Consolidated and Combined Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Statement of Comprehensive Income [Abstract]
NET INCOME (LOSS)	$ 26,382	$ (77,991)	$ 45,619	$ (60,332)
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Change in fair value of derivative financial instruments	5,142	0	24,453	0
Reclassification of net loss on derivative financial instruments from accumulated other comprehensive income into interest expense	24	0	1,473	0
Other comprehensive income	(5,166)	0	(25,926)	0
COMPREHENSIVE INCOME (LOSS)	31,548	(77,991)	71,545	(60,332)
Net (income) loss attributable to redeemable noncontrolling interests	3,552	(8,160)	6,532	(2,481)
Other comprehensive income attributable to redeemable noncontrolling interests	(696)	0	(3,406)	0
Net loss attributable to noncontrolling interests	0	0	127	0
COMPREHENSIVE INCOME (LOSS) ATTRIBUTABLE TO JBG SMITH PROPERTIES	$ 27,300	$ (69,831)	$ 61,734	$ (57,851)