Property and Equipment - Summary of Property and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Property and equipment, total	$ 28,723	$ 17,630
Less accumulated depreciation	(9,378)	(4,922)
Property and equipment, net	19,345	12,707
Furniture and fixtures [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, total	1,035	458
Office equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, total	493	326
Machinery and lab equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, total	19,868	13,220
Leasehold improvements [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, total	$ 7,327	$ 3,625