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Stockholders' Equity and Stock Plans - Narrative (Details) $ / shares in Units, $ in Thousands |  | 1 Months Ended | 12 Months Ended |  |  |  |  |
--- | --- | --- | --- | --- | --- | --- | --- | ---
Jan. 20, 2017 $ / shares | Sep. 30, 2015 $ / shares shares | Nov. 30, 2011 investor | Dec. 31, 2016 USD ($) $ / shares shares | Dec. 31, 2015 USD ($) $ / shares shares | Dec. 31, 2014 USD ($) shares | Jun. 17, 2016 | May 11, 2010 shares | Jul. 02, 2007 | Jul. 01, 2007 shares | May 08, 2007 shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |
Number of institutional investors that purchased warrant | investor |  |  | 2 |  |  |  |  |  |  |  |
Unrecognized compensation expense | $ |  |  |  | $ 1,600 |  |  |  |  |  |  |
Total compensation cost for share-based payment arrangements | $ |  |  |  | 994 | $ 636 | $ 446 |  |  |  |  |
Share-based compensation income tax benefit recognized | $ |  |  |  | 318 | 194 | 128 |  |  |  |  |
Tax benefit realized from disqualifying dispositions of incentive stock options | $ |  |  |  | $ 70 | $ 49 | 76 |  |  |  |  |
Percentage of share ownership defining an acquiring person |  |  |  |  |  |  | 10.00% |  | 15.00% |  |
Preferred stock, authorized (in shares) |  |  |  | 5,000,000 | 5,000,000 |  |  |  |  |  |
Preferred stock, no par value (in dollars per share) | $ / shares |  |  |  | $ 0 | $ 0 |  |  |  |  |  |
Subsequent event |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |
Dividends declared per common share (usd per share) | $ / shares | $ 0.27 |  |  |  |  |  |  |  |  |  |
Stock options |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |
Total grant-date fair value of option shares vested | $ |  |  |  | $ 282 | $ 202 | 187 |  |  |  |  |
Stock options | During 2006 through 2014 |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |
Award vesting period |  |  |  | 5 years |  |  |  |  |  |  |
Expiration period of grants |  |  |  | 10 years |  |  |  |  |  |  |
Stock options | During 2006 through 2014 | Vesting Rate, Year One |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |
Vesting percentage |  |  |  | 20.00% |  |  |  |  |  |  |
Stock options | During 2006 through 2014 | Vesting Rate, Year Two |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |
Vesting percentage |  |  |  | 20.00% |  |  |  |  |  |  |
Stock options | During 2006 through 2014 | Vesting Rate, Year Three |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |
Vesting percentage |  |  |  | 20.00% |  |  |  |  |  |  |
Stock options | During 2006 through 2014 | Vesting Rate Year Four |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |
Vesting percentage |  |  |  | 20.00% |  |  |  |  |  |  |
Stock options | During 2006 through 2014 | Vesting Rate Year Five |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |
Vesting percentage |  |  |  | 20.00% |  |  |  |  |  |  |
Stock options | Prior to 2016 |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |
Award vesting period |  |  |  | 4 years |  |  |  |  |  |  |
Expiration period of grants |  |  |  | 7 years |  |  |  |  |  |  |
Stock options | Prior to 2016 | Immediately Upon Grant |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |
Vesting percentage |  |  |  | 20.00% |  |  |  |  |  |  |
Stock options | Prior to 2016 | Vesting Rate, Year One |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |
Vesting percentage |  |  |  | 20.00% |  |  |  |  |  |  |
Stock options | Prior to 2016 | Vesting Rate, Year Two |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |
Vesting percentage |  |  |  | 20.00% |  |  |  |  |  |  |
Stock options | Prior to 2016 | Vesting Rate, Year Three |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |
Vesting percentage |  |  |  | 20.00% |  |  |  |  |  |  |
Stock options | Prior to 2016 | Vesting Rate Year Four |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |
Vesting percentage |  |  |  | 20.00% |  |  |  |  |  |  |
Stock options | After 2014 |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |
Vesting percentage |  |  |  | 33.00% |  |  |  |  |  |  |
Award vesting period |  |  |  | 3 years |  |  |  |  |  |  |
Expiration period of grants |  |  |  | 10 years |  |  |  |  |  |  |
Stock options | During 2016 |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |
