CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Retained Earnings [Member] Cumulative Effect, Period of Adoption, Adjustment	Treasury Stock [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
Beginning Balances at Jul. 31, 2018	$ 700,140	$ 548	$ 325,631	$ 553,454		$ (71,120)	$ (56,401)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	131,258
Other Comprehensive Income (Loss), Net of Tax	(14,853)						(14,853)
Issuance of shares of Class A Common Stock under stock plan			(7,963)			(27,970)
Tax benefit and withholdings from deferred compensation distributions			209
Stock-based compensation expense (Note 7)			12,092
Repurchase of shares of Class A Common Stock						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	752,112	548	329,969	637,843		(46,332)	(71,254)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Adoption of ASU 2014-09 "Revenue from Contracts with Customers" (Note 9)					$ (2,137)
Net income	112,369
Other Comprehensive Income (Loss), Net of Tax	4,777						4,777
Issuance of shares of Class A Common Stock under stock plan			(7,184)			(3,630)
Tax benefit and withholdings from deferred compensation distributions			134
Stock-based compensation expense (Note 7)			8,843
Repurchase of shares of Class A Common Stock						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)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	129,659
Other Comprehensive Income (Loss), Net of Tax	10,524						10,524
Issuance of shares of Class A Common Stock under stock plan			(2,767)			(1,748)
Tax benefit and withholdings from deferred compensation distributions			32
Stock-based compensation expense (Note 7)			10,098
Repurchase of shares of Class A Common Stock	(3,593)
Payment of Ordinary Dividends, Common Stock Class A				(42,690)
Payment of Ordinary Dividends, Common Stock Class B				(3,056)
Ending Balances at Jul. 31, 2021	$ 963,028	$ 548	$ 339,125	$ 788,369		$ (109,061)	$ (55,953)