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]	Treasury Stock [Member]
Change to beginning balance due to adoption of Accounting Standards Update 2016-13						$ 0
Balance at Dec. 31, 2018			$ 692,000	$ 2,188,777,000	$ (462,557,000)	9,531,433,000	$ (3,397,548,000)
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, shares at Dec. 31, 2018		40,651,148
Net increase (decrease) during the period	$ 417,655,000
Net income (loss)	687,419,000
Dividends declared ($1.55 per share in 2020 and $1.40 per share in 2019)	(114,136,000)
Balance at Jun. 30, 2019	8,836,817,000		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
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				171,209,000
Net income (loss)	332,868,000					332,868,000
Dividends declared ($1.55 per share in 2020 and $1.40 per share in 2019)	(56,999,000)					(56,999,000)
Purchase of treasury shares							(8,451,000)
Balance at Jun. 30, 2019	8,836,817,000		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
Change to beginning balance due to adoption of Accounting Standards Update 2016-13						(4,214,000)
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, 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, shares at Dec. 31, 2019	69,464,000	40,798,963
Net increase (decrease) during the period	$ 268,984,000
Net income (loss)	207,492,000
Dividends declared ($1.55 per share in 2020 and $1.40 per share in 2019)	(125,205,000)
Balance at Jun. 30, 2020	$ 9,286,299,000		696,000	2,225,993,000	297,137,000	10,384,645,000	(3,622,172,000)
Balance, shares at Jun. 30, 2020	69,608,000	39,971,645
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				566,888,000
Net income (loss)	190,880,000					190,880,000
Dividends declared ($1.55 per share in 2020 and $1.40 per share in 2019)	(61,927,000)					(61,927,000)
Purchase of treasury shares
Balance at Jun. 30, 2020	$ 9,286,299,000		$ 696,000	$ 2,225,993,000	$ 297,137,000	$ 10,384,645,000	$ (3,622,172,000)
Balance, shares at Jun. 30, 2020	69,608,000	39,971,645