Note 9 - Allowance for Credit Losses and Credit Quality Information - Credit Quality Indicators (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
loans, current year	$ 24,622	$ 173,139
loans, one year before	174,578	271,054
loans, two years before	263,954	180,364
loans, three years before	176,548	125,999
loans, four years before	122,038	28,889
loans, prior	59,026	32,502
loans, revolving	47,964	46,161
Loans receivable	868,730	858,108
Current period gross charge-offs, year one		174
Current period gross charge-offs, year two		0
Current period gross charge-offs, year three		0
Current period gross charge-offs, year four		0
Current period gross charge-offs, year five		0
Current period gross charge-offs, prior		0
Current period gross charge-offs, revolving		160
Current period gross charge-offs, total	30	334
Residential Portfolio Segment [Member]
loans, current year	2,823	81,134
loans, one year before	80,466	60,531
loans, two years before	57,331	62,690
loans, three years before	61,380	33,716
loans, four years before	33,035	11,121
loans, prior	25,567	15,111
loans, revolving	0	0
Loans receivable	260,602	264,303
Current period gross charge-offs, year one	0
Current period gross charge-offs, year two	0
Current period gross charge-offs, year three	0
Current period gross charge-offs, year four	0
Current period gross charge-offs, year five	0
Current period gross charge-offs, prior	30
Current period gross charge-offs, revolving	0
Current period gross charge-offs, total	30
Residential Portfolio Segment [Member] | Pass [Member]
loans, current year	2,823
loans, one year before	80,466
loans, two years before	56,798
loans, three years before	61,380
loans, four years before	32,958
loans, prior	24,686
loans, revolving	0
Loans receivable	259,111
Residential Portfolio Segment [Member] | Unclassified [Member]
loans, current year		81,070
loans, one year before		59,474
loans, two years before		62,690
loans, three years before		33,637
loans, four years before		10,915
loans, prior		14,635
loans, revolving		0
Loans receivable		262,421
Residential Portfolio Segment [Member] | Special Mention [Member]
loans, current year	0	0
loans, one year before	0	511
loans, two years before	0	0
loans, three years before	0	0
loans, four years before	0	0
loans, prior	0	0
loans, revolving	0	0
Loans receivable	0	511
Residential Portfolio Segment [Member] | Substandard [Member]
loans, current year	0	64
loans, one year before	0	546
loans, two years before	533	0
loans, three years before	0	79
loans, four years before	77	182
loans, prior	846	462
loans, revolving	0	0
Loans receivable	1,456	1,333
Residential Portfolio Segment [Member] | Doubtful [Member]
loans, current year	0	0
loans, one year before	0	0
loans, two years before	0	0
loans, three years before	0	0
loans, four years before	0	24
loans, prior	35	14
loans, revolving	0	0
Loans receivable	35	38
Residential Portfolio Segment [Member] | Loss [Member]
loans, current year	0	0
loans, one year before	0	0
loans, two years before	0	0
loans, three years before	0	0
loans, four years before	0	0
loans, prior	0	0
loans, revolving	0	0
Loans receivable	0	0
Commercial Real Estate Portfolio Segment [Member]
loans, current year	16,281	67,939
loans, one year before	73,267	195,464
loans, two years before	193,079	112,209
loans, three years before	110,315	86,992
loans, four years before	84,149	15,168
loans, prior	26,248	12,181
loans, revolving	0	0
Loans receivable	503,339	489,953
Current period gross charge-offs, total	(0)
Commercial Real Estate Portfolio Segment [Member] | Pass [Member]
loans, current year	16,281
loans, one year before	70,863
loans, two years before	184,499
loans, three years before	107,230
loans, four years before	71,955
loans, prior	23,054
loans, revolving	0
Loans receivable	473,882
Commercial Real Estate Portfolio Segment [Member] | Unclassified [Member]
loans, current year		64,688
loans, one year before		187,320
loans, two years before		109,729
loans, three years before		75,754
loans, four years before		14,531
loans, prior		9,603
loans, revolving		0
Loans receivable		461,625
Commercial Real Estate Portfolio Segment [Member] | Special Mention [Member]
loans, current year	0	1,026
loans, one year before	1,942	7,756
loans, two years before	8,233	2,188
loans, three years before	2,175	371
loans, four years before	1,246	0
loans, prior	1,006	1,016
loans, revolving	0	0
Loans receivable	14,602	12,357
Commercial Real Estate Portfolio Segment [Member] | Substandard [Member]
loans, current year	0	2,225
loans, one year before	462	388
loans, two years before	347	292
loans, three years before	910	10,867
loans, four years before	10,948	637
loans, prior	2,188	1,562
loans, revolving	0	0
Loans receivable	14,855	15,971
Commercial Real Estate Portfolio Segment [Member] | Doubtful [Member]
