Income Taxes (Details Textual) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Jan. 01, 2018	Jan. 01, 2017
Tax Credit Carryforward [Line Items]
General business credit	$ 9
Foreign tax credit carry-forwards	2,360	$ 2,958
Cumulative effect adjustment				$ (2,748)
Non-current deferred income tax asset	226	20		222
Valuation allowance, deferred tax asset	2,130
Interest and penalities	80	67	$ 40
Non-current income taxes payable	447	564	545
Reasonably possible change in unrecognized tax benefit	359
Reduction to deferred tax assets and corresponding valuation allowance related to 2017 Tax Act	484	1,780
Reduction to deferred tax assets and corresponding valuation allowance related to 2017 Tax Act	2,264
Transitional toll tax related to 2017 Tax Act	1,209
Net tax benefit related to 2017 Tax Act	54
Net tax benefit related to estimate of the provisions of the 2017 Tax Act		54
Income (loss) before income taxes	(7,667)	(9,938)	(1,970)
Deferred income tax expense (benefit)	(781)	$ (756)	$ 2,406
Federal | Research Tax Credit Carryforward
Tax Credit Carryforward [Line Items]
Unrecognized excess tax benefit	4,707
State Tax Authority
Tax Credit Carryforward [Line Items]
Unrecognized excess tax benefit	251
State Tax Authority | Research Tax Credit Carryforward
Tax Credit Carryforward [Line Items]
Unrecognized excess tax benefit	$ 3,518
Accounting Standards Update 2016-09 | Deferred Tax Assets, Tax Credit Carryforwards And Operating Loss Carryforwards
Tax Credit Carryforward [Line Items]
Cumulative effect adjustment					$ 1,117
Difference between Revenue Guidance in Effect before and after Topic 606 | Accounting Standards Update 2014-09
Tax Credit Carryforward [Line Items]
Non-current deferred income tax asset				$ 202