Property, Plant and Equipment, Net - Property, Plant and Equipment, Net (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 34,940	$ 10,102
Less: Accumulated depreciation	(3,008)	(2,245)
Property and equipment, net	31,932	7,857
Manufacturing equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	2,082	1,689
Laboratory equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	3,602	2,537
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Property and equipment, gross	1,209	808
Software and computer equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	1,932	1,732
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment, gross	1,887	641
Construction-in-progress
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 24,228	$ 2,695