Financial Instruments with Off-Balance Sheet Risk and Derivatives (Summary Of Financial Instruments With Off-Balance Sheet Credit Risk) (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Disclosure Summary Of Financial Instruments With Off Balance Sheet Credit Risk [Line Items]
Total Commitments to extend credit and available credit lines	$ 1,284,200	$ 1,194,255
Commercial
Disclosure Summary Of Financial Instruments With Off Balance Sheet Credit Risk [Line Items]
Total Commitments to extend credit and available credit lines	234,552	212,628
Real estate-development and construction
Disclosure Summary Of Financial Instruments With Off Balance Sheet Credit Risk [Line Items]
Total Commitments to extend credit and available credit lines	80,935	100,264
Real estate-residential mortgage
Disclosure Summary Of Financial Instruments With Off Balance Sheet Credit Risk [Line Items]
Total Commitments to extend credit and available credit lines	23,375	12,667
Lines of credit, principally home equity and business lines
Disclosure Summary Of Financial Instruments With Off Balance Sheet Credit Risk [Line Items]
Total Commitments to extend credit and available credit lines	879,326	810,552
Standby letters of credit
Disclosure Summary Of Financial Instruments With Off Balance Sheet Credit Risk [Line Items]
Total Commitments to extend credit and available credit lines	$ 66,012	$ 58,144