Computation of Earnings Per Common Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Jul. 27, 2013	Apr. 27, 2013	Jan. 26, 2013	Oct. 27, 2012	Jul. 28, 2012	Apr. 28, 2012	Jan. 28, 2012	Oct. 29, 2011	Jul. 27, 2013	Jul. 28, 2012	Jul. 30, 2011
Basic earnings per unit
Net income	$ 14,666	$ 7,199	$ 1,463	$ 11,861	$ 13,282	$ 9,645	$ 3,485	$ 12,966	$ 35,188	$ 39,378	$ 16,107
Weighted-average number of common shares (in shares)									33,012,595	33,653,055	35,306,900
Basic earnings per common share	$ 0.44	$ 0.22	$ 0.04	$ 0.36	$ 0.40	$ 0.29	$ 0.10	$ 0.39	$ 1.07	$ 1.17	$ 0.46
Diluted earnings per unit
Weighted-average number of common shares (in shares)									33,012,595	33,653,055	35,306,900
Potential common stock arising from stock options, and unvested restricted share units (in shares)									769,592	828,840	447,268
Total shares-diluted (in shares)									33,782,187	34,481,895	35,754,168
Diluted earnings per common share	$ 0.43	$ 0.21	$ 0.04	$ 0.35	$ 0.39	$ 0.28	$ 0.10	$ 0.38	$ 1.04	$ 1.14	$ 0.45
Anti-dilutive weighted shares excluded from the calculation of earnings per share (in shares)									1,204,116	1,262,964	2,071,254