Note K - Accounting for Stock-based Compensation (Details) - Outstanding Stock Option Activity (Employee Stock Option [Member], USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Employee Stock Option [Member]
Note K - Accounting for Stock-based Compensation (Details) - Outstanding Stock Option Activity [Line Items]
Outstanding, Shares	694,552	638,800	460,653
Outstanding, Weighted Average Exercise Price	$ 24.34	$ 22.21	$ 20.50
Vested plus expected to vest at December 31, 2014	749,645
Vested plus expected to vest at December 31, 2014	$ 28.05
Vested plus expected to vest at December 31, 2014	$ 9,691
Exercisable at December 31, 2014	393,800
Exercisable at December 31, 2014	$ 23.78
Exercisable at December 31, 2014	6,771
Exercised, Shares	(85,063)	(159,309)	(11,521)
Exercisedt, Weighted Average Exercise Price	$ 21.53	$ 19.48	$ 6.73
Granted, Shares	166,861	218,707	203,436
Grantedt, Weighted Average Exercise Price	$ 40.68	$ 27.03	$ 25.39
Forfeited/Expired, Shares	(9,426)	(3,646)	(13,768)
Forfeited/Expiredt, Weighted Average Exercise Price	$ 25.53	$ 24.84	$ 24.58
Outstanding, Shares	766,924	694,552	638,800
Outstanding, Weighted Average Exercise Price	$ 28.20	$ 24.34	$ 22.21
Outstanding, Aggregate Intrinsic Value	$ 9,804

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Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of vested portions of options outstanding and currently exercisable.

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The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

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The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan.

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For presentations that combine terminations, the number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan or that expired.

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Gross number of share options (or share units) granted during the period.

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Amount by which the current fair value of the underlying stock exceeds the exercise price of options outstanding.

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Number of options outstanding, including both vested and non-vested options.

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Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

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Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of fully vested and expected to vest options that are exercisable.

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As of the balance sheet date, the number of shares into which fully vested and expected to vest stock options outstanding can be converted under the option plan.

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As of the balance sheet date, the weighted-average exercise price for outstanding stock options that are fully vested or expected to vest.

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Weighted average price at which option holders acquired shares when converting their stock options into shares.

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Weighted average price at which grantees could have acquired the underlying shares with respect to stock options that were terminated.

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Weighted average per share amount at which grantees can acquire shares of common stock by exercise of options.

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Number of share options (or share units) exercised during the current period.

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