Note 3 - Debt and Equity Securities - Sales of Debt and Equity Securities (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Gross proceeds	$ 37,325	$ 39,857	$ 35,555
Gross realized gains	75	102	76
Gross realized losses	(343)	(752)	(251)
Net realized gains (losses)	$ (268)	$ (650)	$ (175)

Amount of realized gain on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
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Amount of realized gain (loss) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
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Amount of realized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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The cash inflow associated with the sale of debt and equity securities classified as available-for-sale securities.

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-Publisher FASB
-Name Accounting Standards Codification
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