Fair Value Measurement - Schedule of Aggregate Fair Value of The Company's Series B Preferred Stock Tranche Right Liability (Detail) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Schedule Of Aggregate fair value of the Companys series B preferred stock tranche right liability [Line Items]
Balance as of December 31, 2019	$ 300
Exercise of series B preferred stock tranche right	300	$ 0
Series B Redeemable Convertible Preferred Stock [Member]
Schedule Of Aggregate fair value of the Companys series B preferred stock tranche right liability [Line Items]
Balance as of June 30, 2020	300
Series B Redeemable Convertible Preferred Stock [Member] | Fair Value, Inputs, Level 3 [Member]
Schedule Of Aggregate fair value of the Companys series B preferred stock tranche right liability [Line Items]
Balance as of December 31, 2019	300
Exercise of series B preferred stock tranche right	(300)
Balance as of June 30, 2020	$ 0