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Fair Market Value of Financial Assets and Liabilities (Details) - USD ($) $ in Thousands | 3 Months Ended | 9 Months Ended | 12 Months Ended
--- | --- | --- | ---
Sep. 30, 2018 | Dec. 31, 2017 | Sep. 30, 2017 | Sep. 30, 2018 | Sep. 30, 2017 | Dec. 31, 2017
Assets Measured at Fair Value on Recurring Basis [Abstract] |  |  |  |  |  |
Available-for-sale securities, debt securities | $ 569,208 | $ 561,403 |  | $ 569,208 |  | $ 561,403
Assets measured-nonrecurring basis [Abstract] |  |  |  |  |  |
Impaired loans (collateral dependent) | 556 | 2,709 |  | 556 |  | 2,709
Reconciliation of beginning and ending balances of recurring fair value measurements recognized in balance sheet using significant unobservable (Level 3) inputs [Roll Forward] |  |  |  |  |  |
Total gains (losses) | (75) |  | $ (119) | $ 2 | $ (419) |
Minimum [Member] |  |  |  |  |  |
Other real estate owned [Abstract] |  |  |  |  |  |
Typical frequency of periodic reviews |  |  |  | 12 months |  |
Maximum [Member] |  |  |  |  |  |
Other real estate owned [Abstract] |  |  |  |  |  |
Typical frequency of periodic reviews |  |  |  | 18 months |  |
Frequency of periodic reviews in general |  |  |  | 24 months |  |
U.S. Treasury and Government Agencies [Member] |  |  |  |  |  |
Assets Measured at Fair Value on Recurring Basis [Abstract] |  |  |  |  |  |
Available-for-sale securities, debt securities | 242,799 | 210,572 |  | $ 242,799 |  | 210,572
State and Political Subdivisions [Member] |  |  |  |  |  |
Assets Measured at Fair Value on Recurring Basis [Abstract] |  |  |  |  |  |
Available-for-sale securities, debt securities | 123,992 | 145,015 |  | 123,992 |  | 145,015
U.S. Government Sponsored Agency Mortgage-backed Securities [Member] |  |  |  |  |  |
Assets Measured at Fair Value on Recurring Basis [Abstract] |  |  |  |  |  |
Available-for-sale securities, debt securities | 201,911 | 205,309 |  | 201,911 |  | 205,309
Other Debt Securities [Member] |  |  |  |  |  |
Assets Measured at Fair Value on Recurring Basis [Abstract] |  |  |  |  |  |
Available-for-sale securities, debt securities | 506 | 507 |  | 506 |  | 507
Recurring [Member] |  |  |  |  |  |
Assets Measured at Fair Value on Recurring Basis [Abstract] |  |  |  |  |  |
Mortgage servicing rights | 3,815 | 3,484 |  | 3,815 |  | 3,484
Recurring [Member] | U.S. Treasury and Government Agencies [Member] |  |  |  |  |  |
Assets Measured at Fair Value on Recurring Basis [Abstract] |  |  |  |  |  |
Available-for-sale securities, debt securities | 242,799 | 210,572 |  | 242,799 |  | 210,572
Recurring [Member] | State and Political Subdivisions [Member] |  |  |  |  |  |
Assets Measured at Fair Value on Recurring Basis [Abstract] |  |  |  |  |  |
Available-for-sale securities, debt securities | 123,992 | 145,015 |  | 123,992 |  | 145,015
Recurring [Member] | U.S. Government Sponsored Agency Mortgage-backed Securities [Member] |  |  |  |  |  |
Assets Measured at Fair Value on Recurring Basis [Abstract] |  |  |  |  |  |
Available-for-sale securities, debt securities | 201,911 | 205,309 |  | 201,911 |  | 205,309
Recurring [Member] | Other Debt Securities [Member] |  |  |  |  |  |
Assets Measured at Fair Value on Recurring Basis [Abstract] |  |  |  |  |  |
Available-for-sale securities, debt securities | 506 | 507 |  | 506 |  | 507
Recurring [Member] | CRA Investments Funds [Member] |  |  |  |  |  |
Assets Measured at Fair Value on Recurring Basis [Abstract] |  |  |  |  |  |
Available for sale securities, equity securities |  | 24,358 |  |  |  | 24,358
Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] |  |  |  |  |  |
Assets Measured at Fair Value on Recurring Basis [Abstract] |  |  |  |  |  |
Mortgage servicing rights | 0 | 0 |  | 0 |  | 0
Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | U.S. Treasury and Government Agencies [Member] |  |  |  |  |  |
Assets Measured at Fair Value on Recurring Basis [Abstract] |  |  |  |  |  |
Available-for-sale securities, debt securities | 91,465 | 64,598 |  | 91,465 |  | 64,598
Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | State and Political Subdivisions [Member] |  |  |  |  |  |
Assets Measured at Fair Value on Recurring Basis [Abstract] |  |  |  |  |  |
Available-for-sale securities, debt securities | 0 | 0 |  | 0 |  | 0
Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | U.S. Government Sponsored Agency Mortgage-backed Securities [Member] |  |  |  |  |  |
Assets Measured at Fair Value on Recurring Basis [Abstract] |  |  |  |  |  |
Available-for-sale securities, debt securities | 0 | 0 |  | 0 |  | 0
Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Other Debt Securities [Member] |  |  |  |  |  |
Assets Measured at Fair Value on Recurring Basis [Abstract] |  |  |  |  |  |
Available-for-sale securities, debt securities | 0 | 0 |  | 0 |  | 0
Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | CRA Investments Funds [Member] |  |  |  |  |  |
Assets Measured at Fair Value on Recurring Basis [Abstract] |  |  |  |  |  |
Available for sale securities, equity securities |  | 24,358 |  |  |  | 24,358
Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] |  |  |  |  |  |
Assets Measured at Fair Value on Recurring Basis [Abstract] |  |  |  |  |  |
Mortgage servicing rights | 0 | 0 |  | 0 |  | 0
Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | U.S. Treasury and Government Agencies [Member] |  |  |  |  |  |
Assets Measured at Fair Value on Recurring Basis [Abstract] |  |  |  |  |  |
Available-for-sale securities, debt securities | 151,334 | 145,974 |  | 151,334 |  | 145,974
Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | State and Political Subdivisions [Member] |  |  |  |  |  |
Assets Measured at Fair Value on Recurring Basis [Abstract] |  |  |  |  |  |
Available-for-sale securities, debt securities | 123,992 | 145,015 |  | 123,992 |  | 145,015
Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | U.S. Government Sponsored Agency Mortgage-backed Securities [Member] |  |  |  |  |  |
Assets Measured at Fair Value on Recurring Basis [Abstract] |  |  |  |  |  |
Available-for-sale securities, debt securities | 201,911 | 205,309 |  | 201,911 |  | 205,309
Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Other Debt Securities [Member] |  |  |  |  |  |
Assets Measured at Fair Value on Recurring Basis [Abstract] |  |  |  |  |  |
Available-for-sale securities, debt securities | 506 | 507 |  | 506 |  | 507
Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | CRA Investments Funds [Member] |  |  |  |  |  |
Assets Measured at Fair Value on Recurring Basis [Abstract] |  |  |  |  |  |
Available for sale securities, equity securities |  | 0 |  |  |  | 0
Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] |  |  |  |  |  |
Assets Measured at Fair Value on Recurring Basis [Abstract] |  |  |  |  |  |
Mortgage servicing rights | 3,815 | 3,484 |  | 3,815 |  | 3,484
Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | U.S. Treasury and Government Agencies [Member] |  |  |  |  |  |
Assets Measured at Fair Value on Recurring Basis [Abstract] |  |  |  |  |  |
Available-for-sale securities, debt securities | 0 | 0 |  | 0 |  | 0
Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | State and Political Subdivisions [Member] |  |  |  |  |  |
Assets Measured at Fair Value on Recurring Basis [Abstract] |  |  |  |  |  |
Available-for-sale securities, debt securities | 0 | 0 |  | 0 |  | 0
Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | U.S. Government Sponsored Agency Mortgage-backed Securities [Member] |  |  |  |  |  |
