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Fair Value - Financial Assets Accounted for at Fair Value (Details) | 3 Months Ended | 12 Months Ended |
--- | --- | --- | ---
Mar. 31, 2019 USD ($) | Mar. 31, 2018 USD ($) | Dec. 31, 2018 USD ($) | Dec. 31, 2017 USD ($)
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment | $ 0 |  | $ 27,000 |
Schedule of Company's financial instruments measured at fair values |  |  |  |
Total Fair value | 83,240,000 |  | 88,179,000 |
Real Estate Acquired Through Foreclosure Fair Value |  |  | 1,000 |
Real Estate Owned, Valuation Allowance, Valuation Increase | 0 | $ 25,000 |  |
Other real estate owned at carrying value before valuation allowance | 921,000 |  | 1,249,000 |
Real Estate Owned, Valuation Allowance | 0 | $ 321,000 | 23,000 | $ 305,000
Certificates of deposit [Member] |  |  |  |
Schedule of Company's financial instruments measured at fair values |  |  |  |
Total Fair value | 69,011,000 |  | 73,507,000 |
Equity Funds [Member] |  |  |  |
Schedule of Company's financial instruments measured at fair values |  |  |  |
Total Fair value | 0 |  | 0 |
Residential Mortgage Backed Securities [Member] |  |  |  |
Schedule of Company's financial instruments measured at fair values |  |  |  |
Total Fair value | 10,207,000 |  | 10,478,000 |
Debt Securities, Available-for-sale, Maturity, without Single Maturity Date, Fair Value | 10,207,000 |  |  |
Collateralized Debt Obligations [Member] |  |  |  |
Schedule of Company's financial instruments measured at fair values |  |  |  |
Total Fair value | 3,511,000 |  | 3,685,000 |
Debt Securities, Available-for-sale, Maturity, without Single Maturity Date, Fair Value | 3,511,000 |  |  |
Municipal Bonds [Member] |  |  |  |
Schedule of Company's financial instruments measured at fair values |  |  |  |
Total Fair value | 511,000 |  | 509,000 |
Nonrecurring [Member] |  |  |  |
Schedule of Company's financial instruments measured at fair values |  |  |  |
Total Fair value | 83,240,000 |  | 88,179,000 |
Nonrecurring [Member] | Certificates of deposit [Member] |  |  |  |
Schedule of Company's financial instruments measured at fair values |  |  |  |
Total Fair value | 69,011,000 |  | 73,507,000 |
Nonrecurring [Member] | Mortgage-backed securities - residential [Member] |  |  |  |
Schedule of Company's financial instruments measured at fair values |  |  |  |
Total Fair value | 10,207,000 |  | 10,478,000 |
Nonrecurring [Member] | Collateralized mortgage obligations - residential [Member] |  |  |  |
Schedule of Company's financial instruments measured at fair values |  |  |  |
Total Fair value | 3,511,000 |  | 3,685,000 |
Nonrecurring [Member] | Municipal Securities [Member] |  |  |  |
Schedule of Company's financial instruments measured at fair values |  |  |  |
Total Fair value | 511,000 |  | 509,000 |
Nonrecurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] |  |  |  |
Schedule of Company's financial instruments measured at fair values |  |  |  |
Total Fair value | 0 |  | 0 |
Nonrecurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Certificates of deposit [Member] |  |  |  |
Schedule of Company's financial instruments measured at fair values |  |  |  |
Total Fair value | 0 |  | 0 |
Nonrecurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Mortgage-backed securities - residential [Member] |  |  |  |
Schedule of Company's financial instruments measured at fair values |  |  |  |
Total Fair value | 0 |  | 0 |
Nonrecurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Collateralized mortgage obligations - residential [Member] |  |  |  |
Schedule of Company's financial instruments measured at fair values |  |  |  |
Total Fair value | 0 |  | 0 |
Nonrecurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Municipal Securities [Member] |  |  |  |
Schedule of Company's financial instruments measured at fair values |  |  |  |
Total Fair value | 0 |  | 0 |
Nonrecurring [Member] | Significant Observable Inputs (Level 2) [Member] |  |  |  |
Schedule of Company's financial instruments measured at fair values |  |  |  |
Total Fair value | 83,240,000 |  | 88,179,000 |
Nonrecurring [Member] | Significant Observable Inputs (Level 2) [Member] | Certificates of deposit [Member] |  |  |  |
Schedule of Company's financial instruments measured at fair values |  |  |  |
Total Fair value | 69,011,000 |  |  |
Nonrecurring [Member] | Significant Observable Inputs (Level 2) [Member] | Mortgage-backed securities - residential [Member] |  |  |  |
Schedule of Company's financial instruments measured at fair values |  |  |  |
