Condensed Consolidated Balance Sheets (Current Period Unaudited) (Parentheticals) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019	[1]
Accounts receivable, allowance for doubtful accounts	$ 481	$ 407
Convertible preferred stock, shares authorized (in shares)	10,000,000	10,000,000
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized (in shares)	75,000,000	75,000,000
Common stock, shares issued (in shares)	10,028,203	7,075,684
Common stock, shares outstanding (in shares)	10,028,203	7,075,684
Series A Preferred Stock [Member]
Convertible preferred stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Convertible preferred stock, shares issued (in shares)	0	1,852,173
Convertible preferred stock, shares outstanding (in shares)	0	1,852,173
Series B Preferred Stock [Member]
Convertible preferred stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Convertible preferred stock, shares issued (in shares)	32,667	31,678
Convertible preferred stock, shares outstanding (in shares)	32,667	31,678

[1] The condensed consolidated balance sheet as of December 31, 2019 has been derived from the audited consolidated financial statements as of that date.