Segment Reporting and Geographic Information - (Tables)

6 Months Ended

Jun. 30, 2017

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,
	2017				2016				2017				2016
Systems and software:
Process Control	$	47,711	71	%	$	34,464	55	%	$	91,586	72	%	$	70,922	61	%
Lithography	3,533		5	%	11,480		18	%	3,550		2	%	11,650		10	%
Software	6,895		10	%	7,780		12	%	14,394		11	%	15,202		13	%
Parts	7,348		11	%	5,993		10	%	13,678		11	%	13,153		11	%
Services	1,931		3	%	2,984		5	%	4,889		4	%	6,136		5	%
Total revenue	$	67,418	100	%	$	62,701	100	%	$	128,097	100	%	$	117,063	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,
	2017		2016		2017		2016
United States	$	9,182	$	5,646	$	18,190	$	13,034
Taiwan	20,323		14,535		34,156		36,570
Japan	3,468		3,164		6,677		6,101
China	5,904		10,824		20,005		19,649
South Korea	14,221		2,226		23,751		3,849
Singapore	1,945		14,879		5,211		21,926
Other Asia	1,444		1,674		1,559		2,545
Germany	4,789		4,235		7,869		4,932
Other Europe	6,142		5,518		10,679		8,457
Total revenue	$	67,418	$	62,701	$	128,097	$	117,063

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,
	2017		2016
Customer A	11.2	%	1.6	%
Customer B	6.0	%	13.4	%
Customer C	0.9	%	10.2	%