Segment Reporting and Geographic Information Geographic Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Segment Reporting Information [Line Items]
Revenues	$ 67,418	$ 62,701	$ 128,097	$ 117,063
UNITED STATES
Segment Reporting Information [Line Items]
Revenues	9,182	5,646	18,190	13,034
TAIWAN, PROVINCE OF CHINA
Segment Reporting Information [Line Items]
Revenues	20,323	14,535	34,156	36,570
JAPAN
Segment Reporting Information [Line Items]
Revenues	3,468	3,164	6,677	6,101
CHINA
Segment Reporting Information [Line Items]
Revenues	5,904	10,824	20,005	19,649
South Korea [Domain]
Segment Reporting Information [Line Items]
Revenues	14,221	2,226	23,751	3,849
SINGAPORE
Segment Reporting Information [Line Items]
Revenues	1,945	14,879	5,211	21,926
Asia [Member]
Segment Reporting Information [Line Items]
Revenues	1,444	1,674	1,559	2,545
GERMANY
Segment Reporting Information [Line Items]
Revenues	4,789	4,235	7,869	4,932
Country Other Europe [Member]
Segment Reporting Information [Line Items]
Revenues	6,142	5,518	10,679	8,457
Sales [Member]
Segment Reporting Information [Line Items]
Revenues	$ 67,418	$ 62,701	$ 128,097	$ 117,063