Employee Benefit Plans - Narrative (Details)	12 Months Ended
	Dec. 31, 2019 USD ($) agreement	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined benefit plan with individual requisite age	21 years
Defined benefit plan with individual requisite service period	1 year
Accumulated benefit obligation	$ 6,262,000	$ 5,812,000	$ 8,313,000
Maximum percentage of limiting equities	5.00%
Employer matching contribution, service requirement	1 year
Employee benefits expense	$ 932,000	778,000	763,000
Period of deferred compensation agreements	10 years
Number of remaining agreements | agreement	1
Deferred compensation liability	$ 250,000	300,000
Deferred compensation arrangement expense	0	0	3,000
Profit sharing and incentive arrangements expense	1,217,000	1,643,000	1,108,000
Profit sharing and deferred compensation arrangements expense	158,000	141,000	$ 135,000
Minimum
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Deferred compensation arrangement annual payments	25,000
Maximum
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Deferred compensation arrangement annual payments	50,000
HomeTown Bankshares Corporation Merger
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Deferred compensation liability	$ 5,235,000	$ 3,412,000