Fair Value of Financial Instruments - Assets and Liabilities Measured at Fair Value Using Significant Unobservable Inputs (Level 3) (Details) $ in Thousands	Sep. 30, 2019 USD ($)	Dec. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)	Dec. 31, 2017 USD ($)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
OREO	$ 1,248	$ 1,505	$ 1,489	$ 3,792
Fair Value, Inputs, Level 3 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Impaired loans	3,661
OREO	1,248
Assets held-for-sale	$ 198
Fair Value, Inputs, Level 3 [Member] | Minimum [Member] | Measurement Input, Comparability Adjustment [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Impaired loans	0.09
OREO	0.09
Assets held-for-sale	0.09
Fair Value, Inputs, Level 3 [Member] | Maximum [Member] | Measurement Input, Comparability Adjustment [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Impaired loans	0.10
OREO	0.10
Assets held-for-sale	0.10
Fair Value, Inputs, Level 3 [Member] | Weighted Average [Member] | Measurement Input, Comparability Adjustment [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Impaired loans	(0.095)
OREO	(0.095)
Assets held-for-sale	(0.095)