| **Allowance for Loan Losses - Financing Receivable and Allowance Element by Class (Details) - USD ($) $ in Thousands** | Dec. 31, 2016 | Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013 |
|------------------------------------------------------------------------------------------------------------------------|---------------|---------------|---------------|---------------|
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                       |          |          |          |          |
| Allowance for loan losses                                                                                              | $ 10,138      | $ 9,916       | $ 10,344      | $ 11,514      |
| Commercial | Real Estate                                                                                               |          |          |          |          |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                       |          |          |          |          |
| Allowance for loan losses                                                                                              | 3,988         | 3,120         | 3,532         | 4,602         |
| Commercial | Construction                                                                                              |          |          |          |          |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                       |          |          |          |          |
| Allowance for loan losses                                                                                              | 396           | 580           | 823           | 575           |
| Commercial | Other                                                                                                     |          |          |          |          |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                       |          |          |          |          |
| Allowance for loan losses                                                                                              | 1,780         | 1,452         | 1,505         | 2,276         |
| Municipal                                                                                                              |          |          |          |          |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                       |          |          |          |          |
| Allowance for loan losses                                                                                              | 18            | 17            | 15            | 15            |
| Residential | Construction                                                                                             |          |          |          |          |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                       |          |          |          |          |
| Allowance for loan losses                                                                                              | 44            | 24            | 20            | 21            |
| Residential | Term                                                                                                     |          |          |          |          |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                       |          |          |          |          |
| Allowance for loan losses                                                                                              | 1,288         | 1,391         | 1,185         | 1,099         |
| Home Equity LIne of Credit                                                                                             |          |          |          |          |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                       |          |          |          |          |
| Allowance for loan losses                                                                                              | 807           | 893           | 1,060         | 675           |
| Consumer                                                                                                               |          |          |          |          |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                       |          |          |          |          |
| Allowance for loan losses                                                                                              | 559           | 566           | 542           | 573           |
| Unallocated                                                                                                            |          |          |          |          |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                       |          |          |          |          |
| Allowance for loan losses                                                                                              | 1,258         | 1,873         | $ 1,662       | $ 1,678       |
| Specific Reserves on Loans Evaluated Individually for Impairment                                                       |          |          |          |          |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                       |          |          |          |          |
| Allowance for loan losses                                                                                              | 974           | 754           |          |          |
| Specific Reserves on Loans Evaluated Individually for Impairment | Commercial | Real Estate                            |          |          |          |          |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                       |          |          |          |          |
| Allowance for loan losses                                                                                              | 505           | 89            |          |          |
| Specific Reserves on Loans Evaluated Individually for Impairment | Commercial | Construction                           |          |          |          |          |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                       |          |          |          |          |
| Allowance for loan losses                                                                                              | 100           | 302           |          |          |
| Specific Reserves on Loans Evaluated Individually for Impairment | Commercial | Other                                  |          |          |          |          |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                       |          |          |          |          |
| Allowance for loan losses                                                                                              | 39            | 8             |          |          |
| Specific Reserves on Loans Evaluated Individually for Impairment | Municipal                                           |          |          |          |          |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                       |          |          |          |          |
| Allowance for loan losses                                                                                              | 0             | 0             |          |          |
| Specific Reserves on Loans Evaluated Individually for Impairment | Residential | Construction                          |          |          |          |          |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                       |          |          |          |          |
| Allowance for loan losses                                                                                              | 0             | 0             |          |          |
| Specific Reserves on Loans Evaluated Individually for Impairment | Residential | Term                                  |          |          |          |          |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                       |          |          |          |          |
| Allowance for loan losses                                                                                              | 304           | 326           |          |          |
| Specific Reserves on Loans Evaluated Individually for Impairment | Home Equity LIne of Credit                          |          |          |          |          |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                       |          |          |          |          |
| Allowance for loan losses                                                                                              | 26            | 29            |          |          |
| Specific Reserves on Loans Evaluated Individually for Impairment | Consumer                                            |          |          |          |          |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                       |          |          |          |          |
| Allowance for loan losses                                                                                              | 0             | 0             |          |          |
| Specific Reserves on Loans Evaluated Individually for Impairment | Unallocated                                         |          |          |          |          |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                       |          |          |          |          |
| Allowance for loan losses                                                                                              | 0             | 0             |          |          |
| General Reserves on Loans Based on Historical Loss Experience                                                          |          |          |          |          |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                       |          |          |          |          |
| Allowance for loan losses                                                                                              | 3,691         | 2,858         |          |          |
| General Reserves on Loans Based on Historical Loss Experience | Commercial | Real Estate                               |          |          |          |          |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                       |          |          |          |          |
| Allowance for loan losses                                                                                              | 1,471         | 893           |          |          |
| General Reserves on Loans Based on Historical Loss Experience | Commercial | Construction                              |          |          |          |          |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                       |          |          |          |          |
| Allowance for loan losses                                                                                              | 125           | 82            |          |          |
| General Reserves on Loans Based on Historical Loss Experience | Commercial | Other                                     |          |          |          |          |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                       |          |          |          |          |
| Allowance for loan losses                                                                                              | 735           | 425           |          |          |
| General Reserves on Loans Based on Historical Loss Experience | Municipal                                              |          |          |          |          |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                       |          |          |          |          |
| Allowance for loan losses                                                                                              | 0             | 0             |          |          |
| General Reserves on Loans Based on Historical Loss Experience | Residential | Construction                             |          |          |          |          |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                       |          |          |          |          |
