Consolidated Balance Sheets (Parentheticals) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Accounts receivable, allowance for doubtful accounts	$ 1,355	$ 1,257
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, authorized (in shares)	50,000,000	50,000,000
Common stock, issued (in shares)	14,315,586	13,968,852
Common stock, outstanding (in shares)	14,315,586	13,968,852