Condensed Consolidated Balance Sheets (Current Period Unaudited) (Parentheticals) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Trade, allowance	$ 3,722	$ 3,191
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, authorized (in shares)	10,000,000	10,000,000
Preferred stock, issued (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, authorized (in shares)	40,000,000	40,000,000
Common stock, issued (in shares)	11,695,719	11,695,719
Common stock, outstanding (in shares)	5,724,939	5,727,895
Treasury stock (in shares)	5,970,780	5,967,824

Amount of allowance for credit loss on accounts receivable, classified as current.

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