Components of Equity (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance			$ 1,994,373	$ 1,847,213
Cumulative effect of accounting change	$ (22,462)		(22,462)
Exercise of stock options and release of restricted awards, net of shares withheld for employee taxes			133,060	134,014
Issuance of shares under stock purchase plan			33,292	28,767
Shares repurchased under provisions of stock repurchase plans			(555,760)	(340,736)
Stock compensation expense			43,171	39,036
Net earnings	163,067	$ 120,606	440,213	322,928
Other comprehensive (loss) income	(10,929)	7,489	(28,129)	25,585
Dividends paid			79,180	75,726
Purchase of noncontrolling interest			(613)
Distributions to noncontrolling interest			(633)
Ending Balance	1,957,332	1,981,081	1,957,332	1,981,081
Shareholders' Equity
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance			1,991,858	1,844,638
Cumulative effect of accounting change	(22,357)		(22,357)
Exercise of stock options and release of restricted awards, net of shares withheld for employee taxes			133,060	134,014
Issuance of shares under stock purchase plan			33,292	28,767
Shares repurchased under provisions of stock repurchase plans			(555,760)	(340,736)
Stock compensation expense			43,171	39,036
Net earnings			438,989	322,378
Other comprehensive (loss) income			(27,135)	25,632
Dividends paid			79,180	75,726
Purchase of noncontrolling interest			(89)
Distributions to noncontrolling interest			0
Ending Balance	1,955,849	1,978,003	1,955,849	1,978,003
Noncontrolling Interest
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance			2,515	2,575
Cumulative effect of accounting change	(105)		(105)
Net earnings			1,224	550
Other comprehensive (loss) income			(994)	(47)
Purchase of noncontrolling interest			(524)
Distributions to noncontrolling interest			(633)
Ending Balance	$ 1,483	$ 3,078	$ 1,483	$ 3,078