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Loans and Loans Held for Sale - Restructured Loans for Periods Presented (Details) - USD ($) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2017 | Dec. 31, 2016
Financing Receivable, Modifications [Line Items] |  |  |
Restructured loans | [1] | $ 6,142 | $ 12,192
Performing TDRs |  |  |
Financing Receivable, Modifications [Line Items] |  |  |
Restructured loans |  | 14,901 | 13,423
Performing TDRs | Commercial real estate |  |  |
Financing Receivable, Modifications [Line Items] |  |  |
Restructured loans |  | 2,579 | 2,994
Performing TDRs | Commercial and industrial |  |  |
Financing Receivable, Modifications [Line Items] |  |  |
Restructured loans |  | 3,946 | 1,387
Performing TDRs | Commercial construction |  |  |
Financing Receivable, Modifications [Line Items] |  |  |
Restructured loans |  | 2,420 | 2,966
Performing TDRs | Residential mortgage |  |  |
Financing Receivable, Modifications [Line Items] |  |  |
Restructured loans |  | 2,039 | 2,375
Performing TDRs | Home equity |  |  |
Financing Receivable, Modifications [Line Items] |  |  |
Restructured loans |  | 3,885 | 3,683
Performing TDRs | Installment and other consumer |  |  |
Financing Receivable, Modifications [Line Items] |  |  |
Restructured loans |  | 32 | 18
Nonperforming TDRs |  |  |
Financing Receivable, Modifications [Line Items] |  |  |
Restructured loans |  | 11,150 | 11,598
Nonperforming TDRs | Commercial real estate |  |  |
Financing Receivable, Modifications [Line Items] |  |  |
Restructured loans |  | 967 | 646
Nonperforming TDRs | Commercial and industrial |  |  |
Financing Receivable, Modifications [Line Items] |  |  |
Restructured loans |  | 3,197 | 4,493
Nonperforming TDRs | Commercial construction |  |  |
Financing Receivable, Modifications [Line Items] |  |  |
Restructured loans |  | 2,413 | 430
Nonperforming TDRs | Residential mortgage |  |  |
Financing Receivable, Modifications [Line Items] |  |  |
Restructured loans |  | 3,585 | 5,068
Nonperforming TDRs | Home equity |  |  |
Financing Receivable, Modifications [Line Items] |  |  |
Restructured loans |  | 979 | 954
Nonperforming TDRs | Installment and other consumer |  |  |
Financing Receivable, Modifications [Line Items] |  |  |
Restructured loans |  | 9 | 7
Total TDRs |  |  |
Financing Receivable, Modifications [Line Items] |  |  |
Restructured loans |  | 26,051 | 25,021
Total TDRs | Commercial real estate |  |  |
Financing Receivable, Modifications [Line Items] |  |  |
Restructured loans |  | 3,546 | 3,640
Total TDRs | Commercial and industrial |  |  |
Financing Receivable, Modifications [Line Items] |  |  |
Restructured loans |  | 7,143 | 5,880
Total TDRs | Commercial construction |  |  |
Financing Receivable, Modifications [Line Items] |  |  |
Restructured loans |  | 4,833 | 3,396
Total TDRs | Residential mortgage |  |  |
Financing Receivable, Modifications [Line Items] |  |  |
Restructured loans |  | 5,624 | 7,443
Total TDRs | Home equity |  |  |
Financing Receivable, Modifications [Line Items] |  |  |
Restructured loans |  | 4,864 | 4,637
Total TDRs | Installment and other consumer |  |  |
Financing Receivable, Modifications [Line Items] |  |  |
Restructured loans |  | $ 41 | $ 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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- Definition Post-modification amount of investment in financing receivables modified by troubled debt restructurings. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 33 -URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953676-111524 + Details
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