Schedule II - Valuation and Qualifying Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Allowance for Doubtful Accounts Receivable:
Allowance for Doubtful Accounts Receivable, beginning balance	$ 102	$ 366
Allowance for Doubtful Accounts Receivable, charged to operations	68	42
Allowance for Doubtful Accounts Receivable, credited to operations	0	(295)
Allowance for Doubtful Accounts Receivable, written off	0	0
Allowance for Doubtful Accounts Receivable, effect of exchange rate changes	0	(11)
Allowance for Doubtful Accounts Receivable, ending balance	170	102
Inventory reserve:
Inventory reserve, beginning balance	399	826
Inventory reserve, charged to operations	40	60
Inventory reserve, credited to operations	0	(458)
Inventory reserve, written off	0	0
Inventory reserve, effect of exchange rate changes	7	(29)
Inventory reserve, ending balance	446	399
Deferred Tax Valuation Allowance:
Deferred tax valuation allowance, beginning balance	1,478	1,703
Deferred tax valuation allowance, charged to operations	0	0
Deferred tax valuation allowance, charged to additional paid-in capital and other comprehensive income	0	0
Deferred tax valuation allowance, credited to additional paid-in capital and other comprehensive income	(114)	(225)
Deferred tax valuation allowance, other adjustments	0	0
Deferred tax valuation allowance, ending balance	$ 1,364	$ 1,478