Note 3 - Loans Receivable - Allowance for Loan Losses (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Dec. 31, 2019
Beginning balance		$ 12,109	$ 9,731	$ 9,628	$ 9,533
Provision for loan losses		1,350	(170)	4,116	420
Charge-offs		(479)	(236)	(853)	(788)
Recoveries		27	118	116	278
Ending balance		13,007	9,443	13,007	9,443
Allowance for loan losses		12,109	9,443	9,628	9,533	$ 13,007	$ 9,628
General reserve						12,760	9,426
Specific reserve						247	202
Total loans						1,072,856	883,757
Loans collectively evaluated (1)	[1]					1,066,501	877,368
Loans individually evaluated (2)	[2]					6,355	6,389
Real Estate Portfolio Segment [Member]
Total loans						803,918	695,021
Real Estate Portfolio Segment [Member] | One-to-four Family Loan [Member]
Beginning balance		3,780	3,417	3,024	3,297
Provision for loan losses		62	(307)	764	(190)
Charge-offs		0	0	0	0
Recoveries		2	1	56	4
Ending balance		3,844	3,111	3,844	3,111
Allowance for loan losses		3,844	3,111	3,024	3,297	3,844	3,024
General reserve						3,791	2,993
Specific reserve						53	31
Total loans						317,755	306,014
Loans collectively evaluated (1)	[1]					313,744	303,026
Loans individually evaluated (2)	[2]					4,011	2,988
Real Estate Portfolio Segment [Member] | Multi-family Loan [Member]
Beginning balance		1,128	651	888	762
Provision for loan losses		307	(64)	547	(175)
Charge-offs		0	0	0	0
Recoveries		0	0	0	0
Ending balance		1,435	587	1,435	587
Allowance for loan losses		1,435	587	888	762	1,435	888
General reserve						1,435	887
Specific reserve						0	1
Total loans						127,569	96,098
Loans collectively evaluated (1)	[1]					127,282	95,991
Loans individually evaluated (2)	[2]					287	107
Real Estate Portfolio Segment [Member] | Commercial Real Estate [Member]
Beginning balance		3,021	2,357	2,243	2,289
Provision for loan losses		319	47	1,097	115
Charge-offs		0	0	0	0
Recoveries		0	0	0	0
Ending balance		3,340	2,404	3,340	2,404
Allowance for loan losses		3,340	2,404	2,243	2,289	3,340	2,243
General reserve						3,339	2,235
Specific reserve						1	8
Total loans						283,390	255,722
Loans collectively evaluated (1)	[1]					282,103	253,839
Loans individually evaluated (2)	[2]					1,287	1,883
Real Estate Portfolio Segment [Member] | Construction Loans [Member]
Beginning balance		738	711	399	585
Provision for loan losses		240	16	577	142
Charge-offs		0	0	0	0
Recoveries		1	1	3	1
Ending balance		979	728	979	728
Allowance for loan losses		979	728	399	585	979	399
General reserve						978	399
Specific reserve						1	0
Total loans						75,204	37,187
Loans collectively evaluated (1)	[1]					75,179	37,158
Loans individually evaluated (2)	[2]					25	29
Consumer Portfolio Segment [Member]
Total loans						145,902	147,165
Consumer Portfolio Segment [Member] | Home Equity Loan [Member]
Beginning balance		429	465	454	480
Provision for loan losses		(4)	(30)	(30)	(66)
Charge-offs		0	0	0	0
Recoveries		0	23	1	44
Ending balance		425	458	425	458
Allowance for loan losses		425	458	454	480	425	454
General reserve						421	439
Specific reserve						4	15
Total loans						34,120	35,046
Loans collectively evaluated (1)	[1]					33,983	34,775
Loans individually evaluated (2)	[2]					137	271
Consumer Portfolio Segment [Member] | Automobile and Other Loan [Member]
Beginning balance		2,252	1,790	2,261	1,611
Provision for loan losses		427	192	760	785
Charge-offs		(479)	(237)	(853)	(785)
Recoveries		24	93	56	227
Ending balance		2,224	1,838	2,224	1,838
Allowance for loan losses		2,224	1,838	2,261	1,611	2,224	2,261
General reserve						2,036	2,119
Specific reserve						188	142
Total loans						111,782	112,119
Loans collectively evaluated (1)	[1]					111,174	111,271
Loans individually evaluated (2)	[2]					608	848
Commercial Portfolio Segment [Member]
Beginning balance		463	171	208	334
Provision for loan losses		0	(13)	255	(174)
Charge-offs		0	1	0	(3)
Recoveries		0	0	0	2
Ending balance		463	159	463	159
Allowance for loan losses		463	159	208	334	463	208
General reserve						463	203
Specific reserve						0	5
Total loans						123,036	41,571
Loans collectively evaluated (1)	[1]					123,036	41,308
Loans individually evaluated (2)	[2]					0	263
Unallocated Financing Receivables [Member]
Beginning balance		298	169	151	175
Provision for loan losses		(1)	(11)	146	(17)
Charge-offs		0	0	0	0
Recoveries		0	0	0	0
Ending balance		297	158	297	158
Allowance for loan losses		$ 297	$ 158	$ 151	$ 175	297	151
General reserve						297	151
Specific reserve						0	0
Total loans						0	0
Loans collectively evaluated (1)	[1]					0	0
Loans individually evaluated (2)	[2]					$ 0	$ 0

[1] Loans collectively evaluated for general reserves.

[2] Loans individually evaluated for specific reserves.