Summary Of Financial Instruments With Off-Balance Sheet Credit Risk (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Disclosure Summary Of Financial Instruments With Off Balance Sheet Credit Risk [Line Items]
Total Commitments to extend credit and available credit lines	$ 1,061,133	$ 872,764
Commercial
Disclosure Summary Of Financial Instruments With Off Balance Sheet Credit Risk [Line Items]
Total Commitments to extend credit and available credit lines	186,014	79,567
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	79,480	76,940
Residential Real Estate Mortgage
Disclosure Summary Of Financial Instruments With Off Balance Sheet Credit Risk [Line Items]
Total Commitments to extend credit and available credit lines	56,445	20,922
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	667,186	621,422
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	$ 72,008	$ 73,913