Note 4 - Mortgage Servicing Rights (Details Textual) - USD ($)	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Fees and Commissions, Mortgage Banking and Servicing	$ 20,068,000	$ 16,770,000
Unpaid Principal Balance of Loans Serviced for Others	257,100,000		$ 238,700,000
Servicing Asset at Amortized Cost, Fair Value	2,500,000		$ 2,200,000
Proceeds from Sale of Mortgage Servicing Rights (MSR)	0	3,530,000
Mortgage Servicing Rights, Underlying Financing Receivable		318,400,000
Mortgage Servicing Rights, Underlying Financing Receivable, Book Value		2,900,000
Gain (Loss) on Sales of Mortgage-Backed Securities (MBS)		601,000
Residential Portfolio Segment [Member] | One to Four Family [Member]
Financial Receivable Originated for Sale	477,800,000	415,700,000
Fees and Commissions, Mortgage Banking and Servicing	$ 20,100,000	$ 16,800,000