Disclosures About Fair Value of Assets and Liabilities - Unobservable Inputs Used in Recurring and Nonrecurring Level 3 Fair Value Measurements Other Than Goodwill (Details) - Significant Unobservable Inputs (Level 3) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2018 USD ($)	Dec. 31, 2017 USD ($)
State and municipal securities | Discounted cash flow
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	$ 3,280	$ 3,943
State and municipal securities | Discounted cash flow | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Maturity/Call date	1 month	1 month
US Muni BQ curve	A-	A-
State and municipal securities | Discounted cash flow | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Maturity/Call date	20 years	20 years
US Muni BQ curve	BBB-	BBB-
Corporate obligations and U.S. Government-sponsored mortgage backed securities | Discounted cash flow
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	$ 35
Corporate obligations and equity securities | Discounted cash flow
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value		$ 35
Impaired loans (collateral dependent) | Collateral based measurements
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	5,344	9,576
Other real estate owned | Appraisals
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	$ 937	$ 859
Discount rate | State and municipal securities | Discounted cash flow | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Securities, Available-for-sale, Measurement Input	0.01	0.0069
Discount rate | State and municipal securities | Discounted cash flow | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Securities, Available-for-sale, Measurement Input	0.05	0.05
Risk free rate | Corporate obligations and U.S. Government-sponsored mortgage backed securities | Discounted cash flow
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Rate basis	3 month LIBOR
Risk free rate | Corporate obligations and equity securities | Discounted cash flow
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Rate basis		3 month LIBOR
Discount to reflect current market conditions | Corporate obligations and U.S. Government-sponsored mortgage backed securities | Discounted cash flow
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Securities, Available-for-sale, Measurement Input	0.0200
Discount to reflect current market conditions | Corporate obligations and equity securities | Discounted cash flow
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Securities, Available-for-sale, Measurement Input		0.0200
Discount to reflect current market conditions | Impaired loans (collateral dependent) | Collateral based measurements | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Securities, Available-for-sale, Measurement Input	0.00	0.00
Discount to reflect current market conditions | Impaired loans (collateral dependent) | Collateral based measurements | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Securities, Available-for-sale, Measurement Input	0.10	0.10
Discount to reflect current market conditions | Impaired loans (collateral dependent) | Collateral based measurements | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Securities, Available-for-sale, Measurement Input	0.02	0.01
Discount to reflect current market conditions | Other real estate owned | Appraisals | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Other real estate owned	0.00	0.00
Discount to reflect current market conditions | Other real estate owned | Appraisals | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Other real estate owned	0.24	0.10
Discount to reflect current market conditions | Other real estate owned | Appraisals | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Other real estate owned	0.03	0.02