Note 8 - Commitments and Off-balance Sheet Risk - Exposure to Credit Losses (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Contractual amounts of financial instruments with off-balance sheet risk	$ 2,081,842	$ 2,113,504
Standby Letters of Credit [Member]
Contractual amounts of financial instruments with off-balance sheet risk	19,540	19,393
Unused lines of Credit [Member] | Commercial Portfolio Segment [Member]
Contractual amounts of financial instruments with off-balance sheet risk	1,562,294	1,557,429
Unused lines of Credit [Member] | One to Four Family Mortgages [Member]
Contractual amounts of financial instruments with off-balance sheet risk	74,824	74,120
Unused lines of Credit [Member] | Credit Card Lines of Credit [Member]
Contractual amounts of financial instruments with off-balance sheet risk	150,098	142,096
Unused lines of Credit [Member] | Consumer Other Financing Receivable 1 [Member]
Contractual amounts of financial instruments with off-balance sheet risk	40,140	50,063
Loan Origination Commitments [Member]
Contractual amounts of financial instruments with off-balance sheet risk	$ 234,946	$ 270,403