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]
Beginning Balances at Jul. 31, 2017	$ 700,140	$ 548	$ 322,608	$ 507,136	$ (85,470)	$ (44,682)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	91,060
Other comprehensive loss, net of tax	(11,719)					(11,719)
Stock Issued, Value, Stock Options Exercised and Restricted Stock Vested			(7,171)		(16,234)
Stockholder's equity, other					(422)
Tax benefit and withholdings from deferred compensation distributions			214
APIC, Share-based Payment Arrangement, Increase for Cost Recognition			9,980
Stock-based compensation expense	9,980
Stock Repurchased During Period, Value					1,462
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)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	131,258
Other comprehensive loss, net of tax	(14,853)					(14,853)
Stock Issued, Value, Stock Options Exercised and Restricted Stock Vested			(7,963)		(27,970)
Stockholder's equity, other					0
Tax benefit and withholdings from deferred compensation distributions			209
APIC, Share-based Payment Arrangement, Increase for Cost Recognition			12,092
Stock-based compensation expense	12,092
Stock Repurchased During Period, Value					3,182
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)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	112,369
Other comprehensive loss, net of tax	4,777					4,777
Stock Issued, Value, Stock Options Exercised and Restricted Stock Vested			(7,184)		(3,630)
Stockholder's equity, other					0
Tax benefit and withholdings from deferred compensation distributions			134
APIC, Share-based Payment Arrangement, Increase for Cost Recognition			8,843
Stock-based compensation expense	8,843
Stock Repurchased During Period, Value	(64,514)
Payment of Ordinary Dividends, Common Stock Class A				(42,736)
Payment of Ordinary Dividends, Common Stock Class B				(3,020)
Ending Balances at Jul. 31, 2020	$ 863,072	$ 548	$ 331,762	$ 704,456	$ (107,216)	$ (66,477)