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Fair Value (Additional Information) (Details) - USD ($) | 3 Months Ended | 12 Months Ended
--- | --- | ---
Mar. 31, 2019 | Dec. 31, 2018
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Loan held for sale, at fair value |  | $ 8,586,000 | $ 4,263,000
Contractual principal balance of loan held for sale |  | 8,420,000 | 4,231,000
Difference in amount of loan held for sale |  | 166,000 | 32,000
Impaired loans, carrying amount | [1] | 6,772,000 | 6,757,000
Valuation allowance for loans losses |  | 1,704,000 | 1,826,000
Other real estate carried at fair value less cost to sell |  | 0 | 0
Other real estate, adjustments to carrying value less costs to charged to earnings |  | 0 | 0
90 Days Past Due or Non-accrual |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Loan held for sale, at fair value |  | 0 | 0
Fair Value, Measurements, Recurring |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Securities |  | 824,597,000 | 812,611,000
Significant Unobservable Inputs (Level 3) | Fair Value, Measurements, Recurring |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Securities |  | 4,512,000 | 4,991,000
Obligations of State and Political Subdivisions | Fair Value, Measurements, Recurring |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Securities |  | 292,317,000 | 294,533,000
Obligations of State and Political Subdivisions | Significant Unobservable Inputs (Level 3) | Fair Value, Measurements, Recurring |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Securities |  | 4,512,000 | 4,991,000
Commercial Real Estate Loans |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Impaired loans, carrying amount |  | 5,494,000 | 6,561,000
Valuation allowance for loans losses |  | 1,426,000 | 1,823,000
Increase (decrease) to provision for loan losses |  | $ 397,000 | $ 411,000
[1] | Unpaid Principal Balance is the remaining contractual principal payments gross of partial charge-offs and discounts.

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- Definition Amount of other addition (reduction) in allowance reserve for credit loss. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 15 -URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5212-111524 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -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, after allowance for bad debt, of mortgage loan receivables held-for-sale that are not part of a disposal group. Excludes loans and leases covered under loss sharing agreements and loans classified as debt securities. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=82891408&loc=d3e4428-111522 + Details
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- Definition Carrying amount as of the balance sheet date of other real estate and foreclosed assets. Other real estate may include real estate investments, real estate loans that qualify as investments in real estate, and premises that are no longer used in operations may also be included in real estate owned. Foreclosed assets include all assets obtained in full or partial satisfaction of a debt arrangement through foreclosure proceedings. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03.10(4)) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 + Details
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