Non-accrual Loans and Loans Past Due Over 90 Days Still on Accrual by Class (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-Accrual Loan	$ 20,436	$ 23,306
Loans Past Due 90 Days or More and Still Accruing Interest	616
Real Estate Construction
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-Accrual Loan	1,911	2,521
Loans Past Due 90 Days or More and Still Accruing Interest	455
Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-Accrual Loan	505	373
Home Equity
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-Accrual Loan	1,880	3,603
Residential Real Estate | Residential Real Estate - Owner Occupied
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-Accrual Loan	11,636	12,183
Loans Past Due 90 Days or More and Still Accruing Interest	158
Residential Real Estate | Residential Real Estate - Non Owner Occupied
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-Accrual Loan	1,582	1,565
Commercial Real Estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-Accrual Loan	2,808	3,032
Consumer | Other Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-Accrual Loan	114	29
Loans Past Due 90 Days or More and Still Accruing Interest	$ 3