Stockholders' Equity - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jan. 31, 2020	Jan. 31, 2019	Jan. 31, 2020	Jan. 31, 2019	Jul. 31, 2019	Oct. 31, 2018	Jul. 31, 2018
Schedule Of Stockholders Equity [Line Items]
Accumulated other comprehensive loss	$ (72,490)		$ (72,490)		$ (71,254)		$ (56,401)
Beginning balance	876,535	$ 772,943	850,774	$ 752,112
Net income	33,553	29,227	71,051	59,864
Other comprehensive loss, net of tax	(1,207)	5,666	(1,236)	(4,164)
Issuance of shares of Class A Common Stock under stock plan			(3,046)	(15,137)
Tax benefit and withholdings from deferred compensation distributions			133
Adjustments to Additional Paid in Capital, Income Tax Deficiency from Share-based Compensation				209
Stock-based compensation expense			5,384	7,805
Purchase of shares of Class A Common Stock				(3,182)
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets						$ (2,137)
Cash dividends on Class A common stock			(21,655)	(20,818)
Cash dividends on Class B common stock			(1,481)	(1,445)
Ending balance	899,924	803,381	899,924	803,381
Common Stock
Schedule Of Stockholders Equity [Line Items]
Beginning balance	548	548	548	548
Ending balance	548	548	548	548
Additional Paid-in Capital
Schedule Of Stockholders Equity [Line Items]
Beginning balance	327,241	326,182	329,969	325,631
Issuance of shares of Class A Common Stock under stock plan			(6,223)	(4,667)
Tax benefit and withholdings from deferred compensation distributions		118	133	209
Stock-based compensation expense			5,384	7,805
Ending balance	329,263	328,978	329,263	328,978
Retained Earnings
Schedule Of Stockholders Equity [Line Items]
Beginning balance	663,808	570,858	637,843	553,454
Net income			71,051	59,864
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets						$ (2,137)
Cash dividends on Class A common stock			(21,655)	(20,818)
Cash dividends on Class B common stock			(1,481)	(1,445)
Ending balance	685,758	588,918	685,758	588,918
Treasury Stock
Schedule Of Stockholders Equity [Line Items]
Beginning balance	(43,779)	(58,414)	(46,332)	(71,120)
Issuance of shares of Class A Common Stock under stock plan			(3,177)	(19,804)
Adjustments to Additional Paid in Capital, Income Tax Deficiency from Share-based Compensation				0
Purchase of shares of Class A Common Stock		1,319		(3,182)
Ending balance	(43,155)	(54,498)	(43,155)	(54,498)
Accumulated Other Comprehensive Loss
Schedule Of Stockholders Equity [Line Items]
Accumulated other comprehensive loss		(60,565)		(60,565)
Beginning balance	(71,283)	(66,231)	(71,254)
Other comprehensive loss, net of tax			(1,236)	(4,164)
Ending balance	$ (72,490)	$ (60,565)	$ (72,490)	$ (60,565)