Note 8 - Securities Sold Under Agreements to Repurchase - Securities Sold Under Agreement to Repurchase (Details) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Securities sold under agreements to repurchase	$ 197,463,000	$ 118,365,000
Average daily balance during the year	158,855,000	132,880,000
Maximum daily balance during the year	$ 209,093,000	$ 173,186,000
Securities Sold under Agreements to Repurchase [Member]
Weighted average interest rate at year-end	0.11%	0.12%
Weighted average interest rate during the year	0.11%	0.12%