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Note 8 - Employee Benefit Plans (Details Textual) - USD ($) $ in Thousands | 12 Months Ended
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Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
Defined Contribution Plan, Maximum Annual Contributions Per Employee, Percent | 100.00% |  |
Defined Contribution Plan, Employer Discretionary Contribution Amount | $ 340 | $ 315 | $ 294
Age Attained to be Eligible for ESOP | 21 years |  |
Employee Stock Ownership Plan (ESOP), Cash Contributions to ESOP | $ 200 | 150 | 200
Employee Stock Ownership Plan (ESOP), Number of Allocated Shares | 236,221 |  |
Age of Employees Required to Diversify Allocated ESOP Shares | 55 years |  |
Years of Plan Participation Required to Diversify Allocated ESOP Shares | 10 years |  |
Percentage of Allocated ESOP Shares That Can be Diversified | 50.00% |  |
Accrued Expenses for Salary Continuation Plan | $ 272 | $ 242 | $ 396
Equity Securities [Member] |  |  |
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage | 65.00% |  |
Fixed Income Securities [Member] |  |  |
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage | 35.00% |  |
Hedge Funds [Member] |  |  |
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage | 0.00% |  |
Private Equity Funds [Member] |  |  |
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage | 0.00% |  |
Real Estate [Member] |  |  |
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage | 0.00% |  |

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- Definition Liability for agreement to continue an employee's salary after termination of employment including retirement, death, disability, or other event. For example, a company may agree to continue a disabled employee's salary for six months. + References No definition available. + Details
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- Definition Age of an employee to be eligible for the Employee Stock Ownership Plan (ESOP). + References No definition available. + Details
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- Definition Age required to diversify allocated Employee Stock Ownership Plan (ESOP) shares. + References No definition available. + Details
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- Definition Percentage of allocated Employee Stock Ownership Plan shares that can diversified. + References No definition available. + Details
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- Definition Years of plan participation required to diversify Employee Stock Ownership Plan (ESOP). + References No definition available. + Details
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- Definition Percentage of target investment allocation to total plan assets. Includes, but is not limited to, percentage on weighted-average basis if more than one plan. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (d)(5)(i) -URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920 + Details
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- Definition Amount of discretionary contributions made by an employer to a defined contribution plan. + References No definition available. + Details
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- Definition Maximum percentage of employee gross pay the employee may contribute to a defined contribution plan. + References No definition available. + Details
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- Definition This item represents the amount of cash contributions during the period made by the entity to the Employee Stock Ownership Plan (ESOP). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 40 -Section 50 -Paragraph 1 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=65895303&loc=d3e17540-113929 + Details
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- Definition The shares or units in an ESOP trust that have been assigned to individual participant accounts based on a known formula. IRS rules require allocations to be nondiscriminatory generally based on compensation, length of service, or a combination of both. For any particular participant such shares or units may be vested, unvested, or partially vested. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 40 -Section 50 -Paragraph 1 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=65895303&loc=d3e17540-113929 + Details
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