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Stock Options (Details) - USD ($) $ / shares in Units, $ in Thousands | 3 Months Ended | 9 Months Ended |
--- | --- | --- | ---
Sep. 30, 2019 | Sep. 30, 2018 | Sep. 30, 2019 | Sep. 30, 2018 | Apr. 05, 2012
Stock options under 2012 Plan |  |  |  |  |
Stock option details |  |  |  |  |
Shares available for future grants | 27,276 |  | 27,276 |  | 800,000
Maximum exercisable period for options granted |  |  | 10 years |  |
Stock option activity |  |  |  |  |
Options outstanding at the beginning of the period (in shares) |  |  | 788,977 |  |
Plus: Options granted (in shares) |  |  | 16,500 |  |
Less: |  |  |  |  |
Options exercised (in shares) |  |  | 87,663 |  |
Options forfeited (in shares) |  |  | 34,576 |  |
Options outstanding at the end of the period (in shares) | 683,238 |  | 683,238 |  |
Options fully vested and exercisable at the end of the period (in shares) | 322,772 |  | 322,772 |  |
Stock Options, Weighted average exercise price |  |  |  |  |
Options outstanding at the beginning, weighted average exercise price (in dollars per share) |  |  | $ 25.91 |  |
Plus: Options granted, weighted average exercise price (in dollars per share) |  |  | 35.34 |  |
Less: |  |  |  |  |
Options exercised, weighted average exercise price (in dollars per share) |  |  | 17.30 |  |
Options forfeited, weighted average exercise price (in dollars per share) |  |  | 26.95 |  |
Options outstanding at the end, weighted average exercise price (in dollars per share) | $ 27.19 |  | 27.19 |  |
Options fully vested and exercisable at the end, weighted average exercise price (in dollars per share) | $ 22.08 |  | $ 22.08 |  |
Stock Options, Weighted average remaining contractual term (years) |  |  |  |  |
Options outstanding at the end, weighted average remaining contractual term (years) |  |  | 5 years 10 months 9 days |  |
Options fully vested and exercisable at the end, weighted average remaining contractual term (years) |  |  | 4 years 7 months 13 days |  |
Stock Options, Aggregate intrinsic value |  |  |  |  |
Options outstanding at the end, aggregate intrinsic value | $ 7,809 |  | $ 7,809 |  |
Options fully vested and exercisable at the end, aggregate intrinsic value | 5,339 |  | 5,339 |  |
Stock-based compensation expense | 240 | $ 285 | 744 | $ 755 |
Stock-based compensation cost, unrecognized, related to non-vested options | $ 2,158 |  | $ 2,158 |  |
Stock-based compensation cost, unrecognized, related to non-vested options, weighted-average period of recognition |  |  | 1 year 10 months 24 days |  |
Incentive stock options granted to 10% shareholders |  |  |  |  |
Stock option details |  |  |  |  |
Maximum exercisable period for options granted |  |  | 5 years |  |

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