Property, Plant and Equipment - Additional Information (Detail) (USD $)	12 Months Ended
	Jul. 31, 2014	Jul. 31, 2013	Jul. 31, 2012
Property Plant And Equipment [Abstract]
Impairment charge for building and improvements		$ 4,359,000
Carrying value of the land, building and improvements	37,700,000	37,700,000
Depreciation and amortization expense	$ 15,700,000	$ 14,300,000	$ 15,900,000