Consolidated Balance Sheets (Parentheticals) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Trade, allowance	$ 3,482	$ 2,952	$ 2,224	$ 1,335
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	11,656,160
Common stock, outstanding (in shares)	5,727,895	5,748,897
Treasury stock (in shares)	5,967,824	5,907,263

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

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