Agreements and Transactions with Related Parties - Personnel, Overhead Costs, Organization and Offering (Details)	Jun. 30, 2018	Dec. 31, 2017
CPA REITs
Reimbursed Costs
Personnel and overhead reimbursement (percentage)	1.00%	2.00%

The percentage threshold for personnel and overhead reimbursement chargeable by the advisor for personnel cost. Personnel expenses excludes costs related to the advisor’s legal transaction group allocated. The threshold is based on pro rata revenue.

No definition available.

Name:	wpc_PersonnelandOverheadReimbursementPercentage
Namespace Prefix:	wpc_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant