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Troubled Debt Restructurings (Details Textual) | 3 Months Ended | 9 Months Ended | 12 Months Ended |
--- | --- | --- | --- | ---
Mar. 31, 2018 USD ($) Loans | Mar. 31, 2017 USD ($) Loans | Sep. 30, 2017 | Dec. 31, 2018 USD ($) | Dec. 31, 2017 USD ($)
Financing Receivable Modifications [Line Items] |  |  |  |  |
Total troubled debt restructurings | $ 5,300,000 |  |  |  | $ 5,000,000
Specific reserves to customers | 210,000 |  |  |  | 162,000
Commitments to lend additional amounts to borrowers classified as troubled debt restructurings | 0 |  |  |  | 0
Provision for loan losses | $ 775,000 | $ 1,050,000 |  |  |
Troubled debt restructured loans with subsequent payment defaults | Loans | Loans |  | 0 |  |  |
Residential real estate loan |  |  |  |  |
Financing Receivable Modifications [Line Items] |  |  |  |  |
Troubled debt restructured loans with subsequent payment defaults | Loans | Loans | 3 |  |  |  |
Loans default payment past due period | 30 days |  |  |  |
Residential Real Estate Loan And Home Equity Line Of Credit |  |  |  |  |
Financing Receivable Modifications [Line Items] |  |  |  |  |
Loans default payment past due period |  |  | 30 days |  |
Scenario, Forecast |  |  |  |  |
Financing Receivable Modifications [Line Items] |  |  |  |  |
Provision for loan losses |  |  |  | $ 0 |
Troubled debt restructurings |  |  |  |  |
Financing Receivable Modifications [Line Items] |  |  |  |  |
Specific reserves to customers | $ 75,000 |  |  |  | $ 68,000
Allowance adjustment charge offs | 19,000 | $ 13,000 |  |  |
Provision for loan losses | $ 19,000 | $ 13,000 |  |  |
Contractual Interest Rate Reduction |  |  |  |  |
Financing Receivable Modifications [Line Items] |  |  |  |  |
Reduction of the notes stated interest rate | 1.75% | 1.89% |  |  |
Extended Maturity |  |  |  |  |
Financing Receivable Modifications [Line Items] |  |  |  |  |
Maturity period loans | 6 months |  |  |  |
Extended Maturity | Minimum |  |  |  |  |
Financing Receivable Modifications [Line Items] |  |  |  |  |
Maturity period loans |  | 6 years |  |  |
Extended Maturity | Maximum |  |  |  |  |
Financing Receivable Modifications [Line Items] |  |  |  |  |
Maturity period loans |  | 132 months |  |  |

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- Definition Amount of valuation allowance for financing receivables that are expected to be uncollectible that were individually evaluated for impairment. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 11B -Subparagraph (g) -URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953423-111524 + Details
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