Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

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Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Unrecognized cost of unvested options awarded to employees as compensation.

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Amount of cash inflow from exercise of stock options granted under share-based compensation arrangement.

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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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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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

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The maximum number of shares (or other type of equity) originally approved (usually by shareholders and board of directors), net of any subsequent amendments and adjustments, for awards under the equity-based compensation plan. As stock or unit options and equity instruments other than options are awarded to participants, the shares or units remain authorized and become reserved for issuance under outstanding awards (not necessarily vested).

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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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Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares.

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

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

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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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Stock-Based Compensation (Stock Options Narrative) (Details) - USD ($) $ / shares in Units, $ in Thousands			12 Months Ended
	Jun. 16, 2016	Jun. 16, 2009	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 1998
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)			0	32,750	0
Weighted average grant date fair value of options granted (in dollars per share)			$ 0	$ 11.93
Total intrinsic value of options exercised			$ 216	$ 446	$ 625
Proceeds from exercise of stock options			680	1,120	1,042
Unrecognized compensation cost related to stock options			131
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense			$ 159	$ 363	$ 506
Unrecognized compensation cost related to stock options, weighted average period for recognition			1 year
Stock Options \| 1998 Stock Option Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period			3 years
Award expiration period			10 years
Stock Options \| 1998 Stock Option Plan \| Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized (in shares)	1,000,000.0					550,000
Additional shares authorized (in shares)	250,000	200,000
Number of shares available for grant (in shares)			318,503