Note 6 - Loans Receivable, Net and Allowance for Loan Losses - Impaired Loans by Loan Portfolio Class (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
Mar. 31, 2022	Dec. 31, 2021
Recorded investment	$ 1,863	$ 140
Unpaid principal balance	1,863	140
Average recorded investment	1,863	224
Interest income recognized	39	12
Real Estate Portfolio Segment [Member] \| One-to-four Family Residential Owner Occupied Loans [Member]
Recorded investment, with no related allowance recorded	0	0
Unpaid principal balance, with no related allowance recorded	0	0
Average recorded investment, with no related allowance recorded	0	66
Interest income recognized, with no related allowance recorded		0
Recorded investment, with an allowance recorded	0
Unpaid principal balance, with an allowance recorded	0
Average recorded investment, with an allowance recorded	0
Recorded investment	0	0
Unpaid principal balance	0	0
Average recorded investment	0	66
Interest income recognized		0
Real Estate Portfolio Segment [Member] \| One-to-four Family Residential Non-owner Occupied Loans [Member]
Recorded investment, with no related allowance recorded	9	9
Unpaid principal balance, with no related allowance recorded	9	9
Average recorded investment, with no related allowance recorded	9	9
Interest income recognized, with no related allowance recorded		0
Recorded investment, with an allowance recorded	0
Unpaid principal balance, with an allowance recorded	0
Average recorded investment, with an allowance recorded	0
Recorded investment	9	9
Unpaid principal balance	9	9
Average recorded investment	9	9
Interest income recognized		0
Real Estate Portfolio Segment [Member] \| Multi-family (Five Or More) Residential Loans [Member]
Recorded investment, with no related allowance recorded	1,723
Unpaid principal balance, with no related allowance recorded	1,723
Average recorded investment, with no related allowance recorded	1,723
Interest income recognized, with no related allowance recorded	36
Recorded investment, with an allowance recorded	0
Unpaid principal balance, with an allowance recorded	0
Average recorded investment, with an allowance recorded	0
Recorded investment	1,723
Unpaid principal balance	1,723
Average recorded investment	1,723
Interest income recognized	36
Real Estate Portfolio Segment [Member] \| Commercial Real Estate Loans [Member]
Recorded investment, with no related allowance recorded	131	131
Unpaid principal balance, with no related allowance recorded	131	131
Average recorded investment, with no related allowance recorded	131	131
Interest income recognized, with no related allowance recorded	3	12
Recorded investment, with an allowance recorded	0
Unpaid principal balance, with an allowance recorded	0
Average recorded investment, with an allowance recorded	0
Recorded investment	131	131
Unpaid principal balance	131	131
Average recorded investment	131	131
Interest income recognized	3	12
Real Estate Portfolio Segment [Member] \| Construction Loans [Member]
Recorded investment, with no related allowance recorded	0
Unpaid principal balance, with no related allowance recorded	0
Average recorded investment, with no related allowance recorded	0
Recorded investment, with an allowance recorded	0
Unpaid principal balance, with an allowance recorded	0
Recorded investment	0
Unpaid principal balance	0
Real Estate Portfolio Segment [Member] \| Home Equity Loan [Member]
Recorded investment, with no related allowance recorded	0
Unpaid principal balance, with no related allowance recorded	0
Average recorded investment, with no related allowance recorded	0
Recorded investment, with an allowance recorded	0
Unpaid principal balance, with an allowance recorded	0
Recorded investment	0
Unpaid principal balance	0
Commercial Portfolio Segment [Member]
Recorded investment, with no related allowance recorded	0
Unpaid principal balance, with no related allowance recorded	0
Average recorded investment, with no related allowance recorded	0	$ 18
Recorded investment, with an allowance recorded	0
Unpaid principal balance, with an allowance recorded	0
Recorded investment	0
Unpaid principal balance	0
Average recorded investment	0
Consumer Portfolio Segment [Member]
Recorded investment, with no related allowance recorded	0
Unpaid principal balance, with no related allowance recorded	0
Average recorded investment, with no related allowance recorded	0
Recorded investment, with an allowance recorded	0
Unpaid principal balance, with an allowance recorded	0
Recorded investment	0
Unpaid principal balance	$ 0

Average amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 15
-Subparagraph (c)(1)
-URI https://asc.fasb.org/extlink&oid=123577603&loc=d3e5212-111524

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 17
-URI https://asc.fasb.org/extlink&oid=123577603&loc=d3e5258-111524

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-SubTopic 10
-Section 50
-Paragraph 17
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