Condensed Consolidated Balance Sheets (Current Period Unaudited) (Parentheticals) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Accumulated depreciation	$ 27,007	$ 26,889
Accumulated amortization, intangible assets	$ 791	$ 757
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	40,000,000	40,000,000
Common stock, shares issued (in shares)	31,227,300	25,639,702
Common stock, shares outstanding (in shares)	30,263,791	25,228,951