Shareholders' Equity (Narrative) (Details) (USD $) In Millions, except Share data, unless otherwise specified	0 Months Ended		3 Months Ended		6 Months Ended
	Jan. 25, 2013	Jan. 27, 2012	Jan. 31, 2013	Apr. 30, 2012	Jan. 31, 2013
Shareholders' Equity [Abstract]
Common stock authorized for repurchase			16,000,000		16,000,000
Stock repurchased during the period, shares			320,442		1,820,442
Stock repurchases during the period, value			$ 10.2		$ 61.0
Average price per share			$ 31.97		$ 33.49
Shares with remaining authorization for repurchase under stock repurchase plan			3,700,000		3,700,000
Percentage of stock dividend effected due to stock split		100.00%
Stock split ratio		2		2
Cash dividend declared per common share	$ 0.10