Note 4 - Fair Value Measurements and Derivative Financial Instruments - Effect of Cash Flow Hedge Accounting on the Company's Statement of Operations (Details) - Interest Expense [Member] - Designated as Hedging Instrument [Member] - Cash Flow Hedging [Member] - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Hedged interest payments	$ (1,594)	$ (1,487)
Interest Rate Swap [Member]
Gain on interest rate swap	$ 227	$ 25