Note 4 - Loans and Allowance for Credit Losses on Loans (Details Textual) Pure in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2022 USD ($)	Sep. 30, 2021 USD ($)	Sep. 30, 2022 USD ($)	Sep. 30, 2021 USD ($)	Mar. 07, 2022 USD ($)	Dec. 31, 2021 USD ($)	May 31, 2021 USD ($)
Financing Receivable, Accrued Interest, after Allowance for Credit Loss		$ 13,000,000		$ 13,000,000			$ 11,000,000
Financing Receivable, before Allowance for Credit Loss, Total	[1]	5,072,877,000		5,072,877,000			4,169,303,000
Loans and Leases Receivable, Related Parties, Ending Balance		73,000,000		73,000,000			54,000,000
Financing Receivable, after Allowance for Credit Loss, Total		5,002,794,000		5,002,794,000			4,115,405,000
Financing Receivable, Purchased with Credit Deterioration, Interest Income		1,100,000	$ 341,000	4,000,000.0	$ 450,000
Financing Receivable, Nonaccrual, Interest Income		$ 0	$ 0	$ 0	$ 0
Financing Receivable, Modifications, Number of Contracts		0	0	0	0
Financing Receivable, Troubled Debt Restructuring, Subsequent Default, Number of Contracts		0	0	0	0
Mortgage Loans in Process of Foreclosure, Amount		$ 786,000		$ 786,000			917,000
Asset Pledged as Collateral [Member] | Federal Home Loan Bank Advances [Member]
Financing Receivable, before Allowance for Credit Loss, Total		2,720,000,000		2,720,000,000			$ 2,200,000,000
Commonwealth [Member]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Loans, Gross						$ 632,404,000
Commonwealth [Member] | Financial Asset Acquired with Credit Deterioration [Member]
Financing Receivable, after Allowance for Credit Loss, Total		66,000,000		66,000,000
Kentucky Bancshares [Member]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Loans, Gross								$ 755,175,000
Kentucky Bancshares [Member] | Financial Asset Acquired with Credit Deterioration [Member]
Financing Receivable, after Allowance for Credit Loss, Total		$ 13,000,000		$ 13,000,000

[1] Total loans are presented inclusive of premiums, discounts and net loan origination fees and costs.