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Stock Options (Details) - USD ($) |  | 3 Months Ended | 6 Months Ended |
--- | --- | --- | --- | ---
Apr. 18, 2022 | Jun. 30, 2022 | Jun. 30, 2021 | Jun. 30, 2022 | Jun. 30, 2021 | Apr. 05, 2012
Employee Stock Options |  |  |  |  |  |
Stock Options, Aggregate intrinsic value |  |  |  |  |  |
Stock-based compensation expense |  | $ 108,000 | $ 114,000 | $ 229,000 | $ 273,000 |
Employee Stock Options | 2012 Plan |  |  |  |  |  |
Stock option details |  |  |  |  |  |
Shares available for future grants |  |  |  |  |  | 800,000
Maximum exercisable period for granted share-based compensation |  |  |  | 10 years |  |
Number of options granted (in shares) |  |  |  | 31,150 |  |
Stock option activity |  |  |  |  |  |
Options outstanding at the beginning of the period (in shares) |  |  |  | 520,551 |  |
Plus: Options granted (in shares) |  |  |  | 31,150 |  |
Less: |  |  |  |  |  |
Exercise of stock options (in shares) |  |  |  | 17,437 |  |
Options forfeited (in shares) |  |  |  | 7,650 |  |
Options outstanding at the end of the period (in shares) |  | 526,614 |  | 526,614 |  |
Options fully vested and exercisable at the end of the period (in shares) |  | 302,669 |  | 302,669 |  |
Stock Options, Weighted average exercise price |  |  |  |  |  |
Options outstanding at the beginning, weighted average exercise price (in dollars per share) |  |  |  | $ 28.28 |  |
Plus: Options granted, weighted average exercise price (in dollars per share) |  |  |  | 38.92 |  |
Less: |  |  |  |  |  |
Options exercised, weighted average exercise price (in dollars per share) |  |  |  | 22.27 |  |
Options forfeited, weighted average exercise price (in dollars per share) |  |  |  | 32.89 |  |
Options outstanding at the end, weighted average exercise price (in dollars per share) |  | $ 29.04 |  | 29.04 |  |
Options fully vested and exercisable at the end, weighted average exercise price (in dollars per share) |  | $ 24.70 |  | $ 24.70 |  |
Stock Options, Weighted average remaining contractual term (years) |  |  |  |  |  |
Options outstanding at the end, weighted average remaining contractual term (years) |  |  |  | 4 years 4 months 9 days |  |
Options fully vested and exercisable at the end, weighted average remaining contractual term (years) |  |  |  | 2 years 7 months 2 days |  |
Stock Options, Aggregate intrinsic value |  |  |  |  |  |
Options outstanding at the end, aggregate intrinsic value |  | $ 5,812,000 |  | $ 5,812,000 |  |
Options fully vested and exercisable at the end, aggregate intrinsic value |  | 4,656,000 |  | 4,656,000 |  |
Stock-based compensation cost, unrecognized, related to non-vested options |  | $ 982,000 |  | $ 982,000 |  |
Stock-based compensation cost, unrecognized, related to non-vested options, weighted-average period of recognition |  |  |  | 1 year 9 months 18 days |  |
Stock Appreciation Rights | SAR Plan |  |  |  |  |  |
Stock option details |  |  |  |  |  |
Shares available for future grants | 750,000 |  |  |  |  |
Maximum exercisable period for granted share-based compensation | 10 years |  |  |  |  |
Incentive Stock Options to 10 Percent Shareholders [Member] | 2012 Plan |  |  |  |  |  |
Stock option details |  |  |  |  |  |
Maximum exercisable period for granted share-based compensation |  |  |  | 5 years |  |

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