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Loans and Loans Held for Sale - Restructured Loans for Periods Presented (Detail) $ in Thousands | 3 Months Ended | 12 Months Ended
--- | --- | ---
Mar. 31, 2016 USD ($) tdr | Mar. 31, 2015 USD ($) tdr | Dec. 31, 2015 USD ($)
Financing Receivable, Modifications [Line Items] |  |  |
Threshold period of satisfactory performance for troubled debt restructuring to be restored to accruing status | 6 months |  |
Restructured loans | $ 2,614 | $ 4,585 |
Number of troubled debt restructuring loans returned back to accruing status | tdr | 0 | 0 |
Performing Financial Instruments |  |  |
Financing Receivable, Modifications [Line Items] |  |  |
Restructured loans | $ 22,761 |  | $ 23,955
Performing Financial Instruments | Commercial and Industrial |  |  |
Financing Receivable, Modifications [Line Items] |  |  |
Restructured loans | 6,280 |  | 6,321
Performing Financial Instruments | Commercial Real Estate |  |  |
Financing Receivable, Modifications [Line Items] |  |  |
Restructured loans | 6,339 |  | 6,822
Performing Financial Instruments | Commercial Construction |  |  |
Financing Receivable, Modifications [Line Items] |  |  |
Restructured loans | 4,367 |  | 5,013
Performing Financial Instruments | Residential Mortgage |  |  |
Financing Receivable, Modifications [Line Items] |  |  |
Restructured loans | 2,537 |  | 2,590
Performing Financial Instruments | Home Equity |  |  |
Financing Receivable, Modifications [Line Items] |  |  |
Restructured loans | 3,215 |  | 3,184
Performing Financial Instruments | Installment and Other Consumer |  |  |
Financing Receivable, Modifications [Line Items] |  |  |
Restructured loans | 23 |  | 25
Nonperforming Financial Instruments |  |  |
Financing Receivable, Modifications [Line Items] |  |  |
Restructured loans | 9,291 |  | 7,659
Nonperforming Financial Instruments | Commercial and Industrial |  |  |
Financing Receivable, Modifications [Line Items] |  |  |
Restructured loans | 1,695 |  | 1,570
Nonperforming Financial Instruments | Commercial Real Estate |  |  |
Financing Receivable, Modifications [Line Items] |  |  |
Restructured loans | 3,747 |  | 3,548
Nonperforming Financial Instruments | Commercial Construction |  |  |
Financing Receivable, Modifications [Line Items] |  |  |
Restructured loans | 1,742 |  | 1,265
Nonperforming Financial Instruments | Residential Mortgage |  |  |
Financing Receivable, Modifications [Line Items] |  |  |
Restructured loans | 1,193 |  | 665
Nonperforming Financial Instruments | Home Equity |  |  |
Financing Receivable, Modifications [Line Items] |  |  |
Restructured loans | 911 |  | 523
Nonperforming Financial Instruments | Installment and Other Consumer |  |  |
Financing Receivable, Modifications [Line Items] |  |  |
Restructured loans | 3 |  | 88
Financing Receivable |  |  |
Financing Receivable, Modifications [Line Items] |  |  |
Restructured loans | 32,052 |  | 31,614
Financing Receivable | Commercial and Industrial |  |  |
Financing Receivable, Modifications [Line Items] |  |  |
Restructured loans | 7,975 |  | 7,891
Financing Receivable | Commercial Real Estate |  |  |
Financing Receivable, Modifications [Line Items] |  |  |
Restructured loans | 10,086 |  | 10,370
Financing Receivable | Commercial Construction |  |  |
Financing Receivable, Modifications [Line Items] |  |  |
Restructured loans | 6,109 |  | 6,278
Financing Receivable | Residential Mortgage |  |  |
Financing Receivable, Modifications [Line Items] |  |  |
Restructured loans | 3,730 |  | 3,255
Financing Receivable | Home Equity |  |  |
Financing Receivable, Modifications [Line Items] |  |  |
Restructured loans | 4,126 |  | 3,707
Financing Receivable | Installment and Other Consumer |  |  |
Financing Receivable, Modifications [Line Items] |  |  |
Restructured loans | $ 26 |  | $ 113

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