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Allowance for Loan and Lease Losses and Reserve for Unfunded Commitments - Additional Information (Details) - USD ($) | 12 Months Ended
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Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
Loans And Leases Receivable Disclosure [Line Items] |  |  |
Increase (decrease) in allowance for loan and lease losses | $ 5,800,000 | $ 3,300,000 |
Commitments outstanding on troubled debt restructurings | 0 | 0 |
Recorded investment in troubled debt restructurings that subsequently defaulted within twelve months | 144,000 | 477,000 | $ 750,000
Troubled debt restructurings classified as non-accrual | 1,600,000 | 552,000 |
Reserve for unfunded commitments | 923,000 | 760,000 |
Provisions for unfunded commitments | 162,000 | 493,000 |
Charge-offs or recoveries related to reserve for unfunded commitments | 0 | 0 |
Acquired Impaired Loans |  |  |
Loans And Leases Receivable Disclosure [Line Items] |  |  |
Increase (decrease) in allowance for loan and lease losses | $ 2,300,000 | $ (1,700,000) |

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- Definition Charge-offs or recoveries related to the reserve for unfunded commitments. + References No definition available. + Details
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- Definition Financing receivable modifications non accrual. + References No definition available. + Details
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- Definition Provision for unfunded commitments. + References No definition available. + Details
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- Definition Reserve for unfunded commitments. + References No definition available. + Details
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- Definition Troubled debt restructurings, commitments outstanding. + References No definition available. + Details
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- Definition Amount of increase (decrease) of allowance reserve for credit loss. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03.7(d)) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 + Details
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- Definition Amount of investment related to financing receivables modified by troubled debt restructurings within the previous 12 months, for which there was a payment default. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 34 -URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953682-111524 + Details
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
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- Details
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