Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Statement of Financial Position [Abstract]
Allowance for credit losses - held to maturity securities	$ 32	$ 32
Securities held to maturity	$ 1,121,830	$ 1,206,540
Preferred stock, par value (usd per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized (in shares)	5,000,000	5,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (usd per share)	$ 5.00	$ 5.00
Common stock, shares authorized (in shares)	150,000,000	150,000,000
Common stock, shares issued (in shares)	59,296,725	59,296,725
Common stock, shares outstanding (in shares)	56,142,207	55,953,104
Treasury stock (in shares)	3,154,518	3,343,621