CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Cumulative Effect, Period of Adoption, Adjustment	Common Stock Class A Common Stock	Common Stock Class B Common Stock	Retained Earnings	Retained Earnings Cumulative Effect, Period of Adoption, Adjustment	Accumulated Other Comprehensive Loss	Treasury Stock
Balance (in shares) at Jul. 28, 2018			10,575	4,304				496
Balance at Jul. 28, 2018	$ 303,145		$ 61,678	$ 699	$ 258,104		$ (8,185)	$ (9,151)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	25,539				25,539
Other comprehensive income, net of tax	(157)				0		(157)
Dividends	$ (12,890)				(12,890)
Exercise of stock options (in shares)	(36)							(36)
Exercise of stock options	$ 1,007		$ 336					$ 671
Treasury stock purchases (in shares)								42
Treasury stock purchases	(1,070)							$ (1,070)
Restricted shares forfeited (in shares)			(15)
Restricted shares forfeited	(247)		$ (247)
Share-based compensation expense (in shares)			23
Share-based compensation expense	3,345		$ 3,345
Conversion of Class B shares to Class A shares (in shares)			10	10
Conversion of Class B shares to Class A shares	0		$ 2	$ (2)
Balance (in shares) at Jul. 27, 2019			10,593	4,294				502
Balance at Jul. 27, 2019	318,672	$ 3,514	$ 65,114	$ 697	270,753	$ 3,514	(8,342)	$ (9,550)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	24,939				24,939
Other comprehensive income, net of tax	(409)						(409)
Dividends	$ (12,965)				(12,965)
Exercise of stock options (in shares)	0
Treasury stock purchases (in shares)								224
Treasury stock purchases	$ (4,389)							$ (4,389)
Restricted shares forfeited (in shares)			(20)
Restricted shares forfeited	(208)		$ (208)
Share-based compensation expense (in shares)			412
Share-based compensation expense	3,166		$ 3,166
Balance (in shares) at Jul. 25, 2020			10,985	4,294				726
Balance at Jul. 25, 2020	$ 332,320		$ 68,072	$ 697	$ 286,241		$ (8,751)	$ (13,939)