Vesting percentage |  |  |  | 33.00% |  |  |  |  |  |  |
Award vesting period |  |  |  | 3 years |  |  |  |  |  |  |
Expiration period of grants |  |  |  | 10 years |  |  |  |  |  |  |
Restricted stock award |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |
Total grant-date fair value of option shares vested | $ |  |  |  | $ 380 | $ 262 | $ 227 |  |  |  |  |
Restricted stock award | During 2006 through 2014 |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |
Award vesting period |  |  |  | 5 years |  |  |  |  |  |  |
Expiration period of grants |  |  |  | 10 years |  |  |  |  |  |  |
Restricted stock award | During 2006 through 2014 | Vesting Rate, Year One |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |
Vesting percentage |  |  |  | 20.00% |  |  |  |  |  |  |
Restricted stock award | During 2006 through 2014 | Vesting Rate, Year Two |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |
Vesting percentage |  |  |  | 20.00% |  |  |  |  |  |  |
Restricted stock award | During 2006 through 2014 | Vesting Rate, Year Three |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |
Vesting percentage |  |  |  | 20.00% |  |  |  |  |  |  |
Restricted stock award | During 2006 through 2014 | Vesting Rate Year Four |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |
Vesting percentage |  |  |  | 20.00% |  |  |  |  |  |  |
Restricted stock award | During 2006 through 2014 | Vesting Rate Year Five |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |
Vesting percentage |  |  |  | 20.00% |  |  |  |  |  |  |
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% |  |  |  |  |  |  |
Director Stock Plan, 2010 |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |
Number of common shares approved to be issued in each plan |  |  |  |  |  |  |  | 150,000 |  |  |
Number of shares available for future grants under plan |  |  |  | 113,842 |  |  |  |  |  |  |
Equity Plan, 2007 |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |
Number of common shares approved to be issued in each plan |  |  |  |  |  |  |  |  |  |  | 500,000
Number of shares available for future grants under plan |  |  |  | 155,750 |  |  |  |  |  |  |
Number of shares to be granted |  |  |  | 250,000 |  |  |  |  |  |  |
Employee Stock Purchase Plan, 2007 |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |
Number of common shares approved to be issued in each plan |  |  |  |  |  |  |  |  |  | 200,000 |
Number of shares available for future grants under plan |  |  |  | 192,965 |  |  |  |  |  |  |
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% |  |  |  |  |  |  |
Former 1999 Stock Option Plan |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |
Number of options granted |  |  |  | 0 |  |  |  |  |  |  |
Common Stock |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |
Number of common stock shares authorized to be purchased by warrant |  | 157,711 |  |  |  |  |  |  |  |  |
Exercise price of warrant to purchase common stock | $ / shares |  | $ 26.63 |  |  |  |  |  |  |  |  |
Net issuance of shares of common stock from cashless exercise (in shares) |  | 70,591 |  |  |  |  |  |  |  |  |
Common Stock | Director Stock Plan, 2010 |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |
Shares awarded in period from plan |  |  |  | 4,607 | 5,295 | 5,306 |  |  |  |  |
Common Stock | U.S. Treasury Capital Purchase Program (TCPP) |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |
Number of common stock shares authorized to be purchased by warrant |  |  |  | 154,242 |  |  |  |  |  |  |
Exercise price of warrant to purchase common stock | $ / shares |  |  |  | $ 27.23 |  |  |  |  |  |  |

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- Definition The maximum number of shares (or other type of equity) originally approved (usually by shareholders and board of directors), net of any subsequent amendments and adjustments, for awards under the equity-based compensation plan. As stock or unit options and equity instruments other than options are awarded to participants, the shares or units remain authorized and become reserved for issuance under outstanding awards (not necessarily vested). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a)(3) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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