Organization and Basis of Presentation - Additional Information (Detail)	1 Months Ended	12 Months Ended
	Jul. 31, 2013 USD ($) $ / shares shares	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Date of incorporation		Jul. 13, 2005
Accumulated deficit		$ (120,899,011)	$ (96,750,385)
Cash, cash equivalents and marketable securities		36,500,000
Working capital		$ 34,500,000
Reverse stock split of outstanding common stock		1-for-8.25
Reverse stock split of outstanding common stock ratio	0.12
Common stock issued in initial public offering (IPO) | shares	6,000,000
Initial public offering of common stock, price per share | $ / shares	$ 11.00
Net proceeds from initial public offering (IPO)	$ 58,600,000