Note 7 - Loans Receivable and Credit Disclosures - Amortized Cost Basis of Collateral Dependent Loans (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Jun. 30, 2023	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Dec. 31, 2021
Collateral dependent loans	$ 14,605		$ 14,386
Collateral dependent loans, ACL	16,118	$ 16,319	15,697	$ 15,897	$ 16,420	$ 16,621
Construction Real Estate [Member]
Collateral dependent loans	0		0
Collateral dependent loans, ACL	416	412	730	604	606	675
Family Residential Real Estate 1-4 [Member]
Collateral dependent loans	990		805
Collateral dependent loans, ACL	3,258	3,357	3,028	3,007	2,920	2,752
Multifamily [Member]
Collateral dependent loans	2,948		0
Collateral dependent loans, ACL	2,495	2,524	2,493	2,310	2,517	2,501
Commercial Real Estate Portfolio Segment [Member]
Collateral dependent loans	9,177		12,853
Collateral dependent loans, ACL	4,998	5,033	4,742	5,559	5,843	5,905
Agriculture Real Estate [Member]
Collateral dependent loans	478		165
Collateral dependent loans, ACL	1,229	1,214	1,625	1,598	1,692	1,584
Commercial Portfolio Segment [Member]
Collateral dependent loans	272		200
Collateral dependent loans, ACL	1,874	2,014	1,153	1,099	1,125	1,170
Agriculture [Member]
Collateral dependent loans	726		342
Collateral dependent loans, ACL	1,398	1,358	1,705	1,501	1,484	1,836
Consumer and Other [Member]
Collateral dependent loans	14		21
Collateral dependent loans, ACL	450	$ 407	$ 221	$ 219	$ 233	$ 198
Real Estate [Member]
Collateral dependent loans	13,976
Real Estate [Member] \| Construction Real Estate [Member]
Collateral dependent loans	0
Real Estate [Member] \| Family Residential Real Estate 1-4 [Member]
Collateral dependent loans	990
Real Estate [Member] \| Multifamily [Member]
Collateral dependent loans	2,948
Real Estate [Member] \| Commercial Real Estate Portfolio Segment [Member]
Collateral dependent loans	9,195
Real Estate [Member] \| Agriculture Real Estate [Member]
Collateral dependent loans	478
Real Estate [Member] \| Commercial Portfolio Segment [Member]
Collateral dependent loans	120
Real Estate [Member] \| Agriculture [Member]
Collateral dependent loans	245
Real Estate [Member] \| Consumer and Other [Member]
Collateral dependent loans	0
Equipment [Member]
Collateral dependent loans	39
Equipment [Member] \| Construction Real Estate [Member]
Collateral dependent loans	0
Equipment [Member] \| Family Residential Real Estate 1-4 [Member]
Collateral dependent loans	0
Equipment [Member] \| Multifamily [Member]
Collateral dependent loans	0
Equipment [Member] \| Commercial Real Estate Portfolio Segment [Member]
Collateral dependent loans	0
Equipment [Member] \| Agriculture Real Estate [Member]
Collateral dependent loans	0
Equipment [Member] \| Commercial Portfolio Segment [Member]
Collateral dependent loans	0
Equipment [Member] \| Agriculture [Member]
Collateral dependent loans	39
Equipment [Member] \| Consumer and Other [Member]
Collateral dependent loans	0
Other [Member]
Collateral dependent loans	540
Other [Member] \| Construction Real Estate [Member]
Collateral dependent loans	0
Other [Member] \| Family Residential Real Estate 1-4 [Member]
Collateral dependent loans	0
Other [Member] \| Multifamily [Member]
Collateral dependent loans	0
Other [Member] \| Commercial Real Estate Portfolio Segment [Member]
Collateral dependent loans	0
Other [Member] \| Agriculture Real Estate [Member]
Collateral dependent loans	0
Other [Member] \| Commercial Portfolio Segment [Member]
Collateral dependent loans	98
Other [Member] \| Agriculture [Member]
Collateral dependent loans	442
Collateral Pledged [Member]
Collateral dependent loans	14,555
Collateral dependent loans, ACL	229
Collateral Pledged [Member] \| Construction Real Estate [Member]
Collateral dependent loans	0
Collateral dependent loans, ACL	0
Collateral Pledged [Member] \| Family Residential Real Estate 1-4 [Member]
Collateral dependent loans	990
Collateral dependent loans, ACL	81
Collateral Pledged [Member] \| Multifamily [Member]
Collateral dependent loans	2,948
Collateral dependent loans, ACL	0
Collateral Pledged [Member] \| Commercial Real Estate Portfolio Segment [Member]
Collateral dependent loans	9,195
Collateral dependent loans, ACL	0
Collateral Pledged [Member] \| Agriculture Real Estate [Member]
Collateral dependent loans	478
Collateral dependent loans, ACL	0
Collateral Pledged [Member] \| Commercial Portfolio Segment [Member]
Collateral dependent loans	218
Collateral dependent loans, ACL	95
Collateral Pledged [Member] \| Agriculture [Member]
Collateral dependent loans	726
Collateral dependent loans, ACL	53
Collateral Pledged [Member] \| Consumer and Other [Member]
Collateral dependent loans	0
Collateral dependent loans, ACL	$ 0