Organization and Description of Business - Additional Information (Detail) $ / shares in Units, $ in Thousands		1 Months Ended		2 Months Ended
	Aug. 16, 2016 $ / shares shares	Sep. 30, 2016 $ / shares shares	Jul. 31, 2016	Sep. 30, 2016 USD ($) $ / shares	Jun. 30, 2017 USD ($)	Dec. 31, 2016 USD ($)
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Accumulated deficit | $					$ 93,673	$ 64,593
Subsidiary, Sale of Stock [Line Items]
Stock split, conversion ratio			0.0689655
IPO [Member]
Subsidiary, Sale of Stock [Line Items]
Stock issued during period, shares, new issues | shares	7,500,000	252,972
Shares issued, price per share (in usd per share) | $ / shares	$ 12.00	$ 12.00		$ 12.00
Proceeds from issuance initial public offering | $				$ 83,600
Common Stock [Member] | IPO [Member]
Subsidiary, Sale of Stock [Line Items]
Convertible preferred stock, shares issued upon conversion | shares	8,577,571