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           Components Of Net Deferred Tax Asset (Detail) (USD $) 
        In Thousands, unless otherwise specified  | 
        
           Dec. 31, 2012 
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           Dec. 31, 2011 
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           Dec. 31, 2010 
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|---|---|---|---|
| Other real estate | $ 1,064 | $ 452 | $ 646 | 
| Start-up costs | 101 | 115 | 127 | 
| Net unrealized (gains) losses on securities available for sale | (3,929) | (4,220) | (1,528) | 
| Depreciation | (509) | (489) | (206) | 
| Deferred loan fees | (237) | (176) | (72) | 
| Allowance for loan losses | 10,142 | 8,509 | 6,974 | 
| Nonqualified equity awards | 583 | 436 | 194 | 
| Other | 171 | 287 | 231 | 
| Net deferred income tax assets | $ 7,386 | $ 4,914 | $ 6,366 | 
| X | ||||||||||
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- Definition 
          The portion of the difference between the effective income tax rate and domestic federal statutory income tax rate attributable to Loan fees. No definition available. 
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- Definition 
          Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from depreciation. No definition available. 
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- Definition 
          The portion of the difference between the effective income tax rate and domestic federal statutory income tax rate attributable to Nonqualified equity awards. No definition available. 
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- Definition 
          The portion of the difference between the effective income tax rate and domestic federal statutory income tax rate attributable to Other real estate. No definition available. 
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- Definition 
          The portion of the difference between the effective income tax rate and domestic federal statutory income tax rate attributable toStart-up costs. No definition available. 
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| X | ||||||||||
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- Definition 
          Amount after allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences and carryforwards. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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| X | ||||||||||
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- Definition 
          Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from other provisions, reserves, allowances, and accruals not separately disclosed. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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| X | ||||||||||
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- Definition 
          Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from the provision for loan losses. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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| X | ||||||||||
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- Definition 
          Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from unrealized losses on available-for-sale securities. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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