Consolidated Statements Of Changes In Shareholders' Equity - USD ($)	Total	Common Stock Outstanding [Member]	Common Stock [Member]	Additional Paid-In Capital [Member]	Accumulated Other Comprehensive Income (Loss), Net of Deferred Income Taxes [Member]	Retained Earnings [Member]	Retained Earnings [Member] Cumulative Effect Period Of Adoption Adjustment [Member]	Treasury Stock [Member]
Balance at Dec. 31, 2018			$ 692,000	$ 2,188,777,000	$ (462,557,000)	$ 9,531,433,000		$ (3,397,548,000)
Balance (Accounting Standards Update 2016-13 [Member]) at Dec. 31, 2018							$ 0
Balance, shares at Dec. 31, 2018		40,651,148
Issued during the period, net, shares		194,584
Treasury shares acquired, shares		(75,193)
Issued during the period, net			2,000
Share-based compensation plans				767,000
Net increase (decrease) during the period					246,446,000
Net income (loss)						354,551,000
Dividends declared ($1.55 per share in 2020 and $1.40 per share in 2019)						(57,137,000)
Purchase of treasury shares								(16,153,000)
Balance at Mar. 31, 2019			694,000	2,189,544,000	(216,111,000)	9,828,847,000		(3,413,701,000)
Balance, shares at Mar. 31, 2019		40,770,539
Balance at Dec. 31, 2018			692,000	2,188,777,000	(462,557,000)	9,531,433,000		(3,397,548,000)
Balance (Accounting Standards Update 2016-13 [Member]) at Dec. 31, 2018							0
Balance, shares at Dec. 31, 2018		40,651,148
Net increase (decrease) during the period	$ 508,828,000
Net income (loss)	791,817,000
Dividends declared ($1.55 per share in 2020 and $1.40 per share in 2019)	(171,131,000)
Balance at Sep. 30, 2019	8,983,258,000		694,000	2,206,326,000	46,272,000	10,152,118,000		(3,422,152,000)
Balance, shares at Sep. 30, 2019		40,780,469
Balance at Mar. 31, 2019			694,000	2,189,544,000	(216,111,000)	9,828,847,000		(3,413,701,000)
Balance, shares at Mar. 31, 2019		40,770,539
Issued during the period, net, shares		9,403
Treasury shares acquired, shares		(39,440)
Issued during the period, net
Share-based compensation plans				8,917,000
Net increase (decrease) during the period					171,209,000
Net income (loss)						332,868,000
Dividends declared ($1.55 per share in 2020 and $1.40 per share in 2019)						(56,999,000)
Purchase of treasury shares								(8,451,000)
Balance at Jun. 30, 2019			694,000	2,198,461,000	(44,902,000)	10,104,716,000		(3,422,152,000)
Balance, shares at Jun. 30, 2019		40,740,502
Issued during the period, net, shares		39,967
Treasury shares acquired, shares
Issued during the period, net
Share-based compensation plans				7,865,000
Net increase (decrease) during the period	91,173,000				91,174,000
Net income (loss)	104,398,000					104,398,000
Dividends declared ($1.55 per share in 2020 and $1.40 per share in 2019)	(56,995,000)					(56,995,000)
Purchase of treasury shares
Balance at Sep. 30, 2019	8,983,258,000		694,000	2,206,326,000	46,272,000	10,152,118,000		(3,422,152,000)
Balance, shares at Sep. 30, 2019		40,780,469
Balance at Dec. 31, 2019	$ 9,132,925,000		694,000	2,219,660,000	28,152,000	10,306,571,000		(3,422,152,000)
Balance (Accounting Standards Update 2016-13 [Member]) at Dec. 31, 2019							(4,214,000)
Balance, shares at Dec. 31, 2019	69,464,000	40,798,963
Issued during the period, net, shares		159,423
Treasury shares acquired, shares		(970,892)
Issued during the period, net			2,000
Share-based compensation plans				(3,181,000)
Net increase (decrease) during the period					(297,903,000)
Net income (loss)						16,612,000
Dividends declared ($1.55 per share in 2020 and $1.40 per share in 2019)						(63,277,000)
Purchase of treasury shares								(200,020,000)
Balance at Mar. 31, 2020			696,000	2,216,479,000	(269,751,000)	10,255,692,000		(3,622,172,000)
Balance, shares at Mar. 31, 2020		39,987,494
Balance at Dec. 31, 2019	$ 9,132,925,000		694,000	2,219,660,000	28,152,000	10,306,571,000		(3,422,152,000)
Balance (Accounting Standards Update 2016-13 [Member]) at Dec. 31, 2019							$ (4,214,000)
Balance, shares at Dec. 31, 2019	69,464,000	40,798,963
Net increase (decrease) during the period	$ 383,446,000
Net income (loss)	450,549,000
Dividends declared ($1.55 per share in 2020 and $1.40 per share in 2019)	(187,115,000)
Balance at Sep. 30, 2020	$ 9,591,292,000		696,000	2,235,378,000	411,598,000	10,565,792,000		(3,622,172,000)
Balance, shares at Sep. 30, 2020	69,603,000	39,966,516
Balance at Mar. 31, 2020			696,000	2,216,479,000	(269,751,000)	10,255,692,000		(3,622,172,000)
Balance, shares at Mar. 31, 2020		39,987,494
Issued during the period, net, shares		(15,849)
Treasury shares acquired, shares
Issued during the period, net
Share-based compensation plans				9,514,000
Net increase (decrease) during the period					566,888,000
Net income (loss)						190,880,000
Dividends declared ($1.55 per share in 2020 and $1.40 per share in 2019)						(61,927,000)
Purchase of treasury shares
Balance at Jun. 30, 2020			696,000	2,225,993,000	297,137,000	10,384,645,000		(3,622,172,000)
Balance, shares at Jun. 30, 2020		39,971,645
Issued during the period, net, shares		(5,129)
Treasury shares acquired, shares
Issued during the period, net
Share-based compensation plans				9,385,000
Net increase (decrease) during the period	$ 114,461,000				114,461,000
Net income (loss)	243,057,000					243,057,000
Dividends declared ($1.55 per share in 2020 and $1.40 per share in 2019)	(61,910,000)					(61,910,000)
Purchase of treasury shares
Balance at Sep. 30, 2020	$ 9,591,292,000		$ 696,000	$ 2,235,378,000	$ 411,598,000	$ 10,565,792,000		$ (3,622,172,000)
Balance, shares at Sep. 30, 2020	69,603,000	39,966,516