Shareholders' Equity (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended		6 Months Ended
	Feb. 06, 2017	Jan. 27, 2017	Jan. 29, 2016	Jan. 27, 2017	Jan. 29, 2016
Shareholders' Equity [Abstract]
Number of shares issued from vesting of share-based compensation awards and stock option exercises (in shares)				86,439
Tax withholding payment net of cash received from issuance of share based compensation awards				$ 6,031	$ 5,343
Share-based compensation expense				4,011	$ 4,955
Excess tax benefit realized upon exercise of share-based compensation awards				$ 1,203
Dividends Payable [Line Items]
Cash dividends paid (in dollars per share)		$ 1.15	$ 1.10	$ 3.30	$ 5.20
Cash dividends declared (in dollars per share)		$ 1.15	$ 1.10	3.30	$ 2.20
Regular Quarterly Dividend Declared in Q2 [Member]
Dividends Payable [Line Items]
Cash dividends declared (in dollars per share)				$ 1.15
Dividend record date				Jan. 13, 2017
Regular Quarterly Dividend Declared in Q2 [Member] | Subsequent Event [Member]
Dividends Payable [Line Items]
Cash dividends paid (in dollars per share)	$ 1.15
Dividend payment date	Feb. 06, 2017