Property and Equipment, net (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Property, Plant and Equipment [Line Items]
Property and equipment, Gross	$ 1,028		$ 1,028		$ 731
Less: Accumulated depreciation	(335)		(335)		(235)
Property and equipment, Net	693		693		496
Depreciation of property and equipment	56	$ 38	100	$ 116
Computer equipment
Property, Plant and Equipment [Line Items]
Property and equipment, Gross	328		328		329
Office and other equipment
Property, Plant and Equipment [Line Items]
Property and equipment, Gross	222		222		56
Laboratory equipment
Property, Plant and Equipment [Line Items]
Property and equipment, Gross	427		427		346
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment, Gross	$ 51		$ 51		$ 0