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Loans and Allowance for Loan Losses - Loans Outstanding and Aging Analysis (Details) | 12 Months Ended |
--- | --- | ---
Dec. 31, 2017 USD ($) loan | Dec. 31, 2016 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Total past due | $ 2,331,000 | $ 502,000
Current | 1,676,682,000 | 1,486,114,000
Total loans | 1,679,013,000 | 1,486,616,000
Non-accrual loans | $ 406,000 | 145,000
Number of purchase credit impaired (PCI) loans with unpaid balances | loan | 3 |
Unpaid balances on purchase credit impaired (PCI) loans | $ 131,000 |
Purchased Credit Impaired (PCI) loans no longer accreting interest | 0 | 0
Purchased Credit-impaired (PCI) loans accreting interest | 2,100,000 | 2,900,000
Deferred loan fees | 818,000 | 883,000
Unaccreted purchase discounts on non-PCI loans | 1,200,000 | 1,800,000
30-59 days past due |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Total past due | 684,000 | 362,000
60-89 days past due |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Total past due | 1,340,000 | 49,000
90 days or more past due |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Total past due | 307,000 | 91,000
Commercial | Commercial and industrial |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Total past due | 1,340,000 | 283,000
Current | 234,495,000 | 218,332,000
Total loans | 235,835,000 | 218,615,000
Non-accrual loans | 0 | 0
Commercial | Commercial and industrial | 30-59 days past due |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Total past due | 0 | 283,000
Commercial | Commercial and industrial | 60-89 days past due |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Total past due | 1,340,000 | 0
Commercial | Commercial and industrial | 90 days or more past due |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Total past due | 0 | 0
Commercial real estate | Commercial real estate, owner-occupied |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Total past due | 0 | 0
Current | 300,963,000 | 247,713,000
Total loans | 300,963,000 | 247,713,000
Non-accrual loans | 0 | 0
Commercial real estate | Commercial real estate, owner-occupied | 30-59 days past due |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Total past due | 0 | 0
Commercial real estate | Commercial real estate, owner-occupied | 60-89 days past due |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Total past due | 0 | 0
Commercial real estate | Commercial real estate, owner-occupied | 90 days or more past due |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Total past due | 0 | 0
Commercial real estate | Commercial real estate, investor |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Total past due | 0 | 0
Current | 822,984,000 | 724,228,000
Total loans | 822,984,000 | 724,228,000
Non-accrual loans | 0 | 0
Commercial real estate | Commercial real estate, investor | 30-59 days past due |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Total past due | 0 | 0
Commercial real estate | Commercial real estate, investor | 60-89 days past due |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Total past due | 0 | 0
Commercial real estate | Commercial real estate, investor | 90 days or more past due |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Total past due | 0 | 0
Commercial real estate | Construction |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Total past due | 0 | 0
Current | 63,828,000 | 74,809,000
Total loans | 63,828,000 | 74,809,000
Non-accrual loans | 0 | 0
Commercial real estate | Construction | 30-59 days past due |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Total past due | 0 | 0
Commercial real estate | Construction | 60-89 days past due |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Total past due | 0 | 0
Commercial real estate | Construction | 90 days or more past due |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Total past due | 0 | 0
Residential loans | Home equity |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Total past due | 406,000 | 168,000
Current | 132,061,000 | 117,039,000
Total loans | 132,467,000 | 117,207,000
Non-accrual loans | 406,000 | 91,000
Residential loans | Home equity | 30-59 days past due |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Total past due | 99,000 | 77,000
Residential loans | Home equity | 60-89 days past due |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Total past due | 0 | 0
Residential loans | Home equity | 90 days or more past due |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Total past due | 307,000 | 91,000
Residential loans | Other residential |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Total past due | 255,000 | 0
Current | 95,271,000 | 78,549,000
Total loans | 95,526,000 | 78,549,000
Non-accrual loans | 0 | 0
Residential loans | Other residential | 30-59 days past due |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Total past due | 255,000 | 0
Residential loans | Other residential | 60-89 days past due |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Total past due | 0 | 0
Residential loans | Other residential | 90 days or more past due |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Total past due | 0 | 0
Consumer loans | Installment and other consumer |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Total past due | 330,000 | 51,000
Current | 27,080,000 | 25,444,000
Total loans | 27,410,000 | 25,495,000
Non-accrual loans | 0 | 54,000
Consumer loans | Installment and other consumer | 30-59 days past due |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Total past due | 330,000 | 2,000
Consumer loans | Installment and other consumer | 60-89 days past due |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Total past due | 0 | 49,000
Consumer loans | Installment and other consumer | 90 days or more past due |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Total past due | $ 0 | $ 0

X
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- Definition The undiscounted sum of all amounts, including amounts deemed principal, interest, fees, penalties, and other under the loan, owed to the investor at the reporting date, whether or not currently due and whether or not any such amounts have been written or charged off by the investor. This relates to loans accounted for as debt securities, with evidence of deterioration of credit quality since origination that were acquired by completion of a transfer for which it is probable, at acquisition, that the investor will be unable to collect all contractually required payments receivable. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 30 -Section 50 -Paragraph 2 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=82894903&loc=d3e15032-111544 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 30 -Section 15 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=82894507&loc=d3e13503-111538 + Details
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