Segments and Major Customers (Details 3) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Major Customer Disclosure
Revenue	$ 101,891	$ 99,134	$ 94,720	$ 97,351	$ 97,559	$ 89,855	$ 76,501	$ 72,682	$ 393,096	$ 336,597	$ 296,278
Property, plant and equipment, net	54,303				58,442				54,303	58,442
South Korea
Major Customer Disclosure
Revenue									115,811	129,542	115,486
USA
Major Customer Disclosure
Revenue									165,263	121,209	118,278
Property, plant and equipment, net	47,200				55,000				47,200	55,000
Japan
Major Customer Disclosure
Revenue									23,378	30,215	29,687
Europe
Major Customer Disclosure
Revenue									22,597	16,031	9,616
Canada
Major Customer Disclosure
Revenue									4,373	3,478	214
SINGAPORE
Major Customer Disclosure
Revenue									22,554	17,908	16,312
Asia-Other
Major Customer Disclosure
Revenue									39,120	18,214	$ 6,685
India
Major Customer Disclosure
Property, plant and equipment, net	3,400				1,300				3,400	1,300
Other foreign locations
Major Customer Disclosure
Property, plant and equipment, net	$ 3,700				$ 2,100				$ 3,700	$ 2,100