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Note 13 - Share-based Compensation (Details Textual) $ / shares in Units, $ in Thousands | 12 Months Ended
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Dec. 31, 2020 USD ($) $ / shares shares | Dec. 31, 2019 USD ($) $ / shares shares | Dec. 31, 2018 USD ($) $ / shares shares
Number Of Active Stock Incentive Plans |  | 1 |  |
Common Stock, Capital Shares Reserved for Future Issuance (in shares) |  | 354,022 |  |
Common Stock, Capital Shares Reserved for Future Issuance, Percentage Vesting of Outstanding PSAs Assumed |  | 100.00% |  |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Net of Forfeitures, Total (in shares) |  | 0 | 0 | 0
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period (in shares) |  | 24,000 | 0 | 0
Share-based Compensation Arrangements by Share-based Payment Award, Options, Exercises in Period, Weighted Average Exercise Price (in dollars per share) | $ / shares |  | $ 24.15 |  |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value | $ |  | $ 100 |  |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number, Ending Balance (in shares) |  | 0 |  |
Restricted Stock Units and Performance Share Award Target Level, Percentage |  |  | 100.00% |
Director [Member] |  |  |  |
Share-based Goods and Nonemployee Services Transaction, Quantity of Securities Issued (in shares) |  | 17,442 | 11,924 | 11,172
Share-based Compensation Arrangement by Stock-based Payment Award, Grant Date Fair Value (in dollars per share) | $ / shares |  | $ 25.81 | $ 25.16 | $ 21.48
Share-based Payment Arrangement, Option [Member] |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period (Month) |  | 60 months |  |
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period (Year) |  | 10 years |  |
Restricted Stock Units (RSUs) [Member] |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period (Month) |  | 3 years |  |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value (in dollars per share) | $ / shares |  | $ 26.61 | 23.56 |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares) |  |  |  | 0
Performance Shares [Member] |  |  |  |
Restricted Stock Units and Performance Share Award Target Level, Percentage |  | 100.00% |  |
Performance Awards Issued Multiplier |  | 136.00% |  |
Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Number At Target Level Of Performance (in shares) |  | 91,000 |  |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value (in dollars per share) | $ / shares |  | $ 26.61 | $ 23.56 | $ 19.97
Performance Shares [Member] | Minimum [Member] |  |  |  |
Performance Awards Issued Multiplier |  | 0.00% |  |
Performance Shares [Member] | Maximum [Member] |  |  |  |
Performance Awards Issued Multiplier |  | 200.00% |  |
Restricted Stock Units and Performance Stock Awards [Member] |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value (in dollars per share) | $ / shares |  | $ 26.61 |  |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares) | [1] | 97,834 |  |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Fair Value | $ |  | $ 2,000 | $ 0 | $ 1,600
Share-based Payment Arrangement, Nonvested Award, Excluding Option, Cost Not yet Recognized, Amount | $ |  | $ 2,500 |  |
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition (Year) |  | 1 year 7 months 6 days |  |
[1] | The number of PSAs disclosed in this table are at the target level of 100%.

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- Definition The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2)(iii)(1) -URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901 + Details
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