Consolidated Statements Of Equity - USD ($) $ in Thousands	Common Stock [Member]	Capital In Excess Of Par Value [Member]	Retained Earnings [Member]	Treasury Stock [Member]	Total
Balance at Dec. 31, 2020	$ 124,285	$ 3,379,057	$ 1,261,862	$ (81,327)	$ 4,683,877
Net income			183,689		183,689
Dividends declared and paid			(61,520)		(61,520)
Issuance of common stock from private placement	49	4,112			4,161
Repurchase of stock				(3,262)	(3,262)
Equity compensation plan	97	(97)
Exercise of stock options	10	704			714
Stock-based compensation		2,631	(174)		2,457
Other		(31)		256	225
Balance at Mar. 31, 2021	124,441	3,386,376	1,383,857	(84,333)	4,810,341
Balance at Dec. 31, 2020	124,285	3,379,057	1,261,862	(81,327)	4,683,877
Net income					264,603
Balance at Jun. 30, 2021	124,500	3,393,372	1,403,041	(84,098)	4,836,815
Balance at Mar. 31, 2021	124,441	3,386,376	1,383,857	(84,333)	4,810,341
Net income			80,914		80,914
Other comprehensive income, net of income tax of $73			(61,584)		(61,584)
Issuance of common stock under dividend reinvestment plan	46	4,049			4,095
Repurchase of stock				(17)	(17)
Equity compensation plan	2	(2)
Exercise of stock options	11	781			792
Stock-based compensation		2,316	(146)		2,170
Other		(148)		252	104
Balance at Jun. 30, 2021	124,500	3,393,372	1,403,041	(84,098)	4,836,815
Retained earnings					1,434,201
Balance at Dec. 31, 2021	128,050	3,705,814	1,434,201	(83,615)	5,184,450
Net income			199,376		199,376
Dividends declared and paid			(67,821)		(67,821)
Dividends declared			(67,863)		(67,863)
Issuance of common stock under dividend reinvestment plan	47	4,070			4,117
Repurchase of stock				(1,012)	(1,012)
Equity compensation plan	29	(29)
Exercise of stock options	14	998			1,012
Stock-based compensation		2,716	(136)		2,580
Other		(9)		270	261
Balance at Mar. 31, 2022	128,140	3,713,560	1,497,757	(84,357)	5,255,100
Balance at Dec. 31, 2021	128,050	3,705,814	1,434,201	(83,615)	5,184,450
Net income					281,667
Balance at Jun. 30, 2022	132,707	3,715,975	1,577,442	(84,092)	5,342,032
Balance at Mar. 31, 2022	128,140	3,713,560	1,497,757	(84,357)	5,255,100
Net income			82,291		82,291
Dividends declared and paid			(2,424)		(2,424)
Issuance of common stock from stock purchase contracts	4,515	(4,515)
Issuance of common stock under dividend reinvestment plan	47	4,007			4,054
Repurchase of stock				(15)	(15)
Equity compensation plan	2	(2)
Exercise of stock options	3	224			227
Stock-based compensation		2,725	(182)		2,543
Other		(24)		280	256
Balance at Jun. 30, 2022	$ 132,707	$ 3,715,975	$ 1,577,442	$ (84,092)	5,342,032
Retained earnings					$ 1,577,442