CONSOLIDATED BALANCE SHEETS (UNAUDITED) (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Available-for-sale [Abstract]
Securities AFS, at estimated fair value	$ 1,592,891	$ 2,655,594
Held-to-maturity Securities, Other Disclosure Items [Abstract]
Securities held-to-maturity, fair value	$ 943,322	$ 95,235
Shareholders' equity:
Common Stock, Par or Stated Value Per Share	$ 1.25	$ 1.25
Common stock, shares authorized (in shares)	80,000,000	80,000,000
Common stock, shares issued (in shares)	37,991,729	37,968,969
Treasury Stock, Shares	5,864,774	5,616,917