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
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
Retained earnings					$ 1,497,757