Recorded Investment in Nonperforming Loans by Class of Loans (Detail) (USD $)
In Thousands, unless otherwise specified
Jun. 30, 2012
Dec. 31, 2011
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Nonaccrual Loans $ 7,488 $ 7,401
Loans 90+ Days Past Due Still Accruing 85 363
Total Nonperforming Loans 8,689 11,515
Nonperforming Financing Receivable
    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Total Nonperforming Loans 7,573 7,764
Residential
    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Nonaccrual Loans 2,370 2,281
Loans 90+ Days Past Due Still Accruing 0 143
Total Nonperforming Loans 5,646 7,308
Residential | Nonperforming Financing Receivable
    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Total Nonperforming Loans 2,370 2,424
Land
    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Nonaccrual Loans 41 5
Loans 90+ Days Past Due Still Accruing 0 38
Total Nonperforming Loans 209 528
Land | Nonperforming Financing Receivable
    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Total Nonperforming Loans 41 43
Construction
    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Nonaccrual Loans 265 247
Loans 90+ Days Past Due Still Accruing 0 0
Total Nonperforming Loans 265 247
Construction | Nonperforming Financing Receivable
    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Total Nonperforming Loans 265 247
Commercial Real Estate
    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Nonaccrual Loans 2,730 2,853
Loans 90+ Days Past Due Still Accruing 2 0
Total Nonperforming Loans 1,627 1,934
Commercial Real Estate | Nonperforming Financing Receivable
    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Total Nonperforming Loans 2,732 2,853
Commercial Business
    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Nonaccrual Loans 1,843 1,928
Loans 90+ Days Past Due Still Accruing 0 0
Total Nonperforming Loans 38 256
Commercial Business | Nonperforming Financing Receivable
    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Total Nonperforming Loans 1,843 1,928
Home Equity and Second Mortgage
    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Nonaccrual Loans 239 87
Loans 90+ Days Past Due Still Accruing 67 159
Total Nonperforming Loans 560 876
Home Equity and Second Mortgage | Nonperforming Financing Receivable
    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Total Nonperforming Loans 306 246
Other Consumer
    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Nonaccrual Loans 0 0
Loans 90+ Days Past Due Still Accruing 16 23
Total Nonperforming Loans 344 366
Other Consumer | Nonperforming Financing Receivable
    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Total Nonperforming Loans $ 16 $ 23