Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Assets:
Debt securities available-for-sale at amortized cost	$ 1,362,748	$ 1,430,605
Shareholders' equity:
Preferred stock, shares authorized (in shares)	300,000	300,000
Common stock, par value (in dollars per share)	$ 5	$ 5
Common stock, shares authorized (in shares)	25,000,000	25,000,000
Common stock, shares issued (in shares)	17,983,700	17,918,280
Common stock, shares outstanding (in shares)	17,983,700	17,918,280