Net Loss Per Share - Summary of Antidilutive Securities Excluded From Computation Diluted Weighted Average Shares Outstanding (Detail) - shares	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Schedule Of Calculation Of Numerator And Denominator In Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share amount	7,417,186	6,300,712
Unvested Restricted Stock [Member]
Schedule Of Calculation Of Numerator And Denominator In Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share amount	420,541	811,681
Unvested Restricted Stock Units [Member]
Schedule Of Calculation Of Numerator And Denominator In Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share amount	1,878,730	619,240
Employee Stock Purchase Plan [Member]
Schedule Of Calculation Of Numerator And Denominator In Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share amount	76,647	103,471
Options to Purchase Common Stock [Member]
Schedule Of Calculation Of Numerator And Denominator In Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share amount	5,041,268	4,766,320