Schedule II - Schedule of Valuation and Qualifying Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Allowance for doubtful accounts and returns
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning Balance	$ 33	$ 42	$ 236
Charges to Revenue/ Expense	30	20	23
Deductions	35	29	217
Ending Balance	28	33	42
Reserve for excess, obsolete, and slow moving inventories
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning Balance	4,212	4,196	5,596
Charges to Revenue/ Expense	814	1,085	1,139
Deductions	1,381	1,069	2,539
Ending Balance	3,645	4,212	4,196
Valuation allowance for deferred tax assets
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning Balance	12,822	10,556	12,537
Charges to Revenue/ Expense	1,568	2,266	3,883
Deductions	0	0	5,864
Ending Balance	$ 14,390	$ 12,822	$ 10,556