Inventories (Details) (USD $)	Apr. 30, 2012	Jul. 31, 2011
Inventories [Abstract]
Materials	$ 112,706,000	$ 110,466,000
Work in process	32,659,000	33,917,000
Finished products	120,096,000	127,093,000
Total inventories	265,461,000	271,476,000
Obsolete inventory reserves	$ 13,400,000	$ 14,500,000