Components of Equity (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	$ 1,994,373	$ 1,847,213
Cumulative effect of accounting change	(22,462)
Exercise of stock options	26,397	45,365
Shares repurchased under provisions of stock repurchase plans	(172,360)	(53,908)
Stock compensation expense	11,267	10,623
Net earnings	136,200	93,567
Other comprehensive income (loss)	8,851	8,860
Ending Balance	1,982,266	1,951,720
Shareholders' Equity
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	1,991,858	1,844,638
Cumulative effect of accounting change	(22,357)
Exercise of stock options	26,397	45,365
Shares repurchased under provisions of stock repurchase plans	(172,360)	(53,908)
Stock compensation expense	11,267	10,623
Net earnings	135,692	93,264
Other comprehensive income (loss)	8,972	8,914
Ending Balance	1,979,469	1,948,896
Noncontrolling Interest
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	2,515	2,575
Cumulative effect of accounting change	(105)
Net earnings	508	303
Other comprehensive income (loss)	(121)	(54)
Ending Balance	$ 2,797	$ 2,824