Employee Benefit Plans (Details 4)	12 Months Ended
	Jul. 31, 2012	Jul. 31, 2011	Jul. 31, 2010
Assumptions Used In Accounting For Plan
Weighted average discount rate used in determining accumulated postretirement benefit obligation liability	3.25%	4.50%	4.50%
Weighted average discount rate used in determining net periodic benefit cost	4.50%	4.50%	5.50%
Assumed health care trend rate used to measure APBO at July 31	8.00%	8.00%	8.00%
Rate to which cost trend rate is assumed to decline (the ultimate trend rate)	5.50%	5.50%	5.50%
Fiscal year the ultimate trend rate is reached	2016	2017	2016