Segment Reporting (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Segment Reporting Information [Line Items]
Revenues	$ 54,362	$ 52,570
Concentration Risk, Percentage	26.90%	11.10%
Process Control Revenue [Member]
Segment Reporting Information [Line Items]
Revenues	$ 36,459	$ 36,061
Lithography Revenue [Domain]
Segment Reporting Information [Line Items]
Revenues	170	21
Software [Domain]
Segment Reporting Information [Line Items]
Revenues	7,422	7,794
Sales Revenue, Goods, Net [Member]
Segment Reporting Information [Line Items]
Revenues	7,160	5,655
Sales Revenue, Services, Net [Member]
Segment Reporting Information [Line Items]
Revenues	3,151	3,039
Sales Revenue, Segment [Member]
Segment Reporting Information [Line Items]
Revenues	$ 54,362	$ 52,570
Sales [Member] | Percentage of Process Control Revenue [Member]
Segment Reporting Information [Line Items]
Concentration Risk, Percentage	67.00%	69.00%
Sales [Member] | Percentage of Lithography Revenue [Member] [Domain]
Segment Reporting Information [Line Items]
Concentration Risk, Percentage	0.00%	0.00%
Sales [Member] | Percentage of Software Revenue [Domain]
Segment Reporting Information [Line Items]
Concentration Risk, Percentage	14.00%	15.00%
Sales [Member] | Percentage of Parts [Member]
Segment Reporting Information [Line Items]
Concentration Risk, Percentage	13.00%	10.00%
Sales [Member] | Percentage of Service [Member]
Segment Reporting Information [Line Items]
Concentration Risk, Percentage	6.00%	6.00%
Sales [Member] | Percentage of Total Revenue [Member]
Segment Reporting Information [Line Items]
Concentration Risk, Percentage	100.00%	100.00%
UNITED STATES
Segment Reporting Information [Line Items]
Revenues	$ 7,388	$ 17,648
TAIWAN, PROVINCE OF CHINA
Segment Reporting Information [Line Items]
Revenues	22,035	13,329
JAPAN
Segment Reporting Information [Line Items]
Revenues	2,937	1,314
CHINA
Segment Reporting Information [Line Items]
Revenues	8,825	6,088
South Korea [Domain]
Segment Reporting Information [Line Items]
Revenues	1,623	3,531
SINGAPORE
Segment Reporting Information [Line Items]
Revenues	7,047	1,738
Asia [Member]
Segment Reporting Information [Line Items]
Revenues	871	39
GERMANY
Segment Reporting Information [Line Items]
Revenues	697	7,055
Other Europe [Domain]
Segment Reporting Information [Line Items]
Revenues	2,939	1,828
Sales [Member]
Segment Reporting Information [Line Items]
Revenues	$ 54,362	$ 52,570