Property and Equipment, net (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 19,633	$ 11,850
Less accumulated depreciation and amortization	(7,803)	(6,450)
Property and equipment, net	11,830	5,400
Depreciation and amortization expense	2,276	1,591	$ 1,490
Laboratory equipment
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	7,932	7,310
Computer equipment and software
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	265	305
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	706	138
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	10,469	1,930
Construction in progress
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 261	$ 2,167