Property and Equipment - Schedule of Property and Equipment (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Property and equipment, Gross	$ 1,397	$ 1,561
Less: accumulated depreciation	(275)	(431)
Property and equipment, net	$ 1,122	1,130
Office Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, Useful lives	5 years
Property and equipment, Gross	$ 357	407
Computer Hardware and Software [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, Gross	$ 96	263
Computer Hardware and Software [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, Useful lives	3 years
Computer Hardware and Software [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, Useful lives	7 years
Laboratory Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, Useful lives	5 years
Property and equipment, Gross	$ 499	446
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, Useful lives	7 years
Property and equipment, Gross	$ 445	$ 445