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Fair Value (Details Textual) $ in Thousands | 12 Months Ended
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Dec. 31, 2017 USD ($) Property | Dec. 31, 2016 USD ($) | Dec. 31, 2015 USD ($)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |  |
Fair value assets liabilities transfers amount between level 1 and level 2 | $ 0 | $ 0 |
Impaired loans, unpaid principal balance with allowance recorded | 1,636 | 2,710 | $ 4,014
Impaired loans, allowance | 162 | 249 | 497
Provision for loan losses | 3,350 | 3,870 | $ 3,510
Troubled debt restructurings | $ 5,000 | 7,000 |
Number of properties charged down reflecting updated appraisals | Property | 1 |  |
Other real estate owned measured at fair value less costs to sell | $ 0 |  |
Write down of other real estate owned | $ 23 | 36 |
Maximum maturity period of short term borrowings | 90 days |  |
Measured Using Present Value of Cash Flows |  |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |  |
Troubled debt restructurings | $ 763 | 2,000 |
Collateral Dependent Impaired Loans |  |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |  |
Impaired loans, unpaid principal balance with allowance recorded | 851 | 727 |
Impaired loans, allowance | 109 | 173 |
Provision for loan losses | $ 272 | $ 139 |

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