Consolidated Statements of Income and Comprehensive Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Income Statement [Abstract]
Product revenue	$ 80,397	$ 75,006	$ 155,367	$ 149,623
Service revenue	9,985	0	19,474	0
Total revenue	90,382	75,006	174,841	149,623
Product cost of goods sold	37,856	29,865	72,688	59,603
Service costs	3,395	0	6,804	0
Cost of goods sold	41,251		79,492
Gross profit	49,131	45,141	95,349	90,020
Operating expenses:
Selling expenses	22,004	23,806	43,944	48,610
General and administrative expenses	21,573	18,866	44,014	38,229
Selling, General and Administrative Expense	43,577	42,672	87,958	86,839
Gain on sale of property	0	(5,422)	0	(5,422)
Operating expenses	43,577	37,250	87,958	81,417
Operating income	5,554	7,891	7,391	8,603
Interest expense	(264)	(166)	(504)	(260)
Other (expense) income, net	(777)	(115)	(490)	110
Income before income taxes	4,513	7,610	6,397	8,453
Income tax expense	$ 1,319	$ 337	$ 1,967	$ 323
Income per share of common stock:
Basic income per share of common stock	$ 0.36	$ 0.82	$ 0.50	$ 0.92
Diluted income per share of common stock	$ 0.35	$ 0.80	$ 0.48	$ 0.89
Weighted average shares outstanding:
Basic weighted average shares outstanding	8,903	8,853	8,896	8,843
Effect of dilutive securities outstanding	314	245	304	252
Diluted weighted average shares outstanding	9,217	9,098	9,200	9,095
Comprehensive income:
Net income	$ 3,194	$ 7,273	$ 4,430	$ 8,130
Adjustment for foreign currency translation	22	729	(1,461)	802
Net comprehensive income	$ 3,216	$ 8,002	$ 2,969	$ 8,932