Note 8 - Securities Sold Under Agreements to Repurchase - Securities Sold Under Agreements to Repurchase (Details) - Securities Sold under Agreements to Repurchase [Member] - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Outstanding balance at end of period	$ 32,366		$ 31,895
Weighted average interest rate at end of period	0.08%		0.22%
Average outstanding balance during the period	$ 33,413	$ 37,528
Average interest rate during the period	0.19%	0.27%
Maximum outstanding at any month end during the period	$ 33,955	$ 38,445