Consolidated Statements of Income (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Revenues	$ 34,044	$ 30,637	$ 100,142	$ 90,565
Cost of goods sold	17,003	15,742	51,757	47,168
Gross profit	17,041	14,895	48,385	43,397
Operating expenses:
Selling	1,530	1,301	4,596	4,208
General and administrative	3,651	3,164	10,952	10,033
Research and development	1,147	753	3,229	2,569
Operating Expenses, Total	6,328	5,218	18,777	16,810
Operating income	10,713	9,677	29,608	26,587
Interest income	310	411	1,005	1,060
Other income, net				2
Nonoperating Income (Expense), Total	310	411	1,005	1,062
Income before provision for income taxes	11,023	10,088	30,613	27,649
Provision for income taxes	(3,350)	(2,829)	(9,800)	(8,914)
Net income	$ 7,673	$ 7,259	$ 20,813	$ 18,735
Net income per basic share	$ 3.82	$ 3.60	$ 10.33	$ 9.30
Weighted average basic shares outstanding	2,007	2,014	2,014	2,015
Net income per diluted share	$ 3.81	$ 3.59	$ 10.31	$ 9.24
Weighted average diluted shares outstanding	2,016	2,022	2,019	2,028
Dividends per common share	$ 0.64	$ 0.56	$ 1.76	$ 1.54