Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Surplus	Accumulated Other Comprehensive Income (Loss)	Undivided Profits
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 income (loss)	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 income (loss)	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
Beginning balance at Dec. 31, 2024	3,528,872	1,257	2,511,590	(360,910)	1,376,935
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive income (loss)	(428,204)			47,427	(475,631)
Stock issued for employee stock purchase plan	836		836
Stock-based compensation plans, net	9,310	3	9,307
Issuance of common stock	327,431	187	327,244
Dividends on common stock	(84,282)				(84,282)
Ending balance at Sep. 30, 2025	3,353,963	1,447	2,848,977	(313,483)	817,022
Beginning balance at Jun. 30, 2025	3,549,210	1,260	2,518,286	(380,900)	1,410,564
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive income (loss)	(495,375)			67,417	(562,792)
Stock-based compensation plans, net	3,447	0	3,447
Issuance of common stock	327,431	187	327,244
Dividends on common stock	(30,750)				(30,750)
Ending balance at Sep. 30, 2025	$ 3,353,963	$ 1,447	$ 2,848,977	$ (313,483)	$ 817,022