Document and Entity Information - USD ($)	6 Months Ended
	Jun. 30, 2018	Aug. 03, 2018	Jun. 30, 2017
Document And Entity Information [Abstract]
Entity Registrant Name	JBG SMITH PROPERTIES
Entity Central Index Key	0001689796
Current Fiscal Year End Date	--06-30
Entity Filer Category	Non-accelerated Filer
Document Type	10-Q
Document Period End Date	Jun. 30, 2018
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	Q2
Amendment Flag	false
Entity Common Stock, Shares Outstanding		120,328,976
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$ 0