Property and Equipment (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 17,418		$ 17,418		$ 14,602
Less: accumulated depreciation	(3,489)		(3,489)		(2,402)
Property and equipment, net	13,929		13,929		12,200
Depreciation expense	400	$ 300	1,200	$ 900
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment, gross	3,033		$ 3,033		2,976
Leasehold improvements | Minimum
Property, Plant and Equipment [Line Items]
Useful life (in years)			7 years
Leasehold improvements | Maximum
Property, Plant and Equipment [Line Items]
Useful life (in years)			20 years
Machinery & equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	8,456		$ 8,456		7,853
Machinery & equipment | Minimum
Property, Plant and Equipment [Line Items]
Useful life (in years)			1 year
Machinery & equipment | Maximum
Property, Plant and Equipment [Line Items]
Useful life (in years)			12 years
Furniture
Property, Plant and Equipment [Line Items]
Property and equipment, gross	1,734		$ 1,734		1,698
Furniture | Minimum
Property, Plant and Equipment [Line Items]
Useful life (in years)			1 year
Furniture | Maximum
Property, Plant and Equipment [Line Items]
Useful life (in years)			12 years
Construction in progress
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 4,195		$ 4,195		$ 2,075