Segment Reporting (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Segment Reporting Information [Line Items]
Revenues	$ 62,701	$ 59,466	$ 117,063	$ 112,036
Concentration Risk, Percentage			13.40%	8.10%
Process Control Revenue [Member]
Segment Reporting Information [Line Items]
Revenues	34,464	41,870	$ 70,922	$ 77,931
Lithography Revenue [Domain]
Segment Reporting Information [Line Items]
Revenues	11,480	3,826	11,650	3,847
Software [Domain]
Segment Reporting Information [Line Items]
Revenues	7,780	5,142	15,202	12,936
Sales Revenue, Goods, Net [Member]
Segment Reporting Information [Line Items]
Revenues	5,993	5,796	13,153	11,451
Sales Revenue, Services, Net [Member]
Segment Reporting Information [Line Items]
Revenues	2,984	2,832	6,136	5,871
Sales Revenue, Segment [Member]
Segment Reporting Information [Line Items]
Revenues	$ 62,701	$ 59,466	$ 117,063	$ 112,036
Sales [Member] | Percentage of Process Control Revenue [Member]
Segment Reporting Information [Line Items]
Concentration Risk, Percentage	55.00%	70.00%	61.00%	70.00%
Sales [Member] | Percentage of Lithography Revenue [Member] [Domain]
Segment Reporting Information [Line Items]
Concentration Risk, Percentage	18.00%	6.00%	10.00%	3.00%
Sales [Member] | Percentage of Software Revenue [Domain]
Segment Reporting Information [Line Items]
Concentration Risk, Percentage	12.00%	9.00%	13.00%	12.00%
Sales [Member] | Percentage of Parts [Member]
Segment Reporting Information [Line Items]
Concentration Risk, Percentage	10.00%	10.00%	11.00%	10.00%
Sales [Member] | Percentage of Service [Member]
Segment Reporting Information [Line Items]
Concentration Risk, Percentage	5.00%	5.00%	5.00%	5.00%
Sales [Member] | Percentage of Total Revenue [Member]
Segment Reporting Information [Line Items]
Concentration Risk, Percentage	100.00%	100.00%	100.00%	100.00%
UNITED STATES
Segment Reporting Information [Line Items]
Revenues	$ 5,646	$ 11,773	$ 13,034	$ 29,420
TAIWAN, PROVINCE OF CHINA
Segment Reporting Information [Line Items]
Revenues	14,535	16,259	36,570	29,588
JAPAN
Segment Reporting Information [Line Items]
Revenues	3,164	3,918	6,101	5,232
CHINA
Segment Reporting Information [Line Items]
Revenues	10,824	858	19,649	6,945
South Korea [Domain]
Segment Reporting Information [Line Items]
Revenues	2,226	6,709	3,849	10,240
SINGAPORE
Segment Reporting Information [Line Items]
Revenues	14,879	8,541	21,926	10,280
Asia [Member]
Segment Reporting Information [Line Items]
Revenues	1,674	818	2,545	857
GERMANY
Segment Reporting Information [Line Items]
Revenues	4,235	8,970	4,932	16,025
Other Europe [Domain]
Segment Reporting Information [Line Items]
Revenues	5,518	1,620	8,457	3,449
Sales [Member]
Segment Reporting Information [Line Items]
Revenues	$ 62,701	$ 59,466	$ 117,063	$ 112,036