CONSOLIDATED STATEMENTS OF STOCKHOLDERS' INVESTMENT - USD ($) $ in Thousands	12 Months Ended
	Jul. 31, 2018	Jul. 31, 2017	Jul. 31, 2016
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common Stock, Value, Issued	$ 548	$ 548	$ 548
Beginning Balances	700,140
Net earnings	91,060	95,645	80,110
Other comprehensive loss, net of tax	(11,719)	10,063	(9,711)
Stock-based compensation expense	9,980	9,495	8,154
Stock Repurchased During Period, Value	(1,462)		(23,552)
Income Tax Effects Allocated Directly to Equity, Cumulative Effect of Change in Accounting Principle	1,869	0	0
Purchase of shares of Class A Common Stock	(1,462)	0	(23,552)
Ending Balances	752,112	700,140
Additional Paid-in Capital [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balances	322,608	317,001	314,403
Issuance of shares of Class A Common Stock under stock plan	(7,171)	(5,868)	(3,830)
Stockholder's equity, other		1,943	(10)
Tax benefit and withholdings from deferred compensation distributions	214	37	(1,716)
Stock-based compensation expense	9,980	9,495	8,154
Ending Balances	325,631	322,608	317,001
Retained Earnings [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balances	507,136	453,371	414,069
Net earnings	91,060	95,645	80,110
Income Tax Effects Allocated Directly to Equity, Cumulative Effect of Change in Accounting Principle	1,869
Payment of Ordinary Dividends, Common Stock Class A	(39,998)	(39,037)	(38,001)
Payment of Ordinary Dividends, Common Stock Class B	(2,875)	(2,843)	(2,807)
Ending Balances	553,454	507,136	453,371
Treasury Stock [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balances	(85,470)	(108,714)	(93,234)
Issuance of shares of Class A Common Stock under stock plan	16,234	23,591	8,300
Stockholder's equity, other	(422)	(347)	(228)
Ending Balances	(71,120)	(85,470)	(108,714)
Accumulated Other Comprehensive Income (Loss) [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balances	(44,682)	(54,745)	(45,034)
Other comprehensive loss, net of tax	(11,719)	10,063	(9,711)
Ending Balances	(56,401)	(44,682)	(54,745)
Other equity component [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balances	0	(3,863)	(3,064)
Stockholder's equity, other		3,863	(799)
Ending Balances	$ 0	$ 0	$ (3,863)