Equipment, Furniture and Leasehold Improvements (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Total equipment, furniture and leasehold improvements	$ 20,157	$ 18,156
Less: accumulated depreciation	(11,236)	(9,603)
Equipment, furniture and leasehold improvements, net	8,921	8,553
Depreciation expense	1,900	1,800
Computer Hardware and Software [Member]
Property, Plant and Equipment [Line Items]
Total equipment, furniture and leasehold improvements	800	693
Lab and Factory Equipment [Member]
Property, Plant and Equipment [Line Items]
Total equipment, furniture and leasehold improvements	17,107	15,678
Furniture, Fixtures and Office Equipment [Member]
Property, Plant and Equipment [Line Items]
Total equipment, furniture and leasehold improvements	48	47
Assets Under Capital Leases [Member]
Property, Plant and Equipment [Line Items]
Total equipment, furniture and leasehold improvements	66	66
Construction in Progress [Member]
Property, Plant and Equipment [Line Items]
Total equipment, furniture and leasehold improvements	2,114	$ 1,672
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Total equipment, furniture and leasehold improvements	$ 22