Restructuring (Details Textual) (USD $)	3 Months Ended		12 Months Ended
	Jul. 31, 2011	Jul. 31, 2010	Apr. 30, 2011
Restructuring (Textuals) [Abstract]
Total expected restructuring charge	$ 235,000,000
Restructuring costs incurred announcement-to-date	127,200,000
Total restructuring charges	19,563,000	27,557,000	101,957,000
Reduction in positions due to restructuring	850
Cost of products sold restructuring	$ 9,666,000	$ 9,453,000
Plants announced to be closed	6
Years over which balance of restructuring costs will be incurred	3