Income Taxes (Details Textual) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Jan. 01, 2017
Tax Credit Carryforward [Line Items]
Deferred Tax Assets, Tax Credit Carryforwards, General Business	$ 9
Foreign tax credit carry-forwards	2,958	$ 754
Income (loss) before income taxes	(9,938)	(1,970)	$ 2,666
Valuation allowance, deferred tax asset, change in amount	4,447
Valuation allowance, amount	16,014	11,567
Change in valuation allowance	3,330	7,425	1,392
Federal
Tax Credit Carryforward [Line Items]
Income (loss) before income taxes	(13,271)	(7,775)	(570)
Federal | Research Tax Credit Carryforward
Tax Credit Carryforward [Line Items]
Tax credit carryforward, amount	4,329
State Tax Authority
Tax Credit Carryforward [Line Items]
Tax credit carryforward, amount	243
Change in valuation allowance	3,330
State Tax Authority | Research Tax Credit Carryforward
Tax Credit Carryforward [Line Items]
Tax credit carryforward, amount	3,501
Foreign Tax Authority
Tax Credit Carryforward [Line Items]
Income (loss) before income taxes	$ 3,333	$ 5,805	$ 3,236
Accounting Standards Update 2016-09 [Member] | Deferred Tax Assets, Tax Credit Carryforwards And Operating Loss Carryforwards [Member]
Tax Credit Carryforward [Line Items]
Cumulative Effect of New Accounting Principle in Period of Adoption				$ 1,117