Note 10 - Commitments and Contingent Liabilities - Off Balance Sheet Commitments to Extend Credit (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Off balance sheet commitments to extend credit	$ 1,400,661	$ 1,390,772
Commercial and Industrial Loans [Member]
Off balance sheet commitments to extend credit	585,289	555,077
Construction and Development [Member]
Off balance sheet commitments to extend credit	292,996	266,550
Home Equity Loans [Member]
Off balance sheet commitments to extend credit	177,156	175,132
Credit Cards [Member]
Off balance sheet commitments to extend credit	32,555	32,321
Overdrafts [Member]
Off balance sheet commitments to extend credit	32,917	33,564
Letters of Credit [Member]
Off balance sheet commitments to extend credit	26,326	24,425
Other Off Balance Sheet Commitments [Member]
Off balance sheet commitments to extend credit	51,935	54,385
Future Loan Commitments [Member]
Off balance sheet commitments to extend credit	$ 201,487	$ 249,318