Retirement and Profit Sharing Plans (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Jul. 31, 2013 hour	Jul. 31, 2012	Jul. 31, 2011
Compensation and Retirement Disclosure [Abstract]
Employee contribution percentage	100.00%
Company match amount equal to participant's contribution	50.00%
Employer contribution matching equal to 50%	6.00%
Employment period (in months)	12 months
Service period (in hours)	1,000
Total service period (in hours)	1,500
Retirement plan expense	$ 3.7	$ 2.4	$ 1.5