Fair Value Measurements - Additional Quantitative Information (Details)	Mar. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Impaired loans	$ 50,478,000	$ 50,182,000
Non-recurring basis
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Impaired loans	10,001,000	10,999,000
OREO	84,000	55,000
Bank property held for sale	1,832,000	1,832,000
Non-recurring basis | Level 3
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Impaired loans	10,001,000	10,999,000
OREO	84,000	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 Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Impaired loans	10,001,000	10,999,000
Non-recurring basis | Level 3 | Appraisal of collateral | OREO
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
OREO	84,000	55,000
Non-recurring basis | Level 3 | Appraisal of collateral or real estate listing price | Bank property held for sale
Fair Value Measurements, Recurring and Nonrecurring, 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 Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Impaired loans	(4.1)	(3.3)
Appraisal adjustments | Non-recurring basis | Level 3 | Appraisal of collateral | Impaired loans | Maximum
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Impaired loans	(100.0)	(100.0)
Appraisal adjustments | Non-recurring basis | Level 3 | Appraisal of collateral | OREO | Minimum
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
OREO	(25.0)	(25.0)
Appraisal adjustments | Non-recurring basis | Level 3 | Appraisal of collateral | OREO | Maximum
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
OREO	100.0	(100.0)
Appraisal adjustments | Non-recurring basis | Level 3 | Appraisal of collateral or real estate listing price | Bank property held for sale | Minimum
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Bank property held for sale		$ 0.0
Bank property held for sale	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 Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Bank property held for sale		$ (35.1)
Bank property held for sale	(35.1)