Consolidated Statements of Changes in Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock [Member]	Capital Surplus [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss), Net [Member]
Balance at Dec. 31, 2021	$ 3,670,352	$ 309,513	$ 1,755,701	$ 1,659,073	$ (53,935)
Balance, Shares Issued at Dec. 31, 2021		92,947
Net income	524,089			524,089
Other comprehensive income (loss)	(718,247)				(718,247)
Comprehensive income (loss)	(194,158)
Cash dividends declared	(94,891)			(94,891)
Common stock activity, long-term incentive plans	16,640		16,498	142
Issuance of stock from dividend reinvestment and stock purchase plans	3,577		3,577
Repurchase of common stock	(58,892)		(58,892)
Balance at Dec. 31, 2022	3,342,628	$ 309,513	1,716,884	2,088,413	(772,182)
Balance, Shares Issued at Dec. 31, 2022		92,947
Net income	392,602			392,602
Other comprehensive income (loss)	151,055				151,055
Comprehensive income (loss)	543,657
Cash dividends declared	(105,557)			(105,557)
Common stock activity, long-term incentive plans	19,118		18,972	146
Issuance of stock from dividend reinvestment and stock purchase plans	3,815		3,815
Balance at Dec. 31, 2023	$ 3,803,661	$ 309,513	1,739,671	2,375,604	(621,127)
Balance, Shares Issued at Dec. 31, 2023	92,947	92,947
Net income	$ 460,815			460,815
Other comprehensive income (loss)	15,035				15,035
Comprehensive income (loss)	475,850
Cash dividends declared	(131,946)			(131,946)
Common stock activity, long-term incentive plans	13,780		13,647	133
Issuance of stock from dividend reinvestment and stock purchase plans	4,120		4,120
Repurchase of common stock	(37,829)		(37,829)
Balance at Dec. 31, 2024	$ 4,127,636	$ 309,513	$ 1,719,609	$ 2,704,606	$ (606,092)
Balance, Shares Issued at Dec. 31, 2024	92,947	92,947