Note 6 - Securities Sold Under Agreements to Repurchase - Securities Sold Under Agreement to Repurchase (Details) - USD ($)	9 Months Ended	12 Months Ended
Sep. 30, 2020	Dec. 31, 2019
Securities sold under agreements to repurchase	$ 157,017,000	$ 102,675,000
Average daily balance during the period	129,091,000	105,234,000
Maximum daily balance during the period	$ 173,142,000	$ 133,411,000
Securities Sold under Agreements to Repurchase [Member]
Average interest rate at end of period	0.11%	0.17%
Average interest rate during the period	0.12%	0.24%

The average effective interest rate during the reporting period.

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Amount, after the effects of master netting arrangements, of funds outstanding borrowed in the form of a security repurchase agreement between the entity and another party for the sale and repurchase of identical or substantially the same securities at a date certain for a specified price. Includes liabilities not subject to a master netting arrangement and not elected to be offset.

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Weighted average interest rate of short-term debt outstanding calculated at point in time.

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For the form of debt having an initial term of less than one year or less than the normal operating cycle, if longer, average borrowings during the period.

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For the form of debt having an initial term of less than one year or less than the normal operating cycle, if longer, the maximum amount borrowed at any time during the period.

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