Note E - Marketable Securities and Time Deposits (Details Textual) - USD ($) $ in Thousands	9 Months Ended
Sep. 30, 2021	Sep. 30, 2020
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	$ 51,324
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	350
Other-than-temporary Impairment Loss, Debt Securities, Portion Recognized in Earnings, Total	0
Proceeds from Maturities, Prepayments and Calls of Debt Securities, Available-for-sale	19,818	$ 46,924
Proceeds from Sale of Debt Securities, Available-for-sale	6,972	24,553
Debt Securities, Available-for-sale, Realized Loss	22	$ 39
Corporate Debt Securities [Member]
Other-than-temporary Impairment Loss, Debt Securities, Portion Recognized in Earnings, Total	$ 0

Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount of realized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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