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Stock Options and Stock Appreciation Rights - Options (Details) - USD ($) | 12 Months Ended |
--- | --- | ---
Dec. 31, 2024 | Dec. 31, 2023 | Dec. 31, 2022 | Apr. 05, 2012
Employee Stock Option |  |  |  |
Stock option details |  |  |  |
Shares available for future grants |  |  |  | 800,000
Maximum exercisable period for granted share-based compensation | 10 years |  |  |
Stock option activity |  |  |  |
Options outstanding at the beginning of the period (in shares) | 383,865 |  |  |
Less: |  |  |  |
Options exercised (in shares) | (149,773) |  |  |
Options forfeited (in shares) | (21,937) |  |  |
Options outstanding at the end of the period (in shares) | 212,155 | 383,865 |  |
Options fully vested and exercisable at the end of the period (in shares) | 121,714 |  |  |
Stock Options, Weighted average exercise price |  |  |  |
Options outstanding at the beginning, weighted average exercise price (in dollars per share) | $ 30.65 |  |  |
Less: |  |  |  |
Options exercised, weighted average exercise price (in dollars per share) | 25.08 |  |  |
Options forfeited, weighted average exercise price (in dollars per share) | 23.93 |  |  |
Options outstanding at the end, weighted average exercise price (in dollars per share) | 35.27 | $ 30.65 |  |
Options fully vested and exercisable at the end, weighted average exercise price (in dollars per share) | $ 35.92 |  |  |
Stock Options, Weighted average remaining contractual term (years) |  |  |  |
Options outstanding at the end, weighted average remaining contractual term (years) | 4 years 1 month 17 days |  |  |
Options fully vested and exercisable at the end, weighted average remaining contractual term (years) | 3 years 3 months 21 days |  |  |
Stock Options, Aggregate intrinsic value |  |  |  |
Options outstanding at the end, aggregate intrinsic value | $ 5,918,000 |  |  |
Options fully vested and exercisable at the end, aggregate intrinsic value | 3,316,000 |  |  |
Stock-based compensation expense | 214,000 | $ 330,000 | $ 449,000 |
Stock-based compensation cost, unrecognized | $ 218,000 |  |  |
Stock-based compensation cost, unrecognized, weighted-average period of recognition | 1 year 4 months 24 days |  |  |
Other information pertaining to option activity |  |  |  |
Weighted average grant date fair value of stock options granted (in dollars per share) |  |  | $ 11.24 |
Total fair value of stock options vested | $ 616,286 | 514,000 | $ 514,000 |
Total intrinsic value of stock options exercised | $ 4,640,000 | $ 1,060,000 | $ 1,670,000 |
Incentive Stock Options to 10 Percent Shareholders |  |  |  |
Stock option details |  |  |  |
Maximum exercisable period for granted share-based compensation | 5 years |  |  |

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