Segment Reporting and Geographic Information - (Tables)

12 Months Ended

Dec. 31, 2017

Segment Reporting And Geographic Information [Abstract]

Schedule of Revenue from External Customers by Products and Services

The following table lists the different sources of revenues:

	Year Ended December 31,
	2017				2016				2015
Systems and Software:
Process control	$	177,177	70	%	$	146,652	63	%	$	144,858	66	%
Lithography		14,234	5	%		18,949	8	%		14,519	6	%
Software		25,473	10	%		29,795	13	%		27,291	12	%
Parts		27,143	11	%		25,343	11	%		24,072	11	%
Services		11,071	4	%		12,041	5	%		10,950	5	%
Total revenues	$	255,098	100	%	$	232,780	100	%	$	221,690	100	%

Schedule of Revenue from External Customers Attributed to Foreign Countries by Geographic Area

For geographical reporting, revenues are attributed to the geographic location in which the product is shipped. Revenues by geographic region are as follows:

	Year Ended December 31,
	2017		2016		2015
Revenues from third parties:
United States	$	36,104	$	30,876	$	46,778
Taiwan		63,079		68,211		55,548
South Korea		44,180		15,556		14,221
Singapore		12,775		35,517		27,310
Austria		2,601		2,049		3,557
Japan		18,943		11,875		13,216
Germany		15,580		9,759		29,378
China		35,925		33,720		17,152
Other Europe		21,167		18,720		11,403
Other Asia		4,744		6,497		3,127
Total revenues	$	255,098	$	232,780	$	221,690