Note 9 - 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		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Outstanding balance at end of period	$ 63,942		$ 63,942		$ 47,979
Weighted average interest rate at end of period	0.06%		0.06%		0.05%
Average outstanding balance during the period	$ 55,673	$ 41,517	$ 51,330	$ 37,465
Average interest rate during the period	0.04%	0.08%	0.04%	0.13%
Maximum outstanding at any month end during the period	$ 63,942	$ 42,722	$ 63,942	$ 42,722