Individually Impaired Loans by Class of Loans (Detail) (USD $)
In Thousands, unless otherwise specified | 3 Months Ended | 6 Months Ended | |
|---|
Jun. 30, 2012 | Jun. 30, 2012 | Jun. 30, 2011 | Dec. 31, 2011 |
|---|
| Financing Receivable, Impaired [Line Items] | | | | |
| Unpaid Principal Balance | $ 39,221 | $ 39,221 | $ 34,371 | $ 38,326 |
| Recorded Investment | 36,525 | 36,525 | 30,191 | 35,261 |
| Allowance for Loan Losses Allocated | 7,516 | 7,516 | 7,666 | 7,443 |
| Average Recorded Investment | 37,530 | 37,214 | 28,494 | |
| Interest Income Recognized | 205 | 444 | 324 | |
| Interest Received | 169 | 390 | 286 | |
Commercial | | | | |
| Financing Receivable, Impaired [Line Items] | | | | |
| Recorded Investment | 865 | 865 | | 917 |
| Allowance for Loan Losses Allocated | 138 | 138 | | 224 |
Residential real estate | | | | |
| Financing Receivable, Impaired [Line Items] | | | | |
| Recorded Investment | 7,670 | 7,670 | | 6,100 |
| Allowance for Loan Losses Allocated | 870 | 870 | | 477 |
Nonresidential real estate | | | | |
| Financing Receivable, Impaired [Line Items] | | | | |
| Recorded Investment | 19,913 | 19,913 | | 20,390 |
| Allowance for Loan Losses Allocated | 2,279 | 2,279 | | 2,994 |
Construction | | | | |
| Financing Receivable, Impaired [Line Items] | | | | |
| Recorded Investment | 8,077 | 8,077 | | 7,854 |
| Allowance for Loan Losses Allocated | 4,229 | 4,229 | | 3,748 |
Impaired Financing Receivables with No Related Allowance | Commercial | | | | |
| Financing Receivable, Impaired [Line Items] | | | | |
| Unpaid Principal Balance | 349 | 349 | 722 | 350 |
| Recorded Investment | 309 | 309 | 432 | 310 |
| Allowance for Loan Losses Allocated | 0 | 0 | 0 | 0 |
| Average Recorded Investment | 309 | 309 | 371 | |
| Interest Income Recognized | 0 | 0 | 0 | |
| Interest Received | 0 | 0 | 0 | |
Impaired Financing Receivables with No Related Allowance | Residential real estate | Home Equity Line of Credit | | | | |
| Financing Receivable, Impaired [Line Items] | | | | |
| Unpaid Principal Balance | 50 | 50 | 0 | 50 |
| Recorded Investment | 50 | 50 | 0 | 50 |
| Allowance for Loan Losses Allocated | 0 | 0 | 0 | 0 |
| Average Recorded Investment | 50 | 50 | 0 | |
| Interest Income Recognized | 0 | 0 | 0 | |
| Interest Received | 0 | 0 | 0 | |
Impaired Financing Receivables with No Related Allowance | Residential real estate | Multi Family | | | | |
| Financing Receivable, Impaired [Line Items] | | | | |
| Unpaid Principal Balance | 0 | 0 | 0 | 538 |
| Recorded Investment | 0 | 0 | 0 | 538 |
| Allowance for Loan Losses Allocated | 0 | 0 | 0 | 0 |
| Average Recorded Investment | 264 | 398 | 17 | |
| Interest Income Recognized | 0 | 0 | 0 | |
| Interest Received | 0 | 0 | 0 | |
Impaired Financing Receivables with No Related Allowance | Residential real estate | Residential Real Estate Other Financing Receivable | | | | |
| Financing Receivable, Impaired [Line Items] | | | | |
| Unpaid Principal Balance | 2,060 | 2,060 | 2,529 | 1,703 |
| Recorded Investment | 2,045 | 2,045 | 2,529 | 1,703 |
| Allowance for Loan Losses Allocated | 0 | 0 | 0 | 0 |
| Average Recorded Investment | 2,059 | 1,973 | 1,337 | |
| Interest Income Recognized | 0 | 0 | 0 | |
| Interest Received | 0 | 0 | 0 | |
Impaired Financing Receivables with No Related Allowance | Nonresidential real estate | Commercial Mortgage Loans, Owner Occupied | | | | |
| Financing Receivable, Impaired [Line Items] | | | | |
| Unpaid Principal Balance | 188 | 188 | 341 | 1,101 |
| Recorded Investment | 188 | 188 | 218 | 1,101 |
| Allowance for Loan Losses Allocated | 0 | 0 | 0 | 0 |
| Average Recorded Investment | 574 | 802 | 143 | |
| Interest Income Recognized | 0 | 0 | 0 | |
| Interest Received | 0 | 0 | 0 | |
Impaired Financing Receivables with No Related Allowance | Nonresidential real estate | Commercial Mortgage Loans, Non Owner Occupied | | | | |
| Financing Receivable, Impaired [Line Items] | | | | |
| Unpaid Principal Balance | 1,894 | 1,894 | 1,196 | 2,122 |
| Recorded Investment | 1,892 | 1,892 | 1,190 | 2,116 |
