Stockholders Equity - Additional Information (Detail) (USD $)	0 Months Ended		12 Months Ended
	Mar. 20, 2014	Jan. 13, 2014	Dec. 31, 2014	Dec. 31, 2013
Stockholders' Equity Note [Abstract]
Common stock reserved for issuance upon exercise of outstanding common stock options and vesting of restricted stock units			2,373,017
Common stock reserved for future grants of stock options			1,772,529
Common stock reserved for future exercise of outstanding warrants			267,826
Issue of common stock shares	2,875,000	3,047,500
Number of shares sold pursuant to full exercise of underwriter's over allotment option	375,000	397,500
Exercise price of shares	$ 13.00	$ 10.65
Gross proceeds from public offering	$ 4,900,000	$ 32,500,000	$ 34,957,000
Net proceeds from public offering	4,400,000	30,300,000
Underwriting of Discount and expense	319,000	2,300,000
Estimated costs of public offering	$ 148,000
Outstanding warrants to purchase common stock			267,826	267,826
Outstanding warrants to purchase common stock at exercise price per share			$ 3.65	$ 3.65
Warrants exercisable date of issuance			10 years
Repurchase of company shares			0	0