Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Investment securities:
Securities held to maturity, fair value (in dollars)	$ 1,920,941	$ 2,084,736
Shareholders' equity:
Common stock, par value (in dollars per share)	$ 2.50	$ 2.50
Common stock, shares authorized	160,000,000	160,000,000
Common stock, shares issued	76,195,723	76,022,039
Common stock, shares outstanding	76,195,723	76,022,039