Note 8 - Borrowed Funds - Comparative Data for Securities Sold Under Agreements to Repurchase (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Average amount outstanding during the year	[1]	$ 0	$ 0	$ 49,589
Maximum amount outstanding at month-end	[2]	0	0	100,000
Balance		$ 0	$ 0	$ 0
Rate		0.00%	0.00%	0.00%
Securities Sold under Agreements to Repurchase 1 [Member]
Weighted average interest rate for the year		0.00%	0.00%	0.00%

[1] Average balances were computed using daily averages.

[2] Highest month-end balance was January 2018.