Note 3 - Investment in Common Stock Warrants (Details) - USD ($)		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014
Warrant [Member]
Beginning balance			$ 350,000
Gain on investment in common stock warrants	[1]		30,000
Fair value of warrants exercised			$ (380,000)
Ending balance
Beginning balance		$ 2,840,000
Gain on investment in common stock warrants			$ (30,000)
Ending balance		$ 656,000	$ 2,840,000

[1] Amounts are recognized in other income on the accompanying consolidated statement of income.