Note 1 - Summary of Significant Accounting Policies (Detail) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Available-for-sale Securities, Fair Value Disclosure	$ 4,854,000	$ 4,355,000
Available-for-sale Securities, Debt Maturities, Next Twelve Months, Fair Value	4,700,000	2,300,000
Available-for-sale Securities, Debt Maturities, Year Two Through Five, Fair Value	200,000	2,100,000
Available-for-sale Securities, Change in Net Unrealized Holding Gain (Loss), Net of Tax	1,000	(20,000)
Sales Returns and Allowances, Goods	22,000	25,000	47,000
Inventory Write-down	57,000	60,000	200,000
Impairment of Long-Lived Assets Held-for-use	0	0	29,000
Unbilled Receivables, Current	77,000	90,000
Standard Product Warranty Accrual	15,000	35,000
Investment Income, Interest	34,000	46,000	141,000
Interest Expense	9,000	24,000	39,000
Advertising Expense	$ 9,000	$ 6,000	$ 9,000
Software [Member] | Minimum [Member]
Property, Plant and Equipment, Useful Life	3 years
Software [Member] | Maximum [Member]
Property, Plant and Equipment, Useful Life	5 years