Note D - Marketable Securities and Time Deposits - Marketable Debt Securities by Contractual Maturities (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Marketable debt securities, amortized cost	$ 109,299	$ 108,575
Marketable debt securities, estimated fair value	107,304	$ 107,366
Debt Securities [Member]
Marketable debt securities, amortized cost	109,299
Marketable debt securities, unrealized gains	2
Marketable debt securities, unrealized losses	(1,997)
Marketable debt securities, estimated fair value	107,304
Debt Securities [Member] \| Due in One Year or Less [Member]
Marketable debt securities, amortized cost	30,760
Marketable debt securities, unrealized gains	1
Marketable debt securities, unrealized losses	(77)
Marketable debt securities, estimated fair value	30,684
Debt Securities [Member] \| Due after One Year to Five Years [Member]
Marketable debt securities, amortized cost	78,539
Marketable debt securities, unrealized gains	1
Marketable debt securities, unrealized losses	(1,920)
Marketable debt securities, estimated fair value	$ 76,620

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=82897076&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=82897076&loc=d3e27161-111563

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

+ References

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