Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Assets:
Debt securities available-for-sale at amortized cost	$ 1,486,869	$ 1,461,829
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)	17,901,373	17,843,081
Common stock, shares outstanding (in shares)	17,901,373	17,843,081