| 
           Financial Assets And Financial Liabilities Carried At Fair Value On A Recurring Basis (Detail) (USD $) 
        In Thousands, unless otherwise specified  | 
        
           Dec. 31, 2012 
         | 
        
           Dec. 31, 2011 
         | 
      
|---|---|---|
| Available-for-sale securities: | $ 233,877 | $ 293,809 | 
| Derivative assets | 490 | |
| 
           Fair Value Measurements Recurring [Member] 
         | 
        ||
| Total assets | 294,435 | |
| 
           Fair Value Measurements Recurring [Member] | Us Treasury and Government [Member] 
         | 
        ||
| Available-for-sale securities: | 28,386 | 99,622 | 
| 
           Fair Value Measurements Recurring [Member] | Collateralized Mortgage Backed Securities [Member] 
         | 
        ||
| Available-for-sale securities: | 73,466 | 92,580 | 
| 
           Fair Value Measurements Recurring [Member] | Us States and Political Subdivisions Debt Securities [Member] 
         | 
        ||
| Available-for-sale securities: | 118,177 | 100,526 | 
| 
           Fair Value Measurements Recurring [Member] | Corporate Debt Securities [Member] 
         | 
        ||
| Available-for-sale securities: | 13,848 | 1,081 | 
| 
           Fair Value Measurements Recurring [Member] | Interest Rate Swap [Member] 
         | 
        ||
| Derivative assets | 389 | 617 | 
| Derivative liabilities | 389 | 617 | 
| 
           Fair Value Measurements Recurring [Member] | Interest Rate Cap [Member] 
         | 
        ||
| Derivative assets | 9 | |
| 
           Fair Value Measurements Recurring [Member] | Fair Value Inputs Level 2 [Member] 
         | 
        ||
| Total assets | 294,435 | |
| 
           Fair Value Measurements Recurring [Member] | Fair Value Inputs Level 2 [Member] | Us Treasury and Government [Member] 
         | 
        ||
| Available-for-sale securities: | 28,386 | 99,622 | 
| 
           Fair Value Measurements Recurring [Member] | Fair Value Inputs Level 2 [Member] | Collateralized Mortgage Backed Securities [Member] 
         | 
        ||
| Available-for-sale securities: | 73,466 | 92,580 | 
| 
           Fair Value Measurements Recurring [Member] | Fair Value Inputs Level 2 [Member] | Us States and Political Subdivisions Debt Securities [Member] 
         | 
        ||
| Available-for-sale securities: | 118,177 | 100,526 | 
| 
           Fair Value Measurements Recurring [Member] | Fair Value Inputs Level 2 [Member] | Corporate Debt Securities [Member] 
         | 
        ||
| Available-for-sale securities: | 13,848 | 1,081 | 
| 
           Fair Value Measurements Recurring [Member] | Fair Value Inputs Level 2 [Member] | Interest Rate Swap [Member] 
         | 
        ||
| Derivative assets | 389 | 617 | 
| Derivative liabilities | 389 | 617 | 
| 
           Fair Value Measurements Recurring [Member] | Fair Value Inputs Level 2 [Member] | Interest Rate Cap [Member] 
         | 
        ||
| Derivative assets | $ 9 |