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Loans and Allowance for Loan Losses - Loans by Credit Quality Indicators (Detail) (USD $) | Sep. 30, 2013 | Dec. 31, 2012 | Sep. 30, 2012
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Financing Receivable Credit Quality Indicator [Line Items] |  |  |
Total loans | $ 1,075,487,000 | $ 1,041,189,000 | $ 1,035,288,000
Commercial and Industrial [Member] |  |  |
Financing Receivable Credit Quality Indicator [Line Items] |  |  |
Total loans | 286,887,000 | 285,322,000 |
Commercial and Industrial [Member] | Grades 1-4 [Member] |  |  |
Financing Receivable Credit Quality Indicator [Line Items] |  |  |
Total loans | 208,750,000 | 180,314,000 |
Commercial and Industrial [Member] | Grades 5-7 [Member] |  |  |
Financing Receivable Credit Quality Indicator [Line Items] |  |  |
Total loans | 75,339,000 | 101,832,000 |
Commercial and Industrial [Member] | Grades 8-9 [Member] |  |  |
Financing Receivable Credit Quality Indicator [Line Items] |  |  |
Total loans | 2,798,000 | 3,176,000 |
Commercial Vacant Land, Land Development, and Residential Construction [Member] |  |  |
Financing Receivable Credit Quality Indicator [Line Items] |  |  |
Total loans | 40,741,000 | 48,099,000 |
Commercial Vacant Land, Land Development, and Residential Construction [Member] | Grades 1-4 [Member] |  |  |
Financing Receivable Credit Quality Indicator [Line Items] |  |  |
Total loans | 8,089,000 | 6,526,000 |
Commercial Vacant Land, Land Development, and Residential Construction [Member] | Grades 5-7 [Member] |  |  |
Financing Receivable Credit Quality Indicator [Line Items] |  |  |
Total loans | 27,022,000 | 37,697,000 |
Commercial Vacant Land, Land Development, and Residential Construction [Member] | Grades 8-9 [Member] |  |  |
Financing Receivable Credit Quality Indicator [Line Items] |  |  |
Total loans | 5,630,000 | 3,876,000 |
Commercial Real Estate - Owner Occupied [Member] |  |  |
Financing Receivable Credit Quality Indicator [Line Items] |  |  |
Total loans | 258,656,000 | 259,277,000 |
Commercial Real Estate - Owner Occupied [Member] | Grades 1-4 [Member] |  |  |
Financing Receivable Credit Quality Indicator [Line Items] |  |  |
Total loans | 157,824,000 | 150,467,000 |
Commercial Real Estate - Owner Occupied [Member] | Grades 5-7 [Member] |  |  |
Financing Receivable Credit Quality Indicator [Line Items] |  |  |
Total loans | 97,819,000 | 102,988,000 |
Commercial Real Estate - Owner Occupied [Member] | Grades 8-9 [Member] |  |  |
Financing Receivable Credit Quality Indicator [Line Items] |  |  |
Total loans | 3,013,000 | 5,822,000 |
Commercial Real Estate - Non-Owner Occupied [Member] |  |  |
Financing Receivable Credit Quality Indicator [Line Items] |  |  |
Total loans | 368,301,000 | 324,886,000 |
Commercial Real Estate - Non-Owner Occupied [Member] | Grades 1-4 [Member] |  |  |
Financing Receivable Credit Quality Indicator [Line Items] |  |  |
Total loans | 205,586,000 | 154,127,000 |
Commercial Real Estate - Non-Owner Occupied [Member] | Grades 5-7 [Member] |  |  |
Financing Receivable Credit Quality Indicator [Line Items] |  |  |
Total loans | 130,040,000 | 128,041,000 |
Commercial Real Estate - Non-Owner Occupied [Member] | Grades 8-9 [Member] |  |  |
Financing Receivable Credit Quality Indicator [Line Items] |  |  |
Total loans | 32,675,000 | 42,718,000 |
Commercial Real Estate - Multi-Family and Residential Rental [Member] |  |  |
Financing Receivable Credit Quality Indicator [Line Items] |  |  |
Total loans | 53,178,000 | 50,922,000 |
Commercial Real Estate - Multi-Family and Residential Rental [Member] | Grades 1-4 [Member] |  |  |
Financing Receivable Credit Quality Indicator [Line Items] |  |  |
Total loans | 31,755,000 | 24,015,000 |
Commercial Real Estate - Multi-Family and Residential Rental [Member] | Grades 5-7 [Member] |  |  |
Financing Receivable Credit Quality Indicator [Line Items] |  |  |
Total loans | 18,230,000 | 22,082,000 |
Commercial Real Estate - Multi-Family and Residential Rental [Member] | Grades 8-9 [Member] |  |  |
Financing Receivable Credit Quality Indicator [Line Items] |  |  |
Total loans | 3,193,000 | 4,825,000 |
Retail Home Equity and Other [Member] |  |  |
Financing Receivable Credit Quality Indicator [Line Items] |  |  |
Total loans | 36,575,000 | 38,917,000 |
Retail 1-4 Family Mortgages [Member] |  |  |
Financing Receivable Credit Quality Indicator [Line Items] |  |  |
Total loans | $ 31,149,000 | $ 33,766,000 |

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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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