Stockholders' Equity - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jan. 31, 2021	Jan. 31, 2020	Jan. 31, 2021	Jan. 31, 2020	Oct. 31, 2020	Jul. 31, 2020	Oct. 31, 2019	Jul. 31, 2019
Schedule Of Stockholders Equity [Line Items]
Stockholders' Equity Attributable to Parent	$ 919,335	$ 899,924	$ 919,335	$ 899,924	$ 880,401	$ 863,072	$ 876,535	$ 850,774
Net income	30,860	33,553	64,341	71,051
Other Comprehensive Income (Loss), Net of Tax	18,207	(1,207)	15,016	(1,236)
Issuance of shares of Class A Common Stock under stock plan	(289)	(811)	(2,167)	(3,046)
APIC, Share-based Payment Arrangement, Increase for Cost Recognition	1,897	1,766	5,471	5,384
Tax benefit and withholdings from deferred compensation distributions			32
Adjustments to Additional Paid in Capital, Income Tax Deficiency from Share-based Compensation		69		133
Treasury Stock, Value, Acquired, Cost Method	(873)		(3,593)
Payment of Ordinary Dividends, Common Stock Class A	(10,667)	(10,833)	(21,338)	(21,655)
Payment of Ordinary Dividends, Common Stock Class B	(779)	(770)	(1,499)	(1,481)
Common Stock [Member]
Schedule Of Stockholders Equity [Line Items]
Stockholders' Equity Attributable to Parent	548	548	548	548	548	548	548	548
Additional Paid-in Capital [Member]
Schedule Of Stockholders Equity [Line Items]
Stockholders' Equity Attributable to Parent	334,077	329,263	334,077	329,263	332,121	331,761	327,241	329,969
Stock Issued, Value, Stock Options Exercised and Restricted Stock Vested	(59)	(187)	(3,187)	(6,223)
APIC, Share-based Payment Arrangement, Increase for Cost Recognition	1,897	1,766	5,471	5,384
Tax benefit and withholdings from deferred compensation distributions		69	32	133
Retained Earnings [Member]
Schedule Of Stockholders Equity [Line Items]
Stockholders' Equity Attributable to Parent	745,960	685,758	745,960	685,758	726,546	704,456	663,808	637,843
Net income			64,341	71,051
Payment of Ordinary Dividends, Common Stock Class A	(10,667)	(10,833)	(21,338)	(21,655)
Payment of Ordinary Dividends, Common Stock Class B	(779)	(770)	(1,499)	(1,481)
Treasury Stock [Member]
Schedule Of Stockholders Equity [Line Items]
Stockholders' Equity Attributable to Parent	(109,789)	(43,155)	(109,789)	(43,155)	(109,146)	(107,216)	(43,779)	(46,332)
Stock Issued, Value, Stock Options Exercised and Restricted Stock Vested	(230)	(624)	(1,020)	(3,177)
Adjustments to Additional Paid in Capital, Income Tax Deficiency from Share-based Compensation				0
Treasury Stock, Value, Acquired, Cost Method	(873)		(3,593)
AOCI Attributable to Parent [Member]
Schedule Of Stockholders Equity [Line Items]
Stockholders' Equity Attributable to Parent	(51,461)	(72,490)	(51,461)	(72,490)	$ (69,668)	$ (66,477)	$ (71,283)	$ (71,254)
Other Comprehensive Income (Loss), Net of Tax	$ 18,207	$ (1,207)	$ 15,016	$ (1,236)