CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Treasury Stock [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Other equity component [Member]
Beginning Balances at Jul. 31, 2016	$ 603,598	$ 548	$ 317,001	$ 453,371	$ (108,714)	$ (54,745)	$ (3,863)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	95,645
Other comprehensive loss, net of tax	10,063					10,063
Issuance of shares of Class A Common Stock under stock plan			(5,868)		23,591
Stockholder's equity, other			1,943		(347)		3,863
Tax benefit and withholdings from deferred compensation distributions			37
Stock-based compensation expense	9,495		9,495
Income Tax Effects Allocated Directly to Equity, Cumulative Effect of Change in Accounting Principle	0
Payment of Ordinary Dividends, Common Stock Class A				(39,037)
Payment of Ordinary Dividends, Common Stock Class B				(2,843)
Ending Balances at Jul. 31, 2017	700,140	548	322,608	507,136	(85,470)	(44,682)	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative Effect of New Accounting Principle in Period of Adoption				(1,869)
Net income	91,060
Other comprehensive loss, net of tax	(11,719)					(11,719)
Issuance of shares of Class A Common Stock under stock plan			(7,171)		16,234
Stockholder's equity, other					(422)
Tax benefit and withholdings from deferred compensation distributions			214
Stock-based compensation expense	9,980		9,980
Stock Repurchased During Period, Value					1,462
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)
Payment of Ordinary Dividends, Common Stock Class B				(2,875)
Ending Balances at Jul. 31, 2018	752,112	548	325,631	553,454	(71,120)	(56,401)	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	131,258
Other comprehensive loss, net of tax	(14,853)					(14,853)
Issuance of shares of Class A Common Stock under stock plan			(7,963)		27,970
Stockholder's equity, other					0
Tax benefit and withholdings from deferred compensation distributions			209
Stock-based compensation expense	12,092		12,092
Stock Repurchased During Period, Value	(3,182)
Income Tax Effects Allocated Directly to Equity, Cumulative Effect of Change in Accounting Principle	0			2,137
Payment of Ordinary Dividends, Common Stock Class A				(41,784)
Payment of Ordinary Dividends, Common Stock Class B				(2,948)
Ending Balances at Jul. 31, 2019	$ 850,774	$ 548	$ 329,969	$ 637,843	$ (46,332)	$ (71,254)	$ 0