Fair Value Measurements (Details) (USD $) In Millions	Jul. 30, 2011	Apr. 30, 2011
Cash equivalents	$ 170.9	$ 188.2
Derivative instruments, assets	3.1	5.5
Total assets	174.0	193.7
Derivative instruments, liabilities	3.1	5.6
Quoted Prices in Active Markets (Level 1) [Member]
Cash equivalents	170.9	188.2
Derivative instruments, assets	0	0
Total assets	170.9	188.2
Derivative instruments, liabilities	0	0
Significant Other Observable Inputs (Level 2) [Member]
Cash equivalents	0	0
Derivative instruments, assets	3.1	5.5
Total assets	3.1	5.5
Derivative instruments, liabilities	3.1	5.6
Significant Unobservable Inputs (Level 3) [Member]
Cash equivalents	0	0
Derivative instruments, assets	0	0
Total assets	0	0
Derivative instruments, liabilities	$ 0	$ 0