Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
ASSETS
Cash and cash equivalents	$ 771	$ 1,102
Treasury bills	5,424	5,248
Available-for-sale securities	2,705	3,677
Trade receivables, less allowance for doubtful accounts of $8 and $10, respectively	754	602
Inventories	1,322	1,330
Other current assets	110	75
Total current assets	11,086	12,034
Property and equipment, net	1,262	1,304
Total assets	12,348	13,338
LIABILITIES AND STOCKHOLDERS' EQUITY
Accounts payable	90	94
Accrued expenses	265	227
Accrued income tax	64	313
Total current liabilities	419	634
Deferred income tax liability	1,110	1,455
Commitments and contingencies
Stockholders' equity
Common stock par value $0.10 per share; authorized 10,000,000 shares; issued and outstanding: 3,393,736 and 3,391,912 shares, respectively	339	339
Additional paid-in capital	1,581	1,575
Retained earnings	7,277	7,113
Accumulated other comprehensive income (unrealized gain on available-for-sale securities, net of income tax)	1,622	2,222
Total stockholders' equity	10,819	11,249
Total liabilities and stockholders' equity	$ 12,348	$ 13,338