Stockholders' Equity - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended			3 Months Ended	9 Months Ended		1 Months Ended	9 Months Ended		3 Months Ended	9 Months Ended		3 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013	Sep. 30, 2014 Maximum	Sep. 30, 2014 Employee Stock Option	Sep. 30, 2014 Restricted Stock Outstanding	Jan. 31, 2014 2011 Plan	Sep. 30, 2014 2011 Plan	Sep. 30, 2014 2011 Plan Employee Stock Option	Sep. 30, 2014 Employee Stock Purchase Plan	Sep. 30, 2014 Employee Stock Purchase Plan	Jan. 02, 2014 Employee Stock Purchase Plan	Sep. 30, 2014 Employee Stock Purchase Plan Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based payment award, award vesting period			1 year					4 years			4 years
Percentage of option vesting during first year											25.00%
Vested option expiring period										10 years
Vested but unexercised option expiring period										3 months
Annual increase in shares reserved for equity awards, percentage of outstanding shares						4.00%
Annual Increase in number of shares reserved for equity awards						3,840,000
Additional shares authorized for equity awards			3,279,000				0	2,845,000	3,300,000
Number of shares converted								1
Common stock, par value	$ 0.0001		$ 0.0001		$ 0.0001
Weighted average grant-date fair value of stock options granted	$ 1.53	$ 4.86	$ 1.96	$ 3.03
Percentage of payroll deductions												10.00%
Percentage of purchase price of the shares on each purchase date is equal to the fair market value												85.00%
Share issued under employee stock purchase plan													1,104,000		1,500,000
Percentage of outstanding common stock shares												1.00%
Additional Shares reserved														800,000
Shares available for future issuance												2,097,000	2,097,000