SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Restricted Cash, A/R, Inventories, Property and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Property and Equipment
Accumulated Depreciation	$ (27,700)	$ (26,313)
Total Property and Equipment, net	10,178	10,176
Restricted Cash
Outstanding letters of credit	0
Restricted cash	467	306
Accounts Receivable and Allowance for Doubtful Accounts
Accounts Receivable Allowances	222	209
Inventories
Raw Materials	16,769	13,870
Work in Process	1,015	3,112
Finished Goods	332	2,389
Reserves	(1,112)	(844)
Total	17,004	18,527
Land
Property and Equipment
Property and equipment	360	360
Building and Leasehold Improvements
Property and Equipment
Property and equipment	$ 9,184	8,827
Buildings
Property and Equipment
Estimated useful lives	39 years
Leasehold improvements | Minimum
Property and Equipment
Estimated useful lives	3 years
Leasehold improvements | Maximum
Property and Equipment
Estimated useful lives	15 years
Manufacturing equipment
Property and Equipment
Property and equipment	$ 21,260	21,267
Manufacturing equipment | Minimum
Property and Equipment
Estimated useful lives	3 years
Manufacturing equipment | Maximum
Property and Equipment
Estimated useful lives	7 years
Office and other equipment
Property and Equipment
Property and equipment	$ 7,074	$ 6,035
Office and other equipment | Minimum
Property and Equipment
Estimated useful lives	3 years
Office and other equipment | Maximum
Property and Equipment
Estimated useful lives	7 years