Description of Business - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	12 Months Ended
	May 31, 2015	Dec. 31, 2016	Dec. 31, 2015
Description Of Business [Line Items]
Place of incorporation		Arizona
Year of incorporation		2002
Place of reincorporation		Delaware
Date of reincorporation		2015-03
Reverse split of issued and outstanding common stock		one-for-four
Proceeds from issuance of common stock upon IPO			$ 68,227
Convertible preferred stock, conversion basis		At the closing of the IPO, all of the outstanding shares of convertible preferred stock and redeemable convertible preferred stock were automatically converted into 32,972,793 shares of common stock.
Converted common stock	32,972,793
Preferred stock, outstanding	0
Common stock, authorized	400,000,000	400,000,000	400,000,000
Preferred stock, authorized	20,000,000
Common stock, par value	$ 0.001	$ 0.001	$ 0.001
Preferred stock, par value	$ 0.001
IPO [Member]
Description Of Business [Line Items]
Common stock, issued and sold	8,528,306
Common stock issued price per share	$ 8.00
Proceeds from issuance of common stock upon IPO	$ 58,400
Underwriting discounts and commissions	4,800
Offering expenses	$ 5,000