Stock-Based Compensation - Summary of Stock Option Activity under Company's Share-Based Compensation Plans (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended					3 Months Ended
	Oct. 31, 2013	Oct. 31, 2012	Oct. 31, 2013 Service Based Option [Member]	Oct. 31, 2013 Restricted Stock [Member]	Jul. 31, 2013 Restricted Stock [Member]	Oct. 31, 2013 Restricted Stock Units (RSUs) [Member]	Jul. 31, 2013 Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value				$ 31.48	$ 31.52	$ 30.99	$ 30.21
Share-based Compensation	$ 2,600	$ 4,399
Total stock compensation expense, net of tax	1,586	2,683
Shares outstanding, beginning balance	5,106,585			226,667		10,000
Shares outstanding, new grants			347,145	5,000		95,765
Shares outstanding, exercised	(213,548)
Shares outstanding, forfeited or expired	(434,848)
Shares outstanding, ending balance	4,805,334			231,667		105,358
Options outstanding, exercisable	3,466,777	4,231,429
Options outstanding, beginning balance, weighted average exercise price (USD per share)	$ 30.68
Options outstanding, new grants, weighted average exercise price (USD per share)			$ 31.07
Options outstanding, exercised, weighted average exercise price (USD per share)	$ 27.06
Options outstanding, forfeited or expired, weighted average exercise price (USD per share)				$ 0		$ 31.07
Options outstanding, ending balance, weighted average exercise price (USD per share)	$ 30.68
Weighted average exercise price of options exercisable	$ 30.93	$ 29.78
Options outstanding, ending balance, weighted average remaining contractual term	6 years 1 month 6 days
Options outstanding, exercisable, weighted average remaining contractual term	5 years 1 month 6 days
Options outstanding, ending balance, aggregate intrinsic value	4,518
Options outstanding, exercisable, aggregate intrinsic value	4,079
Fair Value Options Vested During Period	8,383	6,330
Proceeds from Stock Options Exercised	$ 5,209	$ 1,684
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value				$ 29.70		$ 31.07
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period				0		(407)
Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures and Expirations in Period, Weighted Average Exercise Price	$ 32.79