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Loans and Loans Held for Sale - Restructured Loans During Periods Presented (Detail) $ in Thousands | 3 Months Ended | 9 Months Ended
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Sep. 30, 2016 USD ($) contract | Sep. 30, 2015 USD ($) contract | Sep. 30, 2016 USD ($) contract | Sep. 30, 2015 USD ($) contract
Financing Receivable, Modifications [Line Items] |  |  |  |  |  |  |  |  |
Number of Loans | contract |  | 14 |  | 14 |  | 52 |  | 41 |
Pre-Modification Outstanding Recorded Investment | [1] | $ 4,951 |  | $ 1,593 |  | $ 18,305 |  | $ 7,001 |
Post-Modification Outstanding Recorded Investment | [1] | 5,003 |  | 1,578 |  | 15,775 |  | 5,353 |
Total Difference in Recorded Investment |  | $ 52 |  | $ (15) |  | $ (2,530) |  | $ (1,648) |
Interest rate reduction |  |  |  |  |  |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |  |  |  |  |  |
Number of Loans | contract |  | 1 |  | 0 |  | 1 |  |  |
Pre-Modification Outstanding Recorded Investment | [1] | $ 250 |  |  |  | $ 250 |  |  |
Post-Modification Outstanding Recorded Investment | [1] | 248 |  | $ 0 |  | 248 |  |  |
Total Difference in Recorded Investment |  | $ (2) |  | $ 0 |  | $ (2) |  | $ 0 |
Maturity date extension |  |  |  |  |  |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |  |  |  |  |  |
Number of Loans | contract |  | 2 |  | 4 |  | 15 |  | 6 |
Pre-Modification Outstanding Recorded Investment | [1] | $ 4,105 |  | $ 1,257 |  | $ 6,974 |  | $ 2,108 |
Post-Modification Outstanding Recorded Investment | [1] | 4,162 |  | 1,252 |  | 6,948 |  | 2,042 |
Total Difference in Recorded Investment |  | $ 57 |  | $ (5) |  | $ (26) |  | $ (66) |
Principal forgiveness |  |  |  |  |  |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |  |  |  |  |  |
Number of Loans | contract |  |  |  |  |  | 0 |  | 1 |
Pre-Modification Outstanding Recorded Investment | [1] |  |  |  |  | $ 0 |  | $ 400 |
Post-Modification Outstanding Recorded Investment | [1] |  |  |  |  | 0 |  | 273 |
Total Difference in Recorded Investment |  |  |  |  |  | $ 0 |  | $ (127) |
Principal deferral |  |  |  |  |  |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |  |  |  |  |  |
Number of Loans | contract |  |  |  |  |  | 8 |  | 9 |
Pre-Modification Outstanding Recorded Investment | [1] |  |  |  |  | $ 9,026 |  | $ 3,616 |
Post-Modification Outstanding Recorded Investment | [1] |  |  |  |  | 6,574 |  | 2,204 |
Total Difference in Recorded Investment |  |  |  |  |  | $ (2,452) |  | $ (1,412) |
Chapter 7 bankruptcy |  |  |  |  |  |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |  |  |  |  |  |
Number of Loans | contract | [2] | 10 |  | 8 |  | 26 |  | 21 |
Pre-Modification Outstanding Recorded Investment | [1],[2] | $ 316 |  | $ 198 |  | $ 1,645 |  | $ 514 |
Post-Modification Outstanding Recorded Investment | [1],[2] | 313 |  | 188 |  | 1,597 |  | 467 |
Total Difference in Recorded Investment | [2] | $ (3) |  | $ (10) |  | $ (48) |  | $ (47) |
Maturity date extension and interest rate reduction |  |  |  |  |  |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |  |  |  |  |  |
Number of Loans | contract |  | 1 |  | 2 |  | 2 |  | 4 |
Pre-Modification Outstanding Recorded Investment | [1] | $ 280 |  | $ 138 |  | $ 410 |  | $ 363 |
Post-Modification Outstanding Recorded Investment | [1] | 280 |  | 138 |  | 408 |  | 367 |
Total Difference in Recorded Investment |  | $ 0 |  | $ 0 |  | $ (2) |  | $ 4 |
Commercial and Industrial | Maturity date extension |  |  |  |  |  |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |  |  |  |  |  |
Number of Loans | contract |  | 2 |  | 0 |  | 5 |  | 1 |
Pre-Modification Outstanding Recorded Investment | [1] | $ 4,105 |  | $ 0 |  | $ 4,860 |  | $ 780 |
Post-Modification Outstanding Recorded Investment | [1] | 4,162 |  | 0 |  | 4,891 |  | 720 |
Total Difference in Recorded Investment |  | $ 57 |  | $ 0 |  | $ 31 |  | $ (60) |
Commercial and Industrial | Principal forgiveness |  |  |  |  |  |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |  |  |  |  |  |
Number of Loans | contract |  |  |  |  |  | 0 |  | 1 |
