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Note 1 - Summary of Significant Accounting Policies (Details Textual) - USD ($) shares in Thousands | 3 Months Ended | 12 Months Ended
--- | --- | ---
Dec. 31, 2017 | Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
Number of Days of Delinquent Loans Nonaccrual of Interest |  |  | 90 days |  |
Minimum Number of Days of Discontinued Loan Payments for Modified Loan to be Placed on Nonaccrual |  |  | 90 days |  |
Number of Days Past Due |  |  | 30 days |  |
Threshold for Designation to Impaired Status |  |  | $ 250,000 |  |
Minimum Number of Days Consumer Loans are Past Due for Losses to be Charged Off |  |  | 120 days |  |
Maximum Number of Days Consumer Loans are Past Due for Losses to be Charged Off |  |  | 180 days |  |
Number of Days Loans Secured by Residential Or Commercial Real Estate Are Past Due for Losses to Be Carged Off |  |  | 180 days |  |
Period of Time Between Issuance of Loan Commitment and Closing and Sale of Loans Lower Range |  |  | 30 days |  |
Period of Time Between Issuance of Loan Commitments and Closing and Sale of Loans Upper Range |  |  | 60 days |  |
Noncontrolling Interest, Ownership Percentage by Parent | 100.00% |  | 100.00% |  |
Reclassification of Stranded Tax Effects from Change in Tax Rate |  |  |  |  |
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent |  |  | 35.00% |  |
Income Tax Expense (Benefit), Continuing Operations, Adjustment of Deferred Tax (Asset) Liability | $ 1,560,000 |  | $ 1,560,000 |  |
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount |  |  | 0 | 0 | 0
Advertising Expense |  |  | $ 148,000 | $ 122,000 | $ 105,000
Goodwill, Impairment Loss |  |  | 0 | $ 0 | $ 0
Scenario, Forecast [Member] |  |  |  |  |
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent |  | 21.00% |  |  |
ASU 2018-02 [Member] |  |  |  |  |
Reclassification of Stranded Tax Effects from Change in Tax Rate |  |  | $ 1,718,000 |  |
Minimum [Member] |  |  |  |  |
Finite-Lived Intangible Asset, Useful Life |  |  | 10 years |  |
Maximum [Member] |  |  |  |  |
Finite-Lived Intangible Asset, Useful Life |  |  | 12 years |  |
Building [Member] |  |  |  |  |
Property, Plant and Equipment, Useful Life |  |  | 40 years |  |
Furniture and Fixtures [Member] | Minimum [Member] |  |  |  |  |
Property, Plant and Equipment, Useful Life |  |  | 3 years |  |
Furniture and Fixtures [Member] | Maximum [Member] |  |  |  |  |
Property, Plant and Equipment, Useful Life |  |  | 10 years |  |
Computer Equipment [Member] |  |  |  |  |
Property, Plant and Equipment, Useful Life |  |  | 3 years |  |

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- Definition Minimum period of time between issuance of loans commitment and closing and sale of loans. + References No definition available. + Details
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