Property and Equipment, net (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Property and equipment, Gross	$ 1,310		$ 1,256
Less: Accumulated depreciation	(672)		(627)
Property and equipment, net	638		629
Depreciation	45	$ 58
Computer equipment
Property, Plant and Equipment [Line Items]
Property and equipment, Gross	329		329
Office and other equipment
Property, Plant and Equipment [Line Items]
Property and equipment, Gross	301		301
Laboratory equipment
Property, Plant and Equipment [Line Items]
Property and equipment, Gross	617		563
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment, Gross	$ 63		$ 63