Redeemable Noncontrolling Interests - Summary of the Activity of Redeemable Noncontrolling Interests (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Temporary Equity
Balance as of the beginning of the period	$ 499,083	$ 574,228	$ 612,758	$ 558,140
OP Unit redemptions	(4,796)		(40,674)	(57,318)
LTIP Units issued in lieu of cash bonuses (1)			4,066	3,954
Net income (loss) attributable to redeemable noncontrolling interests	(2,212)	1,172	(445)	4,271
Other comprehensive income (loss)	309	(803)	(3,446)	(3,689)
Distributions	(3,723)	(3,831)	(7,505)	(7,670)
Share-based compensation expense	14,496	14,320	51,742	45,937
Adjustment to redemption value	(12,236)	1,446	(125,575)	42,907
Balance as of the end of the period	490,921	586,532	490,921	586,532
JBG Smith, LP
Temporary Equity
Balance as of the beginning of the period	493,067	568,242	606,699	552,159
OP Unit redemptions	(4,796)		(40,674)	(57,318)
LTIP Units issued in lieu of cash bonuses (1)			4,066	3,954
Net income (loss) attributable to redeemable noncontrolling interests	(2,176)	1,172	(366)	4,266
Other comprehensive income (loss)	309	(803)	(3,446)	(3,689)
Distributions	(3,723)	(3,831)	(7,505)	(7,670)
Share-based compensation expense	14,496	14,320	51,742	45,937
Adjustment to redemption value	(14,012)	1,446	(127,351)	42,907
Balance as of the end of the period	483,165	580,546	483,165	580,546
Consolidated Real Estate Venture
Temporary Equity
Balance as of the beginning of the period	6,016	5,986	6,059	5,981
Net income (loss) attributable to redeemable noncontrolling interests	(36)		(79)	5
Adjustment to redemption value	1,776		1,776
Balance as of the end of the period	$ 7,756	$ 5,986	$ 7,756	$ 5,986