Significant Accounting Policies - Net Income (Loss) Per Share (Details) - shares shares in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Schedule of reconciliation of shares used to calculate basic and diluted earnings per share
Weighted average shares outstanding used to compute basic earnings per share	21,764	21,777	21,787	21,638
Incremental shares issuable upon the assumed exercise of stock options	16	58	19	75
Unvested restricted stock and restricted stock units	232	274	235	366
Shares used to compute diluted earnings per share	22,012	22,109	22,041	22,079
Anti-dilutive shares of restricted stock excluded from the diluted earnings per share calculation	0	0	2	29

Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

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Number of additional shares included in diluted EPS for potentially dilutive effect of nonvested equity-based payment award containing forfeitable rights to dividends or dividend equivalents, whether paid or unpaid.

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Additional shares included in the calculation of diluted EPS as a result of the potentially dilutive effect of share based payment arrangements using the treasury stock method.

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The average number of shares or units issued and outstanding that are used in calculating diluted EPS or earnings per unit (EPU), determined based on the timing of issuance of shares or units in the period.

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Number of [basic] shares or units, after adjustment for contingently issuable shares or units and other shares or units not deemed outstanding, determined by relating the portion of time within a reporting period that common shares or units have been outstanding to the total time in that period.

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