Financial Instruments with Off-Balance Sheet Risk and Derivatives (Summary Of Financial Instruments With Off-Balance Sheet Credit Risk) (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
Disclosure Summary Of Financial Instruments With Off Balance Sheet Credit Risk [Line Items]
Total Commitments to extend credit and available credit lines	$ 1,194,255,000	$ 1,068,764,000
Commercial
Disclosure Summary Of Financial Instruments With Off Balance Sheet Credit Risk [Line Items]
Total Commitments to extend credit and available credit lines	212,628,000	184,083,000
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	100,264,000	100,826,000
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	12,667,000	13,908,000
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	810,552,000	710,202,000
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	$ 58,144,000	$ 59,745,000