Unaudited Condensed Consolidated Statements of Changes in Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Paid-in Capital	Retained Earnings- Substantially Restricted	Accumulated Other Compre- hensive (Loss) Income
Balance, beginning (in shares) at Dec. 31, 2021		110,687,533
Balance, beginning at Dec. 31, 2021	$ 3,177,622	$ 1,107	$ 2,338,814	$ 810,342	$ 27,359
Increase (Decrease) in Stockholders' Equity
Net income	67,795			67,795
Other comprehensive loss	(275,168)				(275,168)
Cash dividends declared	(36,648)			(36,648)
Stock issuances under stock incentive plans	0	$ 1	(1)
Stock issuances under stock incentive plans (in shares)		75,783
Stock-based compensation and related taxes	592		592
Balance, ending (in shares) at Mar. 31, 2022		110,763,316
Balance, ending at Mar. 31, 2022	$ 2,934,193	$ 1,108	2,339,405	841,489	(247,809)
Balance, beginning (in shares) at Dec. 31, 2022	110,777,780	110,777,780
Balance, beginning at Dec. 31, 2022	$ 2,843,305	$ 1,108	2,344,005	966,984	(468,792)
Increase (Decrease) in Stockholders' Equity
Net income	61,211			61,211
Other comprehensive loss	58,564				58,564
Cash dividends declared	(36,686)			(36,686)
Stock issuances under stock incentive plans	0	$ 1	(1)
Stock issuances under stock incentive plans (in shares)		90,933
Stock-based compensation and related taxes	$ 510		510
Balance, ending (in shares) at Mar. 31, 2023	110,868,713	110,868,713
Balance, ending at Mar. 31, 2023	$ 2,926,904	$ 1,109	$ 2,344,514	$ 991,509	$ (410,228)