Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Statement Of Financial Position [Abstract]
Securities available for sale, amortized cost	$ 6,380,002	$ 6,984,530
Securities held to maturity, fair value	2,429,049	1,631,482
Loans held-for-sale, fair value	25,046	41,022
Property and equipment, accumulated depreciation	286,052	280,065
Right of use assets, accumulated amortization	$ 37,511	$ 34,425
Preferred stock, par value per share	$ 20.00	$ 20.00
Common stock, par value per share	$ 3.33	$ 3.33