Note 10 - Commitments and Contingent Liabilities - Off Balance Sheet Commitments to Extend Credit (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Off balance sheet commitments to extend credit	$ 1,116,410	$ 1,172,933
Commercial and Industrial Loans [Member]
Off balance sheet commitments to extend credit	408,190	416,195
Construction and Development [Member]
Off balance sheet commitments to extend credit	270,144	240,503
Home Equity Loans [Member]
Off balance sheet commitments to extend credit	157,851	155,920
Credit Cards [Member]
Off balance sheet commitments to extend credit	27,688	26,439
Overdrafts [Member]
Off balance sheet commitments to extend credit	32,763	32,715
Letters of Credit [Member]
Off balance sheet commitments to extend credit	24,531	24,193
Other Off Balance Sheet Commitments [Member]
Off balance sheet commitments to extend credit	42,611	40,083
Future Loan Commitments [Member]
Off balance sheet commitments to extend credit	$ 152,632	$ 236,885