loans, current year	0	0
loans, one year before	0	0
loans, two years before	0	0
loans, three years before	0	0
loans, four years before	0	0
loans, prior	0	0
loans, revolving	0	0
Loans receivable	0	0
Commercial Real Estate Portfolio Segment [Member] | Loss [Member]
loans, current year	0	0
loans, one year before	0	0
loans, two years before	0	0
loans, three years before	0	0
loans, four years before	0	0
loans, prior	0	0
loans, revolving	0	0
Loans receivable	0	0
Consumer Portfolio Segment [Member]
loans, current year	3,682	9,959
loans, one year before	7,511	7,609
loans, two years before	6,727	1,774
loans, three years before	1,513	1,870
loans, four years before	1,800	2,372
loans, prior	6,773	4,891
loans, revolving	13,104	14,259
Loans receivable	41,110	42,734
Current period gross charge-offs, year one		0
Current period gross charge-offs, year two		1
Current period gross charge-offs, year three		0
Current period gross charge-offs, year four		0
Current period gross charge-offs, year five		0
Current period gross charge-offs, prior		49
Current period gross charge-offs, revolving		0
Current period gross charge-offs, total	(0)	50
Consumer Portfolio Segment [Member] | Pass [Member]
loans, current year	3,663
loans, one year before	7,483
loans, two years before	6,698
loans, three years before	1,391
loans, four years before	1,800
loans, prior	6,676
loans, revolving	13,020
Loans receivable	40,731
Consumer Portfolio Segment [Member] | Unclassified [Member]
loans, current year		9,913
loans, one year before		7,583
loans, two years before		1,606
loans, three years before		1,870
loans, four years before		2,369
loans, prior		4,778
loans, revolving		14,170
Loans receivable		42,289
Consumer Portfolio Segment [Member] | Special Mention [Member]
loans, current year	19	20
loans, one year before	0	0
loans, two years before	0	0
loans, three years before	0	0
loans, four years before	0	0
loans, prior	0	0
loans, revolving	0	0
Loans receivable	19	20
Consumer Portfolio Segment [Member] | Substandard [Member]
loans, current year	0	8
loans, one year before	7	26
loans, two years before	29	52
loans, three years before	109	0
loans, four years before	0	3
loans, prior	97	113
loans, revolving	28	30
Loans receivable	270	232
Consumer Portfolio Segment [Member] | Doubtful [Member]
loans, current year	0	15
loans, one year before	14	0
loans, two years before	0	0
loans, three years before	0	0
loans, four years before	0	0
loans, prior	0	0
loans, revolving	19	19
Loans receivable	33	34
Consumer Portfolio Segment [Member] | Loss [Member]
loans, current year	0	3
loans, one year before	7	0
loans, two years before	0	116
loans, three years before	13	0
loans, four years before	0	0
loans, prior	0	0
loans, revolving	37	40
Loans receivable	57	159
Commercial Portfolio Segment [Member]
loans, current year	1,836	14,107
loans, one year before	13,334	7,450
loans, two years before	6,817	3,691
loans, three years before	3,340	3,421
loans, four years before	3,054	228
loans, prior	438	319
loans, revolving	34,860	31,902
Loans receivable	63,679	61,118
Current period gross charge-offs, total	(0)
Commercial Portfolio Segment [Member] | Pass [Member]
loans, current year	1,776
loans, one year before	12,060
loans, two years before	6,376
loans, three years before	3,198
loans, four years before	2,960
loans, prior	407
loans, revolving	33,475
Loans receivable	60,252
Commercial Portfolio Segment [Member] | Unclassified [Member]
loans, current year		12,404
loans, one year before		6,967
loans, two years before		3,539
loans, three years before		3,317
loans, four years before		217
loans, prior		288
loans, revolving		30,160
Loans receivable		56,892
Commercial Portfolio Segment [Member] | Special Mention [Member]
loans, current year	60	0
loans, one year before	0	0
loans, two years before	0	0
loans, three years before	0	0
loans, four years before	0	0
loans, prior	0	0
loans, revolving	171	0
Loans receivable	231	0
Commercial Portfolio Segment [Member] | Substandard [Member]
loans, current year	0	1,703
loans, one year before	1,274	483
loans, two years before	441	152
loans, three years before	142	104
loans, four years before	94	11
loans, prior	31	31
loans, revolving	1,214	1,742
Loans receivable	3,196	4,226
Commercial Portfolio Segment [Member] | Doubtful [Member]
loans, current year	0	0
loans, one year before	0	0
loans, two years before	0	0
loans, three years before	0	0
loans, four years before	0	0
loans, prior	0	0
loans, revolving	0	0
Loans receivable	0	0
Commercial Portfolio Segment [Member] | Loss [Member]
loans, current year	0	0
loans, one year before	0	0
loans, two years before	0	0
loans, three years before	0	0
loans, four years before	0	0
loans, prior	0	0
loans, revolving	0	0
Loans receivable	$ 0	$ 0