| Allowance for Loan Losses Allocated | 0 | 0 | 0 | 0 |
| Average Recorded Investment | 2,317 | 2,373 | 867 | |
| Interest Income Recognized | 0 | 0 | 0 | |
| Interest Received | 0 | 0 | 0 | |
Impaired Financing Receivables with No Related Allowance | Construction | | | | |
| Financing Receivable, Impaired [Line Items] | | | | |
| Unpaid Principal Balance | 655 | 655 | 1,757 | 356 |
| Recorded Investment | 355 | 355 | 928 | 319 |
| Allowance for Loan Losses Allocated | 0 | 0 | 0 | 0 |
| Average Recorded Investment | 178 | 169 | 464 | |
| Interest Income Recognized | 0 | 0 | 0 | |
| Interest Received | 0 | 0 | 0 | |
Impaired Financing Receivables with Related Allowance | Commercial | | | | |
| Financing Receivable, Impaired [Line Items] | | | | |
| Unpaid Principal Balance | 557 | 557 | 3,616 | 733 |
| Recorded Investment | 557 | 557 | 3,361 | 607 |
| Allowance for Loan Losses Allocated | 138 | 138 | 1,320 | 224 |
| Average Recorded Investment | 1,001 | 1,013 | 2,230 | |
| Interest Income Recognized | 2 | 3 | 7 | |
| Interest Received | 1 | 1 | 4 | |
Impaired Financing Receivables with Related Allowance | Residential real estate | Home Equity Line of Credit | | | | |
| Financing Receivable, Impaired [Line Items] | | | | |
| Unpaid Principal Balance | 137 | 137 | 0 | 0 |
| Recorded Investment | 137 | 137 | 0 | 0 |
| Allowance for Loan Losses Allocated | 137 | 137 | 0 | 0 |
| Average Recorded Investment | 137 | 103 | 0 | |
| Interest Income Recognized | 0 | 0 | 0 | |
| Interest Received | 0 | 0 | 0 | |
Impaired Financing Receivables with Related Allowance | Residential real estate | Multi Family | | | | |
| Financing Receivable, Impaired [Line Items] | | | | |
| Unpaid Principal Balance | 2,115 | 2,115 | 870 | 0 |
| Recorded Investment | 1,784 | 1,784 | 870 | 0 |
| Allowance for Loan Losses Allocated | 241 | 241 | 247 | 0 |
| Average Recorded Investment | 892 | 446 | 871 | |
| Interest Income Recognized | 11 | 11 | 28 | |
| Interest Received | 11 | 11 | 19 | |
Impaired Financing Receivables with Related Allowance | Residential real estate | Residential Real Estate Other Financing Receivable | | | | |
| Financing Receivable, Impaired [Line Items] | | | | |
| Unpaid Principal Balance | 3,729 | 3,729 | 2,679 | 3,859 |
| Recorded Investment | 3,654 | 3,654 | 2,660 | 3,809 |
| Allowance for Loan Losses Allocated | 492 | 492 | 581 | 477 |
| Average Recorded Investment | 3,642 | 3,681 | 2,610 | |
| Interest Income Recognized | 21 | 45 | 36 | |
| Interest Received | 17 | 40 | 34 | |
Impaired Financing Receivables with Related Allowance | Nonresidential real estate | Commercial Mortgage Loans, Owner Occupied | | | | |
| Financing Receivable, Impaired [Line Items] | | | | |
| Unpaid Principal Balance | 9,009 | 9,009 | 897 | 10,771 |
| Recorded Investment | 9,008 | 9,008 | 897 | 9,798 |
| Allowance for Loan Losses Allocated | 1,124 | 1,124 | 178 | 1,477 |
| Average Recorded Investment | 9,037 | 9,235 | 1,503 | |
| Interest Income Recognized | 78 | 158 | 1 | |
| Interest Received | 77 | 156 | 1 | |
Impaired Financing Receivables with Related Allowance | Nonresidential real estate | Commercial Mortgage Loans, Non Owner Occupied | | | | |
| Financing Receivable, Impaired [Line Items] | | | | |
| Unpaid Principal Balance | 9,644 | 9,644 | 9,332 | 8,476 |
| Recorded Investment | 8,824 | 8,824 | 7,915 | 7,375 |
| Allowance for Loan Losses Allocated | 1,155 | 1,155 | 1,753 | 1,517 |
| Average Recorded Investment | 8,246 | 7,884 | 9,252 | |
| Interest Income Recognized | 47 | 109 | 125 | |
| Interest Received | 22 | 72 | 120 | |
Impaired Financing Receivables with Related Allowance | Construction | | | | |
| Financing Receivable, Impaired [Line Items] | | | | |
| Unpaid Principal Balance | 8,834 | 8,834 | 10,432 | 8,267 |
| Recorded Investment | 7,722 | 7,722 | 9,191 | 7,535 |
| Allowance for Loan Losses Allocated | 4,229 | 4,229 | 3,587 | 3,748 |
| Average Recorded Investment | 8,824 | 8,778 | 8,829 | |
| Interest Income Recognized | 46 | 118 | 127 | |
| Interest Received | $ 41 | $ 110 | $ 108 | |