Formation and Business of the Company - Additional Information (Detail) - USD ($) $ in Thousands	1 Months Ended	9 Months Ended
	Jan. 31, 2015	Sep. 30, 2015
Public Offering [Line Items]
Business incorporated date		Dec. 10, 2008
Proceeds from issuance of common stock in secondary offering, net of issuance costs		$ 80,208
Secondary Offering [Member]
Public Offering [Line Items]
Secondary public offering shares of common stock issued	4,999,999
Proceeds from issuance of common stock in secondary offering, net of issuance costs	$ 80,200