Debt Securities, Available-for-sale, Maturity, without Single Maturity Date, Fair Value | 10,207,000 |  |  |
Nonrecurring [Member] | Significant Observable Inputs (Level 2) [Member] | Collateralized mortgage obligations - residential [Member] |  |  |  |
Schedule of Company's financial instruments measured at fair values |  |  |  |
Debt Securities, Available-for-sale, Maturity, without Single Maturity Date, Fair Value | 3,511,000 |  |  |
Nonrecurring [Member] | Significant Unobservable Inputs (Level 3) [Member] |  |  |  |
Schedule of Company's financial instruments measured at fair values |  |  |  |
Total Fair value | 0 |  | 0 |
Nonrecurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Certificates of deposit [Member] |  |  |  |
Schedule of Company's financial instruments measured at fair values |  |  |  |
Total Fair value | 0 |  | 0 |
Nonrecurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Mortgage-backed securities - residential [Member] |  |  |  |
Schedule of Company's financial instruments measured at fair values |  |  |  |
Total Fair value | 0 |  | 0 |
Nonrecurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Collateralized mortgage obligations - residential [Member] |  |  |  |
Schedule of Company's financial instruments measured at fair values |  |  |  |
Total Fair value | 0 |  | 0 |
Nonrecurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Municipal Securities [Member] |  |  |  |
Schedule of Company's financial instruments measured at fair values |  |  |  |
Total Fair value | 0 |  | 0 |
Commercial Real Estate [Member] |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment | $ 0 |  | 27,000 |
Impaired Financing Receivable, with Related Allowance, Recorded Investment |  |  | 270,000 |
Land Loans [Member] |  |  |  |
Schedule of Company's financial instruments measured at fair values |  |  |  |
Real Estate Acquired Through Foreclosure Fair Value |  |  | 1,000 |
Land Loans [Member] | Nonrecurring [Member] |  |  |  |
Schedule of Company's financial instruments measured at fair values |  |  |  |
Real Estate Acquired Through Foreclosure Fair Value |  |  | 1,000 |
Land Loans [Member] | Nonrecurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] |  |  |  |
Schedule of Company's financial instruments measured at fair values |  |  |  |
Real Estate Acquired Through Foreclosure Fair Value |  |  | 0 |
Land Loans [Member] | Nonrecurring [Member] | Significant Observable Inputs (Level 2) [Member] |  |  |  |
Schedule of Company's financial instruments measured at fair values |  |  |  |
Real Estate Acquired Through Foreclosure Fair Value |  |  | 0 |
Land Loans [Member] | Nonrecurring [Member] | Significant Unobservable Inputs (Level 3) [Member] |  |  |  |
Schedule of Company's financial instruments measured at fair values |  |  |  |
Real Estate Acquired Through Foreclosure Fair Value |  |  | $ 1,000 |
Sales Comparison Valuation Technique [Member] | Land Loans [Member] |  |  |  |
Schedule of Company's financial instruments measured at fair values |  |  |  |
Fair Value Measurements, Valuation Processes, Description |  |  | Sales comparison |
Fair Value Measurements, Sensitivity Analysis, Description |  |  | Discount applied to valuation |
Real estate owned, measurement input | 0.123 |  |  |
Measurement Input, Comparability Adjustment [Member] | Maximum [Member] | Real Estate Properties [Domain] | Nonresidential Real Estate [Member] |  |  |  |
Schedule of Company's financial instruments measured at fair values |  |  |  |
Real estate owned, measurement input |  |  | 0.1522 |
Measurement Input, Comparability Adjustment [Member] | Weighted Average [Member] | Real Estate Properties [Domain] | Nonresidential Real Estate [Member] |  |  |  |
Schedule of Company's financial instruments measured at fair values |  |  |  |
Real estate owned, measurement input |  |  | 0.1100 |
Land [Member] |  |  |  |
Schedule of Company's financial instruments measured at fair values |  |  |  |
Other real estate owned at carrying value before valuation allowance | $ 0 |  | $ 24,000 |
Real Estate Owned, Valuation Allowance | $ 0 |  | $ 23,000 |

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- Definition Description of the sensitivity of the fair value measurements to changes in unobservable inputs and the inter-relationships between those inputs as well as how those inter-relationships might magnify or mitigate the effect of changes in the unobservable inputs on the fair value measurements. + 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 (g) -URI http://asc.fasb.org/extlink&oid=99377789&loc=d3e19207-110258 + Details
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