Preferred Stock Warrants - Additional Information (Detail) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended		6 Months Ended
	Apr. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	May 31, 2016
Class of Warrant or Right [Line Items]
Proceeds from issuance of redeemable convertible preferred stock upon exercise of warrants				$ 0	$ 22,508
Remeasured fair value of warrants	$ 1,000
Reclassification of redeemable convertible preferred stock warrant liability to redeemable convertible preferred stock				0	1,005
Change in fair value of redeemable convertible preferred stock warrant liability		$ 0	$ 0	$ 0	$ 525
Redeemable Convertible Preferred Stock Warrant Liability [Member]
Class of Warrant or Right [Line Items]
Reclassification of redeemable convertible preferred stock warrant liability to redeemable convertible preferred stock	$ 1,000
Option Pricing Model [Member]
Class of Warrant or Right [Line Items]
Percentage of weighted value per share	67.00%
PWERM [Member]
Class of Warrant or Right [Line Items]
Percentage of weighted value per share	33.00%
Series B Redeemable Convertible Preferred Stock [Member]
Class of Warrant or Right [Line Items]
Redeemable convertible preferred stock, shares issued	1,999,998
Proceeds from issuance of redeemable convertible preferred stock upon exercise of warrants	$ 20
Number of redeemable convertible preferred stock expired unexercised						2,000,000