Segments and Major Customers (Details 3) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Major Customer Disclosure
Revenue	$ 61,913	$ 56,915	$ 59,930	$ 63,989	$ 59,947	$ 57,399	$ 58,297	$ 48,384	$ 242,747	$ 224,027	$ 231,201
Property, plant and equipment, net	57,693				44,714				57,693	44,714
South Korea
Major Customer Disclosure
Revenue									3,664	3,583	13,421
USA
Major Customer Disclosure
Revenue									137,614	134,526	129,567
Property, plant and equipment, net	53,200				40,300				53,200	40,300
TAIWAN, PROVINCE OF CHINA
Major Customer Disclosure
Revenue									21,803	24,118	21,749
Japan
Major Customer Disclosure
Revenue									16,862	11,877	23,222
Europe
Major Customer Disclosure
Revenue									7,359	10,262	15,668
Canada
Major Customer Disclosure
Revenue									1,162	3,554	4,960
SINGAPORE
Major Customer Disclosure
Revenue									28,034	21,751	19,140
Asia-Other
Major Customer Disclosure
Revenue									26,249	14,356	$ 3,474
India
Major Customer Disclosure
Property, plant and equipment, net	3,300				3,400				3,300	3,400
Other foreign locations
Major Customer Disclosure
Property, plant and equipment, net	$ 1,200				$ 1,000				$ 1,200	$ 1,000