Note 6 - Instruments and Risk Management (Details Textual)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Oct. 01, 2013
Derivative, Swaption Interest Rate			6.27%
Foreign Exchange Forward [Member]
Derivative, Number of Instruments Held, Total	0	0
Foreign Exchange Forward [Member] | Maximum [Member]
Derivative, Term of Contract	1 year
Interest Rate Swap [Member]
Derivative, Term of Contract	10 years
Designated as Hedging Instrument [Member]
Derivative, Number of Instruments Held, Total	0	0