Stockholders' Equity - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Apr. 30, 2021	Apr. 30, 2020	Apr. 30, 2021	Apr. 30, 2020	Jan. 31, 2021	Jul. 31, 2020	Jan. 31, 2020	Jul. 31, 2019
Schedule Of Stockholders Equity [Line Items]
Stockholders' Equity Attributable to Parent	$ 951,626	$ 820,602	$ 951,626	$ 820,602	$ 919,335	$ 863,072	$ 899,924	$ 850,774
Net Income	37,291	13,633	101,632	84,684
Other Comprehensive Income (Loss), Net of Tax	2,913	(19,752)	17,929	(20,988)
Issuance of shares of Class A Common Stock under stock plan	(1,009)	(426)	(1,158)	(2,620)
Tax benefit and withholdings from deferred compensation distributions			32	133
Stock-based compensation expense	2,532	1,796	8,003	7,180
Repurchase of shares of Class A Common Stock		(64,113)	(3,593)	(64,113)
Payment of Ordinary Dividends, Common Stock Class A	(10,675)	(10,542)	(32,013)	(32,197)
Payment of Ordinary Dividends, Common Stock Class B	(779)	(770)	(2,278)	(2,251)
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	336,957	330,968	336,957	330,968	334,077	331,761	329,263	329,969
Issuance of shares of Class A Common Stock under stock plan	(348)	(91)	(2,839)	(6,314)
Tax benefit and withholdings from deferred compensation distributions			32	133
Stock-based compensation expense	2,532	1,796	8,003	7,180
Retained Earnings [Member]
Schedule Of Stockholders Equity [Line Items]
Stockholders' Equity Attributable to Parent	771,797	688,079	771,797	688,079	745,960	704,456	685,758	637,843
Net Income	37,291	13,633	101,632	84,684
Payment of Ordinary Dividends, Common Stock Class A	(10,675)	(10,542)	(32,013)	(32,197)
Payment of Ordinary Dividends, Common Stock Class B	(779)	(770)	(2,278)	(2,251)
Treasury Stock [Member]
Schedule Of Stockholders Equity [Line Items]
Stockholders' Equity Attributable to Parent	(109,128)	(106,751)	(109,128)	(106,751)	(109,789)	(107,216)	(43,155)	(46,332)
Issuance of shares of Class A Common Stock under stock plan	(661)	(517)	(1,681)	(3,694)
Repurchase of shares of Class A Common Stock		(64,113)	(3,593)	(64,113)
AOCI Attributable to Parent [Member]
Schedule Of Stockholders Equity [Line Items]
Stockholders' Equity Attributable to Parent	(48,548)	(92,242)	(48,548)	(92,242)	$ (51,461)	$ (66,477)	$ (72,490)	$ (71,254)
Other Comprehensive Income (Loss), Net of Tax	$ 2,913	$ (19,752)	$ 17,929	$ (20,988)