Pre-Modification Outstanding Recorded Investment | [1] |  |  |  |  | $ 0 |  | $ 400 |
Post-Modification Outstanding Recorded Investment | [1] |  |  |  |  | 0 |  | 273 |
Total Difference in Recorded Investment |  |  |  |  |  | $ 0 |  | $ (127) |
Commercial and Industrial | Principal deferral |  |  |  |  |  |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |  |  |  |  |  |
Number of Loans | contract |  |  |  |  |  | 5 |  | 6 |
Pre-Modification Outstanding Recorded Investment | [1] |  |  |  |  | $ 985 |  | $ 661 |
Post-Modification Outstanding Recorded Investment | [1] |  |  |  |  | 985 |  | 363 |
Total Difference in Recorded Investment |  |  |  |  |  | $ 0 |  | $ (298) |
Commercial and Industrial | Chapter 7 bankruptcy |  |  |  |  |  |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |  |  |  |  |  |
Number of Loans | contract | [2] |  |  |  |  | 0 |  | 1 |
Pre-Modification Outstanding Recorded Investment | [1],[2] |  |  |  |  | $ 0 |  | $ 3 |
Post-Modification Outstanding Recorded Investment | [1],[2] |  |  |  |  | 0 |  | 0 |
Total Difference in Recorded Investment | [2] |  |  |  |  | $ 0 |  | $ (3) |
Commercial Real Estate | Interest rate reduction |  |  |  |  |  |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |  |  |  |  |  |
Number of Loans | contract |  | 1 |  | 0 |  | 1 |  | 0 |
Pre-Modification Outstanding Recorded Investment |  | $ 250 | [1] | $ 0 | [1] | $ 250 | [1] | $ 0 |
Post-Modification Outstanding Recorded Investment |  | 248 | [1] | 0 | [1] | 248 | [1] | 0 |
Total Difference in Recorded Investment |  | $ (2) |  | $ 0 |  | $ (2) |  | $ 0 |
Commercial Real Estate | Maturity date extension |  |  |  |  |  |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |  |  |  |  |  |
Number of Loans | contract |  | 0 |  | 1 |  | 0 |  | 1 |
Pre-Modification Outstanding Recorded Investment | [1] | $ 0 |  | $ 264 |  | $ 0 |  | $ 264 |
Post-Modification Outstanding Recorded Investment | [1] | 0 |  | 260 |  | 0 |  | 260 |
Total Difference in Recorded Investment |  | $ 0 |  | $ (4) |  | $ 0 |  | $ (4) |
Commercial Real Estate | Principal deferral |  |  |  |  |  |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |  |  |  |  |  |
Number of Loans | contract |  |  |  |  |  | 1 |  | 2 |
Pre-Modification Outstanding Recorded Investment | [1] |  |  |  |  | $ 4,721 |  | $ 2,851 |
Post-Modification Outstanding Recorded Investment | [1] |  |  |  |  | 2,270 |  | 1,841 |
Total Difference in Recorded Investment |  |  |  |  |  | $ (2,451) |  | $ (1,010) |
Commercial Real Estate | Chapter 7 bankruptcy |  |  |  |  |  |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |  |  |  |  |  |
Number of Loans | contract | [2] |  |  |  |  | 1 |  | 0 |
Pre-Modification Outstanding Recorded Investment | [1],[2] |  |  |  |  | $ 709 |  | $ 0 |
Post-Modification Outstanding Recorded Investment | [1],[2] |  |  |  |  | 681 |  | 0 |
Total Difference in Recorded Investment | [2] |  |  |  |  | $ (28) |  | $ 0 |
Commercial Construction | Maturity date extension |  |  |  |  |  |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |  |  |  |  |  |
Number of Loans | contract |  | 0 |  | 2 |  | 5 |  | 2 |
Pre-Modification Outstanding Recorded Investment | [1] | $ 0 |  | $ 813 |  | $ 1,357 |  | $ 813 |
Post-Modification Outstanding Recorded Investment | [1] | 0 |  | 812 |  | 1,302 |  | 812 |
Total Difference in Recorded Investment |  | $ 0 |  | $ (1) |  | $ (55) |  | $ (1) |
Commercial Construction | Principal deferral |  |  |  |  |  |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |  |  |  |  |  |
Number of Loans | contract |  |  |  |  |  | 0 |  | 1 |
Pre-Modification Outstanding Recorded Investment | [1] |  |  |  |  | $ 0 |  | $ 104 |
Post-Modification Outstanding Recorded Investment | [1] |  |  |  |  | 0 |  | 0 |
Total Difference in Recorded Investment |  |  |  |  |  | $ 0 |  | $ (104) |
Residential Mortgage | Maturity date extension |  |  |  |  |  |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |  |  |  |  |  |
Number of Loans | contract |  | 0 |  | 1 |  | 1 |  | 1 |
