Stockholder's Investments - Summary of Stock Option Activity under Company's Share-Based Compensation Plans (Detail) (USD $)	12 Months Ended					12 Months Ended
	Jul. 31, 2013	Jul. 31, 2012	Jul. 31, 2011	Jul. 31, 2010	Dec. 31, 2012 Cliff-Vested Restricted Shares [Member]	Jul. 31, 2013 Service Based Option [Member]	Jul. 31, 2012 Service Based Option [Member]	Jul. 31, 2011 Service Based Option [Member]	Jul. 31, 2013 17.00 - 27.99 [Member]	Jul. 31, 2013 28.00 - 37.99 [Member]	Jul. 31, 2013 38.00 and Up [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedGranted					5,000
Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Price Lower Range	$ 17.23	$ 13.31	$ 13.31	$ 13.31
Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Price Upper Range	$ 40.37	$ 40.37	$ 40.37	$ 40.37
Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Price Lower Range	$ 30.21	$ 27.00	$ 28.35
Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Price Upper Range	$ 36.25	$ 33.54	$ 37.95
Share Based Compensation Arrangement By Share Based Payment Award Options Exercises In Period Price Lower Range	$ 13.31	$ 13.31	$ 14.16
Share Based Compensation Arrangement By Share Based Payment Award Options Exercises In Period Price Upper Range	$ 31.54	$ 29.78	$ 29.78
Share Based Compensation Arrangement By Share Based Payment Award Options Forfeitures In Period Price Lower Range	$ 16.39	$ 16.00	$ 16.39
Share Based Compensation Arrangement By Share Based Payment Award Options Forfeitures In Period Price Upper Range	$ 38.31	$ 38.31	$ 38.31
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Shares outstanding, beginning balance	6,253,751	5,726,017	5,108,736
Shares outstanding, new grants						828,450	1,212,450	1,365,500
Shares outstanding, exercised	(1,080,089)	(266,991)	(417,888)
Shares outstanding, forfeited or expired	(895,527)	(417,725)	(330,331)
Shares outstanding, ending balance	5,106,585	6,253,751	5,726,017						939,749	3,361,336	805,500
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Roll Forward]
Options outstanding, beginning balance, weighted average exercise price (USD per share)	$ 29.24	$ 29.24	$ 28.69
Options outstanding, new grants, weighted average exercise price (USD per share)						$ 30.58	$ 27.91	$ 28.86
Options outstanding, exercised, weighted average exercise price (USD per share)	$ 22.79	$ 20.21	$ 19.62
Options outstanding, forfeited or expired, weighted average exercise price (USD per share)	$ 30.02	$ 31.16	$ 31.37
Options outstanding, ending balance, weighted average exercise price (USD per share)	$ 30.68	$ 29.24	$ 29.24						$ 24.67	$ 30.54	$ 38.26
Options outstanding, ending balance, weighted average remaining contractual term	5 years 8 months 12 days								6 years 4 months 24 days	6 years	3 years 2 months 12 days
Options outstanding, exercisable	3,311,043	3,503,963	3,316,815						561,740	1,943,803	805,500
Weighted average exercise price of options exercisable	$ 31.46	$ 29.69	$ 29.83						$ 23.11	$ 31.05	$ 38.26