Preferred Stock and Stockholders' Equity - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands							12 Months Ended
	Feb. 17, 2015	Feb. 09, 2015	Feb. 03, 2015	Jan. 13, 2015	Oct. 29, 2013	Oct. 23, 2013	Dec. 31, 2015	Dec. 31, 2013	Dec. 31, 2014	Apr. 26, 2006
Equity [Line Items]
Shares of authorized capital stock										280,000,000
Common stock, shares authorized							250,000,000		250,000,000	250,000,000
Common stock par value per share							$ 0.001		$ 0.001	$ 0.001
Preferred stock, shares authorized										30,000,000
Preferred stock par value										$ 0.001
Common Stock Shares Sold					16,445,000
Proceeds from issuance of common stock					$ 57,600		$ 94,320	$ 53,880
Common Stock Price Per Share					$ 3.50
License Agreement
Equity [Line Items]
Issuance of common stock in licensing agreement (in shares)				11,722,163			11,722,163
J.P. Morgan Securities Inc.
Equity [Line Items]
Common Stock Price Per Share			$ 8.225			$ 3.29
Stock issued during period	1,500,000	10,000,000	10,000,000		2,145,000	14,300,000
Issuance & sale of common stock in public offering price per share			$ 8.75			$ 3.50
Option granted, exercisable period			30 days			30 days
Option to purchase common stock			1,500,000			2,145,000
Expected net proceeds from issuance of common stock	$ 94,300