Consolidated Statements of Shareholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Loss	Treasury Balance
Beginning Balance, shares at Dec. 31, 2013		343,157,231
Balance, beginning of period 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 income (loss), net of tax	(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
Exercise of stock options (in shares)		1,001,531
Exercise of stock options	37,785	$ 10	37,775
Tax benefit of equity awards	11,582		11,582
Ending Balance, shares at Dec. 31, 2014		344,174,653
Balance, end of period 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 income (loss), net of tax	(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	0	$ 2	(2)
Exercise of stock options (in shares)		518,858
Exercise of stock options	20,179	$ 5	20,174
Tax benefit of equity awards	3,675		3,675
Ending Balance, shares at Dec. 31, 2015		344,855,704
Balance, end of period at Dec. 31, 2015	1,839,654	$ 3,449	1,328,561	8,961,985	(615,205)	(7,839,136)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	692,164			692,164
Total other comprehensive income (loss), net of tax	49,824				49,824
Dividends	(252,321)			(252,321)
Repurchase of common stock	(465,341)					(465,341)
Share-based compensation and 401(k) match made with Treasury shares	39,826		36,956			2,870
Issuance of nonvested stock (in shares)		272,479
Issuance of nonvested stock	$ 0	$ 2	(2)
Exercise of stock options (in shares)	468,000	466,871
Exercise of stock options	$ 15,782	$ 5	15,777
Tax benefit of equity awards	$ 570		570
Retirement of treasury stock (in shares)	(165,000,000)	(165,000,000)
Retirement of treasury stock	$ 0	$ (1,650)		(8,064,155)		8,065,805
Ending Balance, shares at Dec. 31, 2016		180,595,054
Balance, end of period at Dec. 31, 2016	$ 1,920,158	$ 1,806	$ 1,381,862	$ 1,337,673	$ (565,381)	$ (235,802)