Restructuring (Details Textual) (USD $)	3 Months Ended		9 Months Ended		12 Months Ended
	Jan. 31, 2012	Jan. 31, 2011	Jan. 31, 2012 Position Facility Y	Jan. 31, 2011	Apr. 30, 2011	Oct. 31, 2011
Restructuring (Textual) [Abstract]
Total expected restructuring charge	$ 245,000,000		$ 245,000,000			$ 235,000,000
Restructuring costs incurred announcement-to-date			175,000,000
Reduction in positions due to restructuring			850
Cost of products sold restructuring	12,022,000	16,851,000	33,492,000	38,376,000
Total restructuring charges	$ 25,571,000	$ 25,265,000	$ 67,294,000	$ 73,239,000	$ 101,957,000
Plants announced to be closed			6
Years over which balance of restructuring costs will be incurred			2