SCHEDULE II - VALUATION AND QUALIFYING ACCOUNTS (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Allowance for doubtful accounts
Schedule of Valuation and Qualifying Accounts [Roll Forward]
Balance at Beginning of Year	$ 582	$ 463
Additions Charged to Costs and Expenses	543	351
Additions Charged to other Accounts	0	0
Deductions	(355)	(232)
Balance at End of Year	770	582
Allowance for obsolete inventories
Schedule of Valuation and Qualifying Accounts [Roll Forward]
Balance at Beginning of Year	566	381
Additions Charged to Costs and Expenses	710	714
Additions Charged to other Accounts	0	0
Deductions	(752)	(529)
Balance at End of Year	524	566
Valuation allowance for deferred tax assets
Schedule of Valuation and Qualifying Accounts [Roll Forward]
Balance at Beginning of Year	11,436	8,458
Additions Charged to Costs and Expenses	1,357	3,549
Additions Charged to other Accounts	0	0
Deductions	0	(571)
Balance at End of Year	12,793	11,436
Reserve for sales returns
Schedule of Valuation and Qualifying Accounts [Roll Forward]
Balance at Beginning of Year	117	129
Additions Charged to Costs and Expenses	1,188	1,277
Additions Charged to other Accounts	0	0
Deductions	(1,229)	(1,289)
Balance at End of Year	$ 76	$ 117