Note 3 - Loans and Allowance for Loan Losses - Retail Credit Exposure (Details) - USD ($)	Dec. 31, 2021	Dec. 31, 2020
Loans	$ 3,453,459,000	$ 3,193,470,000
Retail Portfolio Segment [Member]
Loans	503,035,000	399,508,000
Retail Portfolio Segment [Member] | Home Equity and Other [Member]
Loans	60,488,000	61,620,000
Retail Portfolio Segment [Member] | Home Equity and Other [Member] | Performing Financial Instruments [Member]
Loans	60,369,000	61,378,000
Retail Portfolio Segment [Member] | Home Equity and Other [Member] | Nonperforming Financial Instruments [Member]
Loans	119,000	242,000
Retail Portfolio Segment [Member] | One to Four Family Mortgages [Member]
Loans	442,547,000	337,888,000
Retail Portfolio Segment [Member] | One to Four Family Mortgages [Member] | Performing Financial Instruments [Member]
Loans	440,861,000	335,559,000
Retail Portfolio Segment [Member] | One to Four Family Mortgages [Member] | Nonperforming Financial Instruments [Member]
Loans	$ 1,686,000	$ 2,329,000