Organization and Description of Business - Additional Information (Details) $ in Thousands				12 Months Ended
	Oct. 31, 2016 USD ($) shares	Oct. 19, 2016 USD ($) shares	Oct. 05, 2016	Dec. 31, 2017	Dec. 31, 2016 USD ($)
Class Of Stock [Line Items]
Reverse stock split description				On October 4, 2016, the Company’s board of directors approved an amendment to the Company’s amended and restated certificate of incorporation to effect a reverse split of the Company’s issued and outstanding common stock at a 1-for- 5.882698 ratio, which was effected on October 5, 2016.
Common stock, reverse stock split ratio			5.882698
Proceeds from stock issuance, net of underwriting discounts and commissions					$ 114,436
Carrying value of convertible preferred stock converted into common stock					$ 97,553
Initial Public Offering
Class Of Stock [Line Items]
Common stock issued | shares		7,238,235
Initial public offering closing date		Oct. 25, 2016
Proceeds from stock issuance, net of underwriting discounts and commissions		$ 110,700
Underwriting discounts and commissions		8,600
Other expenses		$ 3,700
Initial Public Offering | Redeemable Convertible Preferred Stock
Class Of Stock [Line Items]
Number of shares converted into common stock | shares	13,375,333
Carrying value of convertible preferred stock converted into common stock	$ 97,600