Formation and Business of the Company - Additional Information (Detail) - USD ($) $ in Thousands		1 Months Ended		12 Months Ended
	Nov. 04, 2016	Jan. 31, 2015	Mar. 31, 2014	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Public Offering [Line Items]
Business incorporated date				Dec. 10, 2008
Proceeds from issuance of common stock in initial public offering, net of issuance costs			$ 132,100			$ 132,137
Common stock, shares authorized			50,000,000	50,000,000	50,000,000
Convertible preferred stock, shares authorized			5,000,000
Proceeds from issuance of common stock in follow-on offering, net of issuance costs	$ 59,100			$ 59,136	$ 80,209
IPO [Member]
Public Offering [Line Items]
Public offering shares of common stock issued			6,900,000
Secondary Offering [Member]
Public Offering [Line Items]
Public offering shares of common stock issued	5,176,545	4,999,999
Proceeds from issuance of common stock in follow-on offering, net of issuance costs	$ 59,100	$ 80,209