Acquisitions - Summary of Consideration Paid and Fair Value of Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Thousands	Apr. 01, 2019	Dec. 31, 2019	Sep. 30, 2019	Dec. 31, 2018	Dec. 31, 2017
Consideration Paid:
Issuance of common stock (in shares)	2,361,686
Liabilities assumed:
Goodwill resulting from merger with HomeTown		$ 84,002		$ 43,872	$ 43,872
HomeTown Bankshares Corporation Merger
Consideration Paid:
Cash paid in lieu of fractional shares	$ 27
Value of consideration	83,250
Assets acquired:
Cash and cash equivalents	26,283
Investment securities	34,876
Restricted stock	2,588
Loans	444,324
Premises and equipment	12,554
Deferred income taxes	2,960
Core deposit intangible	8,200
Other real estate owned	1,442
Banked owned life insurance	8,246
Other assets	14,244
Total assets	555,717
Liabilities assumed:
Deposits	483,626
Short-term FHLB advances	14,883
Long-term FHLB advances	778
Subordinated debt	7,530
Other liabilities	5,780
Total liabilities	512,597
Net assets acquired	43,120
Goodwill resulting from merger with HomeTown	40,130	$ 40,130	$ 40,761
Common Stock | HomeTown Bankshares Corporation Merger
Consideration Paid:
Issuance of common shares, replacement options, and restricted stock	82,470
Issuance of replacement stock options/restricted stock | HomeTown Bankshares Corporation Merger
Consideration Paid:
Issuance of common shares, replacement options, and restricted stock	$ 753