Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Surplus	Accumulated Other Comprehensive Income (Loss)	Undivided Profits
Beginning balance at Dec. 31, 2022	$ 3,269,362	$ 1,270	$ 2,530,066	$ (517,560)	$ 1,255,586
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive (loss) income	124,330			(26,820)	151,150
Stock issued for employee stock purchase plan	833		833
Stock-based compensation plans, net	6,955	4	6,951
Stock repurchases	(39,999)	(23)	(39,976)
Dividends on common stock	(75,926)				(75,926)
Ending balance at Sep. 30, 2023	3,285,555	1,251	2,497,874	(544,380)	1,330,810
Beginning balance at Jun. 30, 2023	3,356,326	1,262	2,516,398	(469,988)	1,308,654
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive (loss) income	(27,145)			(74,392)	47,247
Stock-based compensation plans, net	1,442	1	1,441
Stock repurchases	(19,977)	(12)	(19,965)
Dividends on common stock	(25,091)				(25,091)
Ending balance at Sep. 30, 2023	3,285,555	1,251	2,497,874	(544,380)	1,330,810
Beginning balance at Dec. 31, 2023	3,426,488	1,252	2,499,930	(404,375)	1,329,681
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive (loss) income	172,888			68,514	104,374
Stock issued for employee stock purchase plan	970		970
Stock-based compensation plans, net	7,542	4	7,538
Dividends on common stock	(79,055)				(79,055)
Ending balance at Sep. 30, 2024	3,528,833	1,256	2,508,438	(335,861)	1,355,000
Beginning balance at Jun. 30, 2024	3,458,869	1,255	2,506,469	(405,481)	1,356,626
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive (loss) income	94,360			69,620	24,740
Stock-based compensation plans, net	1,970	1	1,969
Dividends on common stock	(26,366)				(26,366)
Ending balance at Sep. 30, 2024	$ 3,528,833	$ 1,256	$ 2,508,438	$ (335,861)	$ 1,355,000