Stock-Based Compensation (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended
Mar. 31, 2019	Dec. 31, 2018
Number of Shares
Outstanding - beginning of period	39,000
Granted	0
Exercised	(1,000)
Expired	0
Forfeited	(4,000)
Outstanding - end of period	34,000	39,000
Exercisable - end of period	34,000
Weighted Average Exercise Price
Outstanding - beginning of period	$ 6.26
Granted	0
Exercised	4.22
Expired	0
Forfeited	4.22
Outstanding - end of period	6.56	$ 6.26
Exercisable - end of period	$ 6.56
Weighted Average Remaining Contractual Term
Options outstanding	2 years 2 months 12 days	2 years 9 months 18 days
Options exercisable	2 years 2 months 12 days
Aggregate Intrinsic Value
Outstanding - beginning of period	$ 4,480
Granted	0
Exercised	950
Expired	0
Forfeited	3,360
Outstanding - end of period	9,420	$ 4,480
Options exercisable	$ 9,420

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Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options expired.

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Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options forfeited.

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

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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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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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Number of options or other stock instruments for which the right to exercise has lapsed under the terms of the plan agreements.

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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.

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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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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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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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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 of the plan that expired.

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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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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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Weighted average remaining contractual term for vested portions of options outstanding and currently exercisable or convertible, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Weighted average remaining contractual term for option awards outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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

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