Redeemable Noncontrolling Interests - Summary of the Activity of Redeemable Noncontrolling Interests (Details) - USD ($) $ in Thousands		9 Months Ended
		Sep. 30, 2017	Sep. 30, 2016	Jul. 18, 2017
Temporary Equity
Beginning Balance		$ 0
OP Units issued	[1]	96,632	$ 0
Net loss attributable to redeemable noncontrolling interests		(2,481)
Share-based compensation expense		15,799
Adjustment to record redeemable noncontrolling interest at redemption value	[1]	97,084	$ 0
Ending Balance		$ 567,001
Vesting period (in years)		5 years
Vornado
Temporary Equity
OP Units issued		$ 96,632
JBG Companies
Temporary Equity
OP Units issued		$ 359,967
Portion of consideration attributable to performance of future services				$ 110,591
OP Units
Temporary Equity
Portion of consideration attributable to performance of future services				$ 110,600
OP Units | Minimum
Temporary Equity
Vesting period (in years)		12 years
OP Units | Maximum
Temporary Equity
Vesting period (in years)		60 months

[1] See Note 3 for information about assets, liabilities and noncontrolling interests acquired in the Formation Transaction.