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		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Segment Reporting Information [Line Items]
Revenues	$ 60,432	$ 66,920	$ 211,004	$ 195,017
United States [Member]
Segment Reporting Information [Line Items]
Revenues	11,476	7,666	29,344	25,856
Taiwan [Member]
Segment Reporting Information [Line Items]
Revenues	10,233	17,300	35,643	49,960
Japan [Member]
Segment Reporting Information [Line Items]
Revenues	4,134	6,268	14,082	12,944
China [Member]
Segment Reporting Information [Line Items]
Revenues	11,547	4,151	52,866	24,156
South Korea [Member]
Segment Reporting Information [Line Items]
Revenues	10,977	10,852	44,581	36,099
Singapore [Member]
Segment Reporting Information [Line Items]
Revenues	4,644	4,664	11,985	9,875
Other Asia [Member]
Segment Reporting Information [Line Items]
Revenues	1,102	1,690	3,520	3,249
Germany [Member]
Segment Reporting Information [Line Items]
Revenues	3,527	4,488	8,668	12,357
Other Europe [Member]
Segment Reporting Information [Line Items]
Revenues	$ 2,792	$ 9,841	$ 10,315	$ 20,521