Stockholders' Equity - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jan. 31, 2019	Jan. 31, 2018	Jan. 31, 2019	Jan. 31, 2018	Aug. 01, 2018
Schedule Of Stockholders Equity [Line Items]
Beginning balance	$ 772,943	$ 712,671	$ 752,112	$ 700,140
Net earnings	29,227	4,273	59,864	30,109
Other comprehensive loss, net of tax	5,666	16,973	(4,164)	9,592
Issuance of shares of Class A Common Stock under stock plan	(5,073)	(6,594)	(15,137)	(7,817)
Tax benefit and withholdings from deferred compensation distributions	118	45	209	(209)
Stock-based compensation expense	2,840	2,153	7,805	5,897
Purchase of shares of Class A Common Stock	(1,319)		(3,182)
Cumulative adjustment for ASU 2014-09, net of tax (Note B)					$ (2,137)
Cash dividends on Class A common stock	(10,415)	(10,004)	(20,818)	(19,967)
Cash dividends on Class B common stock	(752)	(731)	(1,445)	(1,406)
Ending balance	803,381	731,973	803,381	731,973
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	326,182	322,657	325,631	322,608
Issuance of shares of Class A Common Stock under stock plan	(162)	878	(4,667)	(2,985)
Tax benefit and withholdings from deferred compensation distributions	118	45	209	213
Stock-based compensation expense	2,840	2,153	7,805	5,897
Ending balance	328,978	325,733	328,978	325,733
Retained Earnings
Schedule Of Stockholders Equity [Line Items]
Beginning balance	570,858	522,334	553,454	507,136
Net earnings	29,227	4,273	59,864	30,109
Cumulative adjustment for ASU 2014-09, net of tax (Note B)					$ (2,137)
Cash dividends on Class A common stock	(10,415)	(10,004)	(20,818)	(19,967)
Cash dividends on Class B common stock	(752)	(731)	(1,445)	(1,406)
Ending balance	588,918	515,872	588,918	515,872
Treasury Stock
Schedule Of Stockholders Equity [Line Items]
Beginning balance	(58,414)	(80,806)	(71,120)	(85,470)
Issuance of shares of Class A Common Stock under stock plan	(5,235)	(5,716)	(19,804)	(10,802)
Tax benefit and withholdings from deferred compensation distributions				(422)
Purchase of shares of Class A Common Stock	1,319		3,182
Ending balance	(54,498)	(75,090)	(54,498)	(75,090)
Accumulated Other Comprehensive Loss
Schedule Of Stockholders Equity [Line Items]
Beginning balance	(66,231)	(52,062)	(56,401)	(44,682)
Other comprehensive loss, net of tax	5,666	16,972	(4,164)	9,592
Ending balance	$ (60,565)	$ (35,090)	$ (60,565)	$ (35,090)