Note 9 - Short-term Borrowings - Overnight Repurchase Agreements (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Repurchase Agreements with Customers [Member]
Average daily balance during the period	$ 4,231	$ 7,831
Average daily interest rate during the period	0.73%	0.38%
Maximum month-end balance during the period	$ 4,177	$ 10,392
Weighted average rate as of end of period	1.00%	0.90%
Federal Funds Purchased [Member]
Average daily balance during the period	$ 12,594	$ 13,059
Average daily interest rate during the period	2.56%	2.18%
Maximum month-end balance during the period	$ 17,010	$ 32,330
Weighted average rate as of end of period	1.50%	2.46%