Share-Based Compensation - Stock Option Activity (Detail) (USD $)	12 Months Ended
	Jul. 31, 2012	Jul. 31, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options exercisable, weighted average contractual term	6 years 11 days	5 years 7 months 2 days
Options vested and expected to vest, weighted average contractual term.	5 years 11 months 19 days
Options exercisable at end of period, weighted average contractual term	5 years 22 days
Beginning balance, weighted average exercise price	$ 20.33
Options granted, weighted average exercise price	$ 18.37
Options exercised, weighted average exercise price	$ 17.40
Options cancelled, weighted average exercise price	$ 21.91
Ending balance, weighted average exercise price	$ 19.96	$ 20.33
Options vested and expected to vest, weighted average exercise price	$ 19.95
Options exercisable at end of period, weighted average exercise price	$ 19.80
Beginning balance, shares	2,993,840
Options granted, shares	17,875
Options exercised, shares	(140,485)
Options cancelled, shares	(729,940)
Ending balance, shares	2,141,290	2,993,840
Options vested and expected to vest , shares	2,098,875
Options exercisable at end of period, shares	1,524,776