Condensed Consolidated Statements Of Operations (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Condensed Consolidated Statements Of Operations [Abstract]
Net sales	$ 1,795	$ 1,543	$ 3,437	$ 3,060
Cost of goods sold	787	658	1,493	1,283
Gross profit	1,008	885	1,944	1,777
Operating expenses:
Selling and marketing	383	349	793	695
General and administrative	248	226	525	479
Research and development	101	118	228	219
Total operating expenses	732	693	1,546	1,393
Operating income	276	192	398	384
Non-operating income:
Interest income	3	1	4	4
Gain on investment securities	0	1	0	1
Other income	3	1	6	3
Total non-operating income	6	3	10	8
Income from continuing operations before income taxes	282	195	408	392
Income taxes	99	78	147	147
Income before discontinued operations	183	117	261	245
Income (loss) from discontinued operations, net of income taxes	0	1	0	(33)
Net income	183	118	261	212
Other comprehensive income (loss):
Change in unrealized value of investments, net of income tax	(508)	(80)	(115)	561
Total comprehensive income (loss)	$ (325)	$ 38	$ 146	$ 773
Net income (loss) per share data:
Net income per share continuing operations	$ 0.05	$ 0.03	$ 0.07	$ 0.07
Net loss per share discontinued operations	$ 0.00	$ 0.00	$ 0.00	$ (0.01)
Net income per share	$ 0.05	$ 0.03	$ 0.07	$ 0.06
Weighted average shares	3,390,785	3,388,241	3,390,752	3,386,016
Diluted
Net income per share continuing operations	$ 0.05	$ 0.03	$ 0.07	$ 0.07
Net loss per share discontinued operations	$ 0.00	$ 0.00	$ 0.00	$ (0.01)
Net income per share	$ 0.05	$ 0.03	$ 0.07	$ 0.06
Weighted average shares	3,407,765	3,405,468	3,407,732	3,405,358
Dividends paid per share	$ 0.04	$ 0.04	$ 0.08	$ 0.08