Stock Based Compensation - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Oct. 31, 2015	Oct. 31, 2014
Incentive Stock Plan
Shares authorized	4,968,479
Shares reserved for future issuance	2,238,223
Stock-Based Compensation Expense
Share-based compensation expense	$ 2,596	$ 1,319
Share-based compensation expense, net of tax	1,609	818
Unrealized compensation cost related to share-based compensation, pre tax	$ 21,053
Weighted average period remaining	3 years
Stock Options, Additional Disclosures
Proceeds from stock options exercised		91
Tax benefit on options exercised		3
Fair value of options vested	$ 2,964	$ 3,684
Service-Based RSUs, Additional Disclosures
Service-Based RSUs, Grants in Period, Weighted Average Grant Date Fair Value	$ 19.98	$ 23.45
Service-Based RSUs, Nonvested, Aggregate Intrinsic Value,	$ 17,017
Service-Based RSUs, Vested in Period, Fair Value	$ 1,419	$ 762