Consolidated Statements of Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Income Statement [Abstract]
Revenues	$ 38,504	$ 36,215
Cost of goods sold	19,873	18,650
Gross profit	18,631	17,565
Operating expenses:
Selling	1,748	1,735
General and administrative	4,017	3,949
Research and development	1,539	1,416
Operating Expenses, Total	7,304	7,100
Operating income	11,327	10,465
Interest income	148	123
Other income (expense), net	1	(345)
Nonoperating Income	149	(222)
Income before provision for income taxes	11,476	10,243
Provision for income taxes	(1,526)	(3,298)
Net income	$ 9,950	$ 6,945
Net income per basic share	$ 5.42	$ 3.81
Weighted average basic shares outstanding	1,835	1,823
Net income per diluted share	$ 5.36	$ 3.74
Weighted average diluted shares outstanding	1,855	1,857
Dividends per common share	$ 1.05	$ 0.9