Consolidated Balance Sheets (Parentheticals) - USD ($) $ / shares in Thousands, $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Accounts receivable, allowance for doubtful accounts	$ 50	$ 50
Preferred stock, par value (in dollars per share)	$ 0	$ 0
Preferred stock, shares authorized (in shares)	10,000,000	10,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0	$ 0
Common stock, shares authorized (in shares)	37,500,000	37,500,000
Common stock, shares issued (in shares)	20,374,406	13,235,038
Common stock, shares outstanding (in shares)	20,374,406	13,235,038