Stockholders' Equity (Details) - USD ($) $ in Thousands	3 Months Ended
	Oct. 31, 2019	Oct. 31, 2018	Jul. 31, 2019	Jul. 31, 2018
Schedule Of Stockholders Equity [Line Items]
Additional paid-in capital	$ 327,241		$ 329,969
Retained earnings	663,808		637,843
Treasury Stock, Value	43,779		46,332
Accumulated other comprehensive loss	(71,283)		(71,254)	$ (56,401)
Treasury Stock, Value, Acquired, Cost Method		$ (1,863)
Stockholders' Equity Attributable to Parent	876,535	772,943	850,774	752,112
Net income	37,498	30,637
Other Comprehensive Income (Loss), Net of Tax	(29)	(9,830)
Issuance of shares of Class A Common Stock under plan	(3,857)	(10,064)
Adjustments to Additional Paid in Capital, Income Tax Benefit from Share-based Compensation	(64)	(91)
Share-based Compensation	3,618	4,965
Stock Repurchased During Period, Value	0
Cumulative Effect of New Accounting Principle in Period of Adoption		(2,137)
Payment of Ordinary Dividends, Common Stock Class A	(10,822)	(10,403)
Payment of Ordinary Dividends, Common Stock Class B	(711)	(693)
Common Stock [Member]
Schedule Of Stockholders Equity [Line Items]
Common Stock, Value, Issued	548	548	548	548
Additional Paid-in Capital [Member]
Schedule Of Stockholders Equity [Line Items]
Additional paid-in capital	327,241	326,182	329,969	325,631
Issuance of shares of Class A Common Stock under plan	(6,410)	(4,505)
Adjustments to Additional Paid in Capital, Income Tax Benefit from Share-based Compensation	(64)	(91)
Share-based Compensation	3,618	4,965
Retained Earnings [Member]
Schedule Of Stockholders Equity [Line Items]
Retained earnings	663,808	570,858	637,843	553,454
Net income		30,637
Cumulative Effect of New Accounting Principle in Period of Adoption		(2,137)
Payment of Ordinary Dividends, Common Stock Class A	(10,822)	(10,403)
Payment of Ordinary Dividends, Common Stock Class B	(711)	(693)
Treasury Stock [Member]
Schedule Of Stockholders Equity [Line Items]
Treasury Stock, Value	(43,779)	(58,414)	(46,332)	$ (71,120)
Treasury Stock, Value, Acquired, Cost Method		1,863
Issuance of shares of Class A Common Stock under plan	(2,553)	(14,569)
Stock Repurchased During Period, Value	0
AOCI Attributable to Parent [Member]
Schedule Of Stockholders Equity [Line Items]
Accumulated other comprehensive loss	(71,283)	(66,231)	$ (71,254)
Other Comprehensive Income (Loss), Net of Tax	$ (29)	$ (9,830)