Fire At Bus Production Facility (Narrative) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended		24 Months Ended
	Jul. 31, 2011	Jul. 31, 2010	Jul. 31, 2011
Fire At Bus Production Facility
Amount deductible per the policy	5,000
Insurance proceeds received	$ 10,203
Insurance recoveries recognized	10,437	18,079	28,516
Insurance proceeds which included for business interruption	6,315
Insurance proceeds received		13,313
Insurance recoveries, net of deductibles		13,079
Advances recorded as deferred revenue		234
Insurance proceeds recognized in current year, previously deferred	234
Gain on involuntary conversion	9,417	7,593	17,010
Cost incurred to reconstruct the Facility	$ 5,460		$ 6,943