Component of Accrued Expenses (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Accrued Liabilities [Line Items]
Clinical consulting services	$ 2,342	$ 2,331
Preclinical services	2,693	3,976
Employee compensation	1,446	1,453
Professional services	488	317
Payroll taxes and benefits	646	289
Manufacturing services	1,116	253
Accrued vacation	294	221
Other consulting services	28	66
Accrued rent	56
Total	$ 9,109	$ 8,906