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Stockholders' Equity and Stock Plans - Narrative (Details) $ / shares in Units, $ in Thousands |  |  |  | 3 Months Ended | 12 Months Ended |  |  |  |
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Jan. 22, 2021 $ / shares | Nov. 27, 2018 | Jul. 01, 2017 | Mar. 31, 2018 USD ($) | Dec. 31, 2020 USD ($) $ / shares shares | Dec. 31, 2019 USD ($) $ / shares shares | Dec. 31, 2018 USD ($) shares | May 12, 2020 shares | Jan. 24, 2020 USD ($) | Apr. 23, 2018 USD ($) | Jul. 06, 2017 $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |
Stock split ratio |  | 2 |  |  |  |  |  |  |  |  |
Total compensation cost for share-based payment arrangements | $ |  |  |  |  | $ 1,200 | $ 1,500 | $ 1,700 |  |  |  |
Share-based compensation income tax benefit recognized | $ |  |  |  |  | 341 | 389 | 404 |  |  |  |
Unrecognized compensation expense | $ |  |  |  |  | $ 652 |  |  |  |  |  |
Period for recognizing unrecognized compensation expense |  |  |  |  | 1 year 8 months 12 days |  |  |  |  |  |
Excess tax benefits recorded as a reduction to income tax expense | $ |  |  |  |  | $ 120 | $ 145 | 484 |  |  |  |
Percentage of share ownership defining an acquiring person |  |  |  |  |  |  |  |  |  |  | 10.00%
Preferred stock, authorized (in shares) |  |  |  |  | 5,000,000 | 5,000,000 |  |  |  |  |
Preferred stock, no par value (in dollars per share) | $ / shares |  |  |  |  | $ 0 | $ 0 |  |  |  |  |
Stock repurchase program, authorized amount | $ |  |  |  |  |  |  |  |  | $ 25,000 | $ 25,000 |
Subsequent event |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |
Dividends declared per common share (usd per share) | $ / shares | $ 0.23 |  |  |  |  |  |  |  |  |  |
Restricted stock award |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |
Total grant-date fair value of option shares vested | $ |  |  |  |  | $ 1,200 | $ 1,200 | 967 |  |  |  |
Stock options |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |
Expiration period of grants |  |  |  |  | 10 years |  |  |  |  |  |
Total grant-date fair value of option shares vested | $ |  |  |  |  | $ 484 | $ 473 | $ 543 |  |  |  |
Stock options | During 2016 |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |
Award vesting period |  |  |  |  | 3 years |  |  |  |  |  |
Expiration period of grants |  |  |  |  | 10 years |  |  |  |  |  |
Stock options | Subsequent To January 1, 2015 |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |
Vesting percentage |  |  |  |  | 33.33% |  |  |  |  |  |
Performance shares |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |
Award vesting period |  |  |  |  | 3 years |  |  |  |  |  |
Minimum | Performance shares |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |
Vesting percentage |  |  |  |  | 0.00% |  |  |  |  |  |
Maximum | Performance shares |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |
Vesting percentage |  |  |  |  | 200.00% |  |  |  |  |  |
The Plan, 2020 |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |
Shares approved to be issued in common stock (in shares) |  |  |  |  |  |  |  | 250,000 |  |  |
Number of shares available for future grants under plan (in shares) |  |  |  |  | 246,141 |  |  |  |  |  |
Director Stock Plan, 2010 |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |
Shares approved to be issued in common stock (in shares) |  |  |  |  |  |  |  | 205,253 |  |  |
Employee Stock Purchase Plan, 2007 |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |
Number of shares available for future grants under plan (in shares) |  |  |  |  | 380,123 |  |  |  |  |  |
Discount from closing market price at end of each quarter |  |  | 5.00% |  |  |  |  |  |  |  |
Employee Stock Purchase Plan, 2007 | Minimum |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |
Approved payroll deduction to purchase shares, percentage |  |  | 1.00% |  |  |  |  |  |  |  |
Employee Stock Purchase Plan, 2007 | Maximum |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |
Approved payroll deduction to purchase shares, percentage |  |  | 15.00% |  |  |  |  |  |  |  |
The 2017 Equity Plan |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |
Number of shares available for future grants under plan (in shares) |  |  |  |  | 940,918 |  |  |  |  |  |
Common Stock | The Plan, 2020 |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |
Shares awarded in period from plan (in shares) |  |  |  |  | 5,723 |  |  |  |  |  |
Common Stock | Director Stock Plan, 2010 |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |
Shares awarded in period from plan (in shares) |  |  |  |  |  | 5,544 | 5,470 |  |  |  |
Series A Junior Participating Preferred Stock |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |
Preferred stock, authorized (in shares) |  |  |  |  | 1,000,000 |  |  |  |  |  |
Preferred stock, no par value (in dollars per share) | $ / shares |  |  |  |  | $ 0 |  |  |  |  |  |
Retained Earnings |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |
Amount reclassified from AOCI to retained earnings representing stranded tax income effects | $ |  |  |  | $ 638 |  |  | $ 638 |  |  |  |
Series A Junior Participating Preferred Stock |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |
Exercise price of rights (in dollars per share) | $ / shares |  |  |  |  |  |  |  |  |  |  | $ 0.9
Number of securities called by each right (in shares) |  |  |  |  |  |  |  |  |  |  | 0.005

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