CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Available-for-sale securities at fair value, amortized cost	$ 275,288	$ 258,104
Held-to-maturity securities at amortized cost, estimated fair value	13,737	14,480
Ending allowance balance for loans acquired with deteriorated credit quality	19,044	10,700
Bank premises and equipment, accumulated depreciation	$ 14,971	$ 12,432
Preferred stock, shares authorized (in shares)	5,000,000	5,000,000
Common stock, par value (in dollars per share)	$ 1.00	$ 1.00
Common stock, shares authorized (in shares)	40,000,000	40,000,000
Common stock, shares issued (in shares)	10,629,586	11,228,775
Common stock, shares outstanding (in shares)	10,629,586	11,228,775