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Loans and Allowance for Loan Losses - Components of Loan Portfolio Disaggregated by Class of Loan and Percentage Change in Total Loans (Detail) (USD $) | Sep. 30, 2013 | Dec. 31, 2012 | Sep. 30, 2012
--- | --- | --- | ---
Financing Receivable, Recorded Investment [Line Items] |  |  |
Total loans | $ 1,075,487,000 | $ 1,041,189,000 | $ 1,035,288,000
Loan portfolio classes and segments as a percentage of aggregate loans | 100.00% | 100.00% |
Loans and leases receivable net of deferred income increase decrease percentage | 3.30% |  |
Commercial and Industrial [Member] |  |  |
Financing Receivable, Recorded Investment [Line Items] |  |  |
Total loans | 286,887,000 | 285,322,000 |
Loan portfolio classes and segments as a percentage of aggregate loans | 26.70% | 27.40% |
Loans and leases receivable net of deferred income increase decrease percentage | 0.50% |  |
Commercial Vacant Land, Land Development, and Residential Construction [Member] |  |  |
Financing Receivable, Recorded Investment [Line Items] |  |  |
Total loans | 40,741,000 | 48,099,000 |
Loan portfolio classes and segments as a percentage of aggregate loans | 3.80% | 4.60% |
Loans and leases receivable net of deferred income increase decrease percentage | (15.30%) |  |
Commercial Real Estate - Owner Occupied [Member] |  |  |
Financing Receivable, Recorded Investment [Line Items] |  |  |
Total loans | 258,656,000 | 259,277,000 |
Loan portfolio classes and segments as a percentage of aggregate loans | 24.10% | 24.90% |
Loans and leases receivable net of deferred income increase decrease percentage | (0.20%) |  |
Commercial Real Estate - Non-Owner Occupied [Member] |  |  |
Financing Receivable, Recorded Investment [Line Items] |  |  |
Total loans | 368,301,000 | 324,886,000 |
Loan portfolio classes and segments as a percentage of aggregate loans | 34.20% | 31.20% |
Loans and leases receivable net of deferred income increase decrease percentage | 13.40% |  |
Commercial Real Estate - Multi-Family and Residential Rental [Member] |  |  |
Financing Receivable, Recorded Investment [Line Items] |  |  |
Total loans | 53,178,000 | 50,922,000 |
Loan portfolio classes and segments as a percentage of aggregate loans | 4.90% | 4.90% |
Loans and leases receivable net of deferred income increase decrease percentage | 4.40% |  |
Commercial Loans [Member] |  |  |
Financing Receivable, Recorded Investment [Line Items] |  |  |
Total loans | 1,007,763,000 | 968,506,000 | 957,411,000
Loan portfolio classes and segments as a percentage of aggregate loans | 93.70% | 93.00% |
Loans and leases receivable net of deferred income increase decrease percentage | 4.10% |  |
Retail Home Equity and Other [Member] |  |  |
Financing Receivable, Recorded Investment [Line Items] |  |  |
Total loans | 36,575,000 | 38,917,000 |
Loan portfolio classes and segments as a percentage of aggregate loans | 3.40% | 3.70% |
Loans and leases receivable net of deferred income increase decrease percentage | (6.00%) |  |
Retail 1-4 Family Mortgages [Member] |  |  |
Financing Receivable, Recorded Investment [Line Items] |  |  |
Total loans | 31,149,000 | 33,766,000 |
Loan portfolio classes and segments as a percentage of aggregate loans | 2.90% | 3.30% |
Loans and leases receivable net of deferred income increase decrease percentage | (7.80%) |  |
Retail Loans [Member] |  |  |
Financing Receivable, Recorded Investment [Line Items] |  |  |
Total loans | $ 67,724,000 | $ 72,683,000 | $ 77,877,000
Loan portfolio classes and segments as a percentage of aggregate loans | 6.30% | 7.00% |
Loans and leases receivable net of deferred income increase decrease percentage | (6.80%) |  |

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- Definition Amount before allowance and after deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=28368275&loc=d3e5074-111524 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=28367877&loc=d3e4428-111522 + Details
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