Note 6 - Financial Instruments and Fair Value (Details Textual) - USD ($)	3 Months Ended	12 Months Ended
	Jun. 30, 2015	Dec. 31, 2014	Dec. 31, 2011
Auction Rate Securities [Member]
Available-for-sale Securities	$ 6,650,000	$ 6,905,000
Available-for-sale Securities, Amortized Cost Basis	7,150,000	7,425,000
Available-for-sale Securities, Sold at Par	$ 275,000
Derivative, Basis Spread on Variable Rate	2.25%
Interest Rate Swap [Member] | Cash Flow Hedging [Member]
Derivative Asset, Notional Amount	$ 5,100,000
Asset Impairment Charges			$ 1,000,000
Available-for-sale Debt Securities Gross Unrealized Gain		$ 427,000
Interest Rate Cash Flow Hedge Liability at Fair Value	$ 0