Consolidated Balance Sheets (Parenthetical) - USD ($) shares in Thousands, $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Statement of Financial Position [Abstract]
Securities available for sale, amortized cost	$ 5,153,285	$ 4,031,494
Securities held to maturity	$ 18	$ 19
Preferred stock, par value	$ 1	$ 1
Preferred stock, shares authorized	50,000,000	50,000,000
Preferred stock, shares issued	0	0
Common stock, par value	$ 2.5	$ 2.5
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares issued	141,846,451	141,360,266
Common stock, shares in treasury	7,265,805	4,967,508
Allowance for credit losses on securities held for sale	$ 0	$ 0
Allowances for credit losses on securities held to maturity	1,020	1,020
Allowance for credit loss on accrued interest receivable	0	8
Mortgage servicing rights, net of valuation allowance	$ 0	$ 883