Stock-Based Compensation - Additional Information (Detail) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2007
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options granted expiration term			10 years
Stock options exercised			0	0
Shares reserved, description			Shares reserved automatically increase each year by a number equal to the lesser of: (i) 15,000 shares; (ii) 1% of the outstanding shares of common stock on the last day of the immediately preceding fiscal year; or (iii) such lesser amount as determined by the Board.
Percentage of employee compensation for purchase of common stock under ESPP			Cannot exceed 15%
Common stock fair market value, percentage			85.00%
Employee stock purchase plan offering period			6 months
Shares issued under ESPP			21,604
Stock Options, Granted			649,000
Stock-based compensation expense	$ 546,366	$ 231,321	$ 1,059,671	$ 486,420
Unamortized compensation cost	$ 1,300,000		$ 1,300,000
Unamortized compensation cost, vesting period			1 year
Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common Stock reserved for future issuance	209,349		209,349			300,000
2013 Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common Stock reserved for future issuance					2,500,000
Stock option available for future grant	1,710,825		1,710,825
2013 Plan | Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock option, vesting period			3 years
2013 Plan | Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock option, vesting period			4 years