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Loans and Loans Held for Sale - Restructured Loans for Periods Presented (Detail) $ in Thousands | 3 Months Ended | 6 Months Ended | 12 Months Ended
--- | --- | --- | ---
Jun. 30, 2015 USD ($) SecurityLoan | Jun. 30, 2014 USD ($) SecurityLoan | Jun. 30, 2015 USD ($) SecurityLoan | Jun. 30, 2014 USD ($) SecurityLoan | Dec. 31, 2014 USD ($)
Financing Receivable, Modifications [Line Items] |  |  |  |  |  |  |  |  |
Threshold period of satisfactory performance for TDR to be restored to accruing status |  |  |  |  | 6 months |  |  |  |
Restructured loans | $ 796 | [1] | $ 229 | [1] | $ 5,381 | [2] | $ 2,019 | [1] |
Number of TDRs returned to accruing status | SecurityLoan | 6 |  | 0 |  | 6 |  | 0 |  |
TDRs returned to accruing status | $ 300 |  |  |  | $ 300 |  |  |  |
Maximum concentration of commercial real estate and commercial construction portfolio in loans (in excess of) | 7.00% |  |  |  | 7.00% |  |  |  | 7.00%
Performing Financial Instruments [Member] |  |  |  |  |  |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |  |  |  |  |  |
Restructured loans |  |  |  |  | $ 32,559 |  |  |  | $ 36,983
Performing Financial Instruments [Member] | Commercial Real Estate [Member] |  |  |  |  |  |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |  |  |  |  |  |
Restructured loans |  |  |  |  | 13,045 |  |  |  | 16,939
Performing Financial Instruments [Member] | Commercial and Industrial [Member] |  |  |  |  |  |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |  |  |  |  |  |
Restructured loans |  |  |  |  | 7,899 |  |  |  | 8,074
Performing Financial Instruments [Member] | Construction Loans [Member] |  |  |  |  |  |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |  |  |  |  |  |
Restructured loans |  |  |  |  | 5,655 |  |  |  | 5,736
Performing Financial Instruments [Member] | Residential Mortgage [Member] |  |  |  |  |  |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |  |  |  |  |  |
Restructured loans |  |  |  |  | 2,622 |  |  |  | 2,839
Performing Financial Instruments [Member] | Home Equity [Member] |  |  |  |  |  |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |  |  |  |  |  |
Restructured loans |  |  |  |  | 3,302 |  |  |  | 3,342
Performing Financial Instruments [Member] | Consumer Borrower [Member] |  |  |  |  |  |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |  |  |  |  |  |
Restructured loans |  |  |  |  | 36 |  |  |  | 53
Nonperforming Financial Instruments [Member] |  |  |  |  |  |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |  |  |  |  |  |
Restructured loans |  |  |  |  | 8,928 |  |  |  | 5,436
Nonperforming Financial Instruments [Member] | Commercial Real Estate [Member] |  |  |  |  |  |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |  |  |  |  |  |
Restructured loans |  |  |  |  | 3,553 |  |  |  | 2,180
Nonperforming Financial Instruments [Member] | Commercial and Industrial [Member] |  |  |  |  |  |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |  |  |  |  |  |
Restructured loans |  |  |  |  | 2,226 |  |  |  | 356
Nonperforming Financial Instruments [Member] | Construction Loans [Member] |  |  |  |  |  |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |  |  |  |  |  |
Restructured loans |  |  |  |  | 1,969 |  |  |  | 1,869
Nonperforming Financial Instruments [Member] | Residential Mortgage [Member] |  |  |  |  |  |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |  |  |  |  |  |
Restructured loans |  |  |  |  | 609 |  |  |  | 459
Nonperforming Financial Instruments [Member] | Home Equity [Member] |  |  |  |  |  |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |  |  |  |  |  |
Restructured loans |  |  |  |  | 411 |  |  |  | 562
Nonperforming Financial Instruments [Member] | Consumer Borrower [Member] |  |  |  |  |  |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |  |  |  |  |  |
Restructured loans |  |  |  |  | 160 |  |  |  | 10
Financing Receivable [Member] |  |  |  |  |  |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |  |  |  |  |  |
Restructured loans |  |  |  |  | 41,487 |  |  |  | 42,419
Financing Receivable [Member] | Commercial Real Estate [Member] |  |  |  |  |  |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |  |  |  |  |  |
Restructured loans |  |  |  |  | 16,598 |  |  |  | 19,119
Financing Receivable [Member] | Commercial and Industrial [Member] |  |  |  |  |  |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |  |  |  |  |  |
Restructured loans |  |  |  |  | 10,125 |  |  |  | 8,430
Financing Receivable [Member] | Construction Loans [Member] |  |  |  |  |  |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |  |  |  |  |  |
Restructured loans |  |  |  |  | 7,624 |  |  |  | 7,605
Financing Receivable [Member] | Residential Mortgage [Member] |  |  |  |  |  |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |  |  |  |  |  |
Restructured loans |  |  |  |  | 3,231 |  |  |  | 3,298
Financing Receivable [Member] | Home Equity [Member] |  |  |  |  |  |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |  |  |  |  |  |
Restructured loans |  |  |  |  | 3,713 |  |  |  | 3,904
Financing Receivable [Member] | Consumer Borrower [Member] |  |  |  |  |  |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |  |  |  |  |  |
Restructured loans |  |  |  |  | $ 196 |  |  |  | $ 63
[1] | Excludes loans that were fully paid off or fully charged-off by period end. The pre-modification balance represents the balance outstanding prior to modification. The post-modification balance represents the outstanding balance at period end.
[2] | Excludes loans that were fully paid off or fully charged-off by period end. The pre-modification balance represents the balance outstanding prior to modification. The post-modification balance represents the outstanding balance at period end.

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