Significant Accounting Policies (Schedule Of Depreciation Of Property, Plant And Equipment) (Details)	12 Months Ended
	Apr. 30, 2012
Buildings [Member] | Minimum [Member]
Significant Accounting Policies [Line Items]
Useful life	25 years
Buildings [Member] | Maximum [Member]
Significant Accounting Policies [Line Items]
Useful life	40 years
Machinery and Equipment [Member] | Minimum [Member]
Significant Accounting Policies [Line Items]
Useful life	5 years
Machinery and Equipment [Member] | Maximum [Member]
Significant Accounting Policies [Line Items]
Useful life	30 years
Leasehold Interest In Property And Equipment [Member]
Significant Accounting Policies [Line Items]
Useful Life	Lesser of term of lease or life of asset
Leasehold Improvements [Member]
Significant Accounting Policies [Line Items]
Useful Life	Lesser of term of lease or life of asset