Note E - Marketable Securities and Time Deposits - Marketable Debt Securities by Contractual Maturities (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Marketable debt securities, amortized cost	$ 102,102	$ 112,885
Marketable debt securities, estimated fair value	102,010	$ 111,251
Debt Securities [Member]
Marketable debt securities, amortized cost	102,102
Marketable debt securities, unrealized gains	197
Marketable debt securities, unrealized losses	(289)
Marketable debt securities, estimated fair value	102,010
Debt Securities [Member] \| Due in One Year or Less [Member]
Marketable debt securities, amortized cost	31,073
Marketable debt securities, unrealized gains	53
Marketable debt securities, unrealized losses	(15)
Marketable debt securities, estimated fair value	31,111
Debt Securities [Member] \| Due after One Year to Five Years [Member]
Marketable debt securities, amortized cost	71,029
Marketable debt securities, unrealized gains	144
Marketable debt securities, unrealized losses	(274)
Marketable debt securities, estimated fair value	$ 70,899

Amount, before tax, of unrealized gain 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).

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27161-111563

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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).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27161-111563

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Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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