CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Statement Of Financial Position [Abstract]
Allowance for credit losses	$ 32,770	$ 33,619
Preferred stock, par value (in USD per share)	$ 5.00	$ 5.00
Preferred stock, shares authorized (in shares)	15,000,000	15,000,000
Preferred stock, shares issued (in shares)	0	0
Common stock, par value (in USD per share)	$ 1.00	$ 1.00
Common stock, shares authorized (in shares)	50,000,000	50,000,000
Common stock, shares issued (in shares)	14,069,858	12,951,676
Common stock, shares outstanding (in shares)	12,053,597	10,935,415
Treasury stock (in shares)	2,016,261	2,016,261