Note 8 - Borrowed Funds - Comparative Data for Securities Sold Under Agreements to Repurchase (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Average amount outstanding during the year (1)	[1]	$ 0	$ 49,589	$ 136,849
Maximum amount outstanding at month-end (2)	[2]	0	100,000	150,000
Balance, December 31		$ 0	$ 0	$ 100,000
Rate, December 31		0.00%	0.00%	2.86%
Securities Sold under Agreements to Repurchase 1 [Member]
Weighted average interest rate for the year		0.00%	0.00%	3.11%

[1] Average balances were computed using daily averages.

[2] Highest month-end balances were January 2018 and January 2017.