Stock-Based Compensation - Additional Information (Detail) (USD $)	9 Months Ended		3 Months Ended	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014 Consultant	Sep. 30, 2014 Consultant
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost	$ 5,063,000
Unvested option	1,103,474
Unrecognized compensation cost, recognition period	2 years
Weighted-average grant-date fair values of options granted	$ 10.75	$ 3.17
Common stock options granted, shares			3,873	8,966
Fair market value of shares			$ 50,000	$ 100,000
Agreement end date				2014-10