CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY AND COMPREHENSIVE INCOME (USD $) In Thousands, unless otherwise specified	Total	Common Stock and Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Earnings (Loss)
Balance at beginning of period at Dec. 31, 2009	$ 1,203,749	$ 389,316	$ 807,303	$ 7,130
Balance (in shares) at beginning of period at Dec. 31, 2009		152,826
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings for the year	248,126		248,126
Income tax benefit of common stock options exercised	8,263	8,263
Repurchase of common stock (in shares)		(1,306)
Repurchase of common stock	(35,725)	(35,725)
Common stock issued pursuant to stock-based compensation plans, net (in shares)		2,397
Common stock issued pursuant to stock-based compensation plans, net	17,388	17,388
Stock-based compensation expense	25,352	25,352
Conversion of convertible debt (in shares)		5,295
Conversion of convertible debt	58,752	58,752
Stock issued for acquisitions	2,121	2,121
Change in minimum liability for pension plans, net of tax effects	664			664
Translation adjustment	(6,142)			(6,142)
Balance at end of period at Dec. 31, 2010	1,522,548	465,467	1,055,429	1,652
Balance (in shares) at end of period at Dec. 31, 2010		159,212
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings for the year	221,474		221,474
Income tax benefit of common stock options exercised	5,545	5,545
Repurchase of common stock (in shares)		(6,135)
Repurchase of common stock	(160,669)	(160,669)
Common stock issued pursuant to stock-based compensation plans, net (in shares)		1,892
Common stock issued pursuant to stock-based compensation plans, net	16,751	16,751
Stock-based compensation expense	25,063	25,063
Stock issued for acquisitions	0
Dividends paid	(38,037)		(38,037)
Change in minimum liability for pension plans, net of tax effects	(1,113)			(1,113)
Translation adjustment	(12,533)			(12,533)
Balance at end of period at Dec. 31, 2011	1,579,029	352,157	1,238,866	(11,994)
Balance (in shares) at end of period at Dec. 31, 2011		154,969
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings for the year	222,398		222,398
Income tax benefit of common stock options exercised	39	39
Repurchase of common stock (in shares)		(10,466)
Repurchase of common stock	(214,195)	(214,195)
Common stock issued pursuant to stock-based compensation plans, net (in shares)		1,311
Common stock issued pursuant to stock-based compensation plans, net	7,644	7,644
Stock-based compensation expense	25,901	25,901
Stock issued for acquisitions	0
Dividends paid	(42,450)		(42,450)
Change in minimum liability for pension plans, net of tax effects	745			745
Translation adjustment	20,790			20,790
Balance at end of period at Dec. 31, 2012	$ 1,599,901	$ 171,546	$ 1,418,814	$ 9,541
Balance (in shares) at end of period at Dec. 31, 2012		145,814