Note 10 - Commitments and Contingent Liabilities - Off Balance Sheet Commitments to Extend Credit (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Off balance sheet commitments to extend credit	$ 1,439,334	$ 1,172,933
Commercial and Industrial Loans [Member]
Off balance sheet commitments to extend credit	546,098	416,195
Construction and Development [Member]
Off balance sheet commitments to extend credit	238,526	240,503
Home Equity Loans [Member]
Off balance sheet commitments to extend credit	175,649	155,920
Credit Cards [Member]
Off balance sheet commitments to extend credit	32,295	26,439
Overdrafts [Member]
Off balance sheet commitments to extend credit	33,812	32,715
Letters of Credit [Member]
Off balance sheet commitments to extend credit	22,238	24,193
Other Off Balance Sheet Commitments [Member]
Off balance sheet commitments to extend credit	47,720	40,083
Future Loan Commitments [Member]
Off balance sheet commitments to extend credit	$ 342,996	$ 236,885