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Loans and Loans Held for Sale - Summary of Restructured Loans (Details) - USD ($) $ in Thousands | 3 Months Ended | 9 Months Ended | 12 Months Ended
--- | --- | --- | ---
Sep. 30, 2017 | Sep. 30, 2016 | Sep. 30, 2017 | Sep. 30, 2016 | Dec. 31, 2016
Financing Receivable, Modifications [Line Items] |  |  |  |  |  |
Restructured loans | [1] | $ 1,471 | $ 5,005 | $ 4,522 | $ 15,775 |
Performing TDRs |  |  |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |  |  |
Restructured loans |  |  |  | 15,605 |  | $ 13,423
Performing TDRs | Commercial Real Estate |  |  |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |  |  |
Restructured loans |  |  |  | 2,618 |  | 2,994
Performing TDRs | Commercial and Industrial |  |  |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |  |  |
Restructured loans |  |  |  | 4,063 |  | 1,387
Performing TDRs | Commercial Construction |  |  |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |  |  |
Restructured loans |  |  |  | 2,914 |  | 2,966
Performing TDRs | Residential Mortgage |  |  |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |  |  |
Restructured loans |  |  |  | 2,096 |  | 2,375
Performing TDRs | Home Equity |  |  |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |  |  |
Restructured loans |  |  |  | 3,871 |  | 3,683
Performing TDRs | Installment and Other Consumer |  |  |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |  |  |
Restructured loans |  |  |  | 43 |  | 18
Nonperforming TDRs |  |  |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |  |  |
Restructured loans |  |  |  | 10,203 |  | 11,598
Nonperforming TDRs | Commercial Real Estate |  |  |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |  |  |
Restructured loans |  |  |  | 1,083 |  | 646
Nonperforming TDRs | Commercial and Industrial |  |  |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |  |  |
Restructured loans |  |  |  | 3,580 |  | 4,493
Nonperforming TDRs | Commercial Construction |  |  |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |  |  |
Restructured loans |  |  |  | 421 |  | 430
Nonperforming TDRs | Residential Mortgage |  |  |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |  |  |
Restructured loans |  |  |  | 4,095 |  | 5,068
Nonperforming TDRs | Home Equity |  |  |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |  |  |
Restructured loans |  |  |  | 1,013 |  | 954
Nonperforming TDRs | Installment and Other Consumer |  |  |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |  |  |
Restructured loans |  |  |  | 11 |  | 7
Total TDRs |  |  |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |  |  |
Restructured loans |  |  |  | 25,808 |  | 25,021
Total TDRs | Commercial Real Estate |  |  |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |  |  |
Restructured loans |  |  |  | 3,701 |  | 3,640
Total TDRs | Commercial and Industrial |  |  |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |  |  |
Restructured loans |  |  |  | 7,643 |  | 5,880
Total TDRs | Commercial Construction |  |  |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |  |  |
Restructured loans |  |  |  | 3,335 |  | 3,396
Total TDRs | Residential Mortgage |  |  |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |  |  |
Restructured loans |  |  |  | 6,191 |  | 7,443
Total TDRs | Home Equity |  |  |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |  |  |
Restructured loans |  |  |  | 4,884 |  | 4,637
Total TDRs | Installment and Other Consumer |  |  |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |  |  |
Restructured loans |  |  |  | $ 54 |  | $ 25
[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.

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