Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) (USD $) In Thousands, unless otherwise specified | Jun. 30, 2012 | Dec. 31, 2011 |
|---|---|---|
| Assets | ||
| Investment securities available-for-sale | $ 321,322 | $ 322,512 |
| Derivatives | 1,596 | 1,349 |
| Total | 322,918 | 323,861 |
| Liabilities | ||
| Derivatives | 1,596 | 1,349 |
| Total | 1,596 | 1,349 |
US Treasury and Government | ||
| Assets | ||
| Investment securities available-for-sale | 136,155 | 169,460 |
Residential Mortgage Backed Securities | ||
| Assets | ||
| Investment securities available-for-sale | 184,107 | 151,992 |
Corporate Securities | ||
| Assets | ||
| Investment securities available-for-sale | 1,060 | 1,060 |
Quoted Prices in Active Markets for Identical Assets (Level 1) | ||
| Assets | ||
| Derivatives | 0 | 0 |
| Total | 0 | 0 |
| Liabilities | ||
| Derivatives | 0 | 0 |
| Total | 0 | |
Quoted Prices in Active Markets for Identical Assets (Level 1) | US Treasury and Government | ||
| Assets | ||
| Investment securities available-for-sale | 0 | 0 |
Quoted Prices in Active Markets for Identical Assets (Level 1) | Residential Mortgage Backed Securities | ||
| Assets | ||
| Investment securities available-for-sale | 0 | 0 |
Quoted Prices in Active Markets for Identical Assets (Level 1) | Corporate Securities | ||
| Assets | ||
| Investment securities available-for-sale | 0 | 0 |
Significant Other Observable Inputs (Level 2) | ||
| Assets | ||
| Derivatives | 1,596 | 1,349 |
| Total | 321,858 | 322,801 |
| Liabilities | ||
| Derivatives | 1,596 | 1,349 |
| Total | 1,596 | 1,349 |
Significant Other Observable Inputs (Level 2) | US Treasury and Government | ||
| Assets | ||
| Investment securities available-for-sale | 136,155 | 169,460 |
Significant Other Observable Inputs (Level 2) | Residential Mortgage Backed Securities | ||
| Assets | ||
| Investment securities available-for-sale | 184,107 | 151,992 |
Significant Other Observable Inputs (Level 2) | Corporate Securities | ||
| Assets | ||
| Investment securities available-for-sale | 0 | 0 |
Significant Unobservable Inputs (Level 3) | ||
| Assets | ||
| Derivatives | 0 | 0 |
| Total | 1,060 | 1,060 |
| Liabilities | ||
| Derivatives | 0 | 0 |
| Total | 0 | 0 |
Significant Unobservable Inputs (Level 3) | US Treasury and Government | ||
| Assets | ||
| Investment securities available-for-sale | 0 | 0 |
Significant Unobservable Inputs (Level 3) | Residential Mortgage Backed Securities | ||
| Assets | ||
| Investment securities available-for-sale | 0 | 0 |
Significant Unobservable Inputs (Level 3) | Corporate Securities | ||
| Assets | ||
| Investment securities available-for-sale | $ 1,060 | $ 1,060 |