CONSOLIDATED BALANCE SHEETS (Parentheticals) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Amortized cost of securities	$ 5,100,344	$ 6,788,729
Held to maturity, allowance for credit losses	0	0
Held to maturity, fair value	$ 838,241	$ 829,403
Common stock, par value (in dollars per share)	$ 1	$ 1
Common stock, shares authorized (in shares)	60,000,000	60,000,000
Common stock, shares issued (in shares)	42,688,008	42,467,394
Preferred Stock
Preferred stock, par value (in dollars per share)	$ 1	$ 1
Preferred stock, shares authorized (in shares)	188,500	6,104
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Series E preferred stock
Preferred stock, par value (in dollars per share)	$ 1	$ 1
Preferred stock, shares authorized (in shares)	11,500	11,500
Preferred stock, shares issued (in shares)	11,500	11,500
Preferred stock, shares outstanding (in shares)	11,500	11,500
Level 2
Held to maturity, fair value	$ 816,399	$ 776,557
Obligations of states and political subdivisions
Held to maturity, allowance for credit losses	0	0
Held to maturity, fair value	$ 838,241	$ 829,403