Share-based Compensation - Additional Information (Detail) (USD $)	3 Months Ended	6 Months Ended		6 Months Ended		3 Months Ended	6 Months Ended	3 Months Ended		6 Months Ended		3 Months Ended	6 Months Ended	3 Months Ended							6 Months Ended
	Jan. 31, 2014	Jan. 31, 2014	Nov. 04, 1985 Employee Stock Purchase Plan	Jan. 21, 2014 Employee Stock Purchase Plan Before Amendment	Jan. 21, 2014 Employee Stock Purchase Plan After Amendment	Jan. 31, 2014 Time Based Restricted Stock Awards	Jan. 31, 2014 Time Based Restricted Stock Awards	Jan. 31, 2014 Stock Options	Jan. 31, 2013 Stock Options	Jan. 31, 2014 Stock Options	Jan. 31, 2013 Stock Options	Jan. 31, 2014 Performance Based Restricted Stock Awards	Jan. 31, 2014 Performance Based Restricted Stock Awards	Jan. 31, 2014 TSR	Jan. 31, 2013 TSR	Jan. 31, 2014 Non-GAAP EPS Performance-Based Awards	Jan. 31, 2013 Non-GAAP EPS Performance-Based Awards	Jan. 21, 2014 2009 Stock Incentive Plan	Jan. 23, 2012 2009 Stock Incentive Plan	Jan. 29, 2010 2009 Stock Incentive Plan	Jan. 31, 2014 Stock Option and Restricted Stock Bonus Plans
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock shares authorized to be granted			700,000															4,453,518	2,200,000	1,600,000
Maximum value of stock per employees can purchase				$ 2,600	$ 12,500
Stock options granted								0
Weighted average grant date fair value of awards granted						$ 91.69	$ 79.69	$ 0.00	$ 26.54	$ 27.54	$ 24.80	$ 0.00	$ 93.76
Intrinsic value of options exercised	100,000	1,600,000
Stock options vested or expected to vest, shares								405,588		405,588
Stock options exercisable, shares								175,039		175,039
Stock options vested or expected to vest, weighted average exercise price								$ 63.21		$ 63.21
Stock options exercisable, weighted average exercise price								$ 54.88		$ 54.88
Stock options vested or expected to vest, aggregate intrinsic value								13,200,000		13,200,000
Stock options exercisable, aggregate intrinsic value								7,100,000		7,100,000
Stock options vested or expected to vest, weighted average remaining contractual term										5 years 4 months 6 days
Stock options exercisable, weighted average remaining contractual term										4 years 2 months 12 days
Options, grants in period														0	389	0	505
Total fair value of restricted stock grants vested in period	300,000	20,100,000
Unrecognized compensation cost related to non-vested share-based compensation arrangements																					$ 17,300,000
Unrecognized compensation cost related to non-vested share-based compensation arrangements, weighted average period																					1 year 7 months 6 days