| Allowance for loan losses                                                                                              | 25            | 14            |          |          |
| General Reserves on Loans Based on Historical Loss Experience | Residential | Term                                     |          |          |          |          |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                       |          |          |          |          |
| Allowance for loan losses                                                                                              | 563           | 613           |          |          |
| General Reserves on Loans Based on Historical Loss Experience | Home Equity LIne of Credit                             |          |          |          |          |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                       |          |          |          |          |
| Allowance for loan losses                                                                                              | 444           | 500           |          |          |
| General Reserves on Loans Based on Historical Loss Experience | Consumer                                               |          |          |          |          |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                       |          |          |          |          |
| Allowance for loan losses                                                                                              | 328           | 331           |          |          |
| General Reserves on Loans Based on Historical Loss Experience | Unallocated                                            |          |          |          |          |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                       |          |          |          |          |
| Allowance for loan losses                                                                                              | 0             | 0             |          |          |
| Reserves for Qualitative Factors                                                                                       |          |          |          |          |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                       |          |          |          |          |
| Allowance for loan losses                                                                                              | 4,215         | 4,431         |          |          |
| Reserves for Qualitative Factors | Commercial | Real Estate                                                            |          |          |          |          |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                       |          |          |          |          |
| Allowance for loan losses                                                                                              | 2,012         | 2,138         |          |          |
| Reserves for Qualitative Factors | Commercial | Construction                                                           |          |          |          |          |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                       |          |          |          |          |
| Allowance for loan losses                                                                                              | 171           | 196           |          |          |
| Reserves for Qualitative Factors | Commercial | Other                                                                  |          |          |          |          |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                       |          |          |          |          |
| Allowance for loan losses                                                                                              | 1,006         | 1,019         |          |          |
| Reserves for Qualitative Factors | Municipal                                                                           |          |          |          |          |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                       |          |          |          |          |
| Allowance for loan losses                                                                                              | 18            | 17            |          |          |
| Reserves for Qualitative Factors | Residential | Construction                                                          |          |          |          |          |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                       |          |          |          |          |
| Allowance for loan losses                                                                                              | 19            | 10            |          |          |
| Reserves for Qualitative Factors | Residential | Term                                                                  |          |          |          |          |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                       |          |          |          |          |
| Allowance for loan losses                                                                                              | 421           | 452           |          |          |
| Reserves for Qualitative Factors | Home Equity LIne of Credit                                                          |          |          |          |          |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                       |          |          |          |          |
| Allowance for loan losses                                                                                              | 337           | 364           |          |          |
| Reserves for Qualitative Factors | Consumer                                                                            |          |          |          |          |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                       |          |          |          |          |
| Allowance for loan losses                                                                                              | 231           | 235           |          |          |
| Reserves for Qualitative Factors | Unallocated                                                                         |          |          |          |          |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                       |          |          |          |          |
| Allowance for loan losses                                                                                              | 0             | 0             |          |          |
| Unallocated Reserves                                                                                                   |          |          |          |          |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                       |          |          |          |          |
| Allowance for loan losses                                                                                              | 1,258         | 1,873         |          |          |
| Unallocated Reserves | Commercial | Real Estate                                                                        |          |          |          |          |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                       |          |          |          |          |
| Allowance for loan losses                                                                                              | 0             | 0             |          |          |
| Unallocated Reserves | Commercial | Construction                                                                       |          |          |          |          |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                       |          |          |          |          |
| Allowance for loan losses                                                                                              | 0             | 0             |          |          |
| Unallocated Reserves | Commercial | Other                                                                              |          |          |          |          |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                       |          |          |          |          |
| Allowance for loan losses                                                                                              | 0             | 0             |          |          |
| Unallocated Reserves | Municipal                                                                                       |          |          |          |          |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                       |          |          |          |          |
| Allowance for loan losses                                                                                              | 0             | 0             |          |          |
| Unallocated Reserves | Residential | Construction                                                                      |          |          |          |          |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                       |          |          |          |          |
| Allowance for loan losses                                                                                              | 0             | 0             |          |          |
| Unallocated Reserves | Residential | Term                                                                              |          |          |          |          |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                       |          |          |          |          |
| Allowance for loan losses                                                                                              | 0             | 0             |          |          |
| Unallocated Reserves | Home Equity LIne of Credit                                                                      |          |          |          |          |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                       |          |          |          |          |
| Allowance for loan losses                                                                                              | 0             | 0             |          |          |
| Unallocated Reserves | Consumer                                                                                        |          |          |          |          |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                       |          |          |          |          |
| Allowance for loan losses                                                                                              | 0             | 0             |          |          |
| Unallocated Reserves | Unallocated                                                                                     |          |          |          |          |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                       |          |          |          |          |
| Allowance for loan losses                                                                                              | $ 1,258       | $ 1,873       |          |          |

| X                                                                                                                                                                                                                                                                                                                                                                                                                                |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - 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.
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|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of allowance to cover probable credit losses on loans and leases. Includes carryover of or adjustments to the allowance for loan losses in connection with business combinations. Excludes allowance for loans and leases covered under loss sharing agreements.
+ References
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