Stockholders' Equity - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands		12 Months Ended
	May. 15, 2015	Jul. 31, 2015	Jul. 31, 2014	Jul. 31, 2013
Stock Based Compensation And Stockholders Equity [Line Items]
Common stock purchased, shares	1,000,000
Common stock price per share	$ 60.00
Aggregate purchase price of common stock	$ 60,000	$ 60,000
Closing price of common stock	$ 61.29
Percentage of issued and outstanding common stock prior to repurchase	1.90%
Option expiration from the date of grant, in years		10 years
Options granted during the period		0	0	0
Cash received from stock option exercises		$ 141	$ 3,206	$ 5,845
Total intrinsic value of stock options exercised		$ 168	$ 2,597	$ 7,502
Stock option exercised		5,000	101,313	498,412
Stock option value exercised		$ 141	$ 3,206	$ 14,267
Cashless exercises of stock options (in shares)				63,464
Shares repurchased related to cashless exercise of stock options				$ 2,009
Total unrecognized compensation costs		$ 9,375
Period for recognition of compensation cost not yet recognized		2 years 1 month 24 days
Stock-based compensation		$ 6,776	5,231	2,816
Tax benefits from stock compensation expense		2,507	1,925	1,032
Discontinued Operations
Stock Based Compensation And Stockholders Equity [Line Items]
Total compensation expenses		$ 0	480	$ 207
Minimum
Stock Based Compensation And Stockholders Equity [Line Items]
Option vesting period		3 years
Maximum
Stock Based Compensation And Stockholders Equity [Line Items]
Option vesting period		5 years
Cashless Exercise
Stock Based Compensation And Stockholders Equity [Line Items]
Stock option exercised				314,000
Stock Option Awards
Stock Based Compensation And Stockholders Equity [Line Items]
Total compensation expenses		$ 0	0	$ 393
Restricted Stock Awards
Stock Based Compensation And Stockholders Equity [Line Items]
Option vesting period		5 years
Total compensation expenses		$ 115	91	133
Total unrecognized compensation costs		$ 216
Period for recognition of compensation cost not yet recognized		1 year 11 months 19 days
2010 Equity Incentive Plan
Stock Based Compensation And Stockholders Equity [Line Items]
Number of shares authorized under stock option plan		2,000,000
Number of shares available to be granted		1,393,257
2006 Equity Incentive Plan
Stock Based Compensation And Stockholders Equity [Line Items]
Number of shares authorized under stock option plan		1,100,000
Number of shares available to be granted		30,000
Restricted Stock Units (RSUs)
Stock Based Compensation And Stockholders Equity [Line Items]
Total compensation expenses		$ 6,661	$ 5,140	$ 2,290