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Note 5 - Common Shares and Earnings Per Share (Details Textual) - USD ($) | 6 Months Ended | 12 Months Ended | 24 Months Ended | 30 Months Ended |  |  |
--- | --- | --- | --- | --- | --- | --- | ---
Dec. 31, 2019 | Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017 | Jun. 30, 2019 | Jun. 30, 2019 | Nov. 08, 2019 | May 03, 2018 | Oct. 13, 2015
Maximum per Share Differences Between Basic and Diluted Earnings per Share in Total or from Continuing or Discontinued Operations |  | $ 0.016 | $ 0.016 | $ 0.016 |  |  |  |  |
The 2014 Stock Incentive Plan [Member] |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized | 1,900,000 | 1,900,000 |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant | 1,010,110 | 1,010,110 |  |  |  |  |  |  |
The 1999 Employee Stock Purchase Plan [Member] |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized | 1,400,000 | 1,400,000 |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant | 349,763 | 349,763 |  |  |  |  |  |  |
Share-based Compensation Arrangements by Share-based Payment Award, Percentage of Market Price at Eligible Employees Granted Options to Purchase Shares | 85.00% | 100.00% |  |  | 100.00% | 15.00% |  |  |
Stock Issued During Period, Shares for Cash Invested under Employee Stock Purchase Plan |  | 13,432 |  | 5,284 |  |  |  |  |
Open Market Share Purchases |  | 3,672 | 7,757 | 4,202 |  |  |  |  |
Dividend Reinvestment and Share Purchase Plan [Member] |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant | 1,220,032 | 1,220,032 |  |  |  |  |  |  |
Stock Issued During Period, Shares for Cash Invested under Employee Stock Purchase Plan |  | 53,339 |  |  |  |  |  |  |
Open Market Share Purchases |  | 109,807 | 116,822 |  |  |  |  |  |
Shelf Registration, Shares |  |  |  |  |  |  |  | 1,500,000 |
Prior Shelf Registration for Dividend Reinvestment and Share Purchase Plan [Member] |  |  |  |  |  |  |  |  |
Stock Issued During Period, Shares for Cash Invested under Employee Stock Purchase Plan |  |  |  | 97,698 |  |  |  |  |
Open Market Share Purchases |  |  | 53,853 | 87,634 |  |  |  |  |
Shelf Registration, Shares |  |  |  |  |  |  |  |  | 1,500,000
Distribution Agreement With KeyBanc [Member] |  |  |  |  |  |  |  |  |
Sale of Stock, Maximum Aggregate Sales Price |  |  |  |  |  |  | $ 75,000,000 |  |
Sale of Stock, Commission Percent |  |  |  |  |  |  | 2.00% |  |

X
- Definition Represents the maximum per share differences between basic and diluted earnings per share in total or from continuing or discontinued operations. + References No definition available. + Details
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- Definition Represents the percentage of the market price of common shares at the end of each six-month purchase period at which eligible employees may purchase shares. + References No definition available. + Details
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- Definition Number of shares authorized for issuance under share-based payment arrangement. + 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 (a)(3) -URI http://asc.fasb.org/extlink&oid=116856206&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://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=116856206&loc=d3e5070-113901 + Details
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