Formation and Business of the Company - Additional Information (Detail) - USD ($) $ in Thousands	1 Months Ended		12 Months Ended
	Jan. 31, 2015	Mar. 31, 2014	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
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	4,999,999
Proceeds from issuance of common stock in public offering, net of issuance costs	$ 80,209		$ 80,209