Share-Based Payments - Additional Information (Detail) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended						12 Months Ended												12 Months Ended
	Jul. 31, 2013	Jul. 31, 2012	Jul. 31, 2011	Jul. 31, 2013 2005 Plan	Jul. 31, 2013 2010 Plan	Dec. 08, 2010 2010 Plan	Jul. 31, 2013 ESPP	Jul. 31, 2012 ESPP	Jul. 31, 2011 ESPP	Jul. 31, 2013 Restricted Stock	Jul. 31, 2013 Stock Option	Jul. 31, 2013 Stock Option 2005 Plan	Jul. 31, 2013 Performance Options	Jul. 31, 2013 Performance Options First Anniversary TradingPrice	Jul. 31, 2013 Performance Options Second Anniversary TradingPrice	Jul. 31, 2013 Performance Options Third Anniversary TradingPrice	Jul. 31, 2013 Performance Options Fourth Anniversary TradingPrice	Jul. 31, 2013 Performance Options Fifth Anniversary TradingPrice	Jul. 31, 2013 Minimum	Jul. 31, 2012 Minimum	Jul. 31, 2013 Maximum	Jul. 31, 2012 Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercisable terms				3 years																1 year		3 years
Exercisable rate of options granted		25.00%											20.00%
Contractual terms, share options granted											7 years	10 years	7 years
Price performance threshold														1.5	2	2.5	3	3.5
2010 Plan number of shares pursuant to stock options granted	2,137,000				5,000,000
2010 Plan additional shares of Common Stock						2,922,258
Common Stock shares available for future issuance					3,354,365		210,000
Number of shares pursuant to stock options granted							600,000
Common stock purchase price as a percentage of market value							85.00%
Shares issued under plan							12,000	23,000	34,000
Weighted-average grant date fair value of employee stock options granted	$ 1.56	$ 1.98	$ 2.97
Unrecognized share-based compensation related to stock options	$ 3.0
Weighted average period of cost expected to be expensed										7 months 6 days	2 years 7 months 6 days
Stock options vested and expected to vest	2,400,000
Weighted-average remaining contractual term	4 years 11 months 27 days
Non vested stock compensation expense	1.1	1.6	1.6
Term of restriction period																			1 year		5 years
Grant date fair value of nonvested stock	2.2	2.1	1.5
Unrecognized compensation cost related to nonvested stock	$ 0.2