Consolidated Statements of Equity and Comprehensive Income (USD $) In Thousands, except Share data, unless otherwise specified	Total	Common Stock	Additional paid-in capital	Retained earnings	Accumulated other comprehensive income (loss)	Total shareholders' equity	Noncontrolling interest
Beginning Balance at Dec. 31, 2008	$ 1,383,916	$ 2,120	$ 7,150	$ 1,372,356	$ (15,208)	$ 1,366,418	$ 17,498
Beginning Balance (in shares) at Dec. 31, 2008		211,973,377
Increase (Decrease) in Equity [Roll Forward]
Exercise of stock options and release of restricted shares (in shares)		2,068,603
Exercise of stock options and release of restricted shares	26,413	20	26,393	0	0	26,413
Issuance of shares under stock purchase plan		714,799
Issuance of shares under stock purchase plan (in shares)	20,512	7	20,505	0	0	20,512
Shares repurchased under provisions of stock repurchase plans (in shares)		(2,731,285)
Shares repurchased under provisions of stock repurchase plans	(84,509)	(27)	(84,482)	0	0	(84,509)
Stock compensation expense	39,135		39,135	0	0	39,135
Tax benefits from stock plans	5,726		5,726	0	0	5,726
Purchase of noncontrolling interest	(468)		3,838	0	0	3,838	(4,306)
Comprehensive income:
Net earnings	240,397			240,217		240,217	180
Foreign currency translation adjustments, net of tax	15,178				15,812	15,812	(634)
Total comprehensive Income	255,575					256,029	(454)
Dividends paid	(80,555)			(80,555)		(80,555)
Distributions or declaration of dividends to noncontrolling interest	(4,398)						(4,398)
Ending Balance at Dec. 31, 2009	1,561,347	2,120	18,265	1,532,018	604	1,553,007	8,340
Ending Balance (in shares) at Dec. 31, 2009		212,025,494
Increase (Decrease) in Equity [Roll Forward]
Exercise of stock options and release of restricted shares (in shares)		4,781,971
Exercise of stock options and release of restricted shares	79,234	48	79,186	0	0	79,234
Issuance of shares under stock purchase plan		694,329
Issuance of shares under stock purchase plan (in shares)	20,550	7	20,543	0	0	20,550
Shares repurchased under provisions of stock repurchase plans (in shares)		(5,454,020)
Shares repurchased under provisions of stock repurchase plans	(246,312)	(55)	(172,188)	(74,069)	0	(246,312)
Stock compensation expense	43,743		43,743	0	0	43,743
Tax benefits from stock plans	23,863		23,863	0	0	23,863
Comprehensive income:
Net earnings	344,205			344,172		344,172	33
Foreign currency translation adjustments, net of tax	7,447				7,521	7,521	(74)
Total comprehensive Income	351,652					351,693	(41)
Dividends paid	(84,872)			(84,872)		(84,872)
Distributions or declaration of dividends to noncontrolling interest	(1,051)						(1,051)
Ending Balance at Dec. 31, 2010	1,748,154	2,120	13,412	1,717,249	8,125	1,740,906	7,248
Ending Balance (in shares) at Dec. 31, 2010	212,047,774	212,047,774
Increase (Decrease) in Equity [Roll Forward]
Exercise of stock options and release of restricted shares (in shares)		1,632,077
Exercise of stock options and release of restricted shares	32,422	16	32,406	0	0	32,422
Issuance of shares under stock purchase plan		663,386
Issuance of shares under stock purchase plan (in shares)	24,224	7	24,217	0	0	24,224
Shares repurchased under provisions of stock repurchase plans (in shares)		(2,339,575)
Shares repurchased under provisions of stock repurchase plans	(112,071)	(23)	(106,353)	(5,695)	0	(112,071)
Stock compensation expense	44,278		44,278	0	0	44,278
Tax benefits from stock plans	5,300		5,300	0	0	5,300
Comprehensive income:
Net earnings	386,243			385,679		385,679	564
Foreign currency translation adjustments, net of tax	(12,131)				(11,705)	(11,705)	(426)
Reclassification adjustments for foreign currency realized losses, net of tax	616				616	616
Total comprehensive Income	374,728					374,590	138
Dividends paid	(106,011)			(106,011)		(106,011)
Distributions or declaration of dividends to noncontrolling interest	(955)						(955)
Ending Balance at Dec. 31, 2011	$ 2,010,069	$ 2,120	$ 13,260	$ 1,991,222	$ (2,964)	$ 2,003,638	$ 6,431
Ending Balance (in shares) at Dec. 31, 2011	212,003,662	212,003,662