Common Stock - Additional Information (Detail)					1 Months Ended	12 Months Ended
	Mar. 20, 2015	Dec. 02, 2014 USD ($) $ / shares shares	Feb. 11, 2014 USD ($) $ / shares shares	Jan. 21, 2014	Mar. 31, 2015 USD ($)	Dec. 31, 2015 USD ($) vote $ / shares shares	Dec. 31, 2014 USD ($) $ / shares shares	Dec. 31, 2013 USD ($)
Common Stock Capital Shares Reserved For Future Issuance [Line Items]
Reverse stock split ratio		0.5
Shares of common stock into which warrants are exercisable		871,840
Common stock, shares authorized			200,000,000			200,000,000	200,000,000
Preferred stock, shares authorized			5,000,000			5,000,000	5,000,000
Sale of common stock under securities purchase agreement		1,743,680
Common stock, par value (in dollars per share) | $ / shares						$ 0.001	$ 0.001
Warrant issued, exercise price (in dollars per share) | $ / shares		$ 11.47
Common warrants exercise period		3 years
Net proceeds from offering | $		$ 18,200,000
Commission on gross proceeds (in percent)	3.00%
Proceeds from issuance of common stock | $						$ 12,650,000	$ 70,237,000	$ 0
Common Stock
Common Stock Capital Shares Reserved For Future Issuance [Line Items]
Number of votes per share | vote						1
Issuance of common stock						1,446,781	1,743,680
Common Stock Warrants
Common Stock Capital Shares Reserved For Future Issuance [Line Items]
Common stock, par value (in dollars per share) | $ / shares		$ 0.001
Warrant issued, exercise price (in dollars per share) | $ / shares		$ 15.00
Common Stock
Common Stock Capital Shares Reserved For Future Issuance [Line Items]
Common stock issued with aggregate offering price | $					$ 40,000,000
Initial Public Offering (IPO)
Common Stock Capital Shares Reserved For Future Issuance [Line Items]
Preferred stock, price per share (in dollars per share) | $ / shares			$ 10.00
Issuance of common stock			5,750,000
Proceeds from issuance of common stock | $			$ 50,200,000
Initial Public Offering (IPO) | Common Stock
Common Stock Capital Shares Reserved For Future Issuance [Line Items]
Stock issued related to conversion of preferred stock			8,260,444
Shares of common stock into which warrants are exercisable			30,708
Issuance of common stock						1,446,781	14,010,424
Initial Public Offering (IPO) | Underwriter
Common Stock Capital Shares Reserved For Future Issuance [Line Items]
Issuance of common stock			750,000
Reverse Stock Split
Common Stock Capital Shares Reserved For Future Issuance [Line Items]
Reverse stock split ratio				0.1575