Employee Benefit Plans (Details 3) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Jul. 31, 2012	Jul. 31, 2011	Jul. 31, 2010
Net periodic benefit costs table
Service cost - benefits attributed to service during the period	$ 644	$ 666	$ 662
Prior service credit	(203)	(82)	(64)
Interest cost on accumulated postretirement benefit obligation	633	694	795
Amortization of unrecognized gain	(189)	(76)	(206)
Periodic postretirement benefit cost	$ 885	$ 1,202	$ 1,187