Note M - Stockholders' Equity (Details Textual) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Treasury Stock, Shares, Acquired (in shares)	0	282,335
Treasury Stock Acquired, Average Cost Per Share (in dollars per share)		$ 12.19
Treasury Stock, Value, Acquired, Par Value Method		$ 3,443
Stock Repurchase Program, Remaining Number of Shares Authorized to be Repurchased (in shares)	490,209
1993 Employee Stock Purchase Plan (ESPP) [Member]
Stock Issued During Period, Shares, Employee Stock Ownership Plan (in shares)	517,000