Loans and Allowance for Loan Losses - Recorded Principal Balance of Nonaccrual Loans (Detail) (USD $)	Sep. 30, 2013	Dec. 31, 2012
Financing Receivable Recorded Investment Nonaccrual Loans [Line Items]
Total nonaccrual loans	$ 10,526,000	$ 18,970,000
Commercial and Industrial [Member]
Financing Receivable Recorded Investment Nonaccrual Loans [Line Items]
Total nonaccrual loans	1,581,000	1,677,000
Commercial Vacant Land, Land Development, and Residential Construction [Member]
Financing Receivable Recorded Investment Nonaccrual Loans [Line Items]
Total nonaccrual loans	922,000	2,194,000
Commercial Real Estate - Owner Occupied [Member]
Financing Receivable Recorded Investment Nonaccrual Loans [Line Items]
Total nonaccrual loans	570,000	2,087,000
Commercial Real Estate - Non-Owner Occupied [Member]
Financing Receivable Recorded Investment Nonaccrual Loans [Line Items]
Total nonaccrual loans	4,642,000	9,010,000
Commercial Real Estate - Multi-Family and Residential Rental [Member]
Financing Receivable Recorded Investment Nonaccrual Loans [Line Items]
Total nonaccrual loans	764,000	2,021,000
Commercial Loans [Member]
Financing Receivable Recorded Investment Nonaccrual Loans [Line Items]
Total nonaccrual loans	8,479,000	16,989,000
Retail Home Equity and Other [Member]
Financing Receivable Recorded Investment Nonaccrual Loans [Line Items]
Total nonaccrual loans	805,000	889,000
Retail 1-4 Family Mortgages [Member]
Financing Receivable Recorded Investment Nonaccrual Loans [Line Items]
Total nonaccrual loans	1,242,000	1,092,000
Retail Loans [Member]
Financing Receivable Recorded Investment Nonaccrual Loans [Line Items]
Total nonaccrual loans	$ 2,047,000	$ 1,981,000