition

Advisory Fee Percentage

+ References

No definition available.

+ Details

Name:	wpc_AdvisoryFeePercentage
Namespace Prefix:	wpc_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Aggregate Unamortized Basis Difference On Equity Investments

+ References

No definition available.

+ Details

Name:	wpc_AggregateUnamortizedBasisDifferenceOnEquityInvestments
Namespace Prefix:	wpc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Asset management fees receivable, shares

+ References

No definition available.

+ Details

Name:	wpc_Assetmanagementfeesreceivableshares
Namespace Prefix:	wpc_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

The Increase (Decrease) in ownership interest In equity investments.

+ References

No definition available.

+ Details

Name:	wpc_IncreaseDecreaseInOwnershipInterestInEquityInvestments
Namespace Prefix:	wpc_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Total Mortgage Debt On Tenancy In common

+ References

No definition available.

+ Details

Name:	wpc_MortgageDebtOnTenancyInCommon
Namespace Prefix:	wpc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Cash outflows to equity method investments during the period.

+ References

No definition available.

+ Details

Name:	wpc_PaymentstoEquityMethodInvestments
Namespace Prefix:	wpc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Pro Rata Share Mortgage Debt On Tenancy In Common

+ References

No definition available.

+ Details

Name:	wpc_ProRataShareMortgageDebtOnTenancyInCommon
Namespace Prefix:	wpc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	us-gaap_StatementGeographicalAxis=country_DE
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementScenarioAxis=us-gaap_ScenarioAdjustmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	us-gaap_BusinessAcquisitionAxis=wpc_Cpa16Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BusinessAcquisitionAxis=wpc_Cpa15Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	wpc_ThirdPartyAxis=wpc_PropcoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	wpc_EquityInvestmentsAxis=wpc_OwnedRealEstateSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RealEstatePropertiesAxis=us-gaap_UnconsolidatedPropertiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionAxis=wpc_CPA17Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

