Note 7 - Securities Available for Sale - Summary of Securities Available for Sale (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Securities available for sale, amortized cost	$ 116,700	$ 107,528
Investment securities available for sale, gross unrealized gains	2,005	185
Investment securities available for sale, gross unrealized losses	(141)	(121)
Securities available for sale	118,564	107,592
Collateralized Mortgage Backed Securities [Member]
Securities available for sale, amortized cost	69,826	54,777
Investment securities available for sale, gross unrealized gains	1,667	139
Investment securities available for sale, gross unrealized losses	(35)	(65)
Securities available for sale	71,458	54,851
Other Marketable Securities [Member]
Securities available for sale, amortized cost	46,874	52,751
Investment securities available for sale, gross unrealized gains	338	46
Investment securities available for sale, gross unrealized losses	(106)	(56)
Securities available for sale	47,106	52,741
Federal National Mortgage Association Certificates and Obligations (FNMA) [Member] | Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Securities available for sale, amortized cost	52,922	46,604
Investment securities available for sale, gross unrealized gains	1,388	47
Investment securities available for sale, gross unrealized losses	(35)	(65)
Securities available for sale	54,275	46,586
Federal National Mortgage Association Certificates and Obligations (FNMA) [Member] | Collateralized Mortgage Obligations [Member]
Securities available for sale, amortized cost	121	169
Investment securities available for sale, gross unrealized gains	7	4
Investment securities available for sale, gross unrealized losses	0	0
Securities available for sale	128	173
Federal Home Loan Mortgage Corporation Certificates and Obligations (FHLMC) [Member] | Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Securities available for sale, amortized cost	16,783	8,004
Investment securities available for sale, gross unrealized gains	272	88
Investment securities available for sale, gross unrealized losses	0	0
Securities available for sale	17,055	8,092
US Government Agencies Debt Securities [Member] | Other Marketable Securities [Member]
Securities available for sale, amortized cost	45,046	49,974
Investment securities available for sale, gross unrealized gains	333	39
Investment securities available for sale, gross unrealized losses	0	(21)
Securities available for sale	45,379	49,992
US States and Political Subdivisions Debt Securities [Member] | Other Marketable Securities [Member]
Securities available for sale, amortized cost	1,091	1,969
Investment securities available for sale, gross unrealized gains	5	7
Investment securities available for sale, gross unrealized losses	0	0
Securities available for sale	1,096	1,976
Corporate Debt Securities [Member] | Other Marketable Securities [Member]
Securities available for sale, amortized cost	37	108
Investment securities available for sale, gross unrealized gains	0	0
Investment securities available for sale, gross unrealized losses	(1)	0
Securities available for sale	36	108
Preferred Stock [Member] | Other Marketable Securities [Member]
Securities available for sale, amortized cost	700	700
Investment securities available for sale, gross unrealized gains	0	0
Investment securities available for sale, gross unrealized losses	(105)	(35)
Securities available for sale	$ 595	$ 665