Assets Measured at Fair Value on Recurring Basis [Abstract] |  |  |  |  |  |
Available-for-sale securities, debt securities | 0 | 0 |  | 0 |  | 0
Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Other Debt Securities [Member] |  |  |  |  |  |
Assets Measured at Fair Value on Recurring Basis [Abstract] |  |  |  |  |  |
Available-for-sale securities, debt securities | 0 | 0 |  | 0 |  | 0
Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | CRA Investments Funds [Member] |  |  |  |  |  |
Assets Measured at Fair Value on Recurring Basis [Abstract] |  |  |  |  |  |
Available for sale securities, equity securities |  | 0 |  |  |  | 0
Recurring [Member] | Mortgage Servicing Rights [Member] |  |  |  |  |  |
Reconciliation of beginning and ending balances of recurring fair value measurements recognized in balance sheet using significant unobservable (Level 3) inputs [Roll Forward] |  |  |  |  |  |
Beginning balance | 3,772 | 3,283 | 3,304 | 3,484 | 3,433 | 3,433
Total recognized gains (losses) Included in net income | 45 |  | 5 | 341 | (73) |
Issues | 118 |  | 98 | 329 | 269 |
Settlements | (120) |  | (124) | (339) | (346) |
Ending balance | 3,815 | 3,484 | 3,283 | 3,815 | 3,283 | 3,484
Total gains (losses) for the period included in net income attributable to the change in unrealized gains or losses related to assets still held at the reporting date | 45 |  | 5 | 341 | (73) |
Nonrecurring [Member] |  |  |  |  |  |
Impaired loan (collateral dependent) [Abstract] |  |  |  |  |  |
Impaired loans, fair value adjustments | 100 | 300 | 300 | 200 | 700 | 1,000
Other real estate owned [Abstract] |  |  |  |  |  |
Other real estate owned, fair value adjustment | 800 | 200 | $ 900 | 1,800 | $ 2,600 | 2,500
Nonrecurring [Member] | Fair Value [Member] |  |  |  |  |  |
Assets measured-nonrecurring basis [Abstract] |  |  |  |  |  |
Impaired loans (collateral dependent) | 556 | 2,709 |  | 556 |  | 2,709
Other real estate owned | 7,640 | 18,951 |  | 7,640 |  | 18,951
Nonrecurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Fair Value [Member] |  |  |  |  |  |
Assets measured-nonrecurring basis [Abstract] |  |  |  |  |  |
Impaired loans (collateral dependent) | 0 | 0 |  | 0 |  | 0
Other real estate owned | 0 | 0 |  | 0 |  | 0
Nonrecurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Fair Value [Member] |  |  |  |  |  |
Assets measured-nonrecurring basis [Abstract] |  |  |  |  |  |
Impaired loans (collateral dependent) | 0 | 0 |  | 0 |  | 0
Other real estate owned | 0 | 0 |  | 0 |  | 0
Nonrecurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Fair Value [Member] |  |  |  |  |  |
Assets measured-nonrecurring basis [Abstract] |  |  |  |  |  |
Impaired loans (collateral dependent) | 556 | 2,709 |  | 556 |  | 2,709
Other real estate owned | $ 7,640 | $ 18,951 |  | $ 7,640 |  | $ 18,951

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- Definition This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents mortgage servicing right at fair value. + References No definition available. + Details
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- Definition This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents other real estate owned at fair value. + References No definition available. + Details
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- Definition Amount of unrealized (holding) gain (loss) which is included in the statement of income (or changes in net assets) related to those assets still held at the reporting date for which fair value is measured on a recurring basis using significant unobservable inputs (Level 3). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=99377789&loc=d3e19207-110258 + Details
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