Stock-Based Compensation - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended			12 Months Ended			9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013	Dec. 31, 2012 Employee Stock Option Minimum	Dec. 31, 2012 Employee Stock Option Maximum	Dec. 31, 2012 Non-Employee Directors and Consultants	Sep. 30, 2014 Unvested Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 533,092	$ 205,772	$ 1,385,728	$ 768,534
Incentive options, vesting period						4 years	5 years	1 year	5 years
Incentive options, vesting on the first anniversary of the date of grant						20.00%	25.00%
Incentive options, term							10 years
Stock options, outstanding	1,259,317	1,670,688	1,259,317	1,670,688	1,610,988
Number of shares available for future grant	2,824,057		2,824,057
Closing price of common stock	$ 19.91		$ 19.91
Weighted average grant date fair value of share-based awards granted			$ 11.12	$ 4.19
Total fair value of stock options vested			1,023,136	934,280
Total unrecognized compensation cost	$ 4,034,523		$ 4,034,523
Unrecognized compensation cost, weighted average remaining requisite service period			3 years 2 months 12 days
Number of unvested options	689,031		689,031