Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2018	May 11, 2018
Document Information [Line Items]
Document Type	10-Q
Document Period End Date	Mar. 31, 2018
Amendment Flag	false
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	Q1
Current Fiscal Year End Date	--12-31
Entity Central Index Key	0001558235
Entity Filer Category	Non-accelerated Filer
Entity Registrant Name	Corporate Property Associates 18 Global Incorporated
Class A
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		113,211,400
Class C
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		31,680,530