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

- Details

Name:	us-gaap_RelatedPartyTransactionAxis=wpc_Cpa17OperatingPartnershipMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionAxis=wpc_CorporatePropertyAssociatesEighteenMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementClassOfStockAxis=us-gaap_CommonClassAMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionAxis=wpc_CorporatePropertyAssociatesEighteenOperatingPartnerMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionAxis=wpc_CwiMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionAxis=wpc_CwiOperatingPartnershipMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionAxis=wpc_CareyWatermarkIncorporatedTwoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionAxis=wpc_CareyWatermarkInvestors2OperatingPartnershipMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionAxis=wpc_CareyCreditIncomeFundMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionAxis=wpc_CareyEuropeanStudentHousingFundIL.P.Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	wpc_RelatedPartyFeesBasisAxis=wpc_GrossProceedsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionAxis=wpc_ManagedProgramsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_IncomeStatementLocationAxis=wpc_ImpairmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_IncomeStatementLocationAxis=wpc_GainOnSaleOfRealEstateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionAxis=wpc_Cpa14Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionAxis=wpc_Cpa15Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionAxis=wpc_Cpa16Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionAxis=wpc_CPAReitsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BalanceSheetLocationAxis=us-gaap_OtherAssetsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Equity Investments in the Managed Programs and Real Estate - Narratives (Details)	1 Months Ended		3 Months Ended		12 Months Ended
	Oct. 31, 2013 USD ($)	Nov. 30, 2010	Sep. 30, 2015 USD ($) property	Jun. 30, 2015 USD ($)	Dec. 31, 2017 USD ($) shares	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2007 property
Investments in REITs
Distributions of earnings from equity method investments					$ 66,259,000	$ 64,650,000	$ 51,435,000
Equity in earnings of equity method investments in the Managed Programs and real estate					64,750,000	64,719,000	51,020,000
Gain or loss on sale of investment properties					33,878,000	71,318,000	6,487,000
Real estate tax expense, adjustment					(59,300,000)	(56,000,000)	(57,700,000)
Payment of mortgage loan					344,440,000	161,104,000	90,328,000
Germany \| Adjustments
Investments in REITs
Real estate tax expense, adjustment							25,000,000
Hellweg 2
Investments in REITs
Equity in earnings of equity method investments in the Managed Programs and real estate	$ (8,400,000)
Hellweg 2 \| CPA: 16 - Global \| Germany \| Adjustments
Investments in REITs
Real estate tax expense, adjustment							17,100,000
Hellweg 2 \| CPA:15 \| Germany \| Adjustments
Investments in REITs
Real estate tax expense, adjustment							7,900,000
Hellweg 2 \| Propco
Investments in REITs
Equity method investment, ownership percentage	5.00%							75.00%
Number of real estate properties \| property								37
Real estate tax expense, adjustment	$ (22,100,000)
Owned Real Estate \| Unconsolidated Properties
Investments in REITs
Distributions of earnings from equity method investments					$ 16,000,000	16,100,000	13,300,000
CPA:17 – Global
Investments in REITs
Asset management fees receivable, shares \| shares					240,800
Distributions of earnings from equity method investments					$ 8,400,000	$ 7,300,000	5,900,000
Equity method investment, ownership percentage					4.186%	3.456%
CPA:17 – Global \| Owned Real Estate \| C1000 Logestiek Vastgoed B.V.
Investments in REITs
Mortgage debt tenants in common					$ 76,200,000
Pro rata share mortgage debt on tenancy in common					$ 11,400,000
Equity method investment, ownership percentage					15.00%
CPA:17 – Global \| Owned Real Estate \| Waldaschaff Automotive GmbH and Wagon Automotive Nagold GmbH
Investments in REITs
Equity in earnings of equity method investments in the Managed Programs and real estate				$ 2,100,000
Equity method investment, ownership percentage					33.00%
Number of real estate properties \| property			2
Contributions to equity method investments			$ 4,700,000
Payment of mortgage loan			$ 14,300,000
CPA:17 - Global operating partnership
Investments in REITs
Distributions of earnings from equity method investments					$ 26,700,000	$ 24,800,000	24,700,000
Equity method investment, ownership percentage					0.009%	0.009%
CPA:18 – Global
Investments in REITs
Distributions of earnings from equity method investments					$ 1,700,000	$ 900,000	200,000
Equity method investment, ownership percentage					2.54%	1.616%
CPA:18 – Global \| Class A
Investments in REITs
Asset management fees receivable, shares \| shares					116,255
CPA:18 - Global operating partnership
Investments in REITs
Distributions of earnings from equity method investments					$ 8,700,000	$ 7,600,000	6,300,000
Equity method investment, ownership percentage					0.034%	0.034%
CWI 1
Investments in REITs
Asset management fees receivable, shares \| shares					114,456
Distributions of earnings from equity method investments					$ 1,100,000	$ 900,000	800,000
Equity method investment, ownership percentage					2.119%	1.109%
CWI operating partnership
Investments in REITs
Distributions of earnings from equity method investments					$ 7,500,000	$ 9,400,000	7,100,000
Equity method investment, ownership percentage					0.015%	0.015%
CWI 2
Investments in REITs
Distributions of earnings from equity method investments					$ 400,000	$ 100,000
Equity method investment, ownership percentage					1.786%	0.773%
CWI 2 \| Class A
Investments in REITs
Asset management fees receivable, shares \| shares					77,990
CWI 2 operating partnership
Investments in REITs
Distributions of earnings from equity method investments					$ 5,100,000	$ 3,300,000	300,000
Equity method investment, ownership percentage					0.015%	0.015%
CCIF
Investments in REITs
Distributions of earnings from equity method investments					$ 900,000	$ 700,000	800,000
Equity method investment, ownership percentage					0.00%	13.322%
CESH I
Investments in REITs
Distributions of earnings from equity method investments					$ 0	$ 0
Equity method investment, ownership percentage					2.43%	2.431%
CESH I \| Gross proceeds
Investments in REITs
Advisory fee percentage					2.50%
Managed Programs
Investments in REITs
Aggregate unamortized basis difference on equity investments					$ 42,500,000	$ 31,700,000
Other-than-temporary impairment charges					37,500,000	35,700,000	7,200,000
Gain or loss on sale of investment properties					19,300,000	132,800,000	8,900,000
Managed Programs \| Impairment
Investments in REITs
Equity in earnings of equity method investments in the Managed Programs and real estate					(1,600,000)	(1,100,000)	(100,000)
Managed Programs \| Gain on sale of real estate
Investments in REITs
Equity in earnings of equity method investments in the Managed Programs and real estate					500,000	$ 4,600,000	$ 100,000
CPA:14 \| Hellweg 2
Investments in REITs
Equity method investment, ownership percentage								33.00%
CPA:15 \| Hellweg 2
Investments in REITs
Equity method investment, ownership percentage								40.00%
CPA: 16 - Global \| Hellweg 2
Investments in REITs
Equity method investment, ownership percentage								27.00%
CPA 14, 15, and 16 \| Hellweg 2
Investments in REITs
Equity method investment, ownership percentage		95.00%						25.00%
Increase in ownership interest in equity method investment		70.00%
Other assets \| CCIF
Investments in REITs
Cost of equity method investment					$ 23,300,000