Note D - Marketable Securities and Time Deposits (Details Textual) - USD ($) $ in Thousands	6 Months Ended
Jun. 30, 2017	Jun. 30, 2016
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	$ 75,788
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	737
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	183
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	554
Proceeds from Maturities, Prepayments and Calls of Available-for-sale Securities	9,388	$ 21,500
Proceeds from Sale of Available-for-sale Securities	8,578	7,987
Gain (Loss) on Sale of Securities, Net	(58)	$ (33)
Corporate Debt Securities [Member]
Other than Temporary Impairment Losses, Investments, Available-for-sale Securities	$ 0

Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-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 accumulated unrealized loss on investments in debt and equity securities classified as available-for-sale that have been in a continuous loss position for twelve months or longer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 6
-Subparagraph (a)(2)
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This item represents the aggregate fair value of investments in debt and equity securities in an unrealized loss position which are categorized neither as held-to-maturity nor trading securities.

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Amount of accumulated unrealized loss on investments in debt and equity securities classified as available-for-sale that have been in a continuous loss position for less than twelve months.

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The net gain (loss) realized from the sale, exchange, redemption, or retirement of securities, not separately or otherwise categorized as trading, available-for-sale, or held-to-maturity.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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The amount by which the fair value of an investment in debt and equity securities categorized as Available-for-sale is less than the amortized cost basis or carrying amount of that investment at the balance sheet date and the decline in fair value is deemed to be other than temporary, before considering whether or not such amount is recognized in earnings or other comprehensive income.

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The cash inflow associated with maturities (principal being due), prepayments and calls (requests of early payments) on securities not classified as either held-to-maturity securities or trading securities which are classified as available-for-sale securities.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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The cash inflow associated with the sale of debt and equity securities classified as available-for-sale securities.

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