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Stock Options (Details) - USD ($) | 3 Months Ended | 6 Months Ended |
--- | --- | --- | ---
Jun. 30, 2016 | Jun. 30, 2015 | Jun. 30, 2016 | Jun. 30, 2015 | Apr. 05, 2012
Stock options under 2012 Plan |  |  |  |  |
Stock option details |  |  |  |  |
Shares available for future grants | 190,250 |  | 190,250 |  | 800,000
Maximum exercisable period for options granted |  |  | 10 years |  |
Stock option activity |  |  |  |  |
Options outstanding at the beginning of the period (in shares) |  |  | 871,727 |  |
Plus: Options granted (in shares) |  |  | 4,000 |  |
Less: |  |  |  |  |
Options exercised (in shares) |  |  | 14,900 |  |
Options forfeited (in shares) |  |  | 18,000 |  |
Options outstanding at the end of the period (in shares) | 842,827 |  | 842,827 |  |
Options fully vested and exercisable at the end of the period (in shares) | 246,708 |  | 246,708 |  |
Stock Options, Weighted Average Exercise Price |  |  |  |  |
Options outstanding at the beginning, weighted average exercise price (in dollars per share) |  |  | $ 19.08 |  |
Plus: Options granted, weighted average exercise price (in dollars per share) |  |  | 22.07 |  |
Less: |  |  |  |  |
Options exercised, weighted average exercise price (in dollars per share) |  |  | 11.29 |  |
Options forfeited, weighted average exercise price (in dollars per share) |  |  | 21.07 |  |
Options outstanding at the end, weighted average exercise price (in dollars per share) | $ 19.19 |  | 19.19 |  |
Options fully vested and exercisable at the end, weighted average exercise price (in dollars per share) | $ 15.63 |  | $ 15.63 |  |
Stock Options, Weighted Average Remaining Contractual Term |  |  |  |  |
Options outstanding at the end, weighted average remaining contractual term |  |  | 6 years 2 months 27 days |  |
Options fully vested and exercisable at the end, weighted average remaining contractual term |  |  | 3 years 11 months 1 day |  |
Stock Options, Aggregate Intrinsic Value |  |  |  |  |
Options outstanding at the end, aggregate intrinsic value | $ 5,814,000 |  | $ 5,814,000 |  |
Options fully vested and exercisable at the end, aggregate intrinsic value | 2,581,000 |  | 2,581,000 |  |
Stock-based compensation expense | 269,000 | $ 291,000 | 554,000 | $ 583,000 |
Stock-based compensation cost, unrecognized, related to non-vested options | $ 2,809,000 |  | $ 2,809,000 |  |
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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