Business and Organization - Narratives (Details) ft² in Millions	6 Months Ended
Jun. 30, 2021 ft² property tenant	Jan. 31, 2020 property
Real Estate
Additional disclosures
Number of real estate properties (property)	1,266
Square footage of real estate properties \| ft²	150.0
Number of tenants (tenant) \| tenant	356
Lease term (years)	10 years 9 months 18 days
Occupancy rate	98.00%
Real Estate \| Operating properties
Additional disclosures
Number of real estate properties (property)	20
Square footage of real estate properties \| ft²	1.4
Real Estate \| Self-storage
Additional disclosures
Number of real estate properties (property)	19
Real Estate \| Hotel
Additional disclosures
Number of real estate properties (property)	1	2
Investment Management \| Affiliated Entity \| Managed Programs
Additional disclosures
Number of tenants (tenant) \| tenant	65
Occupancy rate	98.70%
Investment Management \| Affiliated Entity \| Managed Programs \| Built-to-suit
Additional disclosures
Number of real estate properties (property)	10
Investment Management \| Operating properties \| Affiliated Entity \| Managed Programs
Additional disclosures
Number of real estate properties (property)	69
Square footage of real estate properties \| ft²	5.6
Investment Management \| Net- lease properties \| Affiliated Entity \| Managed Programs
Additional disclosures
Number of real estate properties (property)	52
Square footage of real estate properties \| ft²	10.6

Area of a real estate property.

No definition available.

Name:	us-gaap_AreaOfRealEstateProperty
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:areaItemType
Balance Type:	na
Period Type:	instant

- Definition

Term of lessor's operating lease, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 30
-Section 50
-Paragraph 3
-Subparagraph (a)(3)
-URI http://asc.fasb.org/extlink&oid=124258985&loc=SL77919359-209981

+ Details

Name:	us-gaap_LessorOperatingLeaseTermOfContract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	instant

- 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

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

+ References

No definition available.

+ Details

Name:	wpc_NumberOfTenants
Namespace Prefix:	wpc_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

The occupancy rate of our owned real estate properties as of the balance sheet date.

+ References

No definition available.

+ Details

Name:	wpc_OccupancyRate
Namespace Prefix:	wpc_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Other Business Disclosures

+ References

No definition available.

+ Details

Name:	wpc_OtherBusinessDisclosuresAbstract
Namespace Prefix:	wpc_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=wpc_OwnedRealEstateSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

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

- Details

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

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=wpc_InvestmentManagementSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=srt_AffiliatedEntityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	srt_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis=wpc_BuilttoSuitMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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