Note 4 - Investments (Details Textual) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Proceeds from Sale and Maturity of Marketable Securities	$ 0		$ 0	$ 440,000
Available-for-sale Securities, Current	826,000		826,000		$ 2,840,000	[1]
Marketable Securities, Realized Gain (Loss)				379,000
Marketable Securities Realized Gain (Loss), Net of Tax				245,000
Marketable Securities, Unrealized Gain (Loss)	452,000	$ 278,000	(1,321,000)	728,000
Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Tax	$ (238,000)	$ (153,000)	$ (728,000)	$ 234,000
Class of Warrant or Right, Number of Securities Called by Warrants or Rights					167,500

[1] The condensed consolidated balance sheet as of December 31, 2014 has been prepared using information from the audited consolidated balance sheet as of that date.