Shareholders' Equity (Narrative) (Details) (USD $) In Millions, except Share data, unless otherwise specified	0 Months Ended		6 Months Ended
	Jan. 27, 2012	Jan. 27, 2012	Jan. 31, 2012	Jan. 31, 2011	Nov. 18, 2011	Jul. 31, 2011	Mar. 26, 2010
Shareholders' Equity [Line Items]
Common stock authorized for repurchase							8,000,000
Stock repurchased during the period, shares			1,375,513
Stock repurchased during the period, value			$ 73.6
Average price per share			$ 53.48
Remaining authorization to repurchase under stock repurchase plan, shares			3,700,000
Common stock, par value			$ 5		$ 5.00	$ 5
Common stock, shares authorized			240,000,000			240,000,000
Cash dividend declared per common share		$ 0.16
Dividend payable, date of record	Feb. 17, 2012
Dividend payable, date to be paid				Mar. 09, 2012
Stock split declared in form of dividend, ratio		2
Percentage of stock split in form of dividend		100.00%
Minimum [Member]
Shareholders' Equity [Line Items]
Common stock, shares authorized					120,000,000
Common stock, shares authorized for issuance					121,000,000
Maximum [Member]
Shareholders' Equity [Line Items]
Common stock, shares authorized					240,000,000
Common stock, shares authorized for issuance					241,000,000
Common Stock [Member]
Shareholders' Equity [Line Items]
Dividend payable, date of record	Mar. 02, 2012
Dividend payable, date to be paid	Mar. 23, 2012