Note 3 - Debt Securities - Securities by Contractual Maturity (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Securities available for sale, due within one year, amortized cost
Securities available for sale, due after one year but within five years, amortized cost	28,739
Securities available for sale, due after five years but within ten years, amortized cost	50,882
Securities available for sale, due after ten years, amortized cost	11,409
Securities available for sale, single maturity date, amortized cost	91,030
Securities available for sale, amortized cost	168,478	$ 153,477
Securities available for sale, due within one year, fair value
Securities available for sale, due after one year but within five years, fair value	29,049
Securities available for sale, due after five years but within ten years, fair value	51,454
Securities available for sale, due after ten years, fair value	11,409
Securities available for sale, single maturity date, fair value	91,912
Securities available for sale	169,574	153,116
One year or less		25,013
After one year through five years
After five years through ten years
After ten years
Total amortized cost		25,013
One year or less		24,990
After one year through five years
After five years through ten years
After ten years
Total fair value		24,990
US Government Agencies Debt Securities [Member]
Securities available for sale, due within one year, amortized cost
Securities available for sale, due after one year but within five years, amortized cost
Securities available for sale, due after five years but within ten years, amortized cost	1,941
Securities available for sale, due after ten years, amortized cost	3,097
Securities available for sale, single maturity date, amortized cost	5,038
Securities available for sale, amortized cost	5,038	1,108
Securities available for sale, due within one year, fair value
Securities available for sale, due after one year but within five years, fair value
Securities available for sale, due after five years but within ten years, fair value	1,937
Securities available for sale, due after ten years, fair value	3,097
Securities available for sale, single maturity date, fair value	5,034
Securities available for sale	5,034	1,113
One year or less		17,887
After one year through five years
After five years through ten years
After ten years
Total amortized cost		17,887
One year or less		17,867
After one year through five years
After five years through ten years
After ten years
Total fair value		17,867
US Treasury Securities [Member]
Securities available for sale, due within one year, amortized cost
Securities available for sale, due after one year but within five years, amortized cost
Securities available for sale, due after five years but within ten years, amortized cost
Securities available for sale, due after ten years, amortized cost
Securities available for sale, single maturity date, amortized cost
Securities available for sale, amortized cost		19,970
Securities available for sale, due within one year, fair value
Securities available for sale, due after one year but within five years, fair value
Securities available for sale, due after five years but within ten years, fair value
Securities available for sale, due after ten years, fair value
Securities available for sale, single maturity date, fair value
Securities available for sale		19,960
US States and Political Subdivisions Debt Securities [Member]
Securities available for sale, due within one year, amortized cost
Securities available for sale, due after one year but within five years, amortized cost	28,739
Securities available for sale, due after five years but within ten years, amortized cost	48,941
Securities available for sale, due after ten years, amortized cost	8,312
Securities available for sale, single maturity date, amortized cost	85,992
Securities available for sale, amortized cost	85,992	96,886
Securities available for sale, due within one year, fair value
Securities available for sale, due after one year but within five years, fair value	29,049
Securities available for sale, due after five years but within ten years, fair value	49,517
Securities available for sale, due after ten years, fair value	8,312
Securities available for sale, single maturity date, fair value	86,878
Securities available for sale	86,878	97,289
Corporate Debt Securities [Member]
One year or less		7,126
After one year through five years
After five years through ten years
After ten years
Total amortized cost		7,126
One year or less		7,123
After one year through five years
After five years through ten years
After ten years
Total fair value		$ 7,123
Collateralized Mortgage Backed Securities [Member]
Securities available for sale, no single maturity date, amortized cost	77,448
Securities available for sale, no single maturity date, fair value	$ 77,662