Note 3 - Loans Receivable (Details Textual)		12 Months Ended
		Dec. 31, 2022 USD ($)		Dec. 31, 2021 USD ($)		Dec. 31, 2020 USD ($)
Percentage of Loans Secured by Residential Real Estate		76.70%
Financing Receivable, before Allowance for Credit Loss, Total		$ 1,510,178,000		$ 1,205,785,000
Loans and Leases Receivable, Related Parties, Ending Balance		2,800,000		2,500,000
Loans and Leases Receivable, Related Parties, Past Due or Impaired		0		0
Financing Receivable, Nonaccrual		4,307,000		5,574,000
Financing Receivable, 90 Days or More Past Due, Still Accruing		0		0
Financing Receivable, Allowance for Credit Loss, Ending Balance		17,757,000	[1]	15,778,000	[1]	$ 18,823,000
Loans Requiring Officers Loans Committee Review and Approval, Minimum		500,000
Minimum Amount of Potential Loan Exposure to be Reviewed by Credit Management Personnel		$ 1,000,000.0
Maximum Period of Time Loan Reviewed Under Renewal Condition (Year)		1 year
Financing Receivable, Troubled Debt Restructuring		$ 936,000		$ 3,989,000
Minimum Number of Consecutive Contractual Payments Received Prior to Consideration for a Return to Accrual Status		6
Financing Receivable, Troubled Debt Restructuring, Subsequent Default, Number of Contracts		0		0
Minimum [Member]
Period of Principal Forbearance Reduction in Interest Rate or Both Included in Typical Restructured Terms (Month)		6 months
Maximum [Member]
Period of Principal Forbearance Reduction in Interest Rate or Both Included in Typical Restructured Terms (Month)		12 months
Commercial Portfolio Segment [Member]
Financing Receivable, before Allowance for Credit Loss, Total		$ 24,934,000		$ 22,298,000
Financing Receivable, Nonaccrual		0		0
Financing Receivable, Allowance for Credit Loss, Ending Balance		267,000		427,000		642,000
Minimum Amount of Potential Loan Exposure to be Reviewed		200,000
Financing Receivable, Troubled Debt Restructuring				1,097,000
Unfunded Loan Commitment [Member]
Financing Receivable, Allowance for Credit Loss, Ending Balance		1,300,000
One to Four Family [Member] | Residential Portfolio Segment [Member]
Financing Receivable, before Allowance for Credit Loss, Total		469,567,000		300,523,000
Financing Receivable, Nonaccrual		4,209,000		5,420,000
Financing Receivable, Allowance for Credit Loss, Ending Balance		4,743,000		3,963,000		$ 5,459,000
Financing Receivable, Troubled Debt Restructuring		936,000		1,670,000
Mortgage Loans in Process of Foreclosure, Amount		795,000		1,400,000
Financial Asset, 1 to 59 Days Past Due [Member]
Financing Receivable, before Allowance for Credit Loss, Total	[2]	2,345,000		643,000
Financing Receivable, Nonaccrual		0		43,000
Financial Asset, 1 to 59 Days Past Due [Member] | Commercial Portfolio Segment [Member]
Financing Receivable, before Allowance for Credit Loss, Total	[2]	3,000		7,000
Financial Asset, 1 to 59 Days Past Due [Member] | One to Four Family [Member] | Residential Portfolio Segment [Member]
Financing Receivable, before Allowance for Credit Loss, Total	[2]	2,328,000		622,000
Financial Asset, 60 to 89 Days Past Due [Member]
Financing Receivable, before Allowance for Credit Loss, Total	[3]	233,000		2,051,000
Financing Receivable, Nonaccrual		0		347,000
Financial Asset, 60 to 89 Days Past Due [Member] | Commercial Portfolio Segment [Member]
Financing Receivable, before Allowance for Credit Loss, Total	[3]	0		0
Financial Asset, 60 to 89 Days Past Due [Member] | One to Four Family [Member] | Residential Portfolio Segment [Member]
Financing Receivable, before Allowance for Credit Loss, Total	[3]	0		2,028,000
Financial Asset, Not Past Due [Member]
Financing Receivable, before Allowance for Credit Loss, Total	[4]	1,503,917,000		1,198,723,000
Financing Receivable, Nonaccrual		624,000		816,000,000
Financial Asset, Not Past Due [Member] | Commercial Portfolio Segment [Member]
Financing Receivable, before Allowance for Credit Loss, Total	[4]	24,931,000		22,291,000
Financial Asset, Not Past Due [Member] | One to Four Family [Member] | Residential Portfolio Segment [Member]
Financing Receivable, before Allowance for Credit Loss, Total	[4]	463,621,000		293,659,000
Federal Home Loan Bank of Chicago [Member]
Federal Home Loan Bank, Advance, Total		385,700,000		475,000,000.0
Asset Pledged as Collateral [Member] | Federal Home Loan Bank Advances [Member]
Financing Receivable, before Allowance for Credit Loss, Total		$ 976,700,000		$ 886,700,000

[1] The Company adopted ASU 2016-13 as of January 1, 2022. The prior year amounts presented are calculated under the prior accounting standard.

[2] Includes $600,000 and $43,000 at March 31, 2022 and December 31, 2021, respectively, which are on non-accrual status.

[3] Includes $ - and $347,000 at March 31, 2022 and December 31, 2021, respectively, which are on non-accrual status.

[4] Includes $666,000 and $816,000 at March 31, 2022 and December 31, 2021, respectively, which are on non-accrual status.