Consolidated Statements Of Shareholders' Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Treasury Balance [Member]
Beginning Balance, shares at Dec. 31, 2012		341,265,838
Beginning Balance at Dec. 31, 2012	$ 2,557,624	$ 3,413	$ 1,066,069	$ 7,306,424	$ (607,678)	$ (5,210,604)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	733,993			733,993
Total other comprehensive loss, net of tax (Note 10)	275,002				275,002
Dividends	(187,688)			(187,688)
Repurchase of common stock	(479,231)					(479,231)
Share-based compensation and 401(k) match made with Treasury shares	41,508		40,724			784
Issuance of nonvested stock (in shares)		492,755
Issuance of nonvested stock		$ (5)	(5)
Exercise of stock options	50,567	$ 14	50,553
Exercise of stock options (in shares)		1,398,638
Tax benefit of stock options and nonvested stock	17,711		17,711
Ending Balance, shares at Dec. 31, 2013		343,157,231
Ending Balance at Dec. 31, 2013	3,009,486	$ 3,432	1,175,052	7,852,729	(332,676)	(5,689,051)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	844,611			844,611
Total other comprehensive loss, net of tax (Note 10)	(182,267)				(182,267)
Dividends	(238,300)			(238,300)
Repurchase of common stock	(615,602)					(615,602)
Share-based compensation and 401(k) match made with Treasury shares	41,991		40,848			1,143
Issuance of nonvested stock (in shares)		15,891
Issuance of nonvested stock		$ 0	0
Exercise of stock options	37,785	$ 10	37,775
Exercise of stock options (in shares)		1,001,531
Tax benefit of stock options and nonvested stock	11,582		11,582
Ending Balance, shares at Dec. 31, 2014		344,174,653
Ending Balance at Dec. 31, 2014	2,909,286	$ 3,442	1,265,257	8,459,040	(514,943)	(6,303,510)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	752,207			752,207
Total other comprehensive loss, net of tax (Note 10)	(100,262)				(100,262)
Dividends	(249,262)			(249,262)
Repurchase of common stock	(1,537,020)					(1,537,020)
Share-based compensation and 401(k) match made with Treasury shares	40,851		39,457			1,394
Issuance of nonvested stock (in shares)		162,193
Issuance of nonvested stock		$ (2)	(2)
Exercise of stock options	$ 20,179	$ 5	20,174
Exercise of stock options (in shares)	517,000	518,858
Tax benefit of stock options and nonvested stock	$ 3,675		3,675
Ending Balance, shares at Dec. 31, 2015		344,855,704
Ending Balance at Dec. 31, 2015	$ 1,839,654	$ 3,449	$ 1,328,561	$ 8,961,985	$ (615,205)	$ (7,839,136)