Condensed Statements of Changes in Shareholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Common Stock [Member]	Capital In Excess Of Par Value [Member]	Retained Earnings [Member]
Balance at Dec. 31, 2019		$ 11,953	$ 218,462	$ 2,850,302
Share repurchases		(223)		(306,568)
Cash dividends declared				(35,877)
Share-based compensation and share issuances		7	4,275
Taxes paid in exchange for shares withheld		(2)	(2,731)
Forward contract for accelerated share repurchases			(37,500)
Cash paid for fractional shares		(1)	(611)
Net income				280,982
Balance at Jun. 30, 2020	$ 2,982,468	11,734	181,895	2,788,839
Balance at Mar. 31, 2020		11,813	217,187	2,787,049
Share repurchases		(80)		(128,417)
Cash dividends declared				(17,598)
Share-based compensation and share issuances		1	2,208
Forward contract for accelerated share repurchases			(37,500)
Net income				147,805
Balance at Jun. 30, 2020	2,982,468	11,734	181,895	2,788,839
Balance at Dec. 31, 2020	3,326,288	11,706	226,451	3,088,131
Share repurchases		(129)		(280,086)
Cash dividends declared				(46,387)
Share-based compensation and share issuances		6	7,042
Taxes paid in exchange for shares withheld		(2)	(4,539)
Forward contract for accelerated share repurchases			(68,750)
Net income				468,935
Balance at Jun. 30, 2021	3,402,378	11,581	160,204	3,230,593
Balance at Mar. 31, 2021		11,596	156,126	3,024,195
Share repurchases		(16)		(39,984)
Cash dividends declared				(23,194)
Share-based compensation and share issuances		1	4,078
Net income				269,576
Balance at Jun. 30, 2021	$ 3,402,378	$ 11,581	$ 160,204	$ 3,230,593