Note 7 - Loans and the Allowance for Loan Losses - (Details Textual)		12 Months Ended
	May 01, 2020 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Loans and Leases Receivable, Deferred Income, Total		$ 7,700,000	$ 10,200,000
Loans and Leases Receivable Reclassified from Overdraft		2,400,000	623,000
Loans Receivable, Unpaid Principal Balance		461,800,000	430,000,000.0
Servicing Asset, Total		1,400,000	1,400,000
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Carrying Amount, Net		51,220,000	64,260,000
Loans and Leases Receivable, Net of Deferred Income, Total		3,189,608,000	2,991,355,000
Financing Receivable, 90 Days or More Past Due, Still Accruing		222,000	1,523,000
Financing Receivable, Nonaccrual		12,868,000	9,063,000
Impaired Financing Receivable, Interest Income, Accrual Method, Total		$ 334,000	$ 335,000
Financing Receivable, Troubled Debt Restructuring, Subsequent Default, Number of Contracts		3	1
Financing Receivable, Troubled Debt Restructuring, Subsequent Default		$ 154,000	$ 34,000	$ 0
Financing Receivable, Principal and Interest, Deferred Payments			829,100,000
Financing Receivable Accrued Interest Receivable, Loans Deferrals		$ 6,000,000.0	$ 8,400,000
COVID 19 [Member]
Financing Receivable, Number of Payment Deferrals		1,600
Financing Receivable, Deferred Payments		$ 522,000,000.0
Number of Principal and Interest Payment, Deferrals Within the Deferral Period		0	121
Outstanding Balance of Loans Within the Deferral Period			$ 98,100,000
Financing Receivable, Interest Only Deferred Payments			$ 94,800,000
Modified Loans [Member]
Financing Receivable, Modifications, Number of Contracts			7
Financing Receivable, Troubled Debt Restructuring, Postmodification			$ 4,000,000.0
Minden Bancorp and Richland State Bancorp [Member] | Performing Financial Instruments [Member]
Loans and Leases Receivable, Deferred Income, Total		$ 3,500,000	9,800,000
Loans Receivable, Fair Value Disclosure		379,000,000.0	750,600,000
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Carrying Amount, Net		51,200,000	64,300,000
Loans and Leases Receivable, Net of Deferred Income, Total		331,300,000	696,200,000
Pedestal [Member]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Receivables	$ 893,295,000
Pedestal [Member] | Financial Asset Acquired and No Credit Deterioration [Member] | Loans and Leases Receivables Acquired [Member]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Receivables	818,700,000
Pedestal [Member] | Financial Asset Acquired with Credit Deterioration [Member] | Loans and Leases Receivables Acquired [Member]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Receivables	74,600,000
Pedestal [Member] | Performing Financial Instruments [Member] | Loans and Leases Receivables Acquired [Member]
Financing Receivable, Purchased with Credit Deterioration, Discount (Premium)	$ 11,500,000
Commercial Real Estate Portfolio Segment [Member] | SBA CARES Act Paycheck Protection Program [Member]
Loans and Leases Receivable, Gross, Total		5,400,000	313,900,000
Consumer Portfolio Segment [Member]
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Carrying Amount, Net		918,000	1,879,000
Loans and Leases Receivable, Net of Deferred Income, Total		122,599,000	110,122,000
Financing Receivable, 90 Days or More Past Due, Still Accruing		18,000	22,000
Financing Receivable, Nonaccrual		$ 289,000	297,000
Consumer Portfolio Segment [Member] | SBA CARES Act Paycheck Protection Program [Member]
Loans and Leases Receivable, Gross, Total			1,600,000
Loans and Leases Receivable, Deferred Income, Total			$ 6,200,000