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Percentage of outstanding common stock repurchased period three.

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Percentage of outstanding common stock repurchased period two.

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Treasury stock acquired average cost per share for period five.

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Treasury stock acquired average cost per share for period three.

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Treasury stock acquired average cost per share for period four.

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Treasury stock acquired average cost per share for period two.

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Treasury stock shares repurchased during period Four.

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Treasury stock shares repurchased during period three.

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Treasury stock shares repurchased during period two.

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Total Treasury stock shares repurchased under the December 7, 2011 repurchase program, total.

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Treasury stock value acquired cost method for period four.

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Treasury stock value acquired cost method for period three.

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Treasury stock value acquired cost method for period two.

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Face amount or stated value per share of preferred stock nonredeemable or redeemable solely at the option of the issuer.

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The maximum number of nonredeemable preferred shares (or preferred stock redeemable solely at the option of the issuer) permitted to be issued by an entity's charter and bylaws.

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Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Number of additional shares authorized for issuance under an established share-based compensation plan.

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The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable.

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The grant-date intrinsic value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

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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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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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Period from grant date that an equity-based award expires, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Amount of stock repurchase plan authorized.

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Amount remaining of a stock repurchase plan authorized.

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Number of common and preferred shares that were previously issued and that were repurchased by the issuing entity and held in treasury on the financial statement date. This stock has no voting rights and receives no dividends.

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Shareholders' Equity and Common Stock Equivalents (Details Textual) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage Of Outstanding Common Stock Repurchased Period Two	0.50%
Percentage Of Outstanding Common Stock Repurchased Period Three	1.60%
Percentage Of Outstanding Common Stock Repurchased Period Four	1.70%
Treasury Stock Value Acquired Cost Method For Period Two	$ 5,411
Treasury Stock Value Acquired Cost Method For Period Three	21,950
Treasury Stock Value Acquired Cost Method For Period Four	$ 21,513
Treasury Stock Acquired Average Cost Per Share For Period Two	$ 28.33
Treasury Stock Acquired Average Cost Per Share For Period Three	33.08
Treasury Stock Acquired Average Cost Per share For Period Four	30.65
Treasury Stock Acquired Average Cost Per Share For Period Total	$ 25.18
Stock Repurchase Program, Remaining Authorized Repurchase Amount	$ 29,511
Treasury Stock, Shares	24,672,932	23,971,522		23,308,430	23,117,554
Preferred Stock, Shares Authorized	1,000,000	1,000,000
Preferred Stock, Par or Stated Value Per Share	$ 0.001	$ 0.001
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Grant Date Intrinsic Value	0
Common Stock Closing Market Price Per Share	42.80
Share Based Compensation Arrangement By Share Based Payment Award Options Vested And Exercisable Weighted Average Exercise Price	$ 22.73	$ 19.32		$ 17.20
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Exercisable, Aggregate Intrinsic Value	$ 5,482
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value	$ 11,303
Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period	7 years
Minimum [Member] \| Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	4 years
Minimum [Member] \| Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	1 year
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period	10 years
Maximum [Member] \| Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	5 years
Common Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Treasury Stock Shares For Period Two	190,876
Treasury Stock Shares For Period Three	663,092
Treasury Stock Shares For Period Four	701,410
Treasury Stock Shares Total	2,799,610
2010 Comprehensive Executive Compensation Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant	2,900,000
Share-based Compensation Arrangement by Share-based Payment Award, Number of Additional Shares Authorized	3,250,000
2011 Equity Incentive Plan [Member] \| Common Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock Repurchase Program, Authorized Amount						$ 50,000
2015 Equity Incentive Plan [Member] \| Common Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock Repurchase Program, Authorized Amount			$ 50,000