Segment Reporting and Geographic Information - Schedule of Revenue from External Customers Attributed to Foreign Countries by Geographic Area (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Revenues	$ 273,784	$ 255,098	$ 232,780
United States [Member]
Segment Reporting Information [Line Items]
Revenues	43,944	36,104	30,876
Taiwan [Member]
Segment Reporting Information [Line Items]
Revenues	45,312	63,079	68,211
South Korea [Member]
Segment Reporting Information [Line Items]
Revenues	51,750	44,180	15,556
Singapore [Member]
Segment Reporting Information [Line Items]
Revenues	14,371	12,775	35,517
Austria [Member]
Segment Reporting Information [Line Items]
Revenues	719	2,601	2,049
Japan [Member]
Segment Reporting Information [Line Items]
Revenues	22,361	18,943	11,875
Germany [Member]
Segment Reporting Information [Line Items]
Revenues	14,913	15,580	9,759
China [Member]
Segment Reporting Information [Line Items]
Revenues	63,243	35,925	33,720
Other Europe [Member]
Segment Reporting Information [Line Items]
Revenues	11,541	21,167	18,720
Other Asia [Member]
Segment Reporting Information [Line Items]
Revenues	$ 5,630	$ 4,744	$ 6,497