Segment Reporting and Geographic Information - (Tables)

6 Months Ended

Jun. 30, 2016

Segment Reporting and Geographic Information [Abstract]

Schedule of revenue from external customers by Products and Services [Table Text Block]

The following table lists the different sources of revenue:

	Three Months Ended								Six Months Ended
	June 30,								June 30,
	2016				2015				2016				2015
Systems and Software:
Process Control	$	34,464	55	%	$	41,870	70	%	$	70,922	61	%	$	77,931	70	%
Lithography	11,480		18	%	3,826		6	%	11,650		10	%	3,847		3	%
Software	7,780		12	%	5,142		9	%	15,202		13	%	12,936		12	%
Parts	5,993		10	%	5,796		10	%	13,153		11	%	11,451		10	%
Services	2,984		5	%	2,832		5	%	6,136		5	%	5,871		5	%
Total revenue	$	62,701	100	%	$	59,466	100	%	$	117,063	100	%	$	112,036	100	%

Schedule of Revenue from External Customers Attributed to Foreign Countries by Geographic Area [Table Text Block]

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

	Three Months Ended				Six Months Ended
	June 30,				June 30,
	2016		2015		2016		2015
United States	$	5,646	$	11,773	$	13,034	$	29,420
Taiwan	14,535		16,259		36,570		29,588
Japan	3,164		3,918		6,101		5,232
China	10,824		858		19,649		6,945
South Korea	2,226		6,709		3,849		10,240
Singapore	14,879		8,541		21,926		10,280
Other Asia	1,674		818		2,545		857
Germany	4,235		8,970		4,932		16,025
Other Europe	5,518		1,620		8,457		3,449
Total revenue	$	62,701	$	59,466	$	117,063	$	112,036

Schedule of Revenue by Major Customers by Reporting Segments [Table Text Block]

The following customers each accounted for more than 10% of total revenues for the indicated periods.

	Six Months Ended
	June 30,
	2016		2015
Customer A	13.4	%	8.1	%
Customer B	10.2	%	6.4	%