Consolidated Balance Sheets (Parentheticals) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Accounts receivable, allowance for doubtful accounts	$ 85	$ 68
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized (in shares)	1,000,000	1,000,000
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, authorized (in shares)	150,000,000	150,000,000
Common stock, issued (in shares)	33,039,146	20,825,452
Common stock, outstanding (in shares)	33,039,146	20,825,452
Series A Preferred Stock [Member]
Preferred stock, shares designated (in shares)	4,250	4,250
Preferred stock, issued (in shares)	0	0
Preferred stock, outstanding (in shares)	0	0