Note 7 - Loans and the Allowance for Loan Losses - (Details Textual)	12 Months Ended
	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Mar. 01, 2022 USD ($)
Loans and Leases Receivable, Deferred Income	$ 13,100,000	$ 7,700,000
Loans and Leases Receivable Reclassified from Overdraft	2,000,000.0	2,400,000
Loans Receivable, Unpaid Principal Balance	683,300,000	461,800,000
Servicing Asset, Total	1,700,000	1,400,000
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Carrying Amount, Net	49,787,000	51,220,000
Loans and Leases Receivable, Net of Deferred Income	4,606,176,000	3,189,608,000
Financing Receivable, 90 Days or More Past Due, Still Accruing	335,000	222,000
Financing Receivable, Nonaccrual	11,054,000	12,868,000
Impaired Financing Receivable, Interest Income, Accrual Method	$ 378,000	$ 334,000
Financing Receivable, Troubled Debt Restructuring, Subsequent Default, Number of Contracts	1	3
Financing Receivable, Troubled Debt Restructuring, Subsequent Default	$ 1,500,000	$ 154,000
Financing Receivable, Modifications, Number of Contracts	1	0
Financing Receivable, Troubled Debt Restructuring, Premodification	$ 3,500,000
Financing Receivable, Troubled Debt Restructuring, Postmodification	3,200,000
Financing Receivable Accrued Interest Receivable, Loans Deferrals	5,400,000	$ 6,000,000.0
COVID 19 [Member]
Financing Receivable, Deferred Payments	$ 425,200,000	$ 522,000,000.0
Number of Principal and Interest Payment, Deferrals Within the Deferral Period	0	0
Minden Bancorp and Richland State Bancorp [Member] | Performing Financial Instruments [Member]
Loans and Leases Receivable, Deferred Income	$ 3,300,000	$ 3,500,000
Loans Receivable, Acquired Loans	498,100,000	379,000,000.0
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Carrying Amount, Net	49,800,000	51,200,000
Loans and Leases Receivable, Net of Deferred Income	450,000,000.0	331,300,000
Texas Citizens Bancorp [Member]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Receivables			$ 338,027,000
Texas Citizens Bancorp [Member] | Loans and Leases Receivables Acquired [Member] | Financial Asset Acquired with Credit Deterioration [Member]
Loans and Leases Receivable, Loans Acquired With Credit Deterioration			21,500,000
Texas Citizens Bancorp [Member] | Performing Financial Instruments [Member] | Loans and Leases Receivables Acquired [Member]
Loans and Leases Receivable, Loans Acquired Without Credit Deterioration			316,500,000
Loans and Leases Receivable, Loans Acquired Without Credit Deterioration, Net Discount			$ 1,700,000
Commercial Real Estate Portfolio Segment [Member] | SBA CARES Act Paycheck Protection Program [Member]
Loans and Leases Receivable, Gross	$ 2,800,000	$ 5,400,000