CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Common Stock [Member]	Additional Paid-In Capital [Member]	Accumulated Other Comprehensive Loss [Member]	Retained Earnings [Member]	Total
Balance at Aug. 01, 2014	$ 238	$ 39,969	$ (4,733)	$ 493,167	$ 528,641
Balance (in shares) at Aug. 01, 2014	23,821,227
Comprehensive Income:
Net income	$ 0	0	0	163,903	163,903
Other comprehensive income, net of tax	0	0	1,008	0	1,008
Comprehensive income	0	0	1,008	163,903	164,911
Cash dividends declared	0	0	0	(171,383)	(171,383)
Share-based compensation	0	16,210	0	0	16,210
Issuance of share-based compensation awards, net of shares withheld for employee taxes	$ 2	(4,818)	0	0	(4,816)
Issuance of share-based compensation awards, net of shares withheld for employee taxes (in shares)	154,528
Tax benefit realized upon exercise of share-based compensation awards	$ 0	4,705	0	0	4,705
Purchases and retirement of common stock	$ 0	0	0	0	$ 0
Purchases and retirement of common stock (in shares)	0				0
Balance at Jul. 31, 2015	$ 240	56,066	(3,725)	485,687	$ 538,268
Balance (in shares) at Jul. 31, 2015	23,975,755
Comprehensive Income:
Net income	$ 0	0	0	189,299	189,299
Other comprehensive income, net of tax	0	0	(10,015)	0	(10,015)
Comprehensive income	0	0	(10,015)	189,299	179,284
Cash dividends declared	0	0	0	(186,505)	(186,505)
Share-based compensation	0	13,202	0	0	13,202
Issuance of share-based compensation awards, net of shares withheld for employee taxes	$ 1	(5,780)	0	0	(5,779)
Issuance of share-based compensation awards, net of shares withheld for employee taxes (in shares)	80,379
Tax benefit realized upon exercise of share-based compensation awards	$ 0	2,626	0	0	2,626
Purchases and retirement of common stock	$ (1)	(14,652)	0	0	$ (14,653)
Purchases and retirement of common stock (in shares)	(100,000)				(100,000)
Balance at Jul. 29, 2016	$ 240	51,462	(13,740)	488,481	$ 526,443
Balance (in shares) at Jul. 29, 2016	23,956,134				23,956,134
Comprehensive Income:
Net income	$ 0	0	0	201,899	$ 201,899
Other comprehensive income, net of tax	0	0	9,511	0	9,511
Comprehensive income	0	0	9,511	201,899	211,410
Cash dividends declared	0	0	0	(197,544)	(197,544)
Share-based compensation	0	8,458	0	0	8,458
Issuance of share-based compensation awards, net of shares withheld for employee taxes	$ 1	(6,897)	0	0	$ (6,896)
Issuance of share-based compensation awards, net of shares withheld for employee taxes (in shares)	99,548				99,548
Tax benefit realized upon exercise of share-based compensation awards	$ 0	2,636	0	0	$ 2,636
Purchases and retirement of common stock	$ 0	0	0	0	$ 0
Purchases and retirement of common stock (in shares)	0				0
Balance at Jul. 28, 2017	$ 241	$ 55,659	$ (4,229)	$ 492,836	$ 544,507
Balance (in shares) at Jul. 28, 2017	24,055,682				24,055,682