Shareholders' Equity (Narrative) (Details) (USD $) In Millions, except Share data, unless otherwise specified	0 Months Ended		3 Months Ended	9 Months Ended
	May 23, 2012	Mar. 23, 2012	Apr. 30, 2012	Apr. 30, 2012	Jan. 27, 2012	Nov. 18, 2011	Jul. 31, 2011	Mar. 26, 2010
Common stock authorized for repurchase								16,000,000
Stock repurchased during the period, shares			261,213	3,012,239
Stock repurchased during the period, value			$ 9.0	$ 82.6
Average price per share			$ 34.51	$ 27.41
Shares with remaining authorization for repurchase under stock repurchase plan			7,000,000	7,000,000
Cash dividend declared per common share	$ 0.09
Common stock, share par value			$ 5	$ 5		$ 5.00	$ 5
Common stock, shares authorized			240,000,000	240,000,000		120,000,000	240,000,000
Percentage of stock dividend effected due to stock split					100.00%
Dividend payable, date of record				Jun. 08, 2012
Dividend payable, date to be paid				Jun. 29, 2012
Stock split		2
Minimum [Member]
Number of shares of stock the Company has the authority to issue						121,000,000
Maximum [Member]
Number of shares of stock the Company has the authority to issue						241,000,000
Newly Approved Number Of Authorized Shares [Member]
Common stock, shares authorized						240,000,000