Note 4 - Investments (Details Textual) - USD ($)	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Proceeds from Sale and Maturity of Marketable Securities	$ 0		$ 0	$ 440,000	$ 440,000
Available-for-sale Securities, Current	1,495,000		1,495,000		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)	(541,000)	$ 563,000	(869,000)	1,005,000
Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Tax	$ (285,000)	$ 232,000	$ (490,000)	$ 387,000
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.