Fair Value Measurements - Additional Quantitative Information (Details) - USD ($)	Sep. 30, 2019	Dec. 31, 2018
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Impaired loans	$ 44,499,000	$ 50,182,000
Non-recurring basis
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Impaired loans	6,917,000	10,999,000
OREO	55,000	55,000
Bank property held for sale	1,832,000	1,832,000
Non-recurring basis | Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Impaired loans	6,917,000	10,999,000
OREO	55,000	55,000
Bank property held for sale	1,832,000	1,832,000
Non-recurring basis | Level 3 | Appraisal of collateral | Impaired loans
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Impaired loans	6,917,000	10,999,000
Non-recurring basis | Level 3 | Appraisal of collateral | OREO
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
OREO	55,000	55,000
Non-recurring basis | Level 3 | Appraisal of collateral or real estate listing price | Bank property held for sale
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Bank property held for sale	$ 1,832,000	$ 1,832,000
Appraisal adjustments | Non-recurring basis | Level 3 | Appraisal of collateral | Impaired loans | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Impaired loans (percent)	(5.6)	(3.3)
Appraisal adjustments | Non-recurring basis | Level 3 | Appraisal of collateral | Impaired loans | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Impaired loans (percent)	(100.0)	(100.0)
Appraisal adjustments | Non-recurring basis | Level 3 | Appraisal of collateral | Impaired loans | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Impaired loans		$ (24.1)
Impaired loans (percent)	(39.2)
Appraisal adjustments | Non-recurring basis | Level 3 | Appraisal of collateral | OREO | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
OREO (percent)	(25.0)	(25.0)
Appraisal adjustments | Non-recurring basis | Level 3 | Appraisal of collateral | OREO | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
OREO (percent)	(100.0)	(100.0)
Appraisal adjustments | Non-recurring basis | Level 3 | Appraisal of collateral | OREO | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
OREO (percent)	(65.0)	(65.0)
Appraisal adjustments | Non-recurring basis | Level 3 | Appraisal of collateral or real estate listing price | Bank property held for sale | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Bank property held for sale		$ 0.0
Bank property held for sale (percent)	0.0
Appraisal adjustments | Non-recurring basis | Level 3 | Appraisal of collateral or real estate listing price | Bank property held for sale | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Bank property held for sale		$ (35.1)
Bank property held for sale (percent)	(35.1)
Appraisal adjustments | Non-recurring basis | Level 3 | Appraisal of collateral or real estate listing price | Bank property held for sale | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Bank property held for sale (percent)	(28.3)	(28.3)