Segment Reporting and Geographic Information - Schedule of Revenue from External Customers Attributed to Foreign Countries by Geographic Area (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Revenues	$ 60,081	$ 66,920	$ 67,418	$ 60,679	$ 54,076	$ 61,641	$ 62,701	$ 54,362	$ 255,098	$ 232,780	$ 221,690
United States [Member]
Segment Reporting Information [Line Items]
Revenues									36,104	30,876	46,778
Taiwan [Member]
Segment Reporting Information [Line Items]
Revenues									63,079	68,211	55,548
South Korea [Member]
Segment Reporting Information [Line Items]
Revenues									44,180	15,556	14,221
Singapore [Member]
Segment Reporting Information [Line Items]
Revenues									12,775	35,517	27,310
Austria [Member]
Segment Reporting Information [Line Items]
Revenues									2,601	2,049	3,557
Japan [Member]
Segment Reporting Information [Line Items]
Revenues									18,943	11,875	13,216
Germany [Member]
Segment Reporting Information [Line Items]
Revenues									15,580	9,759	29,378
China [Member]
Segment Reporting Information [Line Items]
Revenues									35,925	33,720	17,152
Other Europe [Member]
Segment Reporting Information [Line Items]
Revenues									21,167	18,720	11,403
Other Asia [Member]
Segment Reporting Information [Line Items]
Revenues									$ 4,744	$ 6,497	$ 3,127