Pre-Modification Outstanding Recorded Investment | [1] | $ 0 |  | $ 180 |  | $ 483 |  | $ 180 |
Post-Modification Outstanding Recorded Investment | [1] | 0 |  | 180 |  | 483 |  | 180 |
Total Difference in Recorded Investment |  | $ 0 |  | $ 0 |  | $ 0 |  | $ 0 |
Residential Mortgage | Principal deferral |  |  |  |  |  |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |  |  |  |  |  |
Number of Loans | contract |  |  |  |  |  | 1 |  | 0 |
Pre-Modification Outstanding Recorded Investment | [1] |  |  |  |  | $ 3,273 |  | $ 0 |
Post-Modification Outstanding Recorded Investment | [1] |  |  |  |  | 3,273 |  | 0 |
Total Difference in Recorded Investment |  |  |  |  |  | $ 0 |  | $ 0 |
Residential Mortgage | Chapter 7 bankruptcy |  |  |  |  |  |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |  |  |  |  |  |
Number of Loans | contract |  | 3 | [1] | 2 | [2] | 7 | [2] | 2 | [2]
Pre-Modification Outstanding Recorded Investment | [1],[2] | $ 153 |  | $ 74 |  | $ 439 |  | $ 74 |
Post-Modification Outstanding Recorded Investment | [1],[2] | 152 |  | 74 |  | 433 |  | 74 |
Total Difference in Recorded Investment | [2] | $ (1) |  | $ 0 |  | $ (6) |  | $ 0 |
Residential Mortgage | Maturity date extension and interest rate reduction |  |  |  |  |  |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |  |  |  |  |  |
Number of Loans | contract |  | 1 |  | 0 |  | 1 |  | 2 |
Pre-Modification Outstanding Recorded Investment | [1] | $ 280 |  | $ 0 |  | $ 280 |  | $ 225 |
Post-Modification Outstanding Recorded Investment | [1] | 280 |  | 0 |  | 280 |  | 229 |
Total Difference in Recorded Investment |  | $ 0 |  | $ 0 |  | $ 0 |  | $ 4 |
Home Equity | Maturity date extension |  |  |  |  |  |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |  |  |  |  |  |
Number of Loans | contract |  |  |  |  |  | 4 |  | 1 |
Pre-Modification Outstanding Recorded Investment | [1] |  |  |  |  | $ 274 |  | $ 71 |
Post-Modification Outstanding Recorded Investment | [1] |  |  |  |  | 272 |  | 70 |
Total Difference in Recorded Investment |  |  |  |  |  | $ (2) |  | $ (1) |
Home Equity | Principal deferral |  |  |  |  |  |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |  |  |  |  |  |
Number of Loans | contract |  |  |  |  |  | 1 |  | 0 |
Pre-Modification Outstanding Recorded Investment | [1] |  |  |  |  | $ 47 |  | $ 0 |
Post-Modification Outstanding Recorded Investment | [1] |  |  |  |  | 46 |  | 0 |
Total Difference in Recorded Investment |  |  |  |  |  | $ (1) |  | $ 0 |
Home Equity | Chapter 7 bankruptcy |  |  |  |  |  |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |  |  |  |  |  |
Number of Loans | contract | [2] | 7 |  | 5 |  | 16 |  | 17 |
Pre-Modification Outstanding Recorded Investment | [1],[2] | $ 163 |  | $ 115 |  | $ 481 |  | $ 428 |
Post-Modification Outstanding Recorded Investment | [1],[2] | 161 |  | 110 |  | 470 |  | 389 |
Total Difference in Recorded Investment | [2] | $ (2) |  | $ (5) |  | $ (11) |  | $ (39) |
Home Equity | Maturity date extension and interest rate reduction |  |  |  |  |  |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |  |  |  |  |  |
Number of Loans | contract |  | 0 |  | 2 |  | 1 |  | 2 |
Pre-Modification Outstanding Recorded Investment | [1] | $ 0 |  | $ 138 |  | $ 130 |  | $ 138 |
Post-Modification Outstanding Recorded Investment | [1] | 0 |  | 138 |  | 128 |  | 138 |
Total Difference in Recorded Investment |  | $ 0 |  | $ 0 |  | $ (2) |  | $ 0 |
Installment and Other Consumer | Chapter 7 bankruptcy |  |  |  |  |  |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |  |  |  |  |  |
Number of Loans | contract | [2] |  |  | 1 |  | 2 |  | 1 |
Pre-Modification Outstanding Recorded Investment | [1],[2] |  |  | $ 9 |  | $ 16 |  | $ 9 |
Post-Modification Outstanding Recorded Investment | [1],[2] |  |  | 4 |  | 13 |  | 4 |
Total Difference in Recorded Investment | [2] |  |  | $ (5) |  | $ (3) |  | $ (5) |
[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] | Chapter 7 bankruptcy loans where the debt has been legally discharged through the bankruptcy court and not reaffirmed.

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