Note 8 - Commitments and Off-balance Sheet Risk - Exposure to Credit Losses (Details) - USD ($)	Sep. 30, 2023	Dec. 31, 2022
Contractual amounts of financial instruments with off-balance sheet risk	$ 2,178,793,000	$ 1,908,294,000
Standby Letters of Credit [Member]
Contractual amounts of financial instruments with off-balance sheet risk	19,367,000	23,539,000
Unused lines of Credit [Member] | Commercial Portfolio Segment [Member]
Contractual amounts of financial instruments with off-balance sheet risk	1,603,414,000	1,283,703,000
Unused lines of Credit [Member] | One to Four Family Mortgages [Member]
Contractual amounts of financial instruments with off-balance sheet risk	74,130,000	71,972,000
Unused lines of Credit [Member] | Credit Card Lines of Credit [Member]
Contractual amounts of financial instruments with off-balance sheet risk	135,886,000	123,687,000
Unused lines of Credit [Member] | Consumer Other Financing Receivable 1 [Member]
Contractual amounts of financial instruments with off-balance sheet risk	58,486,000	75,747,000
Loan Origination Commitments [Member]
Contractual amounts of financial instruments with off-balance sheet risk	$ 287,510,000	$ 329,646,000