Note 3 - Loans Receivable - Credit Quality Indicators by Class of Loan (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Total loans	$ 1,072,856	$ 883,757
Nonperforming Financial Instruments [Member]
Total loans	3,098	1,796
Performing Financial Instruments [Member]
Total loans	1,069,758	881,961
Pass [Member]
Total loans	1,034,082	865,674
Watch [Member]
Total loans	28,280	8,055
Special Mention [Member]
Total loans	6,465	5,078
Substandard [Member]
Total loans	4,029	4,950
Real Estate Portfolio Segment [Member]
Total loans	803,918	695,021
Real Estate Portfolio Segment [Member] | Pass [Member]
Total loans	770,368	684,434
Real Estate Portfolio Segment [Member] | Watch [Member]
Total loans	25,653	3,966
Real Estate Portfolio Segment [Member] | Special Mention [Member]
Total loans	4,812	4,132
Real Estate Portfolio Segment [Member] | Substandard [Member]
Total loans	3,085	2,489
Real Estate Portfolio Segment [Member] | One-to-four Family Loan [Member]
Total loans	317,755	306,014
Real Estate Portfolio Segment [Member] | One-to-four Family Loan [Member] | Nonperforming Financial Instruments [Member]
Total loans	1,939	698
Real Estate Portfolio Segment [Member] | One-to-four Family Loan [Member] | Performing Financial Instruments [Member]
Total loans	315,816	305,316
Real Estate Portfolio Segment [Member] | One-to-four Family Loan [Member] | Pass [Member]
Total loans	310,998	301,312
Real Estate Portfolio Segment [Member] | One-to-four Family Loan [Member] | Watch [Member]
Total loans	2,624	2,685
Real Estate Portfolio Segment [Member] | One-to-four Family Loan [Member] | Special Mention [Member]
Total loans	2,602	1,148
Real Estate Portfolio Segment [Member] | One-to-four Family Loan [Member] | Substandard [Member]
Total loans	1,531	869
Real Estate Portfolio Segment [Member] | Multi-family Loan [Member]
Total loans	127,569	96,098
Real Estate Portfolio Segment [Member] | Multi-family Loan [Member] | Nonperforming Financial Instruments [Member]
Total loans	287	0
Real Estate Portfolio Segment [Member] | Multi-family Loan [Member] | Performing Financial Instruments [Member]
Total loans	127,282	96,098
Real Estate Portfolio Segment [Member] | Multi-family Loan [Member] | Pass [Member]
Total loans	127,282	95,694
Real Estate Portfolio Segment [Member] | Multi-family Loan [Member] | Watch [Member]
Total loans	0	0
Real Estate Portfolio Segment [Member] | Multi-family Loan [Member] | Special Mention [Member]
Total loans	0	107
Real Estate Portfolio Segment [Member] | Multi-family Loan [Member] | Substandard [Member]
Total loans	287	297
Real Estate Portfolio Segment [Member] | Commercial Real Estate [Member]
Total loans	283,390	255,722
Real Estate Portfolio Segment [Member] | Commercial Real Estate [Member] | Nonperforming Financial Instruments [Member]
Total loans	166	109
Real Estate Portfolio Segment [Member] | Commercial Real Estate [Member] | Performing Financial Instruments [Member]
Total loans	283,224	255,613
Real Estate Portfolio Segment [Member] | Commercial Real Estate [Member] | Pass [Member]
Total loans	270,792	251,531
Real Estate Portfolio Segment [Member] | Commercial Real Estate [Member] | Watch [Member]
Total loans	9,233	97
Real Estate Portfolio Segment [Member] | Commercial Real Estate [Member] | Special Mention [Member]
Total loans	2,133	2,800
Real Estate Portfolio Segment [Member] | Commercial Real Estate [Member] | Substandard [Member]
Total loans	1,232	1,294
Real Estate Portfolio Segment [Member] | Construction Loans [Member]
Total loans	75,204	37,187
Real Estate Portfolio Segment [Member] | Construction Loans [Member] | Nonperforming Financial Instruments [Member]
Total loans	25	29
Real Estate Portfolio Segment [Member] | Construction Loans [Member] | Performing Financial Instruments [Member]
Total loans	75,179	37,158
Real Estate Portfolio Segment [Member] | Construction Loans [Member] | Pass [Member]
Total loans	61,296	35,897
Real Estate Portfolio Segment [Member] | Construction Loans [Member] | Watch [Member]
Total loans	13,796	1,184
Real Estate Portfolio Segment [Member] | Construction Loans [Member] | Special Mention [Member]
Total loans	77	77
Real Estate Portfolio Segment [Member] | Construction Loans [Member] | Substandard [Member]
Total loans	35	29
Consumer Portfolio Segment [Member]
Total loans	145,902	147,165
Consumer Portfolio Segment [Member] | Pass [Member]
Total loans	140,910	141,587
Consumer Portfolio Segment [Member] | Watch [Member]
Total loans	2,627	3,713
Consumer Portfolio Segment [Member] | Special Mention [Member]
Total loans	1,653	683
Consumer Portfolio Segment [Member] | Substandard [Member]
Total loans	712	1,182
Consumer Portfolio Segment [Member] | Home Equity Loan [Member]
Total loans	34,120	35,046
Consumer Portfolio Segment [Member] | Home Equity Loan [Member] | Nonperforming Financial Instruments [Member]
Total loans	74	112
Consumer Portfolio Segment [Member] | Home Equity Loan [Member] | Performing Financial Instruments [Member]
Total loans	34,046	34,934
Consumer Portfolio Segment [Member] | Home Equity Loan [Member] | Pass [Member]
Total loans	33,503	34,260
Consumer Portfolio Segment [Member] | Home Equity Loan [Member] | Watch [Member]
Total loans	394	470
Consumer Portfolio Segment [Member] | Home Equity Loan [Member] | Special Mention [Member]
Total loans	100	89
Consumer Portfolio Segment [Member] | Home Equity Loan [Member] | Substandard [Member]
Total loans	123	227
Consumer Portfolio Segment [Member] | Automobile and Other Loan [Member]
Total loans	111,782	112,119
Consumer Portfolio Segment [Member] | Automobile and Other Loan [Member] | Nonperforming Financial Instruments [Member]
Total loans	607	848
Consumer Portfolio Segment [Member] | Automobile and Other Loan [Member] | Performing Financial Instruments [Member]
Total loans	111,175	111,271
Consumer Portfolio Segment [Member] | Automobile and Other Loan [Member] | Pass [Member]
Total loans	107,407	107,327
Consumer Portfolio Segment [Member] | Automobile and Other Loan [Member] | Watch [Member]
Total loans	2,233	3,243
Consumer Portfolio Segment [Member] | Automobile and Other Loan [Member] | Special Mention [Member]
Total loans	1,553	594
Consumer Portfolio Segment [Member] | Automobile and Other Loan [Member] | Substandard [Member]
Total loans	589	955
Commercial Portfolio Segment [Member]
Total loans	123,036	41,571
Commercial Portfolio Segment [Member] | Nonperforming Financial Instruments [Member]
Total loans	0	0
Commercial Portfolio Segment [Member] | Performing Financial Instruments [Member]
Total loans	123,036	41,571
Commercial Portfolio Segment [Member] | Pass [Member]
Total loans	122,804	39,653
Commercial Portfolio Segment [Member] | Watch [Member]
Total loans	0	376
Commercial Portfolio Segment [Member] | Special Mention [Member]
Total loans	0	263
Commercial Portfolio Segment [Member] | Substandard [Member]
Total loans	$ 232	$ 1,279