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Stock Options and Restricted Stock - Additional Information (Detail) $ in Thousands | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2018 USD ($) | Sep. 30, 2017 USD ($) | Sep. 30, 2018 USD ($) Incentive_Plan shares | Sep. 30, 2017 USD ($) shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Number of equity incentive plans | Incentive_Plan |  |  | 3 |
Market value of shares granted | $ |  |  | $ 500 | $ 700
Stock options exercised, Shares | shares |  |  | 15,000 | 0
Proceeds from stock option exercises | $ |  |  | $ 67 |
Share-based compensation expense | $ | $ 300 | $ 300 | $ 1,100 | $ 1,300
Executive Officers [Member] |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Common stock granted, shares | shares |  |  | 3,304 | 7,434
Restricted Stock Units (RSUs) [Member] | Non-employee Directors [Member] |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Common stock granted, shares | shares |  |  | 5,761 | 6,454

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