Consolidated Statements Of Shareholders' Equity (USD $) In Thousands, except Share data, unless otherwise specified	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Treasury Balance [Member]
Beginning Balance at Dec. 31, 2011	$ 2,420,256	$ 3,391	$ 968,392	$ 6,824,180	$ (476,733)	$ (4,898,974)
Beginning Balance, shares at Dec. 31, 2011		339,107,230
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	623,925			623,925
Total other comprehensive loss, net of tax (Note 10)	(130,945)				(130,945)
Dividends	(141,681)			(141,681)
Repurchase of common stock	(311,632)					(311,632)
Share-based compensation and 401(k) match made with Treasury shares	42,058		42,056			2
Issuance of nonvested stock (in shares)		535,807
Issuance of nonvested stock		6	(6)
Exercise of stock options	45,973	16	45,957
Exercise of stock options (in shares)		1,622,801
Tax benefit of stock options and nonvested stock	9,670		9,670
Ending Balance at Dec. 31, 2012	2,557,624	3,413	1,066,069	7,306,424	(607,678)	(5,210,604)
Ending Balance, shares at Dec. 31, 2012		341,265,838
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 at Dec. 31, 2013	3,009,486	3,432	1,175,052	7,852,729	(332,676)	(5,689,051)
Ending Balance, shares at Dec. 31, 2013		343,157,231
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)	1,002,000	1,001,531
Tax benefit of stock options and nonvested stock	11,582		11,582
Ending Balance at Dec. 31, 2014	$ 2,909,286	$ 3,442	$ 1,265,257	$ 8,459,040	$ (514,943)	$ (6,303,510)
Ending Balance, shares at Dec. 31, 2014		344,174,653