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Note 1 - Summary of Significant Accounting Policies - Effect of Stranded Tax Effect (Details) - USD ($) $ in Thousands |  |  | 12 Months Ended
--- | --- | --- | ---
Jan. 01, 2019 | Dec. 22, 2017 | Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017
Balance |  |  | $ (1,509) | $ 1,487 | $ (1,831)
AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-sale, Parent [Member] |  |  |  |  |
Balance |  | $ 71 |  |  |
Effect of TCJA 14% Federal Tax Rate Reduction on Gross Deferred Tax Amounts | $ 10 |  |  |  |
Accumulated Defined Benefit Plans Adjustment, Net Gain (Loss) Attributable to Parent [Member] |  |  |  |  |
Balance |  | (5,672) |  |  |
Effect of TCJA 14% Federal Tax Rate Reduction on Gross Deferred Tax Amounts | (794) |  |  |  |
AOCI Attributable to Parent [Member] |  |  |  |  |
Balance |  | $ (5,601) | (1,509) | $ 1,487 | $ (1,831)
Effect of TCJA 14% Federal Tax Rate Reduction on Gross Deferred Tax Amounts | $ (784) |  | $ (784) |  |

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