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Allowance for Loan and Lease Losses and Reserve for Unfunded Commitments - Summary of TDR's by Loan Category (Details) - USD ($) $ in Thousands | 12 Months Ended
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Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
Financing Receivable Modifications [Line Items] |  |  |
Number of Loans | 10 | 5 | 6
Pre-Modification Outstanding Recorded Investment | $ 3,117 | $ 1,154 | $ 2,741
Post-Modification Outstanding Recorded Investment | 2,630 | $ 1,154 | $ 2,741
Charge-offs | 487 |  |
Specific Reserves | $ 357 |  |
Commercial Real Estate |  |  |
Financing Receivable Modifications [Line Items] |  |  |
Number of Loans | 5 | 2 | 2
Pre-Modification Outstanding Recorded Investment | $ 1,655 | $ 898 | $ 979
Post-Modification Outstanding Recorded Investment | 1,655 | $ 898 | $ 979
Specific Reserves | $ 111 |  |
Commercial and Industrial |  |  |
Financing Receivable Modifications [Line Items] |  |  |
Number of Loans | 3 |  |
Pre-Modification Outstanding Recorded Investment | $ 1,246 |  |
Post-Modification Outstanding Recorded Investment | 759 |  |
Charge-offs | 487 |  |
Specific Reserves | $ 246 |  |
Residential Real Estate |  |  |
Financing Receivable Modifications [Line Items] |  |  |
Number of Loans | 2 | 3 | 4
Pre-Modification Outstanding Recorded Investment | $ 216 | $ 256 | $ 1,762
Post-Modification Outstanding Recorded Investment | $ 216 | $ 256 | $ 1,762

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- Definition Number of financing receivables that have been 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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