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		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Hedged interest payments	$ (1,603)	$ (1,575)	$ (3,197)	$ (3,062)
Interest Rate Swap [Member]
Gain on interest rate swap	$ 224	$ 97	$ 451	$ 122