Employees' Stock Incentive Plans and Management Incentive Plans (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Jul. 29, 2012	Jul. 27, 2011
Employees Stock Incentive Plans And Management Incentive Plans (Textuals) [Abstract]
Performance Period In Years For Dividends Paid	2 years
Number Of Trading Days For L T T P Peer Group Company Stock Price	60 days
Selling, General and Administrative Expenses [Member] | Stock Option and Restricted Stock Plans [Member]
Employees Stock Incentive Plans And Management Incentive Plans (Textuals) [Abstract]
Pre-tax compensation cost	$ 6.9	$ 6.0
Tax benefit	2.1	1.7
After-tax compensation cost	4.8	4.3
Selling, General and Administrative Expenses [Member] | LTPP [Member]
Employees Stock Incentive Plans And Management Incentive Plans (Textuals) [Abstract]
Pre-tax compensation cost	8.7	5.6
Tax benefit	3.0	1.9
After-tax compensation cost	$ 5.7	$ 3.7