Consolidated Statements of Operations and Comprehensive Income - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenue	$ 105,555	$ 113,420	$ 103,379
Operating expenses:
Cost of product revenue	31,280	27,364	24,027
Research & development	18,190	18,787	10,732
Selling, general & administrative	34,336	21,540	18,013
Total operating expenses	83,806	67,691	52,772
Income from operations	21,749	45,729	50,607
Interest and other income, net	1,458	473	263
Income before income taxes	23,207	46,202	50,870
Provision for income taxes	4,485	14,386	18,323
Net income	$ 18,722	$ 31,816	$ 32,547
Basic net income per share:
Basic net income per share (in dollars per share)	$ 1.30	$ 2.18	$ 2.22
Basic weighted average common shares outstanding (in shares)	14,442	14,575	14,682
Diluted net income per share:
Net income (in dollars per share)	$ 1.27	$ 2.11	$ 2.15
Diluted weighted average common shares outstanding (in shares)	14,689	15,068	15,116
Net income	$ 18,722	$ 31,816	$ 32,547
Foreign currency translation adjustment	(742)	2,533	(668)
Comprehensive income	17,980	34,349	31,879
Product [Member]
Revenue	105,531	107,783	102,932
Service [Member]
Revenue	$ 24	$ 5,637	$ 447