Condensed Consolidated Balance Sheets (Current Period Unaudited) (Parentheticals) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Accounts receivable, allowance for doubtful accounts	$ 1,324	$ 3,393
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	50,000,000	50,000,000
Common stock, shares issued (in shares)	18,020,973	16,382,543
Common stock, shares outstanding (in shares)	18,020,973	16,382,543